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Sample records for antilles assemblage structure

  1. Reef fishes of Saba Bank, Netherlands Antilles: assemblage structure across a gradient of habitat types

    OpenAIRE

    Toller, W; Debrot, A.O.; Vermeij, M.J.A.; Hoetjes, P.C.

    2010-01-01

    Saba Bank is a 2,200 km2 submerged carbonate platform in the northeastern Caribbean Sea off Saba Island, Netherlands Antilles. The presence of reef-like geomorphic features and significant shelf edge coral development on Saba Bank have led to the conclusion that it is an actively growing, though wholly submerged, coral reef atoll. However, little information exists on the composition of benthic communities or associated reef fish assemblages of Saba Bank. We selected a 40 km2 area of the bank...

  2. Seismological Insights into the Structure of the Lesser Antilles

    Science.gov (United States)

    Schlaphorst, D.; Kendall, J.; Bastow, I. D.; Baptie, B.

    2012-12-01

    Due to an overall eastwards drift of the Caribbean plate of around 2cm/year relative to the Atlantic plate, the type of the subduction along the eastern part of the Caribbean changes. Compared to the simple subduction of the Atlantic plate in the east, the northern plate boundary zone is far more complex, predominantly characterised by a left-lateral east-west strike-slip motion that includes an oblique convergence of the Bahamas carbonate banks and a pull apart basin in the Mona Passage, the sea gate between Hispaniola and Puerto Rico. The island of Hispaniola is decoupled from the Caribbean plate, which leads to a second subduction zone south of Hispaniola where the Caribbean plate subducts beneath the Hispaniola micro plate. Strictly speaking, the arc only extends to the east of the island of Puerto Rico but since most of the northern Caribbean plate boundary zone is directly linked to it the results become more directly comparable. Fed by the Orinoco River the southern part of the Lesser Antilles is a sediment-rich subduction zone, which becomes sediment-poor towards the north as the sediments get blocked by several banks, including the accretionary prism containing the island of Barbados. Here we investigate the crustal and mantle structure variation along the Antilles Arc using measurements of seismic anisotropy and receiver functions. We use data from three component broadband stations that are located from the southern end of the arc to Hispaniola in the north. Seismic anisotropy refers to directional variations in wave speeds and their polarisations. The observation of two independently propagating shear waves (splitting) is the least ambiguous indication of anisotropy. Such observations can be used to constrain mantle flow beneath subduction regions, offering insights into slab dynamics. We generally observed trench parallel orientations around the plate boundary. However, we see significant local deviations in the inferred flow pattern, for example, in

  3. Climate mediates the effects of disturbance on ant assemblage structure

    Czech Academy of Sciences Publication Activity Database

    Gibb, H.; Sanders, N. J.; Dunn, R. R.; Watson, S.; Photakis, M.; Abril, S.; Andersen, A. N.; Angulo, E.; Armbrecht, I.; Arnan, X.; Baccaro, F. B.; Bishop, T. R.; Boulay, R.; Castracani, C.; Del Toro, I.; Delsinne, T.; Diaz, M.; Donoso, D. A.; Enríquez, M. L.; Fayle, Tom; Feener Jr., D. H.; Fitzpatrik, M. C.; Gómez, C.; Grasso, D. A.; Groc, S.; Heterick, B.; Hoffmann, B. D.; Lach, L.; Lattke, J.; Leponce, M.; Lessard, J.-P.; Longino, J.; Lucky, A.; Majer, J.; Menke, S. B.; Mezger, D.; Mori, A.; Munyai, T. C.; Paknia, O.; Pearce-Duvet, J.; Pfeiffer, M.; Philpott, S. M.; de Souza, J. L. P.; Tista, M.; Vasconcelos, H. L.; Vonshak, M.; Parr, C. L.

    2015-01-01

    Roč. 282, č. 1808 (2015), article number 20150418. ISSN 0962-8452 Institutional support: RVO:60077344 Keywords : assemblage structure * dominance * global warming Subject RIV: EH - Ecology, Behaviour Impact factor: 5.051, year: 2014

  4. Remote sensing observations of the coherent and non-coherent ring structures in the vicinity of Lesser Antilles

    Directory of Open Access Journals (Sweden)

    R. C. Cruz Gómez

    2007-03-01

    Full Text Available The North Brazil Current Rings (NBCR penetration into the Caribbean Sea is being investigated by employing a merged altimeter-derived sea height anomaly (TOPEX/Poseidon, Jason-1 and ERS-1, 2, the ocean surface color data (SeaWiFS and Global Drifter Program information. Four strategies are being applied to process the data: (1 calculations of the Okubo-Weiss parameter for NBCR identification, (2 longitude-time plots (also known as Hovmöller diagrams, (3 two-dimensional Radon transforms and (4 two-dimensional Fourier transforms.

    A twofold NBCR structure has been detected in the region under investigation. The results have shown that NBC rings mainly propagate into the Caribbean Sea along two principal pathways (near 12° N and 17° N in the ring translation corridor. Thus, rings following the southern pathway in the fall-winter period can enter through very shallow southern straits as non-coherent structures. A different behavior is observed near the northern pathway (~17° N, where NBC rings are thought to have a coherent structure during their squeezing into the eastern Caribbean, i.e. conserving the principal characteristics of the incident rings. We attribute this difference in the rings' behavior to the vertical scales of the rings and to the bottom topography features in the vicinity of the Lesser Antilles.

  5. Climate mediates the effects of disturbance on ant assemblage structure

    Science.gov (United States)

    Gibb, Heloise; Sanders, Nathan J.; Dunn, Robert R.; Watson, Simon; Photakis, Manoli; Abril, Silvia; Andersen, Alan N.; Angulo, Elena; Armbrecht, Inge; Arnan, Xavier; Baccaro, Fabricio B.; Bishop, Tom R.; Boulay, Raphael; Castracani, Cristina; Del Toro, Israel; Delsinne, Thibaut; Diaz, Mireia; Donoso, David A.; Enríquez, Martha L.; Fayle, Tom M.; Feener, Donald H.; Fitzpatrick, Matthew C.; Gómez, Crisanto; Grasso, Donato A.; Groc, Sarah; Heterick, Brian; Hoffmann, Benjamin D.; Lach, Lori; Lattke, John; Leponce, Maurice; Lessard, Jean-Philippe; Longino, John; Lucky, Andrea; Majer, Jonathan; Menke, Sean B.; Mezger, Dirk; Mori, Alessandra; Munyai, Thinandavha C.; Paknia, Omid; Pearce-Duvet, Jessica; Pfeiffer, Martin; Philpott, Stacy M.; de Souza, Jorge L. P.; Tista, Melanie; Vasconcelos, Heraldo L.; Vonshak, Merav; Parr, Catherine L.

    2015-01-01

    Many studies have focused on the impacts of climate change on biological assemblages, yet little is known about how climate interacts with other major anthropogenic influences on biodiversity, such as habitat disturbance. Using a unique global database of 1128 local ant assemblages, we examined whether climate mediates the effects of habitat disturbance on assemblage structure at a global scale. Species richness and evenness were associated positively with temperature, and negatively with disturbance. However, the interaction among temperature, precipitation and disturbance shaped species richness and evenness. The effect was manifested through a failure of species richness to increase substantially with temperature in transformed habitats at low precipitation. At low precipitation levels, evenness increased with temperature in undisturbed sites, peaked at medium temperatures in disturbed sites and remained low in transformed sites. In warmer climates with lower rainfall, the effects of increasing disturbance on species richness and evenness were akin to decreases in temperature of up to 9°C. Anthropogenic disturbance and ongoing climate change may interact in complicated ways to shape the structure of assemblages, with hot, arid environments likely to be at greatest risk. PMID:25994675

  6. Crustal structure of Guadeloupe Islands and the Lesser Antilles Arc from a new gravity and magnetic synthesis

    OpenAIRE

    Gailler, Lydie; Bouchot, Vincent; Martelet, Guillaume; Thinon, Isabelle; Lebrun, Jean-Frédéric; Münch, Philippe

    2012-01-01

    Guadeloupe Island (West French Indies) is one of the twenty islands that compose the Lesser Antilles Arc, which results from the subduction of the Atlantic Ocean plate beneath the Caribbean one. The island lies in a complex volcano-tectonic system and the need to understand its geological context has led to numerous on- and offshore geophysical investigations. This work presents the compilation and processing of available, on-land, airborne and marine, gravity and magnetic data acquired durin...

  7. Oblique collision and accretion of the Netherlands Leeward Antilles island arc: A structural analysis of the Caribbean-South American plate boundary zone

    Science.gov (United States)

    Beardsley, Amanda Gail

    2007-12-01

    The Netherlands Leeward Antilles volcanic island arc is an ideal natural laboratory to study the evolution of the Caribbean-South American plate boundary. The Leeward Antilles islands (Aruba, Curacao, and Bonaire) are located offshore western Venezuela, within the obliquely convergent diffuse plate boundary zone. Outcrop analysis, microthermometry, and 2D marine seismic reflection data provide evidence of three generations of regional deformation since the Late Cretaceous. Outcrop analysis of structural features, including faults, joints, and veins, characterizes the kinematic history of the islands. Fluid inclusion analysis of quartz and calcite veins coupled with apatite fission-track dating provides the island exhumation history. Finally, marine reflection seismic data processing and interpretation of newly acquired data elucidates offshore structures to integrate with our onshore results. The oldest regional deformation, resulting in both ductile (D1) and brittle (F 1) structures, is attributed to displacement partitioning along the arcuate Caribbean plate boundary. Associated crustal thinning initiated island exhumation, at a rate of 0.18 km/my, from a maximum burial depth of 6 km in the Late Cretaceous (˜89 Ma). Coeval with D1/F1 deformation and exhumation, stretching of the island arc resulted in extensive basin rifting that separated the island blocks. At ˜55 Ma, a change in the relative motion of the Caribbean plate altered plate boundary dynamics. Displacement along the right-lateral Caribbean transform fault and Oca - San Sebastian - El Pilar strike-slip fault system created a wrench tectonic regime within the diffuse plate boundary zone. A second generation of brittle structures (F2) developed while the islands were at a maximum burial depth of 2 km during the Paleocene/Eocene. Since ˜45 Ma, continued motion along the strike-slip fault systems and oblique plate convergence resulted in the youngest generation of structural features (F3). Regional

  8. Structure of molluscan assemblages in sheltered intertidal unconsolidated environments

    Directory of Open Access Journals (Sweden)

    Márcia Regina Denadai

    2005-09-01

    Full Text Available The molluscan macrofauna from 13 oceanic sheltered intertidal unconsolidated environments and its relationship with abiotic factors were studied in order to establish the degree of species richness and to understand the role environment plays in structuring such assemblages. Four distinct intertidal habitat types were recognized based on molluscan assemblage descriptors (diversity, richness and density and abiotic characteristics. The mean grain size (in phy units and the beach slope showed a negative relationship with the diversity, richness and density. Coarser sediments were favorable to molluscan fauna in the study areas, contrasting the well-known negative effect of this type of sand on fauna in typical oceanic beaches. The low-tide terraces, typical from tide-dominated areas, and the presence of physical (rocky fragments and biogenic (gravel structures, were also associated to the higher values of richness. The high richness in the study area as a whole seemed to be a direct consequence of its environmental heterogeneity, once it was composed by quite distinct habitat types.A malacofauna de 13 ambientes oceânicos, protegidos, entremarés e não-consolidados e sua relação com os fatores abióticos foram estudados com o intuito de conhecer a riqueza de espécies e compreender o papel dos fatores abióticos na estruturação das associações. Quatro tipos distintos de ambiente entremarés foram reconhecidos com base nos descritores da comunidade (diversidade, riqueza e densidade e nas características abióticas. O tamanho médio do grão de areia (em phy e a inclinação da praia mostraram uma relação negativa com a diversidade, riqueza e densidade. Sedimentos grossos foram favoráveis à fauna de moluscos nas áreas estudadas, contrastando o bem conhecido efeito negativo deste tipo de areia sobre a fauna em praias oceânicas típicas. Os terraços de maré baixa, típicos de áreas dominadas pela maré, e a presença de estruturas

  9. Tipification of oligotrophic lakes using the ciliate assemblage structure

    Czech Academy of Sciences Publication Activity Database

    Macek, Miroslav; Lugo-Vázquez, A.; Šimek, Karel

    Messina: Istituto per l Ambiente Marino Costiero, 2002 - (Giuliano, L.; Yakimov, M.). s. L112 [Symposium on Aquatic Microbial Ecology SAME-8 /8./. 25.10.2002-30.10.2002, Taormina] Institutional research plan: CEZ:AV0Z6017912 Keywords : tipification * oligotrophic lakes * ciliate assemblage Subject RIV: DA - Hydrology ; Limnology

  10. Structure of Mesophotic Reef Fish Assemblages in the Northwestern Hawaiian Islands

    Science.gov (United States)

    Kosaki, Randall K.; Wagner, Daniel; Kane, Corinne

    2016-01-01

    Mesophotic coral ecosystems (MCEs) support diverse communities of marine organisms with changes in community structure occurring along a depth gradient. In recent years, MCEs have gained attention due to their depths that provide protection from natural and anthropogenic stressors and their relative stability over evolutionary time periods, yet ecological structures of fish assemblages in MCEs remain largely un-documented. Here, we investigated composition and trophic structure of reef fish assemblages in the Northwestern Hawaiian Islands (NWHI) along a depth gradient from 1 to 67 m. The structure of reef fish assemblages as a whole showed a clear gradient from shallow to mesophotic depths. Fish assemblages at mesophotic depths had higher total densities than those in shallower waters, and were characterized by relatively high densities of planktivores and invertivores and relatively low densities of herbivores. Fishes that typified assemblages at mesophotic depths included six species that are endemic to the Hawaiian Islands. The present study showed that mesophotic reefs in the NWHI support unique assemblages of fish that are characterized by high endemism and relatively high densities of planktivores. Our findings underscore the ecological importance of these undersurveyed ecosystems and warrant further studies of MCEs. PMID:27383614

  11. Ophiuroidea of the Lesser Antilles

    NARCIS (Netherlands)

    Parslow, Rosemary E.; Clark, Ailsa M.

    1963-01-01

    This paper deals mainly with a collection of ophiuroids from the Lesser Antilles sent to the British Museum (Natural History) by Dr. P. WAGENAAR HUMMELINCK in 1959. The identifications were made by ROSEMARY PARSLOW, but the discussion and figures of Amphiodia and Ophiocomella are by AILSA CLARK. The

  12. Scaling the relative dominance of exogenous drivers in structuring desert small mammal assemblages

    Science.gov (United States)

    Rodríguez, Daniela; Ojeda, Ricardo A.

    2015-11-01

    Assemblage patterns could be primarily generated by two types of drivers: exogenous (such as environmental and climatic factors) and endogenous (interactions such as competition, predation, mutualism or herbivory). The most widely accepted hypothesis states that at smaller scales (such as patch scale), interspecific interactions are the major drivers structuring communities, whereas at larger regional scales, factors such as climate, topography and soil act as ecological filters that determine assemblage composition. The general aim of this paper is to compare different exogenous drivers in terms of their relative dominance in structuring desert small mammal communities across a range of spatial scales, from patch to regional, and compare them with previous results on endogenous drivers. Our results show that as spatial scale increases, the explanatory power of exogenous factors also increases, e.g. from 17% at the patch scale (i.e. abundance) to 99% at the regional scale (i.e. diversity). Moreover, environmental drivers vary in type and strength depending on the community estimator across several spatial scales. On the other hand, endogenous drivers such as interspecific interactions are more important at the patch scale, diminishing in importance towards the regional scale. Therefore, the relative importance of exogenous versus endogenous drivers affects small mammal assemblage structure at different spatial scales. Our results fill up a knowledge gap concerning ecological drivers of assemblage structure at intermediate spatial scales for Monte desert small mammals, and highlight the importance of dealing with multi-causal factors in explaining ecological patterns of assemblages.

  13. Structure and composition of the liana assemblage of a mixed rainforest in the Congo Basin

    NARCIS (Netherlands)

    Ewango, C.E.N.; Bongers, F.; Makana, J.R.; Poorter, L.; Sosef, M.S.M.

    2015-01-01

    Background and aims – The Congo Basin lowland forest represents one of the largest tropical forest blocks in the world, but its liana assemblage has never been characterized. We evaluate liana floristics, diversity, and structure in the Ituri Forest, and determine the effects of forest structure and

  14. Rare species contribute disproportionately to the functional structure of species assemblages.

    Science.gov (United States)

    Leitão, Rafael P; Zuanon, Jansen; Villéger, Sébastien; Williams, Stephen E; Baraloto, Christopher; Fortunel, Claire; Mendonça, Fernando P; Mouillot, David

    2016-04-13

    There is broad consensus that the diversity of functional traits within species assemblages drives several ecological processes. It is also widely recognized that rare species are the first to become extinct following human-induced disturbances. Surprisingly, however, the functional importance of rare species is still poorly understood, particularly in tropical species-rich assemblages where the majority of species are rare, and the rate of species extinction can be high. Here, we investigated the consequences of local and regional extinctions on the functional structure of species assemblages. We used three extensive datasets (stream fish from the Brazilian Amazon, rainforest trees from French Guiana, and birds from the Australian Wet Tropics) and built an integrative measure of species rarity versus commonness, combining local abundance, geographical range, and habitat breadth. Using different scenarios of species loss, we found a disproportionate impact of rare species extinction for the three groups, with significant reductions in levels of functional richness, specialization, and originality of assemblages, which may severely undermine the integrity of ecological processes. The whole breadth of functional abilities within species assemblages, which is disproportionately supported by rare species, is certainly critical in maintaining ecosystems particularly under the ongoing rapid environmental transitions. PMID:27053754

  15. Tropical rain-forest matrix quality affects bat assemblage structure in secondary forest patches

    NARCIS (Netherlands)

    Vleut, I.; Levy-Tacher, I.; Galindo-Gonzalez, J.; Boer, de W.F.; Ramirez-Marcial, N.

    2012-01-01

    We studied Phyllostomidae bat assemblage structure in patches of secondary forest dominated by the pioneer tree Ochroma pyramidale, largely (.85%) or partially (,35%) surrounded by a matrix of tropical rain forest, to test 3 hypotheses: the highest bat diversity and richness is observed in the matri

  16. A multi-scaled approach to evaluating the fish assemblage structure within southern Appalachian streams USA.

    Science.gov (United States)

    Kirsch, Joseph; Peterson, James T.

    2014-01-01

    There is considerable uncertainty about the relative roles of stream habitat and landscape characteristics in structuring stream-fish assemblages. We evaluated the relative importance of environmental characteristics on fish occupancy at the local and landscape scales within the upper Little Tennessee River basin of Georgia and North Carolina. Fishes were sampled using a quadrat sample design at 525 channel units within 48 study reaches during two consecutive years. We evaluated species–habitat relationships (local and landscape factors) by developing hierarchical, multispecies occupancy models. Modeling results suggested that fish occupancy within the Little Tennessee River basin was primarily influenced by stream topology and topography, urban land coverage, and channel unit types. Landscape scale factors (e.g., urban land coverage and elevation) largely controlled the fish assemblage structure at a stream-reach level, and local-scale factors (i.e., channel unit types) influenced fish distribution within stream reaches. Our study demonstrates the utility of a multi-scaled approach and the need to account for hierarchy and the interscale interactions of factors influencing assemblage structure prior to monitoring fish assemblages, developing biological management plans, or allocating management resources throughout a stream system.

  17. Despotic, high-impact species and the subcontinental scale control of avian assemblage structure.

    Science.gov (United States)

    MacNally, Ralph; Bowen, Michiala; Howes, Alison; McAlpine, Clive A; Maron, Martine

    2012-03-01

    Some species have disproportionate influence on assemblage structure, given their numbers or biomass. Most examples of such "strong interactors" come from small-scale experiments or from observations of the effects of invasive species. There is evidence that entire avian assemblages in open woodlands can be influenced strongly by individual species over very large areas in eastern Australia, with small-bodied species ( 2000 km). A series of linked Bayesian models was used to identify large-bodied (> or = 50 g) bird species that were associated with changes in occurrence and abundance of small-bodied species. One native species, the Noisy Miner (Manorina melanocephala; family Meliphagidae), was objectively identified as the sole large-bodied species having similar detrimental effects in all districts, depressing occurrence of 57 of 71 small-bodied species. Adverse effects on abundances of small-bodied species were profound when the Noisy Miner occurred with mean site abundances > or = 1.6 birds/2 ha. The Noisy Miner may be the first species to have been shown to influence whole-of-avifauna assemblage structure through despotic aggressiveness over subcontinental scales. These substantial shifts in occurrence rates and abundances of small-bodied species flow on to alter species abundance distributions of entire assemblages over much of eastern Australia. PMID:22624220

  18. Sensitivity of metrics of phylogenetic structure to scale, source of data and species pool of hummingbird assemblages along elevational gradients.

    Directory of Open Access Journals (Sweden)

    Sebastián González-Caro

    Full Text Available Patterns of phylogenetic structure of assemblages are increasingly used to gain insight into the ecological and evolutionary processes involved in the assembly of co-occurring species. Metrics of phylogenetic structure can be sensitive to scaling issues and data availability. Here we empirically assess the sensitivity of four metrics of phylogenetic structure of assemblages to changes in (i the source of data, (ii the spatial grain at which assemblages are defined, and (iii the definition of species pools using hummingbird (Trochilidae assemblages along an elevational gradient in Colombia. We also discuss some of the implications in terms of the potential mechanisms driving these patterns. To explore how source of data influence phylogenetic structure we defined assemblages using three sources of data: field inventories, museum specimens, and range maps. Assemblages were defined at two spatial grains: coarse-grained (elevational bands of 800-m width and fine-grained (1-km(2 plots. We used three different species pools: all species contained in assemblages, all species within half-degree quadrats, and all species either above or below 2000 m elevation. Metrics considering phylogenetic relationships among all species within assemblages showed phylogenetic clustering at high elevations and phylogenetic evenness in the lowlands, whereas those metrics considering only the closest co-occurring relatives showed the opposite trend. This result suggests that using multiple metrics of phylogenetic structure should provide greater insight into the mechanisms shaping assemblage structure. The source and spatial grain of data had important influences on estimates of both richness and phylogenetic structure. Metrics considering the co-occurrence of close relatives were particularly sensitive to changes in the spatial grain. Assemblages based on range maps included more species and showed less phylogenetic structure than assemblages based on museum or field

  19. Imaging the structure of the Northern Lesser Antilles (Guadeloupe - Virgin Island) to assess the tectonic and thermo-mechanical behavior of an arcuate subduction zone that undergoes increasing convergence obliquity

    Science.gov (United States)

    Laurencin, M.; Marcaillou, B.; Klingelhoefer, F.; Jean-Frederic, L.; Graindorge, D.; Bouquerel, H.; Conin, M.; Crozon, J.; De Min, L.; De Voogd, B.; Evain, M.; Heuret, A.; Laigle, M.; Lallemand, S.; Lucazeau, F.; Pichot, T.; Prunier, C.; Rolandone, F.; Rousset, D.; Vitard, C.

    2015-12-01

    Paradoxically, the Northern Lesser Antilles is the less-investigated and the most tectonically and seismically complex segment of the Lesser Antilles subduction zone: - The convergence obliquity between the North American and Caribbean plates increases northward from Guadeloupe to Virgin Islands raising questions about the fore-arc tectonic partitioning. - The margin has undergone the subduction of the rough sediment-starved Atlantic Ocean floor spiked with ridges as well as banks docking, but the resulting tectonic deformation remains hypothetical in the absence of a complete bathymetry and of any seismic line. - Recent geodetic data and low historical seismic activity suggest a low interplate coupling between Saint-Martin and Anegada, but the sparse onshore seismometers located far from source zone cast doubt on this seismic gap. To shed new light on these questions, the ANTITHESIS project, 5 Marine Geophysical legs totaling 72 days, aims at recording a complete bathymetric map, deep and shallow seismic reflexion lines, wide-angle seismic data, heat-flow measurements and the seismic activity with a web of sea-bottom seismometers. Our preliminary results suggest that: - A frontal sliver of accretionary prism is stretched and expulsed northward by 50km along the left-lateral Bunce fault that limits the prism from the margin basement as far southward as 18.5°N. So far, this structure is the only interpreted sign of tectonic partitioning in the fore-arc. - The Anegada Passage extends eastward to the accretionary prism through strike-slip faults and pull-apart basins that possibly form a lef-lateral poorly-active system inherited from a past tectonic phase, consistently with geodetic and seismologic data. - The anomalously cold interplate contact, consistent with a low interseismic coupling, is possibly due to fluid circulation within the shallow crustal aquifer or a depressed thermal structure of the oceanic crust related to the slow-spreading at the medio

  20. Fish assemblages in a western Iowa stream modified by grade control structures

    Science.gov (United States)

    Litvan, M.E.; Pierce, C.L.; Stewart, T.W.; Larson, C.J.

    2008-01-01

    Over 400 riprap grade control structures (GCSs) have been built in streams of western Iowa to reduce erosion and protect bridges, roads, and farmland. In conjunction with a companion study evaluating fish passage over GCSs in Turkey Creek, we evaluated the differences in fish assemblage and habitat characteristics in reaches immediately downstream from GCSs (GCS sites) and reaches at least 1 km from any GCS (non-GCS sites). The GCS sites were characterized by greater proportions of pool habitat, maximum depths, fish biomass, and abundance of juvenile largemouth bass Micropterus salmoides than were non-GCS sites. Index of biotic integrity (IBI) scores were poor or fair (structures is vital to the conservation and management of fish assemblages in this and other regions where GCSs or similar structures are used. ?? Copyright by the American Fisheries Society 2008.

  1. Effects of forest conversion on the assemblages' structure of aquatic insects in subtropical regions

    Directory of Open Access Journals (Sweden)

    Tiago R.N. Bertaso

    2015-03-01

    Full Text Available The effects of forest conversion to agricultural land uses on assemblages of aquatic insects were analyzed in subtropical streams. Organisms and environmental variables were collected in six low-order streams: three streams located in a forested area, and three in areas converted to agricultural land uses. We expected that the aquatic insects' assemblage attributes would be significantly affected by forest conversion, as well as by environmental variables. Streams in converted areas presented lower species richness, abundance and proportion of sensitive insect taxa. The ANOSIM test evidenced strong difference in EPT assemblage structure between streams of forested and converted areas. The ISA test evidenced several EPT genera with high specificity to streams in forested areas and only one genus related to streams in converted areas. Thus, the impacts of the conversion of forested area to agricultural land uses have significantly affected the EPT assemblages, while environmental variables were not affected. We suggest that the effects detected can be influenced by two processes related to vegetation cover: i lower input of allochthonous material, and ii increased input of fine sediments in streams draining converted areas.

  2. Coastal Upwelling Drives Intertidal Assemblage Structure and Trophic Ecology

    OpenAIRE

    Reddin, Carl J.; Felipe Docmac; Nessa E O'Connor; Bothwell, John H; Chris Harrod

    2015-01-01

    Similar environmental driving forces can produce similarity among geographically distant ecosystems. Coastal oceanic upwelling, for example, has been associated with elevated biomass and abundance patterns of certain functional groups, e.g., corticated macroalgae. In the upwelling system of Northern Chile, we examined measures of intertidal macrobenthic composition, structure and trophic ecology across eighteen shores varying in their proximity to two coastal upwelling centres, in a hierarchi...

  3. 3-D Magnetotelluric Investigations for geothermal exploration in Martinique (Lesser Antilles). Characteristic Deep Resistivity Structures, and Shallow Resistivity Distribution Matching Heliborne TEM Results

    CERN Document Server

    Coppo, Nicolas; Girard, Jean-François; Wawrzyniak, Pierre; Hautot, Sophie; Tarits, Pascal; Jacob, Thomas; Martelet, Guillaume; Mathieu, Francis; Gadalia, Alain; Bouchot, Vincent; Traineau, Hervé

    2015-01-01

    Within the framework of a global French program oriented towards the development of renewable energies, Martinique Island (Lesser Antilles, France) has been extensively investigated (from 2012 to 2013) through an integrated multi-methods approach, with the aim to define precisely the potential geothermal ressources, previously highlighted (Sanjuan et al., 2003). Amongst the common investigation methods deployed, we carried out three magnetotelluric (MT) surveys located above three of the most promising geothermal fields of Martinique, namely the Anses d'Arlet, the Montagne Pel{\\'e}e and the Pitons du Carbet prospects. A total of about 100 MT stations were acquired showing single or multi-dimensional behaviors and static shift effects. After processing data with remote reference, 3-D MT inversions of the four complex elements of MT impedance tensor without pre-static-shift correction, have been performed for each sector, providing three 3-D resistivity models down to about 12 to 30 km depth. The sea coast effe...

  4. Are changes in the structure of nematode assemblages reliable indicators of moderate petroleum contamination?

    Science.gov (United States)

    Leite, Daniel Silva; Sandrini-Neto, Leonardo; Camargo, Manuela Zeglin; Thomas, Micheli Cristina; Lana, Paulo C

    2014-06-15

    This study assesses through a multiple before-after-control-impact (MBACI) design the effects of diesel oil on the structure of nematode assemblages in unvegetated tidal flats of a subtropical estuary. Oil-exposed treatments were contrasted with controls for a duration of four successive days before and after an experimental spill in three distinct areas of the Paranaguá Estuarine Complex (Southern Brazil). No significant differences were observed in nematode total density, number of taxa and the overall assemblage structure between the control and impact treatments from before to after the experimental spill. This reinforces the idea that, despite being good indicators of environmental stress, free-living marine nematodes are able to tolerate low concentrations of hydrocarbons and to survive in moderately contaminated areas. We also show that robust experimental designs are useful to avoid confounding expected natural variability with the effects of a mild impact. PMID:24820646

  5. Colony geometry and structural complexity of the endangered species Acropora cervicornis partly explains the structure of their associated fish assemblage.

    Science.gov (United States)

    Agudo-Adriani, Esteban A; Cappelletto, Jose; Cavada-Blanco, Francoise; Croquer, Aldo

    2016-01-01

    In the past decade, significant efforts have been made to describe fish-habitat associations. However, most studies have oversimplified actual connections between fish assemblages and their habitats by using univariate correlations. The purpose of this study was to identify the features of habitat forming corals that facilitate and influences assemblages of associated species such as fishes. For this we developed three-dimensional models of colonies of Acropora cervicornis to estimate geometry (length and height), structural complexity (i.e., volume, density of branches, etc.) and biological features of the colonies (i.e., live coral tissue, algae). We then correlated these colony characteristics with the associated fish assemblage using multivariate analyses. We found that geometry and complexity were better predictors of the structure of fish community, compared to other variables such as percentage of live coral tissue or algae. Combined, the geometry of each colony explained 40% of the variability of the fish assemblage structure associated with this coral species; 61% of the abundance and 69% of fish richness, respectively. Our study shows that three-dimensional reconstructions of discrete colonies of Acropora cervicornis provides a useful description of the colonial structural complexity and may explain a great deal of the variance in the structure of the associated coral reef fish community. This demonstration of the strongly trait-dependent ecosystem role of this threatened species has important implications for restoration and conservation efforts. PMID:27069801

  6. Shift in a large river fish assemblage: body-size and trophic structure dynamics.

    Directory of Open Access Journals (Sweden)

    Kyle J Broadway

    Full Text Available As the intensity and speed of environmental change increase at both local and global scales it is imperative that we gain a better understanding of the ecological implications of community shifts. While there has been substantial progress toward understanding the drivers and subsequent responses of community change (e.g. lake trophic state, the ecological impacts of food web changes are far less understood. We analyzed Wabash River fish assemblage data collected from 1974-2008, to evaluate temporal variation in body-size structure and functional group composition. Two parameters derived from annual community size-spectra were our major response variables: (1 the regression slope is an index of ecological efficiency and predator-prey biomass ratios, and (2 spectral elevation (regression midpoint height is a proxy for food web capacity. We detected a large assemblage shift, over at least a seven year period, defined by dramatic changes in abundance (measured as catch-per-unit-effort of the dominant functional feeding groups among two time periods; from an assemblage dominated by planktivore-omnivores to benthic invertivores. There was a concurrent increase in ecological efficiency (slopes increased over time following the shift associated with an increase in large-bodied low trophic level fish. Food web capacity remained relatively stable with no clear temporal trends. Thus, increased ecological efficiency occurred simultaneous to a compensatory response that shifted biomass among functional feeding groups.

  7. Spatial arrangement overrules environmental factors to structure native and non-native assemblages of synanthropic harvestmen.

    Science.gov (United States)

    Muster, Christoph; Meyer, Marc; Sattler, Thomas

    2014-01-01

    Understanding how space affects the occurrence of native and non-native species is essential for inferring processes that shape communities. However, studies considering spatial and environmental variables for the entire community - as well as for the native and non-native assemblages in a single study - are scarce for animals. Harvestmen communities in central Europe have undergone drastic turnovers during the past decades, with several newly immigrated species, and thus provide a unique system to study such questions. We studied the wall-dwelling harvestmen communities from 52 human settlements in Luxembourg and found the assemblages to be largely dominated by non-native species (64% of specimens). Community structure was analysed using Moran's eigenvector maps as spatial variables, and landcover variables at different radii (500 m, 1000 m, 2000 m) in combination with climatic parameters as environmental variables. A surprisingly high portion of pure spatial variation (15.7% of total variance) exceeded the environmental (10.6%) and shared (4%) components of variation, but we found only minor differences between native and non-native assemblages. This could result from the ecological flexibility of both, native and non-native harvestmen that are not restricted to urban habitats but also inhabit surrounding semi-natural landscapes. Nevertheless, urban landcover variables explained more variation in the non-native community, whereas coverage of semi-natural habitats (forests, rivers) at broader radii better explained the native assemblage. This indicates that some urban characteristics apparently facilitate the establishment of non-native species. We found no evidence for competitive replacement of native by invasive species, but a community with novel combination of native and non-native species. PMID:24595309

  8. Impacts of temperature on primary productivity and respiration in naturally structured macroalgal assemblages.

    Directory of Open Access Journals (Sweden)

    Leigh W Tait

    Full Text Available Rising global temperatures caused by human-mediated change has already triggered significant responses in organismal physiology, distribution and ecosystem functioning. Although the effects of rising temperature on the physiology of individual organisms are well understood, the effect on community-wide processes has remained elusive. The fixation of carbon via primary productivity is an essential ecosystem function and any shifts in the balance of primary productivity and respiration could alter the carbon balance of ecosystems. Here we show through a series of tests that respiration of naturally structured algal assemblages in southern New Zealand greatly increases with rising temperature, with implications for net primary productivity (NPP. The NPP of in situ macroalgal assemblages was minimally affected by natural temperature variation, possibly through photo-acclimation or temperature acclimation responses, but respiration rates and compensating irradiance were negatively affected. However, laboratory experiments testing the impacts of rising temperature on several photosynthetic parameters showed a decline in NPP, increasing respiration rates and increasing compensating irradiance. The respiration Q10 of laboratory assemblages (the difference in metabolic rates over 10°C averaged 2.9 compared to a Q10 of 2 often seen in other autotrophs. However, gross primary productivity (GPP Q10 averaged 2, indicating that respiration was more severely affected by rising temperature. Furthermore, combined high irradiance and high temperature caused photoinhibition in the laboratory, and resulted in 50% lower NPP at high irradiance. Our study shows that communities may be more severely affected by rising global temperatures than would be expected by responses of individual species. In particular, enhanced respiration rates and rising compensation points have the potential to greatly affect the carbon balance of macroalgal assemblages through declines in

  9. Spatial arrangement overrules environmental factors to structure native and non-native assemblages of synanthropic harvestmen.

    Directory of Open Access Journals (Sweden)

    Christoph Muster

    Full Text Available Understanding how space affects the occurrence of native and non-native species is essential for inferring processes that shape communities. However, studies considering spatial and environmental variables for the entire community - as well as for the native and non-native assemblages in a single study - are scarce for animals. Harvestmen communities in central Europe have undergone drastic turnovers during the past decades, with several newly immigrated species, and thus provide a unique system to study such questions. We studied the wall-dwelling harvestmen communities from 52 human settlements in Luxembourg and found the assemblages to be largely dominated by non-native species (64% of specimens. Community structure was analysed using Moran's eigenvector maps as spatial variables, and landcover variables at different radii (500 m, 1000 m, 2000 m in combination with climatic parameters as environmental variables. A surprisingly high portion of pure spatial variation (15.7% of total variance exceeded the environmental (10.6% and shared (4% components of variation, but we found only minor differences between native and non-native assemblages. This could result from the ecological flexibility of both, native and non-native harvestmen that are not restricted to urban habitats but also inhabit surrounding semi-natural landscapes. Nevertheless, urban landcover variables explained more variation in the non-native community, whereas coverage of semi-natural habitats (forests, rivers at broader radii better explained the native assemblage. This indicates that some urban characteristics apparently facilitate the establishment of non-native species. We found no evidence for competitive replacement of native by invasive species, but a community with novel combination of native and non-native species.

  10. Ground-Vegetation Clutter Affects Phyllostomid Bat Assemblage Structure in Lowland Amazonian Forest.

    Science.gov (United States)

    Marciente, Rodrigo; Bobrowiec, Paulo Estefano D; Magnusson, William E

    2015-01-01

    Vegetation clutter is a limiting factor for bats that forage near ground level, and may determine the distribution of species and guilds. However, many studies that evaluated the effects of vegetation clutter on bats have used qualitative descriptions rather than direct measurements of vegetation density. Moreover, few studies have evaluated the effect of vegetation clutter on a regional scale. Here, we evaluate the influence of the physical obstruction of vegetation on phyllostomid-bat assemblages along a 520 km transect in continuous Amazonian forest. We sampled bats using mist nets in eight localities during 80 nights (3840 net-hours) and estimated the ground-vegetation density with digital photographs. The total number of species, number of animalivorous species, total number of frugivorous species, number of understory frugivorous species, and abundance of canopy frugivorous bats were negatively associated with vegetation clutter. The bat assemblages showed a nested structure in relation to degree of clutter, with animalivorous and understory frugivorous bats distributed throughout the vegetation-clutter gradient, while canopy frugivores were restricted to sites with more open vegetation. The species distribution along the gradient of vegetation clutter was not closely associated with wing morphology, but aspect ratio and wing load differed between frugivores and animalivores. Vegetation structure plays an important role in structuring assemblages of the bats at the regional scale by increasing beta diversity between sites. Differences in foraging strategy and diet of the guilds seem to have contributed more to the spatial distribution of bats than the wing characteristics of the species alone. PMID:26066654

  11. Ground-Vegetation Clutter Affects Phyllostomid Bat Assemblage Structure in Lowland Amazonian Forest.

    Directory of Open Access Journals (Sweden)

    Rodrigo Marciente

    Full Text Available Vegetation clutter is a limiting factor for bats that forage near ground level, and may determine the distribution of species and guilds. However, many studies that evaluated the effects of vegetation clutter on bats have used qualitative descriptions rather than direct measurements of vegetation density. Moreover, few studies have evaluated the effect of vegetation clutter on a regional scale. Here, we evaluate the influence of the physical obstruction of vegetation on phyllostomid-bat assemblages along a 520 km transect in continuous Amazonian forest. We sampled bats using mist nets in eight localities during 80 nights (3840 net-hours and estimated the ground-vegetation density with digital photographs. The total number of species, number of animalivorous species, total number of frugivorous species, number of understory frugivorous species, and abundance of canopy frugivorous bats were negatively associated with vegetation clutter. The bat assemblages showed a nested structure in relation to degree of clutter, with animalivorous and understory frugivorous bats distributed throughout the vegetation-clutter gradient, while canopy frugivores were restricted to sites with more open vegetation. The species distribution along the gradient of vegetation clutter was not closely associated with wing morphology, but aspect ratio and wing load differed between frugivores and animalivores. Vegetation structure plays an important role in structuring assemblages of the bats at the regional scale by increasing beta diversity between sites. Differences in foraging strategy and diet of the guilds seem to have contributed more to the spatial distribution of bats than the wing characteristics of the species alone.

  12. Fish assemblage structure in tributaries of the Meia Ponte River, Goiás, Brazil

    OpenAIRE

    Afonso P. Fialho; Leandro G. Oliveira; Francisco L. Tejerina-Garro; Luiz C. Gomes

    2007-01-01

    This study was conducted in the Meia Ponte River basin, which is located in the Cerrado biome. The objective was to describe the structure of fish assemblages and to evaluate the results with the regard to the position of the tributaries (sampling stations) along the basin. This basin drains 35 municipalities of Goiás State. Springs of the Meia Ponte are located in the district of Itauçu (GO), in the Serra dos Brandões. Two sampling were conducted, one in the rainy season (March/2001) and ano...

  13. Late Quaternary changes in bat palaeobiodiversity and palaeobiogeography under climatic and anthropogenic pressure: new insights from Marie-Galante, Lesser Antilles

    Science.gov (United States)

    Stoetzel, Emmanuelle; Royer, Aurélien; Cochard, David; Lenoble, Arnaud

    2016-07-01

    Data on Lesser Antillean Late Quaternary fossil bat assemblages remains limited, leading to their general exclusion from studies focusing on Caribbean bat palaeobiodiversity and palaeobiogeography. Additionally, the role of climatic versus human pressure driving changes in faunal communities remains poorly understood. Here we describe a fossil bat assemblage from Blanchard Cave on Marie-Galante in the Lesser Antilles, which produced numerous bat remains from a well-dated, stratified context. Our study reveals the occurrence of at least 12 bat species during the Late Pleistocene and Early Holocene on Marie-Galante, whereas only eight species are currently known on the island. Among these 12 species, six are extirpated and one is extinct. Faunal changes within the Blanchard sequence indicate variations in Pleistocene bat species representation in the Lesser Antilles to have been influenced by climatic conditions, with "northern species" (Greater Antilles) favored during glacial conditions and "southern species" (southern Lesser Antilles) during interglacial events. However, few species disappeared at the end of the Late Pleistocene, with most of the extinction/extirpation events occurring during the Holocene. This pattern suggests human activities in the Lesser Antilles to have played a major role in bat turnover during the late Holocene.

  14. Patch-Scale Effects of Equine Disturbance on Arthropod Assemblages and Vegetation Structure in Subalpine Wetlands

    Science.gov (United States)

    Holmquist, Jeffrey G.; Schmidt-Gengenbach, Jutta; Ballenger, Elizabeth A.

    2014-06-01

    Assessments of vertebrate disturbance to plant and animal assemblages often contrast grazed versus ungrazed meadows or other larger areas of usage, and this approach can be powerful. Random sampling of such habitats carries the potential, however, for smaller, more intensely affected patches to be missed and for other responses that are only revealed at smaller scales to also escape detection. We instead sampled arthropod assemblages and vegetation structure at the patch scale (400-900 m2 patches) within subalpine wet meadows of Yosemite National Park (USA), with the goal of determining if there were fine-scale differences in magnitude and directionality of response at three levels of grazing intensity. Effects were both stronger and more nuanced than effects evidenced by previous random sampling of paired grazed and ungrazed meadows: (a) greater negative effects on vegetation structure and fauna in heavily used patches, but (b) some positive effects on fauna in lightly grazed patches, suggested by trends for mean richness and total and population abundances. Although assessment of disturbance at either patch or landscape scales should be appropriate, depending on the management question at hand, our patch-scale work demonstrated that there can be strong local effects on the ecology of these wetlands that may not be detected by comparing larger scale habitats.

  15. Relationship between anthropogenic sewage discharge, marsh structure and bird assemblages in an SW Atlantic saltmarsh.

    Science.gov (United States)

    Cardoni, D A; Isacch, J P; Fanjul, M E; Escapa, M; Iribarne, O O

    2011-03-01

    One of the main effects of urbanization on coastal areas is through the discharge of sewage, which increases nutrient concentrations in the receiving environment. Salt marshes, like other coastal marine environments, are limited by nutrients, mainly nitrogen, and thus increasing nutrient loadings to a marsh may have consequences on marsh characteristics. We evaluated how the effects of nutrient enrichment in the form of sewage input, affected the vegetation structure and bird assemblages in a Spartina alterniflora salt marsh system near Bahía Blanca, Argentina (39° 01' S - 56° 25' W). Surveys of nutrient concentration, vegetation and birds were made at three different distances from the sewage discharge source. The concentration of ammonium, phosphate, and nitrate and the percent organic matter was higher in marshes nearest to the sewage discharge source. Bird composition and abundance, and vegetation physiognomy changed along a gradient of nutrient concentration. The increased habitat complexity found near the areas of higher nutrient concentration was exploited by birds that use neighboring interior and coastal habitats, including Spartina densiflora marshes, freshwater marshes and upland shrubby habitats. Our results show that local increases of nutrient inputs directly changed the vegetation physiognomy, and indirectly the composition and abundance of bird assemblages. PMID:21227503

  16. Structure and functioning of Mediterranean lagoon fish assemblages: A key for the identification of water body types

    Science.gov (United States)

    Franco, Anita; Franzoi, Piero; Torricelli, Patrizia

    2008-09-01

    Knowledge on the structure and functioning variability of transitional water fish assemblages may help in finding out the main descriptors for identifying different water body types for which specific biological reference conditions can be reliably derived. Fish assemblages from 19 Mediterranean lagoons were therefore investigated by evaluating the variability of their structure and functioning, and by relating it to the lagoons' environmental features. Fish assemblage structure was measured by its species richness. Functioning was measured by categorizing fish species into functional categories (or guilds) according to their use of lagoon habitat, feeding and reproduction, and by defining the functional structure of fish assemblages as the relative number of species per guild in each lagoon. Mediterranean lagoons' fish assemblages were found to be more similar to each other in their functional structure than in the taxonomical composition, thus confirming a shared functional role of these environments for biological communities. Lagoon local features, such as the lagoon area, its habitat heterogeneity and average salinity, significantly affected the total species richness and the different use that fish make of the lagoon environment, hence playing a primary role in the assessment of these water body types. Latitude also influenced the variability of fish assemblages in the Mediterranean lagoons investigated, with particular regard to their functioning as feeding and reproductive grounds for fish. These results are compared with previous studies and, although this limited the investigation to structural aspects only, were found to confirm in part the previous results and also added new insights about the key factors affecting the functioning of transitional water systems.

  17. Scale insects from the Netherlands Antilles

    NARCIS (Netherlands)

    Reyne, A.

    1964-01-01

    The following species have been reported from the Netherlands’ Antilles: Margarodes formicarum Guilding, collected in 1884 or 1885 by Prof. W. F. R. Suringar in Curaçao; specimens in the State Museum of Natural History at Leiden. Protortonia cacti (Linn.), collected in 1756 by Daniel Rolander in St.

  18. Spatial variations in fish assemblage structure in a southeastern Brazilian reservoir.

    Science.gov (United States)

    Sanches, B O; Hughes, R M; Macedo, D R; Callisto, M; Santos, G B

    2016-02-01

    We assessed the fish assemblage structure and composition of Nova Ponte Reservoir (Araguari River, Upper Paraná Basin, Brazil). We observed significant differences in abundance (p = 0.0003), richness (p = 0.0005) and diversity (p = 0.02) between lacustrine and riverine zones of the reservoir. Nine species were significantly more abundant in the riverine region: Astyanax altiparanae, Astyanax gr. fasciatus, Galeocharax knerii, Hoplias intermedius, Hypostomus sp., Leporinus friderici, Leporinus obtusidens, Pimelodus maculatus and Schizodon nasutus. The results indicated a longitudinal gradient in the composition and abundance of fishes in Nova Ponte Reservoir, reinforcing the importance of freely flowing riverine reaches for conserving native neotropical ichthyofauna and reflecting the strong adaptation of these species to riverine systems. PMID:26909635

  19. Comparison of avian assemblage structures in two upper montane forests of the Cameroon volcanic line: lessons for bird conservation

    Czech Academy of Sciences Publication Activity Database

    Djomo Nana, E.; Sedláček, O.; Bayly, N.; Ferenc, M.; Albrecht, Tomáš; Reif, J.; Motombi, F. N.; Hořák, D.

    2014-01-01

    Roč. 23, č. 6 (2014), s. 1469-1484. ISSN 0960-3115 R&D Projects: GA ČR(CZ) GAP505/11/1617 Institutional support: RVO:68081766 Keywords : Abundance-range size relationship * Assemblage structure * Range-restricted species * Species richness * West-Central Africa Subject RIV: EG - Zoology Impact factor: 2.365, year: 2014

  20. Ecoregional, catchment, and reach-scale environmental factors shape functional-trait structure of stream fish assemblages

    Science.gov (United States)

    Patterns of association between functional traits and environmental gradients can improve understanding of species assemblage structure from local to regional scales, and therefore may be useful for natural resource management. We measured functional traits related to trophic ecology, habitat use, a...

  1. Structure and diversity of intertidal benthic diatom assemblages in contrasting shores: a case study from the Tagus estuary(1).

    Science.gov (United States)

    Ribeiro, Lourenço; Brotas, Vanda; Rincé, Yves; Jesus, Bruno

    2013-04-01

    The structure of intertidal benthic diatoms assemblages in the Tagus estuary was investigated during a 2-year survey, carried out in six stations with different sediment texture. Nonparametric multivariate analyses were used to characterize spatial and temporal patterns of the assemblages and to link them to the measured environmental variables. In addition, diversity and other features related to community physiognomy, such as size-class or life-form distributions, were used to describe the diatom assemblages. A total of 183 diatom taxa were identified during cell counts and their biovolume was determined. Differences between stations (analysis of similarity (ANOSIM), R = 0.932) were more evident than temporal patterns (R = 0.308) and mud content alone was the environmental variable most correlated to the biotic data (BEST, ρ = 0.863). Mudflat stations were typically colonized by low diversity diatom assemblages (H' ~ 1.9), mainly composed of medium-sized motile epipelic species (250-1,000 μm(3) ), that showed species-specific seasonal blooms (e.g., Navicula gregaria Donkin). Sandy stations had more complex and diverse diatom assemblages (H' ~ 3.2). They were mostly composed by a large set of minute epipsammic species (<250 μm(3) ) that, generally, did not show temporal patterns. The structure of intertidal diatom assemblages was largely defined by the interplay between epipelon and epipsammon, and its diversity was explained within the framework of the Intermediate Disturbance Hypothesis. However, the spatial distribution of epipelic and epipsammic life-forms showed that the definition of both functional groups should not be over-simplified. PMID:27008515

  2. Changes in canopy structure and ant assemblages affect soil ecosystem variables as a foundation species declines

    OpenAIRE

    Ellison, Aaron M.; Kendrick, J.A.; Classen, A.T.; Ribbons, R.R.

    2015-01-01

    The decline of Tsuga canadensis (eastern hemlock) – a foundation tree species – due to infestation by Adelges tsugae (hemlock woolly adelgid) or its complete removal from a stand by salvage logging dramatically affects associated faunal assemblages. Among these assemblages, species composition (richness and abundance) of ants increases rapidly as T. canadensis is lost from the stands. Because ants live and forage at the litter-soil interface, we hypothesized that environmental changes caused ...

  3. Does structural complexity determine the morphology of assemblages? An experimental test on three continents.

    Directory of Open Access Journals (Sweden)

    Heloise Gibb

    Full Text Available Understanding how species will respond to global change depends on our ability to distinguish generalities from idiosyncrasies. For diverse, but poorly known taxa, such as insects, species traits may provide a short-cut to predicting species turnover. We tested whether ant traits respond consistently to habitat complexity across geographically independent ant assemblages, using an experimental approach and baits. We repeated our study in six paired simple and complex habitats on three continents with distinct ant faunas. We also compared traits amongst ants with different foraging strategies. We hypothesised that ants would be larger, broader, have longer legs and more dorsally positioned eyes in simpler habitats. In agreement with predictions, ants had longer femurs and dorsally positioned eyes in simple habitats. This pattern was most pronounced for ants that discovered resources. Body size and pronotum width responded as predicted for experimental treatments, but were inconsistent across continents. Monopolising ants were smaller, with shorter femurs than those that occupied or discovered resources. Consistent responses for several traits suggest that many, but not all, aspects of morphology respond predictably to habitat complexity, and that foraging strategy is linked with morphology. Some traits thus have the potential to be used to predict the direction of species turnover, changes in foraging strategy and, potentially, evolution in response to changes in habitat structure.

  4. Cultural assemblages show nested structure in humans and chimpanzees but not orangutans.

    Science.gov (United States)

    Kamilar, Jason M; Atkinson, Quentin D

    2014-01-01

    The evolution of hominin culture is well-documented in the archeological and fossil record, but such a record is largely absent for nonhuman primates. An alternative approach to studying cultural evolution is to examine patterns of modern cultural variation. In this article we measure nestedness across human and great ape "cultural repertoires" to gain insight into the accumulation and maintenance of putative cultural diversity in these species. Cultural assemblages are nested if cultures with a small repertoire of traits tend to comprise a proper subset of those traits present in more complex cultures. This nesting will occur if some traits are sequentially gained or lost, which may be because of the differential dispersal or extinction of traits. Here we apply statistical tools from ecology to examine the degree of nestedness in four datasets documenting the presence or absence of specific cultural traits across indigenous human populations in North America and New Guinea. We then compare the human data to patterns observed for putative cultural traits in chimpanzee and orangutan populations. In both humans and chimpanzees, cultural diversity is highly nonrandom, showing significant nested structure for all of the datasets examined. We find no evidence for nestedness in the orangutan cultural data. These findings are consistent with a sequential "layering" of cultural diversity in humans and chimpanzees, but not orangutans. Such an interpretation implies that the traits required for sequential cultural evolution first appeared in the last common ancestor of chimpanzees and humans. PMID:24324143

  5. Spatiotemporal diversity, structure and trophic guilds of insect assemblages in a semi-arid Sabkha ecosystem

    Directory of Open Access Journals (Sweden)

    Haroun Chenchouni

    2015-03-01

    Full Text Available The current study highlights some knowledge on the diversity and structure of insect communities and trophic groups living in Sabkha Djendli (semi-arid area of Northeastern Algeria. The entomofauna was monthly sampled from March to November 2006 using pitfall traps at eight sites located at the vicinity of the Sabkha. Structural and diversity parameters (species richness, Shannon index, evenness were measured for both insect orders and trophic guilds. The canonical correspondence analysis (CCA was applied to determine how vegetation parameters (species richness and cover influence spatial and seasonal fluctuations of insect assemblages. The catches totalled 434 insect individuals classified into 75 species, 62 genera, 31 families and 7 orders, of which Coleoptera and Hymenoptera were the most abundant and constant over seasons and study stations. Spring and autumn presented the highest values of diversity parameters. Individual-based Chao-1 species richness estimator indicated 126 species for the total individuals captured in the Sabkha. Based on catch abundances, the structure of functional trophic groups was predators (37.3%, saprophages (26.7%, phytophages (20.5%, polyphages (10.8%, coprophages (4.6%; whereas in terms of numbers of species, they can be classified as phytophages (40%, predators (25.3%, polyphages (13.3%, saprophages (12%, coprophages (9.3%. The CCA demonstrated that phytophages and saprophages as well as Coleoptera and Orthoptera were positively correlated with the two parameters of vegetation, especially in spring and summer. While the abundance of coprophages was positively correlated with species richness of plants, polyphage density was positively associated with vegetation cover. The insect community showed high taxonomic and functional diversity that is closely related to diversity and vegetation cover in different stations of the wetland and seasons.

  6. Trophic structure and mercury biomagnification in tropical fish assemblages, Itenez River, Bolivia.

    Directory of Open Access Journals (Sweden)

    Marc Pouilly

    Full Text Available We examined mercury concentrations in three fish assemblages to estimate biomagnification rates in the Iténez main river, affected by anthropogenic activities, and two unperturbed rivers from the Iténez basin, Bolivian Amazon. Rivers presented low to moderate water mercury concentrations (from 1.25 ng L(-1 to 2.96 ng L(-1 and natural differences in terms of sediment load. Mercury biomagnification rates were confronted to trophic structure depicted by carbon and nitrogen stable isotopes composition (δ(15N; δ(13C of primary trophic sources, invertebrates and fishes. Results showed a slight fish contamination in the Iténez River compared to the unperturbed rivers, with higher mercury concentrations in piscivore species (0.15 µg g(-1 vs. 0.11 µg g(-1 in the unperturbed rivers and a higher biomagnification rate. Trophic structure analysis showed that the higher biomagnification rate in the Iténez River could not be attributed to a longer food chain. Nevertheless, it revealed for the Iténez River a higher contribution of periphyton to the diet of the primary consumers fish species; and more negative δ(13C values for primary trophic sources, invertebrates and fishes that could indicate a higher contribution of methanotrophic bacteria. These two factors may enhance methylation and methyl mercury transfer in the food web and thus, alternatively or complementarily to the impact of the anthropogenic activities, may explain mercury differences observed in fishes from the Iténez River in comparison to the two other rivers.

  7. Effects of grade control structures on the macroinvertebrate assemblage of an agriculturally impacted stream

    Science.gov (United States)

    Litvan, M.E.; Stewart, T.W.; Pierce, C.L.; Larson, C.J.

    2008-01-01

    Nearly 400 rock rip-rap grade control structures (hereafter GCS) were recently placed in streams of western Iowa, USA to reduce streambank erosion and protect bridge infrastructure and farmland. In this region, streams are characterized by channelized reaches, highly incised banks and silt and sand substrates that normally support low macroinvertebrate abundance and diversity. Therefore, GCS composed of rip-rap provide the majority of coarse substrate habitat for benthic macroinvertebrates in these streams. We sampled 20 sites on Walnut Creek, Montgomery County, Iowa to quantify macroinvertebrate assemblage characteristics (1) on GCS rip-rap and at sites located (2) 5-50 m upstream of GCS, (3) 5-50 m downstream of GCS and (4) at least 1 km from any GCS (five sites each). Macroinvertebrate biomass, numerical densities and diversity were greatest at sites with coarse substrates, including GCS sites and one natural riffle site and relatively low at remaining sites with soft substrates. Densities of macroinvertebrates in the orders Ephemeroptera, Trichoptera, Diptera, Coleoptera and Acariformes were abundant on GCS rip-rap. Increases in macroinvertebrate biomass, density and diversity at GCS may improve local efficiency of breakdown of organic matter and nutrient and energy flow, and provide enhanced food resources for aquatic vertebrates. However, lack of positive macroinvertebrate responses immediately upstream and downstream of GCS suggest that positive effects might be restricted to the small areas of streambed covered by GCS. Improved understanding of GCS effects at both local and ecosystem scales is essential for stream management when these structures are present. Copyright ?? 2007 John Wiley & Sons, Ltd.

  8. Herpetofaunal assemblage with special emphasis on community structure and spatiality in amphibians of Cauvery delta region, Tamil Nadu

    OpenAIRE

    Anukul Nath; Sanjoy Sutradhar; A. Kalai Mani; Vishnu Vijyan; Krishna Kumar; B. Laxmi Narayana; B. Naresh; G. Baburao; Sneha Dharwadkar; Gokul Krishnan; B Vinoth; R. Maniraj; D. Mahendar Reddy; D. Adi mallaiah; Kummari Swamy

    2012-01-01

    We studied the amphibian community structure, spatial overlap and herpetofaunal assemblage at Mannampandal, Tamil Nadu during October, 2010 to January, 2011. The survey methods involved careful visual estimation of amphibians in all the possible microhabitats present in the study area. Five different microhabitat categories were selected, viz., leaf litters, temporary water pools, tree holes, shrubs & grasses (ground vegetation), pathways, open floor & outer edges of buildings. We identified ...

  9. Ecomorphological patterns of the fish assemblage in a tropical floodplain: effects of trophic, spatial and phylogenetic structures

    OpenAIRE

    Edson Fontes de Oliveira; Erivelto Goulart; Luciani Breda; Carolina Viviana Minte-Vera; Luiz Ricardo de Souza Paiva; Melina Rizzato Vismara

    2010-01-01

    Ecomorphological patterns of the fish assemblage from the upper Paraná River floodplain, Brazil, were described and evaluated according to trophic (guilds), spatial (habitats) and phylogenetic (taxonomic distances) structures. The samples were obtained through the Long Term Research Project (LTER-CNPq/UEM/NUPELIA) in August and October 2001. Thirty-five species were analyzed from thirty-one morphological variables. Strong significant correlations (Mantel test) between morphology and trophic g...

  10. Assemblages' structure and activity of bacterioplankton in northern Adriatic Sea surface waters: a 3-year case study.

    Science.gov (United States)

    Celussi, Mauro; Bussani, Andrea; Cataletto, Bruno; Del Negro, Paola

    2011-01-01

    The bacterial community, both in terms of community structure (denaturing gradient gel electrophoresis fingerprinting) and activity (exoenzymatic hydrolysis of proteins, polysaccharides and phosphorylated molecules and leucine uptake), was investigated seasonally for 3 years (2004-2006) in a large-scale grid in the northern Adriatic Sea. A high variability characterized the spatial structure of bacterial assemblages and a scarce seasonality was found in all the nine studied stations. Bacterial communities were substantially diverse in the same season of the 3 years, in contrast to what was reported previously for oceanic sites. Assemblages were in general strongly affected by river inputs, especially in spring, when freshwater loads were higher. Finally, a close relationship was found between given assemblages and their patterns of degradation/production activities by applying a multivariate analysis (linear discriminant analysis) to the dataset. The high variability of bacterial community structures and patterns of activity may indicate an ecological response to the high dynamism that characterizes the basin both on a physical and on a biological basis. PMID:21091521

  11. Biodiversity assessment of the fishes of Saba Bank atoll, Netherlands Antilles.

    Directory of Open Access Journals (Sweden)

    Jeffrey T Williams

    Full Text Available Biodiversity surveys were conducted on Saba Bank, Netherlands Antilles, to assess ichthyofaunal richness and to compare with published surveys of other Caribbean localities. The primary objective was to estimate the total species richness of the Saba Bank ichthyofauna. A variety of sampling techniques was utilized to survey the fish species of both the visually accessible megafauna and the camouflaged and small-sized species comprising the cryptic ichthyofauna.Based on results presented herein, the number of species known on Saba Bank is increased from 42 previously known species to 270 species. Expected species-accumulation curves demonstrate that the current estimate of species richness of fishes for Saba Bank under represents the actual richness, and our knowledge of the ichthyofauna has not plateaued. The total expected fish-species richness may be somewhere between 320 and 411 species.The Saba Bank ichthyofaunal assemblage is compared to fish assemblages found elsewhere in the Caribbean. Despite the absence of shallow or emergent shore habitats like mangroves, Saba Bank ranks as having the eighth highest ichthyofaunal richness of surveyed localities in the Greater Caribbean. Some degree of habitat heterogeneity was evident. Fore-reef, patch-reef, and lagoonal habitats were sampled. Fish assemblages were significantly different between habitats. Species richness was highest on the fore reef, but 11 species were found only at lagoonal sites.A comprehensive, annotated list of the fishes currently known to occur on Saba Bank, Netherland Antilles, is provided and color photographs of freshly collected specimens are presented for 165 of the listed species of Saba Bank fishes to facilitate identification and taxonomic comparison with similar taxa at other localities. Coloration of some species is shown for the first time. Preliminary analysis indicates that at least six undescribed new species were collected during the survey and these are

  12. Diversity, distribution and population size structure of deep Mediterranean gorgonian assemblages (Menorca Channel, Western Mediterranean Sea)

    Science.gov (United States)

    Grinyó, Jordi; Gori, Andrea; Ambroso, Stefano; Purroy, Ariadna; Calatayud, Clara; Dominguez-Carrió, Carlos; Coppari, Martina; Lo Iacono, Claudio; López-González, Pablo J.; Gili, Josep-Maria

    2016-06-01

    Gorgonians are a key group of organisms in benthic marine communities with a wide bathymetric and geographical distribution. Although their presence on continental shelves and slopes has been known for more than 100 years, knowledge concerning the ecology of deep gorgonian species is still in a very preliminary stage. To overcome this situation, gorgonian assemblages located at 40-360 m depth were studied over a large geographical area on the continental shelf and upper slope of the Menorca Channel (Western Mediterranean Sea). A quantitative analysis of video transects recorded by a manned submersible and a remotely operated vehicle, were used to examine the diversity, distribution and demography of gorgonian species. Results showed high gorgonian diversity within this depth range (a total of nine species were observed) compared to Mediterranean coastal areas. Gorgonian assemblages on the continental shelf and upper slope were mostly monospecific (respectively 73% and 76% of occupied sampling units contained one single species), whereas shelf edge assemblages were highly multispecific (92% of occupied sampling units contained several species). This contrasts with the monospecificity of Mediterranean coastal gorgonian assemblages. Gorgonian populations on the continental shelf were mostly dominated by small colonies (88% of measured colonies) with few intermediate and large colonies (12% of measured colonies). In deeper areas small colonies were still dominant (60% of measured colonies), but intermediate and large colonies were much more abundant (40% of measured colonies). This suggests high recruitment rates on the continental shelf, but perturbations (trammel nets, long lines and strong storms) may limit the presence of intermediate and large colonies. Conversely, on the shelf edge and upper slope a more stable environment may allow colonies to reach larger dimensions. The identification and ecological characterization of these deep assemblages further extends

  13. Habitat structure is more important than nutrient supply in modifying mussel bed assemblage in an upwelling area of the Peruvian coast

    Science.gov (United States)

    Firstater, Fausto N.; Hidalgo, Fernando J.; Lomovasky, Betina J.; Ramos, Elmer; Gamero, Patricia; Iribarne, Oscar O.

    2011-06-01

    Upwelling intensity modifies coastal primary production and influences individual traits of habitat-forming species. Along the Peruvian coast, beds of the mytilid Perumytilus purpuratus provide structurally complex habitats that harbour many organisms. We predict that in the nutrient-rich system of Central Peru, the modification of structural complexity would have stronger effects on the Perumytilus community than nutrient addition. We experimentally examined the effects of nutrient addition on the Perumytilus-dominated assemblage and we evaluated the potential effect of varying shell size on the Perumytilus-dominated assemblage. Nutrient addition to the mussel bed with slow-release fertilizers caused no changes in the total macro- and microalgal biomass and did not affect abundances or composition of the assemblage. To explore the effect of structural complexity on the Perumytilus assemblage, we manipulated mussel size with experimental bags containing small and large individuals. Predators, grazers and mobile organisms were more abundant among smaller mussels, with smaller gap volume, whereas the barnacle Jehlius cirratus was more abundant on larger mussels. In conclusion, point-source nutrient addition to the mussel bed did not enhance primary production. However, the modification of structural characteristics related to mussel size induced changes in the faunal assemblage. Thus, it seems that in this nutrient-rich system, nutrient enhancement would not significantly affect Perumytilus and its assemblage, whereas structural habitat seems to play an important role in shaping this community.

  14. Cultural assemblages show nested structure in humans and chimpanzees but not orangutans

    OpenAIRE

    KAMILAR, JASON M; Atkinson, Quentin D.

    2013-01-01

    The evolution of culture is well-documented in the human archeological and fossil records, but equivalent data are absent for nonhuman primates. Here, we use modern variation to learn about processes of temporal evolution by measuring nestedness across human and great ape “cultural repertoires.” Cultural assemblages are nested if cultures with a small repertoire of traits tend to comprise a proper subset of traits present in more complex cultures. We find a significant degree of nestedness in...

  15. Shift in a Large River Fish Assemblage: Body-Size and Trophic Structure Dynamics

    OpenAIRE

    Kyle J Broadway; Pyron, Mark; Gammon, James R.; Brent A Murry

    2015-01-01

    As the intensity and speed of environmental change increase at both local and global scales it is imperative that we gain a better understanding of the ecological implications of community shifts. While there has been substantial progress toward understanding the drivers and subsequent responses of community change (e.g. lake trophic state), the ecological impacts of food web changes are far less understood. We analyzed Wabash River fish assemblage data collected from 1974-2008, to evaluate t...

  16. Environmental Controls on River Assemblages at the Regional Scale: An Application of the Elements of Metacommunity Structure Framework.

    Directory of Open Access Journals (Sweden)

    Jonathan D Tonkin

    Full Text Available Understanding factors that structure regional biodiversity is important for linking ecological and biogeographic processes. Our objective was to explore regional patterns in riverine benthic invertebrate assemblages in relation to their broad positioning along the river network and examine differences in composition, biodiversity (alpha and beta diversity, and environmental drivers. We up-scaled methods used to examine patterns in metacommunity structure (Elements of Metacommunity Structure framework to examine faunal distribution patterns at the regional extent for 168 low-mountain stream invertebrate assemblages in central Germany. We then identified the most influential environmental factors using boosted regression trees. Faunal composition patterns were compartmentalised (Clementsian or quasi-Clementsian, with little difference from headwaters to large rivers, potentially reflecting the regional scale of the study, by crossing major catchment boundaries and incorporating different species pools. While idealised structures did not vary, environmental drivers of composition varied considerably between river sections and with alpha diversity. Prediction was substantially weaker, and the importance of space was greater, in large rivers compared to other sections suggesting a weakening in species sorting downstream. Further, there was a stronger transition in composition than for alpha diversity downstream. The stronger links with regional faunal composition than with richness further emphasises the importance of considering the alternative ways in which anthropogenic stressors are operating to affect biodiversity patterns. Our approach allowed bridging the gap between local (or metacommunity and regional scales, providing key insights into drivers of regional biodiversity patterns.

  17. Environmental Controls on River Assemblages at the Regional Scale: An Application of the Elements of Metacommunity Structure Framework.

    Science.gov (United States)

    Tonkin, Jonathan D; Sundermann, Andrea; Jähnig, Sonja C; Haase, Peter

    2015-01-01

    Understanding factors that structure regional biodiversity is important for linking ecological and biogeographic processes. Our objective was to explore regional patterns in riverine benthic invertebrate assemblages in relation to their broad positioning along the river network and examine differences in composition, biodiversity (alpha and beta diversity), and environmental drivers. We up-scaled methods used to examine patterns in metacommunity structure (Elements of Metacommunity Structure framework) to examine faunal distribution patterns at the regional extent for 168 low-mountain stream invertebrate assemblages in central Germany. We then identified the most influential environmental factors using boosted regression trees. Faunal composition patterns were compartmentalised (Clementsian or quasi-Clementsian), with little difference from headwaters to large rivers, potentially reflecting the regional scale of the study, by crossing major catchment boundaries and incorporating different species pools. While idealised structures did not vary, environmental drivers of composition varied considerably between river sections and with alpha diversity. Prediction was substantially weaker, and the importance of space was greater, in large rivers compared to other sections suggesting a weakening in species sorting downstream. Further, there was a stronger transition in composition than for alpha diversity downstream. The stronger links with regional faunal composition than with richness further emphasises the importance of considering the alternative ways in which anthropogenic stressors are operating to affect biodiversity patterns. Our approach allowed bridging the gap between local (or metacommunity) and regional scales, providing key insights into drivers of regional biodiversity patterns. PMID:26270550

  18. Variability in the Structure of Phytoplankton Assemblages in relation to Human Disturbance in Southern Coast of Tunisia

    Directory of Open Access Journals (Sweden)

    Lotfi Mabrouk

    2014-01-01

    Full Text Available We investigated the impact of industrial effluents on phytoplankton assemblage in southern Tunisia (Skhira. We specifically addressed changes in microalgae composition caused by this anthropogenic interference. A hierarchical sampling design was used to compare planktonic microalgae structure between one disturbed station and one control station. Samples were collected by scuba diving at 5 m depth in August 2012. A total of 76 microalgae taxa were identified. Dinoflagellates abundance was low in the disturbed station, especially Gonyaulacales and Prorocentrales due to P-limitation, whereas diatoms and cyanobacteria abundance were low in control station which is characterized by Si-limitation.

  19. Stable isotopes document the trophic structure of a deep-sea cephalopod assemblage including giant octopod and giant squid

    OpenAIRE

    Cherel, Y.; Ridoux, V.; Spitz, J.; RICHARD, P

    2009-01-01

    Although deep-sea cephalopods are key marine organims, their feeding ecology remains essentially unknown. Here, we report for the first time the trophic structure of an assemblage of these animals (19 species) by measuring the isotopic signature of wings of their lower beaks, which accumulated in stomachs of stranded sperm whales. Overall, the species encompassed a narrow range in δ13C values (1.7‰), indicating that they lived in closely related and overlapping habitats. δ13C values can be in...

  20. Patterns of Assemblage Structure Indicate a Broader Conservation Potential of Focal Amphibians for Pond Management.

    Science.gov (United States)

    Soomets, Elin; Rannap, Riinu; Lõhmus, Asko

    2016-01-01

    Small freshwater ponds host diverse and vulnerable biotic assemblages but relatively few conspicuous, specially protected taxa. In Europe, the amphibians Triturus cristatus and Pelobates fuscus are among a few species whose populations have been successfully restored using pond restoration and management activities at the landscape scale. In this study, we explored whether the ponds constructed for those two target species have wider conservation significance, particularly for other species of conservation concern. We recorded the occurrence of amphibians and selected aquatic macro-invertebrates (dragonflies; damselflies; diving beetles; water scavenger beetles) in 66 ponds specially constructed for amphibians (up to 8 years post construction) and, for comparison, in 100 man-made ponds (created by local people for cattle or garden watering, peat excavation, etc.) and 65 natural ponds in Estonia. We analysed nestedness of the species assemblages and its dependence on the environment, and described the co-occurrence patterns between the target amphibians and other aquatic species. The assemblages in all ponds were significantly nested, but the environmental determinants of nestedness and co-occurrence of particular species differed among pond types. Constructed ponds were most species-rich irrespective of the presence of the target species; however, T. cristatus was frequent in those ponds and rare elsewhere, and it showed nested patterns in every type of pond. We thus conclude that pond construction for the protected amphibians can serve broader habitat conservation aims in the short term. However, the heterogeneity and inconsistent presence of species of conservation concern observed in other types of ponds implies that long-term perspectives on pond management require more explicit consideration of different habitat and biodiversity values. We also highlight nestedness analysis as a tool that can be used for the practical task of selecting focal species for

  1. Application of "taxocene surrogation" and "taxonomic sufficiency" concepts to fish farming environmental monitoring. Comparison of BOPA index versus polychaete assemblage structure.

    Science.gov (United States)

    Aguado-Giménez, F; Gairín, J I; Martinez-Garcia, E; Fernandez-Gonzalez, V; Ballester Moltó, M; Cerezo-Valverde, J; Sanchez-Jerez, P

    2015-02-01

    "Taxocene surrogation" and "taxonomic sufficiency" concepts were applied to the monitoring of soft bottoms macrobenthic assemblages influenced by fish farming following two approaches. Polychaete assemblage evaluation through multivariate analysis and the benthic index BOPA were compared. Six fish farms along the Spanish Mediterranean coast were monitored. Polychaete assemblage provided a suitable picture of the impact gradient, being correlated with total free sulphides. BOPA did not support the impact gradient described by the polychaete assemblage, providing erroneous categorizations. The inclusion of several polychaete families, which were locally identified as indicative of affection to recalculate BOPA, resulted in an improved diagnosis and correlation with the impact gradient. Nevertheless, frequent misclassifications occurred. These results suggest that the structure of polychaete families, sulphides and granulometry conform an appropriate strategy for fish farming monitoring. Biotic indices need to be specifically designed for concrete activities, and regionally validated, because of the environmental plasticity of benthic invertebrates. PMID:25460059

  2. Topographical and hydrographical impacts on the structure of microphytoplankton assemblages on the Abrolhos Bank region, Brazil

    Science.gov (United States)

    Susini-Ribeiro, Sylvia M. M.; Pompeu, Mayza; Gaeta, Salvador A.; de Souza, Júlia S. D.; Masuda, Laura S. D.

    2013-11-01

    This study was conducted at the Abrolhos Bank (15°60‧-21°30‧S; 37°00‧-40°30‧W), Brazil, in July and August 2007, to evaluate the topographic and hydrographic influences on microphytoplankton composition and relative abundance. Net phytoplankton was collected from the top 200 m of the water column to assess diversity proxies (species richness, Shannon index, dominance and equitability) and compared with thermohaline, nutrient and chlorophyll profiles. A total of 326 taxa occurred in the area. Patterns in spatial distribution of microphytoplankton assemblages were two-fold: a north-south gradient linked to variations in temperature and nitrite, and a coast-offshore gradient associated with the depth of the mixed layer and the Brunt-Väisälä maximum frequency. Microphytoplankton assemblages were typical of tropical oligotrophic environments. However, the inshore community found on the Abrolhos Bank was enriched by bottom dwelling, large-sized cells ressuspended from local sediments as a result of the highly dynamic coastal circulation. Species diversity was high in oceanic sites where water column stability as measured by the Brunt-Väisälä frequency achieved its maxima, but high values of ecological indexes were also found in the southern part of the study area influenced by bottom intrusions of nutrient-rich oceanic waters, giving support to the notion that phytoplankton diversity increases at intermediate levels of environmental disturbance.

  3. Composition, structural characteristics and temporal patterns of fish assemblages in non-tidal Mediterranean lagoons: A case study

    Science.gov (United States)

    Maci, S.; Basset, A.

    2009-08-01

    The importance of transitional water ecosystems as nursery habitats and feeding grounds for fish species is well-known. Detailed studies of colonization patterns of fish guilds in response to biotic and abiotic drivers are however unevenly distributed among ecosystem types. We address here the temporal variability of fish assemblages in small non-tidal lagoons in the Mediterranean basin. The study was carried out at the Acquatina lagoon (Lecce, Italy) where four stations, situated in two habitat types along a confinement gradient, were sampled twice per month for one year with fyke nets. Forty-five taxa ranging across 20 families were collected, with the most abundant species, Atherina boyeri, accounting for more than 95% of total abundance. Pooling all species together (excluding sand smelt), the structural features of the assemblage, relative abundance of families, and abundance of individual species all showed significant temporal patterns. Mean abundance peaked in Summer and Autumn and fell in Winter, whereas taxonomic richness and diversity were highest in Summer and lowest in Spring. Within the fish assemblage, multivariate ordination showed temporal segregation of species belonging to the same family or genus and expected to be functionally similar, suggesting that they avoid competition for space and resources by timing inward migration and peak occurrence differently. Of the environmental driving forces, which also showed temporal patterns of variation, salinity was the main factor affecting the distribution of individuals and species. The catch of young individuals of several marine species confirmed the role of this small lagoon as a nursery and feeding area, and emphasized the need for further studies.

  4. Changes in canopy structure and ant assemblages affect soil ecosystem variables as a foundation species declines

    DEFF Research Database (Denmark)

    Kendrick, Joseph A.; Ribbons, Relena Rose; Classen, Aimee Taylor;

    2015-01-01

    (richness and abundance) of ants increases rapidly as T. canadensis is lost from the stands. Because ants live and forage at the litter-soil interface, we hypothesized that environmental changes caused by hemlock loss (e.g., increased light and warmth at the forest floor, increased soil pH) and shifts in...... ant species composition would interact to alter soil ecosystem variables. In the Harvard Forest Hemlock Removal Experiment (HF-HeRE), established in 2003, T. canadensis in large plots were killed in place or logged and removed to mimic adelgid infestation or salvage harvesting, respectively. In 2006......, we built ant exclosure subplots within all of the canopy manipulation plots to examine direct and interactive effects of canopy change and ant assemblage composition on soil and litter variables. Throughout HF-HeRE, T. canadensis was colonized by the adelgid in 2009, and the infested trees are now...

  5. Study of Endemic and Threatened Fish Species Diversity and its Assemblage Structure from Northern Western Ghats, Maharashtra, India

    Directory of Open Access Journals (Sweden)

    Tejas S. Patil

    2015-01-01

    Full Text Available The present investigation undertakes to study endemic and threatened fish species and its assemblage structure from rivers of Kolhapur district for the period July-2012 to December-2014. The study area is situated in the extreme Southern part of Maharashtra state. It contributes much more part of Western Ghats. A total of 23 species belonging to 7 families and 19 genera were reported. In which 9 species are threatened and 20 species are endemic to Western Ghats, we found that 6 species are threatened as well as endemic. Puntius sahyadriensis, Nemacheilus anguilla, Pterocryptis wynaadensis and Glyptothorax trewavasae are first time reported from Kolhapur district. High Shannon diversity index shows considerable variation and ranges from 1.34-2.43. Margalef’s diversity index and Evenness index for each sampling site were also recorded. The similarity in cluster analysis from nearby sampling site along the river has similar faunal assemblage. The problems related to various threats for aquatic biodiversity and conservation management strategies have been discussed.

  6. Community structure and decadal changes in macrozoobenthic assemblages in Lake Poyang, the largest freshwater lake in China

    Directory of Open Access Journals (Sweden)

    Cai Y. J.

    2014-01-01

    Full Text Available Lake Poyang is the largest freshwater lake in China and contains unique and diverse biota within the Yangtze floodplain ecosystem. However, knowledge of its macrozoobenthic assemblages remains inadequate. To characterize the current community structure of these assemblages and to portray their decadal changes, quarterly investigations were conducted at 15 sites from February to November 2012. A total of 42 taxa were recorded, and Corbicula fluminea, Limnoperna fortunei, Gammaridae sp., Nephtys polybranchia, Polypedilum scalaenum and Branchiura sowerbyi were found to dominate the community in terms of abundance. The bivalves Corbicula fluminea, Lamprotula rochechouarti, Arconaia lanceolata and Lamprotula caveata dominated the community in biomass due to their large body size. The mean abundance of the total macrozoobenthos varied from 48 to 920 ind·m-2, the mean biomass ranged from 28 to 428 g·m-2. The substrate type affected strongly the abundance, biomass, and diversity of the macrozoobenthos, with muddy sand substrates showing the highest values. Compared with historical data, remarkable changes were observed in the abundance of macrozoobenthos and the identity of the dominant species. The mean total abundance decreased from 724 ind·m-2 in 1992 to 228 ind·m-2 in 2012. The dominant species have shifted dramatically. Large unionids were dominant before 1998, whereas pollution-tolerant species (e.g., Branchiura sowerbyi increased in dominance after 2008. Our findings should have implications for the conservation of the benthic biodiversity of this large Yangtze-connected lake.

  7. 76 FR 68039 - Federal Acquisition Regulation; Successor Entities to the Netherlands Antilles

    Science.gov (United States)

    2011-11-02

    ... Regulation; Successor Entities to the Netherlands Antilles AGENCIES: Department of Defense (DoD), General... status of the islands that comprised the Netherlands Antilles. DATES: Effective Date: November 2, 2011.... Background The Netherlands Antilles was designated as a beneficiary country under the Caribbean...

  8. Strange Assemblage

    Directory of Open Access Journals (Sweden)

    David Robert Cole

    2014-08-01

    Full Text Available This paper contends that the power of Deleuze & Guattari’s (1988 notion of assemblage as theorised in 1000 Plateaus can be normalised and reductive with reference to its application to any social-cultural context where an open system of dynamic and fluid elements are located. Rather than determining the assemblage in this way, this paper argues for an alternative conception of ‘strange assemblage’ that must be deliberately and consciously created through rigorous and focused intellectual, creative and philosophical work around what makes assemblages singular. The paper will proceed with examples of ‘strange assemblage’ taken from a film by Peter Greenaway (A Zed and 2 Noughts; the film ‘Performance’; educational research with Sudanese families in Australia; the book, Bomb Culture by Jeff Nuttall (1970; and the band Hawkwind. Fittingly, these elements are themselves chosen to demonstrate the concept of ‘strange assemblage’, and how it can be presented. How exactly the elements of a ‘strange assemblage’ come together and work in the world is unknown until they are specifically elaborated and created ‘in the moment’. Such spontaneous methodology reminds us of the 1960s ‘Happenings’, the Situationist International and Dada/Surrealism. The difference that will be opened up by this paper is that all elements of this ‘strange assemblage’ cohere in terms of a rendering of ‘the unacceptable.'

  9. La crise sociale aux Antilles françaises

    Directory of Open Access Journals (Sweden)

    Justin Daniel

    2009-03-01

    Full Text Available La crise sociale qui a récemment secoué les Antilles françaises consacre le retour de la « question sociale » sur les scènes politiques insulaires. Elle s’est également traduite par un dessaisissement du personnel politique dont la parole est devenue inaudible, et une montée en puissance de la société civile. Loin d’avoir réglé les problèmes structurels, elle témoigne cependant d’une évolution significative des rapports entre l’outre-mer et l’Hexagone.The social crisis which recently shook the French West Indies legitimises the return of the “social question” on the insular political scenes. It also resulted in a withdrawal of the political personnel whose discourse became inaudible and in the emergence of civil society. Far from having resolved the structural problems, it reveals a significant change of the relationship between the overseas territories  and the Hexagon.

  10. Exploring the determinants of phylogenetic diversity and assemblage structure in conifers across temporal, spatial, and taxonomic scales

    DEFF Research Database (Denmark)

    Eiserhardt, Wolf L.; Borchsenius, Finn; Sandel, Brody Steven;

    have long-lasting effects on species pools and local assemblages. Integrating such long-term dynamics with short-term ecological processes in a common analytical framework is a major challenge of integrative biodiversity science. Phylogenetically informed diversity measures and palaeo-environmental......Composition, diversity, structure and function of modern plant communities are strongly related to the current environment, but they may also depend on past eco-evolutionary dynamics. For example, climate change can exert a strong influence on lineage diversification and niche evolution, and thus...... throughout the natural range of the group (269 TDWG3 “botanical countries”) to infer the effects of current and past climate . To explore the effects of taxonomic and spatial scale, we deconstruct the overall pattern into families and perform a fine-scale analysis for one particular lineage (the genus Pinus...

  11. Structuring of zooplankton and fish larvae assemblages in a freshwater-influenced Greenlandic fjord- influence from hydrography and prey availability

    DEFF Research Database (Denmark)

    Swalethorp, Rasmus; Malanski, Evandro; Munk, Peter;

    2015-01-01

    The recent increase in temperature and freshwater runoff in the Arctic will influence the functioning of the plankton ecosystem and hence the life of the fish larvae residing in these areas. Here, we studied the strength of physical– biological linkages and the adaptability of individual larval...... fish species to changing hydrographical and feeding environments in a sub-Arctic area in Greenland. The study was carried out along a transect covering a wide range of physical conditions from the deep ocean to the icecap in the Godtha°bsfjord on the south-western Greenland coast. Along the transect......, we identified a series of distinct zooplankton and larval fish assemblages which showed linkage to water mass characteristics, to the presence of frontal structures and to availability of preferred prey. Spawning site location and water circulation was also likely to influence distributional patterns...

  12. Herpetofaunal assemblage with special emphasis on community structure and spatiality in amphibians of Cauvery delta region, Tamil Nadu

    Directory of Open Access Journals (Sweden)

    Anukul Nath

    2012-12-01

    Full Text Available We studied the amphibian community structure, spatial overlap and herpetofaunal assemblage at Mannampandal, Tamil Nadu during October, 2010 to January, 2011. The survey methods involved careful visual estimation of amphibians in all the possible microhabitats present in the study area. Five different microhabitat categories were selected, viz., leaf litters, temporary water pools, tree holes, shrubs & grasses (ground vegetation, pathways, open floor & outer edges of buildings. We identified 26 species of reptiles and 14 species of amphibians. There was a significant difference found among the amphibian species occupying in different microhabitats. Species diversity was calculated, Shanon-Wiener H'= 1.55. The high niche overlap was found between Duttaphrynus scaber and Uperodon systoma followed by Fejervarya sp. and Sphaerotheca breviceps. The present study on amphibian community is just a representation to show the microhabitat occupancy and adjustment by the amphibians in human settlements and competition among them as, spatial resource partitioning.

  13. Phytoplankton assemblage structure in and around a massive under-ice bloom in the Chukchi Sea

    Science.gov (United States)

    Laney, Samuel R.; Sosik, Heidi M.

    2014-07-01

    Standard and imaging flow cytometry were used to examine the composition of phytoplankton assemblages in and around a massive under-ice bloom in the Chukchi Sea in 2011. In the core of this bloom, roughly 100 km northwest of Hanna Shoal, diatoms represented roughly 87% of the water column carbon-specific biomass of phytoplankton, while nanophytoplankton contributed ~9%. Picoeukaryotes were also observed in this bloom, as were phycoerythrin-containing cells consistent with Synechococcus spp., but picophytoplankton, dinoflagellates, and prymnesiophytes each represented only ~1% of the blooms phytoplankton biomass. More broadly along this part of the Chukchi shelf, nanophytoplankton typically comprised a larger fraction of phytoplankton biomass in the water column, 22% on average but up to 82% at certain locations. Dinoflagellates and prymnesiophytes contributed at most 2% of water column biomass at any location and were most abundant in the deeper slope stations northeast of Hanna Shoal, east of the bloom. Picophytoplankton were most abundant in these deeper slope stations as well, and also in recently ice-free areas to the south around Hanna Shoal. These cell-derived estimates of phytoplankton carbon biomass, which were computed from imaging and standard cytometric observations of phytoplankton cell sizes and from published carbon:volume relationships, agree well with independent measurements of particulate organic carbon concentration from traditional biochemical assays.

  14. Structure and dynamics of the shark assemblage off Recife, Northeastern Brazil.

    Science.gov (United States)

    Afonso, André S; Andrade, Humber A; Hazin, Fábio H V

    2014-01-01

    Understanding the ecological factors that regulate elasmobranch abundance in nearshore waters is essential to effectively manage coastal ecosystems and promote conservation. However, little is known about elasmobranch populations in the western South Atlantic Ocean. An 8-year, standardized longline and drumline survey conducted in nearshore waters off Recife, northeastern Brazil, allowed us to describe the shark assemblage and to monitor abundance dynamics using zero-inflated generalized additive models. This region is mostly used by several carcharhinids and one ginglymostomid, but sphyrnids are also present. Blacknose sharks, Carcharhinus acronotus, were mostly mature individuals and declined in abundance throughout the survey, contrasting with nurse sharks, Ginglymostoma cirratum, which proliferated possibly due to this species being prohibited from all harvest since 2004 in this region. Tiger sharks, Galeocerdo cuvier, were mostly juveniles smaller than 200 cm and seem to use nearshore waters off Recife between January and September. No long-term trend in tiger shark abundance was discernible. Spatial distribution was similar in true coastal species (i.e. blacknose and nurse sharks) whereas tiger sharks were most abundant at the middle continental shelf. The sea surface temperature, tidal amplitude, wind direction, water turbidity, and pluviosity were all selected to predict shark abundance off Recife. Interspecific variability in abundance dynamics across spatiotemporal and environmental gradients suggest that the ecological processes regulating shark abundance are generally independent between species, which could add complexity to multi-species fisheries management frameworks. Yet, further research is warranted to ascertain trends at population levels in the South Atlantic Ocean. PMID:25010514

  15. Structure of Phoretic Mite Assemblages Across Subcortical Beetle Species at a Regional Scale.

    Science.gov (United States)

    Pfammatter, Jesse A; Coyle, David R; Gandhi, Kamal J K; Hernandez, Natalie; Hofstetter, Richard W; Moser, John C; Raffa, Kenneth F

    2016-02-01

    Mites associated with subcortical beetles feed and reproduce within habitats transformed by tree-killing herbivores. Mites lack the ability to independently disperse among these habitats, and thus have evolved characteristics that facilitate using insects as transport between resources. Studies on associations between mites and beetles have historically been beetle-centric, where an assemblage of mite species is characterized on a single beetle species. However, available evidence suggests there may be substantial overlap among mite species on various species of beetles utilizing similar host trees. We assessed the mite communities of multiple beetle species attracted to baited funnel traps in Pinus stands in southern Wisconsin, northern Arizona, and northern Georgia to better characterize mite dispersal and the formation of mite-beetle phoretic associations at multiple scales. We identified approximately 21 mite species totaling 10,575 individuals on 36 beetle species totaling 983 beetles. Of the mites collected, 97% were represented by eight species. Many species of mites were common across beetle species, likely owing to these beetles' common association with trees in the genus Pinus. Most mite species were found on at least three beetle species. Histiostoma spp., Iponemus confusus Lindquist, Histiogaster arborsignis Woodring and Trichouropoda australis Hirschmann were each found on at least seven species of beetles. While beetles had largely similar mite membership, the abundances of individual mite species were highly variable among beetle species within each sampling region. Phoretic mite communities also varied within beetle species between regions, notably for Ips pini (Say) and Ips grandicollis (Eichhoff). PMID:26496952

  16. Temporal variability of biodiversity patterns and trophic structure of estuarine macrobenthic assemblages along a gradient of metal contamination

    KAUST Repository

    Piló, D.

    2015-06-01

    The present study aimed to investigate the response of macrobenthic assemblages along a gradient of metal contamination using a combination of uni- and multivariate methods focusing on their composition, structure and function. A total of six sites were established based on a preliminary survey, which identified three areas with different levels of contamination. These areas were defined as slightly contaminated (SC), moderately contaminated (MC) and highly contaminated (HC). Each area comprised two sites, sampled in four sampling surveys (September 2012, February, May and October of 2013). To investigate the response of the macrobenthic assemblages the number of individuals (N), number of taxa (S), Shannon-Weaver diversity (H\\'), Pielou\\'s equitability (J\\') and different distance-based multivariate measures of β-diversity (complementarity) were analysed. β-diversity as turnover was also analysed together with spatial and temporal changes in the trophic structure. A clear gradient of increasing contamination was consistently detected, but comparisons with available sediment quality guidelines indicated that adverse biological effects may be expected in all areas. This result suggests measuring concentrations of contaminants in the sediment per se may be insufficient to establish a clear link between ecological patterns and the contamination of the system. Also it highlights the difficulty of identifying reference areas in highly urbanized and industrialized estuaries. Only multivariate analysis (dbRDA; both using the taxonomic and trophic composition) and β-diversity as turnover showed a consistent response to metal contamination. Higher heterogeneity, mainly due to contribution of rare species (i.e. species present in a single sampling period), was observed in the least contaminated area (SC), decreasing towards the HC. In terms of the trophic function, a shift from a dominance of carnivores in the SC to the dominance of deposit-feeding organisms (and

  17. Effects of grade control structures on fish passage, biological assemblages, and hydraulic environments in western Iowa streams: a multidisciplinary review

    Science.gov (United States)

    Thomas, J.T.; Culler, M.E.; Dermisis, D.C.; Pierce, Clay; Papanicolaou, A.N.; Stewart, T.W.; Larson, C.J.

    2011-01-01

    Land use changes and channelization of streams in the deep loess region of western Iowa have led to stream channel incision, altered flow regimes, increased sediment inputs, decreased habitat diversity and reduced lateral connectivity of streams and floodplains. Grade control structures (GCSs) are built in streams to prevent further erosion, protect infrastructure and reduce sediment loads. However, GCS can have a detrimental impact on fisheries and biological communities. We review three complementary biological and hydraulic studies on the effects of GCS in these streams. GCS with steep (≥1:4 rise : run) downstream slopes severely limited fish passage, but GCS with gentle slopes (≤1:15) allowed greater passage. Fish assemblages were dominated by species tolerant of degradation, and Index of Biotic Integrity (IBI) scores were indicative of fair or poor biotic integrity. More than 50% of fish species had truncated distributions. After modification of GCS to reduce slopes and permit increased passage, IBI scores increased and several species were detected further upstream than before modification. Total macroinvertebrate density, biomass and taxonomic diversity and abundance of ecologically sensitive taxa were greater at GCS than in reaches immediately upstream, downstream or ≥1 km from GCS. A hydraulic study confirmed results from fish passage studies; minimum depths and maximum current velocities at GCS with gentle slopes (≤1:15) were more likely to meet minimum criteria for catfish passage than GCS with steeper slopes. Multidisciplinary approaches such as ours will increase understanding of GCS-associated factors influencing fish passage, biological assemblage structure and other ecological relationships in streams.

  18. Temporal variability of biodiversity patterns and trophic structure of estuarine macrobenthic assemblages along a gradient of metal contamination

    Science.gov (United States)

    Piló, D.; Pereira, F.; Carriço, A.; Cúrdia, J.; Pereira, P.; Gaspar, M. B.; Carvalho, S.

    2015-12-01

    The present study aimed to investigate the response of macrobenthic assemblages along a gradient of metal contamination using a combination of uni- and multivariate methods focusing on their composition, structure and function. A total of six sites were established based on a preliminary survey, which identified three areas with different levels of contamination. These areas were defined as slightly contaminated (SC), moderately contaminated (MC) and highly contaminated (HC). Each area comprised two sites, sampled in four sampling surveys (September 2012, February, May and October of 2013). To investigate the response of the macrobenthic assemblages the number of individuals (N), number of taxa (S), Shannon-Weaver diversity (H‧), Pielou's equitability (J‧) and different distance-based multivariate measures of β-diversity (complementarity) were analysed. β-diversity as turnover was also analysed together with spatial and temporal changes in the trophic structure. A clear gradient of increasing contamination was consistently detected, but comparisons with available sediment quality guidelines indicated that adverse biological effects may be expected in all areas. This result suggests measuring concentrations of contaminants in the sediment per se may be insufficient to establish a clear link between ecological patterns and the contamination of the system. Also it highlights the difficulty of identifying reference areas in highly urbanized and industrialized estuaries. Only multivariate analysis (dbRDA; both using the taxonomic and trophic composition) and β-diversity as turnover showed a consistent response to metal contamination. Higher heterogeneity, mainly due to contribution of rare species (i.e. species present in a single sampling period), was observed in the least contaminated area (SC), decreasing towards the HC. In terms of the trophic function, a shift from a dominance of carnivores in the SC to the dominance of deposit-feeding organisms (and

  19. Structure and dynamics of the shark assemblage off Recife, Northeastern Brazil.

    Directory of Open Access Journals (Sweden)

    André S Afonso

    Full Text Available Understanding the ecological factors that regulate elasmobranch abundance in nearshore waters is essential to effectively manage coastal ecosystems and promote conservation. However, little is known about elasmobranch populations in the western South Atlantic Ocean. An 8-year, standardized longline and drumline survey conducted in nearshore waters off Recife, northeastern Brazil, allowed us to describe the shark assemblage and to monitor abundance dynamics using zero-inflated generalized additive models. This region is mostly used by several carcharhinids and one ginglymostomid, but sphyrnids are also present. Blacknose sharks, Carcharhinus acronotus, were mostly mature individuals and declined in abundance throughout the survey, contrasting with nurse sharks, Ginglymostoma cirratum, which proliferated possibly due to this species being prohibited from all harvest since 2004 in this region. Tiger sharks, Galeocerdo cuvier, were mostly juveniles smaller than 200 cm and seem to use nearshore waters off Recife between January and September. No long-term trend in tiger shark abundance was discernible. Spatial distribution was similar in true coastal species (i.e. blacknose and nurse sharks whereas tiger sharks were most abundant at the middle continental shelf. The sea surface temperature, tidal amplitude, wind direction, water turbidity, and pluviosity were all selected to predict shark abundance off Recife. Interspecific variability in abundance dynamics across spatiotemporal and environmental gradients suggest that the ecological processes regulating shark abundance are generally independent between species, which could add complexity to multi-species fisheries management frameworks. Yet, further research is warranted to ascertain trends at population levels in the South Atlantic Ocean.

  20. Frogs of the genus Eleutherodactylus in the Lesser Antilles

    NARCIS (Netherlands)

    Schwartz, Albert

    1967-01-01

    The Lesser Antilles consist of those West Indian islands which extend from the Anegada Passage in the north to Grenada in the south.¹) These islands are nomenclatorially divided into two major groups: 1) The Leeward Islands, including Sombrero, Anguilla, St. Martin, St.-Barthélemy [= St. Barts], Sab

  1. Situation Reports--Bahamas, Brasil, Guatemala, Netherlands Antilles (Curacao), Uruguay.

    Science.gov (United States)

    International Planned Parenthood Federation, London (England).

    Data relating to population and family planning in four foreign countries are presented in these situation reports. Countries included are Bahamas, Guatemala, Netherlands Antilles (Curacao), and Uruguay. Information is provided under two topics, general background and family planning situation, where appropriate and if it is available. General…

  2. Preliminary Assessment of Sponge Biodiversity on Saba Bank, Netherlands Antilles

    NARCIS (Netherlands)

    R.W. Thacker; M.C. Díaz; N.J. de Voogd; R.W.M. van Soest; C.J. Freeman; A.S. Mobley; J. LaPietra; K. Cope; S. McKenna

    2010-01-01

    Background Saba Bank Atoll, Netherlands Antilles, is one of the three largest atolls on Earth and provides habitat for an extensive coral reef community. To improve our knowledge of this vast marine resource, a survey of biodiversity at Saba Bank included a multi-disciplinary team that sampled fishe

  3. Mosquitoes of the Netherlands Antilles and their hygienic importance

    NARCIS (Netherlands)

    Kuyp, van der Edwin

    1954-01-01

    The Netherlands Antilles may be divided into: (1) The Curaçao Group (or Netherlands Leeward Islands): Curaçao, Aruba and Bonaire. (2) The St. Martin Group (or Netherlands Windward Islands): (Netherlands) St. Maarten, Saba and St. Eustatius. The latter islands are very small, forming together only 8.

  4. Records of Syrphidae (Diptera) from the Lesser Antilles

    NARCIS (Netherlands)

    Doesburg, van P.H.

    1970-01-01

    Having terminated his term of office as a Director of the Suriname Museum at Paramaribo, Dr. D. C. GEIJSKES returned to Holland. Accompanied by Mrs. GEIJSKES he availed himself of the opportunity to make a collecting-trip to several islands of the Windward Group of the Lesser Antilles, situated in a

  5. The structure of rocky reef fish assemblages across a nearshore to coastal islands' gradient in Southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Fernando Zaniolo Gibran

    2012-01-01

    Full Text Available Local assemblages of fishes associated with reefs are influenced by interactions among the availability of larvae and survival of recruits with subsequent biotic and abiotic forcing, as well as by periodic and episodic disturbances of varying natures and magnitudes. Therefore, besides being structurally heterogeneous and patchily distributed, reef systems are strongly context-dependent due to the influence of a broad array of ecological processes. In order to assess interactions of local factors that influence the distribution and abundance of reef fishes within a coastal mosaic of rocky reefs, we tested the null hypothesis of no significant variation in fish assemblage structure, by comparing 33 sites along the northern coast of the São Paulo State, Southeastern Brazil. Replicated stationary visual census samples (n = 396 were obtained at different distances from the coast, depths and wave exposures, including the mainland, three relatively small coastal islands, and the two margins of a wide channel between the mainland and the large São Sebastião Island (~350 km², totaling 225 h of SCUBA diving. The regional rocky shore fish fauna comprised 106 species (41 families, with preponderance of diurnal mobile-invertebrate feeders. Samples from the outer margin of the São Sebastião Island, together with those from Alcatrazes, Búzios, and Vitória islands were significantly dissimilar from samples from the coastal sites at the São Sebastião Channel. Species richness tended to increase in a gradient from the coast to the more offshore islands. Local conditions such as depth and other habitat characteristics also influenced fish assemblages' structure. Distance from coast and depth were the main predictors for fish assemblages, followed by water transparency, temperature and benthic cover. This study represents the first regional-scale assessment of fish assemblages associated with rocky reefs in the São Paulo State coast, filling a major

  6. Changes in canopy structure and ant assemblages affect soil ecosystem variables as a foundation species declines:Ecosphere

    OpenAIRE

    Kendrick, Joseph A.; Ribbons, Relena Rose; Classen, Aimee Taylor; Ellison, Aaron M.

    2015-01-01

    The decline of Tsuga canadensis (eastern hemlock)?a foundation tree species?due to infestation by Adelges tsugae (hemlock woolly adelgid) or its complete removal from a stand by salvage logging dramatically affects associated faunal assemblages. Among these assemblages, species composition (richness and abundance) of ants increases rapidly as T. canadensis is lost from the stands. Because ants live and forage at the litter-soil interface, we hypothesized that environmental changes caused by h...

  7. Stable isotopes document the trophic structure of a deep-sea cephalopod assemblage including giant octopod and giant squid.

    Science.gov (United States)

    Cherel, Y; Ridoux, V; Spitz, J; Richard, P

    2009-06-23

    Although deep-sea cephalopods are key marine organims, their feeding ecology remains essentially unknown. Here, we report for the first time the trophic structure of an assemblage of these animals (19 species) by measuring the isotopic signature of wings of their lower beaks, which accumulated in stomachs of stranded sperm whales. Overall, the species encompassed a narrow range in delta(13)C values (1.7 per thousand), indicating that they lived in closely related and overlapping habitats. delta(13)C values can be interpreted in terms of distribution with the more (13)C-depleted species (e.g. Stigmatoteuthis arcturi, Vampyroteuthis infernalis) having a more pelagic habitat than the more (13)C-enriched, bathyal species (e.g. Todarodes sagittatus and the giant squid Architeuthis dux). The cephalopods sampled had delta(15)N values ranging 4.6 per thousand, which is consistent with the species spanning approximately 1.5 trophic levels. Neither the giant octopod (Haliphron atlanticus) nor the giant squid reached the highest trophic position. Species delta(15)N was independent of body size, with large squids having both the highest (Taningia danae) and lowest (Lepidoteuthis grimaldii) delta(15)N values. Their trophic position indicates that some species share the top of the food web, together with other megacarnivores such as the sperm whale. PMID:19324634

  8. Ecomorphological patterns of the fish assemblage in a tropical floodplain: effects of trophic, spatial and phylogenetic structures

    Directory of Open Access Journals (Sweden)

    Edson Fontes Oliveira

    2010-01-01

    Full Text Available Ecomorphological patterns of the fish assemblage from the upper Paraná River floodplain, Brazil, were described and evaluated according to trophic (guilds, spatial (habitats and phylogenetic (taxonomic distances structures. The samples were obtained through the Long Term Research Project (LTER-CNPq/UEM/NUPELIA in August and October 2001. Thirty-five species were analyzed from thirty-one morphological variables. Strong significant correlations (Mantel test between morphology and trophic guilds and between morphology and taxonomy were found, while morphology and habitat revealed a weak correlation. However, the partial Mantel test showed that the correlations between morphology and trophic guilds persist even when the effect of taxonomy is discounted. The ecomorphological pattern shown by the Principal Component Analysis separated species according to locomotion structures used in feeding. At one extreme there are the piscivores and insectivores that exploit lentic habitats and have compressed bodies and well developed anal fins, while at the other there are detritivores and invertivores that exploit lotic and semi-lotic habitats and have depressed bodies and well developed pectoral, pelvic and caudal fins. Canonical Discriminant Analysis using ecomorphological variables successfully predicted 94.5% of the trophic guild ecomorphotypes, but only 57.1% of the habitat ecomorphotypes. These data indicate that the fish assemblage of the upper Paraná River floodplain is structured ecomorphologically mainly according to trophic structure rather than habitat.Este trabalho objetivou descrever e avaliar os padrões ecomorfológicos da assembleia de peixes da planície de inundação do alto rio Paraná, Brasil, analisando os efeitos das estruturas trófica (guildas, espacial (tipos de habitats e filogenética (distância taxonômica. Trinta e cinco espécies foram analisadas a partir de 31 variáveis morfológicas obtidas de espécimes coletados em agosto

  9. A shift in the trophic structure of soil nematode assemblages in a Central European woodland - an indication of forest maturing or climate warming?

    Czech Academy of Sciences Publication Activity Database

    Háněl, Ladislav

    České Budějovice: Institute of Soil Biology, BC CAS, 2015. s. 21. ISBN ISBN 978-80-86525-29-7. [Central European Workshop on Soil Zoology /13./. 13.04.2015-15.04.2015, České Budějovice] R&D Projects: GA ČR(CZ) GA526/06/1348 Institutional support: RVO:60077344 Keywords : nematode assemblages * climate warming * trophic structure * Central European woodland Subject RIV: EH - Ecology, Behaviour

  10. The influence of fire on the assemblage structure of foraging birds in grasslands of the Serra da Canastra National Park, Brazil.

    Science.gov (United States)

    Reis, Matheus G; Fieker, Carolline Z; Dias, Manoel M

    2016-05-13

    Grasslands are the most threatened physiognomies of the Cerrado biome (Brazilian savanna), a biodiversity hotspot with conservation as a priority. The Serra da Canastra National Park protects the most important remnants of the Cerrado's southern grasslands, which are under strong anthropogenic pressure. The present study describes the structure of bird assemblages that directly use food resources in burned areas, comparing areas affected by natural fire to the areas where controlled fires were set (a management strategy to combat arson). The tested null hypothesis was that different bird assemblages are structured in a similar manner, regardless of the post-fire period or assessed area. Between December/2012 and January/2015, 92 species were recorded foraging in the study areas. The results indicate that both types of burnings triggered profound and immediate changes in bird assemblages, increasing the number of species and individuals. Natural fires exhibited a more significant influence on the structure (diversity and dominance) than prescribed burnings. Nevertheless, all the differences were no longer noticeable after a relatively short time interval of 2-3 months after prescribed burnings and 3-4 after natural fires. The findings may help the understanding of prescribed burnings as a management strategy for bird conservation in grasslands. PMID:27192195

  11. Effect of waterfalls and the flood pulse on the structure of fish assemblages of the middle Xingu River in the eastern Amazon basin.

    Science.gov (United States)

    Barbosa, T A P; Benone, N L; Begot, T O R; Gonçalves, A; Sousa, L; Giarrizzo, T; Juen, L; Montag, L F A

    2015-08-01

    The structure of fish assemblages in Neotropical rivers is influenced by a series of environmental, spatial and/or temporal factors, given that different species will occupy the habitats that present the most favourable conditions to their survival. The present study aims to identify the principal factors responsible for the structuring of the fish assemblages found in the middle Xingu River, examining the influence of environmental, spatial, and temporal factors, in addition to the presence of natural barriers (waterfalls). For this, data were collected every three months between July 2012 and April 2013, using gillnets of different sizes and meshes. In addition to biotic data, 17 environmental variables were measured. A total of 8,485 fish specimens were collected during the study, representing 188 species. Total dissolved solids, conductivity, total suspended matter, and dissolved oxygen concentrations were the variables that had the greatest influence on the characteristics of the fish fauna of the middle Xingu. Only the barriers and hydrological periods played a significant deterministic role, resulting in both longitudinal and lateral gradients. This emphasizes the role of the connectivity of the different habitats found within the study area in the structuring of its fish assemblages. PMID:26691079

  12. Land Change in the Greater Antilles between 2001 and 2010

    OpenAIRE

    Álvarez-Berríos, Nora L.; Daniel J. Redo; T. Mitchell Aide; Matthew L. Clark; Ricardo Grau

    2013-01-01

    Land change in the Greater Antilles differs markedly among countries because of varying socioeconomic histories and global influences. We assessed land change between 2001 and 2010 in municipalities (second administrative units) of Cuba, Dominican Republic, Haiti, Jamaica, and Puerto Rico. Our analysis used annual land-use/land-cover maps derived from MODIS satellite imagery to model linear change in woody vegetation, mixed-woody/plantations and agriculture/herbaceous vegetation. Using this a...

  13. Spatial and temporal structure of fish assemblages in a hyperhaline coastal system: Ría Lagartos, Mexico

    Directory of Open Access Journals (Sweden)

    Miguel Angel Peralta-Meixueiro

    2011-01-01

    Full Text Available The spatial and temporal fish species assemblages were analyzed throughout two annual cycles (2004-2005 and 2007-2008 in the Ría Lagartos Lagoon system, Mexico, via non-parametric multivariate analyses. We compared density and biomass of fish species among five habitat types defined by combinations of structure and environmental characteristics (hyperhaline, rocky, seagrass, channel, and marine, and three climatic seasons (dry, rainy, and northerlies. A total of 11,187 individuals distributed in 32 families and 63 species were collected. The most numerically abundant species were Floridichthys polyommus and Cyprinodon artifrons, while Sphoeroides testudineus contributed to the greatest biomass. Species composition consisted mainly of estuarine and euryhaline marine species. Spatially, a saline gradient was observed with marine conditions in the mouth, and increasing to over 100 in the inner zone of the system. Species richness, diversity and biomass declined from the mouth to the inner zone, while density showed an inverse tendency, with the highest values in the inner zone. Thus the salinity was the variable that best explained the spatial fish assemblages" structure. The ichthyofauna composition did not change over time, but the dominant species varied with the years. The abundance of juvenile specimens, suggest that the different habitats are used as feeding and breeding zones; hence it is proposed that protection strategies be pursued not only for the lagoon system but also for the northern zone of the Yucatan Peninsula.Los ensamblajes espacio temporales de peces fueron analizados a través de dos ciclos anuales (2004-2005 y 2007-2008 en el sistema lagunar Ría Lagartos, México, vía análisis multivariados no paramétricos. Se comparó la densidad y biomasa de peces entre los cinco tipos de hábitats definidos por la combinación de características estructurales y ambientales (hiperhalino, rocoso, pastos, canal y marino y tres temporadas

  14. The nematodes of the Thames estuary: Assemblage structure and biodiversity, with a test of Attrill's linear model

    Science.gov (United States)

    Ferrero, T. J.; Debenham, N. J.; Lambshead, P. J. D.

    2008-09-01

    Although many studies of Nematoda have been undertaken in estuarine systems, there are relatively few studies which have analysed the distribution of fauna across the entire salinity range from marine to freshwater conditions. The Thames estuary has a long history of anthropogenic impact and recovery, since it was described as "azoic" in the 1950s, which has been monitored primarily through studies of water quality and fish stocks, with less emphasis on macroinfauna and very little information on meiofaunal organisms. This study aimed to describe the nematode fauna at eight stations along the estuary from marine to freshwater conditions in order to assess patterns of density, diversity and species assemblage structure. Nematode density and diversity were generally lower in the middle reaches of the estuary, associated with the region of greatest salinity range, a pattern which was found to be in agreement with Attrill's [2002. A testable linear model for diversity trends in estuaries. Journal of Animal Ecology 71, 262-269] linear model. Multivariate analysis confirmed that each station supported a distinct nematode fauna, which could be used to identify five zones along the estuary related to salinity regime. Although alpha diversity at each station was relatively low, species turnover along the estuary resulted in relatively high gamma diversity (153 spp.) similar to that found in a number of European estuaries. The results of this study did not suggest that the nematode fauna was under significant stress from the lower levels of pollution currently found in the system. The potential routes for the recovery and re-colonization of the estuary since it most polluted days are discussed.

  15. Structural and functional responses of the oligochaete and aeolosomatid assemblage in lowland streams: a one-way-pollution-modelled ecosystem

    Directory of Open Access Journals (Sweden)

    Maria V. López van Oosterom

    2015-03-01

    Full Text Available We investigated the responses of the assemblage of Oligochaeta and Aeolosomatidae to organic pollution; comparing taxonomic richness, diversity, abundance, and diet of the individuals inhabiting two lowland streams with different degrees of anthropic impact (the Rodríguez and the Carnaval belonging to the Río de la Plata basin, Argentina. The physicochemical parameters in the Rodríguez Stream indicated a strong deterioration of the water quality compared to that of the Carnaval. A canonical-correlation analysis indicated that the Tubificinae, Megadrili, Enchytraeidae, and Rhyacodrilinae were more closely associated with the Rodríguez Stream; whereas the Naidinae, Pristininae, and Opystocystidae were more highly represented in the Carnaval. The diversity and taxonomic richness in the Rodríguez Stream exhibited significant differences from those of the Carnaval (P<0.001, but the abundance was not different between the two sites. Schoener’s index revealed the higher degree of dietary overlap of the two streams because all the species analysed consumed a high proportion of detritus, especially the organisms in the Rodríguez. In the Carnaval Stream a higher number of alimentary items were consumed, and mainly by the Naidinae. This difference, probably reflecting the greater availability of this resource at sites impacted by organic pollution, underscores the fundamental role of oligochaetes in the food webs of aquatic ecosystems. The combined use of structural and functional parameters enables a more comprehensive view of how these lotic systems function and as such provides information that will serve to design tools for the management of such temperate environments.

  16. Effects of a native and a non-native macrophyte species of Hydrocharitaceae on Chironomidae and Oligochaeta assemblages structure doi: 10.4025/actascibiolsci.v35i3.10855

    OpenAIRE

    Gisele Cristina Rosin; Alice Michiyo Takeda; Janielly Carvalho Camargo; Mariana Carolina Teixeira; Sue Ellen Prata Fernandes; Rômulo Diego de Lima Behrend

    2013-01-01

    This study investigated the structure of the Oligochaeta and Chironomidae assemblages associated with monospecific stands of two submerged macrophyte species: Egeria najas and Hydrilla verticillata. Samplings were carried out in Leopoldo Backwater and Paraná river, in August 2008. To assess the structure of Oligochaeta and Chironomidae assemblage in each macrophyte we calculated: species density, richness, diversity, and evenness. A detrended correspondence analysis (DCA) was used to summariz...

  17. Comments on systematics and zoogeography of bats in the Lesser Antilles

    NARCIS (Netherlands)

    Jones, J. Knox; Phillips, Carleton J.

    1970-01-01

    The Lesser Antilles, extending some 500 miles from Anguilla on the north to Grenada on the south, form an archipelago connecting the Greater Antilles with Trinidad and the South American mainland.¹) Bats comprise the major segment of the extant mammalian fauna of the Lesser Antillean islands and the

  18. 76 FR 38053 - Defense Federal Acquisition Regulation Supplement; Successor Entities to the Netherlands Antilles...

    Science.gov (United States)

    2011-06-29

    ... Regulation Supplement; Successor Entities to the Netherlands Antilles (DFARS Case 2011-D029) AGENCY: Defense... the change in the political status of the islands that comprised the Netherlands Antilles. DATES... became autonomous territories of the Kingdom of the Netherlands. Bonaire, Saba, and Sint Eustatius...

  19. Fish assemblages at engineered and natural channel structures in the lower Missouri river: implications for modified dike structures

    Science.gov (United States)

    Schloesser, J.T.; Paukert, Craig P.; Doyle, W.J.; Hill, T.; Steffensen, K.D.; Travnichek, Vincent H.

    2012-01-01

    Large rivers throughout the world have been modified by using dike structures to divert water flows to deepwater habitats to maintain navigation channels. These modifications have been implicated in the decline in habitat diversity and native fishes. However, dike structures have been modified in the Missouri River USA to increase habitat diversity to aid in the recovery of native fishes. We compared species occupancy and fish community composition at natural sandbars and at notched and un-notched rock dikes along the lower Missouri River to determine if notching dikes increases species diversity or occupancy of native fishes. Fish were collected using gill nets, trammel nets, otter trawls, and mini fyke nets throughout the lower 1212 river km of the Missouri River USA from 2003 to 2006. Few differences in species richness and diversity were evident among engineered dike structures and natural sandbars. Notching a dike structure had no effect on proportional abundance of fluvial dependents, fluvial specialists, and macrohabitat generalists. Occupancy at notched dikes increased for two species but did not differ for 17 other species (81%). Our results suggest that dike structures may provide suitable habitats for fluvial species compared with channel sand bars, but dike notching did not increase abundance or occupancy of most Missouri River fishes. Published in 2011 by John Wiley & Sons, Ltd.

  20. Hydrologic connectivity affects fish assemblage structure, diversity, and ecological traits in the unregulated Gambia River, West Africa

    Czech Academy of Sciences Publication Activity Database

    White, Seth M.; Ondračková, Markéta; Reichard, Martin

    2012-01-01

    Roč. 44, č. 4 (2012), s. 521-530. ISSN 0006-3606 R&D Projects: GA AV ČR IAA6093404 Institutional research plan: CEZ:AV0Z60930519 Institutional support: RVO:68081766 Keywords : fish assemblage * functional morphology * large tropical rivers * lateral migration * multivariate analysis * pre-impoundment * reference condition * trophic position Subject RIV: EH - Ecology, Behaviour Impact factor: 2.351, year: 2012

  1. Land Change in the Greater Antilles between 2001 and 2010

    Directory of Open Access Journals (Sweden)

    Nora L. Álvarez-Berríos

    2013-03-01

    Full Text Available Land change in the Greater Antilles differs markedly among countries because of varying socioeconomic histories and global influences. We assessed land change between 2001 and 2010 in municipalities (second administrative units of Cuba, Dominican Republic, Haiti, Jamaica, and Puerto Rico. Our analysis used annual land-use/land-cover maps derived from MODIS satellite imagery to model linear change in woody vegetation, mixed-woody/plantations and agriculture/herbaceous vegetation. Using this approach, we focused on municipalities with significant change (p ≤ 0.05. Between 2001 and 2010, the Greater Antilles gained 801 km2 of woody vegetation. This increase was mainly due to the return of woody vegetation in Cuba, and smaller increases in Puerto Rico and the Dominican Republic. Despite relatively similar environments, the factors associated with these changes varied greatly between countries. In Puerto Rico, Dominican Republic, and Jamaica, agriculture declined while mixed-woody vegetation increased, mostly in montane regions. In contrast, Cuba experienced an extensive decline in sugarcane plantations, which resulted in the spread of an invasive woody shrub species and the increase in woody vegetation in areas of high agricultural value. In Haiti, the growing population, fuelwood consumption, and increase in agriculture contributed to woody vegetation loss; however, woody vegetation loss was accompanied with a significant increase in the mixed woody and plantations class. Most regional analyses often treated the Greater Antilles as a homogeneous unit; our results suggest that historical and socio-economic differences among countries are crucial for understanding the variation in present day land change dynamics.

  2. Comics as Assemblage

    DEFF Research Database (Denmark)

    Cortsen, Rikke Platz

    the black panel and their spatio-temporal effects comparing various works by the same author or comics by man different artists. Building from this, a separate chapter analyses comics’ structure as a network with combining comics theory by Thierry Groensteen with Manuel DeLanda’s concept of assemblage......This thesis examines the apparent simplicity of comics by exposing some of the layers in which meaning is created in a complex network; it approaches the complexity of comics from the angle of spatio-temporality and separates comics into several spatio-temporal levels that each interacts in the way......-temporality of structure and in turn how this spatio-temporality is imagined through the spatio-temporality of the reader. Using Mikhail M. Bakhtin’s concept of the chronotope, I examine how the configuration of different spatio-temporalities interconnect in the superhero series Top 10. These spatio...

  3. Comparison of the seasonal variations of Synechococcus assemblage structures in estuarine waters and coastal waters of Hong Kong.

    Science.gov (United States)

    Xia, Xiaomin; Vidyarathna, Nayani K; Palenik, Brian; Lee, Puiyin; Liu, Hongbin

    2015-11-01

    Seasonal variation in the phylogenetic composition of Synechococcus assemblages in estuarine and coastal waters of Hong Kong was examined through pyrosequencing of the rpoC1 gene. Sixteen samples were collected in 2009 from two stations representing estuarine and ocean-influenced coastal waters, respectively. Synechococcus abundance in coastal waters gradually increased from 3.6 × 10(3) cells ml(-1) in March, reaching a peak value of 5.7 × 10(5) cells ml(-1) in July, and then gradually decreased to 9.3 × 10(3) cells ml(-1) in December. The changes in Synechococcus abundance in estuarine waters followed a pattern similar to that in coastal waters, whereas its composition shifted from being dominated by phycoerythrin-rich (PE-type) strains in winter to phycocyanin-only (PC-type) strains in summer owing to the increase in freshwater discharge from the Pearl River and higher water temperature. The high abundance of PC-type Synechococcus was composed of subcluster 5.2 marine Synechococcus, freshwater Synechococcus (F-PC), and Cyanobium. The Synechococcus assemblage in the coastal waters, on the other hand, was dominated by marine PE-type Synechococcus, with subcluster 5.1 clades II and VI as the major lineages from April to September, when the summer monsoon prevailed. Besides these two clades, clade III cooccurred with clade V at relatively high abundance in summer. During winter, the Synechococcus assemblage compositions at the two sites were similar and were dominated by subcluster 5.1 clades II and IX and an undescribed clade (represented by Synechococcus sp. strain miyav). Clade IX Synechococcus was a relatively ubiquitous PE-type Synechococcus found at both sites, and our study demonstrates that some strains of the clade have the ability to deal with large variation of salinity in subtropical estuarine environments. Our study suggests that changes in seawater temperature and salinity caused by the seasonal variation of monsoonal forcing are two major

  4. Changes in the structure and dynamics of marine assemblages dominated by Bifurcaria bifurcata and Cystoseira species over three decades (1977-2007)

    Science.gov (United States)

    Méndez-Sandín, Miguel; Fernández, Consolación

    2016-06-01

    Two low intertidal assemblages dominated in 1977 by Bifurcaria bifurcata and Cystoseira baccata-Saccorhiza polyschides in the North coast of Spain show changes in the structure and dynamics after 30 years. A re-survey in 2007 detected phenological changes affecting the annual cycle of dominant canopy species. B. bifurcata has shortened its growth period and undergone a decrease in biomass, while C. baccata lengthened its period of growth and increased its biomass. Also important were the disappearance of Saccorhiza polyschides and the increase of Cystoseira tamariscifolia. These changes affect the rest of the species of the assemblages, with a shift in the main understory species and an increase in crustose coralline algae although the overall biomass of the subcanopy was similar. The species richness shows a sharp increase, at the expense of increasing epiphytes and simpler functional and morphological groups. These biological changes agree with the general trends of increasing sea surface temperature and the relaxation of the summer upwelling affecting the North coast of Spain, but the results were unexpected in the case of Bifurcaria bifurcata.

  5. Diversity and structure of microcrustacean assemblages (Cladocera and Copepoda and limnological variability in perennial and intermittent pools in a semi-arid region, Bahia, Brazil

    Directory of Open Access Journals (Sweden)

    Nadson R. Simões

    2011-12-01

    Full Text Available Temporary wetlands undergo recurrent drought due to the scarcity of water, which disrupts the hydrological connectivity with adjacent aquatic systems. However, some environments retain water for longer periods, allowing greater persistence of the community. The current study evaluated differences in the microcrustacean assemblages and limnological variability between perennial and intermittent pools in a semi-arid region of Brazil. The abiotic features (water temperature, pH, total alkalinity, electrical conductivity and depth of intermittent pools were affected more than perennial pools due to loss of water volume. This may have contributed to a higher average richness and diversity index in some intermittent pools and differences in the structure of the assemblages. The lowest species richness and diversity were recorded where physical factors, such as a large quantity of suspended solids and variability in the electrical conductivity of the water and pH, make the environment unsuitable for these organisms. These results suggest that community development in intermittent pools is interrupted by the dry season; when the water returns, due to rainfall or rising groundwater, each pond undergoes a different process of colonization. In these circumstances, the biological importance of temporary aquatic environments is clear, since such pools provide shelters and have an important role in the maintenance of the regional diversity of aquatic environments.

  6. Structure and composition of the assemblage of parasitoids associated to Phyllocnistis citrella pupae Stainton (Lepidoptera: Gracillariidae) in citrus orchards in Southern Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Jahnke, Simone M.; Redaelli, Luiza R.; Soglio, Fabio K. Dal [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Dept. de Fitossanidade; Diefenbach, Lucia M.G. [Fundacao Estadual de Producao e Pesquisa em Saude (FEPPS), Porto Alegre, RS (Brazil). Inst. de Pesquisas Biologicas. Lab. Central do Estado (LACEN)

    2007-09-15

    The structure and composition of the assemblage of pupal parasitoids of Phyllocnistis citrella Stainton, the citrus leaf miner, were studied in two citrus orchards (Citrus deliciosa Tenore cv. Montenegrina and Citrus sinensis (L.) Osbeck x Citrus reticulata Blanco hybrid Murcott), in Montenegro County (29 deg 68S and 51 deg 46W), southern Brazil. At fortnightly samplings, from July 2001 to June 2003, all the new shoots from 24 randomly selected trees were inspected. The species richness reached five native species in the Murcott orchard, and six in Montenegrina. In Murcott, the presence of Ageniaspis citricola (Hymenoptera: Encyrtidae), an exotic species, was detected in the first year of sampling, probably migrating from the nearby areas where it had been released for the miner control. In Montenegrina, its presence was only registered in the second year. A. citricola in both areas was dominant and changed the community structure of parasitoid complex of P. citrella in both orchards. (author)

  7. Structure and composition of the assemblage of parasitoids associated to Phyllocnistis citrella Pupae Stainton (Lepidoptera: Gracillariidae) in citrus orchards in Southern Brazil.

    Science.gov (United States)

    Jahnke, Simone M; Redaelli, Luiza R; Diefenbach, Lúcia M G; Dal Soglio, Fábio K

    2007-01-01

    The structure and composition of the assemblage of pupal parasitoids of Phyllocnistis citrella Stainton, the citrus leafminer, were studied in two citrus orchards (Citrus deliciosa Tenore cv. Montenegrina and Citrus sinensis (L.) Osbeck x Citrus reticulata Blanco hybrid Murcott), in Montenegro County (29 degrees 68'S and 51 degrees 46'W), southern Brazil. At fortnightly samplings, from July 2001 to June 2003, all the new shoots from 24 randomly selected trees were inspected. The species richness reached five native species in the Murcott orchard, and six in Montenegrina. In Murcott, the presence of Ageniaspis citricola (Hymenoptera: Encyrtidae), an exotic species, was detected in the first year of sampling, probably migrating from the nearby areas where it had been released for the miner control. In Montenegrina, its presence was only registered in the second year. A. citricola in both areas was dominant and changed the community structure of parasitoid complex of P. citrella in both orchards. PMID:18060301

  8. Structure and composition of the assemblage of parasitoids associated to Phyllocnistis citrella pupae Stainton (Lepidoptera: Gracillariidae) in citrus orchards in Southern Brazil

    International Nuclear Information System (INIS)

    The structure and composition of the assemblage of pupal parasitoids of Phyllocnistis citrella Stainton, the citrus leaf miner, were studied in two citrus orchards (Citrus deliciosa Tenore cv. Montenegrina and Citrus sinensis (L.) Osbeck x Citrus reticulata Blanco hybrid Murcott), in Montenegro County (29 deg 68S and 51 deg 46W), southern Brazil. At fortnightly samplings, from July 2001 to June 2003, all the new shoots from 24 randomly selected trees were inspected. The species richness reached five native species in the Murcott orchard, and six in Montenegrina. In Murcott, the presence of Ageniaspis citricola (Hymenoptera: Encyrtidae), an exotic species, was detected in the first year of sampling, probably migrating from the nearby areas where it had been released for the miner control. In Montenegrina, its presence was only registered in the second year. A. citricola in both areas was dominant and changed the community structure of parasitoid complex of P. citrella in both orchards. (author)

  9. Stability and spatio-temporal structure in fish assemblages of two floodplain lagoons of the lower Orinoco River

    Directory of Open Access Journals (Sweden)

    Nirson González

    2009-01-01

    Full Text Available Fish assemblage structure and variability were analyzed in two floodplain lagoons (Las Arhuacas and Los Cardonales along the lower Orinoco over a hydrological cycle. Every three months during continuous three-day sampling, experimental gill nets (5 to 12.5 cm of mesh opening and 1 mm-mesh seine nets were utilized according to the types of habitats presents. A total of 133 fish species were found in Las Arhuacas and 95 species in Cardonales. Fifty five and 17 species were exclusive to Las Arhuacas and Los Cardonales respectively, and 77 were common to both lagoons. In Las Arhuacas, the most speciesrich orders were Characiformes, Siluriformes, Perciformes and Gymnotiformes and in Los Cardonales, the most species-rich orders were Characiformes, Siluriformes, Clupeiformes and Perciformes. The richness, abundance and biomass were significantly higher (p Foram analisadas a estrutura e a variabilidade da comunidade de peixes ao longo de um ciclo hidrológico em dois lagos (Arhuacas e Cardonales da planície de inundação do baixo rio Orinoco. Amostragens trimestrais foram realizadas por meio de coletas contínuas durante três dias, utilizando-se redes de espera experimentais (5 a 12,5 cm de malha e redes de arrasto (1 mm de malha, de acordo com os tipos de habitats presentes. Foi encontrado um total de 133 espécies de peixes em Arhuacas e 95 espécies em Cardonales. Cinquenta e cinco espécies foram exclusivas do lago Arhuacas, 17 do lago Cardonales, e 77 foram comuns a ambos os lagos. Em Arhuacas, as ordens mais ricas em espécies foram Characiformes, Siluriformes, Perciformes e Gymnotiformes; em Cardonales, foram Characiformes, Siluriformes, Clupeiformes e Perciformes. A riqueza, abundância e biomassa foram significativamente mais altas (p < 0.001 em Arhuacas que em Cardonales. A comunidade de peixes teve alta variação durante a fase de cheia e permanceu moderadamente estável durante fase de seca em ambos os lagos, com mais estabilidade ou

  10. Application of “taxocene surrogation” and “taxonomic sufficiency” concepts to fish farming environmental monitoring. Comparison of BOPA index versus polychaete assemblage structure

    OpenAIRE

    Aguado Giménez, Felipe; Gairin Deulofeu, Joan Ignasi; Martinez-Garcia, Elena; Fernandez-Gonzalez, Victoria; Ballester-Moltó, Mateo; Cerezo-Valverde, Jesús; Sanchez-Jerez, Pablo

    2015-01-01

    “Taxocene surrogation” and “taxonomic sufficiency” concepts were applied to the monitoring of soft bottoms macrobenthic assemblages influenced by fish farming following two approaches. Polychaete assemblage evaluation through multivariate analysis and the benthic index BOPA were compared. Six fish farms along the Spanish Mediterranean coast were monitored. Polychaete assemblage provided a suitable picture of the impact gradient, being correlated with total free sulphides. BOPA did not support...

  11. How wide is the seismogenic zone of the Lesser Antilles forearc?

    Science.gov (United States)

    Gutscher, M.; Westbrook, G. K.; Marcaillou, B.; Graindorge, D.; Gailler, A.; Pichot, T.; Maury, R.

    2009-12-01

    The Lesser Antilles subduction zone has produced no recent strong thrust earthquakes, making it difficult to quantify the seismic hazard from such events. Numerical models of forearc thermal structure were constructed along six transects perpendicular to the arc in order to determine the thermally predicted width of the seismogenic zone. The geometry of each section is constrained by published seismic profiles and by earthquake hypocenters at depth. The dip of the deep slab ranges from 53° in the north to 45° in the south. The age of the subducting oceanic lithosphere is 80 Ma and the subduction velocity 2 cm/yr. The temperature beneath the volcanic arc (1100-1200°C) as well as observed surface heat flow provide some constraints on the modeled thermal structure. Modeling results indicate a systematic southward increase in the width of the seismogenic zone, more than doubling in width from north to south and corresponding to a dramatic southward increase in forearc width (trench - arc distance). The minimum width (as defined by the 150°C and 350°C isotherms) increases from about 80 km north of 16°N to 230 km at 13°N, respectively. The maximum width (as defined by the 100°C and 450°C isotherms) ranges from 150-160 km in the north to up to 320 km in the south. There is good agreement between the thermally predicted seismogenic limits and the sparse distribution of recorded thrust earthquakes, which are observed only in the northern portion of the arc. Possible scenarios for mega-thrust earthquakes are discussed. Depending on the segment length (along-strike) of the rupture plane, an event of magnitude 8-9 cannot be excluded. (left) seismicity map of the Lesser Antilles with focal mechanisms of shallow dipping thrust type earthquakes shown and the possible rupture zones of the 1839 and 1844 earthquakes (intensities X) the position of the cross section at right is indicated; (right) modeled thermal structure for a transect through Guadeloupe, with earthquake

  12. Coastal stratigraphies of eastern Bonaire (Netherlands Antilles): New insights into the palaeo-tsunami history of the southern Caribbean

    Science.gov (United States)

    Engel, Max; Brückner, Helmut; Wennrich, Volker; Scheffers, Anja; Kelletat, Dieter; Vött, Andreas; Schäbitz, Frank; Daut, Gerhard; Willershäuser, Timo; May, Simon Matthias

    2010-11-01

    A sediment record of three alluvial sites along the east- and northeast-oriented shore of Bonaire (Netherlands Antilles) provides evidence for the recurrence of several extraordinary wave impacts during the Holocene. The interpretation of onshore high-energy wave deposits is controversially discussed in recent sedimentary research. However, it represents a powerful tool to evaluate the hazard of tsunami and severe storms where historical documentation is short and/or fragmentary. A facies model was established based on sedimentary and geochemical characteristics as well as the assemblage and state of preservation of shells and shell fragments. Radiocarbon data and the comparison of the facies model with both recent local hurricane deposits and global "tsunami signature types" point to the occurrence of three major wave events around 3300, 2000-1700 and shortly before 500 BP. Since (i) the stratigraphically correlated sand layers fulfill several sedimentary characteristics commonly associated with tsunamis and (ii) modern strong hurricanes left only little or even no sediment in the study areas, they were interpreted as tsunamigenic. However, surges largely exceeding the energy of those accompanying modern hurricanes in the southern Caribbean cannot entirely be ruled out. The results are partially consistent with existing chronologies for Holocene extreme wave events deduced from supralittoral coarse-clast deposits on Aruba, Bonaire and Curaçao as well as overwash sediments from Cayo Sal, Venezuela.

  13. Deep-water stands of Cystoseira zosteroides C. Agardh (Fucales, Ochrophyta) in the Northwestern Mediterranean: Insights into assemblage structure and population dynamics

    Science.gov (United States)

    Ballesteros, Enric; Garrabou, Joaquim; Hereu, Bernat; Zabala, Mikel; Cebrian, Emma; Sala, Enric

    2009-04-01

    Populations dominated by Cystoseira zosteroides, an endemic and threatened Mediterranean seaweed, colonize deep-water rocky habitats down to more than 50 m depth. Assemblages dominated by this species display high algal and invertebrate species richness. Algal biomass averages 1134 g dw m -2. Erect and turf algae account for only 25% of total algal dry weight, while encrusting corallines are responsible for the remaining 75%. Sponges, bryozoans and ascidians constitute the dominant sessile macrofauna. Cystoseira zosteroides is the dominant erect algae, with a mean biomass of 60.6 g dw m -2, and densities ranging from 4 to 7 plants m -2. The alien turf alga Womersleyella setacea has a biomass of 104.2 g dw m -2 and covers most of the understory substrate. The size-frequency distribution of C. zosteroides populations shows differences over time. Mean annual growth of the main axis is around 0.5 cm and mean annual mortality rate is lower than 2%. Recruitment was almost nil during the studied period of time (10 years). Processes structuring these deep-water Cystoseira stands must be driven by episodic disturbances, after-disturbance recruitment pulses, and long periods of steady growth that last at least 10 years. However, it is also possible that recruitment is irreversibly inhibited by the alien alga W. setacea in which case these old-growth stands are faced with extinction. The highly diversified assemblages and the low growth and low mortality rates of C. zosteroides indicate high vulnerability to natural and anthropogenic disturbances, and call for effective measures to ensure their conservation.

  14. Seasonal variability of morphospaces in a subtropical fish assemblage

    OpenAIRE

    Carolina Correia Siliprandi; Antoni Lombarte

    2015-01-01

    Morphological characters of fishes are essential to evaluate the functional structure of assemblages, being morphological differences indicative of distinct ecological and adaptive strategies. The ecomorphology using morphospaces analyzes the structure of a fish assemblage through the values of intervals between homologous points positioned in anatomical structures of organisms phylogenetically related. These intervals can be quantified by morphogeometric and multivariate analyses. Seasonally...

  15. A community-level, mesoscale analysis of fish assemblage structure in shoreline habitats of a large river using multivariate regression trees

    Science.gov (United States)

    Wilkes, Martin; Maddock, Ian; Link, Oscar; Habit, Evelyn

    2015-04-01

    Despite the numerous advantages over traditional methods ascribed to community-level analyses, including the ability to rapidly predict the abundance of multiple species and the integration of complex biological interactions, very few applications to the mesoscale of river habitats can be found in the extant literature. Most previous work has been based on single species, species-by-species modelling or reduced dimensionality approaches. Community-level analyses have especially good properties for improving the understanding of habitat associations in large rivers where biological interactions are most intense and applications of the mesohabitat concept relatively sparse. This chapter seeks to identify quantitative relationships between key environmental variables and community structure using a particular type of community-level technique known as multivariate regression trees in order to test the ecological basis for applications of the mesohabitat concept in large rivers. Mesohabitats were mapped and their environmental characteristics recorded along a reach of the San Pedro River, Chile, which is inhabited by a highly endemic fish community. A representative portion of the mesohabitats were selected for fish sampling and multivariate regression trees produced to predict community structure based on combinations of environmental variables. The analyses showed that fish assemblages were distinct at the mesoscale, with flow depth, bank materials, cover and woody debris the key predictor variables. The results support the application of the mesohabitat concept in this geographical context and establish a basis for predicting the community structure of any mesohabitat along the reach.

  16. The response of spider (Araneae assemblages to structural heterogeneity and prey abundance in sub-montane vegetation modified by conservation grazing

    Directory of Open Access Journals (Sweden)

    Peter Dennis

    2015-01-01

    Full Text Available The effect of experimental livestock grazing regimens (4 treatments×6 replicates on spiders via habitat structure and prey abundance was investigated on sub-montane habitats in the Southern Highlands of Scotland. The study, 2002–2004 included a baseline survey under the prior, commercial sheep grazing regimen and two assessments of spider assemblages post-treatment: commercial stocking density of sheep; 1/3 stocking density with sheep; 1/3 stocking density cattle with sheep; and no grazing. Spiders were sampled with a suction sampler, five sucks at each of 25 sample units by 24 plots (600 samples in 2003 and 2004, ca. 320 in 2002. Spider abundance and species richness increased under reduced stocking density, mixed herbivore and ungrazed treatments indirectly via changes in vegetation structure and prey abundance. The results refuted a meta-analysis that concluded species richness of spiders is unaffected by grazing. Grazing regimens caused turnover in species composition more than the net difference in species richness suggested, implying that no single, optimal grazing regimen will support as many species as a patchwork under varied grazing management. Conservation grazing benefits spiders and will have significant benefits for food webs in sub-montane ecosystems but the period to equilibrium after changes to grazing requires further investigation.

  17. Preliminary Assessment of Sponge Biodiversity on Saba Bank, Netherlands Antilles

    Science.gov (United States)

    Thacker, Robert W.; Díaz, M. Cristina; de Voogd, Nicole J.; van Soest, Rob W. M.; Freeman, Christopher J.; Mobley, Andrew S.; LaPietra, Jessica; Cope, Kevin; McKenna, Sheila

    2010-01-01

    Background Saba Bank Atoll, Netherlands Antilles, is one of the three largest atolls on Earth and provides habitat for an extensive coral reef community. To improve our knowledge of this vast marine resource, a survey of biodiversity at Saba Bank included a multi-disciplinary team that sampled fishes, mollusks, crustaceans, macroalgae, and sponges. Methodology/Principal Findings A single member of the dive team conducted surveys of sponge biodiversity during eight dives at six locations, at depths ranging from 15 to 30 m. This preliminary assessment documented the presence of 45 species pooled across multiple locations. Rarefaction analysis estimated that only 48 to 84% of species diversity was sampled by this limited effort, clearly indicating a need for additional surveys. An analysis of historical collections from Saba and Saba Bank revealed an additional 36 species, yielding a total of 81 sponge species recorded from this area. Conclusions/Significance This observed species composition is similar to that found on widespread Caribbean reefs, indicating that the sponge fauna of Saba Bank is broadly representative of the Caribbean as a whole. A robust population of the giant barrel sponge, Xestospongia muta, appeared healthy with none of the signs of disease or bleaching reported from other Caribbean reefs; however, more recent reports of anchor chain damage to these sponges suggests that human activities can have dramatic impacts on these communities. Opportunities to protect this extremely large habitat should be pursued, as Saba Bank may serve as a significant reservoir of sponge species diversity. PMID:20502643

  18. Preliminary assessment of sponge biodiversity on Saba Bank, Netherlands Antilles.

    Directory of Open Access Journals (Sweden)

    Robert W Thacker

    Full Text Available BACKGROUND: Saba Bank Atoll, Netherlands Antilles, is one of the three largest atolls on Earth and provides habitat for an extensive coral reef community. To improve our knowledge of this vast marine resource, a survey of biodiversity at Saba Bank included a multi-disciplinary team that sampled fishes, mollusks, crustaceans, macroalgae, and sponges. METHODOLOGY/PRINCIPAL FINDINGS: A single member of the dive team conducted surveys of sponge biodiversity during eight dives at six locations, at depths ranging from 15 to 30 m. This preliminary assessment documented the presence of 45 species pooled across multiple locations. Rarefaction analysis estimated that only 48 to 84% of species diversity was sampled by this limited effort, clearly indicating a need for additional surveys. An analysis of historical collections from Saba and Saba Bank revealed an additional 36 species, yielding a total of 81 sponge species recorded from this area. CONCLUSIONS/SIGNIFICANCE: This observed species composition is similar to that found on widespread Caribbean reefs, indicating that the sponge fauna of Saba Bank is broadly representative of the Caribbean as a whole. A robust population of the giant barrel sponge, Xestospongia muta, appeared healthy with none of the signs of disease or bleaching reported from other Caribbean reefs; however, more recent reports of anchor chain damage to these sponges suggests that human activities can have dramatic impacts on these communities. Opportunities to protect this extremely large habitat should be pursued, as Saba Bank may serve as a significant reservoir of sponge species diversity.

  19. Trophic organization and fish assemblage structure as disturbance indicators in headwater streams of lower Sorocaba River basin, Sao Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Bruna Botti Cruz

    2013-03-01

    Full Text Available Studies that investigate the relationship patterns between environmental structure complexity and fish fauna provide crucial information to stream restoration efforts. In order to test the hypothesis that streams with more complex environmental structure sustain more diverse and functionally more complex fish communities we sampled fish fauna from Sorocaba River headwater stream reaches (SE - Brazil. Reaches represented two distinct treatments: (1 a simplified reach, characterized by unstable fine substrate, clay, deeper channel and higher water velocity and (2 structurally complex reaches, characterized by coarse substrate, with gravel, pebble, rock, stems and branches and leaves inside the channel, producing a diverse pattern of microhabitat, associated with sequences of pools, runs, and riffles. Both trophic structure and taxonomic composition varied significantly between treatments. Invertivorous trophic group exclusively occurred in structurally complex reaches, which also presented greater diversity and species richness. We suggest enhancing in-stream environmental structure that suffered simplification processes due to human impacts in order to reestablish fish communities and ecossistemic functioning.

  20. Spatial variation of dung beetle assemblages associated with forest structure in remnants of southern Brazilian Atlantic Forest

    Directory of Open Access Journals (Sweden)

    Pedro Giovâni da Silva

    2016-03-01

    Full Text Available ABSTRACT The Brazilian Atlantic Forest is one of the world's biodiversity hotspots, and is currently highly fragmented and disturbed due to human activities. Variation in environmental conditions in the Atlantic Forest can influence the distribution of species, which may show associations with some environmental features. Dung beetles (Coleoptera: Scarabaeinae are insects that act in nutrient cycling via organic matter decomposition and have been used for monitoring environmental changes. The aim of this study is to identify associations between the spatial distribution of dung beetle species and Atlantic Forest structure. The spatial distribution of some dung beetle species was associated with structural forest features. The number of species among the sampling sites ranged widely, and few species were found in all remnant areas. Principal coordinates analysis indicated that species composition, abundance and biomass showed a spatially structured distribution, and these results were corroborated by permutational multivariate analysis of variance. The indicator value index and redundancy analysis showed an association of several dung beetle species with some explanatory environmental variables related to Atlantic Forest structure. This work demonstrated the existence of a spatially structured distribution of dung beetles, with significant associations between several species and forest structure in Atlantic Forest remnants from Southern Brazil.

  1. Affects and assemblages

    DEFF Research Database (Denmark)

    Samson, Kristine

    happens to aesthetics and how does it change the existing social and geographical understanding of urban space? The paper sets out to reintroduce aesthetical aspects of affects and assemblages in relation to urban space and urban planning. It presupposes urban space as a continuous state of becoming where...... ‘throwntogetherness’ (Massey 2005) or assemblage (Farias & Bender 2010) of perspectives bridging for instance the social and cultural experienced space investigated by the geographer and urban sociologist with the material and formal aesthetics of the architect and urban planner....... cultural geopgraphy. On this backdrop the paper states that affects and assemblages could serve as key notions for the reassembling the aesthetics of urban space. Thus, the paper suggest a less formal understanding of urban space and aesthetics, proposing an understanding of aesthetics as a...

  2. Boron isotope ratios of surface waters in Guadeloupe, Lesser Antilles

    Energy Technology Data Exchange (ETDEWEB)

    Louvat, Pascale, E-mail: louvat@ipgp.fr [Geochimie et Cosmochimie, IPGP, Universite Paris Diderot, Sorbonne Paris Cite, UMR 7154 CNRS, 75005 Paris (France); Gaillardet, Jerome; Paris, Guillaume; Dessert, Celine [Geochimie et Cosmochimie, IPGP, Universite Paris Diderot, Sorbonne Paris Cite, UMR 7154 CNRS, 75005 Paris (France)

    2011-06-15

    Highlights: > Rivers outer of hydrothermal areas have d11B around 40 per mille and [B] of 10-31 {mu}g/L. > Thermal springs have d11B of 8-15 per mille and [B] between 250 and 1000 {mu}g/L. > With Na, SO{sub 4} and Cl, boron shows mixing of rain, low and high-T weathering inputs. > Guadeloupe rivers and thermal springs have d11B 20-40 per mille higher than the local rocks. > Solid-solution fractionation during weathering pathways may explain this gap of d11B. - Abstract: Large variations are reported in the B concentrations and isotopic ratios of river and thermal spring waters in Guadeloupe, Lesser Antilles. Rivers have {delta}{sup 11}B values around 40 per mille and B concentrations lower than 30 {mu}g/L, while thermal springs have {delta}{sup 11}B of 8-15 per mille and B concentrations of 250-1000 {mu}g/L. River samples strongly impacted by hydrothermal inputs have intermediate {delta}{sup 11}B and B contents. None of these surface water samples have {delta}{sup 11}B comparable to the local unweathered volcanic rocks (around 0 per mille), implying that a huge isotopic fractionation of 40 per mille takes place during rock weathering, which could be explained by preferential incorporation of {sup 10}B during secondary mineral formation and adsorption on clays, during rock weathering or in the soils. The soil-vegetation B cycle could also be a cause for such a fractionation. Atmospheric B with {delta}{sup 11}B of 45 per mille represents 25-95% of the river B content. The variety of the thermal spring chemical composition renders the understanding of B behavior in Guadeloupe hydrothermal system quite difficult. Complementary geochemical tracers would be helpful.

  3. Seasonal patterns of activity and community structure in an amphibian assemblage at a pond network with variable hydrology

    Science.gov (United States)

    Vignoli, Leonardo; Bologna, Marco A.; Luiselli, Luca

    2007-03-01

    We studied community structure and seasonal activity patterns in a system of four ponds with seasonally-variable hydrology at a Mediterranean area in central Italy. We used a set of field methods to assess species presence and relative frequency of observation. The network of ponds was inhabited by six species of amphibians, two salamanders and four frogs. The breeding phenology of the six species did not vary remarkably among ponds, but there were significant differences among species in use of ponds. Factorial analysis of pond similarity drawn from percentage composition of the amphibian fauna, revealed that each of the four ponds was treatable as independent units, with no influence of relative inter-pond distance. PCA analysis allowed us to spatially arrange the amphibian species into three main groups: two were monospecific groups (i.e., Triturus vulgaris and Bufo bufo) and the third consisted of those species that selected not only the largest-deepest ponds, but also the ephemeral ones (i.e., Triturus carnifex, Hyla intermedia, the green frogs and Rana dalmatina). Our results suggest that the inter-pond differences in riparian vegetation, water depth, aquatic vegetation structure/abundance, and soil composition may produce differences among pond ecological characteristics (i.e., water turbidity and temperature, shelter availability, abundance of oviposition micro-sites), which may in turn influence different patterns of use by amphibians. To our knowledge, this is the first study emphasizing the potential role of heterochrony in the maintenance of a high species richness in Mediterranean amphibian communities. Preservation of freshwater vertebrate biodiversity requires management and protection not only of the main ponds and water bodies but also the temporary and ephemeral shallow ponds.

  4. Community structure across a large-scale ocean productivity gradient: Marine bird assemblages of the Southern Indian Ocean

    Science.gov (United States)

    Hyrenbach, K. David; Veit, Richard R.; Weimerskirch, Henri; Metzl, Nicolas; Hunt, George L., Jr.

    2007-07-01

    Our objective was to understand how marine birds respond to oceanographic variability across the Southern Indian Ocean using data collected during an 16-day cruise (4-21 January 2003). We quantified concurrent water mass distributions, ocean productivity patterns, and seabird distributions across a heterogeneous pelagic ecosystem from subtropical to sub-Antarctic waters. We surveyed 5155 km and sighted 15,606 birds from 51 species, and used these data to investigate how seabirds respond to spatial variability in the structure and productivity of the ocean. We addressed two spatial scales: the structure of seabird communities across macro-mega scale (1000 s km) biogeographic domains, and their coarse-scale (10 s km) aggregation at hydrographic and bathymetric gradients. Both seabird density and species composition changed with latitudinal and onshore-offshore gradients in depth, water temperature, and chlorophyll-a concentration. The average seabird density increased across the subtropical convergence (STC) from 2.4 birds km -2 in subtropical waters to 23.8 birds km -2 in sub-Antarctic waters. The composition of the avifauna also differed across biogeographic domains. Prions ( Pachyptila spp.) accounted for 57% of all sub-Antarctic birds, wedge-tailed shearwaters ( Puffinus pacificus) accounted for 46% of all subtropical birds, and Indian Ocean yellow-nosed albatross ( Thallasarche carteri) accounted for 32% of all birds in the STC. While surface feeders were the most abundant foraging guild across the study area, divers were disproportionately more numerous in the sub-Antarctic domain, and plungers were disproportionately more abundant in subtropical waters. Seabird densities were also higher within shallow shelf-slope regions, especially in sub-Antarctic waters, where large numbers of breeding seabirds concentrated. However, we did not find elevated seabird densities along the STC, suggesting that this broad frontal region is not a site of enhanced aggregation.

  5. Fashion, Mediations & Method Assemblages

    DEFF Research Database (Denmark)

    Sommerlund, Julie; Jespersen, Astrid Pernille

    , it is an important ambition of this paper to go into a methodological discussion of how "that which effectively happens" can be approached. To this end, the paper will combine Hennion's term of the "mediator" with John Laws methodological term of "method assemblages". Method assemblages is a suggested as a way...... relations between individuals and social contexts, aesthetics and production, distribution and consumption, as well as relations between fluidity and stability. By addressing the field of fashion, the paper proposes to shed light on an empirical setting which has so far been studied either as a purely...... - Domestication of the Scallops and Fishermen of St. Brieuc Bay. Power, Action, and Belief - A New Sociology of Knowledge. J. Law. London, Routledge and Keagan Paul: 196-233. Hennion, A. (1997). "Baroque and rock: Music, mediators and musical taste." Poetics 24: 414 - 435. Latour, B. (1993). We Have Never Been...

  6. Spatial and temporal changes in invertebrate assemblage structure from the entrance to deep-cave zone of a temperate marble cave

    Directory of Open Access Journals (Sweden)

    Benjamin W. Tobin

    2013-09-01

    Full Text Available Seasonality in surface weather results in seasonal temperature and humidity changes in caves. Ecological and physiological differences among trogloxenes, troglophiles, and troglobionts result in species-dependent responses to this variability. To investigate these responses, we conducted five biological inventories in a marble cave in the Sierra Nevada Range, California, USA between May and December 2010. The cave was divided into six quadrats and temperature was continuously logged in each (humidity was logged at the entrance and in the deep cave. With increasing distance from the entrance, temperature changes were increasingly attenuated and lagged relative to surface temperature. Linear regressions were created to determine the relationship between measured environmental variables and diversity for cavernicoles (troglobionts and troglophiles and trogloxenes cave– wide and in the transition zone. Diversity for cavernicoles and trogloxenes peaked in the entrance and deep cave zones, respectively. Quadrat, date, 2-week antecedent temperature average, 2-week antecedent temperature range, and trogloxene abundance explained 76% of cavernicole diversity variability. Quadrat explained 55% of trogloxene diversity variability. In the transition zone, trogloxene abundance explained 26% of cavernicole variability and 2-week antecedent temperature and 2-week antecedent temperature range explained 40% of trogloxene variability. In the transition zone, trogloxene diversity was inversely related to 2-week antecedent temperature average and 2-week antecedent temperature range, suggesting that species were moving into the transition zone when temperature was most stable. In a CCA of cavernicoles distribution data and environmental variables, 35% of variation in species-specific distributions was attributable to quadrat, and non-significant percentages were explained by date and environmental variables. Differences in assemblage structure among quadrats were

  7. Biological Assessment of Aquaculture Effects on Effluent-Receiving Streams in Ghana Using Structural and Functional Composition of Fish and Macroinvertebrate Assemblages

    Science.gov (United States)

    Ansah, Yaw Boamah; Frimpong, Emmanuel A.; Amisah, Stephen

    2012-07-01

    Biological assessment of aquatic ecosystems is widely employed as an alternative or complement to chemical and toxicity testing due to numerous advantages of using biota to determine ecosystem condition. These advantages, especially to developing countries, include the relatively low cost and technical requirements. This study was conducted to determine the biological impacts of aquaculture operations on effluent-receiving streams in the Ashanti Region of Ghana. We collected water, fish and benthic macroinvertebrate samples from 12 aquaculture effluent-receiving streams upstream and downstream of fish farms and 12 reference streams between May and August of 2009, and then calculated structural and functional metrics for biotic assemblages. Fish species with non-guarding mode of reproduction were more abundant in reference streams than downstream ( P = 0.0214) and upstream ( P = 0.0251), and sand-detritus spawning fish were less predominant in reference stream than upstream ( P = 0.0222) and marginally less in downstream locations ( P = 0.0539). A possible subsidy-stress response of macroinvertebrate family richness and abundance was also observed, with nutrient (nitrogen) augmentation from aquaculture and other farming activities likely. Generally, there were no, or only marginal differences among locations downstream and upstream of fish farms and in reference streams in terms of several other biotic metrics considered. Therefore, the scale of impact in the future will depend not only on the management of nutrient augmentation from pond effluents, but also on the consideration of nutrient discharges from other industries like fruit and vegetable farming within the study area.

  8. Thermochronology and tectonics of the Leeward Antilles: Evolution of the southern Caribbean Plate boundary zone

    Science.gov (United States)

    van der Lelij, Roelant; Spikings, Richard A.; Kerr, Andrew C.; Kounov, Alexandre; Cosca, Michael; Chew, David; Villagomez, Diego

    2010-01-01

    Tectonic reconstructions of the Caribbean Plate are severely hampered by a paucity of geochronologic and exhumation constraints from anastomosed basement blocks along its southern margin. New U/Pb, 40Ar/39Ar, apatite fission track, and apatite (U-Th)/He data constrain quantitative thermal and exhumation histories, which have been used to propose a model for the tectonic evolution of the emergent parts of the Bonaire Block and the southern Caribbean Plate boundary zone. An east facing arc system intruded through an oceanic plateau during ~90 to ~87 Ma and crops out on Aruba. Subsequent structural displacements resulted in >80°C of cooling on Aruba during 70–60 Ma. In contrast, exhumation of the island arc sequence exposed on Bonaire occurred at 85–80 Ma and 55–45 Ma. Santonian exhumation on Bonaire occurred immediately subsequent to burial metamorphism and may have been driven by the collision of a west facing island arc with the Caribbean Plate. Island arc rocks intruded oceanic plateau rocks on Gran Roque at ~65 Ma and exhumed rapidly at 55–45 Ma. We attribute Maastrichtian-Danian exhumation on Aruba and early Eocene exhumation on Bonaire and Gran Roque to sequential diachronous accretion of their basement units to the South American Plate. Widespread unconformities indicate late Eocene subaerial exposure. Late Oligocene–early Miocene dextral transtension within the Bonaire Block drove subsidence and burial of crystalline basement rocks of the Leeward Antilles to ≤1 km. Late Miocene–recent transpression caused inversion and ≤1 km of exhumation, possibly as a result of the northward escape of the Maracaibo Block.

  9. Oblique Collision of the Leeward Antilles, Offshore Venezuela: Linking Onshore and Offshore Data from BOLIVAR

    Science.gov (United States)

    Beardsley, A. G.; Avé Lallemant, H. G.; Levander, A.; Clark, S. A.

    2006-12-01

    The kinematic history of the Leeward Antilles (offshore Venezuela) can be characterized with the integration of onshore outcrop data and offshore seismic reflection data. Deformation structures and seismic interpretation show that oblique convergence and wrench tectonics have controlled the diachronous deformation identified along the Caribbean - South America plate boundary. Field studies of structural features in outcrop indicate one generation of ductile deformation (D1) structures and three generations of brittle deformation (F1 - F3) structures. The earliest deformation (D1/F1) began ~ 110 Ma with oblique convergence between the Caribbean plate and South American plate. The second generation of deformation (F2) structures initiated in the Eocene with the extensive development of strike-slip fault systems along the diffuse plate boundary and the onset of wrench tectonics within a large-scale releasing bend. The most recent deformation (F3) has been observed in the west since the Miocene where continued dextral strike-slip motion has led to the development of a major restraining bend between the Caribbean plate transform fault and the Oca - San Sebastian - El Pilar fault system. Deformation since the late Cretaceous has been accompanied by a total of 135° clockwise rotation. Interpretation of 2D marine reflection data indicates similar onshore and offshore deformation trends. Seismic lines that approximately parallel the coastline (NW-SE striking) show syndepositional normal faulting during F1/F2 and thrust faulting associated with F3. On seismic lines striking NNE-SSW, we interpret inversion of F2 normal faults with recent F3 deformation. We also observe both normal and thrust faults related to F3. The thick sequence of recent basin sedimentation (Miocene - Recent), interpreted from the seismic data, supports the ongoing uplift and erosion of the islands; as suggested by fluid inclusion analysis. Overall, there appears to be a strong correlation between

  10. Meiofaunal assemblages associated with native and non-indigenous macroalgae

    Science.gov (United States)

    Veiga, Puri; Sousa-Pinto, Isabel; Rubal, Marcos

    2016-07-01

    Meiofauna is a useful tool to detect effects of different disturbances; however, its relevance in the frame of biological invasions has been almost fully neglected. Meiofaunal assemblages associated with the invasive macroalga Sargassum muticum were studied and compared with those associated with two native macroalgae (Bifurcaria bifurcata and Chondrus crispus). We used a linear mixed model to determine the influence of habitat size (i.e. macroalgal biomass) in shaping meiofaunal assemblages. Results showed that habitat size (i.e. macroalgal biomass) shaped meiofaunal assemblages influencing its abundance, richness and structure. However, the identity of macroalga (i.e. species) appears also to play a significant role, particularly the differences of complexity among the studied species may shape their meiofaunal assemblages. Finally, the invasive macroalga appears to influence positively species richness. Our results highlight the need of including different faunal components to achieve a comprehensive knowledge on effects of invasive macroalgae and that meiofaunal assemblages may be a valuable tool to examine them.

  11. Mangrove macrobenthos: Assemblages, services, and linkages

    Science.gov (United States)

    Lee, S. Y.

    2008-02-01

    Macrobenthic assemblages are relatively poorly known compared to other components of the mangrove ecosystem. Tropical mangroves support macrobenthic biodiversity resources yet to be properly documented and interpreted. Some methodological challenges, such as the generally high spatial heterogeneity and complexity of the habitat, evidently reduce sampling efficiency and accuracy, while also leaving some microhabitats under-sampled. Macrobenthic assemblage structure seems to be influenced by local environmental conditions, such as hydroperiod, organic matter availability and sediment characteristics. Brachyurans, gastropods and oligochaetes dominate in the sediment, with the former two groups also common on hard surfaces provided by tree trunks, while insects and arachnids inhabit the canopy. Traditionally, studies of mangrove macrobenthos have focused on assemblage structure or the biology of individual species, but more complex inter-specific interactions and the inter-relationship between habitat and the biota are recently being addressed. Brachyuran crabs are the best-studied macrobenthos group, but many issues about their role in mangrove ecosystem dynamics are still controversial. Despite many species of mangrove macrobenthos being referred to as 'trophic dead ends', most serve as important links between recalcitrant mangrove organic matter and estuarine secondary production, through feeding excursion by mobile nekton during the high tide, and macrobenthos-mediated processing and exportation of organic matter. A significant difference in the standing crop biomass of forests between the Indo-west-Pacific (IWP)' and Atlantic-east-Pacific (AEP) mangroves may be related to the difference in species richness of mangrove as well as macrobenthos diversity in the two bioregions. Such differences in assemblage structure may also result in different ecosystem functioning, but the nature of the links is, however, yet to be explored. There is also a strong need for

  12. Ant assemblages in successional stages of Scotch Broom stands

    OpenAIRE

    Dauber, Jens; Simmering, D.

    2006-01-01

    PUBLISHED Scotch Broom (Cytisus scoparius [L.] LINK) stands are important seminatural habitats in cultural landscapes of Ger-many. High structural diversity of broom stands is reflected by a high species diversity of the flora and fauna, giving them a high value for biodiversity conservation. The aim of this study was to assess the composition and structure of ant assemblages among successional stages of Scotch Broom stands, and compare these with assemblages in arable land and the climax ...

  13. Hydrothermal mineralization at Kick'em Jenny submarine volcano in the Lesser Antilles island arc

    Science.gov (United States)

    Olsen, R.; Carey, S.; Sigurdsson, H.; Cornell, W. C.

    2011-12-01

    Kick 'em Jenny (KeJ) is an active submarine volcano located in the Lesser Antilles island arc, ~7.5 km northwest of Grenada. Of the twelve eruptions detected since 1939, most have been explosive as evidenced by eyewitness accounts in 1939, 1974, and 1988 and the dominance of explosive eruption products recovered by dredging. In 2003, vigorous hydrothermal activity was observed in the crater of KeJ. Video footage taken by a remotely operated vehicle (ROV) during the cruise RB-03-03 of the R/V Ronald Brown documented the venting of a vapor phase in the form of bubbles that ascended through the water column and a clear fluid phase in the form of shimmering water. The shimmering water generally ascended through the water column but can also been seen flowing down gradient from a fissure at the top of a fine-grained sediment mound. These fine-grained sediment mounds are the only structure associated with hydrothermal venting; spire or chimney structures were not observed. Hydrothermal venting was also observed coming from patches of coarse-grained volcaniclastic sediment on the crater floor and from talus slopes around the perimeter of the crater. Samples were collected from these areas and from areas void of hydrothermal activity. XRD and ICPMS analyses of bulk sediment were carried out to investigate the geochemical relationships between sediment types. Sediment samples from the hydrothermal mound structures are comprised of the same components (plagioclase, amphibole, pyroxene, and scoria) as sediment samples from areas void of hydrothermal activity (primary volcaniclastic sediment) in the 500-63 μm size range. High resolution grain size analyses show that >78% of sediment in the hydrothermal mound samples are between 63-2 μm with 6-20% clay sized (talc, and I/S mixed layer) in the hydrothermal mound samples was confirmed x-ray diffraction analysis. Differences in major oxide composition of the two sediment types (depletion in Al2O3 but enrichments in MgO and Fe2O3

  14. Genetic Diversity in the Lesser Antilles and Its Implications for the Settlement of the Caribbean Basin

    OpenAIRE

    Benn Torres, Jada; Vilar, Miguel G.; Torres, Gabriel A.; Gaieski, Jill B.; Bharath Hernandez, Ricardo; Browne, Zoila E.; Stevenson, Marlon; Walters, Wendell; Schurr, Theodore G.; ,

    2015-01-01

    Historical discourses about the Caribbean often chronicle West African and European influence to the general neglect of indigenous people’s contributions to the contemporary region. Consequently, demographic histories of Caribbean people prior to and after European contact are not well understood. Although archeological evidence suggests that the Lesser Antilles were populated in a series of northward and eastern migratory waves, many questions remain regarding the relationship of the Caribbe...

  15. Black liquor and the hangover effect: fish assemblage recovery dynamics following a pulse disturbance.

    Science.gov (United States)

    Piller, Kyle R; Geheber, Aaron D

    2015-06-01

    Anthropogenic perturbations impact aquatic systems causing wide-ranging responses, from assemblage restructuring to assemblage recovery. Previous studies indicate the duration and intensity of disturbances play a role in the dynamics of assemblage recovery. In August 2011, the Pearl River, United States, was subjected to a weak black liquor spill from a paper mill which resulted in substantial loss of fish in a large stretch of the main channel. We quantified resilience and recovery of fish assemblage structure in the impacted area following the event. We compared downstream (impacted) assemblages to upstream (unimpacted) assemblages to determine initial impacts on structure. Additionally, we incorporated historic fish collections (1988-2011) to examine impacts on assemblage structure across broad temporal scales. Based on NMDS, upstream and downstream sites generally showed similar assemblage structure across sample periods with the exception of the 2 months postdischarge, where upstream and downstream sites visually differed. Multivariate analysis of variance (PERMANOVA) indicated significant seasonal variation among samples, but found no significant interaction between impacted and unimpacted assemblages following the discharge event. However, multivariate dispersion (MVDISP) showed greater variance among assemblage structure following the discharge event. These results suggest that 2 months following the disturbance represent a time period of stochasticity in regard to assemblage structure dynamics, and this was followed by rapid recovery. We term this dynamic the "hangover effect" as it represents the time frame from the cessation of the perturbation to the assemblage's return to predisturbance conditions. The availability and proximity of tributaries and upstream refugia, which were not affected by the disturbance, as well as the rapid recovery of abiotic parameters likely played a substantial role in assemblage recovery. This study not only demonstrates

  16. Quelle est la contribution des lisières forestières à la structuration des assemblages d’abeilles sauvages dans les paysages agricoles ?

    OpenAIRE

    Bailey, Samantha

    2014-01-01

    Des assemblages de pollinisateurs sauvages plus diversifiés et abondants fourniraient un service de pollinisation plus stable et efficace pour une plus large gamme de cultures. La rupture de l’équilibre entre milieux semi-naturels et anthropisés dans la mosaïque paysagère est souvent invoquée pour expliquer le déclin des pollinisateurs. Le maintien des abeilles sauvages est fortement dépendant de la disponibilité, dans le rayon de dispersion de l’espèce, des ressources floristiques et des mic...

  17. Invertebrate distribution patterns and river typology for the implementation of the water framework directive in Martinique, French Lesser Antilles

    Directory of Open Access Journals (Sweden)

    Bernadet C.

    2013-03-01

    Full Text Available Over the past decade, Europe’s Water Framework Directive provided compelling reasons for developing tools for the biological assessment of freshwater ecosystem health in member States. Yet, the lack of published study for Europe’s overseas regions reflects minimal knowledge of the distribution patterns of aquatic species in Community’s outermost areas. Benthic invertebrates (84 taxa and land-cover, physical habitat and water chemistry descriptors (26 variables were recorded at fifty-one stations in Martinique, French Lesser Antilles. Canonical Correspondence Analysis and Ward’s algorithm were used to bring out patterns in community structure in relation to environmental conditions, and variation partitioning was used to specify the influence of geomorphology and anthropogenic disturbance on invertebrate communities. Species richness decreased from headwater to lowland streams, and species composition changed from northern to southern areas. The proportion of variation explained by geomorphological variables was globally higher than that explained by anthropogenic variables. Geomorphology and land cover played key roles in delineating ecological sub-regions for the freshwater biota. Despite this and the small surface area of Martinique (1080 km2, invertebrate communities showed a clear spatial turnover in composition and biological traits (e.g., insects, crustaceans and molluscs in relation to natural conditions.

  18. Snake assemblages of Marajó Island, Pará state, Brazil

    OpenAIRE

    Gerson Moreira Rodrigues; Gleomar Fabiano Maschio; Ana Lúcia da Costa Prudente

    2016-01-01

    ABSTRACT We describe the diversity, natural history and structure of snake assemblages from Marajó Island, state of Pará, Brazil, after analyzing 439 specimens deposited in herpetological collections. We tested the hypothesis that snake assemblages from forest and open areas of Marajó Island are distinct with regard to their structure, composition and functional groups. To compare the snake composition of the forest and open areas of Marajó with other comparable assemblages in Brazil, Princip...

  19. Differences in stability of seed-associated microbial assemblages in response to invasion by phytopathogenic microorganisms

    OpenAIRE

    Rezki, Samir; Campion, Claire; Iacomi-Vasilescu, Beatrice; Preveaux, Anne; Toualbia, Youness; Bonneau, Sophie; Briand, Martial; Laurent, Emmanuelle; Hunault, Gilles; Simoneau, Philippe; Jacques, Marie Agnes

    2016-01-01

    Seeds are involved in the vertical transmission of microorganisms from one plant generation to another and consequently act as reservoirs for the plant microbiota. However, little is known about the structure of seed-associated microbial assemblages and the regulators of assemblage structure. In this work, we have assessed the response of seed associated microbial assemblages of Raphanus sativus to invading phytopathogenic agents, the bacterial strain Xanthomonas campestris pv. campestris (Xc...

  20. Heat flow in the Lesser Antilles island arc and adjacent back arc Grenada basin

    OpenAIRE

    Manga, Michael; Hornbach, Matthew J.; Friant, Anne Le; Ishizuka, Osamu; Stroncik, Nicole; Adachi, Tatsuya; Aljahdali, Mohammed; Boudon, Georges; Breitkreuz, Christoph; Fraass, Andrew; Fujinawa, Akihiko; Hatfield, Robert; Jutzeler, Martin; Kataoka, Kyoko; Lafuerza, Sara

    2012-01-01

    Using temperature gradients measured in 10 holes at 6 sites, we generate the first high fidelity heat flow measurements from Integrated Ocean Drilling Program drill holes across the northern and central Lesser Antilles arc and back arc Grenada basin. The implied heat flow, after correcting for bathymetry and sedimentation effects, ranges from about 0.1 W/m2 on the crest of the arc, midway between the volcanic islands of Montserrat and Guadeloupe, to 15 km from the crest in the back arc direct...

  1. Beetle species diversity in the Lesser Antilles islands: How many species are really there?

    OpenAIRE

    Peck, Stewart B.

    2009-01-01

    Recent extensive and intensive field work by the team of M. A. Ivie on the Lesser Antillean island of Montserrat suggests that a mean of 827 beetle species may be expected on that island. This datum makes possible the generation of hypotheses of the probable beetle species diversity on other islands of the Lesser Antilles as a function of the areas of the islands. Figures are given for the presently known, estimated total, and estimated number of unknown species for each principal island. Thi...

  2. Hygrophoraceae (Agaricales) of the Greater Antilles: Hygrocybe subgenus Pseudohygrocybe sections Coccineae and Neohygrocybe.

    Science.gov (United States)

    Cantrell, Sharon A; Lodge, D Jean

    2004-11-01

    A key to 17 species in the genus Hygrocybe, subgenus Pseudohygrocybe, sections Coccineae and Neohygrocybe sensu Boertmann is provided for the Greater Antilles. Five new species and five taxa that are new reports for the region are described. The new species in section Coccineae are H. pseudoadonis, H. viridiphylla, and H. zonata. The new species in section Neohygrocybe are H. albomarginata and H. ovinoides. The new reports are H. caespitosa, H. coccinea, H. cf. miniata, H. papillata, and H. subovina. Three new combinations are proposed: Hygrocybe mycenoides, H. papillata and H. subovina. PMID:15587063

  3. Morphostructure at the junction between the Beata ridge and the Greater Antilles island arc (offshore Hispaniola southern slope)

    Science.gov (United States)

    Granja Bruña, J. L.; Carbó-Gorosabel, A.; Llanes Estrada, P.; Muñoz-Martín, A.; ten Brink, U. S.; Gómez Ballesteros, M.; Druet, M.; Pazos, A.

    2014-03-01

    Oblique convergence between the Caribbean plate's interior and the inactive Greater Antilles island arc has resulted in the collision and impingement of the thickened crust of the Beata ridge into southern Hispaniola Island. Deformation resulting from this convergence changes from a low-angle southward-verging thrust south of eastern Hispaniola, to collision and uplift in south-central Hispaniola, and to left-lateral transpression along the Southern peninsula of Haiti in western Hispaniola. Using new swath bathymetry and a dense seismic reflection grid, we mapped the morphological, structural and sedimentological elements of offshore southern Hispaniola. We have identified four morphotectonic provinces: the Dominican sub-basin, the Muertos margin, the Beata ridge and the Haiti sub-basin. The lower slope of the Muertos margin is occupied by the active Muertos thrust belt, which includes several active out-of-sequence thrust faults that, were they to rupture along their entire length, could generate large-magnitude earthquakes. The interaction of the thrust belt with the Beata ridge yields a huge recess and the imbricate system disappears. The upper slope of the Muertos margin shows thick slope deposits where the extensional tectonics and slumping processes predominate. The northern Beata ridge consists of an asymmetrically uplifted and faulted block of oceanic crust. Our results suggest that the shallower structure and morphology of the northern Beata ridge can be mainly explained by a mechanism of extensional unloading from the Upper Cretaceous onward that is still active residually along the summit of the ridge. The tectonic models for the northern Beata ridge involving active reverse strike-slip faults and transpression caused by the oblique convergence between the Beata ridge and the island arc are not supported by the structural interpretation. The eastern Bahoruco slope an old normal fault that acts as a passive tear fault accommodating the sharp along

  4. Sero-epidemiological survey on bovine tick-borne diseases in the Lesser Antilles

    International Nuclear Information System (INIS)

    As part of a tick-borne disease control programme in the Lesser Antilles, studies were undertaken to determine the prevalence of cowdriosis, babesiosis and anaplasmosis in an effort to determine what the impact of tick eradication would be. The epidemiological situation for bovine babesiosis and anaplasmosis is unstable in all the islands of the Lesser Antilles, but the clinical cases are only recorded in imported breeds, which represent less than 5% of the cattle population. The native cattle population react as if naturally resistant. When the A. variegatum tick eradication campaign begins, it will be necessary, by the end of the acaricide treatment regime, to immunize all the imported cattle born during that period, and possibly all of the seronegative imported cattle already on the islands. Both Antigua and Guadeloupe have a long history of infestation with the tick and both have experienced clinical cases of cowdriosis. On the other islands, less than 6% of the sera were positive and this correlates well also with an apparent absence of clinical cases of cowdriosis. (author)

  5. Significant technical advances in broadband seismic stations in the Lesser Antilles

    Science.gov (United States)

    Anglade, A.; Lemarchand, A.; Saurel, J.-M.; Clouard, V.; Bouin, M.-P.; De Chabalier, J.-B.; Tait, S.; Brunet, C.; Nercessian, A.; Beauducel, F.; Robertson, R.; Lynch, L.; Higgins, M.; Latchman, J.

    2015-04-01

    In the last few years, French West Indies observatories from the Institut de Physique du Globe de Paris (IPGP), in collaboration with The UWI Seismic Research Centre (SRC, University of West Indies), have modernized the Lesser Antilles Arc seismic and deformation monitoring network. 15 new, permanent stations have been installed that strengthen and expand its detection capabilities. The global network of the IPGP-SRC consortium is now composed of 20 modernized stations, all equipped with broadband seismometers, strong motion sensors, Global Positioning System (GPS) sensors and satellite communication for real-time data transfer. To enhance the sensitivity and reduce ambient noise, special efforts were made to improve the design of the seismic vault and the original Stuttgart shielding of the broadband seismometers (240 and 120s corner period). Tests were conducted for several months, involving different types of countermeasures, to achieve the highest performance level of the seismometers. GPS data, realtime and validated seismic data (only broadband) are now available from the IPGP data centre (http://centrededonnees.ipgp.fr/index.php?&lang=EN). This upgraded network feeds the Caribbean Tsunami Warning System supported by UNESCO and establishes a monitoring tool that produces high quality data for studying subduction and volcanic processes in the Lesser Antilles arc.

  6. Public Sphere as Digital Assemblage

    DEFF Research Database (Denmark)

    Salovaara-Moring, Inka

    the 1990s onwards digitalization brought concepts of network and complexity into the theoretical discourse. This relational turn changed the social ontology of the public sphere into a dynamic and complex system, erasing the division between the fields of reality (the world), representation (discourse......), and subjectivity (agency). This changed the public sphere into an assemblage consisting of both human and non-human actors interactingin a highly dynamic, networked environment. This paper proposes a framework for considering this new materiality in the field of the public sphere: the assemblage and complexity...

  7. The shallow-water fish assemblage of Isla del Coco National Park, Costa Rica: structure and patterns in an isolated, predator-dominated ecosystem

    Science.gov (United States)

    Friedlander, Alan M.; Zgliczynski, Brian J.; Ballesteros, Enric; Aburto-Oropeza, Octavio; Bolaños, Allan; Sala, Enric

    2012-01-01

    Fishes at Isla del Coco National Park, Costa Rica, were surveyed as part of a larger scientific expedition to the area in September 2009. The average total biomass of nearshore fishes was 7.8 tonnes per ha, among the largest observed in the tropics, with apex predators such as sharks, jacks, and groupers accounting for nearly 40% of the total biomass. The abundance of reef and pelagic sharks, particularly large aggregations of threatened species such as the scalloped hammerhead shark (up to 42 hammerheads ha-1) and large schools of jacks and snappers show the capacity for high biomass in unfished ecosystems in the Eastern Tropical Pacific. However, the abundance of hammerhead and reef whitetip sharks appears to have been declining since the late 1990s, and likely causes may include increasing fishing pressure on sharks in the region and illegal fishing inside the Park. One Galapagos shark tagged on September 20, 2009 in the Isla del Coco National Park moved 255km southeast towards Malpelo Island in Colombia, when it stopped transmitting. These results contribute to the evidence that sharks conduct large-scale movements between marine protected areas (Isla del Coco, Malpelo, Galápagos) in the Eastern tropical Pacific and emphasize the need for regional-scale management. More than half of the species and 90% of the individuals observed were endemic to the tropical eastern Pacific. These high biomass and endemicity values highlight the uniqueness of the fish assemblage at Isla del Coco and its importance as a global biodiversity hotspot.

  8. Do landscape factors affect brownfield carabid assemblages?

    International Nuclear Information System (INIS)

    The carabid fauna of 28 derelict sites in the West Midlands (England) were sampled over the course of one growing season (April-October, 1999). The study aimed to investigate the relationship between carabid assemblages and five measures of landscape structure pertinent to derelict habitat. At each site measurements of landscape features pertinent to derelict habitat were made: (i) the proximity of habitat corridors; (ii) the density of surrounding derelict land; (iii) the distance between the site and the rural fringe; and (iv) the size of the site. Concurrent surveys of the soil characteristics, vegetation type, and land use history were conducted. The data were analysed using a combination of ordination (DCA, RDA), variance partitioning (using pRDA) and binary linear regression. The results suggest that:1.There is very little evidence that the carabid assemblages of derelict sites were affected by landscape structure, with assemblages instead being principally related to within-site habitat variables, such as site age (since last disturbance), substrate type and vegetation community. 2.No evidence was found to support the hypothesis that sites away from railway corridors are more impoverished in their carabid fauna than sites on corridors. 3.There are some suggestions from this study that rarer and non-flying specialist species may be affected by isolation, taking longer to reach sites. We infer from this that older sites with retarded succession, and sites in higher densities of surrounding derelict land may eventually become more species rich and that these sites may be important for maintaining populations of rarer and flightless species. 4.Conservation efforts to maintain populations of these species should focus principally on habitat quality issues, such as maintaining early successional habitats that have a diversity of seed producing annuals and perennial plants and enhancing substrate variability rather than landscape issues

  9. Spatial and temporal variability of mobile macro-invertebrate assemblages associated to coralligenous habitat

    Directory of Open Access Journals (Sweden)

    R. BEDINI

    2014-07-01

    Full Text Available The study aimed to investigate patterns of spatial and temporal variability of mobile macroinvertebrate assemblages associated to coralligenous habitat. A multi-factorial sampling design was used to test the hypotheses that the structure of assemblages and their spatial and temporal variability changed in relation to substrate inclination. Moreover, macroalgae and sessile macro-invertebrates were also investigated in order to detect eventual relationship between sessile and mobile assemblages. A total of 236 mobile macro-invertebrate taxa were identified, among them 2 Platyhelminthes, 4 Sipuncula, 6 Nemertea, 27 Mollusca, 86 Annelida, 103 Arthropoda, 8 Echinodermata. Results of the study showed that mobile macro-invertebrate assemblages of coralligenous habitat were little influenced by the inclination of substrate and by the morphology of sessile organisms, as patterns of variation were different between the two assemblages. Mobile macro-invertebrate assemblages changed among sampling dates within one year period and they showed high variability at the spatial scale examined.

  10. Temporal changes in taxonomic and functional diversity of fish assemblages downstream from mountaintop mining

    Science.gov (United States)

    Hitt, Nathaniel P.; Chambers, Douglas B.

    2014-01-01

    Mountaintop mining (MTM) affects chemical, physical, and hydrological properties of receiving streams, but the long-term consequences for fish-assemblage structure and function are poorly understood. We sampled stream fish assemblages using electrofishing techniques in MTM exposure sites and reference sites within the Guyandotte River basin, USA, during 2010–2011. We calculated indices of taxonomic diversity (species richness, abundance, Shannon diversity) and functional diversity (functional richness, functional evenness, functional divergence) to compare exposure and reference assemblages between seasons (spring and autumn) and across years (1999–2011). We based temporal comparisons on 2 sites that were sampled during 1999–2001 by Stauffer and Ferreri (2002). Exposure assemblages had lower taxonomic and functional diversity than reference assemblages or simulated assemblages that accounted for random variation. Differences in taxonomic composition between reference and exposure assemblages were associated with conductivity and aqueous Se concentrations. Exposure assemblages had fewer species, lower abundances, and less biomass than reference assemblages across years and seasons. Green Sunfish (Lepomis cyanellus) and Creek Chub (Semotilus atromaculatus) became numerically dominant in exposure assemblages over time because of their persistence and losses of other taxa. In contrast, species richness increased over time in reference assemblages, a result that may indicate recovery from drought. Mean individual biomass increased as fish density decreased and most obligate invertivores were apparently extirpated at MTM exposure sites. Effects of MTM were not related to physical-habitat conditions but were associated with water-quality variables, which may limit quality and availability of benthic macroinvertebrate prey. Simulations revealed effects of MTM that could not be attributed to random variation in fish assemblage structure.

  11. A Proposed Community Network For Monitoring Volcanic Emissions In Saint Lucia, Lesser Antilles

    Science.gov (United States)

    Joseph, E. P.; Beckles, D. M.; Robertson, R. E.; Latchman, J. L.; Edwards, S.

    2013-12-01

    Systematic geochemical monitoring of volcanic systems in the English-speaking islands of the Lesser Antilles was initiated by the UWI Seismic Research Centre (SRC) in 2000, as part of its volcanic surveillance programme for the English-speaking islands of the Lesser Antilles. This programme provided the first time-series observations used for the purpose of volcano monitoring in Dominica and Saint Lucia, permitted the characterization of the geothermal fluids associated with them, and established baseline studies for understanding of the hydrothermal systems during periods of quiescence (Joseph et al., 2011; Joseph et al., 2013). As part of efforts to improve and expand the capacity of SRC to provide volcanic surveillance through its geothermal monitoring programme, it is necessary to develop economically sustainable options for the monitoring of volcanic emissions/pollutants. Towards this effort we intend to work in collaboration with local authorities in Saint Lucia, to develop a monitoring network for quantifying the background exposure levels of ambient concentrations of volcanic pollutants, SO2 in air and As in waters (as health significant marker elements in the geothermal emissions) that would serve as a model for the emissions monitoring network for other volcanic islands. This programme would facilitate the building of local capacity and training to monitor the hazardous exposure, through the application and transfer of a regionally available low-cost and low-technology SO2 measurement/detection system in Saint Lucia. Existing monitoring technologies to inform evidence based health practices are too costly for small island Caribbean states, and no government policies or health services measures currently exist to address/mitigate these influences. Gases, aerosols and toxic elements from eruptive and non-eruptive volcanic activity are known to adversely affect human health and the environment (Baxter, 2000; Zhang et al., 2008). Investigations into the

  12. Observed and estimated economic losses in Guadeloupe (French Antilles) after Les Saintes Earthquake (2004). Application to risk comparison

    Science.gov (United States)

    Monfort, Daniel; Reveillère, Arnaud; Lecacheux, Sophie; Muller, Héloise; Grisanti, Ludovic; Baills, Audrey; Bertil, Didier; Sedan, Olivier; Tinard, Pierre

    2013-04-01

    The main objective of this work is to compare the potential direct economic losses between two different hazards in Guadeloupe (French Antilles), earthquakes and storm surges, for different return periods. In order to validate some hypotheses which are done concerning building typologies and their insured values a comparison between real economic loss data and estimated ones is done using a real event. In 2004 there was an earthquake in Guadeloupe, Mw 6.3, in a little archipelago in the south of Guadeloupe called Les Saintes. The heaviest intensities were VIII in the municipalities of Les Saintes and decreases from VII to IV in the other municipalities of Guadeloupe. The CCR, French Reinsurance Organism, has provided data about the total insured economic losses estimated per municipality (in a situation in 2011) and the insurance penetration ratio, it means, the ratio of insured exposed elements per municipality. Some other information about observed damaged structures is quite irregular all over the archipelago, being the only reliable one the observed macroseismic intensity per municipality (field survey done by BCSF). These data at Guadeloupe's scale has been compared with results coming from a retro damage scenario for this earthquake done with the vulnerability data from current buildings and their mean economic value of each building type and taking into account the local amplification effects on the earthquake propagation. In general the results are quite similar but with some significant differences. The results coming from scenario are quite correlated with the spatial attenuation from the earthquake intensity; the heaviest economic losses are concentrated within the municipalities exposed to a considerable and damageable intensity (VII to VIII). On the other side, CCR data show that heavy economic damages are not only located in the most impacted cities but also in the most important municipalities of the archipelago in terms of economic activity

  13. The shallow-water fish assemblage of Isla del Coco National Park, Costa Rica: structure and patterns in an isolated, predator-dominated ecosystem

    Directory of Open Access Journals (Sweden)

    Alan M. Friedlander

    2012-11-01

    Full Text Available Fishes at Isla del Coco National Park, Costa Rica, were surveyed as part of a larger scientific expedition to the area in September 2009. The average total biomass of nearshore fishes was 7.8 tonnes per ha, among the largest observed in the tropics, with apex predators such as sharks, jacks, and groupers accounting for nearly 40% of the total biomass. The abundance of reef and pelagic sharks, particularly large aggregations of threatened species such as the scalloped hammerhead shark (up to 42 hammerheads ha-1 and large schools of jacks and snappers show the capacity for high biomass in unfished ecosystems in the Eastern Tropical Pacific. However, the abundance of hammerhead and reef whitetip sharks appears to have been declining since the late 1990s, and likely causes may include increasing fishing pressure on sharks in the region and illegal fishing inside the Park. One Galapagos shark tagged on September 20, 2009 in the Isla del Coco National Park moved 255km southeast towards Malpelo Island in Colombia, when it stopped transmitting. These results contribute to the evidence that sharks conduct large-scale movements between marine protected areas (Isla del Coco, Malpelo, Galápagos in the Eastern tropical Pacific and emphasize the need for regional-scale management. More than half of the species and 90% of the individuals observed were endemic to the tropical eastern Pacific. These high biomass and endemicity values highlight the uniqueness of the fish assemblage at Isla del Coco and its importance as a global biodiversity hotspot.La biomasa promedio de peces costeros en el Parque Nacional Isla del Coco en septiembre de 2010 fue de 7,8 toneladas por hectárea, entre las más elevadas halladas jamás en zonas tropicales. Los grandes depredadores representaron el 40% de la biomasa total. La abundancia de tiburones costeros y pelágicos, particularmente las enormes agregaciones de tiburón martillo (hasta 42 individuos por hectárea y los

  14. The historic reality of the cyclonic variability in French Antilles, 1635–2007

    Directory of Open Access Journals (Sweden)

    E. Garnier

    2015-04-01

    Full Text Available Facing climate change and increasing costs of natural disasters, the exposure evolution analysis requires having a long-term knowledge of the impacts of extreme events. By associating historical and modeling approaches, we aim to build a long term chronology of natural disaster severity and damages. To highlight this new methodology, the overseas departments of French Antilles have been chosen. These territories are strongly exposed to natural disasters, particularly hurricanes. The search with historical archives made it possible to reconstruct, for the first time, the chronology and severity of hurricanes since the 17th century. During the 20th century, a significative increase in the number of cyclones has occurred after the 1950s. The analysis of a longer historical period (since the 1630s allows us to temperate this idea by showing intensive cyclonic period in the past centuries.

  15. What is important for ant assemblages in temperate forest soils?

    Directory of Open Access Journals (Sweden)

    Tae-Sung Kwon

    2016-06-01

    Full Text Available Ant assemblages in the soil have been studied at eight forest sites (4 oak forest sites, and 4 pine forest sites in four study areas (1 seminatural area, and 3 industrialized areas in South Korea for 6 years from 2002 to 2010. Soil cores and Tullgren funnel were used for the ant survey. Ant surveys were carried out once per year in autumn (from late September to mid-October. The soil pH was lower in the industrialized than in the seminatural area, showing the acidified soils in the industrialized areas. However, the soil acidification did not influence the ant assemblages. The results from the nonmetric multidimensional scaling ordination and from the community temperature index values indicate that temperature is a key determinant for structures of the soil ant assemblages. The ant assemblages were not different according to the forest types (oak forests vs. pine forests. Occurrence of ant species varied greatly among years, indicating that more replicates and advanced sampling method are needed for the monitoring of the soil ant assemblages.

  16. Status and conservation of parrots and parakeets in the Greater Antilles, Bahama Islands, and Cayman Islands

    Science.gov (United States)

    Wiley, J.W.

    1991-01-01

    In the 1490s a minimum of 28 species of psittacines occurred in the West Indies. Today, only 43% (12) of the species survive. All macaws and most parakeet species have been lost. Although the surviving parrot fauna of the Greater Antilles, Cayman Islands, and Bahama Islands has fared somewhat better than that of the Lesser Antilles, every species has undergone extensive reductions of populations and all but two have undergone extensive reductions in range, mostly as a result of habitat loss, but also from persecution as agricultural pests, conflicts with exotic species, harvesting for pets, and natural disasters. The Cayman Brac Parrot Amazona leucocephala hesterna with its tiny population (less than 150 individuals in the wild) and range, and the Puerto Rican Parrot A. vittata, with about 22-23 birds in the wild and 56 individuals in captivity, must be considered on the verge of extinction and in need of (in the latter's case, continuing) aggressive programmes of research and management. Other populations declining in numbers and range include the Yellow-billed Amazona collaria, and Black-billed A. agilis Parrots of Jamaica, Hispaniolan Parakeet Aratinga chloroptera, Hispaniolan Parrot Amazona ventralis, Cuban Parrot A. leucocephala leucocephala and, most seriously, Cuban Parakeet Aratinga euops. The population of the Grand Cayman Parrot (Amazona leucocephala caymanensis), although numbering only about 1,000 birds, appears stable and the current conservation programme gives hope for the survival of the race. An active conservation and public education programme has begun for the Bahama Parrot A. l. bahamensis, which still occurs in good numbers on Great Inagua Island, but is threatened on Abaco Island. Recommendations for conservation of parrots and parakeets in the region include (1) instituting long-term programmes of research to determine distribution, status, and ecology of each species; (2) developing conservation programmes through education and management

  17. Habitat specialization in tropical continental shelf demersal fish assemblages.

    Directory of Open Access Journals (Sweden)

    Ben M Fitzpatrick

    Full Text Available The implications of shallow water impacts such as fishing and climate change on fish assemblages are generally considered in isolation from the distribution and abundance of these fish assemblages in adjacent deeper waters. We investigate the abundance and length of demersal fish assemblages across a section of tropical continental shelf at Ningaloo Reef, Western Australia, to identify fish and fish habitat relationships across steep gradients in depth and in different benthic habitat types. The assemblage composition of demersal fish were assessed from baited remote underwater stereo-video samples (n = 304 collected from 16 depth and habitat combinations. Samples were collected across a depth range poorly represented in the literature from the fringing reef lagoon (1-10 m depth, down the fore reef slope to the reef base (10-30 m depth then across the adjacent continental shelf (30-110 m depth. Multivariate analyses showed that there were distinctive fish assemblages and different sized fish were associated with each habitat/depth category. Species richness, MaxN and diversity declined with depth, while average length and trophic level increased. The assemblage structure, diversity, size and trophic structure of demersal fishes changes from shallow inshore habitats to deeper water habitats. More habitat specialists (unique species per habitat/depth category were associated with the reef slope and reef base than other habitats, but offshore sponge-dominated habitats and inshore coral-dominated reef also supported unique species. This suggests that marine protected areas in shallow coral-dominated reef habitats may not adequately protect those species whose depth distribution extends beyond shallow habitats, or other significant elements of demersal fish biodiversity. The ontogenetic habitat partitioning which is characteristic of many species, suggests that to maintain entire species life histories it is necessary to protect corridors of

  18. Light-dependant biostabilisation of sediments by stromatolite assemblages.

    Directory of Open Access Journals (Sweden)

    David M Paterson

    Full Text Available For the first time we have investigated the natural ecosystem engineering capacity of stromatolitic microbial assemblages. Stromatolites are laminated sedimentary structures formed by microbial activity and are considered to have dominated the shallows of the Precambrian oceans. Their fossilised remains are the most ancient unambiguous record of early life on earth. Stromatolites can therefore be considered as the first recognisable ecosystems on the planet. However, while many discussions have taken place over their structure and form, we have very little information on their functional ecology and how such assemblages persisted despite strong eternal forcing from wind and waves. The capture and binding of sediment is clearly a critical feature for the formation and persistence of stromatolite assemblages. Here, we investigated the ecosystem engineering capacity of stromatolitic microbial assemblages with respect to their ability to stabilise sediment using material from one of the few remaining living stromatolite systems (Highborne Cay, Bahamas. It was shown that the most effective assemblages could produce a rapid (12-24 h and significant increase in sediment stability that continued in a linear fashion over the period of the experimentation (228 h. Importantly, it was also found that light was required for the assemblages to produce this stabilisation effect and that removal of assemblage into darkness could lead to a partial reversal of the stabilisation. This was attributed to the breakdown of extracellular polymeric substances under anaerobic conditions. These data were supported by microelectrode profiling of oxygen and calcium. The structure of the assemblages as they formed was visualised by low-temperature scanning electron microscopy and confocal laser microscopy. These results have implications for the understanding of early stromatolite development and highlight the potential importance of the evolution of photosynthesis in the

  19. Environmental variables measured at multiple spatial scales exert uneven influence on fish assemblages of floodplain lakes

    Science.gov (United States)

    Dembkowski, Daniel J.; Miranda, Leandro E.

    2014-01-01

    We examined the interaction between environmental variables measured at three different scales (i.e., landscape, lake, and in-lake) and fish assemblage descriptors across a range of over 50 floodplain lakes in the Mississippi Alluvial Valley of Mississippi and Arkansas. Our goal was to identify important local- and landscape-level determinants of fish assemblage structure. Relationships between fish assemblage structure and variables measured at broader scales (i.e., landscape-level and lake-level) were hypothesized to be stronger than relationships with variables measured at finer scales (i.e., in-lake variables). Results suggest that fish assemblage structure in floodplain lakes was influenced by variables operating on three different scales. However, and contrary to expectations, canonical correlations between in-lake environmental characteristics and fish assemblage structure were generally stronger than correlations between landscape-level and lake-level variables and fish assemblage structure, suggesting a hierarchy of influence. From a resource management perspective, our study suggests that landscape-level and lake-level variables may be manipulated for conservation or restoration purposes, and in-lake variables and fish assemblage structure may be used to monitor the success of such efforts.

  20. Spatio-temporal variability in ontogenetic guild structure of an intertidal fish assemblage in central Chile Variabilidad espacio-temporal en la estructura de gremios ontogenéticos de un ensamble de peces intermareales de Chile central

    Directory of Open Access Journals (Sweden)

    PATRICIA A BERRÍOS

    2011-12-01

    Full Text Available Species resource use can vary throughout ontogeny, potentially affecting community dynamics. This can be particularly important for species facing high variability in environmental conditions and going through several orders of magnitude in size, as intertidal fishes. However, the influence of the resulting ontogenetic changes in guild membership on the spatio-temporal structure of fish assemblages remains virtually unknown. Here we assessed the spatial and temporal variability in the ontogenetic feeding guild (OFG structure of the fish assemblage inhabiting the temperate rocky intertidal zone along central Chilean coast. This was done applying principal component analysis (PCA and randomization tests (R-test on the relative OFG composition of fish assemblages, obtained from seasonal samples from ten pools located at two heights in the intertidal zone in three localities between 33° and 34° S. Overall, the PCA and R-tests suggest that spatial variability dominated over temporal variability in OFG structure, mainly due to a higher representation of omnivore species at high intertidal pools in two of the three sampled localities. However, phenology-related changes in the representation of fish size-classes (i.e. carnivore recruitment in spring-summer along with ontogenetic differences in habitat selection (e.g., selection for low intertidal pools by bigger-sized carnivore OFG contributed to both spatial and temporal differentiation in OFG structure. Finally, the relative representation of each OFG correlated with that of their dominant species, without evidence for density compensation. This suggests low levels of functional redundancy among species in each OFG, highlighting the vulnerability of assemblage functioning to size-biased disturbances as fishing.El uso de los recursos puede variar a través de la ontogenia, afectando potencialmente las dinámicas comunitarias. Esto puede ser de particular importancia en especies que enfrentan alta

  1. Phytoplankton Assemblage Patterns in the Southern Mid-Atlantic Bight

    Science.gov (United States)

    Makinen, Carla; Moisan, Tiffany A. (Editor)

    2012-01-01

    As part of the Wallops Coastal Oceans Observing Laboratory (Wa-COOL) Project, we sampled a time-series transect in the southern Mid-Atlantic Bight (MAB) biweekly. Our 2-year time-series data included physical parameters, nutrient concentrations, and chlorophyll a concentrations. A detailed phytoplankton assemblage structure was examined in the second year. During the 2-year study, chlorophyll a concentration (and ocean color satellite imagery) indicated that phytoplankton blooms occurred in January/February during mixing conditions and in early autumn under stratified conditions. The chlorophyll a concentrations ranged from 0.25 microgram 1(exp -1) to 15.49 microgram 1(exp -1) during the 2-year period. We were able to discriminate approximately 116 different species under phase contrast microscopy. Dominant phytoplankton included Skeletonema costatum, Rhizosolenia spp., and Pseudo-nitzschia pungens. In an attempt to determine phytoplankton species competition/succession within the assemblage, we calculated a Shannon Weaver diversity index for our diatom microscopy data. Diatom diversity was greatest during the winter and minimal during the spring. Diatom diversity was also greater at nearshore stations than at offshore stations. Individual genera appeared patchy, with surface and subsurface patches appearing abruptly and persisting for only 1-2 months at a time. The distribution of individual species differed significantly from bulk variables of the assemblage (chlorophyll a ) and total phytoplankton assemblage (cells), which indicates that phytoplankton species may be limited in growth in ways that differ from those of the total assemblage. Our study demonstrated a highly diverse phytoplankton assemblage throughout the year, with opportunistic species dominating during spring and fall in response to seasonal changes in temperature and nutrients in the southern MAB.

  2. Viral assemblage composition in Yellowstone acidic hot springs assessed by network analysis.

    Science.gov (United States)

    Bolduc, Benjamin; Wirth, Jennifer F; Mazurie, Aurélien; Young, Mark J

    2015-10-01

    Understanding of viral assemblage structure in natural environments remains a daunting task. Total viral assemblage sequencing (for example, viral metagenomics) provides a tractable approach. However, even with the availability of next-generation sequencing technology it is usually only possible to obtain a fragmented view of viral assemblages in natural ecosystems. In this study, we applied a network-based approach in combination with viral metagenomics to investigate viral assemblage structure in the high temperature, acidic hot springs of Yellowstone National Park, USA. Our results show that this approach can identify distinct viral groups and provide insights into the viral assemblage structure. We identified 110 viral groups in the hot springs environment, with each viral group likely representing a viral family at the sub-family taxonomic level. Most of these viral groups are previously unknown DNA viruses likely infecting archaeal hosts. Overall, this study demonstrates the utility of combining viral assemblage sequencing approaches with network analysis to gain insights into viral assemblage structure in natural ecosystems. PMID:26125684

  3. Halogen content in Lesser Antilles arc volcanic rocks : exploring subduction recycling

    Science.gov (United States)

    Thierry, Pauline; Villemant, Benoit; Caron, Benoit

    2016-04-01

    Halogens (F, Cl, Br and I) are strongly reactive volatile elements which can be used as tracers of igneous processes, through mantle melting, magma differentiation and degassing or crustal material recycling into mantle at subduction zones. Cl, Br and I are higly incompatible during partial melting or fractional cristallization and strongly depleted in melts by H2O degassing, which means that no Cl-Br-I fractionation is expected through magmatic differenciation [current thesis]. Thus, Cl/Br/I ratios in lavas reflect the halogen content of their mantle sources. Whereas these ratios seemed quite constant (e.g. Cl/Br =300 as seawater), recent works suggest significant variations in arc volcanism [1,2]. In this work we provide high-precision halogen measurements in volcanic rocks from the recent activity of the Lesser Antilles arc (Montserrat, Martinique, Guadeloupe, Dominique). Halogen contents of powdered samples were determined through extraction in solution by pyrohydrolysis and analysed by Ion Chromatography for F and Cl and high performance ICP-MS (Agilent 8800 Tripe Quad) for Cl, Br and I [3,4]. We show that lavas - and mantle sources - display significant vraiations in Cl/Br/I ratios along the Lesser Antilles arc. These variations are compared with Pb, Nd and Sr isotopes and fluid-mobile elements (Ba, U, Sr, Pb etc.) compositions which vary along the arc from a nothern ordinary arc compositions to a southern 'crustal-like' composition [5,6]. These characteristics are attributed to subducted sediments recycling into the mantle wedge, whose contribution vary along the arc from north to south [7,8]. The proportion of added sediments is also related to the distance to the trench as sediment melting and slab dehydration may occur depending on the slab depth [9]. Further Cl-Br-I in situ measurements by LA-ICP-MS in Lesser Antilles arc lavas melt inclusions will be performed, in order to provide better constraints on the deep halogen recycling cycle from crust to

  4. Active faulting induced by the slip partitioning in the Lesser Antilles arc

    Science.gov (United States)

    Leclerc, Frédérique; Feuillet, Nathalie

    2010-05-01

    AGUADOMAR marine cruise data acquired 11 years ago allowed us to identified and map two main sets of active faults within the Lesser Antilles arc (Feuillet et al., 2002; 2004). The faults belonging to the first set, such as Morne-Piton in Guadeloupe, bound up to 100km-long and 50km-wide arc-perpendicular graben or half graben that disrupt the fore-arc reef platforms. The faults of the second set form right-stepping en echelon arrays, accommodating left-lateral slip along the inner, volcanic islands. The two fault systems form a sinistral horsetail east of the tip of the left-lateral Puerto Rico fault zone that takes up the trench-parallel component of convergence between the North-American and Caribbean plates west of the Anegada passage. In other words, they together accommodate large-scale slip partitioning along the northeastern arc, consistent with recent GPS measurements (Lopez et al., 2006). These intraplate faults are responsible for a part of the shallow seismicity in the arc and have produce damaging historical earthquakes. Two magnitude 6.3 events occurred in the last 25 years along the inner en echelon faults, the last one on November 21 2004 in Les Saintes in the Guadeloupe archipelago. To better constrain the seismic hazard related to the inner arc faults and image the ruptures and effects on the seafloor of Les Saintes 2004 earthquake, we acquired new marine data between 23 February and 25 March 2009 aboard the French R/V le Suroît during the GWADASEIS cruise. We present here the data (high-resolution 72 channel and very high-resolution chirp 3.5 khz seismic reflection profiles, EM300 multibeam bathymetry, Küllenberg coring and SAR imagery) and the first results. We identified, mapped and characterized in detail several normal to oblique fault systems between Martinique and Saba. They offset the seafloor by several hundred meters and crosscut all active volcanoes, among them Nevis Peak, Soufriere Hills, Soufriere de Guadeloupe and Montagne Pel

  5. Long-distance multistep sediment transfer at convergent plate margins (Barbados, Lesser Antilles)

    Science.gov (United States)

    Limonta, Mara; Garzanti, Eduardo; Resentini, Alberto; Andò, Sergio; Boni, Maria; Bechstädt, Thilo

    2015-04-01

    We present a regional provenance study of the compositional variability and long distance multicyclic transport of terrigenous sediments along the convergent and transform plate boundaries of Central America, from the northern termination of the Andes to the Lesser Antilles arc-trench system. We focus on high-resolution bulk-petrography and heavy-mineral analyses of modern beach and fluvial sediments and Cenozoic sandstones of Barbados island, one of the places in the world where an active accretionary prism is subaerially exposed (Speed et al., 2012). The main source of siliciclastic sediment in the Barbados accretionary prism is off-scraped quartzose to feldspatho-litho-quartzose metasedimentaclastic turbidites, ultimately supplied from South America chiefly via the Orinoco fluvio-deltaic system. Modern sand on Barbados island is either quartzose with depleted heavy-mineral suites recycled from Cenozoic turbidites and including epidote, zircon, tourmaline, andalusite, garnet, staurolite and chloritoid, or calcareous and derived from Pleistocene coral reefs. The ubiquitous occurrence of clinopyroxene and hypersthene, associated with green-brown kaersutitic hornblende in the north or olivine in the south, points to reworking of ash-fall tephra erupted from andesitic (St. Lucia) and basaltic (St. Vincent) volcanic centers in the Lesser Antilles arc transported by the prevailing anti-trade winds in the upper troposphere. Modern sediments on Barbados island and those shed by other accretionary prisms such as the Indo- Burman Ranges and Andaman-Nicobar Ridge (Garzanti et al., 2013) define the distinctive mineralogical signature of Subduction Complex Provenance, which is invariably composite. Detritus recycled dominantly from accreted turbidites and oceanic mudrocks is mixed in various proportions with detritus from the adjacent volcanic arc or carbonate reefs widely developed at tropical latitudes. Ophiolitic detritus may be locally prominent. Quantitative provenance

  6. New Perspective of Tsunami Deposit Investigations: Insight from the 1755 Lisbon Tsunami in Martinique, Lesser Antilles.

    Science.gov (United States)

    Roger, J.; Clouard, V.; Moizan, E.

    2014-12-01

    The recent devastating tsunamis having occurred during the last decades have highlighted the essential necessity to deploy operationnal warning systems and educate coastal populations. This could not be prepared correctly without a minimum knowledge about the tsunami history. That is the case of the Lesser Antilles islands, where a few handfuls of tsunamis have been reported over the past 5 centuries, some of them leading to notable destructions and inundations. But the lack of accurate details for most of the historical tsunamis and the limited period during which we could find written information represents an important problem for tsunami hazard assessment in this region. Thus, it is of major necessity to try to find other evidences of past tsunamis by looking for sedimentary deposits. Unfortunately, island tropical environments do not seem to be the best places to keep such deposits burried. In fact, heavy rainfalls, storms, and all other phenomena leading to coastal erosion, and associated to human activities such as intensive sugarcane cultivation in coastal flat lands, could caused the loss of potential tsunami deposits. Lots of places have been accurately investigated within the Lesser Antilles (from Sainte-Lucia to the British Virgin Islands) the last 3 years and nothing convincing has been found. That is when archeaological investigations excavated a 8-cm thick sandy and shelly layer in downtown Fort-de-France (Martinique), wedged between two well-identified layers of human origin (Fig. 1), that we found new hope: this sandy layer has been quickly attributed without any doubt to the 1755 tsunami, using on one hand the information provided by historical reports of the construction sites, and on the other hand by numerical modeling of the tsunami (wave heights, velocity fields, etc.) showing the ability of this transoceanic tsunami to wrap around the island after ~7 hours of propagation, enter Fort-de-France's Bay with enough energy to carry sediments, and

  7. Slip partitioning in the Lesser Antilles arc: implications for seismic and volcanic hazards

    Science.gov (United States)

    Feuillet, N.; Leclerc, F.; Deplus, C.; Tapponnier, P.; Beauducel, F.; Jacques, E.; Beck, C.; Le Friant, A.; Boudon, G.; LeBrun, J.; Bazin, S.

    2012-12-01

    The Lesser Antilles arc is a region of high seismic and volcanic hazards exposed to large megathrust earthquakes along the subduction zone, to more local events within the arc and to destructive eruptions as in 1902 at Mount Pelee or in 1995 at Soufriere Hills of Montserrat. On November 21, 2004, the Guadeloupe archipelago was struck by a magnitude 6.3 superficial and very damaging earthquake. To better constrain the mechanisms of the recent deformation within the arc and its link with volcanic activity, several marine cruises were conducted since 1998 (AGUADOMAR, GWADASEIS and BATHYSAINTES). A lot of high-resolution data were acquired: Bathymetry, back-scatter images, Küllenberg cores, seismic reflection and chirp profiles. By combining them with onshore data, observations and measurements in the field, we have documented at several scales the active faulting between St Lucia and Saba, the northernmost emerged volcano of the arc. We have shown that the Lesser Antilles arc is crosscut by two main fault sets: arc perpendicular graben in the outer arc and a large en echelon system along the inner active arc. Volcanic complexes are crosscut by or emplaced within fault systems implying that faulting controls the emission of volcanic products. The Nevis volcano is growing on the hanging-wall of a large NE-dipping offshore normal fault probably responsible for the M6+ 1961 earthquake. Montserrat volcanic domes are aligned along a fissure set, parallel to large normal faults and Soufriere of Guadeloupe lies at the western tip of the Marie-Galante graben. At plate scale, the arc perpendicular fore arc graben and inner arc en echelon system are connected, forming a sinistral horsetail, east of the tip of the left lateral Puerto Rico fault zone that takes up the trench parallel component of convergence between the North American and Caribbean plates, west of the Anegada passage. Considering the newly published Caribbean North American Euler vector, the trench parallel

  8. Temporal patterns of diversity: Assessing the biotic and abiotic controls on ant assemblages

    Science.gov (United States)

    Dunn, R.R.; Parker, C.R.; Sanders, N.J.

    2007-01-01

    In this study, we use 12 months of data from 11 ant assemblages to test whether seasonal variation in ant diversity is governed by either the structuring influences of interspecific competition or environmental conditions. Because the importance of competition might vary along environmental gradients, we also test whether the signature of competition depends on elevation. We find little evidence that competition structures the seasonal patterns of activity in the ant assemblages considered, but find support for the effects of temperature on seasonal patterns of diversity, especially at low-elevation sites. Although, in general, both competition and the environment interact to structure ant assemblages, our results suggest that environmental conditions are the primary force structuring the seasonal activity of the ant assemblages studied here. ?? 2007 The Linnean Society of London.

  9. Differences in stability of seed-associated microbial assemblages in response to invasion by phytopathogenic microorganisms

    Science.gov (United States)

    Rezki, Samir; Campion, Claire; Iacomi-Vasilescu, Beatrice; Preveaux, Anne; Toualbia, Youness; Bonneau, Sophie; Briand, Martial; Laurent, Emmanuelle; Hunault, Gilles; Simoneau, Philippe; Jacques, Marie-Agnès

    2016-01-01

    Seeds are involved in the vertical transmission of microorganisms from one plant generation to another and consequently act as reservoirs for the plant microbiota. However, little is known about the structure of seed-associated microbial assemblages and the regulators of assemblage structure. In this work, we have assessed the response of seed-associated microbial assemblages of Raphanus sativus to invading phytopathogenic agents, the bacterial strain Xanthomonas campestris pv. campestris (Xcc) 8004 and the fungal strain Alternaria brassicicola Abra43. According to the indicators of bacterial (16S rRNA gene and gyrB sequences) and fungal (ITS1) diversity employed in this study, seed transmission of the bacterial strain Xcc 8004 did not change the overall composition of resident microbial assemblages. In contrast seed transmission of Abra43 strongly modified the richness and structure of fungal assemblages without affecting bacterial assemblages. The sensitivity of seed-associated fungal assemblage to Abra43 is mostly related to changes in relative abundance of closely related fungal species that belong to the Alternaria genus. Variation in stability of the seed microbiota in response to Xcc and Abra43 invasions could be explained by differences in seed transmission pathways employed by these micro-organisms, which ultimately results in divergence in spatio-temporal colonization of the seed habitat. PMID:27077013

  10. Differences in stability of seed-associated microbial assemblages in response to invasion by phytopathogenic microorganisms.

    Science.gov (United States)

    Rezki, Samir; Campion, Claire; Iacomi-Vasilescu, Beatrice; Preveaux, Anne; Toualbia, Youness; Bonneau, Sophie; Briand, Martial; Laurent, Emmanuelle; Hunault, Gilles; Simoneau, Philippe; Jacques, Marie-Agnès; Barret, Matthieu

    2016-01-01

    Seeds are involved in the vertical transmission of microorganisms from one plant generation to another and consequently act as reservoirs for the plant microbiota. However, little is known about the structure of seed-associated microbial assemblages and the regulators of assemblage structure. In this work, we have assessed the response of seed-associated microbial assemblages of Raphanus sativus to invading phytopathogenic agents, the bacterial strain Xanthomonas campestris pv. campestris (Xcc) 8004 and the fungal strain Alternaria brassicicola Abra43. According to the indicators of bacterial (16S rRNA gene and gyrB sequences) and fungal (ITS1) diversity employed in this study, seed transmission of the bacterial strain Xcc 8004 did not change the overall composition of resident microbial assemblages. In contrast seed transmission of Abra43 strongly modified the richness and structure of fungal assemblages without affecting bacterial assemblages. The sensitivity of seed-associated fungal assemblage to Abra43 is mostly related to changes in relative abundance of closely related fungal species that belong to the Alternaria genus. Variation in stability of the seed microbiota in response to Xcc and Abra43 invasions could be explained by differences in seed transmission pathways employed by these micro-organisms, which ultimately results in divergence in spatio-temporal colonization of the seed habitat. PMID:27077013

  11. Depth as an organizer of fish assemblages in floodplain lakes

    Science.gov (United States)

    Miranda, L.E.

    2011-01-01

    Depth reduction is a natural process in floodplain lakes, but in many basins has been accelerated by anthropogenic disturbances. A diverse set of 42 floodplain lakes in the Yazoo River Basin (Mississippi, USA) was examined to test the hypothesis of whether depth reduction was a key determinant of water quality and fish assemblage structure. Single and multiple variable analyses were applied to 10 commonly monitored water variables and 54 fish species. Results showed strong associations between depth and water characteristics, and between depth and fish assemblages. Deep lakes provided less variable environments, clearer water, and a wider range of microhabitats than shallow lakes. The greater environmental stability was reflected by the dominant species in the assemblages, which included a broader representation of large-body species, species less tolerant of extreme water quality, and more predators. Stability in deep lakes was further reflected by reduced among-lake variability in taxa representation. Fish assemblages in shallow lakes were more variable than deep lakes, and commonly dominated by opportunistic species that have early maturity, extended breeding seasons, small adult size, and short lifespan. Depth is a causal factor that drives many physical and chemical variables that contribute to organizing fish assemblages in floodplain lakes. Thus, correlations between fish and water transparency, temperature, oxygen, trophic state, habitat structure, and other environmental descriptors may ultimately be totally or partly regulated by depth. In basins undergoing rapid anthropogenic modifications, local changes forced by depth reductions may be expected to eliminate species available from the regional pool and could have considerable ecological implications. ?? 2010 Springer Basel AG (outside the USA).

  12. Habitat characteristics and environmental parameters influencing fish assemblages of karstic pools in southern Mexico

    OpenAIRE

    María Eugenia Vega-Cendejas; Mirella Hernandez de Santillana; Steven Norris

    2013-01-01

    Fish assemblage structure was evaluated and compared among 36 karstic pools located within protected areas of the Calakmul Biosphere Reserve (southern Mexico) and unprotected adjacent areas beyond the Reserve. Nonmetric multidimensional scaling (MDS), indicator species analysis (ISA), and canonical correspondence analysis (CCA) were used to identify which environmental factors reflected local influences and to evaluate the correlation of these variables with fish assemblages structure. Thirty...

  13. Response of Macroarthropod Assemblages to the Loss of Hemlock (Tsuga canadensis), a Foundation Species

    OpenAIRE

    Baiser, Benjamin H.; Record, Sydne; Ellison, Aaron M.; Sackett, Tara E.; Bewick, Sharon; Sanders, Nathan J.

    2011-01-01

    In eastern North American forests, eastern hemlock (Tsuga canadensis) is a foundation species. As hemlock is lost from forests due to the invasive hemlock woolly adelgid (Adelges tsugae) and pre-emptive salvage logging, the structure of assemblages of species associated with hemlock is expected to change. We manipulated hemlock canopy structure at hectare scales to investigate the effects of hemlock death on assemblages of ants, beetles, and spiders in a New England forest. Relative to refere...

  14. Nestedness of snake assemblages on islands of an inundated lake

    Institute of Scientific and Technical Information of China (English)

    Yanping WANG; Xi WANG; Ping DING

    2012-01-01

    Nestedness is a pattern frequently reported for faunal assemblages in fragmented systems.Although nestedness has been documented for a wide range of taxa,it is rarely tested in snake assemblages.To arrive at robust generalizations about processes and mechanisms structuring island biotas,it is important to examine under-represented taxa such as snakes for the insights they may offer.We tested for the existence of nestedness and underlying causal mechanisms using snake data collected on islands in the Thousand Island Lake,China.We used the line-transect method to survey snake occupancy and abundance on 20 islands during two breeding seasons in 2009 and 2010.We used the recently developed metric WNODF to estimate nestedness.We used Spearman rank correlations to examine the associations of nestedness and habitat variables (area,isolation,and habitat diversity) as well as life-history traits (body size,clutch size,geographical range size and area requirement) related to species extinction and immigration tendencies.Snake assemblages were significantly nested and were shaped by extinction processes mediated through area effects and habitat nestedness.The nestedness of snake assemblages was not due to passive sampling or selective colonization.From a conservation viewpoint,our results indicate that we should protect both the largest island with the most species-rich community and habitat-rich islands to maximize the number of species preserved.

  15. Nestedness of snake assemblages on islands of an inundated lake

    Directory of Open Access Journals (Sweden)

    Yanping WANG, Xi WANG, Ping DING

    2012-06-01

    Full Text Available Nestedness is a pattern frequently reported for faunal assemblages in fragmented systems. Although nestedness has been documented for a wide range of taxa, it is rarely tested in snake assemblages. To arrive at robust generalizations about proce­sses and mechanisms structuring island biotas, it is important to examine under-represented taxa such as snakes for the insights they may offer. We tested for the existence of nestedness and underlying causal mechanisms using snake data collected on islands in the Thousand Island Lake, China. We used the line-transect method to survey snake occupancy and abundance on 20 islands during two breeding seasons in 2009 and 2010. We used the recently developed metric WNODF to estimate nestedness. We used Spearman rank correlations to examine the associations of nestedness and habitat variables (area, isolation, and habitat diversity as well as life-history traits (body size, clutch size, geographical range size and area requirement related to species extinction and immigration tendencies. Snake assemblages were significantly nested and were shaped by extinction processes mediated through area effects and habitat nestedness. The nestedness of snake assemblages was not due to passive sampling or selective colonization. From a conservation viewpoint, our results indicate that we should protect both the largest island with the most species-rich community and habitat-rich islands to maximize the number of species preserved [Current Zoology 58 (6: 828–836, 2012].

  16. Reef fish and coral assemblages at Maptaput, Rayong Province

    Directory of Open Access Journals (Sweden)

    Voravit Cheevaporn

    2007-06-01

    Full Text Available This study describes the structure of coral and fish assemblages of a group of small islands and pinnacles in the vicinity of Maptaput deep sea port, Rayong Province, Thailand during 2002. The coral and fish assemblages at Saket Island and nearby pinnacle, Hin-Yai, which are located less than 1 km from the deep sea port, had changed. Living coral cover in 2002 was 8% at Hin-Yai and 4% at Saket Island which decreased from 33% and 64%, respectively in the previous report in 1992. Numbers of coral species at Saket Island decreased from 41 species to 13 species. Acropora spp. that previously dominated the area had nearly disappeared. For fishes, a total of 40 species were found in 2002 the numbers decreased to only 6 species at Saket Island and 36 species at Hin-Yai. Fishes that dominated the area are small pomacentrids. After 1997, the conditions of coral and fish assemblages at Saket Island and Hin-Yai had markedly changed, whereas, the conditions found in the nearby area are much better. Sediment load from port construction was the primary cause of the degradation. This should indicate the adverse effect of sedimentation on coral and reef fish assemblages at Maptaput. Coral communities developed on rock pinnacles west of Maptaput deep-sea port are reported and described herein for the first time.

  17. Sewage pollution impact on Mediterranean rocky-reef fish assemblages.

    Science.gov (United States)

    Azzurro, Ernesto; Matiddi, Marco; Fanelli, Emanuela; Guidetti, Paolo; La Mesa, Gabriele; Scarpato, Alfonso; Axiak, Victor

    2010-06-01

    The effects of sewage outfalls on subtidal fish assemblages were studied along the NW coasts of Malta (Sicily channel, Mediterranean Sea) by means of underwater visual census. The presence of two spatially distinct outfalls discharging untreated wastewaters allowed to use a balanced symmetrical after control/impact (ACI) design that consisted of two putatively impacted locations and two controls, with four sites nested in each location. Surveys were performed in 2006 at two random dates. The study highlighted significant changes at both assemblage and individual species levels. Fish assemblages structures were different between controls and sewages, where total abundance of fish were higher. The responses of individual species to sewage pollution were mostly related to an anomalous increase of two small opportunistic species i.e. Gobius bucchichii and Parablennius rouxi and to a decrease of species of the genus Symphodus, particularly S. roissali and S. ocellatus. Moreover in correspondence of the outfalls, significant changes of the fish size distribution were detected for several species. These results support the use of fish assemblages as biological indicators for marine coastal waters and demonstrated the possibility to obtain sharp signals of environmental impact from some individual fish species. PMID:20193961

  18. Landslide occurrence above the city of Philipsburg, Sint Maarten, Lesser Antilles

    Science.gov (United States)

    Mazabraud, Y.

    2015-12-01

    In the northern part of the Lesser Antilles volcanic arc, the island of Saint Martin/Sint Maartin is a remnant of the Eo-Oligocene "ancient arc". It is constituted of Oligocene granodiorites intruding Eocene tuff deposits and andesitic lava flows. The eastern and western parts of the island are covered with Miocene limestone (Terre-Basses and Tintamarre islet). The igneous rocks outcrop in the central part of the island. As a response to tropical weathering, the coarse grain granodiorites are deeply eroded and form depressions. The very fine-grained tuffs are on the contrary forming crests and hilltops. At Fort Hill, immediately west of Philipsburg city, the metamorphised tuffs are extending North-South, following the direction of the contact with the granodiorite that form the base of the hill. The granodiorite is quartz bearing and its magmatic prismation is well developed. It shows fractures in both directions, parallel and perpendicular to the contact (i.e. north-south and east-west). Being in the hill-slope orientation, the contact parallel fractures are re-activated into normal faults. Several blocks are individualized, sliding downhill towards the first houses. In this work, we present a geological sketch of the Fort Hill landslide and its applications with regard to disaster mitigation. We also present ongoing satellite survey of deformation through time. The aim being to decipher in the signal the average quantity of sliding from the transient, hurricane related part.

  19. Probabilistic hurricane-induced storm surge hazard assessment in Guadeloupe, Lesser Antilles

    Science.gov (United States)

    Krien, Y.; Dudon, B.; Roger, J.; Zahibo, N.

    2015-01-01

    Current storm surge hazard maps in the French West Indies are essentially based on simple statistical methods using limited historical data and early low-resolution models which do not take the effect of waves into account. In this paper, we infer new 100 and 1000 year surge levels in Guadeloupe from the numerical modelling of storm surges induced by a large set of synthetic events that are in statistical agreement with features of historical hurricanes in the North Atlantic Basin between 1980 and 2011. Computations are performed using the wave-current coupled model ADCIRC-SWAN with high grid resolutions (up to 40-60 m) in the coastal and wave dissipation areas. This model is validated against observations during past events such as hurricane HUGO (1989). Results are generally found to be in reasonable agreement with past studies in areas where surge is essentially wind-driven, but to differ significantly in coastal regions where the transfer of momentum from waves to the water column constitutes a non-negligible part of the total surge. The methodology, which can be applied to other islands in the Lesser Antilles, allows to obtain storm surge level maps that can be of major interest for coastal planners and decision makers in terms of risk management.

  20. Genetic Diversity in the Lesser Antilles and Its Implications for the Settlement of the Caribbean Basin.

    Directory of Open Access Journals (Sweden)

    Jada Benn Torres

    Full Text Available Historical discourses about the Caribbean often chronicle West African and European influence to the general neglect of indigenous people's contributions to the contemporary region. Consequently, demographic histories of Caribbean people prior to and after European contact are not well understood. Although archeological evidence suggests that the Lesser Antilles were populated in a series of northward and eastern migratory waves, many questions remain regarding the relationship of the Caribbean migrants to other indigenous people of South and Central America and changes to the demography of indigenous communities post-European contact. To explore these issues, we analyzed mitochondrial DNA and Y-chromosome diversity in 12 unrelated individuals from the First Peoples Community in Arima, Trinidad, and 43 unrelated Garifuna individuals residing in St. Vincent. In this community-sanctioned research, we detected maternal indigenous ancestry in 42% of the participants, with the remainder having haplotypes indicative of African and South Asian maternal ancestry. Analysis of Y-chromosome variation revealed paternal indigenous American ancestry indicated by the presence of haplogroup Q-M3 in 28% of the male participants from both communities, with the remainder possessing either African or European haplogroups. This finding is the first report of indigenous American paternal ancestry among indigenous populations in this region of the Caribbean. Overall, this study illustrates the role of the region's first peoples in shaping the genetic diversity seen in contemporary Caribbean populations.

  1. [Spatial and temporal patterns of stream fish assemblages in the Qiupu Headwaters National Wetland Park].

    Science.gov (United States)

    Wang, Wen-Jian; Chu, Ling; Si, Chun; Zhu, Ren; Chen, Wen-Hao; Chen, Fang-Ming; Yan, Yun-Zhi

    2013-08-01

    Identifying and clarifying how stream fish assemblage patterns vary spatially and temporally are basic measures for the conservation and management of fish species. Based on data collected from 24 wadeable reaches within the Qiupu Headwaters National Wetland Park between May and October 2012, we examined the spatial and temporal patterns of the assemblage structures and diversities, collecting a total of 29 fish species belonging to four orders and ten families. The results of our survey showed influences of local habitat and tributary spatial position variables on fish assemblages. Fish diversity showed significant variations across stream-orders and seasons, which were higher in the second-order streams than in first-order streams and higher in October than in May. Habitat factors such as substrate coarseness and heterogeneity, water temperature and water depth, as well as tributary position factor-link, showed significant effects on fish diversity. Fish assemblages fitted the nested pattern that upstream assemblages presented as a nested subset of downstream assemblages. Fish assemblage structures did not vary significantly across seasons but did across stream-orders; fish assemblages between first- and second-order streams showed significant differences despite some overlap. These spatial differences mainly resulted from spatial variations of the relative abundance of Cobitis rarus, Ctenogobius sp., Zacco platypus, Phoxinus oxycephalus, Rhodeus ocellatus and Vanmanenia stenosoma, among which P. oxycephalus had higher abundance in first-order than in second-order streams but the other five species were more abundant in second-order streams. Fish assemblage structures were significantly related to substrate heterogeneity, water depth, stream order, link and C-link. PMID:23913894

  2. Magnesite-bearing inclusion assemblage in natural diamond

    Science.gov (United States)

    Wang, Alian; Pasteris, Jill D.; Meyer, Henry O. A.; Dele-Duboi, Marie L.

    1996-06-01

    A significant mineral assemblage has been found as an inclusion in a natural diamond from the Finsch kimberlite pipe of South Africa: a euhedral rhombohedron-shaped magnesite (MgCO 3) crystal (d ˜ 30 μm) co-exists with several idiomorphic olivine [(Mg 1.86Fe 0.14)SiO 4] grains (d ˜ 80 μm). Many tiny anatase (TiO 2) particles (d ˜ 2-5 μm) and microcrystallites (d disordered graphite are attached to the surface of the magnesite grain. Structural and compositional characterization of the inclusion phases was achieved by micro-Raman spectroscopy and electron microprobe analysis. The occurrence of this syngenetic multiphase inclusion assemblage in a natural diamond provides unambiguous evidence for the existence in the Earth's mantle of magnesite, which has been proposed as a major carbon reservoir in most of the mantle. Both the formation and preservation aspects of the assemblage have been investigated. The mineralogy of the assemblage indicates that carbonated peridotite formed the surrounding petrologic environment. The inclusion assemblage suggests two reactions involving the decomposition of carbonates in mantle peridotite during decompression, which, in part, may explain the paucity of magnesite that has been found in other mantle rocks. The chemical inertness and low compressibility of the host diamond must have been critical to the preservation of this magnesite-bearing assemblage. The incorporation of a pure TiO 2 phase in a peridotitic diamond inclusion and its occurrence in the anatase structural form further emphasize the unusual conditions that allowed both the formation and preservation of this multiphase inclusion. The P-T-fO 2 conditions defined by the inclusion assemblage are represented by the intersection of the graphite-diamond transition curve and the enstatite-magnesite-olivine-diamond buffer. The oxygen fugacity range represented by the inclusion assemblage is below that of the quartz-fayalite-magnetite and CCOCO 2 buffers in the P

  3. Geographical assemblages of European raptors and owls

    Science.gov (United States)

    López-López, Pascual; Benavent-Corai, José; García-Ripollés, Clara

    2008-09-01

    In this work we look for geographical structure patterns in European raptors (Order: Falconiformes) and owls (Order: Strigiformes). For this purpose we have conducted our research using freely available tools such as statistical software and databases. To perform the study, presence-absence data for the European raptors and owl species (Class Aves) were downloaded from the BirdLife International website. Using the freely available "pvclust" R-package, we applied similarity Jaccard index and cluster analysis in order to delineate biogeographical relationships for European countries. According to the cluster of similarity, we found that Europe is structured into two main geographical assemblages. The larger length branch separated two main groups: one containing Iceland, Greenland and the countries of central, northern and northwestern Europe, and the other group including the countries of eastern, southern and southwestern Europe. Both groups are divided into two main subgroups. According to our results, the European raptors and owls could be considered structured into four meta-communities well delimited by suture zones defined by Remington (1968) [Remington, C.L., 1968. Suture-zones of hybrid interaction between recently joined biotas. Evol. Biol. 2, 321-428]. Climatic oscillations during the Quaternary Ice Ages could explain at least in part the modern geographical distribution of the group.

  4. Snake assemblages of Marajó Island, Pará state, Brazil

    Directory of Open Access Journals (Sweden)

    Gerson Moreira Rodrigues

    2016-01-01

    Full Text Available ABSTRACT We describe the diversity, natural history and structure of snake assemblages from Marajó Island, state of Pará, Brazil, after analyzing 439 specimens deposited in herpetological collections. We tested the hypothesis that snake assemblages from forest and open areas of Marajó Island are distinct with regard to their structure, composition and functional groups. To compare the snake composition of the forest and open areas of Marajó with other comparable assemblages in Brazil, Principal Coordinate Analysis and Clustering tests were performed. A total of 61 species of snakes was recorded for Marajó, with ten species cited for the first time for the study area (Atractus natans Hoogmoed & Prudente, 2003, A. schach (Boie, 1827, Dendrophidion dendrophis (Schlegel, 1837, Helicops hagmanni Roux, 1910, Hydrops martii (Wagler in Spix, 1824, Lygophis meridionalis (Schenkel, 1901, Erythrolamprus typhlus (Linnaeus, 1758, Philodryas argentea (Daudin, 1803, Siphlophis cervinus (Laurenti, 1768, and Thamnodynastes sp.. The composition and structure of snake assemblages between forested and open were different, with five functional groups of snakes in forest areas, and three groups in open areas, based on habit and habitat. In all, 19 species were exclusive to forest areas, 10 were exclusive to open areas and 26 species were recorded in both areas. Our results revealed greater richness for forested areas, probably due to greater habitat heterogeneity. The species composition for forested area in Marajó was similar to that found in other Amazonian assemblages, while that for open areas was more similar to the Pantanal region than other open area assemblages. The general structure of the snake assemblage of Marajó was dominated by anurophagous, terrestrial and diurnal species. Terrestrial, arboreal and semi-arboreal snakes showed a seasonal offspring production pattern, while the pattern for aquatic and semi-aquatic species was aseasonal. The

  5. Spatial and seasonal patterns in fish assemblage in Corrego Rico, upper Parana River basin

    Directory of Open Access Journals (Sweden)

    Erico L. H Takahashi

    2013-03-01

    Full Text Available The upper Paraná River basin drains areas of intensive industry and agriculture, suffering negative impacts. The Córrego Rico flows through sugar cane fields and receives urban wastewater. The aim of this work is to describe and to compare the fish assemblage structure in Córrego Rico. Six standardized bimonthly samples were collected between August 2008 and June 2009 in seven different stretches of Córrego Rico. Fishes were collected with an experimental seine and sieves, euthanized, fixed in formalin and preserved in ethanol for counting and identification. Data were recorded for water parameters, instream habitat and riparian features within each stretch. Non-metric multidimensional scaling, species richness and diversity analysis were performed to examine spatial and seasonal variation in assemblage structure. Fish assemblage structure was correlated with instream habitat and water parameters. The fish assemblage was divided in three groups: upper, middle and lower reaches. High values of richness and diversity were observed in the upper and lower stretches due to connectivity with a small lake and Mogi Guaçu River, respectively. Middle stretches showed low values of richness and diversity suggesting that a small dam in the middle stretch negatively impacts the fish assemblage. Seasonal differences in fish assemblage structure were observed only in the lower stretches.

  6. Terroir is a key driver of seed-associated microbial assemblages.

    Science.gov (United States)

    Klaedtke, Stephanie; Jacques, Marie-Agnès; Raggi, Lorenzo; Préveaux, Anne; Bonneau, Sophie; Negri, Valeria; Chable, Véronique; Barret, Matthieu

    2016-06-01

    Seeds have evolved in association with diverse microbial assemblages that may influence plant growth and health. However, little is known about the composition of seed-associated microbial assemblages and the ecological processes shaping their structures. In this work, we monitored the relative influence of the host genotypes and terroir on the structure of the seed microbiota through metabarcoding analysis of different microbial assemblages associated to five different bean cultivars harvested in two distinct farms. Overall, few bacterial and fungal operational taxonomic units (OTUs) were conserved across all seed samples. The lack of shared OTUs between samples is explained by a significant effect of the farm site on the structure of microbial assemblage, which explained 12.2% and 39.7% of variance in bacterial and fungal diversity across samples. This site-specific effect is reflected by the significant enrichment of 70 OTUs in Brittany and 88 OTUs in Luxembourg that lead to differences in co-occurrence patterns. In contrast, variance in microbial assemblage structure was not explained by host genotype. Altogether, these results suggest that seed-associated microbial assemblage is determined by niche-based processes and that the terroir is a key driver of these selective forces. PMID:26171841

  7. Upper Carboniferous ostracode assemblages from a shale basin and their relationship to depositional environments

    Energy Technology Data Exchange (ETDEWEB)

    Knox, L.W.; King, H.L.

    1985-01-01

    A sequence of more than 800 feet of mostly shale and silty shale of Lower and Middle Pennsylvanian age is exposed about 10 miles northeast of Ardmore, Oklahoma, in the Ardmore Basin. The sequence is considered to represent rather continuous sedimentation in a narrow structural basin located in the northern part of the Southern Oklahoma Aulacogen. Bulk sampling of some 140 feet of shale above a single thin coal within the sequence has yielded two different ostracode assemblages. The assemblage located within 15 feet above the coal is characterized by moderate diversity and relatively great abundance of ostracodes. Dominant genera are Healdia, Bairdia, Pseudobythocypris, Amphissites, Hollinella, and Fabalicypris. Both the stratigraphic position (just above the coal) and comparison with other North American and European ostracode assemblages suggest a marine near-shore transitional to off-shore environment for this assemblage. Above this assemblage occurs a larger stratigraphic interval yielding a lower diversity ostracode assemblage consisting of numerous specimens of Healdia and Pseudobythocypris, as well as fewer numbers of Cavellina, Baridia, and Fabalicypris. This latter assemblage likely represents a marine off-shore environment. Ostracodes are valuable for determination of depositional realms in these shales for at least two reason: (1) macrofossils are virtually absent in the shales and cannot be utilized for paleoecological interpretation; and (2) ostracodes allow discrimination of different depositional realms between shales that are lithologically indistinguishable.

  8. Saproxylic Beetle Assemblage Selection as Determining Factor of Species Distributional Patterns: Implications for Conservation.

    Science.gov (United States)

    García-López, A; Galante, E; Micó, E

    2016-01-01

    The knowledge of the distributional patterns of saproxylic beetles is essential for conservation biology due to the relevance of this fauna in the maintenance of ecological processes and the endangerment of species. The complex community of saproxylic beetles is shaped by different assemblages that are composed of species linked by the microhabitats they use. We evaluate how different the species distribution patterns that are obtained can be, depending on the analyzed assemblage and to what extent these can affect conservation decisions. Beetles were sampled using hollow emergence and window traps in three protected areas of the Iberian Peninsula. Species richness, composition, and diversity turnover were analyzed for each sampling method and showed high variation depending on the analyzed assemblage. Beta diversity was clearly higher among forests for the assemblage captured using window traps. This method collects flying insects from different tree microhabitats and its captures are influenced by the forest structuring. Within forests, the assemblages captured by hollow emergence traps, which collect the fauna linked to tree hollows, showed the largest turnover of species, as they are influenced by the characteristics of each cavity. Moreover, the selection of the forest showing the highest species richness strongly depended on the studied assemblage. This study demonstrates that differences in the studied assemblages (group of species co-occurring in the same habitat) can also lead to significant differences in the identified patterns of species distribution and diversity turnover. This fact will be necessary to take into consideration when making decisions about conservation and management. PMID:27252483

  9. A unique opportunity to reconstruct the volcanic history of the island of Nevis, Lesser Antilles

    Science.gov (United States)

    Saginor, I.; Gazel, E.

    2012-12-01

    We report twelve new ICP-MS analyses and two 40Ar/39Ar ages for the Caribbean island of Nevis, located in the Lesser Antilles. These data show a very strong fractionation trend, suggesting that along strike variations may be primarily controlled by the interaction of rising magma with the upper plate. If this fractionation trend is shown to correlate with age, it may suggest that underplating of the crust is responsible for variations in the makeup of erupted lava over time, particularly with respect to silica content. We have recently been given permission to sample a series of cores being drilled by a geothermal company with the goal of reconstructing the volcanic history of the island. Drilling is often cost-prohibitive, making this a truly unique opportunity. Nevis has received little recent attention from researchers due to the fact that it has not been active for at least 100,000 years and also because of its proximity to the highly active Montserrat, which boasts its very own volcano observatory. However, there are a number of good reasons that make this region and Nevis in particular an ideal location for further analysis. First, and most importantly, is the access to thousands of meters of drill cores that is being provided by a local geothermal company. Second, a robust earthquake catalog exists (Bengoubou-Valerius et al., 2008), so the dip and depth to the subducting slab is well known. These are fundamental parameters that influence the mechanics of a subduction zone, therefore it would be difficult to proceed if they were poorly constrained. Third, prior sampling of Nevis has been limited since Hutton and Nockolds (1978) published the only extensive petrologic study ever performed on the island. This paper contained only 43 geochemical analyses and 6 K-Ar ages, which are less reliable than more modern Ar-Ar ages. Subsequent studies tended to focus on water geochemistry (GeothermEx, 2005), geothermal potential (Geotermica Italiana, 1992; Huttrer, 1998

  10. Ecological niche and species traits: key drivers of regional plant invader assemblages

    OpenAIRE

    Thuiller, Wilfried; Gassó, Núria; Pino, Joan; Vilà, Montserrat

    2012-01-01

    Linking species traits to niche properties is fundamental to understand the spatial structure of invasive species assemblages and the invasion process itself. Using information on 74 invasive species in Spain, the aims of this paper are to (1) test whether invasive plant species assemblages follow a nested pattern at the regional scale, (2) inspect the relationship between range size and niche properties (position and breadth) of invasive species to test whether the nested pattern is a produc...

  11. Spatial Patterns of Ectomycorrhizal Assemblages in a Monospecific Forest in Relation to Host Tree Genotype

    OpenAIRE

    Lang, Christa; Finkeldey, Reiner; Polle, Andrea

    2013-01-01

    Ectomycorrhizas (EcM) are important for soil exploration and thereby may shape belowground interactions of roots. We investigated the composition and spatial structures of EcM assemblages in relation to host genotype in an old-growth, monospecific beech (Fagus sylvatica) forest. We hypothesized that neighboring roots of different beech individuals are colonized by similar EcM assemblages if host genotype had no influence on the fungal colonization and that the similarity would decrease with i...

  12. Contrasting sedimentary processes along a convergent margin: the Lesser Antilles arc system

    Science.gov (United States)

    Picard, Michel; Schneider, Jean-Luc; Boudon, Georges

    2006-12-01

    Sedimentation processes occurring in an active convergent setting are well illustrated in the Lesser Antilles island arc. The margin is related to westward subduction of the North and/or the South America plates beneath the Caribbean plate. From east to west, the arc can be subdivided into several tectono-sedimentary depositional domains: the accretionary prism, the fore-arc basin, the arc platform and inter-arc basin, and the Grenada back-arc basin. The Grenada back-arc basin, the fore-arc basin (Tobago Trough) and the accretionary prism on the east side of the volcanic arc constitute traps for particles derived from the arc platform and the South American continent. The arc is volcanically active, and provides large volumes of volcaniclastic sediments which accumulate mainly in the Grenada basin by volcaniclastic gravity flows (volcanic debris avalanches, debris flows, turbiditic flows) and minor amounts by fallout. By contrast, the eastern side of the margin is fed by ash fallout and minor volcaniclastic turbidites. In this area, the dominant component of the sediments is pelagic in origin, or derived from South America (siliciclastic turbidites). Insular shelves are the locations of carbonate sedimentation, such as large platforms which develop in the Limestone Caribbees in the northern part of the margin. Reworking of carbonate material by turbidity currents also delivers lesser amounts to eastern basins of the margin. This contrasting sedimentation on both sides of the arc platform along the margin is controlled by several interacting factors including basin morphology, volcanic productivity, wind and deep-sea current patterns, and sea-level changes. Basin morphology appears to be the most dominant factor. The western slopes of the arc platform are steeper than the eastern ones, thus favouring gravity flow processes.

  13. Relocalizing a historical earthquake using recent methods: The 10 November 1935 Earthquake near Montserrat, Lesser Antilles

    Science.gov (United States)

    Niemz, P.; Amorèse, D.

    2016-03-01

    This study investigates the hypothesis of Feuillet et al. (2011) that the hypocenter of the seismic event on November 10, 1935 near Montserrat, Lesser Antilles (MS 6 1/4) (Gutenberg and Richter, 1954) was mislocated by other authors and is actually located in the Montserrat-Havers fault zone. While this proposal was based both on a Ground Motion Prediction Equation and on the assumption that earthquakes in this region are bound to prominent fault systems, our study relies on earthquake localization methods using arrival times of the International Seismological Summary (ISS). Results of our methodology suggest that the hypocenter was really located at 16.90° N, 62.53° W. This solution is about 25 km north-west of the location proposed by Feuillet et al. (2011) within the Redonda fault system, northward of the Montserrat-Havers fault zone. As depth phases that contribute valuable insights to the focal depth are not included in the ISS data set and the reassociation of these phases is difficult, the error in depth is high. Taking into account tectonic constraints and the vertical extend of NonLinLoc's uncertainty area of the preferred solution we assume that the focus is most probably in the lower crust between 20 km and the Moho. Our approach shows that the information of the ISS can lead to a reliable solution even without an exhaustive search for seismograms and station bulletins. This is encouraging for a better assessment of seismic and tsunami hazard in the Caribbean, Mexico, South and Central America, where many moderate to large earthquakes occurred in the first half of the 20th century. The limitations during this early phase of seismology which complicate such relocations are described in detail in this study.

  14. Description of extreme-wave deposits on the northern coast of Bonaire, Netherlands Antilles

    Science.gov (United States)

    Watt, Steven G.; Jaffe, Bruce E.; Morton, Robert A.; Richmond, Bruce M.; Gelfencaum, Guy

    2010-01-01

    To develop a better understanding of the origins of extreme-wave deposits and to help assess the potential risk of future overwash events, a field mapping survey was conducted in November 2006 on the northern coast of Bonaire, Netherlands Antilles. Deposits were mapped and analyzed to help develop a systematic sedimentological approach to distinguish the type of extreme-wave event (tsunamis or storms) or combination of events that formed and modified the deposits over time. Extreme-wave deposits on the northern coast of Bonaire between Boka Onima and Boka Olivia have formed sand sheets, poly-modal ridge complexes, and boulder fields on a Pleistocene limestone platform 3?8 meters above sea level. The deposits exhibit characteristics that are consistent with both large storm and tsunami processes that often overlap one another. Sand sheets occur as low-relief features underlying and incorporated with boulder field deposits. The seaward edge of ridge complexes are deposited up to 70 m from the shoreline and can extend over 200 m inland. Over 600 clasts were measured in fields and range in size from coarse gravel to fine block, weigh up to 165 metric tons, and are placed over 280 m from the shoreline. Our analyses indicate that the deposits may have been produced by a combination of hurricane and tsunami events spanning 10s to 1000s of years. Comparing the different deposit morphologies between study sites highlights the importance of shoreline orientation to the distribution of extreme-wave deposits onshore. However, further investigation is required to fully understand the processes that have produced and modified these deposits over time.

  15. Tectonic evolution and mantle structure of the Caribbean

    NARCIS (Netherlands)

    van Benthem, S.; Govers, R.; Spakman, W.; Wortel, R.

    2013-01-01

    We investigate whether predictions of mantle structure from tectonic reconstructions are in agreement with a detailed tomographic image of seismic P wave velocity structure under the Caribbean region. In the upper mantle, positive seismic anomalies are imaged under the Lesser Antilles and Puerto Ric

  16. Three decades of recurrent declines and recoveries in corals belie ongoing change in fish assemblages

    Science.gov (United States)

    Lamy, T.; Galzin, R.; Kulbicki, M.; Lison de Loma, T.; Claudet, J.

    2016-03-01

    Coral reefs are increasingly being altered by a myriad of anthropogenic activities and natural disturbances. Long-term studies offer unique opportunities to understand how multiple and recurrent disturbances can influence coral reef resilience and long-term dynamics. While the long-term dynamics of coral assemblages have been extensively documented, the long-term dynamics of coral reef fish assemblages have received less attention. Here, we describe the changes in fish assemblages on Tiahura reef, Moorea, from 1979 to 2011. During this 33-yr period, Tiahura was exposed to multiple disturbances (crown-of-thorns seastar outbreaks and cyclones) that caused recurrent declines and recoveries of coral cover and changes in the dominant coral genera. These shifts in coral composition were associated with long-term cascading effects on fish assemblages. The composition and trophic structure of fish assemblages continuously shifted without returning to their initial composition, whereas fish species richness remained stable, albeit with a small increase over time. We detected nonlinear responses of fish density when corals were most degraded. When coral cover dropped below 10 % following a severe crown-of-thorns sea star outbreak, the density of most fish trophic groups sharply decreased. Our study shows that historical contingency may potentially be an important but largely underestimated factor explaining the contemporary structure of reef fish assemblages and suggests that temporal stability in their structure and function should not necessarily be the target of management strategies that aim at increasing or maintaining coral reef resilience.

  17. Distribution of polychaete assemblage in relation to natural environmental variation and anthropogenic stress

    Science.gov (United States)

    Zan, Xiaoxiao; Zhang, Chongliang; Xu, Binduo; Xue, Ying; Ren, Yiping

    2015-08-01

    Polychaete are diverse species of the soft-bottom community, and are often used as indicators in environment monitoring programs. However, the effects of anthropogenic activities and natural environmental variation on polychaete assemblage are rarely addressed. The goals of this study are to identify the effects of natural environmental variation and anthropogenic stress on polychaete assemblage, and to explore the relationship between the polychaete assemblage structure and anthropogenic stress without considering the natural environmental variation. Based on the data collected from the surveys conducted in the tidal flat of Jiaozhou Bay, the relationship between polychaete assemblage structure and environmental variables was determined using multivariate statistical methods including hierarchical cluster analysis, multidimensional scaling (MDS) and canonical correspondence analysis (CCA). The results showed that the polychaete assemblage was dominated by two species, Amphictene japonica and Heteromastus filiformis, and could be divided into two subgroups characterized by high and low species abundance. CCA illustrated that the natural environmental variables including water temperature and the distance from coast had primary effects on the polychaete assemblage structure; while stress of contaminants, such as As and Hg, had the secondary influences; and stress from the aquacultured species, mainly Ruditapes philippinarum, had a limited effect. Colinearity between the natural environmental variables and anthropogenic stress variables caused a critical divergence in the interpretation of CCA results, which highlighted the risk of a lack of information in environment assessment. Glycinde gurjanovae, Sternaspis scutata and Eulalia bilineata may serve as the `contamination indicators', which need to be confirmed in future studies.

  18. Aquatic insect assemblages associated with subalpine stream segment types in relict glaciated headwaters

    Science.gov (United States)

    Kubo, Joshua S.; Torgersen, Christian E.; Bolton, Susan M.; Weekes, Anne A.; Gara, Robert I.

    2013-01-01

    1. Aquatic habitats and biotic assemblages in subalpine headwaters are sensitive to climate and human impacts. Understanding biotic responses to such perturbations and the contribution of high-elevation headwaters to riverine biodiversity requires the assessment of assemblage composition among habitat types. We compared aquatic insect assemblages among headwater stream segment types in relict glaciated subalpine basins in Mt. Rainier National Park, Washington, USA. 2. Aquatic insects were collected during summer and autumn in three headwater basins. In each basin, three different stream segment types were sampled: colluvial groundwater sources, alluvial lake inlets, and cascade-bedrock lake outlets. Ward's hierarchical cluster analysis revealed high β diversity in aquatic insect assemblages, and non-metric multidimensional scaling indicated that spatial and temporal patterns in assemblage composition differed among headwater stream segment types. Aquatic insect assemblages showed more fidelity to stream segment types than to individual basins, and the principal environmental variables associated with assemblage structure were temperature and substrate. 3. Indicator species analyses identified specific aquatic insects associated with each stream segment type. Several rare and potentially endemic aquatic insect taxa were present, including the recently described species, Lednia borealis (Baumann and Kondratieff). 4. Our results indicate that aquatic insect assemblages in relict glaciated subalpine headwaters were strongly differentiated among stream segment types. These results illustrate the contribution of headwaters to riverine biodiversity and emphasise the importance of these habitats for monitoring biotic responses to climate change. Monitoring biotic assemblages in high-elevation headwaters is needed to prevent the potential loss of unique and sensitive biota.

  19. Giardia duodenalis genetic assemblages and hosts

    Directory of Open Access Journals (Sweden)

    Heyworth Martin F.

    2016-01-01

    Full Text Available Techniques for sub-classifying morphologically identical Giardia duodenalis trophozoites have included comparisons of the electrophoretic mobility of enzymes and of chromosomes, and sequencing of genes encoding β-giardin, triose phosphate isomerase, the small subunit of ribosomal RNA and glutamate dehydrogenase. To date, G. duodenalis organisms have been sub-classified into eight genetic assemblages (designated A–H. Genotyping of G. duodenalis organisms isolated from various hosts has shown that assemblages A and B infect the largest range of host species, and appear to be the main (or possibly only G. duodenalis assemblages that undeniably infect human subjects. In at least some cases of assemblage A or B infection in wild mammals, there is suggestive evidence that the infection had resulted from environmental contamination by G. duodenalis cysts of human origin.

  20. Giardia duodenalis genetic assemblages and hosts

    Science.gov (United States)

    Heyworth, Martin F.

    2016-01-01

    Techniques for sub-classifying morphologically identical Giardia duodenalis trophozoites have included comparisons of the electrophoretic mobility of enzymes and of chromosomes, and sequencing of genes encoding β-giardin, triose phosphate isomerase, the small subunit of ribosomal RNA and glutamate dehydrogenase. To date, G. duodenalis organisms have been sub-classified into eight genetic assemblages (designated A–H). Genotyping of G. duodenalis organisms isolated from various hosts has shown that assemblages A and B infect the largest range of host species, and appear to be the main (or possibly only) G. duodenalis assemblages that undeniably infect human subjects. In at least some cases of assemblage A or B infection in wild mammals, there is suggestive evidence that the infection had resulted from environmental contamination by G. duodenalis cysts of human origin. PMID:26984116

  1. Fish assemblages in southern California kelp forests.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is a point file of fish assemblages calculated from diver surveys in kelp forests in Southern California. Visual census data was combined for two separate...

  2. Record Of Both Tectonic Related Vertical Motions and Global Sea Level Rise by Marine Terraces along an Active Arc Volcano. Example of Basse-Terre, Lesser Antilles (French West-Indies).

    Science.gov (United States)

    Fabre, M.; Moysan, M.; Graindorge, D.; Jean-Frederic, L.; Philippon, M. M.; Marcaillou, B.; Léticée, J. L.

    2015-12-01

    Volcano-tectonic history of the Caribbean plate provides direct insight onto the dynamic of the North American Plate westward subduction. Basse-Terre Island is a volcanic chain that belongs to the Lesser Antilles active volcanic arc with a southward decreasing age of volcanism from 3 Ma to present day.We investigate records of vertical motion along Basse-Terre through a morphostructural analysis of the Pleistocene-Holocene shallow-water carbonate platforms and associated terraces that surround Basse-Terre Island. This study is based on new high-resolution bathymetric and dense seismic data acquired during the GEOTREF oceanographic survey (2015, February). Our bathymetric and topographic Digital Terrain Model together with the "Litto3D" Lidar data (IGN/SHOM) images the island topography and the platform bathymetry to a depth of 200m with horizontal and vertical resolutions of 5m and ~cm respectively. This detailed study highlights the morphostructure of terraces built during the last transgression in order to identify and quantify their vertical motions. We analyze inherited morphology and structures of the forearc that affect the platform to discuss effects of the regional tectonics context. A particular emphasis is put on the influence of the NW-SE arc parallel transtensive Montserrat-Bouillante fault system onto the platform geometry. At last, the distribution of Basse-Terre terraces is compared with terraces distribution around other Lesser Antilles island and the Bahamas stable margin platform. We aim at discriminating the influence of the Pleistocene global sea-level rise from the one of tectonic vertical deformations.

  3. Unlocking the bacterial and fungal communities assemblages of sugarcane microbiome.

    Science.gov (United States)

    de Souza, Rafael Soares Correa; Okura, Vagner Katsumi; Armanhi, Jaderson Silveira Leite; Jorrín, Beatriz; Lozano, Núria; da Silva, Márcio José; González-Guerrero, Manuel; de Araújo, Laura Migliorini; Verza, Natália Cristina; Bagheri, Homayoun Chaichian; Imperial, Juan; Arruda, Paulo

    2016-01-01

    Plant microbiome and its manipulation herald a new era for plant biotechnology with the potential to benefit sustainable crop production. However, studies evaluating the diversity, structure and impact of the microbiota in economic important crops are still rare. Here we describe a comprehensive inventory of the structure and assemblage of the bacterial and fungal communities associated with sugarcane. Our analysis identified 23,811 bacterial OTUs and an unexpected 11,727 fungal OTUs inhabiting the endophytic and exophytic compartments of roots, shoots, and leaves. These communities originate primarily from native soil around plants and colonize plant organs in distinct patterns. The sample type is the primary driver of fungal community assemblage, and the organ compartment plays a major role in bacterial community assemblage. We identified core bacterial and fungal communities composed of less than 20% of the total microbial richness but accounting for over 90% of the total microbial relative abundance. The roots showed 89 core bacterial families, 19 of which accounted for 44% of the total relative abundance. Stalks are dominated by groups of yeasts that represent over 12% of total relative abundance. The core microbiome described here comprise groups whose biological role underlies important traits in plant growth and fermentative processes. PMID:27358031

  4. Unlocking the bacterial and fungal communities assemblages of sugarcane microbiome

    Science.gov (United States)

    de Souza, Rafael Soares Correa; Okura, Vagner Katsumi; Armanhi, Jaderson Silveira Leite; Jorrín, Beatriz; Lozano, Núria; da Silva, Márcio José; González-Guerrero, Manuel; de Araújo, Laura Migliorini; Verza, Natália Cristina; Bagheri, Homayoun Chaichian; Imperial, Juan; Arruda, Paulo

    2016-01-01

    Plant microbiome and its manipulation herald a new era for plant biotechnology with the potential to benefit sustainable crop production. However, studies evaluating the diversity, structure and impact of the microbiota in economic important crops are still rare. Here we describe a comprehensive inventory of the structure and assemblage of the bacterial and fungal communities associated with sugarcane. Our analysis identified 23,811 bacterial OTUs and an unexpected 11,727 fungal OTUs inhabiting the endophytic and exophytic compartments of roots, shoots, and leaves. These communities originate primarily from native soil around plants and colonize plant organs in distinct patterns. The sample type is the primary driver of fungal community assemblage, and the organ compartment plays a major role in bacterial community assemblage. We identified core bacterial and fungal communities composed of less than 20% of the total microbial richness but accounting for over 90% of the total microbial relative abundance. The roots showed 89 core bacterial families, 19 of which accounted for 44% of the total relative abundance. Stalks are dominated by groups of yeasts that represent over 12% of total relative abundance. The core microbiome described here comprise groups whose biological role underlies important traits in plant growth and fermentative processes. PMID:27358031

  5. Apparatuses, Globalities, Assemblages: Third Cinema, Now

    OpenAIRE

    Benfield, Dalida Maria

    2011-01-01

    AbstractApparatuses, Globalities, Assemblages:Third Cinema, NowbyDalida Maria BenfieldDoctor of Philosophy in Ethnic Studiesand the Designated Emphasis in Women, Gender and SexualityUniversity of California, BerkeleyProfessor Trinh T. Minh-ha, ChairColonial wounds endure but are refigured in 21st century cinematic landscapes. These are spaces of memory and mourning, as well as sites of creativity and transformation. New assemblages of power emerge along with equally complex amalgams of resist...

  6. Territorial assemblages simulation for territorial intelligence

    OpenAIRE

    Soulier, Eddie; Neffati, Houda; Legrand, Jacky; Rousseau, Francis; Bugeaud, Florie; Calvez, Philippe; Saurel, Pierre

    2011-01-01

    The following article is based on the theory of assemblage ontology seen as a framework to formalize new projects territories in a perspective of territorial intelligence. The area of research is PARIS-SACLAY Campus, which views the development of a world science cluster. The assemblages are simulating by means of simplicial complexes. Its objective is to offer new decision-making tools to territorial community.

  7. Seismic tomography of Basse-Terre volcanic island, Guadeloupe, Lesser Antilles, using earthquake travel times and noise correlations

    Science.gov (United States)

    Barnoud, Anne; Coutant, Olivier; Bouligand, Claire; Massin, Frédérick; Stehly, Laurent

    2015-04-01

    We image the volcanic island of Basse-Terre, Guadeloupe, Lesser Antilles, using both earthquake travel times and noise correlations. (1) A new earthquake catalog was recently compiled for the Lesser Antilles by the CDSA/OVSG/IPGP (Massin et al., EGU General Assembly 2014) and allows us to perform classical travel time tomography to obtain smooth 3D body wave velocity models. The geometrical configuration of the volcanic arc controls the resolution of the model in our zone of interest. (2) Surface wave tomography using noise correlations was successfully applied to volcanoes (Brenguier et al., Geophys. Res. Lett. 2007). We use seismic noise recorded at 16 broad-band stations and 9 short-period stations from Basse-Terre over a period of six years (2007-2012). For each station pair, we extract a dispersion curve from the noise correlation to get surface wave velocity models. The inversion of the dispersion curves produces a 3D S-wave velocity model of the island. The spatial distribution of seismic stations accross the island is highly heterogeneous, leading to higher resolution near the dome of the Soufrière of Guadeloupe volcano. Resulting velocity models are compared with densities obtained by 3D inversion of gravimetric data (Barnoud et al., AGU Fall Meeting 2013). Further work should include simultaneous inversion of seismic and gravimetric datasets to overcome resolution limitations.

  8. Inter-annual rainfall variability in the eastern Antilles and coupling with the regional and intra-seasonal circulation

    Science.gov (United States)

    Jury, Mark R.

    2015-08-01

    Climate variability in the eastern Antilles island chain is analyzed via principal component analysis of high-resolution monthly rainfall in the period 1981-2013. The second mode reflecting higher rainfall in July-October season between Martinique and Grenada is the focus of this study. Higher rainfall corresponds with a weakened trade wind and boundary current along the southern edge of the Caribbean. This quells the coastal upwelling off Venezuela and builds the freshwater plume east of Trinidad. There is corresponding upper easterly wind flow that intensifies passing tropical waves. During a storm event over the Antilles on 4-5 October 2010, there was inflow from east of Guyana where low salinity and high sea temperatures enable surplus latent heat fluxes. A N-S convective rain band forms ˜500 km east of the cyclonic vortex. Many features at the weather timescale reflect the seasonal correlation and composite difference maps and El Nino Southern Oscillation (ENSO) modulation of oceanic inter-basin transfers.

  9. Amsterdam Expeditions to the West Indian Islands, Report 21. A sipunculan, reported to be “interstitial” from the Netherlands Antilles

    NARCIS (Netherlands)

    Edmonds, S.J.

    1982-01-01

    The sipunculan Aspidosiphon exiguus Edmonds, 1974, is recorded from Bonaire and Curaçao (Netherlands Antilles). It was first described from three localities in Cuba. Unlike most aspidosiphonids, the species seems to belong to the interstitial fauna of marine beaches and appears to be tolerant of con

  10. Altered vegetative assemblage trajectories within an urban brownfield

    International Nuclear Information System (INIS)

    Recognizing the growing importance of both structure (maintenance of biodiversity) and function (fostering natural cycles) of urban ecologies, we examine coarse scale (herbaceous, shrub and forest) beta guild trajectory in an urban brownfield. The distribution of the pioneer forest assemblage dominated by Betula populifolia Marsh. and Populus spp. could be correlated positively with total soil metal load (arsenic, cadmium, chromium, copper, lead, zinc, lead and vanadium),whereas herbaceous and shrub guilds were negatively correlated. Distinct assemblage development trajectories above and below a critical soil metal threshold are demonstrated. In addition, we postulate that the translocation of metals into the plant tissue of several dominant species may provide a positive feedback loop, maintaining relatively high concentrations of metals in the litter and soil. Therefore assembly theory, which allows for the development of alternate stable states, may provide a better model for the establishment of restoration objectives on degraded urban sites. - Highlights: → Forest distribution and total soil metal load yield strong positive correlations. → Shrub and herbaceous guild distribution and TML are negative and weaker. → Below a critical TML threshold transition between guilds exhibit a standard trajectory. → Above the critical TML threshold the shrub guild is virtually absent. → Metal cycling has the potential to lead to an alternative steady state. - High concentrationsof soil metals, impact the trajectory of vegetative assemblages in an urban brownfield leading to the speculation of an alternate stable state.

  11. Temporal variation in fish assemblage composition on a tidal flat

    Directory of Open Access Journals (Sweden)

    Henry L. Spach

    2004-03-01

    Full Text Available Annual variation in the fish assemblage characteristics on a tidal flat was studied in coastal Paraná, in southern Brazil. Fish were collected between August 1998 and July 1999, during the diurnal high tide and diurnal and nocturnal low tide of the syzygial (full moon and quadrature (waning moon tides, to characterize temporal change in assemblage composition. A total of 64,265 fish in 133 species were collected. The average number of species and individuals, biomass, species richness, diversity (mass and equitability varied significantly over time . The dissimilarity of the assemblage was greatest in August, September and October in contrast with the period from November to January, with the lowest dissimilarity. The combined action of water temperature, salinity and wind intensity had a great influence over the structure of the fish assemblage.Os peixes de uma planície de maré da praia Balneário de Pontal do Sul, Paraná, foram coletados, na preamar diurna e na baixa-mar diurna e noturna das marés de sizígia e de quadratura, visando caracterizar as mudanças temporais entre agosto de 1998 e julho de 1999. As coletas totalizaram 64.265 peixes de 133 espécies. Foram observadas diferenças significativas na captura média em número de espécies e de peixes, peso total e nos índices de riqueza, diversidade (H' peso e eqüitatividade entre os meses de coleta. A dissimilaridade da ictiofauna foi maior entre os meses de agosto, setembro e outubro em comparação com o período de novembro a janeiro. A ação combinada da temperatura da água, salinidade e intensidade do vento, influenciaram mais sobre a estrutura da assembléia de peixes.

  12. Mercury concentration, speciation and budget in volcanic aquifers: Italy and Guadeloupe (Lesser Antilles)

    Science.gov (United States)

    Bagnato, E.; Aiuppa, A.; Parello, F.; D'Alessandro, W.; Allard, P.; Calabrese, S.

    2009-01-01

    Quantifying the contribution of volcanism to global mercury (Hg) emissions is important to understand the pathways and the mechanisms of Hg cycling through the Earth's geochemical reservoirs and to assess its environmental impacts. While previous studies have suggested that degassing volcanoes might contribute importantly to the atmospheric budget of mercury, little is known about the amount and behaviour of Hg in volcanic aquifers. Here we report on detailed investigations of both the content and the speciation of mercury in aquifers of active volcanoes in Italy and Guadeloupe Island (Lesser Antilles). In the studied groundwaters, total Hg (THg) concentrations range from 10 to 500 ng/l and are lower than the 1000 ng/l threshold value for human health protection fixed by the World Health Organization [WHO (1993): WHO Guidelines for Drinking Water Quality- http://www.who.int/water_sanitation_health/GDWQ/index.htlm]. Positive co-variations of (THg) with sulphate indicate that Hg-SO 4-rich acid groundwaters receive a direct input of magmatic/hydrothermal gases carrying mercury as Hg 0(gas). Increasing THg in a volcanic aquifer could thus be a sensitive tracer of magmatic gas input prior to an eruption. Since the complex behaviour and toxicity of mercury in waters depend on its chemical speciation, we carefully determined the different aqueous forms of this element in our samples. We find that dissolved elemental Hg 0(aq) and particulate-bound Hg (Hg P) widely prevail in volcanic aquifers, in proportions that highlight the efficiency of Hg adsorption onto colloidal particles. Moreover, we observe that dissolved Hg 0aq and Hg(II) forms coexist in comparable amount in most of the waters, in stark contrast to the results of thermodynamic equilibrium modelling. Therefore, chemical equilibrium between dissolved mercury species in volcanic waters is either prevented by natural kinetic effects or not preserved in collected waters due to sampling/storage artefacts. Finally, we

  13. Fractures, Faults, and Hydrothermal Systems of Puna, Hawaii, and Montserrat, Lesser Antilles

    Science.gov (United States)

    Kenedi, Catherine Lewis

    The focus of this work is to use geologic and geophysical methods to better understand the faults and fracture systems at Puna, in southeastern Hawaii, and southern Montserrat, in the Lesser Antilles. The particular interest is understanding and locating the deep fracture networks that are necessary for fluid circulation in hydrothermal systems. The dissertation first presents a study in which identification of large scale faulting places Montserrat into a tectonic context. Then follow studies of Puna and Montserrat that focus on faults and fractures of the deep hydrothermal systems. The first chapter consists of the results of the SEA-CALIPSO experiment seismic reflection data, recorded on a 48 channel streamer with the active source as a 2600 in3 airgun. This chapter discusses volcaniclastic debris fans off the east coast of Montserrat and faults off the west coast. The work places Montserrat in a transtensional environment (influenced by oblique subduction) as well as in a complex local stress regime. One conclusion is that the stress regime is inconsistent with the larger arc due to the influence of local magmatism and stress. The second chapter is a seismic study of the Puna hydrothermal system (PHS) along the Kilauea Lower East Rift Zone. The PHS occurs at a left step in the rift, where a fracture network has been formed between fault segments. It is a productive geothermal field, extracting steam and reinjecting cooled, condensed fluids. A network of eight borehole seismometers recorded >6000 earthquakes. Most of the earthquakes are very small (Puna the transfer zone is a relay ramp. The results from the PHS are used as an example to examine the proposed hydrothermal system at St. George's Hill, Montserrat. In southern Montserrat, hot springs and fumaroles suggest a deep hydrothermal system heated by local magmatism. A magnetotelluric study obtained resistivity data that suggest focused alteration under southeastern Montserrat that is likely to be along

  14. Genetic Evidence of Hybridization between the Endangered Native Species Iguana delicatissima and the Invasive Iguana iguana (Reptilia, Iguanidae in the Lesser Antilles: Management Implications.

    Directory of Open Access Journals (Sweden)

    Barbara Vuillaume

    Full Text Available The worldwide increase of hybridization in different groups is thought to have become more important with the loss of isolating barriers and the introduction of invasive species. This phenomenon could result in the extinction of endemic species. This study aims at investigating the hybridization dynamics between the endemic and threatened Lesser Antillean iguana (Iguana delicatissima and the invasive common green iguana (Iguana iguana in the Lesser Antilles, as well as assessing the impact of interspecific hybridization on the decline of I. delicatissima. 59 I. delicatissima (5 localities, 47 I. iguana (12 localities and 27 hybrids (5 localities, who were all identified based on morphological characters, have been genotyped at 15 microsatellites markers. We also sequenced hybrids using ND4 mitochondrial loci to further investigate mitochondrial introgression. The genetic clustering of species and hybrid genetic assignment were performed using a comparative approach, through the implementation of a Discriminant Analysis of Principal Component (DAPC based on statistics, as well as genetic clustering approaches based on the genetic models of several populations (Structure, NewHybrids and HIest, in order to get full characterization of hybridization patterns and introgression dynamics across the islands. The iguanas identified as hybrids in the wild, thanks to morphological analysis, were all genetically F1, F2, or backcrosses. A high proportion of individuals were also the result of a longer-term admixture. The absence of reproductive barriers between species leads to hybridization when species are in contact. Yet morphological and behavioral differences between species could explain why males I. iguana may dominate I. delicatissima, thus resulting in short-term species displacement and extinction by hybridization and recurrent introgression from I. iguana toward I. delicatissima. As a consequence, I. delicatissima gets eliminated through

  15. Genetic Evidence of Hybridization between the Endangered Native Species Iguana delicatissima and the Invasive Iguana iguana (Reptilia, Iguanidae) in the Lesser Antilles: Management Implications.

    Science.gov (United States)

    Vuillaume, Barbara; Valette, Victorien; Lepais, Olivier; Grandjean, Frédéric; Breuil, Michel

    2015-01-01

    The worldwide increase of hybridization in different groups is thought to have become more important with the loss of isolating barriers and the introduction of invasive species. This phenomenon could result in the extinction of endemic species. This study aims at investigating the hybridization dynamics between the endemic and threatened Lesser Antillean iguana (Iguana delicatissima) and the invasive common green iguana (Iguana iguana) in the Lesser Antilles, as well as assessing the impact of interspecific hybridization on the decline of I. delicatissima. 59 I. delicatissima (5 localities), 47 I. iguana (12 localities) and 27 hybrids (5 localities), who were all identified based on morphological characters, have been genotyped at 15 microsatellites markers. We also sequenced hybrids using ND4 mitochondrial loci to further investigate mitochondrial introgression. The genetic clustering of species and hybrid genetic assignment were performed using a comparative approach, through the implementation of a Discriminant Analysis of Principal Component (DAPC) based on statistics, as well as genetic clustering approaches based on the genetic models of several populations (Structure, NewHybrids and HIest), in order to get full characterization of hybridization patterns and introgression dynamics across the islands. The iguanas identified as hybrids in the wild, thanks to morphological analysis, were all genetically F1, F2, or backcrosses. A high proportion of individuals were also the result of a longer-term admixture. The absence of reproductive barriers between species leads to hybridization when species are in contact. Yet morphological and behavioral differences between species could explain why males I. iguana may dominate I. delicatissima, thus resulting in short-term species displacement and extinction by hybridization and recurrent introgression from I. iguana toward I. delicatissima. As a consequence, I. delicatissima gets eliminated through introgression, as

  16. Spatial and temporal variation of fish assemblages in a subtropical small stream of the Huangshan Mountain

    Directory of Open Access Journals (Sweden)

    Yunzhi YAN,Shan HE, Ling CHU, Xiuying XIANG, Yanju JIA, Juan TAO, Yifeng CHEN

    2010-12-01

    Full Text Available Spatial and temporal variation of fish assemblages were investigated seasonally from May 2007 to February 2008 across 11 study sites in a subtropical small stream, the Puxi Stream, of the Huangshan Mountain. Along the longitudinal gradient from headwater to downstream, fish species richness and abundance increased gradually, but then decreased significantly at the lower reaches. The highest species richness and abundance were observed in August and the lowest in February. Based on analysis of similarities (ANOSIM, fish assemblages were significantly different in spatial variation but not in temporal variation. Although differences were observed both among sites and among stream orders, the lower R value in order-variation suggested stream order was not the optimal factor explaining the spatial variation of fish assemblages. In addition, dam construction did not significantly alter fish assemblages in the sites adjacent to and immediately downstream to dams. Using cluster analysis and non-metric Multi Dimensional Scaling analysis (NMS, assemblages were separated into three groups at a Bray-Curtis similarity value of 42%: the upper, middle and lower groups. Following analysis of similarity percentages of species contributions (SIMPER, shifts in occurrence or abundance of S. curriculus, Z. platypus, R. bitterling and A. fasciatus contributed most to the differences amongst the three groups. Standard Deviation Redundancy Analysis (RDA suggested that habitat structure (such as elevation, substrate, and flow velocity contributed to the spatial and temporal pattern of fish assemblages in the Puxi Stream. In conclusion, the fish assemblages in Puxi Stream presented significant spatial but not temporal variation. Human disturbance has perhaps induced the decrease in species diversity in the lower reaches. However, no significant change was observed for fish assemblages in sites far from and immediately downstream from low-head dams [Current Zoology 56 (6

  17. A Comparative Study of Fish Assemblages Near Aquaculture, Artificial and Natural Habitats

    Institute of Scientific and Technical Information of China (English)

    WANG Zhenhua; CHEN Yong; ZHANG Shouyu; WANG Kai; ZHAO Jing; XU Qiang

    2015-01-01

    Habitat plays a critical role in regulating fish community structure. Using the data collected from a monthly trammel net survey in Ma’an archipelago off the east coast of China, we evaluated impacts of five different habitats (artificial reefs, mussel farms, cage aquaculture, rocky reefs and soft bottom) on fish assemblages. This study suggests that artificial reefs (AR) have significantly higher species richness, abundance and diversity than mussel farms (MF) or soft bottom (SB) habitats during most seasons, and that fish taxa in the AR habitats are similar to those in the rocky reef (RR) habitats. Two different fish assemblage patterns were revealed in the study area using non-metric multidimensional scaling ordination: an assemblage dominated by reef fishes (especially by Scor-paenidae species) in AR, RR and cage aquaculture (CA) habitats and an assemblage dominated by Sciaenidae species in MF and SB habitats. We suggest that reef fishes play a key role in differentiating fish community structures in the study area. Although few dif-ferences in fish abundance and diversity were found between the CA and SB habitats, a more diverse age structure was observed in the CA habitats. A much more complex fish assemblage and enhanced population of local species were established as a result of the presence of both floating and fixed artificial structures, probably through improved survival rates.

  18. Oceanographic data collected during the Bonaire 2008: Exploring Coral Reef Sustainability with New Technologies (bonaire2008) on Fetch1 AUV and Gavia AUV's in Netherlands, Antilles from January 6, 2008 - January 29, 2008 (NODC Accession 0072312)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bonaire, Netherlands Antilles, is arguably the most pristine coral reef environment in the Caribbean. The percent coral cover is the highest and percent algal cover...

  19. Fish assemblage dynamics in a Neotropical floodplain relative to aquatic macrophytes and the homogenizing effect of a flood pulse

    Science.gov (United States)

    Gomes, L.C.; Bulla, C. K.; Agostinho, A. A.; Vasconcelos, L. P.; Miranda, Leandro E.

    2012-01-01

    The presence of aquatic macrophytes is a key factor in the selection of habitats by fish in floodplain lakes because these plants enhance the physical and biological complexities of aquatic habitats. The seasonal flood pulse may influence this interaction, but there is no information in the literature about the effects that flood events may have on macrophytes assemblages and its associated effects on fish assemblages. Thus, this article aimed to investigate whether species richness, evenness and similarities in fish assemblage composition differed between littoral areas vegetated with macrophytes and unvegetated areas, before and after a flood. We sampled three lakes in the floodplain of the upper Paraná River basin. Sampling was conducted before (December 2004 and January 2005) and after (early March, late March and May 2005) a flood event. Overall, species richness and evenness were higher in macrophytes-covered areas. Before the flood, the composition of fish assemblages was distinct when comparing vegetated and unvegetated areas. After the flood, the similarity in fish assemblage composition was higher, indicating a homogenization effect of floods for fish inhabiting littoral areas of floodplain lakes. After the flood, opportunistic species dominated the fish assemblages in aquatic macrophytes, apparently restructuring assemblages in the littoral, restarting a succession process. Thus, the observed homogenization effect of the flood could minimize biological interactions and could induce fish assemblages to begin a new process of structurization.

  20. Contrasting the species abundance, species density and diversity of seaweed assemblages in alternative states: Urchin density as a driver of biotic homogenization

    Science.gov (United States)

    Sangil, Carlos; Sansón, Marta; Clemente, Sabrina; Afonso-Carrillo, Julio; Hernández, José Carlos

    2014-01-01

    Differences in seaweed assemblages' structure (species abundance, species density and diversity) were examined in two habitats, urchin barrens and upright seaweed beds on the Canarian Archipelago (eastern Atlantic Ocean) to demonstrate the key role of extreme density of the sea urchin Diadema africana in the homogenization of assemblages in shallow rocky reefs. Univariate and multivariate analyses were used to test for differences in seaweed the assemblages at multiple spatial scales, from sites (< 10 km apart) to islands (25-450 km apart), based on samples collected from six islands. Distance-based linear model routine (DistLM) and distance-based redundancy analysis (dbRDA) were also applied to analyze and model relationships between seaweed assemblages and environmental variables in each habitat. The patterns of spatial variation in assemblage structure were different in urchin barrens compared to upright seaweed beds. In urchin barrens, spatial variation of seaweed assemblages differed between sites only, whereas in upright seaweed beds were observed differences between sites and islands. Sea urchin density and substrate roughness were the two factors determining assemblage structure in urchin barrens. In contrast, in upright seaweed beds, the major factors influencing assemblages were wave exposure, temperature and productivity. We conclude that potential biogeographic patterns of assemblage structure induced by oceanographic conditions were observed only in pristine areas with low urchin density.

  1. Seasonal and diel changes in the structure of a crustacean decapod assemblage associated to a shallow Cymodocea nodosa meadow in northern Tunisia (Mediterranean Sea. An overview of the Mediterranean decapod taxocoenoses.

    Directory of Open Access Journals (Sweden)

    A. DAOULATI

    2013-12-01

    Full Text Available A study on the decapod assemblage inhabiting a shallow meadow of Cymodocea nodosa from the bay of La Goulette (Tunisia was carried from February 2009 to February 2010. Monthly samples (with replicates were taken in the morning and at night, with a small Agassiz trawl. In total 11699 specimens belonging to 41 species were caught. Significant day-night and seasonal changes are mainly related to movements (feeding and recruitments. Higher abundance and richness were reported at night. Analyses rendered no significant relationships between the plant phenology and abundances and richness; neither between the total abundance and temperature, but significant correlations with a time lag of 3 - 4 months between these factors exist, which could be related with hatching and larval development period. The nocturnal and diurnal values in the diversity and equitability indexes are quite similar along the year (peaks in spring - early summer, minimum in autumn - early winter. This pattern is mainly due to the strong dominance of a few species, with maximum abundances during their recruitment events, whose seasonal and day-night changes have been determined. Besides, an overview of the decapods assemblage associated to this seagrass for the Mediterranean Sea has been carried out. The species can be divided into two groups (linked to the leaves and to the sediment. The differences in species composition between areas must be related to different sampling methodologies, feeding and reproductive strategies, but also to the layout and influence of the surrounding habitats.

  2. Role of macrophyte life forms in driving periphytic microalgal assemblages in a Brazilian reservoir

    Directory of Open Access Journals (Sweden)

    Ubirajara L. Fernandes

    2015-08-01

    Full Text Available Macrophytes play several roles in aquatic ecosystems, including the provision of habitat for many aquatic organisms, especially the periphyton. The aims of this study were to characterize the structure of periphytic microalgal assemblages on different aquatic macrophyte life forms in order to establish similarities between assemblages from nearby sampling sites. We hypothesized that i aquatic macrophytes with different life forms and morphological characteristics could differently influence the structure of the periphyton and that ii the greatest similarity in periphyton composition should be observed among macrophytes that occupy the same sampling site. The study was conducted from 2006 to 2008 in the Thomaz Osterne de Alencar reservoir (Crato City, Ceará State, Brazil and involved the taxonomic surveying of microalgae attached to five different macrophytes with the application of structural descriptors (richness, abundance, frequency, diversity and equitability. A total of 127 taxa, of which 44% belonged to the Chlorophyta, were identified. The microalgae assemblages showed high species richness on Salvinia auriculata Aubl., a free-floating macrophyte, and large abundance on Apalanthe granatensis (Humb. & Bonpl. Planch., a submerged anchored macrophyte. ANOVA indicated that periphyton significantly varied among the macrophytes investigated, and nearby sampling sites showed no structural similarities in microalgal assemblages. In general, we can conclude that the structure of periphyton assemblages is influenced by the substrate (i.e., macrophyte organ, as this can not only promote high diversity and equitability but can also be a predictor of dissimilarity in the distribution and frequency of occurrence of microalgae. These results reinforce the findings of other studies that have shown that macrophytes play an important role in structuring the periphyton assemblages.

  3. The Miocene carnivore assemblage of Greece

    Directory of Open Access Journals (Sweden)

    Koufos, G. D.

    2011-12-01

    Full Text Available The Miocene carnivore assemblage of Greece includes a great number of taxa, described in numerous articles since the first decades of the 19th Century. The present article is a revision of all these taxa, providing information about their history, localities, age, as well as their stratigraphic distribution and palaeoenvironment. The Early/Middle Miocene carnivore record of Greece is poor as the available fossiliferous sites and material are rare. However, the Late Miocene one is quite rich, including numerous taxa. The Miocene localities with carnivores and their age are given in a stratigraphic table covering the European Mammal zones from MN 4 to MN 13. The type locality, holotype, and some historical and morphological remarks are given for each taxon. Several carnivore taxa were erected from Greek material and new photos of their holotypes are given. The stratigraphic distribution of the Greek carnivore taxa indicates that they are covering the time span from ~19.0-5.3Ma. The majority of the Miocene taxa (Adcrocuta, Hyaenictitherium, Plioviverrops, Protictitherium, Ictitherium, Indarctos, Dinocrocuta, Promephitis disappeared at the end of Miocene. The composition of the Early/Middle Miocene carnivore assemblage of Greece includes mainly viverrids (Lophocyon, Euboictis, while the hyaenids, percrocutids, felids and mustelids are very few. On the contrary the Late Miocene assemblage is richer, including more subfamilies and species; the hyaenids and mustelids dominate, while the viverrids are absent. The Late Miocene carnivore guild structure is similar to that of the modern Serengeti, indicating a relatively open, savannah-like environment.

    La asociación de carnívoros miocenos de Grecia incluye un gran número de taxones, descritos en numerosos artículos desde las primeras décadas del siglo XIX. El presente artículo supone un esfuerzo de síntesis de todos estos taxones, suministrando información sobre su

  4. Patterns of benthic assemblages invaded and non-invaded by Grateloupia turuturu across rocky intertidal habitats

    Science.gov (United States)

    Freitas, Cristiano; Araújo, Rita; Bertocci, Iacopo

    2016-09-01

    Intertidal benthic assemblages invaded and non-invaded by the introduced Asian red alga Grateloupia turuturu were compared at a rocky shore along the NW coast of Portugal. The structure of whole assemblages, the total richness of taxa and the abundance of individual taxa were examined as response variables in two different habitats (rock pools and emergent rock), two shore levels (low and mid intertidal) and two dates of sampling (June 2013 and June 2014). Invaded and non-invaded assemblages differed consistently across habitats and shore levels. Such differences were driven by 13 (with the green alga genus Ulva, the red alga Chondrus crispus and the mussel Mytilus galloprovincialis driving the total dissimilarity) out of the total 37 taxa identified. Individual taxa revealed idiosyncratic patterns, in several cases (C. crispus, M. galloprovincialis, articulated coralline algae of the genus Corallina and the crustose sporophyte of the red alga Mastocarpus stellatus) there were differences in the abundance of a taxon between invaded and non-invaded assemblages varying with levels of some other experimental factors. The total number of taxa was higher in invaded compared to non-invaded assemblages for each combination of habitat and shore level. Patterns of invasion by G. turuturu along the Portuguese continental coast were recently described in terms of its temporal and spatial distribution, but never examined in terms of differences between invaded and non-invaded assemblages. Such information is very limited for other geographic areas where this species is recorded out of its native range of distribution. Therefore, the present study provides a new contribution to the understanding of modifications of native assemblages associated with the invasion of G. turuturu, opening avenues of research aimed at specifically examining the factors and processes likely responsible for the invasion dynamics and success of this species.

  5. Ectomycorrhizal fungal communities of Coccoloba uvifera (L.) L. mature trees and seedlings in the neotropical coastal forests of Guadeloupe (Lesser Antilles)

    OpenAIRE

    Séne, S.; Avril, R.; Chaintreuil, Clémence; Geoffroy, A; Ndiaye, C; Diedhiou, A. G.; Sadio, O.; Courtecuisse, R.; Sylla, S.; Selosse, M.A.; Bâ, Amadou

    2015-01-01

    We studied belowground and aboveground diversity and distribution of ectomycorrhizal (EM) fungal species colonizing Coccoloba uvifera (L.) L. (seagrape) mature trees and seedlings naturally regenerating in four littoral forests of the Guadeloupe island (Lesser Antilles). We collected 546 sporocarps, 49 sclerotia, and morphotyped 26,722 root tips from mature trees and seedlings. Seven EM fungal species only were recovered among sporocarps (Cantharellus cinnabarinus, Amanita arenicola, Russula ...

  6. Genetic evidence of hybridization between the endangered native species Iguana delicatissima and the invasive Iguana iguana (Reptilia, Iguanidae) in the Lesser Antilles: management Implications

    OpenAIRE

    Vuillaume, Barbara; Valette, Victorien; Lepais, Olivier; Grandjean, Frederic; Breuil, Michel

    2015-01-01

    The worldwide increase of hybridization in different groups is thought to have become more important with the loss of isolating barriers and the introduction of invasive species. This phenomenon could result in the extinction of endemic species. This study aims at investigating the hybridization dynamics between the endemic and threatened Lesser Antillean iguana (Iguana delicatissima) and the invasive common green iguana (Iguana iguana) in the Lesser Antilles, as well as assessing the impact ...

  7. 3-D magnetotelluric inversion with coast effect modeling to assess the geothermal potential of Anses d'Arlet (Martinique, Lesser Antilles)

    OpenAIRE

    Coppo, Nicolas; Hautot, Sophie; Wawrzyniak, Pierre; Baltassat, Jean-Michel; Girard, Jean-François; Tarits, Pascal; Martelet, Guillaume

    2014-01-01

    Within the framework of a global French program towards development of renewable energies, Martinique Island (Lesser Antilles, France) has been extensively investigated (from 2012 to 2013) through an integrated multi-disciplinary approach, with the aim to identify precisely the potential geothermal resources previously highlighted (Gadalia et al., 2014). Among the investigation methods deployed (geological, geochemical and hydrogeological), we carried out three magnetotelluric (MT) surve ys a...

  8. Ecoturisme, conservació de la natura i desenvolupament local: el cas de Mèxic, Amèrica Central i les Grans Antilles.

    OpenAIRE

    Nel·lo Andreu, Marta Gemma

    2003-01-01

    Ecotourism, preservation of nature and local development: the case of Mexico, Central America and the Great AntillesAREA OF STUDY AND METHODOLOGYThe present thesis is a continuity of the dissertation, in which the area of study at the time was limited to Costa Rica, a country that was starting to stand out in 1994 as regards ecotourism. However, in this doctoral thesis the territorial area of analysis has been considered appropriate for extension. The reasons why are exposed below.Throughout ...

  9. Spatial and seasonal variations in the trophic spectrum of demersal fish assemblages in Jiaozhou Bay, China

    Science.gov (United States)

    Han, Dongyan; Xue, Ying; Ren, Yiping; Ma, Qiuyun

    2015-07-01

    Trophic structure of fish communities is fundamental for ecosystem-based fisheries management, and trophic spectrum classifies fishes by their positions in food web, which provides a simple summary on the trophic structure and ecosystem function. In this study, both fish biomass and abundance trophic spectra were constructed to study the spatial and seasonal variations in the trophic structure of demersal fish assemblages in Jiaozhou Bay, China. Data were collected from four seasonal bottom trawl surveys in Jiaozhou Bay from February to November in 2011. Trophic levels (TLs) of fishes were determined by nitrogen stable isotope analysis. This study indicated that most of these trophic spectra had a single peak at trophic level (TL) of 3.4-3.7, suggesting that demersal fish assemblages of Jiaozhou Bay were dominated by secondary consumers (eg. Pholis fangi and Amblychaeturichthys hexanema). The spatial and seasonal variations of trophic spectra of Jiaozhou Bay reflected the influence of fish reproduction, fishing pressure and migration of fishes. Two-way analysis of variance (ANOVA) showed that seasonal variations in trophic spectra in Jiaozhou Bay were significant ( P0.05). The trophic spectrum has been proved to be a useful tool to monitor the trophic structure of fish assemblages. This study highlighted the comprehensive application of fish biomass and abundance trophic spectra in the study on trophic structure of fish assemblages.

  10. Tectonic evolution and mantle structure of the Caribbean

    Science.gov (United States)

    Benthem, Steven; Govers, Rob; Spakman, Wim; Wortel, Rinus

    2013-06-01

    investigate whether predictions of mantle structure from tectonic reconstructions are in agreement with a detailed tomographic image of seismic P wave velocity structure under the Caribbean region. In the upper mantle, positive seismic anomalies are imaged under the Lesser Antilles and Puerto Rico. These anomalies are interpreted as remnants of Atlantic lithosphere subduction and confirm tectonic reconstructions that suggest at least 1100 km of convergence at the Lesser Antilles island arc during the past ~45 Myr. The imaged Lesser Antilles slab consists of a northern and southern anomaly, separated by a low-velocity anomaly across most of the upper mantle, which we interpret as the subducted North America-South America plate boundary. The southern edge of the imaged Lesser Antilles slab agrees with vertical tearing of South America lithosphere. The northern Lesser Antilles slab is continuous with the Puerto Rico slab along the northeastern plate boundary. This results in an amphitheater-shaped slab, and it is interpreted as westward subducting North America lithosphere that remained attached to the surface along the northeastern boundary of the Caribbean plate. At the Muertos Trough, however, material is imaged until a depth of only 100 km, suggesting a small amount of subduction. The location and length of the imaged South Caribbean slab agrees with proposed subduction of Caribbean lithosphere under the northern South America plate. An anomaly related to proposed Oligocene subduction at the Nicaragua rise is absent in the tomographic model. Beneath Panama, a subduction window exists across the upper mantle, which is related to the cessation of subduction of the Nazca plate under Panama since 9.5 Ma and possibly the preceding subduction of the extinct Cocos-Nazca spreading center. In the lower mantle, two large anomaly patterns are imaged. The westernmost anomaly agrees with the subduction of Farallon lithosphere. The second lower mantle anomaly is found east of

  11. Consumer–brand assemblages in advertising

    DEFF Research Database (Denmark)

    Bjerrisgaard, Sofie Møller; Kjeldgaard, Dannie; Bengtson, Anders

    2013-01-01

    This paper discusses how the use of tattoos in advertising renders diverse brand–consumer assemblages visible. In considering advertising practitioners as professionals of entanglement, the paper emphasizes the embeddedness of practitioners’ use of tattoo symbolism in institutionalized marketing...... systems and in the cultural history of tattooing. In accordance with recent emphasis on the importance of material devices for understanding contemporary sociality, this paper presents a semiotic analysis of a convenience sample of advertisements depicting tattoos. Tattoos are productive for the study...... potency. This analysis demonstrates how the emergence of brand tattoos in advertising challenges the dominant consumer centrism in consumer research and suggests a networked, emerging understanding of the subject in which agency is distributed in socio-technical assemblages....

  12. User Assemblages in Design: An Ethnographic Study

    OpenAIRE

    Wilkie, Alex

    2010-01-01

    This thesis presents an ethnographic study of the role of users in user-centered design. It is written from the perspective of science and technology studies, in particular developments in actor-network theory, and draws on the notion of the assemblage from the work of Deleuze and Guattari. The data for this thesis derives from a six-month field study of the routine discourse and practices of user-centered designers working for a multinational microprocessor manufacturer. The central argument...

  13. HUMAN GIARDIASIS IN MALAYSIA: CORRELATION BETWEEN THE PRESENCE OF CLINICAL MANIFESTATION AND GIARDIA INTESTINALIS ASSEMBLAGE.

    Science.gov (United States)

    Anuar, Tengku Shahrul; Moktar, Norhayati; Salleh, Fatmah Md; Al-Mekhlafi, Hesham M

    2015-09-01

    Clinical manifestations of giardiasis vary from asymptomatic infection to chronic diarrhea. A total of 611 stool samples from Aboriginal participants residing in Jelebu, Gerik and Temerloh States, Malaysia, ages 2 to 74 years were screened for Giardia intestinalis using microscopic examination and sequence analysis of a fragment of nested-PCR amplified triosephosphate isomerase (tpi) gene. Demographic data was collected through a structured questionnaire. tpi was successfully amplified from 98/110 samples microscopically positive for G. intestinalis, with 62 and 36 belonging to assemblage A and B, respectively. There is a significant correlation between assemblage A and symptomatic infection only in participants of < 15 years of age. In the other age group, host factors may have more effects on the presence of clinical signs and symptoms than G. intestinalis assemblage types. PMID:26863854

  14. Toward a Social Ontology for Science Education: Introducing Deleuze and Guattari's Assemblages

    Science.gov (United States)

    Bazzul, Jesse; Kayumova, Shakhnoza

    2016-01-01

    This essay's main objective is to develop a theoretical, ontological basis for critical, social justice-oriented science education. Using Deleuze and Guattari's notion of assemblages, rhizomes, and arborescent structures, this article challenges authoritarian institutional practices, as well as the subject of these practices, and offers a way for…

  15. Assemblage characteristics and diet of fish in the shallow coastal waters of James Ross Island, Antarctica

    Czech Academy of Sciences Publication Activity Database

    Jurajda, Pavel; Roche, Kevin Francis; Sedláček, I.; Všetičková, Lucie

    (2016). ISSN 0722-4060 R&D Projects: GA ČR GBP505/12/G112 Institutional support: RVO:68081766 Keywords : Antarctic Peninsula * Fish assemblage structure * Notothenioidei * Shallow coastal waters * Ice pack * Czech Antarctic Station Subject RIV: EH - Ecology, Behaviour Impact factor: 1.586, year: 2014

  16. Niche partitioning and species coexistence in a Neotropical felid assemblage

    Science.gov (United States)

    Di Bitetti, Mario S.; De Angelo, Carlos D.; Di Blanco, Yamil E.; Paviolo, Agustín

    2010-07-01

    Carnivores have been used as a model to understand the effects of competition in community structure. Behavioral mechanisms that facilitate species coexistence have been poorly explored and may explain the lack of community-wide morphological character displacement in some carnivore assemblages. We use the results of large-scale and intensive camera-trap surveys conducted in the Atlantic Forest of NE Argentina between 2003 and 2008 to describe the spatial patterns of detection and the daily pattern of records of the six wild cat species present in the region (jaguar Panthera onca, puma Puma concolor, ocelot Leopardus pardalis, jaguarundi Puma yagouaroundi, margay Leopardus wiedii, and oncilla Leopardus tigrinus). We use these patterns to generate hypotheses about behavioral differences that may facilitate species coexistence. The larger species were more frequently recorded in the better-protected areas, probably as a result of anthropogenic effects (poaching of cats and their prey). Competitive release from ocelots and jaguarundis may explain why the oncilla and the margay showed the opposite pattern. Morphologically similar species had the most contrasting activity patterns: the margay was exclusively nocturnal and the jaguarundi diurnal. The other species were cathemeral, but alternated their peaks of activity in relation to the relative order of their body weights. The contrasting temporal patterns observed and the ability of pumas and oncillas to adjust their activity patterns to local conditions may facilitate the coexistence of these cat species and explain the lack of character displacement in this assemblage.

  17. Presence of riparian vegetation increases biotic condition of fish assemblages in two Brazilian reservoirs

    Directory of Open Access Journals (Sweden)

    Fabio Cop Ferreira

    2015-09-01

    Full Text Available Abstract The riparian vegetation in lakes and reservoirs is source of course wood structures such as trunks and branches and is used as sheltering, spawning and foraging habitats for fishes. The reduction of these submerged structures can thus, affect the composition and structure of fish assemblages in reservoirs. Aim To evaluate the influence of riparian vegetation on the biotic condition of fish assemblage by adapting the Reservoir Fish Assemblage Index (RFAI to two reservoirs in the Upper Paranapanema river basin, São Paulo State, Brazil. Methods The RFAI was adapted from metrics related to the functional characteristics and composition of fish assemblages through a protocol of metric selection and validation, and to its response to the presence of riparian vegetation. Results The final RFAI was composed by nine metrics, been lower in sites without riparian vegetation as consequence of the predominance of larger individuals and the percent of piscivorous and detritivorous fishes. Conclusions These results suggest that increasing shore habitat complexity in reservoirs by maintaining riparian vegetation increases fish biotic integrity.

  18. Explaining dissimilarities in macroinvertebrate assemblages among stream sites using environmental variables

    Directory of Open Access Journals (Sweden)

    Adriano S. Melo

    2009-03-01

    Full Text Available The relationship between community structure and environmental factors usually varies according to ecosystem type, group of organisms, and spatial scale. In this study I assessed whether dissimilarities among assemblages of stream macroinvertebrates are related to differences in environmental variables. Data consisted of macroinvertebrate samples of 10 stream sites during the dry season. Seven environmental variables were assessed. The relationship among dissimilarities in assemblage structure and dissimilarities in environmental variables was assessed using the BioEnv approach. Conductivity and measures related to stream size were the most important variables. However, part of the correlation with conductivity was due to the high value observed in a single stream site, which presented a relatively distinct macroinvertebrate fauna. There was an abrupt change in assemblage structure between 4th and 5th order streams. Although the study included a single 5th order site and thus only weak generalizations are possible, this finding corroborates scattered evidence observed in previous studies. The finding that nearby sites may harbor distinct macroinvertebrate assemblages implies whole-catchment conservation strategies. As most of the remaining Atlantic Rain Forest is restricted to small fragments, restoration projects near fragments should be implemented so as to properly conserve lotic ecosystems.

  19. Rapid assessment of stony coral richness and condition on Saba Bank, Netherlands Antilles.

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    Sheila A McKenna

    Full Text Available The benthic habitats of Saba Bank (17 degrees 25'N, 63 degrees 30'W are at risk from maritime traffic, especially oil tankers (e.g., anchoring. To mitigate this risk, information is needed on the biodiversity and location of habitats to develop a zone use plan. A rapid survey to document the biodiversity of macro-algae, sponges, corals and fishes was conducted. Here we report on the richness and condition of stony coral species at 18 select sites, and we test for the effects of bottom type, depth, and distance from platform edge. Species richness was visually assessed by roving scuba diver with voucher specimens of each species collected. Coral tissue was examined for bleaching and diseases. Thirty-three coral species were documented. There were no significant differences in coral composition among bottom types or depth classes (ANOSIM, P>0.05. There was a significant difference between sites (ANOSIM, P<0.05 near and far from the platform edge. The number of coral species observed ranged from zero and one in algal dominated habitats to 23 at a reef habitat on the southern edge of the Bank. Five reef sites had stands of Acropora cervicornis, a critically endangered species on the IUCN redlist. Bleaching was evident at 82% of the sites assessed with 43 colonies bleached. Only three coral colonies were observed to have disease. Combining our findings with that of other studies, a total of 43 species have been documented from Saba Bank. The coral assemblage on the bank is representative and typical of those found elsewhere in the Caribbean. Although our findings will help develop effective protection, more information is needed on Saba Bank to create a comprehensive zone use plan. Nevertheless, immediate action is warranted to protect the diverse coral reef habitats documented here, especially those containing A. cervicornis.

  20. Seasonal variability of morphospaces in a subtropical fish assemblage

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    Carolina Correia Siliprandi

    2015-11-01

    Full Text Available Morphological characters of fishes are essential to evaluate the functional structure of assemblages, being morphological differences indicative of distinct ecological and adaptive strategies. The ecomorphology using morphospaces analyzes the structure of a fish assemblage through the values of intervals between homologous points positioned in anatomical structures of organisms phylogenetically related. These intervals can be quantified by morphogeometric and multivariate analyses. Seasonally during 2013-2014, standardized images were obtained from fishes sampled in Araça Bay, São Sebastião District, Brazil, using nine fishing gears which were grouped to verify the species occurrence variation. Qualitative approach (presence/absence data was used to carry out morphological analyses. A total of 27 landmarks and semilandmarks with anatomical, ecological and taxonomical meaning were positioned in species images of the left profile. Consensus figures were made embedding the intraspecific variability. Uniform components of the shape variation (RWs were generated. To build morphospaces, the first eight RWs were considered (explain more than 95% of the total morphological variability and were defined using Convex Hull. The RWs were also used to calculate the Morphological Richness (MR, Morphological Disparity (MD and Morphogeometric Index (EMI. The MD indicates the morphospace size and showed greater values in summer (0.051 and winter (0.047 as MR, related to the higher number of species (MRsummer=7.93; MRwinter=8.65. During all the year, the Araça Bay presents high diversity of fishes. Nevertheless, winter and summer seasons reached the highest diversity, periods when horizontal mobile fishes with elongated shapes arrive to the region, implying an increase of morphological diversity and shape’s redundancy (represented by the lowest values of EMI: winter=0.120; summer=0.123.

  1. Functional redundancy patterns reveal non-random assembly rules in a species-rich marine assemblage.

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    Nicolas Guillemot

    Full Text Available The relationship between species and the functional diversity of assemblages is fundamental in ecology because it contains key information on functional redundancy, and functionally redundant ecosystems are thought to be more resilient, resistant and stable. However, this relationship is poorly understood and undocumented for species-rich coastal marine ecosystems. Here, we used underwater visual censuses to examine the patterns of functional redundancy for one of the most diverse vertebrate assemblages, the coral reef fishes of New Caledonia, South Pacific. First, we found that the relationship between functional and species diversity displayed a non-asymptotic power-shaped curve, implying that rare functions and species mainly occur in highly diverse assemblages. Second, we showed that the distribution of species amongst possible functions was significantly different from a random distribution up to a threshold of ∼90 species/transect. Redundancy patterns for each function further revealed that some functions displayed fast rates of increase in redundancy at low species diversity, whereas others were only becoming redundant past a certain threshold. This suggested non-random assembly rules and the existence of some primordial functions that would need to be fulfilled in priority so that coral reef fish assemblages can gain a basic ecological structure. Last, we found little effect of habitat on the shape of the functional-species diversity relationship and on the redundancy of functions, although habitat is known to largely determine assemblage characteristics such as species composition, biomass, and abundance. Our study shows that low functional redundancy is characteristic of this highly diverse fish assemblage, and, therefore, that even species-rich ecosystems such as coral reefs may be vulnerable to the removal of a few keystone species.

  2. Larval assemblages of large and medium-sized pelagic species in the Straits of Florida

    Science.gov (United States)

    Richardson, David E.; Llopiz, Joel K.; Guigand, Cedric M.; Cowen, Robert K.

    2010-07-01

    Critical gaps in our understanding of the distributions, interactions, life histories and preferred habitats of large and medium-size pelagic fishes severely constrain the implementation of ecosystem-based, spatially structured fisheries management approaches. In particular, spawning distributions and the environmental characteristics associated with the early life stages are poorly documented. In this study, we consider the diversity, assemblages, and associated habitat of the larvae of large and medium-sized pelagic species collected during 2 years of monthly surveys across the Straits of Florida. In total, 36 taxa and 14,295 individuals were collected, with the highest diversity occurring during the summer and in the western, frontal region of the Florida Current. Only a few species (e.g. Thunnus obesus, T. alalunga, Tetrapturus pfluegeri) considered for this study were absent. Small scombrids (e.g. T. atlanticus, Katsuwonus pelamis, Auxis spp.) and gempylids dominated the catch and were orders of magnitude more abundant than many of the rare species (e.g. Thunnus thynnus,Kajikia albida). Both constrained (CCA) and unconstrained (NMDS) multivariate analyses revealed a number of species groupings including: (1) a summer Florida edge assemblage (e.g. Auxis spp., Euthynnus alleterattus, Istiophorus platypterus); (2) a summer offshore assemblage (e.g. Makaira nigricans, T. atlanticus, Ruvettus pretiosus, Lampris guttatus); (3) an ubiquitous assemblage (e.g. K. pelamis, Coryphaena hippurus, Xiphias gladius); and (4) a spring/winter assemblage that was widely dispersed in space (e.g. trachipterids). The primary environmental factors associated with these assemblages were sea-surface temperature (highest in summer-early fall), day length (highest in early summer), thermocline depth (shallowest on the Florida side) and fluorescence (highest on the Florida side). Overall, the results of this study provide insights into how a remarkable diversity of pelagic species

  3. Sothi-Siswal Ceramic Assemblage: A Reappraisal

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    Tejas Garge

    2010-12-01

    Full Text Available Harappan evidences in Chautan valley has a unique ceramic tradition. In the light of recent plethora of knowledge as well as against the background of the studies conducted by A. Ghosh, J.S. Nigam, Katy Frenchman, Suraj Bhan & Madhu Bala, we will have to not only reclassify the Sothi-Siswal ceramic assemblage but also alter basic nomenclatures and concepts involve in it. It will give us deep insight in to the process of evolution of Early Harappan cultures vis-à-vis the dynamic of regional cultural complexes.

  4. Large-scale patterns in morphological diversity and species assemblages in Neotropical Triatominae (Heteroptera: Reduviidae

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    Paula Nilda Fergnani

    2013-12-01

    Full Text Available We analysed the spatial variation in morphological diversity (MDiv and species richness (SR for 91 species of Neotropical Triatominae to determine the ecological relationships between SR and MDiv and to explore the roles that climate, productivity, environmental heterogeneity and the presence of biomes and rivers may play in the structuring of species assemblages. For each 110 km x 110 km-cell on a grid map of America, we determined the number of species (SR and estimated the mean Gower index (MDiv based on 12 morphological attributes. We performed bootstrapping analyses of species assemblages to identify whether those assemblages were more similar or dissimilar in their morphology than expected by chance. We applied a multi-model selection procedure and spatial explicit analyses to account for the association of diversity-environment relationships. MDiv and SR both showed a latitudinal gradient, although each peaked at different locations and were thus not strictly spatially congruent. SR decreased with temperature variability and MDiv increased with mean temperature, suggesting a predominant role for ambient energy in determining Triatominae diversity. Species that were more similar than expected by chance co-occurred near the limits of the Triatominae distribution in association with changes in environmental variables. Environmental filtering may underlie the structuring of species assemblages near their distributional limits.

  5. Comparative patterns of genetic variation among populations of the Zamia pumila L. complex across three islands of the Greater Antilles

    Science.gov (United States)

    The Zamia pumila L. complex (Cycadales: Zamiaceae) is a distinctive, monophyletic, diploid (2n =16) assemblage of populations restricted to the West Indies and southeastern U. S. (Florida) that is currently considered to encompass either a single polymorphic, or nine distinct species. We are extensi...

  6. The Paleoindian Bison Assemblage from Charlie Lake Cave, British Columbia

    OpenAIRE

    Jonathan C. Driver; Vallieres, Claudine

    2008-01-01

    A small assemblage of bison bones from the Palaeoindian (10,700 to 9500 BP) components at Charlie Lake Cave, British Columbia is dominated by elements from the middle and lower limbs. The skeletal element frequencies are not typical of a kill site. The lithic assemblage, the lack of evidence for burning, and the ratio of long bone shaft fragments to epiphyses suggest that the assemblage was not produced at a residential site nor at a specialized processing area. We propose that the assemblage...

  7. Diversity and abundance of invertebrate epifaunal assemblages associated with gorgonians are driven by colony attributes

    Science.gov (United States)

    Cúrdia, João; Carvalho, Susana; Pereira, Fábio; Guerra-García, José Manuel; Santos, Miguel N.; Cunha, Marina R.

    2015-06-01

    The present study aimed to explicitly quantify the link between the attributes of shallow-water gorgonian colonies (Octocorallia: Alcyonacea) and the ecological patterns of associated non-colonial epifaunal invertebrates. Based on multiple regression analysis, we tested the contribution of several attributes (colony height, width, and area, fractal dimension as a measure of colony complexity, lacunarity as a measure of the heterogeneity, and "colonial" epibiont cover) to abundance and taxonomic richness of associated assemblages. The results highlight the variation in the response of epifaunal assemblages to the gorgonian colony characteristics. The nature and intensity of the relationships were gorgonian species-dependent and varied from one taxonomic group to another. For both gorgonian species analyzed, the strongest predictor of species richness and abundance of the epifaunal assemblages was "colonial" epibiont cover, possibly due to a trophic effect (direct or indirect enhancement of food availability) combined with the surface available for colonization (species-area effect). Although structural complexity is usually indicated as the main driver for rich and abundant coral-associated assemblages, no significant relationship was observed between fractal dimension and the community descriptors; lacunarity, which reflects the sizes of the inter-branch spaces, was only linked to taxonomic richness in the assemblages associated with Leptogorgia lusitanica. The validity of the paradigm that structural complexity enhances biodiversity may be scale-dependent. In the case of gorgonians, the effect of complexity at the "garden" level may be more relevant than at the individual colony level. This reinforces the need for the conservation of gorgonian aggregation areas as a whole in order to preserve host diversity and size structure.

  8. Diversity and abundance of invertebrate epifaunal assemblages associated with gorgonians are driven by colony attributes

    KAUST Repository

    Curdia, Joao

    2015-03-20

    The present study aimed to explicitly quantify the link between the attributes of shallow-water gorgonian colonies (Octocorallia: Alcyonacea) and the ecological patterns of associated non-colonial epifaunal invertebrates. Based on multiple regression analysis, we tested the contribution of several attributes (colony height, width, and area, fractal dimension as a measure of colony complexity, lacunarity as a measure of the heterogeneity, and “colonial” epibiont cover) to abundance and taxonomic richness of associated assemblages. The results highlight the variation in the response of epifaunal assemblages to the gorgonian colony characteristics. The nature and intensity of the relationships were gorgonian species-dependent and varied from one taxonomic group to another. For both gorgonian species analyzed, the strongest predictor of species richness and abundance of the epifaunal assemblages was “colonial” epibiont cover, possibly due to a trophic effect (direct or indirect enhancement of food availability) combined with the surface available for colonization (species–area effect). Although structural complexity is usually indicated as the main driver for rich and abundant coral-associated assemblages, no significant relationship was observed between fractal dimension and the community descriptors; lacunarity, which reflects the sizes of the inter-branch spaces, was only linked to taxonomic richness in the assemblages associated with Leptogorgia lusitanica. The validity of the paradigm that structural complexity enhances biodiversity may be scale-dependent. In the case of gorgonians, the effect of complexity at the “garden” level may be more relevant than at the individual colony level. This reinforces the need for the conservation of gorgonian aggregation areas as a whole in order to preserve host diversity and size structure. © 2015 Springer-Verlag Berlin Heidelberg

  9. Small-scale patterns of deep-sea fish distributions and assemblages of the Grand Banks, Newfoundland continental slope

    Science.gov (United States)

    Baker, Krista D.; Haedrich, Richard L.; Snelgrove, Paul V. R.; Wareham, Vonda E.; Edinger, Evan N.; Gilkinson, Kent D.

    Deep-sea fishes are the target of directed fisheries and are considered a conservation concern. Yet, we still know little about the factors that affect deep-sea fish distributions and assemblage patterns on relatively small spatial scales. We used results from remotely operated vehicle surveys that observed 105 km (˜346 960 m2) of seafloor over a depth range of 351-2245 m in three canyons off Newfoundland to examine the occurrence, behavior, habitat specificity, and regional assemblage patterns of deep-sea fishes in this region. We found distinct assemblages based on both depth and habitat classifications. The most obvious unique assemblage was that associated with outcrops, which served as habitat for relatively rare species such as Neocyttus helgae, Hoplostethus atlanticus, and Lepidion eques. Several coral habitats hosted distinct assemblages when compared to other habitats with low or medium structural complexity. Our results illustrate that any program targeted at protecting deep-sea ecosystems must protect a wide-range of habitats and depths to conserve a variety of fish species and assemblages.

  10. Effect of riparian vegetation cover and season on aquatic macroinvertebrate assemblages in the Ecuadorian Andes

    OpenAIRE

    Gallegos-Sánchez, Silvana Andrea

    2013-01-01

    The purpose of this study was to investigate the effects of season and changes in the riparian vegetation cover on diversity, structure, temporal variability, and trophic structure of aquatic macroinvertebrate assemblage in the Sambache River, Pasochoa Wildlife Refuge, Ecuador. Macroinvertebrate samples were collected using a Surber bottom sampler during the dry and rainy seasons from sections of the river dissecting three different riparian vegetation types with varying degrees of disturbanc...

  11. Techniques de formage et d'assemblage

    CERN Document Server

    Favre, G; CERN. Geneva. TS Department

    2004-01-01

    Les sections Techniques d'Assemblage du groupe EST/MF et Brasage du groupe EST/SM ont été groupées en un seul service dans un but de rationalisation accrue des ressources et méthodes. Ce service dispose de nombreux moyens : soudure et découpe LASER (YAG, 350 W), soudure par faisceau d'électrons (deux installations, 35 et 7.5 kW), équipements TIG orbital, jet line, MIG, soudure plasma, boîte à gants, portique de soudage trois axes multiprocédés, presses plieuses, rouleuses, moyens de repoussage, alimentation à induction 12 kW et divers fours sous vide et à air. Le service est composé de 17 personnes dont la polyvalence est encouragée. Les activités de la section seront décrites à travers quelques exemples significatifs récents, notamment : l'assemblage des amenées de courant HTS, la réalisation des chambres LSS, des tubes HET, d'enveloppes céramiques pour détecteurs PET-HPD, le brasage de RFQ, la soudure du Barrel d'ATLAS ou encore le soudage des lignes de thermalisation du toroïde d'AT...

  12. Detection of Giardia duodenalis assemblages A and B in human feces by simple, assemblage-specific PCR assays.

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    Ilaria Vanni

    Full Text Available The flagellated protozoan Giardia duodenalis is a common gastrointestinal parasite of mammals, including humans. Molecular characterizations have shown the existence of eight genetic groups (or assemblages in the G. duodenalis species complex. Human infections are caused by assemblages A and B, which infect other mammals as well. Whether transmission routes, animal reservoirs and associations with specific symptoms differ for assemblage A and assemblage B is not clear. Furthermore, the occurrence and clinical significance of mixed (A+B infections is also poorly understood. To date, the majority of PCR assays has been developed to identify all G. duodenalis assemblages based on the use of primers that bind to conserved regions, yet a reliable identification of specific assemblages is better achieved by ad hoc methods. The aim of this work was to design simple PCR assays that, based on the use of assemblage-specific primers, produce diagnostic bands of different lengths for assemblage A and B. We first generated novel sequence information from assemblage B, identified homologous sequences in the assemblage A genome, and designed primers at six independent loci. Experiments performed on DNA extracted from axenic cultures showed that two of the six assays can detect the equivalent of a single cyst and are not negatively influenced by disproportions between DNA of each assemblage, at least up to a 9:1 ratio. Further experiments on DNAs extracted from feces showed that the two assays can detect both assemblages in single tube reactions with excellent reliability. Finally, the robustness of these assays was demonstrated by testing a large collection of human isolates previously typed by multi-locus genotyping.

  13. The response of chironomid assemblages to mineral richness gradient in the Western Carpathian helocrenes

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    Vít Syrovátka

    2012-10-01

    Full Text Available Chironomid assemblages of helocrene springs were investigated in the Western Carpathians in order to identify potential effect of water mineral richness on the taxonomic structure of the assemblages. A complex gradient considering water chemistry and substratum was used as a measure of basicity (mineral richness. Taxonomic structure, total abundance and abundance of most frequent taxa were related to this gradient with regards to two contrasting habitats: trickle (A and water-loged soil with standing water (B. The variance in chironomid assemblage attributable to basicity was estimated and tested via PERMANOVA as well as the possible effect of the other environmental variables. The response of individual taxa was examined using GAM. The results indicate a strong relationship between basicity and substratum characteristics, with coarser mineral substrata at basic and high amount of organic matter at acidic conditions. Although water chemistry was correlated with and inseparable from these substratum properties, it could not be substituted with them, as they discriminated well only between acidic and basic springs, but did not follow the basicity gradient in either acidic or basic group of springs. Chironomid assemblage showed a strong and systematic response to the complex gradient of mineral richness, which explained the largest portion of variance in both the habitat A and B faunal data and was projected on the first axes of both NMDS ordinations. The assemblage response could be documented by the preference of several taxa for particular mineral richness conditions, while the number of taxa seemed to be highest in the middle of the basicity gradient. As only 17 samples were analysed so far, the results are considered preliminary and, hopefully, more confident results will be available in near future.doi: 10.5324/fn.v31i0.1403.Published online: 17 October 2012.

  14. No detectable effect of lionfish (Pterois volitans and P. miles) invasion on a healthy reef fish assemblage in Archipelago Los Roques National Park, Venezuela

    OpenAIRE

    Elise, S.; Urbina-Barreto, I.; Boadas-Gil, H.; Galindo-Vivas, M.; Kulbicki, Michel

    2015-01-01

    There is an increasing concern that invasive lionfish will have dramatic impacts on native reef fish assemblages in the Caribbean. However, the intensity and speed of such changes will probably depend on the initial structure of each assemblage and on the lionfish population characteristics. The species composition of native fishes, diet and size structures were analyzed on a protected Venezuelan reef, through visual census on zones with and without lionfish, 1 and 3 years after the first sig...

  15. Zooplankton assemblages in montane lakes and ponds of Mount Rainier National Park, Washington State, USA

    Science.gov (United States)

    Larson, G.L.; Hoffman, R.; McIntire, C.D.; Lienkaemper, G.; Samora, B.

    2009-01-01

    Water quality and zooplankton samples were collected during the ice-free periods between 1988 and 2005 from 103 oligotrophic montane lakes and ponds located in low forest to alpine vegetation zones in Mount Rainier National Park, Washington State, USA. Collectively, 45 rotifer and 44 crustacean taxa were identified. Most of the numerically dominant taxa appeared to have wide niche breadths. The average number of taxa per lake decreased with elevation and generally increased as maximum lake depths increased (especially for rotifers). With one exception, fish presence/absence did not explain the taxonomic compositions of crustacean zooplankton assemblages. Many rotifer species were common members of zooplankton assemblages in montane lakes and ponds in western North America, whereas the crustacean taxa were common to some areas of the west, but not others. Constraints of the environmental variables did not appear to provide strong gradients to separate the distributions of most zooplankton species. This suggests that interspecific competitive interactions and stochastic processes regulate the taxonomic structures of the zooplankton assemblages at the landscape level. Crustacean species that had broad niche breadths were associated with different rotifer taxa across the environmental gradients. Studies of zooplankton assemblages need to address both crustacean and rotifer taxa, not one or the other.

  16. Iterative evolution of sympatric seacow (Dugongidae, Sirenia assemblages during the past ~26 million years.

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    Jorge Velez-Juarbe

    Full Text Available Extant sirenians show allopatric distributions throughout most of their range. However, their fossil record shows evidence of multispecies communities throughout most of the past ∼26 million years, in different oceanic basins. Morphological differences among co-occurring sirenian taxa suggest that resource partitioning played a role in structuring these communities. We examined body size and ecomorphological differences (e.g., rostral deflection and tusk morphology among sirenian assemblages from the late Oligocene of Florida, early Miocene of India and early Pliocene of Mexico; each with three species of the family Dugongidae. Although overlapping in several ecomorphological traits, each assemblage showed at least one dominant trait in which coexisting species differed. Fossil sirenian occurrences occasionally are monotypic, but the assemblages analyzed herein show iterative evolution of multispecies communities, a phenomenon unparalleled in extant sirenian ecology. As primary consumers of seagrasses, these communities likely had a strong impact on past seagrass ecology and diversity, although the sparse fossil record of seagrasses limits direct comparisons. Nonetheless, our results provide robust support for previous suggestions that some sirenians in these extinct assemblages served as keystone species, controlling the dominance of climax seagrass species, permitting more taxonomically diverse seagrass beds (and sirenian communities than many of those observed today.

  17. Differential response of fish assemblages to coral reef-based seaweed farming.

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    E James Hehre

    Full Text Available As the global demand for seaweed-derived products drives the expansion of seaweed farming onto shallow coral ecosystems, the effects of farms on fish assemblages remain largely unexplored. Shallow coral reefs provide food and shelter for highly diverse fish assemblages but are increasingly modified by anthropogenic activities. We hypothesized that the introduction of seaweed farms into degraded shallow coral reefs had potential to generate ecological benefits for fish by adding structural complexity and a possible food source. We conducted 210 transects at 14 locations, with sampling stratified across seaweed farms and sites adjacent to and distant from farms. At a seascape scale, locations were classified by their level of exposure to human disturbance. We compared sites where (1 marine protected areas (MPAs were established, (2 neither MPAs nor blast fishing was present (hence "unprotected", and (3 blast fishing occurred. We observed 80,186 fish representing 148 species from 38 families. The negative effects of seaweed farms on fish assemblages appeared stronger in the absence of blast fishing and were strongest when MPAs were present, likely reflecting the positive influence of the MPAs on fish within them. Species differentiating fish assemblages with respect to seaweed farming and disturbance were typically small but also included two key target species. The propensity for seaweed farms to increase fish diversity, abundance, and biomass is limited and may reduce MPA benefits. We suggest that careful consideration be given to the placement of seaweed farms relative to MPAs.

  18. The scales of variability of stream fish assemblage at tributary confluences

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    István Czeglédi

    2015-12-01

    Full Text Available Tributary confluences play an important role in the dispersal of organisms, and consequently, in shaping regional scale diversity in stream networks. Despite their importance in dispersal processes, little is known about how ecological assemblages are organized in these habitats. We studied the scales of variability of stream fish assemblages over three seasons using a hierarchical sampling design, which incorporated three tributaries, three sites at the mouth of each tributary and using four sampling units at each site. We found strong scale dependent variability in species richness, composition and relative abundance. Most of the variation was accounted for by the interactive effect of season, between stream and between site effects, while habitat structure of the sampling units had a relatively minor role. Species richness showed a continuous decrease from the mainstem river in most cases, while species composition and relative abundance changed less consistently along the longitudinal profile. Consequently, we found that not only the junctions presented a strong filter on the species pool, but some species were filtered out if they passed this critical habitat bottleneck. Spatial position of the tributaries along the river also contributed to assemblage variability in the confluences. Overall, our results suggest high variability in fish assemblages across multiple scales at tributary confluences. Environmental management should take a more critical care on the filtering role of tributary confluences in species dispersal, for better understanding patterns and processes in the branches of dendritic stream networks.

  19. Spatial and temporal dynamics of drosophilid larval assemblages associated to fruits

    Directory of Open Access Journals (Sweden)

    Renata Alves da Mata

    2015-03-01

    Full Text Available The study of organisms and their resources is critical to further understanding population dynamics in space and time. Although drosophilids have been widely used as biological models, their relationship with breeding and feeding sites has received little attention. Here, we investigate drosophilids breeding in fruits in the Brazilian Savanna, in two contrasting vegetation types, throughout 16 months. Specifically, larval assemblages were compared between savannas and forests, as well as between rainy and dry seasons. The relationships between resource availability and drosophilid abundance and richness were also tested. The community (4,022 drosophilids of 23 species and 2,496 fruits of 57 plant taxa varied widely in space and time. Drosophilid assemblages experienced a strong bottleneck during the dry season, decreasing to only 0.5% of the abundance of the rainy season. Additionally, savannas displayed lower richness and higher abundance than the forests, and were dominated by exotic species. Both differences in larval assemblages throughout the year and between savannas and gallery forests are consistent with those previously seen in adults. Although the causes of this dynamic are clearly multifactorial, resource availability (richness and abundance of rotten fruits was a good predictor of the fly assemblage structure.

  20. Predicting ecological changes on benthic estuarine assemblages through decadal climate trends along Brazilian Marine Ecoregions

    Science.gov (United States)

    Bernardino, Angelo F.; Netto, Sérgio A.; Pagliosa, Paulo R.; Barros, Francisco; Christofoletti, Ronaldo A.; Rosa Filho, José S.; Colling, André; Lana, Paulo C.

    2015-12-01

    Estuaries are threatened coastal ecosystems that support relevant ecological functions worldwide. The predicted global climate changes demand actions to understand, anticipate and avoid further damage to estuarine habitats. In this study we reviewed data on polychaete assemblages, as a surrogate for overall benthic communities, from 51 estuaries along five Marine Ecoregions of Brazil (Amazonia, NE Brazil, E Brazil, SE Brazil and Rio Grande). We critically evaluated the adaptive capacity and ultimately the resilience to decadal changes in temperature and rainfall of the polychaete assemblages. As a support for theoretical predictions on changes linked to global warming we compared the variability of benthic assemblages across the ecoregions with a 40-year time series of temperature and rainfall data. We found a significant upward trend in temperature during the last four decades at all marine ecoregions of Brazil, while rainfall increase was restricted to the SE Brazil ecoregion. Benthic assemblages and climate trends varied significantly among and within ecoregions. The high variability in climate patterns in estuaries within the same ecoregion may lead to correspondingly high levels of noise on the expected responses of benthic fauna. Nonetheless, we expect changes in community structure and productivity of benthic species at marine ecoregions under increasing influence of higher temperatures, extreme events and pollution.

  1. Assessment of fish assemblages in coastal lagoon habitats: Effect of sampling method

    Science.gov (United States)

    Franco, A.; Pérez-Ruzafa, A.; Drouineau, H.; Franzoi, P.; Koutrakis, E. T.; Lepage, M.; Verdiell-Cubedo, D.; Bouchoucha, M.; López-Capel, A.; Riccato, F.; Sapounidis, A.; Marcos, C.; Oliva-Paterna, F. J.; Torralva-Forero, M.; Torricelli, P.

    2012-10-01

    The structure of fish assemblages accounted for by different sampling methods (namely fyke net, seine nets, visual census) applied to vegetated and unvegetated lagoon habitats was investigated in terms of species composition, functional groups (ecological and trophic guilds), and fish size distribution. Significant differences were detected among methods, even among similar ones (seine nets). Visual census and fyke net detected more easily pelagic species, allowing the sampling of larger fish, whereas seine nets targeted more efficiently benthic-demersal species, with a dominance of 2-10 cm size classes in the fish catches. Differences were detected also among habitats, reflecting the different fish assemblages associated to vegetated and unvegetated habitats in coastal lagoons and transitional waters. However a different ability of discriminating between habitat-associated fish assemblages was recorded for the sampling methods. The different selectivity and functioning of the tested sampling methods confirm the importance of considering the targeted scale at which the research is being carried out, as well as the method that will be used to assess the ecological status of lagoon fish assemblages when choosing the most appropriate sampling method. A cross-validation of fish sampling methodologies in transitional waters is necessary to cope with the mandatory of the Water Framework Directive of standardization and comparability of monitoring methods.

  2. 3-D linear inversion of gravity data: method and application to Basse-Terre volcanic island, Guadeloupe, Lesser Antilles

    Science.gov (United States)

    Barnoud, Anne; Coutant, Olivier; Bouligand, Claire; Gunawan, Hendra; Deroussi, Sébastien

    2016-04-01

    We use a Bayesian formalism combined with a grid node discretization for the linear inversion of gravimetric data in terms of 3-D density distribution. The forward modelling and the inversion method are derived from seismological inversion techniques in order to facilitate joint inversion or interpretation of density and seismic velocity models. The Bayesian formulation introduces covariance matrices on model parameters to regularize the ill-posed problem and reduce the non-uniqueness of the solution. This formalism favours smooth solutions and allows us to specify a spatial correlation length and to perform inversions at multiple scales. We also extract resolution parameters from the resolution matrix to discuss how well our density models are resolved. This method is applied to the inversion of data from the volcanic island of Basse-Terre in Guadeloupe, Lesser Antilles. A series of synthetic tests are performed to investigate advantages and limitations of the methodology in this context. This study results in the first 3-D density models of the island of Basse-Terre for which we identify: (i) a southward decrease of densities parallel to the migration of volcanic activity within the island, (ii) three dense anomalies beneath Petite Plaine Valley, Beaugendre Valley and the Grande-Découverte-Carmichaël-Soufrière Complex that may reflect the trace of former major volcanic feeding systems, (iii) shallow low-density anomalies in the southern part of Basse-Terre, especially around La Soufrière active volcano, Piton de Bouillante edifice and along the western coast, reflecting the presence of hydrothermal systems and fractured and altered rocks.

  3. Searching for unconventional seismic signals on a subduction zone with a submerged forearc: OBS offshore the Lesser Antilles

    Science.gov (United States)

    Bécel, Anne; Diaz, Jordi; Laigle, Mireille; Hirn, Alfred

    2013-09-01

    Detecting unconventional seismic signals related to subduction zone processes at depth in continuous ocean bottom seismometer (OBS) records requires the analysis and identification of noise due to instrumental problems, deployment sites or sea state conditions. The temporary OBS deployment at the Lesser Antilles subduction zone provides new insights into the feasibility of detecting unconventional signals such as non volcanic tremor (NVT), long-period (LP) or ultra-long period (ULP) events. Analysis of noise at an array comprising several sites and types of instruments and comparison with recordings on land shows transients in the noise. Episodes can be identified considering the diversity of sites and instrument types and comparing the seismic signals with meteorological and oceanographic data. In order to reliably detect NVT (1-10 Hz) originating from inside the solid Earth, one must first characterize noise induced by the activity of the atmosphere and hydrosphere at the sea-bottom as well as on land. The semidiurnal modulation of noise amplitude can be shown here not to be due to that of the NVT from a seismic source at depth which is related to the subduction interplate and whose activity is modulated by the tidal stresses as inferred for other megathrusts on emerged forearcs. Here, the semidiurnal modulation is rather due to the effect of the tides themselves, such as tidal currents, since they do not affect all types and all components of the unique multi-station array of OBS that could be deployed on this submerged forearc. The short period cut-off of the strong noise due to ocean surface infragravity waves increases to longer periods with OBS depth, thereby increasing the observational window with low noise to lower frequencies, and deep OBS sites may be advantageous for detecting LP events.

  4. Spatial segregation in eastern North Pacific skate assemblages.

    Science.gov (United States)

    Bizzarro, Joseph J; Broms, Kristin M; Logsdon, Miles G; Ebert, David A; Yoklavich, Mary M; Kuhnz, Linda A; Summers, Adam P

    2014-01-01

    Skates (Rajiformes: Rajoidei) are common mesopredators in marine benthic communities. The spatial associations of individual species and the structure of assemblages are of considerable importance for effective monitoring and management of exploited skate populations. This study investigated the spatial associations of eastern North Pacific (ENP) skates in continental shelf and upper continental slope waters of two regions: central California and the western Gulf of Alaska. Long-term survey data were analyzed using GIS/spatial analysis techniques and regression models to determine distribution (by depth, temperature, and latitude/longitude) and relative abundance of the dominant species in each region. Submersible video data were incorporated for California to facilitate habitat association analysis. We addressed three main questions: 1) Are there regions of differential importance to skates?, 2) Are ENP skate assemblages spatially segregated?, and 3) When skates co-occur, do they differ in size? Skate populations were highly clustered in both regions, on scales of 10s of kilometers; however, high-density regions (i.e., hot spots) were segregated among species. Skate densities and frequencies of occurrence were substantially lower in Alaska as compared to California. Although skates are generally found on soft sediment habitats, Raja rhina exhibited the strongest association with mixed substrates, and R. stellulata catches were greatest on rocky reefs. Size segregation was evident in regions where species overlapped substantially in geographic and depth distribution (e.g., R. rhina and Bathyraja kincaidii off California; B. aleutica and B. interrupta in the Gulf of Alaska). Spatial niche differentiation in skates appears to be more pronounced than previously reported. PMID:25329312

  5. Spatial segregation in eastern North Pacific skate assemblages.

    Directory of Open Access Journals (Sweden)

    Joseph J Bizzarro

    Full Text Available Skates (Rajiformes: Rajoidei are common mesopredators in marine benthic communities. The spatial associations of individual species and the structure of assemblages are of considerable importance for effective monitoring and management of exploited skate populations. This study investigated the spatial associations of eastern North Pacific (ENP skates in continental shelf and upper continental slope waters of two regions: central California and the western Gulf of Alaska. Long-term survey data were analyzed using GIS/spatial analysis techniques and regression models to determine distribution (by depth, temperature, and latitude/longitude and relative abundance of the dominant species in each region. Submersible video data were incorporated for California to facilitate habitat association analysis. We addressed three main questions: 1 Are there regions of differential importance to skates?, 2 Are ENP skate assemblages spatially segregated?, and 3 When skates co-occur, do they differ in size? Skate populations were highly clustered in both regions, on scales of 10s of kilometers; however, high-density regions (i.e., hot spots were segregated among species. Skate densities and frequencies of occurrence were substantially lower in Alaska as compared to California. Although skates are generally found on soft sediment habitats, Raja rhina exhibited the strongest association with mixed substrates, and R. stellulata catches were greatest on rocky reefs. Size segregation was evident in regions where species overlapped substantially in geographic and depth distribution (e.g., R. rhina and Bathyraja kincaidii off California; B. aleutica and B. interrupta in the Gulf of Alaska. Spatial niche differentiation in skates appears to be more pronounced than previously reported.

  6. Muon tomography of the Soufrière of Guadeloupe (Lesser Antilles): Comparison with other geophysical imaging methods and assessment of volcanic risks

    Science.gov (United States)

    Gibert, D.; Lesparre, N.; Marteau, J.; Taisne, B.; Nicollin, F.; Coutant, O.

    2011-12-01

    Density tomography of rock with muons of cosmic origin measures the attenuation of the flux of particles crossing the object of interest to derive its opacity, i.e. the quantity of matter encountered by the particles along their trajectories. Recent progress in micro-electronics and particle detectors make field measurement possible and muon density tomography is gaining a growing interest (e.g. Tanaka et al., 2010; Gibert et al., 2010). We have constructed field telescopes based on the detectors of the OPERA experiment devoted to study neutrino oscillation (Lesparre et al., 2011a). Each telescope may be equipped with a variable number of detection matrices with 256 pixels. The spatial resolution is adaptable and is typically of about 20 meters (Lesparre et al., 2010). The telescopes are portable autonomous devices able to operate in harsh field conditions encountered on tropical volcanoes. The total power consumption is less than 40W, and an Ethernet link allows data downloading and remote control of the electronic devices and on-board computers. Larger high-resolution telescopes are under construction. The instruments have been successfully tested on the Etna and Soufrière of Guadeloupe volcanoes were a telescope is operating continuously since Summer 2010. Muon radiographies of the Soufrière lava dome reveal its very heterogeneous density structure produced by an intense hydrothermal circulation of acid fluids which alters its mechanical integrity leading to a high risk level of destabilisation. Small-size features are visible on the images and provide precious informations on the structure of the upper hydrothermal systems. Joined interpretation with other geophysical data available on the Soufrière - seismic tomography, electrical resistivity tomography, gravity data - is presented and discussed. Density muon tomography of the internal structure of volcanoes like the Soufrière brings important informations for the hazard evaluation an is particularly

  7. Fish Assemblages on Estuarine Artificial Reefs: Natural Rocky-Reef Mimics or Discrete Assemblages?

    OpenAIRE

    Folpp, Heath; Lowry, Michael; Gregson, Marcus; Suthers, Iain M.

    2013-01-01

    If the primary goal of artificial reef construction is the creation of additional reef habitat that is comparable to adjacent natural rocky-reef, then performance should be evaluated using simultaneous comparisons with adjacent natural habitats. Using baited remote underwater video (BRUV) fish assemblages on purpose-built estuarine artificial reefs and adjacent natural rocky-reef and sand-flat were assessed 18 months post-deployment in three south-east Australian estuaries. Fish abundance, sp...

  8. Spatio-Temporal Dynamics of Exploited Groundfish Species Assemblages Faced to Environmental and Fishing Forcings: Insights from the Mauritanian Exclusive Economic Zone.

    Directory of Open Access Journals (Sweden)

    Saïkou Oumar Kidé

    Full Text Available Environmental changes and human activities can have strong impacts on biodiversity and ecosystem functioning. This study investigates how, from a quantitative point of view, simultaneously both environmental and anthropogenic factors affect species composition and abundance of exploited groundfish assemblages (i.e. target and non-target species at large spatio-temporal scales. We aim to investigate (1 the spatial and annual stability of groundfish assemblages, (2 relationships between these assemblages and structuring factors in order to better explain the dynamic of the assemblages' structure. The Mauritanian Exclusive Economic Zone (MEEZ is of particular interest as it embeds a productive ecosystem due to upwelling, producing abundant and diverse resources which constitute an attractive socio-economic development. We applied the multi-variate and multi-table STATICO method on a data set consisting of 854 hauls collected during 14-years (1997-2010 from scientific trawl surveys (species abundance, logbooks of industrial fishery (fishing effort, sea surface temperature and chlorophyll a concentration as environmental variables. Our results showed that abiotic factors drove four main persistent fish assemblages. Overall, chlorophyll a concentration and sea surface temperature mainly influenced the structure of assemblages of coastal soft bottoms and those of the offshore near rocky bottoms where upwellings held. While highest levels of fishing effort were located in the northern permanent upwelling zone, effects of this variable on species composition and abundances of assemblages were relatively low, even if not negligible in some years and areas. The temporal trajectories between environmental and fishing conditions and assemblages did not match for all the entire time series analyzed in the MEEZ, but interestingly for some specific years and areas. The quantitative approach used in this work may provide to stakeholders, scientists and fishers a

  9. Spatio-Temporal Dynamics of Exploited Groundfish Species Assemblages Faced to Environmental and Fishing Forcings: Insights from the Mauritanian Exclusive Economic Zone.

    Science.gov (United States)

    Kidé, Saïkou Oumar; Manté, Claude; Dubroca, Laurent; Demarcq, Hervé; Mérigot, Bastien

    2015-01-01

    Environmental changes and human activities can have strong impacts on biodiversity and ecosystem functioning. This study investigates how, from a quantitative point of view, simultaneously both environmental and anthropogenic factors affect species composition and abundance of exploited groundfish assemblages (i.e. target and non-target species) at large spatio-temporal scales. We aim to investigate (1) the spatial and annual stability of groundfish assemblages, (2) relationships between these assemblages and structuring factors in order to better explain the dynamic of the assemblages' structure. The Mauritanian Exclusive Economic Zone (MEEZ) is of particular interest as it embeds a productive ecosystem due to upwelling, producing abundant and diverse resources which constitute an attractive socio-economic development. We applied the multi-variate and multi-table STATICO method on a data set consisting of 854 hauls collected during 14-years (1997-2010) from scientific trawl surveys (species abundance), logbooks of industrial fishery (fishing effort), sea surface temperature and chlorophyll a concentration as environmental variables. Our results showed that abiotic factors drove four main persistent fish assemblages. Overall, chlorophyll a concentration and sea surface temperature mainly influenced the structure of assemblages of coastal soft bottoms and those of the offshore near rocky bottoms where upwellings held. While highest levels of fishing effort were located in the northern permanent upwelling zone, effects of this variable on species composition and abundances of assemblages were relatively low, even if not negligible in some years and areas. The temporal trajectories between environmental and fishing conditions and assemblages did not match for all the entire time series analyzed in the MEEZ, but interestingly for some specific years and areas. The quantitative approach used in this work may provide to stakeholders, scientists and fishers a useful

  10. Recent disturbances augment community shifts in coral assemblages in Moorea, French Polynesia

    KAUST Repository

    Pratchett, Morgan S.

    2010-09-19

    Coral reefs are often subject to disturbances that can cause enduring changes in community structure and abundance of coral reef organisms. In Moorea, French Polynesia, frequent disturbances between 1979 and 2003 caused marked shifts in taxonomic composition of coral assemblages. This study explores recent changes in live cover and taxonomic structure of coral communities on the north coast of Moorea, French Polynesia, to assess whether coral assemblages are recovering (returning to a previous Acropora-dominated state) or continuing to move towards an alternative community structure. Coral cover declined by 29.7% between July 2003 and March 2009, mostly due to loss of Acropora and Montipora spp. Coral mortality varied among habitats, with highest levels of coral loss on the outer reef slope (7-20 m depth). In contrast, there was limited change in coral cover within the lagoon, and coral cover actually increased on the reef crest. Observed changes in coral cover and composition correspond closely with the known feeding preferences and observed spatial patterns of Acanthaster planci L., though observed coral loss also coincided with at least one episode of coral bleaching, as well as persistent populations of the corallivorous starfish Culcita novaeguineae Muller & Troschel. While climate change poses an important and significant threat to the future structure and dynamics coral reef communities, outbreaks of A. planci remain a significant cause of coral loss in Moorea. More importantly, these recent disturbances have followed long-term shifts in the structure of coral assemblages, and the relative abundance of both Pocillopora and Porites continue to increase due to disproportionate losses of Acropora and Montipora. Moreover, Pocillopora and Porites dominate assemblages of juvenile corals, suggesting that there is limited potential for a return to an Acropora-dominated state, last recorded in 1979. © 2010 Springer-Verlag.

  11. Habitat contrasts reveal a shift in the trophic position of ant assemblages.

    Science.gov (United States)

    Gibb, Heloise; Cunningham, Saul A

    2011-01-01

    1. Trophic structure within a guild can be influenced by factors such as resource availability and competition. While ants occupy a wide range of positions in food webs, and ant community composition changes with habitat, it is not well understood if ant genera tend to maintain their position in the trophic structure, or if trophic position varies across habitats. 2. We used ratios of stable isotopes of carbon and nitrogen to test for differences in the trophic structure and position of assemblages of ants among habitat types. We tested for differences between assemblages in replicate sites of the land use categories: (i) pastures with old large trees; (ii) recently revegetated pastures with small young trees; and (iii) remnant woodlands. Known insect herbivores and predatory spiders provided baselines for herbivorous and predaceous arthropods. Soil samples were used to correct for the base level of isotopic enrichment at each site. 3. We found no significant interactions between land use and ant genus for isotope enrichment, indicating that trophic structure is conserved across land use categories. The fixed relative positions of genera in the trophic structure might be re-enforced by competition or some other factor. However, the entire ant assemblage had significantly lower δ(15) N values in revegetated sites, suggesting that ants feed lower down in the food chain i.e. they are more 'herbivorous' in revegetated sites. This may be a result of the high availability of plant sugars, honeydew and herbivorous arthropod prey. 4. Surprisingly, ants in remnants and pastures with trees displayed similar isotopic compositions. Interactions within ant assemblages are thus likely to be resilient to changes in land use, but ant diets in early successional habitats may reflect the simplicity of communities, which may have comparatively lower rates of saprophagy and predation. PMID:20831728

  12. Salmon nutrients are associated with the phylogenetic dispersion of riparian flowering-plant assemblages.

    Science.gov (United States)

    Hurteau, Leslie A; Mooers, Arne Ø; Reynolds, John D; Hocking, Morgan D

    2016-02-01

    A signature of nonrandom phylogenetic community structure has been interpreted as indicating community assembly processes. Significant clustering within the phylogenetic structure of a community can be caused by habitat filtering due to low nutrient availability. Nutrient limitation in temperate Pacific coastal rainforests can be alleviated to some extent by marine nutrient subsidies introduced by migrating salmon, which leave a quantitative signature on the makeup of plant communities near spawning streams. Thus, nutrient-mediated habitat filtering could be reduced by salmon nutrients. Here, we ask how salmon abundance affects the phylogenetic structure of riparian flowering plant assemblages across 50 watersheds in the Great Bear Rainforest of British Columbia, Canada. Based on a regional pool of 60 plant species, we found that assemblages become more phylogenetically dispersed and species poor adjacent to streams with higher salmon spawning density. In contrast, increased phylogenetic clumping and species richness was seen in sites with low salmon density, with steeper slopes, further from the stream edge, and within smaller watersheds. These observations are all consistent with abiotic habitat filtering and biotic competitive exclusion acting together across local and landscape-scale gradients in nutrient availability to structure assembly of riparian flowering plants. In this case, rich salmon nutrients appear to release riparian flowering-plant assemblages from the confines of a low-nutrient habitat filter that drives phylogenetic clustering. PMID:27145619

  13. The role of river longitudinal gradients, local and regional attributes in shaping frog assemblages

    Science.gov (United States)

    de Oliveira, Francisco Fonseca Ribeiro; Eterovick, Paula Cabral

    2009-09-01

    We studied anuran assemblage composition from 1st to 4th orders along two rivers in the Rio Preto State Park, southeastern Brazil. We aimed to understand how species distribution relates to local features/longitudinal gradients within a river, and to differences between rivers. We assessed climatic (temperature, humidity), chemical (water pH, dissolved oxygen, conductivity), physical (river bottom type, current), and biotic (vegetation structure) features thought to affect anuran distribution. Cluster analyses showed that species assemblages tended to be more similar among sections of the same river than between corresponding sections of different rivers, and Mantel tests showed assemblages to be spatially structured, although river features were not. The river with a mixture of open vegetation and forest at its margins sheltered higher species diversity than the one bordered by forest. Using Canonical Correspondence Analyses, we found variables related to microhabitat availability to be the best ones to explain species distribution in the adult stage, and conductivity to be the best one for the tadpole stage. The river seasonal flood pulse seems to influence availability of additional reproductive sites and tadpole dispersal. We found no evidence of gradients of tadpole abundance responding to river size or predator abundance. Considering that anuran species are spatially structured and influenced by variables that change both locally and regionally, we recommend that the whole longitudinal gradient along permanent lotic ecosystems, together with its original limnological and structural attributes, is preserved in order to ensure conservation of anuran diversity in both local and regional scales.

  14. The relationship between fish assemblages and the helminth communities of a prey fish, in a group of small shallow lakes.

    Science.gov (United States)

    Fernández, Maria V; Brugni, Norma L; Viozzi, Gustavo P; Semenas, Liliana

    2010-12-01

    Galaxias maculatus (small puyen) is an abundant native fish distributed in lakes and rivers of the Patagonia, and it is the frequent prey of other fishes, fish-eating birds, and mammals. Previous studies have shown that it is parasitized by 33 metazoan species and that the richness and composition of the parasite communities vary between lakes. The aim of the present work was to analyze the relationship between the composition of fish assemblages and the helminth component community structure of G. maculatus . Ten environmentally similar, small, shallow lakes, belonging to the Nahuel Huapi Lake basin, were chosen because of the differences in the native fish assemblages. Parasite community structure in G. maculatus varied according to the fish assemblage of each lake. The presence of the piscivorous fish Percichthys trucha regularly produced variations in the composition and richness at the component and infracommunity levels, as well as the percentage of autogenic parasite species in G. maculatus . PMID:21158611

  15. Diversidad, estructura y variación temporal del ensamble de peces asociados al arrecife coralino de Playa Mora, Bahía de Tenacatita, México Diversity, structure, and temporal variation of fish assemblages associated to Playa Mora coral reef, Tenacatita Bay, Mexico

    Directory of Open Access Journals (Sweden)

    Cristian Moisés Galván-Villa

    2011-08-01

    Full Text Available En este estudio se describe la estructura y variación temporal del ensamble de peces asociados al arrecife coralino de Playa Mora, Jalisco, México. El registro de especies se realizó mediante censos visuales en banda de 50 × 5 m, en tres diferentes épocas del año (templado-seca, cálido-húmeda y cálido-seca. Se registró un total de 5,689 peces de 64 especies. Las familias mejor representadas por su riqueza de especies fueron Labridae (7 y Pomacentridae (6. Mediante el índice de valor biológico se determinó que las especies dominantes fueron Thalassoma lucasanum, Stegastes acapulcoensis, Microspathodon dorsalis y Prionurus punctatus. Los ensambles de peces por riqueza específica y grupos tróficos presentaron cambios temporales. La época templado-seca presentó la mayor riqueza y abundancia de peces. La composición por categorías tróficas estuvo representada principalmente por peces carnívoros, los cuales fueron dominantes en el arrecife. Las especies carnívoras, carnívoras coralívoras, coralívoras obligadas, herbívoras, zooplanctívoras y parasíticas estuvieron mejor representadas en la época templada, mientras que las omnívoras aumentaron en la cálida.This study describes the structure and temporal variation of fish assemblages associated with Playa Mora coral reef, Jalisco, México. The species present were recorded with visual censuses along transects of 50 × 5 m, in three different seasons of the year (temperate-dry, warm-rainy, and warm-dry. A total of 5,689 fishes of 64 species were recorded. The best represented families according to species richness were Labridae (7 and Pomacentride (6. The biological value index determined that Thalassoma lucasanum, Stegastes acapulcoensis, Microspathodon dorsalis, and Prionu-rus punctatus were the dominant species. The fish assemblages by specific richness and trophic groups displayed temporal changes. The temperate-dry season presented the greatest richness and abundance of

  16. Long-term changes of vascular epiphyte assemblages in the tropical lowlands of Panama

    OpenAIRE

    LAUBE, STEFAN

    2006-01-01

    The study provides insights into the dynamic processes of vascular epiphyte vegetation in two host tree species of lowland forest in Panama. Further, a novel approach is presented to examine the possible role of host tree identity in the structuring of vascular epiphyte communities: For three locally common host tree species (Socratea exorrhiza, Marila laxiflora, Perebea xanthochyma) we created null models of the expected epiphyte assemblages assuming that epiphyte colonization reflected rand...

  17. Land use influences on benthic invertebrate assemblages in southern Appalachian agricultural streams

    OpenAIRE

    Bennett, Barbara Loraine Jr.

    1998-01-01

    I investigated the role of land use in structuring benthic invertebrate assemblages in agricultural streams in the French Broad River drainage in western North Carolina. I sampled six agricultural streams (3 with cleared headwaters and 3 with forested headwaters) at three points along a gradient (headwaters, a midpoint, and a downstream site). At each site, I measured a variety of physico-chemical parameters, including temperature, chlorophyll a, discharge, nutrients, and suspended solids. ...

  18. The direct and indirect effects of predators on coral reef fish assemblages

    OpenAIRE

    Zgliczynski, Brian

    2015-01-01

    The removal of apex predators is widely recognized to have broad ecological consequences for terrestrial and aquatic communities. In marine systems, the direct effects of fisheries exploitation include altering the community standing stock (biomass), species composition, and size- structure of the fish assemblage. Although the direct effects of fisheries exploitation are well documented, there is increasing evidence that the non-lethal effects of predation can also strongly influence the stru...

  19. Influence of re-flooding on phytoplankton assemblages in a temperate wetland following prolonged drought

    OpenAIRE

    Luciana Avigliano; Alicia Vinocour; Griselda Chaparro; Guillermo Tell; Luz Allende

    2014-01-01

    Wetlands can experience drying and flooding cycles which influence the dynamics of the phytoplankton assemblages. The aim of our study was to evaluate changes in the phytoplankton structure during a drought/flood period in a warm-temperate wetland. We hypothesized that fluctuations in water level and development of macrophytes favour the development of fast-growing algae with adaptations to low light conditions. We studied algal and cyanobacterial colonization and succession in the nascent pl...

  20. Earthworm assemblages in different intensity of agricultural uses and their relation to edaphic variables

    OpenAIRE

    LB Falco; Sandler, R.; Momo, F; C Di Ciocco; Saravia, L; Coviella, C

    2015-01-01

    The objective of this study was to relate earthworm assemblage structure with three different soil use intensities, and to indentify the physical, chemical, and microbiological soil variables that are associated to the observed differences. Three soil uses were evaluated: 1-Fifty year old naturalized grasslands, low use intensity; 2-Recent agricultural fields, intermediate use intensity, and 3-Fifty year old intensive agricultural fields, high use intensity. Three different sites for each soi...

  1. Iterative Evolution of Sympatric Seacow (Dugongidae, Sirenia) Assemblages during the Past ∼26 Million Years

    OpenAIRE

    Velez-Juarbe, Jorge; Domning, Daryl P.; Pyenson, Nicholas D.

    2012-01-01

    Extant sirenians show allopatric distributions throughout most of their range. However, their fossil record shows evidence of multispecies communities throughout most of the past ∼26 million years, in different oceanic basins. Morphological differences among co-occurring sirenian taxa suggest that resource partitioning played a role in structuring these communities. We examined body size and ecomorphological differences (e.g., rostral deflection and tusk morphology) among sirenian assemblages...

  2. 'Domestic' origin of opaque assemblages in refractory inclusions in meteorites

    Science.gov (United States)

    Blum, Joel D.; Wasserburg, G. J.; Hutcheon, Ian D.; Beckett, John R.; Stolper, Edward M.

    1988-01-01

    Experimental studies indicate that opaque assemblages rich in refractory siderophile elements were formed within host calcium- and aluminum-rich inclusions (CAIs) by exsolution, oxidation and sulphidization of homogeneous alloys, rather than by aggregation of materials in the solar nebula before the formation of CAIs. These opaque assemblages are thus not the oldest known solid materials, as was once thought, and they do not constrain processes in the early solar nebula before CAI formation. Instead, the assemblages record the changing oxygen fugacity experienced by CAIs during slow cooling in nebular and/or planetary environments.

  3. Flow of Fluid and Particle Assemblages in Rotating Systems

    Science.gov (United States)

    Kizito, John; Hiltner, David; Niederhaus, Charles; Kleis, Stanley; Hudson, Ed; Gonda, Steve

    2004-01-01

    NASA-designed bioreactors have been highly successful in growing three-dimensional tissue structures in a low shear environment both on earth and in space. The goal of the present study is to characterize the fluid flow environment within the HFB-S bioreactor and determine the spatial distribution of particles that mimic cellular tissue structures. The results will be used to obtain optimal operating conditions of rotation rates and media perfusehnfuse rates which are required for cell culture growth protocols. Two types of experiments have been performed so far. First, we have performed laser florescent dye visualization of the perfusion loop to determine the mixing times within the chamber. The second type of experiments involved particles which represent cellular tissue to determine the spatial distribution with the chamber. From these experiments we established that mixing times were largely dependant on the speed ratio and sign of the difference between the spinner and the dome. The shortest mixing times occurred when the spinner rotates faster than the dome and longest mixing times occurs with no relative motion between the dome and spinner. Also, we have determined the spatial and temporal distribution of particle assemblages within the chamber.

  4. Field tests of interspecific competition in ant assemblages: revisiting the dominant red wood ants.

    Science.gov (United States)

    Gibb, Heloise; Johansson, Therese

    2011-05-01

    1. There has been considerable debate on the importance of competition in ecological communities, but its importance in structuring ant assemblages has often been uncritically accepted. Here, we briefly review field experiments examining competition in ant assemblages and use a removal experiment to test the effect of the classical territorial dominant ant, Formica aquilonia. Ants of this species group are thought to structure communities through a dominance hierarchy. 2. First, we used pitfall traps to compare the abundance of other ants in replicated sites with low and high densities of F. aquilonia. We found differences in community composition, in particular, Camponotus herculeanus was more common in low-density sites, in accordance with predictions. Differences in ant assemblages were not owing to differences in measured habitat variables. 3. We removed F. aquilonia from a set of high-density sites, using physical and chemical methods, and repeated these procedures at procedural control sites. One year after removal, abundances of F. aquilonia at removal sites were similar to those at low-density sites. However, the composition of other species did not change in response to F. aquilonia removal. Replication rates were identical in the mensurative and experimental components of this study, so this is unlikely to be owing to the analysis being insufficiently powerful. 4. We suggest three possibilities for the lack of difference. First, the study may have been too short term or small scale to detect differences. However, previous studies have shown effects on smaller spatial- and temporal-scales. Second, priority effects may be important in the successful colonisation by F. aquilonia. Thirdly, boreal ant assemblages may be too depauperate for redundancy in ecological roles and for competition to play an important structuring role. 5. We thus recommend that long-term large-scale experiments be considered essential if we are to distinguish between competing

  5. Hydrographic processes driven by seasonal monsoon system affect siphonophore assemblages in tropical-subtropical waters (western North Pacific Ocean.

    Directory of Open Access Journals (Sweden)

    Wen-Tseng Lo

    Full Text Available This work is a part of the Taiwan Cooperative Oceanic Fisheries Investigation, the first large scale hydrographic and plankton survey around Taiwan (21-26°N, 119-123°E. The present study examined the influence of hydrodynamic and biological variables driven by monsoon system on the siphonophore assemblages through an annual cycle in 2004. Calycophorans, namely Chelophyes appendiculata, Diphyes chamissonis, Lensia subtiloides, Bassia bassensis, and Muggiaea atlantica, were the most dominant siphonophore species. Maximum abundance of these dominant species generally occurred during the warm period (May and August, while M. atlantica had a significantly peak abundance in February. Although no apparently temporal difference in siphonophore abundance was observed in the study, siphonophore assemblage was more diverse in August than in other sampling times. Result of a cluster analysis indicated that assemblage structure of siphonophores in the waters around Taiwan varied at temporal and spatial scales during the sampling period. The intrusions of the Kuroshio Branch Current and China Coastal Current to the study area play an important role on the transportation of siphonophores. Also, the distribution of siphonophore assemblage was closely related to the hydrographic characteristics, with temperature, chlorophyll a concentration, and zooplankton abundance being the major environmental factors affecting the spatio-temporal variability of siphonophores. This study contributes substantially to the new knowledge of the siphonophore assemblage in the tropical-temperate waters of Taiwan.

  6. Mesophotic reef fish assemblages of the remote St. Peter and St. Paul's Archipelago, Mid-Atlantic Ridge, Brazil

    Science.gov (United States)

    Rosa, Marcos Rogerio; Alves, Aline Cristina; Medeiros, Diego Valverde; Coni, Ericka Oliveira Cavalcanti; Ferreira, Camilo Moitinho; Ferreira, Beatrice Padovani; de Souza Rosa, Ricardo; Amado-Filho, Gilberto Menezes; Pereira-Filho, Guilherme Henrique; de Moura, Rodrigo Leão; Thompson, Fabiano Lopes; Sumida, Paulo Yukio Gomes; Francini-Filho, Ronaldo Bastos

    2016-03-01

    Mesophotic reef fish assemblages (30-90 m depth) of the small and remote St. Peter and St. Paul's Archipelago (SPSPA), Mid-Atlantic Ridge, Brazil, were characterized using remotely operated vehicles. Ordination analyses identified distinct fish assemblages in the upper (30-50 m) and lower (50-90 m) mesophotic zones, the former characterized by high abundances of species that are also abundant at euphotic reefs ( Caranx lugubris, Melichthys niger, Stegastes sanctipauli and Chromis multilineata) and the latter dominated by two mesophotic specialists ( Prognathodes obliquus and Chromis enchrysura). Planktivores dominated fish assemblages, particularly in the upper mesophotic zone, possibly due to a greater availability of zooplankton coming from the colder Equatorial Undercurrent in mesophotic depths of the SPSPA. Turf algae, fleshy macroalgae and scleractinian corals dominated benthic assemblages between 30 and 40 m depth, while bryozoans, black corals and sponges dominated between 40 and 90 m depth. Canonical correspondence analysis explained 74 % of the relationship between environmental characteristics (depth, benthic cover and complexity) and structure of fish assemblages, with depth as the most important independent variable. Juveniles of Bodianus insularis and adults of P. obliquus and C. enchrysura were clearly associated with branching black corals ( Tanacetipathes spp.), suggesting that black corals play key ecological roles in lower mesophotic reefs of the SPSPA. Results from this study add to the global database about mesophotic reef ecosystems (MREs) and provide a baseline for future evaluations of possible anthropogenic and natural disturbances on MREs of the SPSPA.

  7. Climate extremes can drive biological assemblages to early successional stages compared to several mild disturbances.

    Science.gov (United States)

    Sanz-Lázaro, Carlos

    2016-01-01

    Extreme climatic events have a major role in the structuring of biological communities, and their occurrence is expected to increase due to climate change. Here I use a manipulative approach to test the effects of extreme storm events on rocky mid-shore assemblages. This study shows that an extreme storm can cause more negative effects than several mild storms, primarily by bringing the biological assemblages towards early stages of succession. This finding contrasts with the effects of clustering of climatic events due to climate change, which are expected to mitigate its ecological impacts. Thus, the ecological consequences of climatic events that are influenced by climate change may have contrasting effects depending on the features that are considered. These results have relevant implications in the forecasting of the ecological consequences of climate change and should be considered when designing measures to mitigate its effects. PMID:27527612

  8. Initial stresses in two-layer metal domes due to imperfections of their production and assemblage

    Directory of Open Access Journals (Sweden)

    Lebed Evgeniy Vasil’evich

    2015-04-01

    Full Text Available The process of construction of two-layer metal domes is analyzed to illustrate the causes of initial stresses in the bars of their frames. It has been noticed that it is impossible to build such structures with ideal geometric parameters because of imperfections caused by objective reasons. These imperfections cause difficulties in the process of connection of the elements in the joints. The paper demonstrates the necessity of fitting operations during assemblage that involve force fitting and yield initial stresses due to imperfections. The authors propose a special method of computer modeling of enforced elimination of possible imperfections caused by assemblage process and further confirm the method by an analysis of a concrete metal dome.

  9. Habitat characteristics and environmental parameters influencing fish assemblages of karstic pools in southern Mexico

    Directory of Open Access Journals (Sweden)

    María Eugenia Vega-Cendejas

    2013-01-01

    Full Text Available Fish assemblage structure was evaluated and compared among 36 karstic pools located within protected areas of the Calakmul Biosphere Reserve (southern Mexico and unprotected adjacent areas beyond the Reserve. Nonmetric multidimensional scaling (MDS, indicator species analysis (ISA, and canonical correspondence analysis (CCA were used to identify which environmental factors reflected local influences and to evaluate the correlation of these variables with fish assemblages structure. Thirty-one species were encountered in these karstic pools, some for the first time within the Reserve. These aquatic environments were separated into three groups based on physico-chemical characteristics. Although CCA identified significant associations between several fish species (based on their relative abundance and environmental variables (K, NH4, NO3, and conductivity, the most abundant species (Astyanax aeneus, Poecilia mexicana, and Gambusia sexradiata occur in most pools and under several environmental conditions. Baseline data on fish diversity along with a continued monitoring program are essential in order to evaluate the conservation status of fish assemblages and their habitats, as well as to measure the influence of anthropogenic impacts on pristine habitats such as the karstic pools of the Calakmul Biosphere Reserve.

  10. Effects of anthropogenic impacts on benthic macroinvertebrates assemblages in subtropical mountain streams

    Directory of Open Access Journals (Sweden)

    Leticia M. Mesa

    2013-12-01

    Full Text Available The nature of the riparian and surrounding landscape has been modified by anthropogenic activities, which may subsequently alter the composition and functional structure of macroinvertebrate assemblages. The effect of these changes on function of benthic fauna is difficult to assess due to the scarce knowledge on functional structures in tropical streams. In this study we evaluate whether sites impacted and unimpacted by anthropogenic alterations differed in assemblage composition and density, richness and diversity of each functional feeding group. The selection of the sites was related to their distinct riparian characteristics, following the QBRy riparian quality index. Collector-gatherer was the dominant functional feeding group, comprising 91% of total density, whereas the proportion of shredders was very low, representing less of 0.5% of total density. Asemblage composition of macroinvertebrates differed between impacted and unimpacted sites. Predators were dominant in taxa number, representing about 60% of total taxa richness. In addition, the diversity and richness of collector-gatherers differed significantly between degraded and unimpacted sites, reflecting the sensitivity of this group to environmental changes and the utility to be used in the assessment of anthropogenic modifications. The results of this study reinforce the idea that riparian corridor management is critical for the distribution of macroinvertebrate assemblages as well as functional organization of lotic streams.

  11. Intertidal assemblage variation across a subtropical estuarine gradient: How good conceptual and empirical models are?

    Science.gov (United States)

    Morais, Gisele C.; Camargo, Maurício G.; Lana, Paulo

    2016-03-01

    Variation of intertidal macrobenthic structure at multiple spatial scales is still poorly known in tropical and subtropical estuaries. We have assessed the structural responses of intertidal benthic assemblages, expressed by variation in number of species, abundance and assemblage composition, to key environmental drivers in a subtropical estuary from southern Brazil. We have applied a hierarchical sampling design to assess benthic variation at each of several spatial scales, from meters to kilometers, along a marked estuarine gradient. The hypothesis that many benthic variables vary at the largest spatial scale, corresponding to the salinity gradient, was refuted for number of species but not for total abundance and species composition. However, physiological stress to salinity variation, an important environmental driver in estuaries, could not explain by itself macrobenthic distribution along local intertidal flats. Nutrient, organic matter, photosynthetic pigments contents, pH, grain size, silt-clay content and the redox discontinuity layer also varied at the largest spatial scale acting as confounding factors. Thus, overall distribution patterns of intertidal benthic assemblages resulted from a complex interaction among environmental drivers, including salinity.

  12. How complementary are epibenthic assemblages in artificial and nearby natural rocky reefs?

    KAUST Repository

    Carvalho, Susana

    2013-12-01

    The present study analyses the composition, structure and trophic function of epibenthic assemblages in two artificial reefs (ARs) 16 years after deployment and in nearby natural reefs (NRs), aiming at providing insights on the complementarity between both habitats. Current findings suggest that after 16 years the ARs (concrete blocks), located in southern Portugal, do not act as surrogates for NRs, as epibenthic assemblages differed between reef types in composition, structure and trophic function. NRs showed higher diversity and complementarity (i.e. beta-diversity) than ARs, evidencing higher redundancy. Higher heterogeneity within NRs was also evidenced by the multi-dimensional scaling analysis based on abundance, biomass and trophic composition. NRs presented higher abundance of molluscs and biomass of sponges, resulting in differences in the trophic function: suspension-feeding dominated the NRs, while within ARs there was an ascendency of carnivory. Although not acting as surrogates for NRs and provided that no adverse effects (e.g. establishment of non-native species) were detected, ARs may have a significant contribution for the increase of regional diversity, as evidenced by the highest complementarity levels observed between assemblages in both reefs. © 2013 Elsevier Ltd.

  13. Assemblage of the vertical: commercial drones and algorithmic life

    OpenAIRE

    Crampton, Jeremy W.

    2016-01-01

    This paper takes up the increasingly popular topic of drones – including unmanned aerial vehicles (UAVs), small unmanned aerial systems (sUAS), remotely piloted aircraft (RPA), and a vast panoply of commercial drones and copters – to argue that our analysis should lie not so much on drones as objects, but as assemblages of the vertical. Drones, I argue, constitute a socio-technical assemblage of the sky and vertical space, which means that our focus should be not (only) on thei...

  14. Assemblage time series reveal biodiversity change but not systematic loss

    OpenAIRE

    Dornelas, Maria; Nicholas J. Gotelli; McGill, Brian; Shimadzu, Hideyasu; Moyes, Faye; Sievers, Caya; Magurran, Anne E.

    2014-01-01

    The extent to which biodiversity change in local assemblages contributes to global biodiversity loss is poorly understood. We analyzed 100 time series from biomes across Earth to ask how diversity within assemblages is changing through time. We quantified patterns of temporal α diversity, measured as change in local diversity, and temporal β diversity, measured as change in community composition. Contrary to our expectations, we did not detect systematic loss of α diversity. However, communit...

  15. Spatial patterns of ectomycorrhizal assemblages in a monospecific forest in relation to host tree genotype.

    Science.gov (United States)

    Lang, Christa; Finkeldey, Reiner; Polle, Andrea

    2013-01-01

    Ectomycorrhizas (EcM) are important for soil exploration and thereby may shape belowground interactions of roots. We investigated the composition and spatial structures of EcM assemblages in relation to host genotype in an old-growth, monospecific beech (Fagus sylvatica) forest. We hypothesized that neighboring roots of different beech individuals are colonized by similar EcM assemblages if host genotype had no influence on the fungal colonization and that the similarity would decrease with increasing distance of the sampling points. The alternative was that the EcM species showed preferences for distinct beech genotypes resulting in intraspecific variation of EcM-host assemblages. EcM species identities, abundance and exploration type as well as the genotypes of the colonized roots were determined in each sampling unit of a 1 L soil core (r = 0.04 m, depth 0.2 m). The Morisita-Horn similarity indices (MHSI) based on EcM species abundance and multiple community comparisons were calculated. No pronounced variation of MHSI with increasing distances of the sampling points within a plot was found, but variations between plots. Very high similarities and no between plot variation were found for MHSI based on EcM exploration types suggesting homogenous soil foraging in this ecosystem. The EcM community on different root genotypes in the same soil core exhibited high similarity, whereas the EcM communities on the root of the same tree genotype in different soil cores were significantly dissimilar. This finding suggests that spatial structuring of EcM assemblages occurs within the root system of an individual. This may constitute a novel, yet unknown mechanism ensuring colonization by a diverse EcM community of the roots of a given host individual. PMID:23630537

  16. Short-term responses of reptile assemblages to fire in native and weedy tropical savannah

    Directory of Open Access Journals (Sweden)

    Rickard Abom

    2016-04-01

    Full Text Available Fire is frequently used as a management tool to reduce the cover of weeds, to reduce the amount of fuel available for future fires, and to create succession mosaics that may enhance biodiversity. We determined the influence of fire on wildlife, by quantifying reptile assemblage composition in response to fire in a weedy environment characterised by very short-term fire return intervals (<2 years. We used reptiles because they are often understudied, and are only moderately vagile compared to other vertebrates, and they respond strongly to changes in vegetation structure. We repeatedly sampled 24 replicate sampling sites after they had been unburned for two years, just prior to burning (pre-burnt, just after burning (post-burnt, and up to 15 months after burning (revegetated and monitored vegetation structure and reptile richness, abundance and assemblage composition. Our sites were not spatially auto-correlated, and were covered by native kangaroo grass (Themeda triandra, black spear grass (Heteropogon contortus, or an invasive weed (grader grass, Themeda quadrivalvis. Reptile abundance and richness were highest when sites had been unburned for 2 years, and greatly reduced in all areas post burning. The lowest reptile abundances occurred in sites dominated by the weed. Reptile abundance and richness had recovered in all grass types 15 months after burning, but assemblage composition changed. Some species were present only in before our focus fire in native grass, and their populations did not recover even 15 months post-burning. Even in fire-prone, often-burnt habitats such as our study sites, in which faunal richness and abundance were not strongly influenced by fire, reptile assemblage composition was altered. To maintain faunal biodiversity in fire-prone systems, we suggest reducing the frequency of prescribed fires, and (if possible excluding fire from weedy invasions if it allows native grasses to return.

  17. Diversity and composition of estuarine and lagoonal fish assemblages of Socotra Island, Yemen.

    Science.gov (United States)

    Lavergne, E; Zajonz, U; Krupp, F; Naseeb, F; Aideed, M S

    2016-05-01

    Estuarine and lagoonal surveys of Socotra Island and selected sites on the Hadhramout coast of Yemen were conducted with the objective of documenting and analysing fish diversity and assemblage structure. A total of 74 species in 35 families were recorded, among which 65 species in 32 families were from Socotra and 20 species in 17 families were from mainland Yemen. Twenty-one species represent new faunal records for Socotra. Including historic records re-examined in this study, the total fish species richness of estuaries and lagoons of Socotra Island reaches 76, which is relatively high compared to species inventories of well-researched coastal estuaries in southern Africa. Five species dominate the occurrence and abundance frequencies: Terapon jarbua, Hyporhamphus sindensis, Aphanius dispar, Ambassis gymnocephala and Chelon macrolepis. Rarefaction and extrapolation analyses suggest that the actual number of fish species inhabiting some of those estuaries might be higher than the one observed. Thus, additional sampling at specific sites should be conducted to record other less conspicuous species. Ordination and multivariate analyses identified four main distinct assemblage clusters. Two groups are geographically well structured and represent northern Socotra and mainland Yemen, respectively. The other two assemblage groups tend to be determined to a greater extent by the synchrony between physical (e.g. estuary opening periods) and biological (e.g. spawning and recruitment periods) variables than by geographical location. Finally, the single intertidal lagoon of Socotra represents by itself a specific fish assemblage. The high proportion of economically important fish species (38) recorded underscores the paramount importance of these coastal water bodies as nursery sites, and for sustaining vital provisioning ecosystem services. PMID:27170111

  18. Large-scale assessment of Mediterranean marine protected areas effects on fish assemblages.

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    Paolo Guidetti

    Full Text Available Marine protected areas (MPAs were acknowledged globally as effective tools to mitigate the threats to oceans caused by fishing. Several studies assessed the effectiveness of individual MPAs in protecting fish assemblages, but regional assessments of multiple MPAs are scarce. Moreover, empirical evidence on the role of MPAs in contrasting the propagation of non-indigenous-species (NIS and thermophilic species (ThS is missing. We simultaneously investigated here the role of MPAs in reversing the effects of overfishing and in limiting the spread of NIS and ThS. The Mediterranean Sea was selected as study area as it is a region where 1 MPAs are numerous, 2 fishing has affected species and ecosystems, and 3 the arrival of NIS and the northward expansion of ThS took place. Fish surveys were done in well-enforced no-take MPAs (HP, partially-protected MPAs (IP and fished areas (F at 30 locations across the Mediterranean. Significantly higher fish biomass was found in HP compared to IP MPAs and F. Along a recovery trajectory from F to HP MPAs, IP were similar to F, showing that just well enforced MPAs triggers an effective recovery. Within HP MPAs, trophic structure of fish assemblages resembled a top-heavy biomass pyramid. Although the functional structure of fish assemblages was consistent among HP MPAs, species driving the recovery in HP MPAs differed among locations: this suggests that the recovery trajectories in HP MPAs are likely to be functionally similar (i.e., represented by predictable changes in trophic groups, especially fish predators, but the specific composition of the resulting assemblages may depend on local conditions. Our study did not show any effect of MPAs on NIS and ThS. These results may help provide more robust expectations, at proper regional scale, about the effects of new MPAs that may be established in the Mediterranean Sea and other ecoregions worldwide.

  19. Pollinator-mediated assemblage processes in California wildflowers.

    Science.gov (United States)

    Briscoe Runquist, R; Grossenbacher, D; Porter, S; Kay, K; Smith, J

    2016-05-01

    Community assembly is the result of multiple ecological and evolutionary forces that influence species coexistence. For flowering plants, pollinators are often essential for plant reproduction and establishment, and pollinator-mediated interactions may influence plant community composition. Here, we use null models and community phylogenetic analyses of co-occurrence patterns to determine the role of pollinator-mediated processes in structuring plant communities dominated by congeners. We surveyed three species-rich genera (Limnanthes, Mimulus and Clarkia) with centres of diversity in the Sierra Nevada of California. Each genus contains species that co-flower and share pollinators, and each has a robust phylogeny. Within each genus, we surveyed 44-48 communities at three spatial scales, measured floral and vegetative traits and tested for segregation or aggregation of: (i) species, (ii) floral traits (which are likely to be influenced by pollinators), and (iii) vegetative traits (which are likely affected by other environmental factors). We detected both aggregation and segregation of floral traits that were uncorrelated with vegetative trait patterns; we infer that pollinators have shaped the community assembly although the mechanisms may be varied (competition, facilitation, or filtering). We also found that mating system differences may play an important role in allowing species co-occurrence. Together, it appears that pollinators influence community assemblage in these three clades. PMID:26864797

  20. Variations in the endemic fish assemblage of a global freshwater ecoregion: Associations with introduced species in cascading reservoirs

    Science.gov (United States)

    Daga, Vanessa S.; Gubiani, Éder A.

    2012-05-01

    The present study aimed at assessing spatial and temporal changes in the composition and structure of an endemic fish assemblage and the possible associations with introduces species in a system of cascading reservoirs, in Iguaçu River, state of Paraná, southern Brazil. We collected 135,639 specimens: 131,716 individuals of endemic species and 3923 of introduced species. The most abundant introduced species were: Odontesthes bonariensis (85.1%), Prochilodus lineatus (7.5%) and Tilapia rendalli (4.9%). Significant spatial and temporal differences in richness were observed for both endemic and introduced species. The composition and structure of the assemblage of endemic and introduced fish exhibited significant spatial differences. The Procrustes analysis showed a significant spatial association between composition and structure of the assemblage of endemic and introduced fish in Iguaçu River. Changes in the endemic fish assemblage of Iguaçu River related to the establishment of introduced species and to habitat changes caused by cascading reservoirs enable advancing knowledge on environmental impacts in freshwater ecoregions.

  1. Using helium and carbon(CO2)isotopes to distinguish between source and crustal contribution in arc magmas. A case study from the Lesser Antilles island arc

    International Nuclear Information System (INIS)

    A quantitative assessment of the fate of sediments at subduction zones is a vital component in understanding then cycling history between the mantle and the exosphere. Coupling helium isotope (3He/4He) investigations with a tracer of sediment type - such as carbon isotopes (13C)- offers the additional possibility of identifying the nature of the subducted sedimentary component (marine versus terrigenous sediments for example). A regional survey of the helium and carbon isotope geochemistry of the Lesser Antilles volcanic arc was undertaken. Both geothermal fluids (fumaroles and hot springs) and young phenocryst-bearing lavas were analysed to establish helium and carbon relations along the arc. The northern group of islands appears to be characterised by a mixture of MORB with subducted slab component while the southern group has a clear signature of crustal contamination: however in this case the CO2/3He ratios indicate a possible third component

  2. Philippe Chanson, La blessure du nom. Une anthropologie d’une séquelle de l’esclavage aux Antilles-Guyane

    OpenAIRE

    Coulmont, Baptiste

    2009-01-01

    Peu après l’abolition de l’esclavage français, en 1848, les affranchis des Antilles ont dû acquérir un état civil : ils n’avaient, auparavant, aucune identité fixe du point de vue de l’État. Une partie des patronymes reçus sont jugés, alors et aujourd’hui, ridicules ou blessants : Satan, Négrobar, Dément ou Comestible... Ce qui devait signifier l’entrée dans la citoyenneté devient signe héréditaire d’une origine servile. C’est cette « blessure » que l’anthropologue et théologien Philippe Chan...

  3. Pollution persistante des sols aux Antilles par des insecticides organochlorés : HCH et chlordécone encore pour des siècles ?

    OpenAIRE

    Cabidoche, Yves-Marie; Cattan, Philippe; Clermont-Dauphin, Claridge; Gaspard, Sarra; Lesueur-Jannoyer, Magalie; Loranger-Merciris, Gladys

    2009-01-01

    La lutte contre le charançon du bananier, Cosmopolites sordidus, s’est longuement appuyée sur des insecticides organochlorés aux Antilles françaises à la fin du siècle dernier : - l’hexachlorocyclohexane (HCH), dont seul l’isomère γ est insecticide, a été appliqué à des doses massives, jusqu’à plus de 300 kg/ha/an d’HCH « technique » (mélange de 5 isomères dont 20% de γ), dans les années 60 à 70 ; - la chlordécone (CLD), appliquée à 3 kg de matière active (MA)/ha/an, par les insecticides US «...

  4. Differential assemblage of functional units in paddy soil microbiomes.

    Science.gov (United States)

    Kim, Yongkyu; Liesack, Werner

    2015-01-01

    Flooded rice fields are not only a global food source but also a major biogenic source of atmospheric methane. Using metatranscriptomics, we comparatively explored structural and functional succession of paddy soil microbiomes in the oxic surface layer and anoxic bulk soil. Cyanobacteria, Fungi, Xanthomonadales, Myxococcales, and Methylococcales were the most abundant and metabolically active groups in the oxic zone, while Clostridia, Actinobacteria, Geobacter, Anaeromyxobacter, Anaerolineae, and methanogenic archaea dominated the anoxic zone. The protein synthesis potential of these groups was about 75% and 50% of the entire community capacity, respectively. Their structure-function relationships in microbiome succession were revealed by classifying the protein-coding transcripts into core, non-core, and taxon-specific transcripts based on homologous gene distribution. The differential expression of core transcripts between the two microbiomes indicated that structural succession is primarily governed by the cellular ability to adapt to the given oxygen condition, involving oxidative stress, nitrogen/phosphorus metabolism, and fermentation. By contrast, the non-core transcripts were expressed from genes involved in the metabolism of various carbon sources. Among those, taxon-specific transcripts revealed highly specialized roles of the dominant groups in community-wide functioning. For instance, taxon-specific transcripts involved in photosynthesis and methane oxidation were a characteristic of the oxic zone, while those related to methane production and aromatic compound degradation were specific to the anoxic zone. Degradation of organic matters, antibiotics resistance, and secondary metabolite production were detected to be expressed in both the oxic and anoxic zones, but by different taxonomic groups. Cross-feeding of methanol between members of the Methylococcales and Xanthomonadales was suggested by the observation that in the oxic zone, they both

  5. Differential assemblage of functional units in paddy soil microbiomes.

    Directory of Open Access Journals (Sweden)

    Yongkyu Kim

    Full Text Available Flooded rice fields are not only a global food source but also a major biogenic source of atmospheric methane. Using metatranscriptomics, we comparatively explored structural and functional succession of paddy soil microbiomes in the oxic surface layer and anoxic bulk soil. Cyanobacteria, Fungi, Xanthomonadales, Myxococcales, and Methylococcales were the most abundant and metabolically active groups in the oxic zone, while Clostridia, Actinobacteria, Geobacter, Anaeromyxobacter, Anaerolineae, and methanogenic archaea dominated the anoxic zone. The protein synthesis potential of these groups was about 75% and 50% of the entire community capacity, respectively. Their structure-function relationships in microbiome succession were revealed by classifying the protein-coding transcripts into core, non-core, and taxon-specific transcripts based on homologous gene distribution. The differential expression of core transcripts between the two microbiomes indicated that structural succession is primarily governed by the cellular ability to adapt to the given oxygen condition, involving oxidative stress, nitrogen/phosphorus metabolism, and fermentation. By contrast, the non-core transcripts were expressed from genes involved in the metabolism of various carbon sources. Among those, taxon-specific transcripts revealed highly specialized roles of the dominant groups in community-wide functioning. For instance, taxon-specific transcripts involved in photosynthesis and methane oxidation were a characteristic of the oxic zone, while those related to methane production and aromatic compound degradation were specific to the anoxic zone. Degradation of organic matters, antibiotics resistance, and secondary metabolite production were detected to be expressed in both the oxic and anoxic zones, but by different taxonomic groups. Cross-feeding of methanol between members of the Methylococcales and Xanthomonadales was suggested by the observation that in the oxic zone

  6. The dark side of springs: what drives small-scale spatial patterns of subsurface meiofaunal assemblages?

    Directory of Open Access Journals (Sweden)

    Barbara Fiasca

    2014-02-01

    Full Text Available Springs are amongst the most relevant Groundwater Dependent Ecosystems (GDEs and are key research environments in freshwater ecology and biology. The strict dependency on ground water of surface spring biodiversity is well known, whereas the biodiversity occurring below the spring is very poorly known. This study analyzes copepod assemblages in the subsurface habitat of a karstic rheo-limnocrenic spring in relation to seventeen environmental parameters. Subsurface copepod assemblages were sensitive to microspatial variation in habitat structure, and species distributions were mostly driven by groundwater flowpath and substratum type, resulting in biologically distinct limnocrenic and rheocrenic sectors at the spring system scale. Habitat patchiness was reflected in differences in the microdistribution of subsurface copepods, stygobiotic assemblages being more sensitive to the measured environmental gradients than non-stygobiotic ones. In spite of the apparent stability of spring environments, copepods, as a target group, performed well as descriptors of sediment texture and hydrodynamics, and may offer relevant information for a better understanding of the potential changes generated by anthropogenic disturbance on these ecosystems..

  7. Termite assemblages in five semideciduous Atlantic Forest fragments in the northern coastland limit of the biome

    Directory of Open Access Journals (Sweden)

    Heitor Bruno de Araújo Souza

    2012-03-01

    Full Text Available Termites are abundant organisms in tropical ecosystems and strongly influence the litter decomposition and soil formation. Despite their importance, few studies about their assemblage structures have been made in Brazilian Atlantic Forest fragments, especially in the area located north of the São Francisco River. This study aims to analyze the assemblage composition of five Atlantic Forest fragments located in the northern biome limit along the Brazilian coast. A standardized sampling protocol of termites was applied in each fragment. Thirty-three termite species belonging to twenty genera and three families were found in the forest fragments. The wood-feeder group was dominant both concerning to species richness and number of encounters in all areas. In sites northern to 7°S, there is an evident simplification of the termite assemblage composition regarding species richness and number of encounters by feeding group. This fact is apparently due to a higher sandy level in soils and to semideciduous character of the vegetation in the northern fragments. Thus, even on the north of São Francisco River, termite biodiversity is heterogeneously spread with highest density of species in the portion between 07°S and São Francisco River mouth (10°29'S.

  8. Characteristics of the Mesophotic Megabenthic Assemblages of the Vercelli Seamount (North Tyrrhenian Sea)

    Science.gov (United States)

    Bo, Marzia; Bertolino, Marco; Borghini, Mireno; Castellano, Michela; Covazzi Harriague, Anabella; Di Camillo, Cristina Gioia; Gasparini, GianPietro; Misic, Cristina; Povero, Paolo; Pusceddu, Antonio; Schroeder, Katrin; Bavestrello, Giorgio

    2011-01-01

    The biodiversity of the megabenthic assemblages of the mesophotic zone of a Tyrrhenian seamount (Vercelli Seamount) is described using Remotely Operated Vehicle (ROV) video imaging from 100 m depth to the top of the mount around 61 m depth. This pinnacle hosts a rich coralligenous community characterized by three different assemblages: (i) the top shows a dense covering of the kelp Laminaria rodriguezii; (ii) the southern side biocoenosis is mainly dominated by the octocorals Paramuricea clavata and Eunicella cavolinii; while (iii) the northern side of the seamount assemblage is colonized by active filter-feeding organisms such as sponges (sometimes covering 100% of the surface) with numerous colonies of the ascidian Diazona violacea, and the polychaete Sabella pavonina. This study highlights, also for a Mediterranean seamount, the potential role of an isolated rocky peak penetrating the euphotic zone, to work as an aggregating structure, hosting abundant benthic communities dominated by suspension feeders, whose distribution may vary in accordance to the geomorphology of the area and the different local hydrodynamic conditions. PMID:21304906

  9. New Early Jurassic Tetrapod Assemblages Constrain Triassic-Jurassic Tetrapod Extinction Event

    Science.gov (United States)

    Olsen, P. E.; Shubin, N. H.; Anders, M. H.

    1987-08-01

    The discovery of the first definitively correlated earliest Jurassic (200 million years before present) tetrapod assemblage (Fundy basin, Newark Supergroup, Nova Scotia) allows reevaluation of the duration of the Triassic-Jurassic tetrapod extinction event. Present are tritheledont and mammal-like reptiles, prosauropod, theropod, and ornithischian dinosaurs, protosuchian and sphenosuchian crocodylomorphs, sphenodontids, and hybodont, semionotid, and palaeonisciform fishes. All of the families are known from Late Triassic and Jurassic strata from elsewhere; however, pollen and spore, radiometric, and geochemical correlation indicate an early Hettangian age for these assemblages. Because all ``typical Triassic'' forms are absent from these assemblages, most Triassic-Jurassic tetrapod extinctions occurred before this time and without the introduction of new families. As was previously suggested by studies of marine invertebrates, this pattern is consistent with a global extinction event at the Triassic-Jurassic boundary. The Manicouagan impact structure of Quebec provides dates broadly compatible with the Triassic-Jurassic boundary and, following the impact theory of mass extinctions, may be implicated in the cause.

  10. Assessing fish assemblages similarity above and below a dam in a neotropical reservoir with partial blockage.

    Science.gov (United States)

    Araújo, F G; Santos, A B I; Albieri, R J

    2013-11-01

    Damming rivers disrupts the water flow and changes the ichthyofauna organisation. We investigated an impoundment with permanent connection and homogeneous environmental conditions between the zones above and below the dam. Temperature was comparatively higher during wet season irrespective of zone, and both zones had higher dissolved oxygen, conductivity and transparency in the dry season. A total of 1687 individuals comprising 27 species were collected in the downriver zone, while the reservoir had 879 individuals and 23 species. Each zone had different fish assemblage composition and structure, but assemblages were not explained by the examined environmental variables (r2 = 0.08; p = 0.307). Migratory species such as Pimelodus maculatus, Pimelodus fur, Leporinus copelandii and Prochilodus lineatus were the most affected, and probably are prevented to perform upriver migrations. On the other hand, lentic adapted species such as G. brasiliensis, Hoplias malabaricus and Hoplosternum littorale successfully colonised the reservoir. Therefore we conclude that the presence of the lateral hydrological connectivity alone does not guarantee the ecological connectivity since fish assemblage similarity differed between the two zones. Fish passage facilities should be monitored and managed to evaluate and improve their functionality. PMID:24789387

  11. Changes in soil microbial properties and nematode assemblage over time during rice cultivation

    Directory of Open Access Journals (Sweden)

    Yudi Liu

    2013-05-01

    Full Text Available The properties of red soil may change over time when paddy fields are developed on what was previously dry land. The effect of rice cultivation duration on soil invertebrates is unknown. Five chronosequences of rice cultivation (1, 10, 20, 50 and 100 years were selected to investigate the temporal changes of soil microbiological properties and nematode assemblages. The results showed that soil microbial properties (microbial biomass C, microbial biomass N, basal respiration, nutrient availability (mineral N and P, nematode abundance and richness of nematode genera generally increased with the duration of rice cultivation. Notably, most soil measurements peaked after 50 years of cultivation (P<0.05 and decreased slightly after 100 years. As the period of rice cultivation increased, the proportion of nematode herbivores rose significantly (P < 0.05, while that of predators/omnivores slightly declined. Nematode Channel Ratio (NCR also increased with cultivation duration (P < 0.05, indicating that the bacterial energy channel was more dominant in old rice fields when compared to those cultivated for a shorter period. Other ecological indices of nematode assemblage such as maturity index and structure index, did not reveal consistent trends with an increased period of rice cultivation. In summary, a change in land use from dry land to paddy fields promotes soil microbial properties and nematode assemblages in the first few decades, which then become stable after 50 years of cultivation.

  12. Characteristics of the mesophotic megabenthic assemblages of the vercelli seamount (north tyrrhenian sea.

    Directory of Open Access Journals (Sweden)

    Marzia Bo

    Full Text Available The biodiversity of the megabenthic assemblages of the mesophotic zone of a Tyrrhenian seamount (Vercelli Seamount is described using Remotely Operated Vehicle (ROV video imaging from 100 m depth to the top of the mount around 61 m depth. This pinnacle hosts a rich coralligenous community characterized by three different assemblages: (i the top shows a dense covering of the kelp Laminaria rodriguezii; (ii the southern side biocoenosis is mainly dominated by the octocorals Paramuricea clavata and Eunicella cavolinii; while (iii the northern side of the seamount assemblage is colonized by active filter-feeding organisms such as sponges (sometimes covering 100% of the surface with numerous colonies of the ascidian Diazona violacea, and the polychaete Sabella pavonina. This study highlights, also for a Mediterranean seamount, the potential role of an isolated rocky peak penetrating the euphotic zone, to work as an aggregating structure, hosting abundant benthic communities dominated by suspension feeders, whose distribution may vary in accordance to the geomorphology of the area and the different local hydrodynamic conditions.

  13. Bait effects in sampling coral reef fish assemblages with stereo-BRUVs.

    Directory of Open Access Journals (Sweden)

    Stacey R Dorman

    Full Text Available Baited underwater video techniques are increasingly being utilised for assessing and monitoring demersal fishes because they are: 1 non extractive, 2 can be used to sample across multiple habitats and depths, 3 are cost effective, 4 sample a broader range of species than many other techniques, 5 and with greater statistical power. However, an examination of the literature demonstrates that a range of different bait types are being used. The use of different types of bait can create an additional source of variability in sampling programs. Coral reef fish assemblages at the Houtman Abrolhos Islands, Western Australia, were sampled using baited remote underwater stereo-video systems. One-hour stereo-video recordings were collected for four different bait treatments (pilchards, cat food, falafel mix and no bait (control from sites inside and outside a targeted fishery closure (TFC. In total, 5209 individuals from 132 fish species belonging to 41 families were recorded. There were significant differences in the fish assemblage structure and composition between baited and non-baited treatments (P<0.001, while no difference was observed with species richness. Samples baited with cat food and pilchards contained similar ingredients and were found to record similar components of the fish assemblage. There were no significant differences in the fish assemblages in areas open or closed to fishing, regardless of the bait used. Investigation of five targeted species indicated that the response to different types of bait was species-specific. For example, the relative abundance of Pagrus auratus was found to increase in areas protected from fishing, but only in samples baited with pilchards and cat food. The results indicate that the use of bait in conjunction with stereo-BRUVs is advantageous. On balance, the use of pilchards as a standardised bait for stereo-BRUVs deployments is justified for use along the mid-west coast of Western Australia.

  14. Bathymetric and regional changes in benthic macrofaunal assemblages on the deep Eastern Brazilian margin, SW Atlantic

    Science.gov (United States)

    Bernardino, Angelo Fraga; Berenguer, Vanessa; Ribeiro-Ferreira, Venina P.

    2016-05-01

    Deep-sea continental slopes have valuable mineral and biological resources in close proximity to diverse, undersampled and fragile marine benthic ecosystems. The eastern Brazilian Continental Margin (19.01°S to 21.06°S, 37.88°W to 40.22°W) is an important economic region for both fishing and oil industries, but is poorly understood with respect to the structure of the soft-sediment benthic fauna, their regional distribution and their bathymetric patterns. To identify spatial and temporal patterns of benthic macrofaunal assemblages on the slope (400 to 3000 m), the Espirito Santo Basin Assessment Project (AMBES, coordinated by Cenpes-Petrobras) sampled 42 stations across the Brazilian Eastern Slope during both Summer 2012 and Winter 2013. We found a significant decrease in macrofaunal abundance at the 400 m isobath along the slope near the northern region of the Espirito Santo Basin, suggesting benthic responses to upwelling events towards the south in Campos Basin and southern Espirito Santo Basin. The taxonomic diversity and assemblage composition also changed significantly across depth zones with mid-slope peaks of diversity at 1000-1300 m. In general, macrofaunal assemblages were strongly related to slope depth, suggesting a strong influence of productivity gradients and water mass distribution on this oligotrophic margin. Sediment grain size was marginally important to macrofaunal composition on the upper slope. In general, macrofaunal assemblages on the slope of Espirito Santo Basin are similar to other areas of the SE Brazilian margin, but regional changes in response to productivity and depth need to be considered for management strategies in the face of increasing economic activities off-shore.

  15. The impact of sediment removal on the aquatic macroinvertebrate assemblage in a fishpond littoral zone

    Directory of Open Access Journals (Sweden)

    Zdeněk ADÁMEK

    2011-02-01

    Full Text Available Bottom sediment removal, a widely used technique in restoration management of standing water bodies, has a strong influence on communities of aquatic organisms. As most information on the impact of sediment removal on the aquatic environment comes from studies on lakes, the aim of this study was to describe macroinvertebrate assemblage succession in a fishpond (Štěpánek fishpond, Bohemian-Moravian highlands, Czech Republic littoral zone following restoration by sediment removal during the winter of 2003/2004. Semi-quantitative hand net sampling was undertaken one year before (2003 and in each of the following five years (2004–2008 after sediment removal. A significant decrease in both abundance (approx. 90% of individuals and diversity (approx. 30% of taxa of macroinvertebrates was detected immediately after pond restoration. The values gradually increased over subsequent years, reaching comparable abundance and diversity three years after sediment removal. A significant shift was recorded in the taxonomic and functional composition of the macroinvertebrate assemblage after sediment removal. Mayfly larvae were the dominant invertebrates before restoration, while chironomid larvae and oligochaetes dominated after sediment removal. Phytophilous taxa, grazers and scrapers, and swimming or diving invertebrates were common in 2003, whilst open-water taxa preferring mud and other mostly inorganic microhabitats, gatherers/collectors, and burrowing/boring invertebrates were relatively common after sediment removal. In 2008, the assemblage reverted towards the situation before sediment removal, probably connected with a lower water level and accelerated macrophyte bed succession. Principal Component Analysis on the species data confirmed the differences in invertebrate taxonomic structure among sampling years. Succession of the fishpond invertebrate assemblage in the years following sediment removal was mainly influenced by fish farming practice and

  16. Fidelity of life and death molluscan assemblages from carbonate tidal flats in the Persian (Arabian) Gulf

    Science.gov (United States)

    García-Ramos, Diego A.; Albano, Paolo G.; Harzhauser, Mathias; Piller, Werner E.; Zuschin, Martin

    2016-04-01

    Live-dead (LD) studies aim to help understand how faithfully fossil assemblages can be used to quantitatively infer the structure of the original living communities that generated them. To this purpose, LD comparisons have been conducted in different terrestrial and aquatic environments to assess how environment-specific differences in quality and intensity of taphonomic factors affect LD fidelity. In sub-tropical and tropical settings, most LD studies have focused on hard substrates or seagrass bottoms. Here we present results on molluscan assemblages from soft carbonate sediments in tidal flats of the Persian (Arabian) Gulf (Indo-West Pacific biogeographic province). We analyzed a total of 7193 mollusks collected from six sites comprising time-averaged death assemblages (DAs) and snapshot living assemblages (LAs). All analyses were performed at site and at habitat scales after correcting for sample-size differences. We found a good match in proportional abundance and a notable mismatch in species composition. In fact, species richness in DAs is 6 times larger than in LAs at site scale, and 4 times at habitat scale. Additionally, we found a good fidelity of evenness, and rank abundance of feeding guilds. Other studies have shown that molluscan DAs from subtidal carbonate environments can display lower time-averaging than those from siliciclastic environments due to high rates of shell loss to bioerosion and dissolution. For our case study of tidal flat carbonate settings, we interpret that despite temporal autocorrelation (good fidelity of proportional abundance), substantial differences in species richness and composition can be explained by early cementation, lateral mixing, intense bioturbation and moderate sedimentation rates. Our results suggest that tidal flat carbonate environments can potentially lead to a wider window of time-averaging in comparison with subtidal carbonate settings.

  17. Assessing effects of stocked trout on nongame fish assemblages in southern Appalachian Mountain streams

    Science.gov (United States)

    Weaver, D.; Kwak, Thomas J.

    2013-01-01

    Fisheries managers are faced with the challenge of balancing the management of recreational fisheries with that of conserving native species and preserving ecological integrity. The negative effects that nonnative trout species exert on native trout are well documented and include alteration of competitive interactions, habitat use, and production. However, the effects that nonnative trout may exert on nongame fish assemblages are poorly understood. Our objectives were to quantify the effects of trout stocking on native nongame fish assemblages intensively on one newly stocked river, the North Toe River, North Carolina, and extensively on other southern Appalachian Mountain streams that are annually stocked with trout. In the intensive study, we adopted a before-after, control-impact (BACI) experimental design to detect short-term effects on the nongame fish assemblage and found no significant differences in fish density, species richness, species diversity, or fish microhabitat use associated with trout stocking. We observed differences in fish microhabitat use between years, however, which suggests there is a response to environmental changes, such as the flow regime, which influence available habitat. In the extensive study, we sampled paired stocked and unstocked stream reaches to detect long-term effects from trout stocking; however, we detected no differences in nongame fish density, species richness, species diversity, or population size structure between paired sites. Our results revealed high inherent system variation caused by natural and anthropogenic factors that appear to overwhelm any acute or chronic effect of stocked trout. Furthermore, hatchery-reared trout may be poor competitors in a natural setting and exert a minimal or undetectable impact on native fish assemblages in these streams. These findings provide quantitative results necessary to assist agencies in strategic planning and decision making associated with trout fisheries, stream

  18. Bat aggregation mediates the functional structure of ant assemblages.

    Science.gov (United States)

    Dejean, Alain; Groc, Sarah; Hérault, Bruno; Rodriguez-Pérez, Héctor; Touchard, Axel; Céréghino, Régis; Delabie, Jacques H C; Corbara, Bruno

    2015-10-01

    In the Guianese rainforest, we examined the impact of the presence of guano in and around a bat roosting site (a cave). We used ant communities as an indicator to evaluate this impact because they occupy a central place in the functioning of tropical rainforest ecosystems and they play different roles in the food web as they can be herbivores, generalists, scavengers or predators. The ant species richness around the cave did not differ from a control sample situated 500m away. Yet, the comparison of functional groups resulted in significantly greater numbers of detritivorous fungus-growing and predatory ant colonies around the cave compared to the control, the contrary being true for nectar and honeydew feeders. The role of bats, through their guano, was shown using stable isotope analyses as we noted significantly greater δ(15)N values for the ant species captured in and around the cave compared to controls. PMID:26302832

  19. The sulphur springs geothermal field, St. Lucia, lesser Antilles: Hydrothermal mineralogy of wells SL-1 and SL-2

    Science.gov (United States)

    Battaglia, S.; Gianelli, G.; Rossi, R.; Cavarretta, G.

    Two wells have been drilled to depths of 1413 and 2213 meters in the geothermal field of Sulphur Springs, St. Lucia, and reveal a complex volcanic sequence characterized by collapse episodes followed by the emplacement of dacite domes. The geothermal reservoir consists of fractured volcanic rocks and produces superheated steam. Well-bottom temperatures are around 270-290°C. The hydrothermal alteration found in both the productive SL-2 well and the non-productive SL-1 is strongly reminiscent of that of porphyry copper deposits, with (1) an inner, high-temperature potassic zone characterized by the occurrence of dravitic tourmaline, quartz, and biotite, (2) an outer propylitic alteration zone that is partly superimposed on (3) a potassic alteration zone. The alteration mineral assemblages indicate that the hydrothermal system has cooled at the levels sampled.

  20. Demersal fish assemblages off the Seine and Sedlo seamounts (northeast Atlantic)

    Science.gov (United States)

    Menezes, Gui M.; Rosa, Alexandra; Melo, Octávio; Pinho, Mário R.

    2009-12-01

    Seamounts are thought to support special biological communities, and often maintain high standing stocks of demersal and benthopelagic fishes. Seamount fish fauna have been described in several studies but few works have included species taken below 600 m. The demersal fish assemblages of the Seine and Sedlo seamounts (northeast Atlantic) from the summits to 2000 m depth were investigated based on longline survey catch data, conducted as part of the OASIS project. A total of 41 fish species from 24 families were caught at Seine near Madeira, and 30 species from 19 families were caught at Sedlo north of the Azores. Both fish faunas have high affinities with the neighbouring areas of the Azores, Madeira and with the eastern North Atlantic and the Mediterranean Sea. Overall abundances and mean body weights were slightly higher at Sedlo seamount, appearing in conformity with the latitudinal effect of increasing species abundance and productivity from south to north. The differential influence of the Mediterranean Water at each seamount may contribute to explain (a) the differences found in vertical distribution of common species, which tend to distribute deeper at Seine, and (b) the observed changes in the species composition and dominance in deeper waters. Multivariate analysis revealed a vertical structure that is approximately coincident with the expected zonation of water masses at each seamount. Physiological tolerance to the prevailing vertical hydrological conditions may explain the species distribution and the large-scale vertical assemblage structure found. However, further ecological factors like productivity patterns affecting the amount and quality of the available food appear to shape the abundance, diversity or dominance patterns of functional groups within those main assemblages. At Seine, the species Trachurus picturatus dominated the catches, mainly at the shallower edge of the plateau, appearing consistent with the sound-scattering layer interception

  1. Shaping up: a geometric morphometric approach to assemblage ecomorphology.

    Science.gov (United States)

    Bower, L M; Piller, K R

    2015-09-01

    This study adopts an ecomorphological approach to test the utility of body shape as a predictor of niche relationships among a stream fish assemblage of the Tickfaw River (Lake Pontchartrain Basin) in southeastern Louisiana, U.S.A. To examine the potential influence of evolutionary constraints, analyses were performed with and without the influence of phylogeny. Fish assemblages were sampled throughout the year, and ecological data (habitat and tropic guild) and body shape (geometric morphometric) data were collected for each fish specimen. Multivariate analyses were performed to examine relationships and differences between body shape and ecological data. Results indicate that a relationship exists between body shape and trophic guild as well as flow regime, but no significant correlation between body shape and substratum was found. Body shape was a reliable indicator of position within assemblage niche space. PMID:26268468

  2. Next generation sequencing reveals the hidden diversity of zooplankton assemblages.

    Directory of Open Access Journals (Sweden)

    Penelope K Lindeque

    Full Text Available BACKGROUND: Zooplankton play an important role in our oceans, in biogeochemical cycling and providing a food source for commercially important fish larvae. However, difficulties in correctly identifying zooplankton hinder our understanding of their roles in marine ecosystem functioning, and can prevent detection of long term changes in their community structure. The advent of massively parallel next generation sequencing technology allows DNA sequence data to be recovered directly from whole community samples. Here we assess the ability of such sequencing to quantify richness and diversity of a mixed zooplankton assemblage from a productive time series site in the Western English Channel. METHODOLOGY/PRINCIPLE FINDINGS: Plankton net hauls (200 µm were taken at the Western Channel Observatory station L4 in September 2010 and January 2011. These samples were analysed by microscopy and metagenetic analysis of the 18S nuclear small subunit ribosomal RNA gene using the 454 pyrosequencing platform. Following quality control a total of 419,041 sequences were obtained for all samples. The sequences clustered into 205 operational taxonomic units using a 97% similarity cut-off. Allocation of taxonomy by comparison with the National Centre for Biotechnology Information database identified 135 OTUs to species level, 11 to genus level and 1 to order, <2.5% of sequences were classified as unknowns. By comparison a skilled microscopic analyst was able to routinely enumerate only 58 taxonomic groups. CONCLUSIONS: Metagenetics reveals a previously hidden taxonomic richness, especially for Copepoda and hard-to-identify meroplankton such as Bivalvia, Gastropoda and Polychaeta. It also reveals rare species and parasites. We conclude that Next Generation Sequencing of 18S amplicons is a powerful tool for elucidating the true diversity and species richness of zooplankton communities. While this approach allows for broad diversity assessments of plankton it may

  3. Seasonal and Spatial Patterns of an Epibenthic Decapod Crustacean Assemblage in North-west Atlantic Continental Shelf Waters

    Science.gov (United States)

    Viscido, S. V.; Stearns, D. E.; Able, K. W.

    1997-09-01

    To examine seasonal and spatial patterns in a mobile marine assemblage, monthly samples were taken in triplicate with a 2-m beam trawl (6-mm mesh) at three separate stations (landward of the ridge, on the ridge top, and seaward of the ridge). The assemblage was of epibenthic decapod crustaceans, and was situated at a north-west Atlantic continental shelf, sandy ridge site. The assemblage was composed of nine species and was extremely variable over time and space. The sevenspine bay shrimp (Crangon septemspinosa), the Atlantic rock crab (Cancer irroratus), the spider crab (Libinia emarginata) and the lady crab (Ovalipes ocellatus) were the numerical dominants, comprising >98% of all decapods collected. Three of these species (C. septemspinosa,C. irroratus,L. emarginata) exhibited marked spatial heterogeneity in abundance, with many fewer found on the ridge top than at either of the other two stations.Ovalipes ocellatuswas not as spatially variable.Crangonshowed two clear peaks, in spring and fall, as didLibinia, but neither appeared to use the site as a nursery area.Ovalipes ocellatusandC. irroratuseach showed a single peak of very small individuals in the summer and appeared to use this site for settlement. Komolgorov-Smirnov tests, analysis of variance and cluster analysis showed much less difference in assemblage structure between the landward and seaward stations than was demonstrated between either station and the ridge top. The presence of the sand ridge had a clear impact on the abundance and distribution of local decapod crustacean populations.

  4. Draft genome sequencing of giardia intestinalis assemblage B isolate GS: is human giardiasis caused by two different species?

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    Oscar Franzén

    2009-08-01

    Full Text Available Giardia intestinalis is a major cause of diarrheal disease worldwide and two major Giardia genotypes, assemblages A and B, infect humans. The genome of assemblage A parasite WB was recently sequenced, and the structurally compact 11.7 Mbp genome contains simplified basic cellular machineries and metabolism. We here performed 454 sequencing to 16x coverage of the assemblage B isolate GS, the only Giardia isolate successfully used to experimentally infect animals and humans. The two genomes show 77% nucleotide and 78% amino-acid identity in protein coding regions. Comparative analysis identified 28 unique GS and 3 unique WB protein coding genes, and the variable surface protein (VSP repertoires of the two isolates are completely different. The promoters of several enzymes involved in the synthesis of the cyst-wall lack binding sites for encystation-specific transcription factors in GS. Several synteny-breaks were detected and verified. The tetraploid GS genome shows higher levels of overall allelic sequence polymorphism (0.5 versus <0.01% in WB. The genomic differences between WB and GS may explain some of the observed biological and clinical differences between the two isolates, and it suggests that assemblage A and B Giardia can be two different species.

  5. Elk herbivory alters small mammal assemblages in high elevation drainages

    Science.gov (United States)

    Parsons, Elliott W.R.; Maron, John L.; Martin, Thomas E.

    2012-01-01

    Heavy herbivory by ungulates can substantially alter habitat, but the indirect consequences of habitat modification for animal assemblages that rely on that habitat are not well studied. This is a particularly important topic given that climate change can alter plant–herbivore interactions.

  6. Temporal variability in epifaunal assemblages associated with temperate gorgonian gardens

    KAUST Repository

    Dias, I.M.

    2015-10-19

    The present study is one of the few that investigate the temporal variability of epifaunal assemblages associated with coral species, particularly the octocorals Eunicella gazella and Leptogorgia lusitanica in south Portugal. The results suggest time rather than colony size as a primary driver of the ecological patterns of these assemblages, which were dominated by amphipods, molluscs and polychaetes. Temporal variability was linked to changes in environmental parameters, namely temperature, chlorophyll a and particulate organic carbon. Hence, temporal variability must be taken into account for the design of future biodiversity assessment studies, as different patterns may be observed depending on the sampling time. Associated epifaunal assemblages were consistently dominated by resident species (i.e. species present in all sampling periods) and a peak of rare species was observed in the transition from spring to summer following the increase of seawater temperature. Turnover was particularly high in the transition between the spring and summer periods. In both hosts, turnover was higher in the small sized colonies, which generally harboured less diverse and less abundant assemblages which also differed from those inhabiting larger size colonies. The high levels of diversity associated with gorgonian colonies highlights the need for the conservation of this priority habitat.

  7. Bacterial assemblages in rivers and billabongs of Southeastern Australia.

    Science.gov (United States)

    Boon, P I

    1991-12-01

    Billabongs, lentic waterbodies common to the floodplain of Australian rivers, differ considerably from the lotic riverine environment in terms of hydrology, physiochemical characteristics, and biological assemblages present. As little is known regarding the bacterial ecology of billabong habitats, a comparison was made of the bacterial assemblages in the water column of seven paired river/billabong sites in the Murray-Darling Basin of southeastern Australia. Billabongs supported larger populations of bacteria (1-157×10(9) cells liter(-1); 11-10,270 μg C liter(-1)) than did rivers (1-10×10(9) cells liter(-1); 6-143 μg C liter(-1)). Phospholipid analyses confirmed that billabongs (14-111 μg phospholipid fatty acid liter(-1)) had larger bacterial populations than rivers (billabongs (0.28-3.05 μg C liter(-1) hour(-1)) than rivers (0.05-0.62 μg C liter(-1) hour(-1)). Production calculated from the frequency of dividing cells confirmed this conclusion, and suggested bacterial production in some billabongs could exceed 100 μg C liter(-1) hour(-1). An INT-formazan method indicated that usually billabongs, and the cell-specific activity greater for billabong than river assemblages. The factors most likely to be responsible for the differences between the bacterial assemblages in rivers and billabongs relate to hydrological regime and the availability of organic carbon substrates. PMID:24194324

  8. The assemblage of compliance in psychiatric case management.

    Science.gov (United States)

    Brodwin, Paul

    2010-08-01

    In the post-asylum era, case managers perform much of the face-to-face work of pharmaceutical compliance for people with severe and persistent mental illness. Their work demands careful orchestration of the assemblage of compliance, including the actual medications, the ideology of biopsychiatry, the division of professional labor, and certain mundane tools. Ethnographic vignettes from an Assertive Community Treatment (ACT) team show how case managers use this assemblage in their everyday routines, but also how it undercuts key elements of the original ACT mission. Reflecting its roots in the deinstitutionalization movement, the ACT model gives case managers limitless responsibilities for clients' lives, but then narrowly defines their role as the prosthetic extension of psychiatric authority. To produce compliance, case managers depend on the medication cassette, analyzed here as a human/non-human hybrid woven into their ordinary work. The medication cassette has pre-scripted uses that enlist clinicians in biopsychiatric thinking and also silently impose compliant behavior on clients. The elements in the assemblage of compliance depend on each other, but they do not form a seamless whole, as evidenced by the dilemmas and micropolitics of the clinical front-line. Theoretical notions of assemblages and technologies of compliance, drawn from science and technology studies, illuminate a core conundrum of practice in psychiatric case management. PMID:20721752

  9. Shikarpur lithic assemblage: New questions regarding Rohri chert blade production

    Directory of Open Access Journals (Sweden)

    Charusmita Gadekar

    2014-03-01

    Full Text Available Recent excavations at Shikarpur, a fortified Harappan site situated near the Gulf of Kuchchh in Gujarat, Western India, brought to light a large collection of Rohri chert blades.  Chert found in the Rohri hill near Sukkur in Sindh, central Pakistan is distinctive and easily identifiable. The wide distribution of standardized Rohri chert blades is often regarded as a testimony to the Harappan efficiency in long distance trade and craft production.  The possibility of localized production of Rohri chert blades in Gujarat is often negated due to the constraints of raw-material availability.  The absence of Rohri chert working debitage from most of the sites in Gujarat, has lent support to this position. The Shikarpur Rohri blade assemblage however incorporates more than 650 blades, a large fluted blade-core and a few Rohri chert debitage.  These have led the excavators to suggest that some of the blades found at Shikarpur were locally produced from raw materials brought to the site from the Rohri hills.  Typo-technological features of the Rohri chert assemblage from Shikarpur have been analysed in this background. These along with metrical features of the assemblage are compared with Rohri chert assemblages from other major Harappan sites in the region to check the validity of the proposed ‘limited local production’.

  10. Relación entre características del hábitat y estructura del ensamble de insectos en humedales palustres urbanos del centro-sur de Chile Relationship between habitat characteristics and insect assemblage structure in urban freshwater marshes from central-south Chile

    Directory of Open Access Journals (Sweden)

    ROMINA VILLAGRÁN-MELLA

    2006-06-01

    los efectos de la urbanización sobre el funcionamiento de estos ecosistemas. Sin embargo, dada la falta de información biológica y taxonómica en especies de insectos asociados a humedales palustres, solo características del hábitat con efectos significativos a un nivel taxonómico alto podrían ser consideradas para establecer recomendaciones iniciales de planes de manejoWetlands are one of the most productive ecosystems which provide a number of ecosystem functions, maintaining also a high biodiversity. Nevertheless, almost half of the wetlands in the world have disappeared in the last century due to urban development process. Along the Chilean landscape a great variety of aquatic habitats exist. Due to urban expansion those ecosystems have been exposed to strong anthropogenic pressures. In the intercomunal area Concepción-Talcahuano- San Pedro (Biobío Region, more than 23 % (1,734 ha of the wetland areas have been lost in the last three decades. We evaluated the relationship between habitat characteristics (morphometric, limnology and vegetation and the insect assemblage's structure in seven freshwater marshes in this intercomunal area. Our aim was to assess the influence of urbanization on the diversity patterns of these ecosystems. Insect abundance and species diversity were positively correlated to matrix pristinness and oxygen concentration of the water, this last feature was the best predictor for the structure of the insect assemblage. Of the 24 insect morphospecies included in the analysis, the abundance of only seven species was significantly related to the quantified habitat characteristics. Matrix pristinness, wetland area, vegetation heterogeneity and water oxygen concentration were positively related to species abundance, however, conductivity and water density showed a negative effect on the abundance. The insect species diversity decrease determined by the habitat characteristics associated to habitat loss, habitat fragmentation, habitat

  11. Protection changes the relevancy of scales of variability in coralligenous assemblages

    Science.gov (United States)

    Piazzi, L.; La Manna, G.; Cecchi, E.; Serena, F.; Ceccherelli, G.

    2016-06-01

    The knowledge of natural spatial patterns of variability is crucial to discriminate between natural changes and human-induced effects and to plan monitoring programs and impact evaluation studies. The present study aimed at estimating the spatial variability of coralligenous habitat, one of the main important habitats of the Mediterranean Sea, at several spatial scales. Specifically, the following hypotheses were tested: i) the structure of coralligenous assemblage and ii) the abundance of main taxa/groups both changed among different spatial scales differently depending on protection. A hierarchical sampling design was used to study 14 localities (7 Marine Protected Areas and 7 unprotected) at multiple spatial scales through photographic recording. The study suggested that, in protected conditions, the structure of coralligenous assemblages mostly varied at small spatial scale (m apart), while the structure is similar across different localities, sites and areas, even if the abundance of the main taxa/morphological groups changed. In unprotected conditions, variability among localities was higher than among Marine Protected Areas, while an opposite trend was observed at the smaller spatial scales.

  12. Influence of re-flooding on phytoplankton assemblages in a temperate wetland following prolonged drought

    Directory of Open Access Journals (Sweden)

    Luciana Avigliano

    2014-02-01

    Full Text Available Wetlands can experience drying and flooding cycles which influence the dynamics of the phytoplankton assemblages. The aim of our study was to evaluate changes in the phytoplankton structure during a drought/flood period in a warm-temperate wetland. We hypothesized that fluctuations in water level and development of macrophytes favour the development of fast-growing algae with adaptations to low light conditions. We studied algal and cyanobacterial colonization and succession in the nascent planktonic habitat in a wetland in the Southern Hemisphere (Argentina. We assessed changes in phytoplankton biovolume, chlorophyll a concentration (Chl a, richness, diversity, and evenness throughout a drought/flood period. Phytoplankton species were classified into ecological functional groups (FG. Multivariate analysis (RDA showed that water level, conductivity and percentage macrophyte cover of the site surface (PCSS explained the variability in the phytoplankton assemblage structure in terms of classes and FG. Particularly, FGs T and LM responded to the changes during the drought/flood cycle, probably due to light constraints and stability of the water column induced by the development of emergent and free-floating macrophytes. Our study expands the knowledge of phytoplankton species composition and ecological FG succession under free-floating macrophyte cover in a re-flooding episode. We conclude that water depth and development of macrophytes are the key factors in shaping phytoplankton species structure in a temporary wetland.

  13. Demersal Assemblages on the Soft Bottoms off the Catalan-Levante Coast of the Spanish Mediterranean

    Directory of Open Access Journals (Sweden)

    Mariano García-Rodríguez

    2011-01-01

    Full Text Available The analysis of 255 bottom trawl samples obtained in annual experimental surveys (2007–2010 along the western Mediterranean shows the existence of five well-defined demersal assemblages that follow a depth distribution: (a upper shelf assemblages, including two assemblages differentiated by the type of substrate (sand-muddy and terrigenous muddy bottoms; (b a middle shelf assemblage; (c an upper slope assemblage; (d a middle slope assemblage. Faunally, they are dominated by fish (37% of 452 total species, followed by crustaceans (22%, molluscs (17%, echinoderms (9%, and other invertebrates (15%. The assemblages identified showed major alterations on the shelf and shelf edge and less pronounced ones on the upper and middle slope. The average diversity values were more or less high, evidencing the high species richness in the western Mediterranean. The identified assemblages may facilitate future multispecies fisheries management based on an ecosystem approach.

  14. Climate and elevational range of a South African dragonfly assemblage

    Directory of Open Access Journals (Sweden)

    Michael Samways

    2010-12-01

    Full Text Available Elevation and climate are interrelated variables which have a profound affect on biota. Flying insects such as dragonflies can rapidly disperse and optimal habitat conditions at appropriate elevations. Such behaviour is likely to be especially important in geographical areas which are subject to major climatic events such as El Niño. Accordingly, we studied dragonflies and environmental variables in a series of reservoirs over an elevational range of 100–1350 m a.s.l. at the same latitude on the eastern seaboard of South Africa. The aim was to determine how elevation and climate (as regional processes, as well as local factors, influence species assemblage variability, habitat preference and phenology. Certain environmental variables strongly explained the main variation in species assemblage. These included local factors such as pH, marginal grasses, percentage shade, exposed rock, marginal forest and to a lesser extent, marshes and flow. Different species showed various tolerance levels to these variables. Elevation and climate as regional processes had very little influence on dragonfly assemblages in comparison with these environmental factors. These odonate species are essentially sub-tropical, and are similar to their tropical counterparts in that they have long flight periods with overlapping generations. Yet they also have temperate characteristics such as over-wintering mostly as larvae. These results indicate evolutionary adaptations from both temperate and tropical regions. Furthermore, most were also widespread and opportunistic habitat generalists. The national endemics Pseudagrion citricola and Africallagma sapphirinum only occurred at high elevations. However, the endemic Agriocnemis falcifera was throughout all elevations, suggesting regional endemism does not necessarily equate to elevational intolerance. Overall, the results suggest that many millennia of great climatic variation have led to a highly vagile and elevation

  15. Inter-annual species-level variations in an abyssal polychaete assemblage (Sta. M, NE Pacific, 4000 m)

    Science.gov (United States)

    Laguionie-Marchais, Claire; Paterson, Gordon L. J.; Bett, Brian J.; Smith, Kenneth L.; Ruhl, Henry A.

    2016-01-01

    Understanding the dynamics of abyssal community structure and function has become increasingly important as deep-sea resource exploitation and climate change pressures are expected to ramp up. This time-series study investigates macrofaunal polychaete dynamics at a station in the North East Pacific (Sta. M; 35° N 123° W, 4000 m, 1991-2011). Infaunal polychaete species were identified and their proxy biomass and proxy energy use rate estimated. The assemblage comprised 167 species, having a composition consistent with other abyssal areas globally. Significant changes in univariate and multivariate parameters (rank abundance distribution, Simpson's diversity index, and species and functional group composition) were detected across 1991-2011. However, no change in biomass or energy use rate was apparent through the time-series. The largest changes in the polychaete assemblage coincided with both an increase in sinking particulate organic carbon flux to the seafloor in 2007, and a 40 km relocation of the sampling location to a site 100 m shallower, preventing a conclusive assessment of which might drive the observed variation. Analyses prior to the change of sampling location showed that the polychaete assemblage composition dynamics were primary driven by food supply variation. Changes in several species were also lagged to changes in POC flux by 4-10 months. The polychaete fauna exhibited a significant positive relationship between total density and total energy use rate, suggesting population-level tracking of a common resource (e.g. POC flux food supply). Neither compensatory nor energetic zero-sum dynamics were detected among the polychaete assemblage, but the results suggest that the latter occur in the macrofaunal community as a whole. The results do indicate (a) potential control of species composition, and the density of individual key species, by food supply, when the time-series prior to the sampling location was analysed separately, and (b) generally

  16. Are intertidal soft sediment assemblages affected by repeated oil spill events? A field-based experimental approach.

    Science.gov (United States)

    Sandrini-Neto, Leonardo; Martins, César C; Lana, Paulo C

    2016-06-01

    This study investigates the impact of repeated diesel spills on the structure of intertidal macrofaunal assemblages of a subtropical estuary. Three frequencies of exposure events were compared against two dosages of oil in a factorial experiment with asymmetrical controls. Hypotheses were tested to distinguish between (i) the overall effect of oil spills, (ii) the effect of diesel dosage via different exposure regimes, and (iii) the effect of time since last spill. Repeated oil spills dramatically altered the overall structure of assemblages and reduced the total density of macrofauna and densities of dominant taxa. Increasing the frequency of oil spills negatively affected macrofauna. In general, frequent low-dosage oil spills were more deleterious than infrequent high-dosage ones. However, increases in densities of some taxa, mainly the gastropod Heleobia australis, were observed in response to infrequent spills. Our results highlight the importance of repeated exposure events in determining the extent of oil impacts. PMID:26890483

  17. Biodiversity of nematode assemblages from deep-sea sediments of the Atacama Slope and Trench (South Pacific Ocean)

    OpenAIRE

    Gambi, C.; Vanreusel, A.; Danovaro, R.

    2003-01-01

    Nematode assemblages were investigated (in terms of size spectra, sex ratio, Shannon diversity, trophic structure and diversity, rarefaction statistics, maturity index, taxonomic diversity and taxonomic distinctness) at bathyal and hadal depths (from 1050 to 7800 m) in the deepest trench of the South Pacific Ocean: the Trench of Atacama. This area, characterised by very high concentrations of nutritionally-rich organic matter also at 7800-m depth, displayed characteristics typical of eutrophi...

  18. Effects of land use intensification on fish assemblages in Mediterranean climate streams.

    Science.gov (United States)

    Matono, P; Sousa, D; Ilhéu, M

    2013-11-01

    Southern Portugal is experiencing a rapid change in land use due to the spread of intensive farming systems, namely olive production systems, which can cause strong negative environmental impacts and affect the ecological integrity of aquatic ecosystems. This study aimed to identify the main environmental disturbances related with olive grove intensification on Mediterranean-climate streams in southern Portugal, and to evaluate their effects on fish assemblage structure and integrity. Twenty-six stream sites within the direct influence of traditional, intensive, and hyper-intensive olive groves were sampled. Human-induced disturbances were analyzed along the olive grove intensity gradient. The integrity of fish assemblages was evaluated by comparison with an independent set of least disturbed reference sites, considering metrics and guilds, based on multivariate analyses. Along the gradient of olive grove intensification, the study observed overall increases in human disturbance variables and physicochemical parameters, especially organic/nutrient enrichment, sediment load, and riparian degradation. Animal load measured the impact of livestock production. This variable showed an opposite pattern, since traditional olive groves are often combined with high livestock production and are used as grazing pasture by the cattle, unlike more intensive olive groves. Stream sites influenced by olive groves were dominated by non-native and tolerant fish species, while reference sites presented higher fish richness, density and were mainly occupied by native and intolerant species. Fish assemblage structure in olive grove sites was significantly different from the reference set, although significant differences between olive grove types were not observed. Bray-Curtis similarities between olive grove sites and references showed a decreasing trend in fish assemblage integrity along the olive grove intensification gradient. Olive production, even in traditional groves, led to

  19. The effects of submarine canyons and the oxygen minimum zone on deep-sea fish assemblages off Hawai'i

    Science.gov (United States)

    De Leo, Fabio C.; Drazen, Jeffrey C.; Vetter, Eric W.; Rowden, Ashley A.; Smith, Craig R.

    2012-06-01

    Submarine canyons are reported to be sites of enhanced fish biomass and productivity on continental margins. However, little is known about the effects of canyons on fish biodiversity, in particular on oceanic islands, which are imbedded in regions of low productivity. Using submersibles and high-definition video surveys, we investigated demersal fish assemblages in two submarine canyons and slope areas off the island of Moloka'i, Hawai'i, at depths ranging from 314 to 1100 m. We addressed the interactions between the abundance, species richness and composition of the fish assemblage, and organic matter input and habitat heterogeneity, testing the hypotheses that heterogeneous bottom habitats and higher organic matter input in canyons enhance demersal fish abundance, and species density, richness and diversity, thereby driving differences in assemblage structure between canyons and slopes. Sediment type, substrate inclination, water-mass properties (temperature and dissolved oxygen) and organic matter input (modeled POC flux and percent detritus occurrence) were put into multivariate multiple regression models to identify potential drivers of fish assemblage structure. A total of 824 fish were recorded during ∼13 h of video yielding 55 putative species. Macrouridae was the most diverse family with 13 species, followed by Congridae (5), Ophidiidae (4) and Halosauridae (3). Assemblage structure changed markedly with depth, with the most abrupt change in species composition occurring between the shallowest stratum (314-480 m) and intermediate and deep strata (571-719 m, 946-1100 m). Chlorophthalmus sp. dominated the shallow stratum, macrourids and synaphobranchid eels at intermediate depths, and halosaurs in the deepest stratum. Assemblages only differed significantly between canyon and slope habitats for the shallow stratum, and the deep stratum at one site. Dissolved oxygen explained the greatest proportion of variance in the multivariate data, followed by POC

  20. Colwellia and sulfur-oxidizing bacteria: An unusual dual symbiosis in a Terua mussel (Mytilidae: Bathymodiolinae) from whale falls in the Antilles arc

    Science.gov (United States)

    Duperron, Sébastien; Gros, Olivier

    2016-09-01

    Seven individuals of a single morphotype of mussels (Bivalvia: Mytilidae) were found attached to a naturally sunken whale intervertebral disk collected in Guadeloupe (Caribbean) at 800 m depth. These specimens resemble small Idas mussels which are found worldwide at cold seeps and hydrothermal vents, and typically harbor ectosymbiotic bacteria on their gills upon which they depend for nutrition. Based on multi-locus gene sequencing, these specimens appear to belong to a new species closely related to two species now included within the genus Terua. Unexpectedly, its closest relatives are found in the Pacific, questioning how this species has reached the Antilles arc. Based on marker gene sequence analysis, electron and fluorescence microscopy, Terua n. sp. harbors two distinct and abundant extracellular bacterial symbionts located between microvilli at the apical surface of host gill epithelial cells. One is a sulfur-oxidizing bacterium similar to the symbionts previously identified in several deep-sea mussels, while the other is related to Colwellia species, a group of cold-adapted heterotrophic bacteria able to degrade organic compounds. This study provides the first evidence for the existence of a dual symbiosis in mussels from whale fall ecosystems in the Caribbean. The evolutionary history of Terua n. sp. and potential role of its Colwellia symbionts are discussed.

  1. Ectomycorrhizal fungal communities of Coccoloba uvifera (L.) L. mature trees and seedlings in the neotropical coastal forests of Guadeloupe (Lesser Antilles).

    Science.gov (United States)

    Séne, Seynabou; Avril, Raymond; Chaintreuil, Clémence; Geoffroy, Alexandre; Ndiaye, Cheikh; Diédhiou, Abdala Gamby; Sadio, Oumar; Courtecuisse, Régis; Sylla, Samba Ndao; Selosse, Marc-André; Bâ, Amadou

    2015-10-01

    We studied belowground and aboveground diversity and distribution of ectomycorrhizal (EM) fungal species colonizing Coccoloba uvifera (L.) L. (seagrape) mature trees and seedlings naturally regenerating in four littoral forests of the Guadeloupe island (Lesser Antilles). We collected 546 sporocarps, 49 sclerotia, and morphotyped 26,722 root tips from mature trees and seedlings. Seven EM fungal species only were recovered among sporocarps (Cantharellus cinnabarinus, Amanita arenicola, Russula cremeolilacina, Inocybe littoralis, Inocybe xerophytica, Melanogaster sp., and Scleroderma bermudense) and one EM fungal species from sclerotia (Cenococcum geophilum). After internal transcribed spacer (ITS) sequencing, the EM root tips fell into 15 EM fungal taxa including 14 basidiomycetes and 1 ascomycete identified. Sporocarp survey only weakly reflected belowground assessment of the EM fungal community, although 5 fruiting species were found on roots. Seagrape seedlings and mature trees had very similar communities of EM fungi, dominated by S. bermudense, R. cremeolilacina, and two Thelephoraceae: shared species represented 93 % of the taxonomic EM fungal diversity and 74 % of the sampled EM root tips. Furthermore, some significant differences were observed between the frequencies of EM fungal taxa on mature trees and seedlings. The EM fungal community composition also varied between the four investigated sites. We discuss the reasons for such a species-poor community and the possible role of common mycorrhizal networks linking seagrape seedlings and mature trees in regeneration of coastal forests. PMID:25711744

  2. Tsunami hazard assessment of Guadeloupe Island (F.W.I.) related to a megathrust rupture on the Lesser Antilles subduction interface

    Science.gov (United States)

    Roger, J.; Dudon, B.; Zahibo, N.

    2013-05-01

    The French Caribbean Archipelago of Guadeloupe is located over the Lesser Antilles active subduction zone, where a handful of earthquakes have reached magnitudes of Mw = 7.0 (moment magnitude) and more. According to available catalogs, these earthquakes have been able to trigger devastating tsunamis, either directly by the shake or indirectly by induced landslides. The Guadeloupe Archipelago is known to have suffered from several violent earthquakes, including the 1843 Mw ~ 8.5 megathrust event. In this study, we discuss the potential impact of a tsunami generation scenario of a Mw = 8.5 rupture at the subduction interface using numerical modeling and high resolution bathymetric data within the framework of tsunami hazard assessment for Guadeloupe. Despite the fact that the mystery remains unresolved concerning the lack of historical tsunami data for the 1843 event, modeling results show that the tsunami impact is not uniformly distributed in the whole archipelago and could show important maximum wave heights. This is easily explained by the bathymetry and the presence of several islands around the main island leading to resonance phenomena, and because of the existence of a fringing coral reef partially surrounding Guadeloupe Island and its satellites. We then discuss the role of source parameters, the arrival times and the protective role of fringing coral reefs surrounding the islands, using tsunami modeling applied on two Guadeloupian touristic coastal places: Sainte-Anne and Saint-François.

  3. Study of natural zircon-xenotime assemblages for estimation of the actinide waste forms stability

    International Nuclear Information System (INIS)

    In order to estimate compositions and structural stability of YPO4-ZrSiO4-USiO4-ThSiO4 solid solution, natural specimens of (U, Th)-enriched zircon-xenotime assemblages were studied. The samples were picked from granitic pegmatites of North Karelia of about 1,850 Ma age. TEM data show that amorphization of the zircon structure is not complete. Xenotime has typical crystal structure. ASEM and EPMA results indicate that zircon and xenotime are micro-heterogeneous in there compositions. Numerous micro-inclusions (3+ vs. Zr4+ and P5+ vs. Si4+). Data on high amounts of rare earth elements and phosphorus in natural zircons are result from REE-phosphate inclusions in analyzed zircons. Content of U in the zircon allowed the estimation of the solubility of coffinite end member to be no less than 5 mol.% USiO4

  4. Nestedness and successional trajectories of macroinvertebrate assemblages in man-made wetlands.

    Science.gov (United States)

    Ruhí, Albert; Boix, Dani; Gascón, Stéphanie; Sala, Jordi; Quintana, Xavier D

    2013-02-01

    Current successional models, primarily those based on floral succession, propose several distinct trajectories based on the integration of two key hypotheses from succession theory: convergence versus divergence in species composition among successional sites, and progression towards versus deviation from a desired reference state. We applied this framework to faunal succession, including differential colonization between active and passive dispersers, and the nested patterns generated as a consequence of this peculiarity. Nine man-made wetlands located in three different areas, from 0-3 years from wetland creation, were assessed. In addition, 91 wetlands distributed throughout the region were used as references for natural macroinvertebrate communities. We predicted the following: (1) highly nested structures in pioneering assemblages will decrease to lower mid-term values due to a shift from active pioneering taxa to passive disperser ones; (2) passive idiosyncratic taxa will elicit divergent successional trajectories among areas; (3) the divergent trajectories will provoke lower local and higher regional diversity values in the mid-term assemblages than in pioneer assemblages. Our results were largely congruent with hypotheses (1) and (2), diverging from the anticipated patterns only in the case of the temporary wetlands area. However, overall diversity trends based on hypothesis (3) did not follow the expected pattern. The divergent successional trajectories did not compensate for regional biodiversity losses that occurred as a consequence of pioneering colonizer decline over time. Consequently, we suggest reconsidering wetland construction for mitigation purposes within mid-term time frames (≤ 3 years). Wetlands may not offset, within this temporal scenario, regional biodiversity loss because the ecosystem may not support idiosyncratic taxa from natural wetlands. PMID:22965268

  5. Effects of competition and facilitation on species assemblage in two types of tropical cloud forest.

    Science.gov (United States)

    Long, Wenxing; Zang, Runguo; Ding, Yi; Huang, Yunfeng

    2013-01-01

    Competition and facilitation between tree individuals are two kinds of non-random processes influencing the structure and functioning of forest communities, but how these two plant-plant interactions change along gradient of resources or environments remains very much a matter of debate. We developed a null model to test the size-distance regression, and assessed the effects of competition and facilitation (including interspecific interactions, intraspecific interactions and overall species interactions) on each adult tree species assemblage [diameter at breast height (dbh) ≥5 cm] across two types of tropical cloud forest with different environmental and resource regimes. The null model test revealed that 17% to 27% tree species had positive dbh-distance correlations while 11% to 19% tree species showed negative dbh-distance correlations within these two forest types, indicating that both competition and facilitation processes existed during the community assembly. The importance of competition for heterospecific species, and the intensity of competition for both heterospecific and overall species increased from high to low resources for all the shared species spanning the two forests. The importance of facilitation for conspecific and overall species, as well as that the intensity of facilitation for both heterospecific and conspecific species increased with increasing low air temperature stress for all the shared species spanning the two forests. Our results show that both competition and facilitation processes simultaneously affect parts of species assemblage in the tropical cloud forests. Moreover, the fact that nearly 50% species assemblage is not detected with our approaches suggest that tree species in these tropical forest systems are assembled with multiple ecological processes, and that there is a need to explore the processes other than the two biotic interactions in further researches. PMID:23565209

  6. Taxonomic and Phylogenetic Determinants of Functional Composition of Bolivian Bat Assemblages.

    Directory of Open Access Journals (Sweden)

    Luis F Aguirre

    Full Text Available Understanding diversity patterns and the potential mechanisms driving them is a fundamental goal in ecology. Examination of different dimensions of biodiversity can provide insights into the relative importance of different processes acting upon biotas to shape communities. Unfortunately, patterns of diversity are still poorly understood in hyper-diverse tropical countries. Here, we assess spatial variation of taxonomic, functional and phylogenetic diversity of bat assemblages in one of the least studied Neotropical countries, Bolivia, and determine whether changes in biodiversity are explained by the replacement of species or functional groups, or by differences in richness (i.e., gain or loss of species or functional groups. Further, we evaluate the contribution of phylogenetic and taxonomic changes in the resulting patterns of functional diversity of bats. Using well-sampled assemblages from published studies we examine noctilionoid bats at ten study sites across five ecoregions in Bolivia. Bat assemblages differed from each other in all dimensions of biodiversity considered; however, diversity patterns for each dimension were likely structured by different mechanisms. Within ecoregions, differences were largely explained by species richness, suggesting that the gain or loss of species or functional groups (as opposed to replacement was driving dissimilarity patterns. Overall, our results suggest that whereas evolutionary processes (i.e., historical connection and dispersal routes across Bolivia create a template of diversity patterns across the country, ecological mechanisms modify these templates, decoupling the observed patterns of functional, taxonomic and phylogenetic diversity in Bolivian bats. Our results suggests that elevation represents an important source of variability among diversity patterns for each dimension of diversity considered. Further, we found that neither phylogenetic nor taxonomic diversity can fully account for

  7. Effects of competition and facilitation on species assemblage in two types of tropical cloud forest.

    Directory of Open Access Journals (Sweden)

    Wenxing Long

    Full Text Available Competition and facilitation between tree individuals are two kinds of non-random processes influencing the structure and functioning of forest communities, but how these two plant-plant interactions change along gradient of resources or environments remains very much a matter of debate. We developed a null model to test the size-distance regression, and assessed the effects of competition and facilitation (including interspecific interactions, intraspecific interactions and overall species interactions on each adult tree species assemblage [diameter at breast height (dbh ≥5 cm] across two types of tropical cloud forest with different environmental and resource regimes. The null model test revealed that 17% to 27% tree species had positive dbh-distance correlations while 11% to 19% tree species showed negative dbh-distance correlations within these two forest types, indicating that both competition and facilitation processes existed during the community assembly. The importance of competition for heterospecific species, and the intensity of competition for both heterospecific and overall species increased from high to low resources for all the shared species spanning the two forests. The importance of facilitation for conspecific and overall species, as well as that the intensity of facilitation for both heterospecific and conspecific species increased with increasing low air temperature stress for all the shared species spanning the two forests. Our results show that both competition and facilitation processes simultaneously affect parts of species assemblage in the tropical cloud forests. Moreover, the fact that nearly 50% species assemblage is not detected with our approaches suggest that tree species in these tropical forest systems are assembled with multiple ecological processes, and that there is a need to explore the processes other than the two biotic interactions in further researches.

  8. Taxonomic and Phylogenetic Determinants of Functional Composition of Bolivian Bat Assemblages

    Science.gov (United States)

    Aguirre, Luis F.; Montaño-Centellas, Flavia A.; Gavilanez, M. Mercedes; Stevens, Richard D.

    2016-01-01

    Understanding diversity patterns and the potential mechanisms driving them is a fundamental goal in ecology. Examination of different dimensions of biodiversity can provide insights into the relative importance of different processes acting upon biotas to shape communities. Unfortunately, patterns of diversity are still poorly understood in hyper-diverse tropical countries. Here, we assess spatial variation of taxonomic, functional and phylogenetic diversity of bat assemblages in one of the least studied Neotropical countries, Bolivia, and determine whether changes in biodiversity are explained by the replacement of species or functional groups, or by differences in richness (i.e., gain or loss of species or functional groups). Further, we evaluate the contribution of phylogenetic and taxonomic changes in the resulting patterns of functional diversity of bats. Using well-sampled assemblages from published studies we examine noctilionoid bats at ten study sites across five ecoregions in Bolivia. Bat assemblages differed from each other in all dimensions of biodiversity considered; however, diversity patterns for each dimension were likely structured by different mechanisms. Within ecoregions, differences were largely explained by species richness, suggesting that the gain or loss of species or functional groups (as opposed to replacement) was driving dissimilarity patterns. Overall, our results suggest that whereas evolutionary processes (i.e., historical connection and dispersal routes across Bolivia) create a template of diversity patterns across the country, ecological mechanisms modify these templates, decoupling the observed patterns of functional, taxonomic and phylogenetic diversity in Bolivian bats. Our results suggests that elevation represents an important source of variability among diversity patterns for each dimension of diversity considered. Further, we found that neither phylogenetic nor taxonomic diversity can fully account for patterns of functional

  9. Fish assemblages in Tanzanian mangrove creek systems influenced by solar salt farm constructions

    Science.gov (United States)

    Mwandya, Augustine W.; Gullström, Martin; Öhman, Marcus C.; Andersson, Mathias H.; Mgaya, Yunus D.

    2009-04-01

    Deforestation of mangrove forests is common occurrence worldwide. We examined fish assemblage composition in three mangrove creek systems in Tanzania (East Africa), including two creeks where the upper parts were partly clear-cut of mangrove forest due to the construction of solar salt farms, and one creek with undisturbed mangrove forest. Fish were caught monthly for one year using a seine net (each haul covering 170 m 2) within three locations in each creek, i.e. at the upper, intermediate and lower reaches. Density, biomass and species number of fish were lower in the upper deforested sites compared to the mangrove-fringed sites at the intermediate and lower parts in the two creeks affected by deforestation, whereas there were no differences among the three sites in the undisturbed mangrove creek system. In addition, multivariate analyses showed that the structure of fish assemblages varied between forested and clear-cut sites within the two disturbed creeks, but not within the undisturbed creek. Across the season, we found no significant differences except for a tendency of a minor increase in fish densities during the rainy season. At least 75% of the fishes were juveniles and of commercial interest for coastal fisheries and/or aquaculture. Mugil cephalus, Gerres oyena and Chanos chanos were the most abundant species in the forested sites. The dominant species in the clear-cut areas were M. cephalus and Elops machnata, which were both found in relatively low abundances compared to the undisturbed areas. The conversion of mangrove forests into solar salt farms not only altered fish assemblage composition, but also water and sediment conditions. In comparison with undisturbed areas, the clear-cut sites showed higher salinity, water temperature as well as organic matter and chlorophyll a in the sediments. Our results suggest that mangrove habitat loss and changes in environmental conditions caused by salt farm developments will decrease fish densities, biomass

  10. Seasonal dynamics of fish assemblage in a pond canal

    Czech Academy of Sciences Publication Activity Database

    Musil, J.; Adámek, Zdeněk; Baranyi, Ch.

    2007-01-01

    Roč. 15, č. 3-4 (2007), s. 217-226. ISSN 0967-6120. [New Challenges in Pond Aquaculture . České Budějovice, 26.04.2005-28.04.2005] Institutional research plan: CEZ:AV0Z60930519 Keywords : fish assemblage * pond canal * species richness * seasonal dynamics * alien species Subject RIV: GL - Fishing Impact factor: 0.828, year: 2007

  11. Testing olfactory foraging strategies in an Antarctic seabird assemblage

    OpenAIRE

    Nevitt, G A; Reid, K; Trathan, P.

    2004-01-01

    Procellariiform seabirds (petrels, albatrosses and shearwaters) forage over thousands of square kilometres for patchily distributed prey resources. While these birds are known for their large olfactory bulbs and excellent sense of smell, how they use odour cues to locate prey patches in the vast ocean is not well understood. Here, we investigate species-specific responses to 3-methyl pyrazine in a sub-Antarctic species assemblage near South Georgia Island (54degrees00' S, 36degrees00' W). Pyr...

  12. Mineral assemblage of the Červený vrch locality

    OpenAIRE

    Chvátal M

    2003-01-01

    Mineral assemblage was studied in shales and siltstones and the accompanying siliceous concretions of the Šárka Formation within the geological and palaeontological investigations of the temporary excavations made by the Skanska Company on the Červený vrch Hill in Prague-Vokovice, Czech Republic. Mineral identification was performed with the use of DRON-2.1 powder X-ray diffractometer (Institute of Geology, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague). M...

  13. Sewage pollution impact on Mediterranean rocky-reef fish assemblages

    OpenAIRE

    Azzurro, Ernesto; Matiddi, Marco; Fanelli, Emanuela; Guidetti, Paolo; Mesa, Gabriele La; Scarpato, Alfonso; Axiak, Victor

    2010-01-01

    Abstract The effects of sewage outfalls on subtidal fish assemblages were studied along the NW coasts of Malta (Sicily channel, Mediterranean Sea) by means of underwater visual census. The presence of two spatially distinct outfalls discharging untreated wastewaters allowed to use a balanced symmetrical ACI (After Control/Impact) design that consisted of two putatively impacted locations and two controls, with four sites nested in each location. Surveys were performed in 2006 at tw...

  14. THE YARMOUKIAN POTTERY ASSEMBLAGE OF TELL ABU SUWWAN, JORDAN

    OpenAIRE

    Al Nahar, Maysoon; Kafafi, Zeidan

    2015-01-01

    The archaeological excavations conducted at the site Tell Abu Suwwan indicated that it was continuously occupied during two main periods from the Middle Pre-Pottery Neolithic B through the Pottery Neolithic (Yarmoukian). The main focus of this paper is to study the pottery assemblage encountered in the Yarmoukian strata at Abu Tell Suwwan. Excavations at Tell Abu Suwwan in 2005 - 2008 yielded a total of 488 pieces of Yarmoukian pottery. The sample under study includes 86 Yarmoukian pottery sh...

  15. Characterizing lentic freshwater fish assemblages using multiple sampling methods

    Science.gov (United States)

    Fischer, Jesse R.; Quist, Michael

    2014-01-01

    Characterizing fish assemblages in lentic ecosystems is difficult, and multiple sampling methods are almost always necessary to gain reliable estimates of indices such as species richness. However, most research focused on lentic fish sampling methodology has targeted recreationally important species, and little to no information is available regarding the influence of multiple methods and timing (i.e., temporal variation) on characterizing entire fish assemblages. Therefore, six lakes and impoundments (48–1,557 ha surface area) were sampled seasonally with seven gear types to evaluate the combined influence of sampling methods and timing on the number of species and individuals sampled. Probabilities of detection for species indicated strong selectivities and seasonal trends that provide guidance on optimal seasons to use gears when targeting multiple species. The evaluation of species richness and number of individuals sampled using multiple gear combinations demonstrated that appreciable benefits over relatively few gears (e.g., to four) used in optimal seasons were not present. Specifically, over 90 % of the species encountered with all gear types and season combinations (N = 19) from six lakes and reservoirs were sampled with nighttime boat electrofishing in the fall and benthic trawling, modified-fyke, and mini-fyke netting during the summer. Our results indicated that the characterization of lentic fish assemblages was highly influenced by the selection of sampling gears and seasons, but did not appear to be influenced by waterbody type (i.e., natural lake, impoundment). The standardization of data collected with multiple methods and seasons to account for bias is imperative to monitoring of lentic ecosystems and will provide researchers with increased reliability in their interpretations and decisions made using information on lentic fish assemblages.

  16. Animal v. plant-based bait: does the bait type affect census of fish assemblages and trophic groups by baited remote underwater video (BRUV) systems?

    Science.gov (United States)

    Ghazilou, A; Shokri, M R; Gladstone, W

    2016-05-01

    Coral reef fish communities were sampled at the Nayband Marine Park, Iran, using baited remote underwater video stations (BRUVSs) which incorporated animal (i.e. frigate tuna Auxis thazard and beef liver), or plant-based baits (i.e. raw dough and raw dough-turmeric powder mix). The A. thazard was found to record significantly (P turmeric powder mix trials. There was also a significant difference in trophic composition of fish assemblages surveyed by animal- and plant-based baits which seemed to be due to variations in attraction patterns of carnivores and herbivores occurring at the earlier phases of each BRUV deployments. Meanwhile, the assemblage structure was comparable among fish assemblages sampled by different bait treatments, indicating that species-level responses to each bait type may be more complicated. In essence, the efficiency of mixed baits should also be examined in future studies. PMID:27170108

  17. Effects of a brine discharge over soft bottom Polychaeta assemblage

    Energy Technology Data Exchange (ETDEWEB)

    Pilar-Ruso, Yoana del [Dpto. de Ciencias del Mar y Biologia Aplicada, Universidad de Alicante, Campus de San Vicente del Raspeig, Ap. 99, E-03080, Alicante (Spain)], E-mail: yoana.delpilar@ua.es; Ossa-Carretero, Jose Antonio de la; Gimenez-Casalduero, Francisca; Sanchez-Lizaso, Jose Luis [Dpto. de Ciencias del Mar y Biologia Aplicada, Universidad de Alicante, Campus de San Vicente del Raspeig, Ap. 99, E-03080, Alicante (Spain)

    2008-11-15

    Desalination is a growing activity that has introduced a new impact, brine discharge, which may affect benthic communities. Although the role of polychaetes as indicators to assess organic pollution is well known, their tolerance to salinity changes has not been examined to such a great extent. The aim of this study was to examine the effect of brine discharge over soft bottom polychaete assemblage along the Alicante coast (Southeast Spain) over a two year period. Changes in the polychaete assemblage was analysed using univariate and multivariate techniques. We compared a transect in front of the discharge with two controls. At each transect we sampled at three depths (4, 10 and 15 m) during winter and summer. We have observed different sensitivity of polychaete families to brine discharges, Ampharetidae being the most sensitive, followed by Nephtyidae and Spionidae. Syllidae and Capitellidae showed some resistance initially, while Paraonidae proved to be a tolerant family. - The Polychaete assemblage is affected by the brine discharge of the Alicante desalination plant and we detect different sensitivity levels in polychaete families to brine impact.

  18. Response of Termite (Blattodea: Termitoidae) Assemblages to Lower Subtropical Forest Succession: A Case Study in Dinghushan Biosphere Reserve, China.

    Science.gov (United States)

    Li, Zhi-Qiang; Ke, Yun-Ling; Zeng, Wen-Hui; Zhang, Shi-Jun; Wu, Wen-Jing

    2016-02-01

    Termite (Blattodea: Termitoidae) assemblages have important ecological functions and vary in structure between habitats, but have not been studied in lower subtropical forests. To examine whether differences in the richness and relative abundance of termite species and functional groups occur in lower subtropical regions, termite assemblages were sampled in Dinghushan Biosphere Reserve, China, among pine forest, pine and broad-leaved mixed forest (mixed forest), and monsoon evergreen broad-leaved forest (monsoon forest). The dominant functional group was wood-feeding termites (family Termitidae), and the mixed forest hosted the greatest richness and relative abundance. Soil-feeding termites were absent from the lower subtropical system, while humus-feeding termites were sporadically distributed in mixed forest and monsoon forest. The species richness and functional group abundance of termites in our site may be linked to the forest succession. Altitude, soil temperature, air temperature, surface air relative humidity, and litter depth were significant influences on species and functional group diversity. PMID:26577861

  19. Is the nestedness of metazoan parasite assemblages of marine fishes from the southeastern Pacific coast a pattern associated with the geographical distributional range of the host?

    Science.gov (United States)

    González, M T; Oliva, M E

    2009-04-01

    Nested structure is a pattern originally described in island biogeography to characterize how a set of species is distributed among a set of islands. In parasite communities, nestedness has been intensively studied among individual fish from a locality. However, nested patterns among parasite assemblages from different host populations (localities) have scarcely been investigated. We recorded the occurrence of parasites in 9 fish species widely distributed along the southeastern Pacific coast to determine whether the ecto- and endoparasite assemblages of marine fishes show a nested structure associated with host distributional range. Nestedness was tested using Brualdi-Sanderson index of discrepancy (BR); and 5 null models incorporated in a 'Nestedness' programme (Ulrich, 2006). The ecto- and endoparasite richness do not show similar patterns of latitudinal gradients among fish hosts, with 33-66% of analysed ectoparasite assemblages, and 25-75% of endoparasite assemblages showing nested structures through the host distributional range. For ectoparasites, species richness gradients and nested structure (when present) might be associated with decreased host densities or could reflect negative environmental conditions in the distributional border of the host species, whereas for endoparasites might be caused by geographical breaks of prey or changes in prey availability (intermediate hosts). The sampled extension of the distributional range of the host species, as well as the lack of specificity of some parasites, could influence the detection of nestedness. PMID:19195414

  20. Evaluating habitat associations of a fish assemblages at multiple scales in a minimally disturbed stream on the Edwards Plateau, Central Texas

    Science.gov (United States)

    Cheek, Brandon D.; Grabowski, Timothy B.; Bean, Preston T.; Groeschel, Jillian R.; Magnelia, Stephan J.

    2016-01-01

    Habitat heterogeneity at multiple scales is a major factor affecting fish assemblage structure. However, assessments that examine these relationships at multiple scales concurrently are lacking. The lack of assessments at these scales is a critical gap in understanding as conservation and restoration efforts typically work at these levels.

  1. What is the importance of open habitat in a predominantly closed forest area to the dung beetle (Coleoptera, Scarabaeinae assemblage?

    Directory of Open Access Journals (Sweden)

    Fábio C. Costa

    2013-09-01

    Full Text Available What is the importance of open habitat in a predominantly closed forest to the dung beetle assemblage? The Atlantic Forest in Brazil is one of the most highly disturbed ecosystems and is mainly represented by fragmented areas. However, in places where human disturbances have ceased, certain areas are showing a natural regeneration pattern. The aim of the present study was to determine how the dung beetle assemblage responds to distinct habitat structures in a fragment of Atlantic Forest. For such, open and closed forest areas were sampled in a fragment of the Atlantic Forest in the northeastern region of Brazil. Pitfall traps baited with excrement and carrion were used to collect the beetles. A total of 7,267 individuals belonging to 35 species were captured. Canthon chalybaeus and C. mutabilis were restricted to open areas. Nearly 90% of the individuals of C. aff. simulans and Deltochilum aff. irroratum were identified in these areas. A higher percentage (> 50% of Canthon staigi, Dichotomius aff. depressicolis and D. aff. sericeus occurred in closed areas. Abundance differed between areas, with higher values in closed areas. Richness was not influenced by the habitat structure. NMDS ordination exhibited the segregation of areas and ANOSIM confirmed that this variable explained the assemblage of dung beetle species. The findings of the present study validate that open areas are associated to more restrictive conditions, limiting a higher abundance of dung beetle. Although situated near preserved fragments, the studied open areas increase the heterogeneity of the general landscape.

  2. Rapid inventory of the ant assemblage in a temperate hardwood forest: species composition and assessment of sampling methods.

    Science.gov (United States)

    Ellison, Aaron M; Record, Sydne; Arguello, Alexander; Gotelli, Nicholas J

    2007-08-01

    Ants are key indicators of ecological change, but few studies have investigated how ant assemblages respond to dramatic changes in vegetation structure in temperate forests. Pests and pathogens are causing widespread loss of dominant canopy tree species; ant species composition and abundance may be very sensitive to such losses. Before the experimental removal of red oak trees to simulate effects of sudden oak death and examine the long-term impact of oak loss at the Black Rock Forest (Cornwall, NY), we carried out a rapid assessment of the ant assemblage in a 10-ha experimental area. We also determined the efficacy in a northern temperate forest of five different collecting methods--pitfall traps, litter samples, tuna fish and cookie baits, and hand collection--routinely used to sample ants in tropical systems. A total of 33 species in 14 genera were collected and identified; the myrmecines, Aphaenogaster rudis and Myrmica punctiventris, and the formicine Formica neogagates were the most common and abundant species encountered. Ninety-four percent (31 of 33) of the species were collected by litter sampling and structured hand sampling together, and we conclude that, in combination, these two methods are sufficient to assess species richness and composition of ant assemblages in northern temperate forests. Using new, unbiased estimators, we project that 38-58 ant species are likely to occur at Black Rock Forest. Loss of oak from these forests may favor Camponotus species that nest in decomposing wood and open habitat specialists in the genus Lasius. PMID:17716467

  3. Phytoplankton assemblages of two intermittently open and closed coastal lakes in SE Australia

    Science.gov (United States)

    Liu, Dongyan; Morrison, R. John; West, Ronald J.

    2013-11-01

    Species composition and biomass of phytoplankton assemblages of a heavily impacted lake (Lake Illawarra) and a less impacted lake (Burrill Lake) in the South-Eastern region of Australia were compared based on bimonthly samples from three sites in each lake collected between April 2005 and April 2007. Lake Illawarra was generally characterized by higher nutrient concentrations and lower salinity than Burrill Lake. Phytoplankton assemblages displayed significant differences between the two lakes in terms of the dominant species composition and patterns of seasonal change rather than biomass. Diatoms were the dominant species in Lake Illawarra on most sampling occasions. In contrast, dinoflagellates (including toxic species) dominated in Burrill Lake during most seasons. Seasonal succession of phytoplankton in the two lakes did not follow the strict spring maximum that is generally observed in temperate waters. In Burrill Lake, maximum phytoplankton biomass often occurred in winter, while the maximum biomasses in Lake Illawarra occurred in autumn, winter and spring. The significant difference of nutrient structure between two lakes and warm temperate regime was regarded as important factors to affect these results. The results suggested care should be taken when relying on estuary health "indicators", such as chlorophyll a, rather than more detailed investigations of phytoplankton species compositions.

  4. Nocturnal planktonic assemblages of amphipods vary due to the presence of coastal aquaculture cages.

    Science.gov (United States)

    Fernandez-Gonzalez, V; Fernandez-Jover, D; Toledo-Guedes, K; Valero-Rodriguez, J M; Sanchez-Jerez, P

    2014-10-01

    Nocturnal pelagic swimming is common in the daily activity of peracarids in marine ecosystems. Fish farming facilities in coastal areas constitute an optimal artificial habitat for invertebrates such as amphipods, which can reach high abundance and biomass in fouling communities. Additionally, fish farms may modify the local oceanographic conditions and the distribution of pelagic communities. The aim of this study was to determine if nocturnal abundance and species composition of planktonic amphipod assemblages are affected by fish farm structures, using light traps as collecting method. A total of 809 amphipods belonging to 21 species were captured in farm areas, compared to 42 individuals and 11 species captured in control areas. The most important species contributing to the dissimilarity between farms and controls were the pelagic hyperiid Lestrigonus schizogeneios, the fouling inhabitants Ericthonius punctatus, Jassa marmorata, Stenothoe sp. and Caprella equilibra, and the soft-bottom gammarids Periculodes aequimanus and Urothoe pulchella. The great concentrations of planktonic amphipods at fish farm facilities is a result of the input of individuals from fouling communities attached to aquaculture facilities, along with the potential retention there of hyperiids normally present in the water column and migrant amphipods from soft sediments. Therefore, in addition to the effects of aquaculture on benthic communities, the presence of fish farms induces major changes in planktonic assemblages of invertebrates such as amphipods. PMID:25164018

  5. Mineral assemblage transformation of a metakaolin-based waste form after geopolymer encapsulation

    Science.gov (United States)

    Williams, Benjamin D.; Neeway, James J.; Snyder, Michelle M. V.; Bowden, Mark E.; Amonette, James E.; Arey, Bruce W.; Pierce, Eric M.; Brown, Christopher F.; Qafoku, Nikolla P.

    2016-05-01

    Mitigation of hazardous and radioactive waste can be improved through conversion of existing waste to a more chemically stable and physically robust waste form. One option for waste conversion is the fluidized bed steam reforming (FBSR) process. The resulting FBSR granular material was encapsulated in a geopolymer matrix referred to here as Geo-7. This provides mechanical strength for ease in transport and disposal. However, it is necessary to understand the phase assemblage evolution as a result of geopolymer encapsulation. In this study, we examine the mineral assemblages formed during the synthesis of the multiphase ceramic waste form. The FBSR granular samples were created from waste simulant that was chemically adjusted to resemble Hanford tank waste. Another set of samples was created using Savannah River Site Tank 50 waste simulant in order to mimic a blend of waste collected from 68 Hanford tank. Waste form performance tests were conducted using the product consistency test (PCT), the Toxicity Characteristic Leaching Procedure (TCLP), and the single-pass flow-through (SPFT) test. X-ray diffraction analyses revealed the structure of a previously unreported NAS phase and indicate that monolith creation may lead to a reduction in crystallinity as compared to the primary FBSR granular product.

  6. Fire ants actively control spacing and orientation within self-assemblages.

    Science.gov (United States)

    Foster, Paul C; Mlot, Nathan J; Lin, Angela; Hu, David L

    2014-06-15

    To overcome obstacles and survive harsh environments, fire ants link their bodies together to form self-assemblages such as rafts, bridges and bivouacs. Such structures are examples of self-assembling and self-healing materials, as ants can quickly create and break links with one another in response to changes in their environment. Because ants are opaque, the arrangement of the ants within these three-dimensional networks was previously unknown. In this experimental study, we applied micro-scale computed tomography, or micro-CT, to visualize the connectivity, arrangement and orientation of ants within an assemblage. We identified active and geometric mechanisms that ants use to obtain favorable packing properties with respect to well-studied packing of inert objects such as cylinders. Ants use their legs to push against their neighbors, doubling their spacing relative to random packing of cylinders. These legs also permit active control of their orientation, an ability ants use to arrange themselves perpendicularly rather than in parallel. Lastly, we found an important role of ant polymorphism in promoting self-aggregation: a large distribution of ant sizes permits small ants to fit between the legs of larger ants, a phenomenon that increases the number of average connections per ant. These combined mechanisms lead to low packing fraction and high connectivity, which increase raft buoyancy and strength during flash floods. PMID:24920836

  7. Time-consistent rearrangement of carabid beetle assemblages by an urbanisation gradient in Hungary

    Science.gov (United States)

    Magura, Tibor; Lövei, Gábor L.; Tóthmérész, Béla

    2008-09-01

    To examine the impact of urbanisation on arthropod biodiversity, carabid (Coleoptera: Carabidae) assemblages were studied over 2 years along a rural-urban gradient representing increasing levels of human disturbance. Carabids were collected by pitfall trapping during their whole activity period in lowland oak forest patches in and near the city of Debrecen, Eastern Hungary, over two seasons (2001-2002). Carabid activity density was significantly higher in the rural than in the two other areas, but there was no significant difference in species richness (measured as mean number of species caught/trap). The proportion of forest specialists significantly decreased from the rural towards the urban area, and the proportion of forest specialist species was significantly higher in the rural and suburban areas than in the urban one. In contrast, the relative activity density of generalist species significantly increased along the rural-urban gradient. Both the relative number of open-habitat species and their activity density were significantly higher in the urban forest fragments than in the suburban and rural ones. The patterns found were consistent between the 2 years. Multidimensional scaling indicated pronounced changes in species composition along the gradient; the assemblages in urban forest fragments were more variable than in the other areas. A large proportion of the variation in overall activity density, species richness and the proportion of carabids with different habitat affinities could be explained by structural habitat variables (percentage cover by canopy, leaf litter, herbs and decaying wood), and prey availability.

  8. Environmental and Anthropogenic Impacts on Avifaunal Assemblages in an Urban Parkland, 1976 to 2007

    Directory of Open Access Journals (Sweden)

    Sara Elizabeth Ormond

    2014-03-01

    Full Text Available Urban environments are unique, rapidly changing habitats in which almost half of the world’s human population resides. The effects of urbanisation, such as habitat (vegetation removal, pollution and modification of natural areas, commonly cause biodiversity loss. Long-term ecological monitoring of urban environments is vital to determine the composition and long-term trends of faunal communities. This paper provides a detailed view of long-term changes in avifaunal assemblages of the Adelaide City parklands and discusses the anthropogenic and environmental factors that contributed to the changes between 1976 and 2007. The Adelaide City parklands (ACP comprise 760 ha of land surrounding Adelaide’s central business district. Naturalist Robert Whatmough completed a 32-year survey of the ACP to determine the structure of the urban bird community residing there. Annual species richness and the abundance of birds in March and September months were analysed. Linear regression analysis was applied to species richness and abundance data of each assemblage. Resident parkland birds demonstrated significant declines in abundance. Native and introduced species also exhibited long-term declines in species richness and abundance throughout the 32-year period. Cycles of varying time periods indicated fluctuations in avian biodiversity demonstrating the need for future monitoring and statistical analyses on bird communities in the Adelaide City parklands.

  9. Development and short-term dynamics of macrofouling assemblages on fish-cage nettings in a tropical estuary

    Science.gov (United States)

    Madin, John; Chong, V. C.; Basri, Badrulnizam

    2009-06-01

    A study was conducted at a fish culture farm in the Jaha River estuary, Malaysia, to examine the structure and development of macrofouling assemblages on floating net-cages. The study was conducted during the dry (August-October 2001) and wet (December-February 2002) seasons. Biofouling on 1.6 cm mesh net panels (size 0.2 m × 2 m) suspended inside (P, T) and outside (O) experimental net-cages was monitored every week until net openings were completely occluded by macrofouling organisms (8 wk and 12 wk for dry and wet seasons respectively). Seven species (6 phyla) of sessile organisms and 23 species (3 phyla) of non-sessile associates were recorded. Macro-colonization of net panels began with the hydroid Plumularia sp. irrespective of season and treatment (P, T, and O), while other species only appeared after 1 or 2 weeks of immersion. Inside net-cages where water flow was slow (mean macroalgae ( Polysiphonia sp.), anthozoans (unidentified anemone), barnacles ( Balanus amphitrite), amphipods ( Gammaropsis sp. & Photis sp.), and tanaids ( Leptognathia sp.) were dominant on the net panels during the dry season. In the wet season, hydroid ( Plumularia sp.), mussel ( Xenostrobus mangle), and nematode abundance were however significant. With stronger water flow (mean ≈ 20 cm s -1) as occurring outside the net-cages, macrofouling assemblages for both seasons comprised mainly Plumularia sp. and Gammaropsis sp. The macrofouling assemblage showed a clear succession of species that occupied different layers of the net panels. The study shows that while organic enrichment and retarded water flow together enhance the development of macrofouling assemblages, salinity, depth, substrate (net) area and species competition specifically influence community structure, colonization, and depth distribution of the macrofouling organisms.

  10. Definition and kinematics of the northern of the Puerto Rico-Virgin Islands block and the Lesser Antilles forearc based on an updated and improved GPS velocity field and revised block models

    Science.gov (United States)

    Mattioli, G. S.; Jansma, P. E.; Stafford-Glenn, M.; Calais, E.

    2011-12-01

    The presence of small tectonic blocks the Greater Antilles, for example the Puerto Rico-Virgin Islands block (PRVI), which may be translating, rotating, and possibly internally deforming, has been proposed and some cases well-documented by several workers. In addition, the existence of a Lesser Antilles forearc has been proposed based on interplate earthquake slip vectors (Lopez et al. 2006). Manaker et al. (2008) used sparse GPS and earthquake slip data from the northeastern Caribbean to construct a DEFNODE block and fault model to constrain interseismic fault coupling among the microplates in the northeastern Caribbean. They concluded that the Enriquillo fault in Haiti could produce a Mw7.2, if the entire accumulated elastic strain was released in one event. On January 12, 2010, the strain was released in a Mw7.0 earthquake that left Port-au-Prince in rubble. The interseismic GPS velocity field has been updated for Hispanolia (Calais et al, 2010); in addition, new data have been collected in the northern Lesser Antilles (NLA) in 2009 as well as throughout the PRVI block in 2007 and 2011, and the existing GPS time series updated and transformed into ITRF05 (IGS05). GPS data from the NLA are consistent with a NLA forearc sliver that moves differently from the Caribbean and North American plates as originally proposed by Lopez et al. (2006). The forearc does not, however, continue as single tectonic entity across the Anegada Passage as previously suggested. Here we report revised DEFNODE models using both the original geometry and constraints of Manaker et al. (2008) with an updated GPS data set as well as new models that explicitly include a forearc block. The models may be used to explicitly define the rotation parameters of the block as well as the coupling along block bounding faults. The original model geometry (without a forearc sliver) yields a higher reduced chi-squared (2.57 vs. 2.01), when additional the GPS velocities from NLA are used to condition the

  11. Variations in fluid transport and seismogenic properties in the Lesser Antilles subduction zone: constraints from joint active-source and local earthquake tomography

    Science.gov (United States)

    Paulatto, M.; Laigle, M.; Charvis, P.; Galve, A.

    2015-12-01

    The degree of coupling and the seismogenic properties of the plate interface at subduction zones are affected by the abundance of slab fluids and subducted sediments. High fluid input can cause high pore-fluid pressures in the subduction channel and decrease coupling leading to aseismic behaviour. Constraining fluid input and transfer is therefore important for understanding plate coupling and large earthquake hazard, particularly in places where geodetic and seismological constraints are scarce. We use P-wave traveltimes from several active source seismic experiments and P- and S-wave traveltimes from shallow and intermediate depth (ratio (> 1.80) on the top of the slab, at depths of up to 100 km. We interpret this high Vp/Vs ratio anomaly as evidence of elevated fluid content either as free fluids or as bound fluids in hydrated minerals (e.g. serpentinite). The strength and depth extent of the anomaly varies strongly from south to north along the subduction zone and correlates with variations in forearc morphology and with sediment input constrained by multi-channel seismic reflection profiles. The anomaly is stronger and extends to greater depth in the south, offshore Martinique, where sediment input is elevated due to the vicinity of the Orinoco delta. The gently dipping forearc slope observed in this region may be the result of weak coupling of the plate interface. A high Vp/Vs ratio is also observed in the forearc likely indicating a fractured and water-saturated overriding plate. On the other hand the anomaly is weaker and shallower offshore Guadeloupe, where sediment input is low due to subduction of the Barracuda ridge. Here a strong plate coupling is likely responsible for uplifting the inner forearc and formation of the Karukera spur. We infer that variations in plate coupling modulated by slab fluid transport and release are a major factor in determining the distribution of seismic slip in the Lesser Antilles subduction zone.

  12. Spatial and temporal changes in bird assemblages in forest fragments in an eastern Amazonian savannah.

    Science.gov (United States)

    Cintra, Renato; Magnusson, William E; Albernaz, Ana

    2013-09-01

    We investigated the effects of forest fragmentation on bird assemblages in an Amazonian savannah landscape with forest fragments that have been isolated for more than 100 years. The study was conducted in areas surrounding the village of Alter do Chão (2°31'S, 55°00'W), Santarém, Brazil. Bird surveys and measurements of tree density were undertaken in 25 areas, with 19 plots in forest fragments of different sizes and six in an area of continuous forest. Data on forest-fragment size, perimeter, and isolation were obtained from a georeferenced satellite image. Variation in number of bird species recorded per plot was not related to vegetation structure (tree density). The number of bird species recorded per plot increased significantly only with fragment area, but was not influenced by fragment shape or degree of isolation, even when considering species from the savannah matrix in the analysis. Fragments had fewer rare species. Multivariate ordination analyses (multiple dimensional scaling, [MDS]) indicated that bird species composition changed along a gradient from small to large forest fragments and continuous-forest areas. In the Amazonian savannah landscapes of Alter do Chão, the organization and composition of bird assemblages in forest fragments are affected by local long-term forest-fragmentation processes. Differences in the number of bird species recorded per plot and assemblage composition between forest fragments and continuous forest were not influenced by forest structure, suggesting that the observed patterns in species composition result from the effects of fragmentation per se rather than from preexisting differences in vegetation structure between sites. Nevertheless, despite their long history of isolation, the forest fragments still preserve a large proportion (on average 80%) of the avifauna found in continuous-forest areas. The fragments at Alter do Chão are surrounded by natural (rather than planted) grassland, with many trees in the

  13. Analysis of fish assemblages in sectors along a salinity gradient based on species, families and functional groups

    Directory of Open Access Journals (Sweden)

    Ana Carolina dos Passos

    2013-12-01

    Full Text Available Here we test the effects of the east-west salinity gradient in the subtropical Paranaguá Bay Estuarine Complex (PEC on the structure of shallow water fish fauna, determined according to taxonomic (families and species and functional composition metrics. A total of 152 species were observed. The families with the largest number of species were the Sciaenidae, Carangidae, Haemulidae and Gobiidae. The most abundant species were Atherinella brasiliensis, Harengula clupeola, Anchoa januaria and Anchoa tricolor. Marine stragglers dominated in number of species, followed by marine migrants and estuarine species. Most species were zoobenthivores, followed by piscivores and zooplanktivores. Families and species more frequently associated with estuarine conditions dominated in the mesohaline sector, and those more frequently associated with marine conditions dominated in the euhaline sector. The fish assemblages along the estuarine salinity gradient were found to be better characterized by taxonomic metrics than by functional ones. This is most likely because individuals of all functional groups inhabit all salinity sectors, and thus these metrics are not useful for differentiating assemblages along salinity gradients. Our results differ from those of other studies in tropical and subtropical estuaries, which have emphasized the importance of functional groups in determining fish assemblages along salinity gradients.

  14. Influence of summer conditions on the larval fish assemblage in the eastern coast of Tunisia (Ionian Sea, Southern Mediterranean)

    Science.gov (United States)

    Zarrad, Rafik; Alemany, Francisco; Rodriguez, José-María; Jarboui, Othman; Lopez-Jurado, José-Luis; Balbin, Rosa

    2013-02-01

    The structure of the summer larval fish assemblage off the eastern coast of Tunisia and its relation to environmental conditions was studied, from ichthyoplankton samples taken during a survey conducted between 23rd June and 9th July 2008. A total of 68 larval fish taxa were identified, 52 to species level. The taxonomic composition and abundance of the larval fish assemblage showed high spatial heterogeneity. Mesoscale hydrographic features, such as eddies, seem to play an important role in the spatial distribution of fish larvae in the area, enhancing concentration and retention. The larval fish assemblage was dominated by the small pelagic species Sardinella aurita (26.6% of the total larval fish abundance), followed by Engraulis encrasicolus (22.6%), Spicara spp. (8.6%) and Mullus barbatus (6.8%). Shannon-Weaver index (H') ranged between 0 and 2.62. The highest values were found offshore, at 95 miles east of Sousse, over depths around 250 m. The diversity was higher in this region as a result of transport by currents and retention by eddies. It has also been shown that the eastern coast of Tunisia is a spawning ground for the tuna species Auxis rochei, Thunnus thynnus and Thunnus alalunga. Larvae of mesopelagic fishes represented 5.46% of the total abundance, with Cyclothone braueri, Ceratoscopelus maderensis and Lampanyctus crocodilus being the most important species. Canonical correspondence analysis (CCA) indicated that depth was the most important environmental factor in explaining species distribution.

  15. Dynamics of coral reef benthic assemblages of the Abrolhos Bank, eastern Brazil: inferences on natural and anthropogenic drivers.

    Science.gov (United States)

    Francini-Filho, Ronaldo B; Coni, Ericka O C; Meirelles, Pedro M; Amado-Filho, Gilberto M; Thompson, Fabiano L; Pereira-Filho, Guilherme H; Bastos, Alex C; Abrantes, Douglas P; Ferreira, Camilo M; Gibran, Fernando Z; Güth, Arthur Z; Sumida, Paulo Y G; Oliveira, Nara L; Kaufman, Les; Minte-Vera, Carolina V; Moura, Rodrigo L

    2013-01-01

    The Abrolhos Bank (eastern Brazil) encompasses the largest and richest coral reefs of the South Atlantic. Coral reef benthic assemblages of the region were monitored from 2003 to 2008. Two habitats (pinnacles' tops and walls) were sampled per site with 3-10 sites sampled within different reef areas. Different methodologies were applied in two distinct sampling periods: 2003-2005 and 2006-2008. Spatial coverage and taxonomic resolution were lower in the former than in the latter period. Benthic assemblages differed markedly in the smallest spatial scale, with greater differences recorded between habitats. Management regimes and biomass of fish functional groups (roving and territorial herbivores) had minor influences on benthic assemblages. These results suggest that local environmental factors such as light, depth and substrate inclination exert a stronger influence on the structure of benthic assemblages than protection from fishing. Reef walls of unprotected coastal reefs showed highest coral cover values, with a major contribution of Montastraea cavernosa (a sediment resistant species that may benefit from low light levels). An overall negative relationship between fleshy macroalgae and slow-growing reef-building organisms (i.e. scleractinians and crustose calcareous algae) was recorded, suggesting competition between these organisms. The opposite trend (i.e. positive relationships) was recorded for turf algae and the two reef-building organisms, suggesting beneficial interactions and/or co-occurrence mediated by unexplored factors. Turf algae cover increased across the region between 2006 and 2008, while scleractinian cover showed no change. The need of a continued and standardized monitoring program, aimed at understanding drivers of change in community patterns, as well as to subsidize sound adaptive conservation and management measures, is highlighted. PMID:23365655

  16. Dynamics of coral reef benthic assemblages of the Abrolhos Bank, eastern Brazil: inferences on natural and anthropogenic drivers.

    Directory of Open Access Journals (Sweden)

    Ronaldo B Francini-Filho

    Full Text Available The Abrolhos Bank (eastern Brazil encompasses the largest and richest coral reefs of the South Atlantic. Coral reef benthic assemblages of the region were monitored from 2003 to 2008. Two habitats (pinnacles' tops and walls were sampled per site with 3-10 sites sampled within different reef areas. Different methodologies were applied in two distinct sampling periods: 2003-2005 and 2006-2008. Spatial coverage and taxonomic resolution were lower in the former than in the latter period. Benthic assemblages differed markedly in the smallest spatial scale, with greater differences recorded between habitats. Management regimes and biomass of fish functional groups (roving and territorial herbivores had minor influences on benthic assemblages. These results suggest that local environmental factors such as light, depth and substrate inclination exert a stronger influence on the structure of benthic assemblages than protection from fishing. Reef walls of unprotected coastal reefs showed highest coral cover values, with a major contribution of Montastraea cavernosa (a sediment resistant species that may benefit from low light levels. An overall negative relationship between fleshy macroalgae and slow-growing reef-building organisms (i.e. scleractinians and crustose calcareous algae was recorded, suggesting competition between these organisms. The opposite trend (i.e. positive relationships was recorded for turf algae and the two reef-building organisms, suggesting beneficial interactions and/or co-occurrence mediated by unexplored factors. Turf algae cover increased across the region between 2006 and 2008, while scleractinian cover showed no change. The need of a continued and standardized monitoring program, aimed at understanding drivers of change in community patterns, as well as to subsidize sound adaptive conservation and management measures, is highlighted.

  17. Variation in Symbiodinium ITS2 sequence assemblages among coral colonies.

    Directory of Open Access Journals (Sweden)

    Michael Stat

    Full Text Available Endosymbiotic dinoflagellates in the genus Symbiodinium are fundamentally important to the biology of scleractinian corals, as well as to a variety of other marine organisms. The genus Symbiodinium is genetically and functionally diverse and the taxonomic nature of the union between Symbiodinium and corals is implicated as a key trait determining the environmental tolerance of the symbiosis. Surprisingly, the question of how Symbiodinium diversity partitions within a species across spatial scales of meters to kilometers has received little attention, but is important to understanding the intrinsic biological scope of a given coral population and adaptations to the local environment. Here we address this gap by describing the Symbiodinium ITS2 sequence assemblages recovered from colonies of the reef building coral Montipora capitata sampled across Kāne'ohe Bay, Hawai'i. A total of 52 corals were sampled in a nested design of Coral Colony(Site(Region reflecting spatial scales of meters to kilometers. A diversity of Symbiodinium ITS2 sequences was recovered with the majority of variance partitioning at the level of the Coral Colony. To confirm this result, the Symbiodinium ITS2 sequence diversity in six M. capitata colonies were analyzed in much greater depth with 35 to 55 clones per colony. The ITS2 sequences and quantitative composition recovered from these colonies varied significantly, indicating that each coral hosted a different assemblage of Symbiodinium. The diversity of Symbiodinium ITS2 sequence assemblages retrieved from individual colonies of M. capitata here highlights the problems inherent in interpreting multi-copy and intra-genomically variable molecular markers, and serves as a context for discussing the utility and biological relevance of assigning species names based on Symbiodinium ITS2 genotyping.

  18. What is important for ant assemblages in temperate forest soils?

    OpenAIRE

    Tae-Sung Kwon

    2016-01-01

    Ant assemblages in the soil have been studied at eight forest sites (4 oak forest sites, and 4 pine forest sites) in four study areas (1 seminatural area, and 3 industrialized areas) in South Korea for 6 years from 2002 to 2010. Soil cores and Tullgren funnel were used for the ant survey. Ant surveys were carried out once per year in autumn (from late September to mid-October). The soil pH was lower in the industrialized than in the seminatural area, showing the acidified soils in the industr...

  19. The snake assemblage (Squamata: Serpentes of a Cerrado-Caatinga transition area in Castelo do Piauí, state of Piauí, Brazil

    Directory of Open Access Journals (Sweden)

    Francílio da Silva Rodrigues

    2011-08-01

    Full Text Available This study records and analyzes the diversity and structure of a snake assemblage in a transition area between Cerrado and Caatinga, in the municipality of Castelo do Piauí, state of Piauí, comparing the distribution and similarity of the species composition with other open localities already studied in Brazil. We used three complementary sampling methods: time constrained search (TCS, pitfall traps with drift fences (PFT, and incidental encounters (IE. During the TCS and PFT, 912 hours/observer and 6,468 days/trap were used, respectively. We estimated 23 species of snakes for the locality, although only 19 species were recorded. Philodryas nattereri Steindachner, 1870 (n = 10, Liophis poecilogyrus (Schlegel, 1837 (n = 9, Liophis viridis Günther, 1862 (n = 8 and Thamnodynastes sp. (n = 8 were the most abundant species. Terrestrial, cryptozoic, and diurnal snakes predominated in the assemblage (Boidae = 2 species, Dipsadidae = 12, Colubridae = 2, Elapidae = 1, Viperidae = 2. The results indicate that the fauna of the locality is similar with that of other open formations, especially the Caatinga, corroborating previous floristic studies. Comparisons between snake assemblages analyzed by different authors suggest structural differences between the assemblages of the Cerrado and the Caatinga, contradicting the hypothesis of mixed composition of fauna in these biomes.

  20. Biodiversity patterns of epifaunal assemblages associated with the gorgonians Eunicella gazella and Leptogorgia lusitanica in response to host, space and time

    KAUST Repository

    Carvalho, Susana

    2014-01-01

    Patterns of biodiversity (alpha- and beta-diversity), abundance and community structure of the epifaunal assemblages associated with two gorgonians, Eunicella gazella and Leptogorgia lusitanica, were analysed in relation to host, colony size, location and time. Colony size and time were the major factors shaping attendant assemblages. Patterns of alpha-diversity and beta-diversity were host-dependent. Assemblages associated with E. gazella showed a significant inter-annual variability for most of the metrics analysed, while in those associated with L. lusitanica only Shannon-Wiener varied significantly between years. In L lusitanica Hurlbert\\'s expected number of taxa was significantly lower in small-sized than in medium- to large-sized colonies, but an opposite pattern was detected for beta-diversity, reflecting the higher heterogeneity among small-sized colonies. The dbRDA analysis segregated the assemblages associated with each of the two hosts; the faunal patterns were mainly explained by colony size related attributes (area, number of branches and, to a lesser extent, width) and the "colonial" epibiont cover. However, we suggest that altogether they may act as a metacommunity, with high temporal and spatial fluidity in their composition and structure related to multiple factors including not only a component of stochasticity but also life history events, biotic interactions and response to habitat heterogeneity and environmental variability. (C) 2013 Elsevier B.V. All rights reserved.

  1. Black liquor and the hangover effect: fish assemblage recovery dynamics following a pulse disturbance

    OpenAIRE

    Kyle R. Piller; Geheber, Aaron D

    2015-01-01

    Anthropogenic perturbations impact aquatic systems causing wide-ranging responses, from assemblage restructuring to assemblage recovery. Previous studies indicate the duration and intensity of disturbances play a role in the dynamics of assemblage recovery. In August 2011, the Pearl River, United States, was subjected to a weak black liquor spill from a paper mill which resulted in substantial loss of fish in a large stretch of the main channel. We quantified resilience and recovery of fish a...

  2. The role of macrophytes in habitat structuring in aquatic ecosystems: methods of measurement, causes and consequences on animal assemblages' composition and biodiversity O papel das macrófitas na estruturação de habitat em ambientes aquáticos: métodos de medida, causas e consequências para a composição das assembléias animais e biodiversidade

    Directory of Open Access Journals (Sweden)

    Sidinei Magela Thomaz

    2010-06-01

    Full Text Available Aquatic macrophytes play an important role in structuring communities in aquatic environments. These plants provide physical structure, increase habitat complexity and heterogeneity and affect various organisms like invertebrates, fishes and waterbirds. The complexity provided by macrophytes has been exhaustively studied in aquatic environments. However, macrophyte complexity has rarely been measured in a standardized fashion, making comparisons among different studies and the establishment of general conclusions difficult. To address this issue, this review is focused on questions related to the habitat structural complexity provided by these plants, exploring: i how complexity has been viewed by ecologists, with an emphasis on macrophyte studies; ii the pros and cons of several methods used to quantify plant complexity; iii the consequences of habitat structuring by macrophytes on invertebrates and fish and possible causes, mediated by habitat complexity, that lead to changes in these animal assemblages; iv potential impacts of non-native macrophyte species on habitat complexity and v the importance of complexity provided by macrophytes to management strategies for maintaining aquatic biodiversity. We examined literature produced in both temperate and tropical regions, but prioritized the latter. We found a great variety of habitat complexity measurements that are applied to aquatic macrophytes to understand their influence on attached animal assemblages. A lack of standardization (considering the wide range of techniques and scales of resolution used limits comparisons between different studies exploring this subject, in which biological samples and physical substrates were used to explore these relationships. Macrophytes affect animal assemblages and promote biodiversity through a chain of mechanisms, related to habitat complexity, that involve the availability of shelter and feeding sites. Invasive macrophyte species may modify habitat

  3. Assemblage patterns of fish functional groups relative to habitat connectivity and conditions in floodplain lakes

    Science.gov (United States)

    Miyazono, S.; Aycock, J.N.; Miranda, L.E.; Tietjen, T.E.

    2010-01-01

    We evaluated the influences of habitat connectivity and local environmental factors on the distribution and abundance patterns of fish functional groups in 17 floodplain lakes in the Yazoo River Basin, USA. The results of univariate and multivariate analyses showed that species-environmental relationships varied with the functional groups. Species richness and assemblage structure of periodic strategists showed strong and positive correlations with habitat connectivity. Densities of most equilibrium and opportunistic strategists decreased with habitat connectivity. Densities of certain equilibrium and opportunistic strategists increased with turbidity. Forested wetlands around the lakes were positively related to the densities of periodic and equilibrium strategists. These results suggest that decreases in habitat connectivity, forested wetland buffers and water quality resulting from environmental manipulations may cause local extinction of certain fish taxa and accelerate the dominance of tolerant fishes in floodplain lakes. ?? 2010 John Wiley & Sons A/S.

  4. Sonication assisted assemblage of exotic polymer supported nanostructured bio-hybrid system and prospective application.

    Science.gov (United States)

    Konwarh, Rocktotpal; Shail, Manjeshree; Medhi, Tapas; Mandal, Manabendra; Karak, Niranjan

    2014-03-01

    This work was focused on sonication mediated immobilization of porcine pancreatic lipase (PPL) onto poly(ethylene glycol) supported silver-iron oxide hybrid nanoparticles (PEG-Ag/IONPs). Selected process parameters of sonication were optimized using response surface methodology. Sonication assisted assemblage of spherical PEG-Ag/IONPs and consequent evolution of nanorods post PPL immobilization were documented. The efficacy of the reported immobilization strategy was attested by the increased thermostability, storage stability and enhanced activity of the biocatalyst, suggestive of plausible structural modulations post immobilization. The commercial prospect of the antibacterial and magnetically recyclable system was vouched by its excellent compatibility with some commercial detergents for oil de-staining. PMID:24210814

  5. Earthworm assemblages in different intensity of agricultural uses and their relation to edaphic variables.

    Science.gov (United States)

    Falco, L B; Sandler, R; Momo, F; Di Ciocco, C; Saravia, L; Coviella, C

    2015-01-01

    The objective of this study was to relate earthworm assemblage structure with three different soil use intensities, and to indentify the physical, chemical, and microbiological soil variables that are associated to the observed differences. Three soil uses were evaluated: 1-Fifty year old naturalized grasslands, low use intensity; 2-Recent agricultural fields, intermediate use intensity, and 3-Fifty year old intensive agricultural fields, high use intensity. Three different sites for each soil use were evaluated from winter 2008 through summer 2011. Nine earthworm species were identified across all sampling sites. The sites shared five species: the native Microscolex dubius, and the introduced Aporrectodea caliginosa, A. rosea, Octalasion cyaneum, and O. lacteum, but they differed in relative abundance by soil use. The results show that the earthworm community structure is linked to and modulated by soil properties. Both species abundance and diversity showed significant differences depending on soil use intensity. A principal component analysis showed that species composition is closely related to the environmental variability. The ratio of native to exotic species was significantly lower in the intensive agricultural system when compared to the other two, lower disturbance systems. Microscolex dubius abundance was related to naturalized grasslands along with soil Ca, pH, mechanical resistance, and microbial respiration. Aporrectodea caliginosa abundance was related to high K levels, low enzymatic activity, slightly low pH, low Ca, and appeared related to the highly disturbed environment. Eukerria stagnalis and Aporrectodea rosea, commonly found in the recent agricultural system, were related to high soil moisture condition, low pH, low Ca and low enzymatic activity. These results show that earthworm assemblages can be good indicators of soil use intensities. In particular, Microscolex dubius, Aporrectodea caliginosa, and Aporrectodea rosea, showed different

  6. Earthworm assemblages in different intensity of agricultural uses and their relation to edaphic variables

    Directory of Open Access Journals (Sweden)

    LB Falco

    2015-05-01

    Full Text Available The objective of this study was to relate earthworm assemblage structure with three different soil use intensities, and to indentify the physical, chemical, and microbiological soil variables that are associated to the observed differences. Three soil uses were evaluated: 1-Fifty year old naturalized grasslands, low use intensity; 2-Recent agricultural fields, intermediate use intensity, and 3-Fifty year old intensive agricultural fields, high use intensity. Three different sites for each soil use were evaluated from winter 2008 through summer 2011. Nine earthworm species were identified across all sampling sites. The sites shared five species: the native Microscolex dubius, and the introduced Aporrectodea caliginosa, A. rosea, Octalasion cyaneum, and O. lacteum, but they differed in relative abundance by soil use. The results show that the earthworm community structure is linked to and modulated by soil properties. Both species abundance and diversity showed significant differences depending on soil use intensity. A principal component analysis showed that species composition is closely related to the environmental variability. The ratio of native to exotic species was significantly lower in the intensive agricultural system when compared to the other two, lower disturbance systems. Microscolex dubius abundance was related to naturalized grasslands along with soil Ca, pH, mechanical resistance, and microbial respiration. Aporrectodea caliginosa abundance was related to high K levels, low enzymatic activity, slightly low pH, low Ca, and appeared related to the highly disturbed environment. Eukerria stagnalis and Aporrectodea rosea, commonly found in the recent agricultural system, were related to high soil moisture condition, low pH, low Ca and low enzymatic activity. These results show that earthworm assemblages can be good indicators of soil use intensities. In particular, Microscolex dubius, Aporrectodea caliginosa, and Aporrectodea rosea

  7. Mollusc life and death assemblages on a tropical rocky shore as proxies for the taphonomic loss in a fossil counterpart

    DEFF Research Database (Denmark)

    Sørensen, Anne Mehlin; Surlyk, Finn

    2013-01-01

    lower taxonomic agreement to the death assemblage than found in previous published studies. Rocky shore life and death assemblages thus appear to show lower taxonomic agreement compared to muddy or sandy shelf assemblages due to the mix after death with the sandy beach assemblage. A hypothetical fossil......Comparison of a modern rocky shore mollusc life assemblage from Thailand with the associated death assemblage, and interpretation of the fossilization potential of the latter, are used to investigate the fidelity in reconstruction of ancient analogues. The fauna from the death assemblage represents...... species from the rocky shore and the associated sandy pocket beaches, and only a few exotic species from other, completely different habitats are present. The environmental fidelity between the life and death assemblage is thus high, with the majority of species from the death assemblage representing the...

  8. Synergistic effects of iron and temperature on Antarctic plankton assemblages

    Directory of Open Access Journals (Sweden)

    J. M. Rose

    2009-06-01

    Full Text Available Iron availability and temperature are important limiting factors for the biota in many areas of the world ocean, and both have been predicted to change in future climate scenarios. However, the impacts of combined changes in these two key factors on microbial trophic dynamics and nutrient cycling are unknown. We examined the relative effects of iron addition (+1 nM and increased temperature (+4°C on plankton assemblages of the Ross Sea, Antarctica, a region characterized by annual algal blooms and an active microbial community. Increased iron and temperature individually had consistently significant but relatively minor positive effects on total phytoplankton abundance, phytoplankton and microzooplankton community composition, as well as photosynthetic parameters and nutrient drawdown. Unexpectedly, increased iron had a consistently negative impact on microzooplankton abundance, most likely a secondary response to changes in phytoplankton community composition. When iron and temperature were increased in concert, the resulting interactive effects were greatly magnified. This synergy between iron and temperature increases would not have been predictable by examining the effects of each variable individually. Our results suggest the possibility that if iron availability increases under future climate regimes, the impacts of predicted temperature increases on plankton assemblages in polar regions could be significantly enhanced. Such synergistic and antagonistic interactions between individual climate change variables highlight the importance of multivariate studies for marine global change experiments.

  9. Pollen assemblages as paleoenvironmental proxies in the Florida Everglades

    Science.gov (United States)

    Willard, D.A.; Weimer, L.M.; Riegel, W.L.

    2001-01-01

    Analysis of 170 pollen assemblages from surface samples in eight vegetation types in the Florida Everglades indicates that these wetland sub-environments are distinguishable from the pollen record and that they are useful proxies for hydrologic and edaphic parameters. Vegetation types sampled include sawgrass marshes, cattail marshes, sloughs with floating aquatics, wet prairies, brackish marshes, tree islands, cypress swamps, and mangrove forests. The distribution of these vegetation types is controlled by specific environmental parameters, such as hydrologic regime, nutrient availability, disturbance level, substrate type, and salinity; ecotones between vegetation types may be sharp. Using R-mode cluster analysis of pollen data, we identified diagnostic species groupings; Q-mode cluster analysis was used to differentiate pollen signatures of each vegetation type. Cluster analysis and the modern analog technique were applied to interpret vegetational and environmental trends over the last two millennia at a site in Water Conservation Area 3A. The results show that close modern analogs exist for assemblages in the core and indicate past hydrologic changes at the site, correlated with both climatic and land-use changes. The ability to differentiate marshes with different hydrologic and edaphic requirements using the pollen record facilitates assessment of relative impacts of climatic and anthropogenic changes on this wetland ecosystem on smaller spatial and temporal scales than previously were possible. ?? 2001 Elsevier Science B.V.

  10. "Controlling ourselves, by ourselves": risk assemblages on Malaysia's assembly lines.

    Science.gov (United States)

    Root, Robin

    2008-01-01

    Since the early 1990s, the Malaysian government has identified factories as high risk for HIV and AIDS. Signaling epidemiological concerns over the rising rates of HIV among factory workers, a significant proportion of whom are women, the label also appeared to reconstitute stereotypes of factory women as dangerously sexual and of factories as immoral spaces. Drawing on ethnographic research in the export processing zones of Penang, Malaysia in the mid-1990s, I examine the meanings and experiences of HIV risk among factory women themselves. Data were analyzed using discourse and grounded theory methods, the former to identify women's multiple modes of rationalizing HIV risks, and the latter to theorize the sources and significance of women's HIV risk assemblages. The heuristic of assemblages as localized knowledge spaces helped to show that biomedical and socioreligious risk lexica operated not as fixed epistemological categories but as situational resources in women's risk scripts. Overall, women desired multiple risk knowledges to help them "control themselves by themselves," a project of reflexive self-shaping mediated by the diverse and discordant discourses of gender, ethnicity, and modernity in Malaysia that shaped how HIV risks were engendered and experienced. PMID:18958787

  11. Ecological patterns of Chironomidae assemblages in Dynaric karst springs

    Directory of Open Access Journals (Sweden)

    Płóciennik M.

    2016-01-01

    Full Text Available Springs are one of important freshwater habitats in the Dynaric Mountains. Nevertheless, there were no intensive studies on dipteran communities in the region. Here we present an ecological analysis of Chironomidae communities recorded from a set of 27 springs along the Cvrcka River mainstream (the Republic of Srpska, Bosnia and Herzegovina. Environmental classification of Cvrcka springs divide them into three groups reflecting the level of human impact. Chironomidae communities divide investigated springs into three groups more dependent on bottom substrate quality. CCA indicates that the hard bottom and altitude are primary (significant factors determining midge assemblages. Secondary factors influencing communities are oxygen concentration and conductivity. There are clear differences in diversity and abundance in these three types of spring communities. Type II aggregates natural sites for Cvrcka valley. Samples characterized by high abundance of Chironomus seems to be an outliers in Cvrcka canyon. Eucrenon and hypocrenon communities are distinct, but no differences in the diversity level or the environmental assemblage relation were recorded for both mesohabitats. This study proves that solely environmental classification of spring habitats reflects well human impact, but invertebrate communities may not clearly follow general classification, reacting to a set of natural and altered conditions.

  12. Early Holocene turnover, followed by stability, in a Caribbean lizard assemblage

    Science.gov (United States)

    Kemp, Melissa E.; Hadly, Elizabeth A.

    2016-03-01

    Understanding how communities are impacted by environmental perturbations is integral for addressing the ongoing biodiversity crisis that impacts ecosystems worldwide. The fossil record serves as a window into ancient interactions and the responses of communities to past perturbations. Here, we re-examine paleontological data from Katouche Bay, Anguilla, a Holocene site in the Lesser Antilles. We reveal that the site was more diverse than previously indicated, with long-term, continuous records of three genera of extant lizards (Anolis, Ameiva, and Thecadactylus), and the early Holocene presence of Leiocephalus, a large ground-dwelling lizard that has since been completely extirpated from the Lesser Antilles. The disappearance of Leiocephalus from Katouche Bay resulted in high turnover, decreased evenness, and decreased species richness-a trend that continues to the present day. Our body size reconstructions for the most abundant genus, Anolis, are consistent with the presence of only one species, Anolis cf. gingivinus, at Katouche Bay throughout the Holocene, contrary to previously published studies. Additionally, we find no evidence of dwarfism in A. cf. gingivinus, which contrasts with a global study of contemporary insular lizards. Our data reveal that the impacts of diversity loss on lizard communities are long lasting and irreversible over millennia.

  13. Multilocus genotyping of human Giardia isolates suggests limited zoonotic transmission and association between assemblage B and flatulence in children.

    Directory of Open Access Journals (Sweden)

    Marianne Lebbad

    2011-08-01

    Full Text Available BACKGROUND: Giardia intestinalis is one of the most common diarrhea-related parasites in humans, where infection ranges from asymptomatic to acute or chronic disease. G. intestinalis consists of eight genetically distinct genotypes or assemblages, designated A-H, and assemblages A and B can infect humans. Giardiasis has been classified as a possible zoonotic disease but the role of animals in human disease transmission still needs to be proven. We tried to link different assemblages and sub-assemblages of G. intestinalis isolates from Swedish human patients to clinical symptoms and zoonotic transmission. METHODOLOGY/PRINCIPAL FINDINGS: Multilocus sequence-based genotyping of 207 human Giardia isolates using three gene loci: ß-giardin, glutamate dehydrogenase (gdh, and triose phosphate isomerase (tpi was combined with assemblage-specific tpi PCRs. This analysis identified 73 patients infected with assemblage A, 128 with assemblage B, and six with mixed assemblages A+B. Multilocus genotypes (MLGs were easily determined for the assemblage A isolates, and most patients with this genotype had apparently been infected through anthroponotic transmission. However, we also found evidence of limited zoonotic transmission of Giardia in Sweden, since a few domestic human infections involved the same assemblage A MLGs previously reported in Swedish cats and ruminants. Assemblage B was detected more frequently than assemblage A and it was also more common in patients with suspected treatment failure. However, a large genetic variability made determination of assemblage B MLGs problematic. Correlation between symptoms and assemblages was found only for flatulence, which was significantly more common in children less than six years of age infected with assemblage B. CONCLUSIONS/SIGNIFICANCE: This study shows that certain assemblage A subtypes are potentially zoonotic and that flatulence is connected to assemblage B infections in young children. Determination

  14. Effects of single-tree selection harvesting on hymenopteran and saproxylic insect assemblages in the canopy and understory of northern temperate forests

    Institute of Scientific and Technical Information of China (English)

    Sandy M.Smith; Nurul Islam; M.Isabel Bellocq

    2012-01-01

    Insects respond to changes in microhabitat caused by canopy disturbance,and thus can be used to examine the ecological impacts of harvesting.Single-tree selection harvesting is the most common silvicultural system used to emulate local small-scale natural disturbance and maintain uneven-aged forest structure in temperate forests.Here,we test for differences in richness,abundance,and composition of hymenopteran and saproxylic insect assemblages at four different taxon levels (selected insect orders; and all hymenopteran families,and braconid subfamilies and morphospecies) between the canopy and understory of unharvested and single-tree selection harvested sites in a northern temperate forest from central Canada.Harvesting had no effect on insect assemblage richness,composition or abundance at the three highest taxon levels (order,family and subfamily).Similarly,richness and abundance at the lowest-taxon level (braconid morphospecies) were similar,although composition differed slightly between unharvested and harvested stands.Insect assemblages were vertically stratified,with generally higher abundance (for Diptera,Hymenoptera,some hymenopteran families and braconid subfamilies) and richness (for braconid morphospecies) in the understory than the canopy.In particular,composition of the braconid morphospecies assemblage showed relatively low similarity between the understory and canopy.Single-tree selection harvesting appears to influence wood-associated insect taxa only subtly through small changes in community composition at the lowest taxon level,and thus is recommended as a conservative approach for managing these northern temperate forests.

  15. Isotopic characteristics of canopies in simulated leaf assemblages

    Science.gov (United States)

    Graham, Heather V.; Patzkowsky, Mark E.; Wing, Scott L.; Parker, Geoffrey G.; Fogel, Marilyn L.; Freeman, Katherine H.

    2014-11-01

    The geologic history of closed-canopy forests is of great interest to paleoecologists and paleoclimatologists alike. Closed canopies have pronounced effects on local, continental and global rainfall and temperature patterns. Although evidence for canopy closure is difficult to reconstruct from the fossil record, the characteristic isotope gradients of the "canopy effect" could be preserved in leaves and proxy biomarkers. To assess this, we employed new carbon isotopic data for leaves collected in diverse light environments within a deciduous, temperate forest (Maryland, USA) and for leaves from a perennially closed canopy, moist tropical forest (Bosque Protector San Lorenzo, Panamá). In the tropical forest, leaf carbon isotope values range 10‰, with higher δ13Cleaf values occurring both in upper reaches of the canopy, and with higher light exposure and lower humidity. Leaf fractionation (Δleaf) varied negatively with height and light and positively with humidity. Vertical 13C enrichment in leaves largely reflects changes in Δleaf, and does not trend with δ13C of CO2 within the canopy. At the site in Maryland, leaves express a more modest δ13C range (∼6‰), with a clear trend that follows both light and leaf height. Using a model we simulate leaf assemblage isotope patterns from canopy data binned by elevation. The re-sampling (bootstrap) model determined both the mean and range of carbon isotope values for simulated leaf assemblages ranging in size from 10 to over 1000 leaves. For the tropical forest data, the canopy's isotope range is captured with 50 or more randomly sampled leaves. Thus, with a sufficient number of fossil leaves it is possible to distinguish isotopic gradients in an ancient closed canopy forest from those in an open forest. For very large leaf assemblages, mean isotopic values approximate the δ13C of carbon contributed by leaves to soil and are similar to observed δ13Clitter values at forested sites within Panamá, including the

  16. Recovery of macrobenthic assemblages following experimental sand burial

    Directory of Open Access Journals (Sweden)

    José J. Barrón

    2008-09-01

    Full Text Available This research was supported by a fund provided by the Instituto de Ciencias del Mar y Limnología (UNAM and a fund provided to Celia Olabarria in 2004 and 2005 by the University of Vigo for overseas short stays.AbstractPeriodic inundation by sand is a very common feature of rocky coasts throughout the world. Even so, there have been few direct observations or experiments to investigate the role of sediments on intertidal rocky shores. We designed a field experiment in Mazatlán Bay, Mexico, to test the initial impact and subsequent recovery of intertidal macrobenthic assemblages exposed to sand burial at two sites of varying wave exposure. Both sites supported different natural assemblages. Treatment plots for the addition of sediment and control plots (50 × 50 cm, separated by at least 1.5 m, were randomly placed across the mid-water tidal level. The initial response of the resident macrobenthos and the subsequent recolonization was monitored over a period of 95 days. The main effect of sediment deposition at both sites was mortality and removal of biota due to smothering. The recovery process was rapid and may in part have been the result of the mechanism by which the small, disturbed patches were recolonized. Most of the invertebrates colonized the patches as adults; several seaweeds exhibited vegetative growth as the major mechanism of colonization (e.g., Ulva lactuca Linnaeus, 1753, Amphiroa valonioides Yendo, 1902 and Chaetomorpha antennina (Borgensen Kutzing, 1849. The rate of recovery varied between the sites, however. Recovery of species numbers proceeded quickly at the sheltered site (day 7, but took 95 days at the exposed site. In contrast, biomass reached control levels by day 45 at the sheltered site, but already by day 15 at the exposed site. By day 95, the assemblages recovered to 83.5% and 81% similarity with the controls at the sheltered and exposed sites respectively. Although differences in wave exposure could be very

  17. Decadal trends in the pollinator assemblage of Eucryphia cordifolia in Chilean rainforests.

    Science.gov (United States)

    Smith-Ramírez, Cecilia; Ramos-Jiliberto, Rodrigo; Valdovinos, Fernanda S; Martínez, Paula; Castillo, Jessica A; Armesto, Juan J

    2014-09-01

    Long-term studies of plant-pollinator interactions are almost nonexistent in the scientific literature. The objective of the present study was to determine changes and trends in the pollinator assemblage of ulmo (Eucryphia cordifolia; Cunoniaceae), a canopy-emergent tree found in Chilean temperate rainforests. We assessed the temporal variability of the pollinator assemblage and identified possible modulators of the observed temporal shifts. We sampled insect visitors to the flowers of 16 individual trees of E. cordifolia during 10 consecutive flowering seasons (2000-2009), recording a total of 137 pollinator species with a mean number of species per year of 44. Only three pollinator species (2.2%) were recorded every year. Two bee species accounted for 50% of all insect visits to flowers. One bee species, Bombus dahlbomii (native), was dominant in one season, whereas Apis mellifera (exotic) dominated during the next season. These interannual shifts in population abundances presented first-order dynamics that were characterized by oscillations with a period of 2 years. Changes in the abundances of the dominant pollinators, as well as differences in temperature and precipitation during insect emergence and flowering, led to a nested temporal structure of pollinator composition. Furthermore, the abundances of less common pollinators were sensitive to the abundance of the dominant bee species and to monthly maximum temperatures and the average precipitation during spring and summer. Based on our results and those from other studies, we predict a decline in the numbers of Bombus dahlbomii and nondominant native pollinators in response to new exotic arrivals. PMID:25001339

  18. Factors affecting fish assemblages associated with gas platforms in the Mediterranean Sea

    Science.gov (United States)

    Consoli, Pierpaolo; Romeo, Teresa; Ferraro, Maria; Sarà, Gianluca; Andaloro, Franco

    2013-03-01

    Understanding the role played by offshore platforms in marine ecosystems is acquiring increasing importance worldwide. In this work, underwater visual census techniques were applied to describe spatial and temporal patterns of fish assemblages associated with extractive platforms. Data were collected during three seasons according to the following spatial factors: Location (Adriatic and Ionian Seas), Depth (0-6 m and 12-18 m) and Distance from the platform (external and internal). Both univariate and multivariate analyses showed highly significant differences for each factor assessed in this study, as well as for the interaction among said factors. Results indicated that artificial structures in both the Adriatic and Ionian Seas act as artificial reefs attracting reef-dwelling or partially reef-dwelling species, which are not present far from the platforms in open waters. Results also showed significant differences between Ionian and Adriatic fish assemblages, with a higher mean density of fish and a greater mean number of species in the latter basin. Boops boops, Chromis chromis and several species belonging to the Blennidae family most contributed to these differences. This is likely due to the eutrophication that involves the coast of the northern and central Adriatic, allowing a high production of fish, especially planctivorous. Thanks to the eutrophication, platforms located in this basin are characterized by a greater abundance of fouling organisms which offer a perfect habitat for cryptobenthic species, such as Blennids. Moreover, Thalassoma pavo and Scorpaena maderensis, thermophilic species, were more abundant in the Ionian platforms than in the Adriatic ones thus contributing to the dissimilarities between these two basins. Present results could bear strong implications for the environmental management of drilling and production activities in different basins. Assessing biodiversity in these highly complex contexts is a challenge for the near future, and

  19. Lions as Bone Accumulators? Paleontological and Ecological Implications of a Modern Bone Assemblage from Olduvai Gorge

    Science.gov (United States)

    Arriaza, Mari Carmen; Domínguez-Rodrigo, Manuel; Yravedra, José; Baquedano, Enrique

    2016-01-01

    Analytic models have been developed to reconstruct early hominin behaviour, especially their subsistence patterns, revealed mainly through taphonomic analyses of archaeofaunal assemblages. Taphonomic research is used to discern which agents (carnivores, humans or both) generate the bone assemblages recovered at archaeological sites. Taphonomic frameworks developed during the last decades show that the only large-sized carnivores in African biomes able to create bone assemblages are leopards and hyenas. A carnivore-made bone assemblage located in the short-grassland ecological unit of the Serengeti (within Olduvai Gorge) was studied. Taphonomic analyses of this assemblage including skeletal part representation, bone density, breakage patterns and anatomical distribution of tooth marks, along with an ecological approach to the prey selection made by large carnivores of the Serengeti, were carried out. The results show that this bone assemblage may be the first lion-accumulated assemblage documented, although other carnivores (namely spotted hyenas) may have also intervened through postdepositional ravaging. This first faunal assemblage potentially created by lions constitutes a new framework for neotaphonomic studies. Since lions may accumulate carcasses under exceptional circumstances, such as those documented at the site reported here, this finding may have important consequences for interpretations of early archaeological and paleontological sites, which provide key information about human evolution. PMID:27144649

  20. Bottom fish assemblages at the shelf and continental slope off East Greenland

    DEFF Research Database (Denmark)

    Jørgensen, Ole A; Hvingel, Carsten; Møller, P.R.

    2015-01-01

    benthic species were used for analyses of the fish fauna diversity and fish assemblages. Nine assemblages were found by a standard type of cluster analysis. A Bayesian multinomial logit model was then applied to calculate vectors of probabilities defining the likelihood of each haul belonging to each...

  1. Identification and mapping of bottom fish assemblages in Davis Strait and southern Baffin Bay

    DEFF Research Database (Denmark)

    Jørgensen, Ole A; Hvingel, Carsten; Møller, P. R.;

    2005-01-01

    multinomial logit model was then applied to calculate vectors of probabilities defining the likelihood of each haul belonging to each of the seven clusters. The spatial distribution of the conditional probabilities for each cluster (assemblage) was mapped by means of a geostatistical tool. Each assemblage...

  2. Phylogenetic clustering among aggressive competitors: evidence from odonate assemblages along a riverine gradient.

    Science.gov (United States)

    Saito, Victor S; Valente-Neto, Francisco; Rodrigues, Marciel Elio; de Oliveira Roque, Fabio; Siqueira, Tadeu

    2016-09-01

    Studies on phylogenetic community ecology usually infer habitat filtering when communities are phylogenetically clustered or competitive exclusion when communities are overdispersed. This logic is based on strong competition and niche similarity among closely related species-a less common phenomenon than previously expected. Dragonflies and damselflies are good models for testing predictions based on this logic because they behave aggressively towards related species due to mistaken identification of conspecifics. This behavior may drive communities toward phylogenetic overdispersion if closely related species frequently exclude each other. However, phylogenetically clustered communities could also be observed if habitat filtering and/or competitive asymmetry among distantly related species are major drivers of community assembling. We investigated the phylogenetic structure of odonate assemblages in central Brazil in a watershed characterized by variations in stream width, vegetation cover, aquatic vegetation, and luminosity. We observed general clustering in communities according to two indices of phylogenetic structure. Phylogenetic beta diversity coupled with Mantel tests and RLQ analysis evidenced a correlation between the riverine gradient and phylogenetic structure. Larger rivers with aquatic vegetation were characterized by anisopterans, while most zygopterans stayed in small and shaded streams. These results indicate niche conservatism in Odonata habitat occupancy, and that the environment is a major influence on the phylogenetic structure of these communities. We suggest that this is due to clade-specific ecophysiological requirements, and because closely related species may also have competitive advantages and dominate certain preferred habitats. PMID:27160426

  3. Mineral assemblage of the Červený vrch locality

    Directory of Open Access Journals (Sweden)

    Chvátal M

    2003-06-01

    Full Text Available Mineral assemblage was studied in shales and siltstones and the accompanying siliceous concretions of the Šárka Formation within the geological and palaeontological investigations of the temporary excavations made by the Skanska Company on the Červený vrch Hill in Prague-Vokovice, Czech Republic. Mineral identification was performed with the use of DRON-2.1 powder X-ray diffractometer (Institute of Geology, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague. Mineral composition was specified by the CamScan S4 (Cambridge scanning electron microscope equipped with Link ISIS 300 (Oxford energy dispersion system (Laboratory of Geological Institutes, Faculty of Science, Charles University.

  4. The 'pitchblende-nodule-assemblage' of Mitterberg (Salzburg, Austria)

    International Nuclear Information System (INIS)

    Radiometric investigations of the presently closed copper mine of Mitterberg, Salzburg, led to the discovery of uranium mineralizations. Samples with pitchblende nodules up to two inches in size were found in old mining dumps. Altaite, bournonite, brannerite, calvaverite, cinnabar, coloradoite, galena, native gold, hessite, metacinnabar, molybdenite, pyrite, pyrrhotite, sphalerite and thus far unknown mineral 'X', an alteration product of rammelsbergite, were identified by the author. U and Mo of the 'Nodule-Assemblage' are explained as mobilization products of weak, strata-bound uranium mineralizations in quartzites of the 'Violet Series', a Permo-Carboniferous sedimentary sequence cut by the main copper vein. The later uranium mineralization of presently unassessed economic potential will be discussed in another paper. Age determinations (KOEPPEL, in PETRASCHECK 1975) of the reniform pitchblende indicate a crystallization age of 90 million years. This implies that the copper mineralization of the main copper vein can be related to Upper-Cretaccous remobilization processes. (orig./HK) 891 HK

  5. Sequence of mineral assemblages in differentiated granitic pegmatites.

    Science.gov (United States)

    Norton, J.J.

    1983-01-01

    The sequence of mineral assemblages in internally zoned granitic pegmatites recognized by Cameron et al. (1949) is modified here to account for an observed vertical component, especially in feldspar compositions, in addition to the recognized outer contact-to-inner core differentiation process, and the importance of primary lithium minerals other than spodumene, such as petalite. The zonal patterns of 11 well-known granitic pegmatites are consistent with this revised sequence, with additional explanations for the repeated monomineralic zones of quartz or pollucite, etc. The crystallization history of zoned pegmatites is described in general terms, beginning with the magmatic crystallization which produces the outer zones. Aqueous fluid is exsolved continuously from the magma as relatively anhydrous phases precipitate, and plays an important role in the formation of the inner zones; its evolution is thought to be a major cause of pegmatite differentiation.-J.E.S.

  6. Petrogenesis of opaque assemblages in the Ningqiang carbonaceous chondrite

    Institute of Scientific and Technical Information of China (English)

    HSU; WeiBiao

    2007-01-01

    Numerous round to oblate opaque assemblages (OAs) are found in chondrules and matrix of the Ningqiang carbonaceous chondrite. They are mainly composed of Ni-rich metal,magnetite,Fe,Ni-sulfides,with minor amounts of phosphate,phosphoran-olivine,pyroxene and trace amounts of nano-sized platinum-group metal alloys. The mineralogy of Ningqiang OAs is very similar to that of OAs previously reported in Ca,Al-rich inclusions of CV chondrites. Being a rare mineral phase in nature,phosphoran-olivine is thought to form by nonequilibrium reactions between P-bearing molten metal and olivine crystals during rapid cooling. Its occurrence in Ningqiang OAs indicates that the precursor of OAs was locally produced during chondrule formation,rather than directly condensed from the solar nebula as previously thought. The petrographic and mineralogical characteristics of Ningqiang OAs reveal that OAs formed by low temperature alterations of pre-existing homogeneous alloys within chondrules on a planetary body.

  7. Description of viral assemblages associated with the Gorgonia ventalina holobiont

    Science.gov (United States)

    Hewson, I.; Brown, J. M.; Burge, C. A.; Couch, C. S.; LaBarre, B. A.; Mouchka, M. E.; Naito, M.; Harvell, C. D.

    2012-06-01

    The diversity and function of viruses in coral holobionts has only recently received attention. The non-reef building gorgonian octocoral, Gorgonia ventalina, is a major constituent of Caribbean reefs. We investigated viral communities associated with G. ventalina tissues to understand their role in gorgonian ecology. Pyrosequencing was used to prepare a total of 514,632 sequence reads of DNA- and RNA-based mixed-community viral genomes (metaviromes). RNA viral assemblages were comprised of primarily unidentifiable reads, with most matching host transcripts and other RNA metaviromes. DNA metaviromes were similar between healthy and diseased tissues and comprised of contiguous sequences (contigs) that matched primarily metazoan and bacterial proteins. Only ~5% of contigs matched viral proteins that were primarily cyanophage and viruses of Chlorella and Ostreococcus. Our results confirm that DNA and RNA viruses comprise a component of the gorgonian holobiont, suggesting that they may play a role in the ecology of G. ventalina.

  8. New and extraordinary Early Cambrian sponge spicule assemblage from China

    Science.gov (United States)

    Zhang, Xi-Guang; Pratt, Brian R.

    1994-01-01

    The fossil record of siliceous sponges, compared with that of other skeleton- secreting Metazoa, is poorly known, based as it is on disarticulated spicules and sporadically preserved body fossils. Abundant spicules recovered from Lower Cambrian strata in Shaanxi, China, essentially double the known morphological diversity of siliceous sponges for that interval of geologic time. These fossils, along with a comparable coeval fauna from South Australia, have a remarkably modern aspect, thereby demonstrating that the principal siliceous sponge groups and styles of body architecture were established quickly in the earliest Phanerozoic as part of the Cambrian "explosion" and that they inhabited a variety of low-energy, relatively deep water settings. The similarity of spicule shape and variation to that of younger assemblages reflects a conservative architecture for the siliceous sponges.

  9. Benthic macroinvertebrate assemblages in the US nearshore zone of Lake Erie, 2009: Status and linkages to landscape-derived stressors

    Science.gov (United States)

    Benthic macroinvertebrate assemblages have been used as indicators of ecological condition because their responses integrate localized environmental conditions of the sediments and overlying water. Assemblages of benthic invertebrates in the near coastal region are of particular...

  10. Long-term patterns of chironomid assemblages in a high elevation stream/lake network (Switzerland – Implications to global change

    Directory of Open Access Journals (Sweden)

    Brigitte Lods-Crozet

    2012-10-01

    Full Text Available A long-term monitoring program was initiated in 2002 on running and standing waters in a high elevation cirque landscape (Macun in the Swiss National Park. The region comprises contrasting basins with different water sources, a glacier-fed basin and two precipitation-fed basins. Sampling of 26 permanent and temporary ponds (or small lakes and of interconnecting streams (10 sites was conducted from 2002 to 2010. Pond macroinvertebrate assemblages were dominated by chironomids with 42 taxa. The Orthocladiinae were the dominant subfamily in richness and abundance with 22 taxa. The greatest diversity was found in ponds located in the south and outlet basins. The inter-year variability for the same pond is high, but no clear temporal trend was noticed in ponds frequently monitored ponds. The Orthocladiinae subfamily was also the richest in the stream sites where 33 taxa were collected. The north and south basins were separated on the basis of chironomid assemblages. The chironomid assemblages in the stream network shows a temporal trend from 2002 but it cannot be linked to any clear change at the community structure level. The higher richness and abundance in stream sites and ponds of the south basin could be related to a greater heterogeneity in water physico-chemistry and substrata, and by the presence of Bryophyta. The understanding of the environmental factors that influence faunal assemblages is crucial for the protection of this sensitive alpine pond network where a relatively high overall regional diversity (49 taxa is detected. From the literature, temperature is recognized as the driving force on changes in chironomid assemblages in alpine systems. Our results support the use of chironomids as flagship indicators in the assessment of climatic change in alpine landscapes.doi: 10.5324/fn.v31i0.1361.Published online: 17 October 2012.

  11. Baseline study of the spatio-temporal patterns of reef fish assemblages prior to a major mining project in New Caledonia (South Pacific).

    Science.gov (United States)

    Chabanet, Pascale; Guillemot, Nicolas; Kulbicki, Michel; Vigliola, Laurent; Sarramegna, Sébastien

    2010-01-01

    From 2008 onwards, the coral reefs of Koné (New Caledonia) will be subjected to a major anthropogenic perturbation linked to development of a nickel mine. Dredging and sediment runoff may directly damage the reef environment whereas job creation should generate a large demographic increase and thus a rise in fishing activities. This study analyzed reef fish assemblages between 2002 and 2007 with a focus on spatio-temporal variability. Our results indicate strong spatial structure of fish assemblages through time. Total species richness, density and biomass were highly variable between years but temporal variations were consistent among biotopes. A remarkable spatio-temporal stability was observed for trophic (mean 4.6% piscivores, 53.1% carnivores, 30.8% herbivores and 11.4% planktivores) and home range structures of species abundance contributions. These results are discussed and compared with others sites of the South Pacific. For monitoring perspectives, some indicators related to expected disturbances are proposed. PMID:20637479

  12. Évolution spatio-temporelle du volcanisme de Basse-Terre (Guadeloupe, Petites Antilles) revisitée à partir de nouvelles données géochronologiques, géochimiques et géomorphologiques

    OpenAIRE

    Ricci, Julia

    2014-01-01

    Lors de cette étude, 47 nouveaux âges ont été obtenus par la technique Cassignol-Gillot, complétant à 128 âges le nombre de données disponibles sur l'île de Basse-Terre. La très bonne reproductibilité des âges obtenus dans cette étude, et la cohérence de ces derniers sur l'ensemble des massifs, appuie l'utilisation de la méthode K-Ar pour la datation des laves des Petites Antilles. Les données géochronologiques ont été associés à des analyses géochimiques et géomorphologiques dans le but de c...

  13. The snake assemblage (Squamata: Serpentes) of a Cerrado-Caatinga transition area in Castelo do Piauí, state of Piauí, Brazil

    OpenAIRE

    Francílio da Silva Rodrigues; Ana Lúcia da Costa Prudente

    2011-01-01

    This study records and analyzes the diversity and structure of a snake assemblage in a transition area between Cerrado and Caatinga, in the municipality of Castelo do Piauí, state of Piauí, comparing the distribution and similarity of the species composition with other open localities already studied in Brazil. We used three complementary sampling methods: time constrained search (TCS), pitfall traps with drift fences (PFT), and incidental encounters (IE). During the TCS and PFT, 912 hours/ob...

  14. Fish assemblages across the Mediterranean Sea and the effects of protection from fishing = I Popolamenti ittici nel Mediterraneo e gli effetti della protezione dall’impatto della pesca

    OpenAIRE

    Guidetti, Paolo; Sala, E.; Ballesteros, Enric; Di Franco, Antonio; Hereu, B.; MacPherson, Enrique; Micheli, Fiorenza; Pais, Antonio; Panzalis, Pier Augusto; Rosenberg, A.; Zabala, Mikel

    2010-01-01

    Several studies have assessed the effectiveness of individual marine protected areas (MPAs) in protecting fish assemblages, but regional assessments of multiple parks are scarce. Here fish surveys using visual census were done in marine parks and fished areas at 31 locations across the Mediterranean Sea. Fish species richness, diversity and biomass (especially of top predators) were higher in MPAs compared to fished areas, and community structure differed significantly between MPAs and fis...

  15. The use of assemblage models to describe trace element partitioning, speciation, and fate: a review.

    Science.gov (United States)

    Groenenberg, Jan E; Lofts, Stephen

    2014-10-01

    The fate of trace elements in soils, sediments, and surface waters is largely determined by their binding to reactive components, of which organic matter, metal oxides, and clays are considered most important. Assemblage models, combining separate mechanistic complexation models for each of the reactive components, can be used to predict the solid-solution partitioning and speciation of trace elements in natural environments. In the present review, the authors provide a short overview of advanced ion-binding models for organic matter and oxides and of their application to artificial and natural assemblages. Modeling of artificial assemblages of mineral components and organic matter indicates that the interactions between organic and mineral components are important for trace element binding, particularly for oxyanions. The modeling of solid-solution partitioning in natural systems is generally adequate for metal cations but less so for oxyanions, probably because of the neglect of organic matter-oxide interactions in most assemblage models. The characterization of natural assemblages in terms of their components (active organic matter, reactive oxide surface) is key to successful model applications. Improved methods for characterization of reactive components in situ will enhance the applicability of assemblage models. Collection of compositional data for soil and water archetypes, or the development of relationships to estimate compositions from geospatially available data, will further facilitate assemblage model use for predictive purposes. PMID:24862928

  16. Niche overlap and species assemblage dynamics in an ageing pasture gradient in north-western France

    Science.gov (United States)

    Decaëns, T.; Margerie, P.; Renault, J.; Bureau, F.; Aubert, M.; Hedde, M.

    2011-05-01

    This study aims at describing the mechanisms of earthworm species assemblages in a temperate grassland ageing gradient. Earthworms were sampled by a combination of formaldehyde extraction and hand sorting. Density data were analysed by combining correspondence analysis (CA) and null model analyses of niche overlap patterns and morphological trait dispersion. The first axis of the CA arranged samples according to the pasture ageing gradient and separated "pioneer" (CA1-) from "old pasture" (CA1+) species assemblages. The second axis segregated two different assemblages (CA2- and CA2+) that were consistently represented along the ageing gradient and was assumed to represent intra-plot assemblage heterogeneity. Niche overlap according to soil organic C, C:N ratio and root biomass was higher than expected by chance (EBC) in most assemblages, and was higher when calculated for the whole regional species pool than for local assemblages. Morphological dispersion was random or lower than expected by chance for the regional species pool and both CA1- and CA1+, and higher than expected by chance for both CA2- and CA2+. These results indicate that: (1) habitat and dispersal constraints act as filters by allowing only those species with similar prerequisite traits into assemblages; (2) inter-specific competition limit composition in a further step by calling for a minimal level of overdispersion in morphological traits.

  17. C9.A/14 steelwork joints de poutres par plaque frontale : assemblages par gousset

    CERN Document Server

    2015-01-01

    Les Tables de résistances ultimes des assemblages boulonnés par plaque frontale et par gousset, complétées par une description des modèles de calcul et des exemples d’application, ont pour but de faciliter la tâche de l'ingénieur et du constructeur. Cette première partie C9.A/14 contient les chapitres suivants: - Joints de poutres par plaque frontale en acier S235 et S355 - Assemblages par gousset en acier S235 et S355 Les Tables contiennent des données relatives à la géométrie ainsi que les valeurs de calcul correspondantes des résistances ultimes des assemblages ; elles remplacent le chapitre « Assemblages par plaques frontales et boulons HR » des anciennes Tables C9.1 de 1983 / 2002. Le calcul de ces assemblages par plaque frontale est basé sur les hypothèses du modèle de la méthode des composants décrite dans la norme SN EN 1993-1-8. Les vérifications sont effectuées selon la norme SIA 263:2013. Les assemblages par gousset remplacent les assemblages par double cornière, (telle...

  18. Pampean lizard assemblage from subtropical Brazil: a temporal analysis

    Directory of Open Access Journals (Sweden)

    Gisele R. Winck

    2011-12-01

    Full Text Available The increasing human occupation of natural environments is one of the greatest threats to biodiversity. To mitigate the negative anthropogenic effects, it is necessary to understand the characteristics of natural populations and the natural history of species. A study was conducted with an assemblage of lizards from a disturbed area of the Pampa biome, from February 2001 to January 2004. The assemblage showed a unimodal seasonal pattern, with the recruitment period occurring during the warmer months. The captures were seasonal for two of the three monitored years, and concentrated within warmer months. The minimum temperature explained the number of catches for the assemblage as a whole. However, when the species were analyzed individually, the temperature only explained the seasonal occurrence of Teius oculatus. The abundance of species was significantly different in the third year of study for Cercosaura schreibersii and Ophiodes striatus. This latter species was no longer registered in the study area from May 2003 until the end of the study. Therefore, O. striatus may be more sensitive to environmental changes, considering the events of change in vegetation during the study. With frequent and increasing environmental disturbances, it is necessary to take conservation measures and encourage the increase of knowledge on Pampean lizards.O crescimento da ocupação humana sobre ambientes naturais é uma das maiores ameaças à biodiversidade. Para amenizar os efeitos negativos antropogênicos, é necessário entender as características das populações naturais, e a história natural das espécies. Um estudo foi conduzido com uma assembeia de lagartos de uma área perturbada do Pampa, de fevereiro de 2002 a janeiro de 2004. A assembleia apresentou padrão sazonal unimodal, com recrutamento ocorrendo durante os meses mais quentes. As capturas foram sazonais durante dois dos três anos monitorados, e concentradas nos meses mais quentes. A

  19. Effects of nutrient enrichment derived from fish farming activities on macroinvertebrate assemblages in a subtropical region of Hong Kong.

    Science.gov (United States)

    Gao, Qin-Feng; Cheung, Kwok-Leung; Cheung, Siu-Gin; Shin, Paul K S

    2005-01-01

    To study the correlation between nutrient enrichment derived from fish farming activities and changes in macrobenthic assemblages, a one-year field study was conducted in Kau Sai Bay marine fish culture zone of Hong Kong. Bimonthly sediment samples were collected at six stations: two at the fish cages, two near the boundary of the fish culture area, and two reference sites further away from the culture area. Sediment physico-chemical characteristics in terms of silt/clay fraction, moisture content, total organic carbon (TOC), total Kjeldahl nitrogen (TKN) and total phosphorus (TP) were analyzed. The macrobenthos (>0.5 mm) present in the sediment were sorted, identified and enumerated. On average, TOC, TKN and TP levels at the fish cage stations were 82.8%, 128.5% and 1315.7% higher than those at the reference stations, respectively. As a result, the N:P molar ratio was greatly reduced from 8.75 at the reference stations to 1.83 at the fish cage stations. Univariate and multivariate analyses revealed that diversity of macrofauna was significantly reduced and community structure differed at the fish cage stations relative to the reference sites. The intermediary stations near the fish culture area showed a transitional state of disturbance. Faunal diversity was negatively correlated with nutrient level, reflecting the adverse impacts of nutrient enrichment derived from fish farming activities on the benthic assemblages. Whilst in subtropical Asia-Pacific trash fish is the major feed for fish culture resulting in a higher nutrient loading and nutrient ratio accumulated in the sediment beneath the fish rafts, the effects of nutrient enrichment on macrobenthic assemblages are comparable to that in temperate waters owing to relatively high sediment metabolism rate and smaller fish culture scale in Hong Kong. PMID:16291200

  20. Diatom assemblage in a tropical lake of northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Lilian Rodrigues do Nascimento

    2010-02-01

    Full Text Available The composition and spatial variation of diatom assemblage in surface sediments of Caçó Lake (shallow, mesotrophic and weakly acid lake - Maranhão State, Brazil were analyzed in order to know the distribution pattern of the species along the lake during rainy season (April 1999. Four zones were established in the lake based on 21 diatoms species and habitat affinities. The first three zones (prime three meters deep to six meters deep were marked by the occurrence of Pinnularia gigas, Frustulia rhomboides, Encyonopsis krasskei, Eunotia camelus, E. femoriformis and E. monodon. Zone IV (seven to nine meters deep was inhabited mainly by Surirella biseriata and Fragilariforma floridana. During the beginning of the rainy season, the diatom assemblage in Caçó Lake was composed mainly by benthic and epiphytic forms that reflected the low lake levels and the abundance of littoral vegetation present in this lake.Com o objetivo de se conhecer a dinâmica espacial e a distribuição das diatomáceas contidas no sedimento superficial do lago Caçó, durante o período de chuvas (abril de 1999 foram realizadas coletas em um "transect" horizontal. A partir da observação destas coletas efetuadas a cada 1 metro pode-se observar que a distribuição das diatomáceas esteve fortemente ligada a ocorrência do banco de macrófitas da sua margem, com a ocorrência maciça das espécies epifíticas e bentônicas. A análise de agrupamento de dados permitiu uma melhor visualização, da sua distribuição a cada profundidade e também das associações específicas em cada zona. Os resultados deste estudo permitiram concluir que a ocorrência e distribuição das diatomáceas do Lago Caçó está fortemente ligada ao banco de macrófitas localizado em suas margens, definindo assim zonas características dentro do lago.

  1. Heavy mineral assemblages of the Storegga tsunami deposit

    Science.gov (United States)

    Cascalho, J.; Costa, P.; Dawson, S.; Milne, F.; Rocha, A.

    2016-04-01

    This study applies heavy mineral analysis to the Storegga tsunami deposit across a range of locations (Whale Firth, Maggie's Kettle Loch and Scatsta Voe) in Shetland (Scotland). The usefulness of this proxy is tested in the identification and characterization of these palaeotsunami units. Furthermore, provenance relationships are established based on the mineralogical content of tsunami deposits and their potential source. Finally, the capability of identifying different phases of tsunami inundation in an 8200 years old tsunami deposit is attempted. Our results show that, overall, tsunamigenic samples presented a clear dominance of garnets and amphiboles. While Whale Firth presented a more balanced distribution between these two mineral groups, in Maggie's Kettle Loch and Scatsta Voe the tsunamigenic samples are dominated by amphiboles (> 90% of transparent heavy minerals). Focusing on the two dominant heavy minerals (garnets and amphiboles) and their vertical variation, one could observe that garnets mimic the heavy mineral concentration variability - higher values at the base and decreasing values to the top. This effect of concentration of the heaviest of the heavy minerals assemblage presents similarities with the formation of beach placer deposits. In fact, based on the heavy mineral vertical variation of the tsunami deposits in Maggie's Kettle Loch, Scatsta Voe and Whale Firth it is possible to conclude that hornblende (most likely amphibole of the assemblage) has the lowest concentration factor indicating that its transport process is more efficient and consequently most of its particles eventually may have moved offshore in the backwash phase of the tsunami. Furthermore, the more platy shape of amphiboles also favours a slower deposition. The opposite can be observed for garnets, which require more energy to be transported (i.e. they are more difficult to entrain by the tsunami waves) and tend to be more easily preserved in the formation of a tsunamigenic

  2. Genome analysis and comparative genomics of a Giardia intestinalis assemblage E isolate

    Directory of Open Access Journals (Sweden)

    Andersson Jan O

    2010-10-01

    Full Text Available Abstract Background Giardia intestinalis is a protozoan parasite that causes diarrhea in a wide range of mammalian species. To further understand the genetic diversity between the Giardia intestinalis species, we have performed genome sequencing and analysis of a wild-type Giardia intestinalis sample from the assemblage E group, isolated from a pig. Results We identified 5012 protein coding genes, the majority of which are conserved compared to the previously sequenced genomes of the WB and GS strains in terms of microsynteny and sequence identity. Despite this, there is an unexpectedly large number of chromosomal rearrangements and several smaller structural changes that are present in all chromosomes. Novel members of the VSP, NEK Kinase and HCMP gene families were identified, which may reveal possible mechanisms for host specificity and new avenues for antigenic variation. We used comparative genomics of the three diverse Giardia intestinalis isolates P15, GS and WB to define a core proteome for this species complex and to identify lineage-specific genes. Extensive analyses of polymorphisms in the core proteome of Giardia revealed differential rates of divergence among cellular processes. Conclusions Our results indicate that despite a well conserved core of genes there is significant genome variation between Giardia isolates, both in terms of gene content, gene polymorphisms, structural chromosomal variations and surface molecule repertoires. This study improves the annotation of the Giardia genomes and enables the identification of functionally important variation.

  3. Carbon and nitrogen fluxes between beech and their ectomycorrhizal assemblage.

    Science.gov (United States)

    Valtanen, Kerttu; Eissfeller, Verena; Beyer, Friderike; Hertel, Dietrich; Scheu, Stefan; Polle, Andrea

    2014-11-01

    To determine the exchange of nitrogen and carbon between ectomycorrhiza and host plant, young beech (Fagus sylvatica) trees from natural regeneration in intact soil cores were labelled for one growing season in a greenhouse with (13)CO2 and (15)NO3 (15)NH4. The specific enrichments of (15)N and (13)C were higher in ectomycorrhizas (EMs) than in any other tissue. The enrichments of (13)C and (15)N were also higher in the fine-root segments directly connected with the EM (mainly second-order roots) than that in bulk fine or coarse roots. A strict, positive correlation was found between the specific (15)N enrichment in EM and the attached second-order roots. This finding indicates that strong N accumulators provide more N to their host than low N accumulators. A significant correlation was also found for the specific (13)C enrichment in EM and the attached second-order roots. However, the specific enrichments for (15)N and (13)C in EM were unrelated showing that under long-term conditions, C and N exchange between host and EMs are uncoupled. These findings suggest that EM-mediated N flux to the plant is not the main control on carbon flux to the fungus, probably because EMs provide many different services to their hosts in addition to N provision in their natural assemblages. PMID:24756632

  4. Continental drift and climate change drive instability in insect assemblages

    Science.gov (United States)

    Li, Fengqing; Tierno de Figueroa, José Manuel; Lek, Sovan; Park, Young-Seuk

    2015-06-01

    Global change has already had observable effects on ecosystems worldwide, and the accelerated rate of global change is predicted in the future. However, the impacts of global change on the stability of biodiversity have not been systematically studied in terms of both large spatial (continental drift) and temporal (from the last inter-glacial period to the next century) scales. Therefore, we analyzed the current geographical distribution pattern of Plecoptera, a thermally sensitive insect group, and evaluated its stability when coping with global change across both space and time throughout the Mediterranean region—one of the first 25 global biodiversity hotspots. Regional biodiversity of Plecoptera reflected the geography in both the historical movements of continents and the current environmental conditions in the western Mediterranean region. The similarity of Plecoptera assemblages between areas in this region indicated that the uplift of new land and continental drift were the primary determinants of the stability of regional biodiversity. Our results revealed that climate change caused the biodiversity of Plecoptera to slowly diminish in the past and will cause remarkably accelerated biodiversity loss in the future. These findings support the theory that climate change has had its greatest impact on biodiversity over a long temporal scale.

  5. Continental drift and climate change drive instability in insect assemblages.

    Science.gov (United States)

    Li, Fengqing; Tierno de Figueroa, José Manuel; Lek, Sovan; Park, Young-Seuk

    2015-01-01

    Global change has already had observable effects on ecosystems worldwide, and the accelerated rate of global change is predicted in the future. However, the impacts of global change on the stability of biodiversity have not been systematically studied in terms of both large spatial (continental drift) and temporal (from the last inter-glacial period to the next century) scales. Therefore, we analyzed the current geographical distribution pattern of Plecoptera, a thermally sensitive insect group, and evaluated its stability when coping with global change across both space and time throughout the Mediterranean region--one of the first 25 global biodiversity hotspots. Regional biodiversity of Plecoptera reflected the geography in both the historical movements of continents and the current environmental conditions in the western Mediterranean region. The similarity of Plecoptera assemblages between areas in this region indicated that the uplift of new land and continental drift were the primary determinants of the stability of regional biodiversity. Our results revealed that climate change caused the biodiversity of Plecoptera to slowly diminish in the past and will cause remarkably accelerated biodiversity loss in the future. These findings support the theory that climate change has had its greatest impact on biodiversity over a long temporal scale. PMID:26081036

  6. Edge effect on carabid assemblages along forest-grass transects

    Directory of Open Access Journals (Sweden)

    T. Magura

    2001-02-01

    Full Text Available During 1997 and 1998, we have tested the edge-effect for carabids along oak-hornbeam forest-grass transects using pitfall traps in Hungary. Our hypothesis was that the diversity of carabids will be higher in the forest edge than in the forest interior. We also focused on the characteristic species of the habitats along the transects and the relationships between their distribution and the biotic and abiotic factors.

    Our results proved that there was a significant edge effect on the studied carabid communities: the Shannon diversity increased significantly along the transects from the forest towards the grass. The diversity of the carabids were significantly higher in the forest edge and in the grass than in the forest interior. The carabids of the forest, the forest edge and the grass are separated from each other by principal coordinates analysis and by indicator species analysis (IndVal, suggesting that each of the three habitats has a distinct species assemblages. There were 5 distinctive groups of carabids: 1 habitat generalists, 2 forest generalists, 3 species of the open area, 4 forest edge species, and 5 forest specialists. It was demonstrated by multiple regression analyses, that the relative air moisture, temperature of the ground, the cover of leaf litter, herbs, shrubs and canopy cover, abundance of the carabids’ preys are the most important factors determining the diversity and spatial pattern of carabids along the studied transects.

  7. Solidification in a Supercomputer: From Crystal Nuclei to Dendrite Assemblages

    Science.gov (United States)

    Shibuta, Yasushi; Ohno, Munekazu; Takaki, Tomohiro

    2015-08-01

    Thanks to the recent progress in high-performance computational environments, the range of applications of computational metallurgy is expanding rapidly. In this paper, cutting-edge simulations of solidification from atomic to microstructural levels performed on a graphics processing unit (GPU) architecture are introduced with a brief introduction to advances in computational studies on solidification. In particular, million-atom molecular dynamics simulations captured the spontaneous evolution of anisotropy in a solid nucleus in an undercooled melt and homogeneous nucleation without any inducing factor, which is followed by grain growth. At the microstructural level, the quantitative phase-field model has been gaining importance as a powerful tool for predicting solidification microstructures. In this paper, the convergence behavior of simulation results obtained with this model is discussed, in detail. Such convergence ensures the reliability of results of phase-field simulations. Using the quantitative phase-field model, the competitive growth of dendrite assemblages during the directional solidification of a binary alloy bicrystal at the millimeter scale is examined by performing two- and three-dimensional large-scale simulations by multi-GPU computation on the supercomputer, TSUBAME2.5. This cutting-edge approach using a GPU supercomputer is opening a new phase in computational metallurgy.

  8. Simplification of arboreal marsupial assemblages in response to increasing urbanization.

    Directory of Open Access Journals (Sweden)

    Bronwyn Isaac

    Full Text Available Arboreal marsupials play an essential role in ecosystem function including regulating insect and plant populations, facilitating pollen and seed dispersal and acting as a prey source for higher-order carnivores in Australian environments. Primarily, research has focused on their biology, ecology and response to disturbance in forested and urban environments. We used presence-only species distribution modelling to understand the relationship between occurrences of arboreal marsupials and eco-geographical variables, and to infer habitat suitability across an urban gradient. We used post-proportional analysis to determine whether increasing urbanization affected potential habitat for arboreal marsupials. The key eco-geographical variables that influenced disturbance intolerant species and those with moderate tolerance to disturbance were natural features such as tree cover and proximity to rivers and to riparian vegetation, whereas variables for disturbance tolerant species were anthropogenic-based (e.g., road density but also included some natural characteristics such as proximity to riparian vegetation, elevation and tree cover. Arboreal marsupial diversity was subject to substantial change along the gradient, with potential habitat for disturbance-tolerant marsupials distributed across the complete gradient and potential habitat for less tolerant species being restricted to the natural portion of the gradient. This resulted in highly-urbanized environments being inhabited by a few generalist arboreal marsupial species. Increasing urbanization therefore leads to functional simplification of arboreal marsupial assemblages, thus impacting on the ecosystem services they provide.

  9. Spatial and seasonal patterns of ichthyoplankton assemblages in the Haizhou Bay and its adjacent waters of China

    Science.gov (United States)

    Li, Zengguang; Ye, Zhenjiang; Wan, Rong

    2015-12-01

    Surveys were conducted in five voyages in Haizhou Bay and its adjacent coastal area from March to December 2011 during full moon spring tides. The ichthyoplankton assemblages and the environmental factors that affect their spatial and seasonal patterns were determined. Totally 35 and 12 fish egg and larvae taxa were identified, respectively. Over the past several decades, the egg and larval species composition has significantly changed in Haizhou Bay and its adjacent waters, most likely corresponding with the alteration of fishery resources, which are strongly affected by anthropogenic activities and climate change. The Bray-Curtis dissimilarity index identified four assemblages: near-shore bay assemblage, middle bay assemblage and two closely related assemblages (near-shore/middle bay assemblage and middle/edge of bay assemblage). The primary species of each assemblage principally reflected the spawning strategies of adult fish. The near-shore bay assemblage generally occurred in near-shore bay, with depths measuring <20 m, and the middle bay assemblage generally occurred in the middle of bay, with depths measuring 20 to 40 m. Spatial and seasonal variations in ichthyoplankton in each assemblage were determined by interactions between biological behavioral traits and oceanographic features, particularly the variation of local conditions within the constraint of a general reproductive strategy. The results of Spearman's rank correlation analysis indicated that both fish egg and larval abundance were positively correlated with depth, which is critical to the oceanographic features in Haizhou Bay.

  10. Reef fish and benthic assemblages of the Trindade and Martin Vaz Island group, southwestern Atlantic

    Directory of Open Access Journals (Sweden)

    Guilherme Henrique Pereira-Filho

    2011-09-01

    Full Text Available The Trindade and Martin Vaz island group (TMVIG is located at about 1,120 km off the Brazilian coast. Despite its importance, highlighted by the presence of several endemic fish species, the TMVIG lacks detailed information on the structure of fish and benthic assemblages. Presented here is the first quantitative assessment of reef fish and benthic assemblages of the TMVIG in a depth gradient ranging from 5 to 45 m. Additional qualitative information on reef assemblages between 45 and 100 m was obtained using advanced gas diving techniques (TRIMIX and a remotely operated vehicle (ROV. Similarly to other Brazilian oceanic islands, the TMVIG possesses depauperated fish and benthic assemblages, possibly due to its isolation and small size in comparison to the mainland. Depth was the most important factor affecting the structure of fish assemblages, with the density of most fish species declining with depth. Deep reefs (> 45 m were characterized by the presence of extensive rhodolith beds and rocky reefs sparsely covered with crustose coralline algae, black coral (Cirripathes sp. and a few massive or plate-like reef corals. Part-time or obligatory planktivorous fishes (e.g. Cephalopholis furcifer and Clepticus brasiliensis also dominated deep reefs. Similar characteristics were recorded in mesophotic reef ecosystems across the Western Atlantic. Evidence of overfishing (obtained here and in other recent studies, the presence of four endemic and restricted range fish species, as well as the increase in number of new (and still undescribed endemic taxa, indicates that the adoption of precautionary conservation measures are urgently needed in order to maintain the fragile and unique ecosystems of the TMVIG.O conjunto insular de Trindade e Martin Vaz (CITMV está localizado a aproximadamente 1.120 km da costa brasileira. Apesar de sua importância, salientada pela presença de diversas espécies endêmicas de peixes, não existem informações detalhadas

  11. Within-lake distribution patterns of fish assemblages: the relative roles of spatial, temporal and random environmental factors in assessing fish assemblages using gillnets in a large and shallow temperate lake.

    Science.gov (United States)

    Specziár, A; György, A I; Erős, T

    2013-03-01

    In this study, the relative role of spatio-temporal factors and associated environmental variables (water transparency and temperature) were quantified in relation to gillnet samples of fishes in a large and shallow lake (Lake Balaton, Hungary). Most of the variance (56·1%) in the relative abundance data (%) was related to the vertical segregation of fishes. This gradient substantially affected the catch per unit effort (CPUE) by number of the dominant species, the surface-oriented bleak Alburnus alburnus and the benthic common bream Abramis brama. It also influenced total CPUE, mean fish mass and species richness and diversity. At the lake level, horizontal habitat heterogeneity (i.e. littoral v. offshore) accounted for only 8·3% of the total variance in relative abundance data, but was important in structuring the CPUE of the ruffe Gymnocephalus cernua and the pikeperch Sander lucioperca. The longitudinal environmental gradient (i.e. lake basin), year and season of sampling, water transparency and temperature had significant effects on relative abundance only at the habitat level, but were also important components of variability of CPUE in some species at the lake level. As sampling schemes need to consider the main gradients in fish assemblage distributions, the use of surface and pelagic gillnets should be more intensively incorporated in the study and monitoring of fish assemblages in shallow lakes and lake habitats. PMID:23464547

  12. Early decomposer assemblages of soil organisms in litterbags with vetch and rye roots

    DEFF Research Database (Denmark)

    Georgieva, Slavka; Christensen, Søren; Petersen, Henning; Gjelstrup, Peter; Thorup-Kristensen, Kristian

    2005-01-01

    The assemblages of microbial (bacteria and fungi), microfaunal (protozoa and nematodes) and mesofaunal (microarthropods) populations were studied in decomposing root residues from hairy vetch (Vicia villosa Roth) and rye (Secale cereale L.) in a litterbag field experiment. Litterbags containing...

  13. Spatial variation in the macrobenthic assemblages of intertidal seagrass along the long axis of an estuary

    Science.gov (United States)

    Barnes, R. S. K.; Ellwood, M. D. F.

    2012-10-01

    Invertebrate macrofaunal biodiversity within intertidal seagrass meadows was investigated over a salinity gradient of diverse and highly spatially variable downstream faunal assemblage changed to a less rich, less diverse and more uniform one that dominated the upstream stretch without any further upstream reduction in richness. Nevertheless, without loss of overall richness, assemblage composition changed, again rapidly, in the upper region of the upstream stretch to a zone dominated by the microgastropod Hydrobia, which otherwise occurs in the Knysna system only in highly sheltered regions of the downstream stretch where it is also dominant. The upstream faunal assemblage was a subset of that in the marine-influenced downstream region not a different replacing one. Position along the estuarine gradient accounted for 29% of total assemblage variation. Overall faunal abundance declined with distance upstream until the Hydrobia zone where it rose sharply, but there was no evidence of increase in density of those species remaining on putative release from competition.

  14. Categorizing basic factors driving soil genesis, pedovariability and plant assemblages in Mediterranean Temporary Wetlands (TWs)

    OpenAIRE

    Capra, Gian Franco; CARIA, MARIA CARMELA; Buondonno, Andrea; Seddaiu, Giovanna; Vacca, Sergio; Bagella, Simonetta

    2012-01-01

    A research was carried out in six Temporary Wetlands (TWs), located in north-western Sardinia (Italy), with the aim to categorize the basic factors driving and linking soil genesis and plant assemblages in Mediterranean basin.

  15. Coral reef fish assemblages along a disturbance gradient in the northern Persian Gulf: A seasonal perspective.

    Science.gov (United States)

    Ghazilou, Amir; Shokri, Mohammad Reza; Gladstone, William

    2016-04-30

    Seasonal dynamics of coral reef fish assemblages were assessed along a gradient of potential anthropogenic disturbance in the Northern Persian Gulf. Overall, the attributes of coral reef fish assemblages showed seasonality at two different levels: seasonal changes irrespective of the magnitude of disturbance level (e.g. species richness), and seasonal changes in response to disturbance level (e.g. total abundance and assemblage composition). The examined parameters mostly belonged to the second group, but the interpretation of the relationship between patterns of seasonal changes and the disturbance level was not straightforward. The abundance of carnivorous fishes did not vary among seasons. SIMPER identified the family Nemipteridae as the major contributor to the observed spatiotemporal variations in the composition of coral reef fish assemblages in the study area. PMID:26507514

  16. Linkages between benthic macroinvertebrate assemblages and landscape stressors in the US Great Lakes

    Science.gov (United States)

    We used multiple linear regression analysis to investigate relationships between benthic macroinvertebrate assemblages in the nearshore region of the Laurentian Great Lakes and landscape characteristics in adjacent watersheds. Benthic invertebrate data were obtained from the 201...

  17. Landform-Sediment Assemblages Units of the Upper Mississippi River Valley

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — Wisconsinan and Holocene Landform-Sediment Assemblages of the Upper Mississippi River Valley. Knowledge of the spatial distribution of natural and cultural...

  18. Environmental drivers of temporal succession in recent dinoflagellate cyst assemblages from a coastal site in the North-East Atlantic (Lisbon Bay, Portugal)

    DEFF Research Database (Denmark)

    Ribeiro, Sofia; Amorim, Ana

    2008-01-01

    Temporal changes in the community structure of recent dinoflagellate cyst assemblages of Lisbon Bay (Iberian upwelling system) were investigated between 2000 and 2005. The assemblages were diverse and characterized by high inter-annual variability, rather than a clear seasonal pattern. In order to...... identify the main environmental drivers of community changes, several regional (river runoff, rainfall, upwelling, radiation, daylength) and in situ (sea surface temperature, salinity, bottom and surface chlorophyll a concentration) environmental parameters were tested. Multivariate statistical analysis...... allowed the identification of water stability as the main environmental gradient influencing the community composition, with river runoff in the preceding rain season and upwelling being the two drivers of stratification and turbulence, respectively. Both these processes can be described as nutrient...

  19. Inferring large-scale patterns of niche evolution and dispersal limitation from the phylogenetic composition of assemblages: A case study on New World palms

    DEFF Research Database (Denmark)

    Eiserhardt, Wolf L.; Svenning, J.-C.; Baker, William J.;

    How fast species’ environmental tolerances can evolve is crucial for their survival prospect under climate change. Phylogenetic information can yield insights into the tempo of niche evolution. Phylogenetic community structure (PCS) complements the more widely used approach of studying niche...... parameters in a trait evolution framework: it avoids using summary statistics for niche parameters, keeps spatial information - and thus information on niche filling - and separates the effects of niche conservatism and dispersal limitation. We analyse palm assemblages in the Americas, hypothesising: 1......) there are centres of in situ-diversification defined by climate and geomorphology. 2) The phylogenetic relatedness of assemblages decreases both with increasing environmental dissimilarity and geographical distance, but a significant part of its variation is explained by environment alone and reflects niche...

  20. Comparisons of mammalian Giardia duodenalis assemblages based on the β-giardin, glutamate dehydrogenase and triose phosphate isomerase genes.

    Science.gov (United States)

    Scorza, Andrea V; Ballweber, Lora R; Tangtrongsup, Sahatchai; Panuska, Carla; Lappin, Michael R

    2012-10-26

    The objective of this study was to determine and compare the assemblages of Giardia duodenalis isolated from mammalian fecal samples using the β-giardin (bg), glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) genes. A total of 202 samples, either submitted to the Veterinary Diagnostic Laboratory (Parasitology) at Colorado State University or part of ongoing research studies, were typed. A subset of 50 dog samples were also assessed by the tpi-D-specific primers. Of these, 183 were from dogs, 13 were from cats, two were from llamas, and one each was from a calf, an alpaca, a sheep, and a horse. The majority of the dogs (171 of 183 isolates) in this study were infected with only dog-adapted Assemblage C or D. The tpi-D-specific primers confirmed that 28 of the samples that typed as Assemblage D by the bg and gdh genes were also Assemblage D by the tpi-D-specific primers. Only 12 isolates were Assemblage A alone or Assemblage A and Assemblage C or D. Of the 13 cat isolates, seven were Assemblage F, two were Assemblage D, three were Assemblage A and 1 contained both Assemblages C and D. The calf isolate was Assemblage E (gdh, tpi) and the alpaca (bg, gdh), llamas (gdh), sheep (bg, gdh, tpi) and horse (tpi) isolates were all Assemblage A. When the assemblage could be determined for more than one gene, 91 of 117 dog isolates gave consistent results and 8 of 9 cat isolates gave consistent results. PMID:22652427

  1. Plant assemblage composition and soil P concentration differentially affect communities of AM and total fungi in a semi-arid grassland.

    Science.gov (United States)

    Klabi, Rim; Bell, Terrence H; Hamel, Chantal; Iwaasa, Alan; Schellenberg, Mike; Raies, Aly; St-Arnaud, Marc

    2015-01-01

    Adding inorganic P- and N-fixing legumes to semi-arid grasslands can increase forage yield, but soil nutrient concentrations and plant cover may also interact to modify soil fungal populations, impacting short- and long-term forage production. We tested the effect of plant assemblage (seven native grasses, seven native grasses + the domesticated N-fixing legume Medicago sativa, seven native grasses + the native N-fixing legume Dalea purpurea or the introduced grass Bromus biebersteinii + M. sativa) and soil P concentration (addition of 0 or 200 P2O5 kg ha(-1) at sowing) on the diversity and community structure of arbuscular mycorrhizal (AM) fungi and total fungi over two consecutive years, using 454-pyrosequencing of 18S rDNA and ITS amplicons. Treatment effects were stronger in the wet year (2008) than the dry year (2009). The presence of an N-fixing legume with native grasses generally increased AM fungal diversity, while the interaction between soil P concentration and plant assemblage modified total fungal community structure in 2008. Excluding interannual variations, which are likely driven by moisture and plant productivity, AM fungal communities in semi-arid grasslands appear to be primarily affected by plant assemblage composition, while the composition of other fungi is more closely linked to soil P. PMID:25764537

  2. The dark side of springs: what drives small-scale spatial patterns of subsurface meiofaunal assemblages?

    OpenAIRE

    Barbara Fiasca; Fabio Stoch; Marie-Josè Olivier; Chafik Maazouzi; Marco Petitta; Alessia Di Cioccio; Diana M.P. Galassi

    2014-01-01

    Springs are amongst the most relevant Groundwater Dependent Ecosystems (GDEs) and are key research environments in freshwater ecology and biology. The strict dependency on ground water of surface spring biodiversity is well known, whereas the biodiversity occurring below the spring is very poorly known. This study analyzes copepod assemblages in the subsurface habitat of a karstic rheo-limnocrenic spring in relation to seventeen environmental parameters. Subsurface copepod assemblages were se...

  3. Taxonomy of the Crematogaster degeeri-species-assemblage in the Malagasy region (Hymenoptera: Formicidae)

    OpenAIRE

    Fisher, Brian L; Blaimer, Bonnie B.

    2013-01-01

    We revise the species-level taxonomy of the Crematogaster (Crematogaster) degeeri-species-assemblage, a group of related ants occuring in Madagascar and the wider Malagasy region, and further provide an identification key to all species-groups of the genus Crematogaster in this region. Within the C. degeeri-assemblage, we recognize twelve species based upon morphological data from worker, queen and male ants, as well as genetic data from the barcode region of cytochrome oxidase I. Seven new s...

  4. Predominance of Giardia lamblia assemblage A among iron deficiency anaemic pre-school Egyptian children.

    Science.gov (United States)

    Hussein, Eman M; Zaki, Wafaa M; Ahmed, Shahira A; Almatary, Amal M; Nemr, Nader I; Hussein, Abdalla M

    2016-04-01

    Intestinal parasites and nutritional deficiency can coexist and influence each other. This study aimed to clarify the association between Giardia genotypes and presence of iron deficiency anaemia (IDA) among pre-school Egyptian children. Two groups (IDA and non-anaemic) of giardiasis children (44/group) were selected according to their recovery response after treatment of giardiasis. Each group included 24 and 20 gastrointestinal symptomatic and asymptomatic, respectively. Giardia human genotypes were performed by intergenic spacer (IGS) gene based polymerase chain reaction (PCR) with high-resolution melting curve (HRM). PCR/HRM proved that Tms of assemblage A and B ranged from 79.31 ± 0.29 to 84.77 ± 0.31. In IDA patients, assemblages A and B were found among 40/44 (90.9 %) and 4/44 (9.1 %), respectively, while in non-anaemic patients, assemblages A and B were found in 10/44 (22.7 %) and 32/44 (72.7 %), respectively, beside two (4.6 %) cases had mixed infection. The difference was statistically significant. No significant relation was found between symptomatic or asymptomatic assemblages and IDA as assemblage A was found in 21/24 (87.5 %) and 19/20 (95 %) of symptomatic and asymptomatic, respectively, while 3/24 (12.5 %) and 1/20 (5 %) of assemblage B were symptomatic was asymptomatic, respectively. A significant relation was found between assemblage A subtypes distribution among IDA patients as AI and AII were detected on 23 (52.3 %) and 16 (36.4 %) of patients, respectively, while one case (2.3 %) had mixed infection. In conclusion, assemblage A is predominant among IDA giardiasis children suggesting its role in enhancing the occurrence of IDA while B has a protective role. PMID:26758448

  5. Leaf and root-associated fungal assemblages do not follow similar elevational diversity patterns

    OpenAIRE

    Coince, Aurore; Cordier, Tristan; Lengellé, Juliette; Defossez, Emmanuel,; Vacher, Corinne; Robin, Cécile; Buee, Marc; Marçais, Benoit

    2014-01-01

    The diversity of fungi along environmental gradients has been little explored in contrast to plants and animals. Consequently, environmental factors influencing the composition of fungal assemblages are poorly understood. The aim of this study was to determine whether the diversity and composition of leaf and root-associated fungal assemblages vary with elevation and to investigate potential explanatory variables. High-throughput sequencing of the Internal Transcribed Spacer 1 region was used...

  6. Saproxylic Beetle Assemblage Selection as Determining Factor of Species Distributional Patterns: Implications for Conservation

    OpenAIRE

    García López, Alejandra; Galante, Eduardo; Micó, Estefanía

    2016-01-01

    The knowledge of the distributional patterns of saproxylic beetles is essential for conservation biology due to the relevance of this fauna in the maintenance of ecological processes and the endangerment of species. The complex community of saproxylic beetles is shaped by different assemblages that are composed of species linked by the microhabitats they use. We evaluate how different the species distribution patterns that are obtained can be, depending on the analyzed assemblage and to what ...

  7. Effects of sea bass and sea bream farming (Western Mediterranean Sea) on peracarid crustacean assemblages

    OpenAIRE

    Fernandez-Gonzalez, Victoria; Sanchez-Jerez, Pablo

    2011-01-01

    Benthic soft–bottom assemblages are good indicators of environmental disturbance, such as coastal aquaculture, considering their rapid response in terms of diversity and abundance. The aim of this study was to evaluate the response of peracarid assemblages to the release of waste from coastal farming as these organisms play an important ecological role. Abundance and species richness did not show significant differences between farm and control localities but did show a high spatial variabili...

  8. Distribution patterns of fish assemblages in an Eastern Mediterranean intermittent river

    OpenAIRE

    Vardakas L.; Kalogianni E.; Zogaris S.; Koutsikos N.; Vavalidis T.; Koutsoubas D.; Skoulikidis N. Th.

    2015-01-01

    The distribution patterns of fish assemblages within streams can provide insights for river type classifications and may warrant specific conservation actions. However, there is limited knowledge of how fish assemblages assort along a longitudinal axis in Mediterranean intermittent streams. Patterns in spatial and temporal distribution of fish communities were analysed in a Mediterranean intermittent river (Evrotas River) located in Southern Greece, hosting three endemic range restricted spec...

  9. Ecological traits of fish assemblages from Mediterranean Europe and its implications when assessing human pressure

    OpenAIRE

    Ferreira, M. T.; Caiola, N.; Casals, F; Cortes, R.; Economous, A; Garcia-Jalon, D.; Ilhéu, M.; Martinez-Capel, F.; Oliveira, J.; PONT D.; Prenda, J.; Rogers, C.; De Sostoa, A.; Zogaris, S.

    2007-01-01

    Mediterranean river systems are characterised by more diverse fish assemblages and regional ecological processes compared with the rest of Europe. A data set from Mediterranean France, Iberia and Greece ( 2000 sites) was used to describe the characteristics of fish assemblages, explore their responses to anthropogenic disturbance and analyse the implications for river quality assessment. There was a southwards decline in species richness per site, but endemicity and proportion of alien spe...

  10. Leaf and root-associated fungal assemblages do not follow similar elevational diversity patterns.

    Directory of Open Access Journals (Sweden)

    Aurore Coince

    Full Text Available The diversity of fungi along environmental gradients has been little explored in contrast to plants and animals. Consequently, environmental factors influencing the composition of fungal assemblages are poorly understood. The aim of this study was to determine whether the diversity and composition of leaf and root-associated fungal assemblages vary with elevation and to investigate potential explanatory variables. High-throughput sequencing of the Internal Transcribed Spacer 1 region was used to explore fungal assemblages along three elevation gradients, located in French mountainous regions. Beech forest was selected as a study system to minimise the host effect. The variation in species richness and specific composition was investigated for ascomycetes and basidiomycetes assemblages with a particular focus on root-associated ectomycorrhizal fungi. The richness of fungal communities associated with leaves or roots did not significantly relate to any of the tested environmental drivers, i.e. elevation, mean temperature, precipitation or edaphic variables such as soil pH or the ratio carbon∶nitrogen. Nevertheless, the ascomycete species richness peaked at mid-temperature, illustrating a mid-domain effect model. We found that leaf and root-associated fungal assemblages did not follow similar patterns of composition with elevation. While the composition of the leaf-associated fungal assemblage correlated primarily with the mean annual temperature, the composition of root-associated fungal assemblage was explained equally by soil pH and by temperature. The ectomycorrhizal composition was also related to these variables. Our results therefore suggest that above and below-ground fungal assemblages are not controlled by the same main environmental variables. This may be due to the larger amplitude of climatic variables in the tree foliage compared to the soil environment.

  11. Leaf and root-associated fungal assemblages do not follow similar elevational diversity patterns.

    Science.gov (United States)

    Coince, Aurore; Cordier, Tristan; Lengellé, Juliette; Defossez, Emmanuel; Vacher, Corinne; Robin, Cécile; Buée, Marc; Marçais, Benoît

    2014-01-01

    The diversity of fungi along environmental gradients has been little explored in contrast to plants and animals. Consequently, environmental factors influencing the composition of fungal assemblages are poorly understood. The aim of this study was to determine whether the diversity and composition of leaf and root-associated fungal assemblages vary with elevation and to investigate potential explanatory variables. High-throughput sequencing of the Internal Transcribed Spacer 1 region was used to explore fungal assemblages along three elevation gradients, located in French mountainous regions. Beech forest was selected as a study system to minimise the host effect. The variation in species richness and specific composition was investigated for ascomycetes and basidiomycetes assemblages with a particular focus on root-associated ectomycorrhizal fungi. The richness of fungal communities associated with leaves or roots did not significantly relate to any of the tested environmental drivers, i.e. elevation, mean temperature, precipitation or edaphic variables such as soil pH or the ratio carbon∶nitrogen. Nevertheless, the ascomycete species richness peaked at mid-temperature, illustrating a mid-domain effect model. We found that leaf and root-associated fungal assemblages did not follow similar patterns of composition with elevation. While the composition of the leaf-associated fungal assemblage correlated primarily with the mean annual temperature, the composition of root-associated fungal assemblage was explained equally by soil pH and by temperature. The ectomycorrhizal composition was also related to these variables. Our results therefore suggest that above and below-ground fungal assemblages are not controlled by the same main environmental variables. This may be due to the larger amplitude of climatic variables in the tree foliage compared to the soil environment. PMID:24971637

  12. Grass assemblages and diversity of conservation areas on the coastal plain south of Maputo Bay, Mozambique

    OpenAIRE

    S. J. Siebert; Fish, L.; M. M. Uiras; S. A. Izindine

    2004-01-01

    A floristic analysis of the grass species assemblages of the Licuati Forest and Maputo Elephant Reserves south of Maputo Bay, Mozambique, is presented. Sampling of grass data was undertaken in six previously described, major vegetation types. TWINSPAN divisions distinguished grass assemblages that are characteristic for these major vegetation types of the study area. The results were supported by an Indirect Gradient Analysis. Further TWINSPAN divisions of a larger Maputaland data set indicat...

  13. A new phyllopod bed-like assemblage from the Burgess Shale of the Canadian Rockies

    OpenAIRE

    Caron, Jean-Bernard; Gaines, Robert; Aria, Cédric; Mangano, Gabriela; Streng, Michael

    2014-01-01

    Burgess Shale-type fossil assemblages provide the best evidence of the ‘Cambrian explosion’. Here we report the discovery of an extraordinary new soft-bodied fauna from the Burgess Shale. Despite its proximity (ca. 40km) to Walcott’s original locality, the Marble Canyon fossil assemblage is distinct, and offers new insights into the initial diversification of metazoans, their early morphological disparity, and the geographic ranges and longevity of many Cambrian taxa. The arthropod-dominated ...

  14. A survey of odonate assemblages associated with selected wetland localities in southern Sri Lanka

    OpenAIRE

    Chandana, E.P.S.; Rajapaksha, A.C.D.; Samarasekara, W.G.K.H.

    2012-01-01

    The dragonflies and damselflies are a major insect group (Class Insecta; Order Odonata) associated with water courses. Odonate assemblages with reference to their habitat characters have not been widely studied in Sri Lanka. We have investigated odonate assemblages for a period of three months in selected localities in southern Sri Lanka with reference to the habitat characters. Bundala and Embillakala lagoons in Bundala National Park (A Ramsar wetland in Sri Lanka), “Kirala Kele” Eco-tourism...

  15. Spider assemblages in the overstory, understory, and ground layers of managed stands in the western boreal mixedwood forest of Canada.

    Science.gov (United States)

    Pinzon, Jaime; Spence, John R; Langor, David W

    2011-08-01

    Logging is the main human disturbance in the boreal forest; thus, understanding the effects of harvesting practices on biodiversity is essential for a more sustainable forestry. To assess changes in spider composition because of harvesting, samples were collected from three forest layers (overstory, understory, and ground) of deciduous and conifer dominated stands in the northwestern Canadian boreal mixedwood forest. Spider assemblages and feeding guild composition were compared between uncut controls and stands harvested to 20% retention. In total, 143 spider species were collected, 74 from the ground, 60 from the understory, and 71 from the overstory, and species composition of these three pools differed considerably among layers. Distinctive spider assemblages were collected from the canopy of each forest cover type but these were only slightly affected by harvesting. However, logging had a greater impact on the species composition in the understory and ground layers when compared with unharvested controls. Guild structure differed among layers, with wandering and sheet-weaving spiders dominant on the ground while orb-weaving and ambush spiders were better represented in the understory and overstory, respectively. Given the ecological importance of spiders and the expectation of faunal changes with increased harvesting, further efforts toward the understanding of species composition in higher strata of the boreal forest are needed. PMID:22251680

  16. Effects of an artificial reef system on demersal nekton assemblages in Xiangshan Bay, China

    Science.gov (United States)

    Jiang, Yazhou; Lin, Nan; Yuan, Xingwei; Jiao, Haifeng; Shentu, Jikang; Li, Shengfa

    2016-01-01

    In 2012, an artificial reef system was deployed in Xiangshan Bay, China, to enhance its fishery resources. To determine the effect of the artificial reef system on the demersal nekton assemblages, a beforeafter- control-impact study design was applied. Comparisons of assemblages from impact and control habitats revealed that the assemblage in the impact area had a gradual response to reef deployment. The assemblages in the impact and control areas changed in different ways after reef deployment. During the study period, total biomass, species richness and average body weight in the control area remained relatively stable, whereas there were significant increases in these indicators in the impact area. Responses to the reefs differed among nekton species, inducing assemblage succession in the reefs post-deployment. Sparus macrocephalus and Cynoglossus abbreviatus benefited most from reef deployment. Conversely, smallsized shrimp Palaemon gravieri showed a progressive decrease in biomass following reef deployment. Overall, the artificial reef system diversified the demersal nekton assemblage, enhanced the total biomass, and increased the proportion of large-sized species.

  17. Oil pipeline corridor through an intact forest alters ground beetle (Coleoptera: Carabidae) assemblages in southeastern Ohio.

    Science.gov (United States)

    Silverman, Bareena; Horn, David J; Purrington, Foster F; Gandhi, Kamal J K

    2008-06-01

    Litter-dwelling ground beetle (Coleoptera: Carabidae) assemblages were monitored 1 yr after the construction of a corridor for installation of an oil pipeline along a xeric ridge-top forest in southeastern Ohio. After the creation of the corridor, three distinct habitats were evident in these sites: open corridor, ecotone areas around the corridor, and undisturbed forest interior. Carabidae were collected using directional pitfall traps that were placed parallel and perpendicular to the corridor in each of the three habitats. Results indicate that more carabids were present in the ecotone than in the other two habitats. Carabid diversity as estimated by rarefaction was highest in the corridor followed by ecotone and forest interior. Generalist and forest specialists such as Synuchus impunctatus (Say), Carabus goryi Dejean, and Pterostichus trinarius (Casey) were present in greater numbers in the forest interior and ecotone assemblages. In contrast, open-habitat specialists such as Harpalus pensylvanicus (DeGeer) and Selenophorus opalinus (LeConte) were present in greater numbers in the corridor assemblages. Carabid assemblages of the corridor were distinct from those of the ecotone and forest interior, whereas the latter two habitats had very similar assemblages. The successional pathway of the corridor carabid assemblage will therefore be likely different from that of the forest interior and ecotone. Overall, results indicate that construction of the oil pipeline corridor had significant short-term effects on the carabid numbers, diversity, and species composition because of ensuing habitat changes and fragmentation of the forest. PMID:18559178

  18. Patterns of spatial variation of assemblages associated with intertidal rocky shores: a global perspective.

    Directory of Open Access Journals (Sweden)

    Juan José Cruz-Motta

    Full Text Available Assemblages associated with intertidal rocky shores were examined for large scale distribution patterns with specific emphasis on identifying latitudinal trends of species richness and taxonomic distinctiveness. Seventy-two sites distributed around the globe were evaluated following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org. There were no clear patterns of standardized estimators of species richness along latitudinal gradients or among Large Marine Ecosystems (LMEs; however, a strong latitudinal gradient in taxonomic composition (i.e., proportion of different taxonomic groups in a given sample was observed. Environmental variables related to natural influences were strongly related to the distribution patterns of the assemblages on the LME scale, particularly photoperiod, sea surface temperature (SST and rainfall. In contrast, no environmental variables directly associated with human influences (with the exception of the inorganic pollution index were related to assemblage patterns among LMEs. Correlations of the natural assemblages with either latitudinal gradients or environmental variables were equally strong suggesting that neither neutral models nor models based solely on environmental variables sufficiently explain spatial variation of these assemblages at a global scale. Despite the data shortcomings in this study (e.g., unbalanced sample distribution, we show the importance of generating biological global databases for the use in large-scale diversity comparisons of rocky intertidal assemblages to stimulate continued sampling and analyses.

  19. Reptile assemblage response to restoration of fire-suppressed longleaf pine sandhills.

    Science.gov (United States)

    Steen, David A; Smith, Lora L; Conner, L M; Litt, Andrea R; Provencher, Louis; Hiers, J Kevin; Pokswinski, Scott; Guyer, Craig

    2013-01-01

    Measuring the effects of ecological restoration on wildlife assemblages requires study on broad temporal and spatial scales. Longleaf pine (Pinus palustris) forests are imperiled due to fire suppression and subsequent invasion by hardwood trees. We employed a landscape-scale, randomized-block design to identify how reptile assemblages initially responded to restoration treatments including removal of hardwood trees via mechanical methods (felling and girdling), application of herbicides, or prescribed burning alone. Then, we examined reptile assemblages after all sites experienced more than a decade of prescribed burning at two- to thee-year return intervals. Data were collected concurrently at reference sites chosen to represent target conditions for restoration. Reptile assemblages changed most rapidly in response to prescribed burning, but reptile assemblages at all sites, including reference sites, were generally indistinguishable by the end of the study. Thus, we suggest that prescribed burning in longleaf pine forests over long time periods is an effective strategy for restoring reptile assemblages to the reference condition. Application of herbicides or mechanical removal of hardwood trees provided no apparent benefit to reptiles beyond what was achieved by prescribed fire alone. PMID:23495643

  20. The effects of fire on ant trophic assemblage and sex allocation

    Science.gov (United States)

    Caut, Stephane; Jowers, Michael J; Arnan, Xavier; Pearce-Duvet, Jessica; Rodrigo, Anselm; Cerda, Xim; Boulay, Raphaël R

    2014-01-01

    Fire plays a key role in ecosystem dynamics worldwide, altering energy flows and species community structure and composition. However, the functional mechanisms underlying these effects are not well understood. Many ground-dwelling animal species can shelter themselves from exposure to heat and therefore rarely suffer direct mortality. However, fire-induced alterations to the environment may change a species' relative trophic level within a food web and its mode of foraging. We assessed how fire could affect ant resource utilization at different scales in a Mediterranean forest. First, we conducted isotopic analyses on entire ant species assemblages and their potential food resources, which included plants and other arthropods, in burned and unburned plots 1 year postfire. Second, we measured the production of males and females by nests of a fire-resilient species, Aphaenogaster gibbosa, and analyzed the differences in isotopic values among workers, males, and females to test whether fire constrained resource allocation. We found that, in spite of major modifications in biotic and abiotic conditions, fire had little impact on the relative trophic position of ant species. The studied assemblage was composed of species with a wide array of diets. They ranged from being mostly herbivorous to completely omnivorous, and a given species' trophic level was the same in burned and unburned plots. In A. gibbosa nests, sexuals had greater δ15N values than workers in both burned and unburned plots, which suggests that the former had a more protein-rich diet than the latter. Fire also appeared to have a major effect on A. gibbosa sex allocation: The proportion of nests that produced male brood was greater on burned zones, as was the mean number of males produced per nest with the same reproductive investment. Our results show that generalist ants with relatively broad diets maintained a constant trophic position, even following a major disturbance like fire. However, the

  1. Epibenthic assemblages of the Tail of the Grand Bank and Flemish Cap (northwest Atlantic) in relation to environmental parameters and trawling intensity

    Science.gov (United States)

    Murillo, Francisco Javier; Serrano, Alberto; Kenchington, Ellen; Mora, José

    2016-03-01

    The structure, composition and distribution of epibenthic invertebrate assemblages on the Tail of the Grand Bank of Newfoundland and Flemish Cap (northwest Atlantic) were sampled using depth-stratified trawls. Faunal analysis of 152 uniquely identified taxa produced hierarchical synoptic tables of species associations with diagnostic indicators based on species fidelity. Twelve spatially coherent epibenthic megafaunal assemblages were identified, each with relatively sharp faunal boundaries and unique species attributes. These assemblages were shown a posteriori through ANOSIM to have statistically different species compositions, and were nested within three major regional-scale faunal groups: (I) the continental shelf of the Tail of the Grand Bank, typified by the sea cucumber Cucumaria frondosa and the sand dollar Echinarachnius parma; (II) the upper slope of the Grand Bank and top of Flemish Cap, typified by the sponges Radiella hemisphaerica and Iophon piceum and the sea star Ceramaster granularis; and (III) the lower slope of the Grand Bank and Flemish Cap, typified by the sea urchin Phormosoma placenta, and the sea pens Anthoptilum grandiflorum and Funiculina quadrangularis. Comparisons with literature on benthic species associations from a half century ago suggest that the assemblages identified herein have persisted in the area at least for decades. Detrended correspondence analysis (DCA) identified a well-defined biological gradient along the first axis with very high species turn-over. Ten environmental variables (including Trawling Intensity) were significantly correlated with the ordinated data. At one extreme the continental shelf faunal group (I) was associated with shallow depth (mostly, less than 200 m), coarse sediments and cold and fresh water associated with the Labrador Current. At the other extreme the lower slope faunal group (III; stations below 500-600 m throughout the study area) was strongly associated with deep water, muddy sediments, and

  2. U/Pb, Sm/Nd and Rb/Sr geochronological and isotopic study of northern Sierra Nevada ophiolitic assemblages, California

    Science.gov (United States)

    Saleeby, J. B.; Shaw, H. F.; Niemeyer, Sidney; Moores, E. M.; Edelman, S. H.

    1989-06-01

    Distinct ophiolitic assemblages occur as oceanic basement within three of the four regional tectonic belts of the northern Sierra Nevada. New U/Pb zircon, Sm/Nd and Rb/Sr data are presented for each assemblage, providing critical geochronological and isotopic constraints on the petrogenesis and tectonic evolution of the ophiolitic and associated ensimatic assemblages. Ophiolitic assemblages include from west to east the Smartville complex, Central belt and Feather River belt. The Smartville complex represents an island arc volcanic-plutonic sequence with a major late-stage sheeted dike swarm. The Sm/Nd systems from a wide compositional spectrum of rocks record a 178±21 Ma petrogenetic age and an ɛ Nd(T)=+9.2±0.6. Zircon U/Pb systems on an uppermost dacite yield a 164±2 Ma age, and on a number of plagiogranite screens and dikes from the sheeted complex 162±1 Ma ages. The Central and Feather River belts are structurally complex polygenetic assemblages. The U/Pb zircon and Sm/Nd systems record major ˜205 Ma and ˜315 Ma petrogenetic events respectively both involving depleted mantle derived magmas. Such magmatism probably occurred in marginal basin/transform systems developed within an older oceanic depleted mantle basement regime. Both Sm/Nd and U/Pb zircon systems show local components of Proterozoic sialic material. The sialic contaminants were probably introduced into the system as craton derived detritus. It is doubtful that any of the ophiolitic assemblages studied represent genetically related crust-upper mantle sequences generated during the development of new oceanic lithosphere. Integration of the geochronological data with geological relations reveals a pattern of petrogenesis and tectonics whereby progressively younger ensimatic terranes were added to the continental margin through time by plate convergence, and were ultimately welded into North American sial by a crosscutting batholithic belt. This accretionary pattern is reflected in both the

  3. Particle assemblage characterization in the Rhone River ROFI

    Science.gov (United States)

    Many, Gaël; Bourrin, François; Durrieu de Madron, Xavier; Pairaud, Ivane; Gangloff, Aurélien; Doxaran, David; Ody, Anouck; Verney, Romaric; Menniti, Christophe; Le Berre, David; Jacquet, Matthias

    2016-05-01

    An innovative experiment was carried out in the vicinity of the Rhône River mouth in February 2014. An instrumental package, composed of a CTD, a LISST-100 type B (1.25-250 μm), and a LISST-HOLO (20-2000 μm), was used to characterize the hydrological parameters and suspended particles properties (concentration, size, composition, shape, and effective density) in the region of freshwater influence (ROFI) of the Rhône River. Besides, a coastal SLOCUM glider, equipped with a CTD and optical backscattering sensors at several wavelengths, was deployed to detail the spatial description of the hydrological parameters and some particle properties. Large river discharge (annual flood ~ 5000 m3 s- 1) and strong wind conditions favored the dispersal of the river plume on the shelf. Surface suspended particulate matter concentrations decreased rapidly seaward from 20 mg L- 1 next to the river mouth to 1.5 mg L- 1 at the shelf break. A persistent bottom nepheloid layer was observed across the shelf with concentrations decreasing from 8 mg L- 1 at the coast to 1 mg L- 1 at the shelf break. Observations showed that most of suspended particles were mainly flocculated in micro and macro-flocs (30-400 μm) in inner-shelf waters. The particle assemblage in the Rhône River plume and in the bottom nepheloid layer became progressively finer seaward and the associated effective density increased from 370 to 1600 kg m- 3. Outside the plume, planktonic organisms increasingly contributed to the total volume concentration. Finally, we demonstrated the ability of gliders, equipped with optical backscattering sensors at several wavelengths, to describe the fine scale distributions of suspended particles, and provide an index of their size distribution.

  4. Baselines and Comparison of Coral Reef Fish Assemblages in the Central Red Sea

    KAUST Repository

    Kattan, Alexander

    2014-12-01

    In order to properly assess human impacts and appropriate restoration goals, baselines of pristine conditions on coral reefs are required. In Saudi Arabian waters of the central Red Sea, widespread and heavy fishing pressure has been ongoing for decades. To evaluate this influence, we surveyed the assemblage of offshore reef fishes in both this region as well as those of remote and largely unfished southern Sudan. At comparable latitudes, of similar oceanographic influence, and hosting the same array of species, the offshore reefs of southern Sudan provided an ideal location for comparison. We found that top predators (jacks, large snappers, groupers, and others) dominated the reef fish community biomass in Sudan’s deep south region, resulting in an inverted (top-heavy) biomass pyramid. In contrast, the Red Sea reefs of central Saudi Arabia exhibited the typical bottom-heavy pyramid and show evidence for trophic cascades in the form of mesopredator release. Biomass values from Sudan’s deep south are quite similar to those previously reported in the remote and uninhabited Northwest Hawaiian Islands, northern Line Islands, Pitcairn Islands, and other remote Pacific islands and atolls. The findings of this study suggest that heavy fishing pressure has significantly altered the fish community structure of Saudi Arabian Red Sea reefs. The results point towards the urgent need for enhanced regulation and enforcement of fishing practices in Saudi Arabia while simultaneously making a strong case for protection in the form of marine protected areas in the southern Sudanese Red Sea.

  5. Fungal Assemblages in Different Habitats in an Erman’s Birch Forest

    Science.gov (United States)

    Yang, Teng; Sun, Huaibo; Shen, Congcong; Chu, Haiyan

    2016-01-01

    Recent meta-analyses of fungal diversity using deeply sequenced marker genes suggest that most fungal taxa are locally distributed. However, little is known about the extent of overlap and niche partitions in total fungal communities or functional guilds within distinct habitats on a local forest scale. Here, we compared fungal communities in endosphere (leaf interior), phyllosphere (leaf interior and associated surface area) and soil samples from an Erman’s birch forest in Changbai Mountain, China. Community structures were significantly differentiated in terms of habitat, with soil having the highest fungal richness and phylogenetic diversity. Endophytic and phyllosphere fungi of Betula ermanii were more phylogenetically clustered compared with the corresponding soil fungi, indicating the ability of that host plants to filter and select their fungal partners. Furthermore, the majority of soil fungal taxa were soil specialists, while the dominant endosphere and phyllosphere taxa were aboveground generalists, with soil and plant foliage only sharing <8.2% fungal taxa. Most of the fungal taxa could be assigned to different functional guilds; however, the assigned guilds showed significant habitat specificity with variation in relative abundance. Collectively, the fungal assemblages in this Erman’s birch forest were strictly niche specialized and constrained by weak migration among habitats. The findings suggest that phylogenetic relatedness and functional guilds’ assignment can effectively interpret the certain ecological processes.

  6. Macroinvertebrate assemblages in agricultural, mining, and urban tropical streams: implications for conservation and management.

    Science.gov (United States)

    Mwedzi, Tongayi; Bere, Taurai; Mangadze, Tinotenda

    2016-06-01

    The study evaluated the response of macroinvertebrate assemblages to changes in water quality in different land-use settings in Manyame catchment, Zimbabwe. Four land-use categories were identified: forested commercial farming, communal farming, Great Dyke mining (GDM) and urban areas. Macroinvertebrate community structure and physicochemical variables data were collected in two seasons from 41 sites following standard methods. Although not environmentally threatening, urban and GDM areas were characterised by higher conductivity, total dissolved solids, salinity, magnesium and hardness. Chlorides, total phosphates, total nitrogen, calcium, potassium and sodium were significantly highest in urban sites whilst dissolved oxygen (DO) was significantly higher in the forested commercial faming and GDM sites. Macroinvertebrate communities followed the observed changes in water quality. Macroinvertebrates in urban sites indicated severe pollution (e.g. Chironomidae) whilst those in forested commercial farming sites and GDM sites indicated relatively clean water (e.g. Notonemouridae). Forested watersheds together with good farm management practices are important in mitigating impacts of urbanisation and agriculture. Strategies that reduce oxygen-depleting substances must be devised to protect the health of Zimbabwean streams. The study affirms the wider applicability of the South African Scoring System in different land uses. PMID:26920532

  7. Diversity and complexity complement apparent competition: Nematode assemblages in banana plantations

    Science.gov (United States)

    Ferris, Howard; Pocasangre, Luis E.; Serrano, Edgardo; Muñoz, Jorge; Garcia, Socorro; Perichi, Guillermo; Martinez, Gustavo

    2012-04-01

    The structure of communities of soil organisms, and, therefore, their ecosystem functions, respond to spatial and temporal changes in plant diversity and to subsidies of organic matter. We introduce the concept of amplifiable and target prey in directing the impact of shared predators on pest organisms. In soil nematode assemblages, rather than overt apparent competition between the two prey categories, the effects were more subtle and expressed as increased predation pressure on the target prey when resources for the amplifiable prey were greater. We conclude that the connectance complexity of the food web subverts resource flow through a sequential chain of trophic interactions so that interaction strength decreases at successive trophic exchange. However, the effect of resource diversion is that the net regulatory pressure on the target prey is potentially enhanced by the increase in alternate predators of each prey category. The system requires that certain criteria are met, including that predator populations are resource limited, that conditions are conducive for predator survival and increase, and that predators, amplifiable and target prey are co-located in a majority of patches associated with resource subsidy, favorable conditions or migration patterns.

  8. Visualization of species pairwise associations: a case study of surrogacy in bird assemblages.

    Science.gov (United States)

    Lane, Peter W; Lindenmayer, David B; Barton, Philip S; Blanchard, Wade; Westgate, Martin J

    2014-08-01

    Quantifying and visualizing species associations are important to many areas of ecology and conservation biology. Species networks are one way to analyze species associations, with a growing number of applications such as food webs, nesting webs, plant-animal mutualisms, and interlinked extinctions. We present a new method for assessing and visualizing patterns of co-occurrence of species. The method depicts interactions and associations in an analogous way with existing network diagrams for studying pollination and trophic interactions, but adds the assessment of sign, strength, and direction of the associations. This provides a distinct advantage over existing methods of quantifying and visualizing co-occurrence. We demonstrate the utility of our new approach by showing differences in associations among woodland bird species found in different habitats and by illustrating the way these can be interpreted in terms of underlying ecological mechanisms. Our new method is computationally feasible for large assemblages and provides readily interpretable effects with standard errors. It has wide applications for quantifying species associations within ecological communities, examining questions about particular species that occur with others, and how their associations can determine the structure and composition of communities. PMID:25473480

  9. Landscape properties mediate the homogenization of bird assemblages during climatic extremes.

    Science.gov (United States)

    Haslem, Angie; Nimmo, Dale G; Radford, James Q; Bennett, Andrew F

    2015-12-01

    Extreme weather events, such as drought, have marked impacts on biotic communities. In many regions, a predicted increase in occurrence of such events will be imposed on landscapes already heavily modified by human land use. There is an urgency, therefore, to understand the way in which the effects of such events may be exacerbated, or moderated, by different patterns of landscape change. We used empirical data on woodland-dependent birds in southeast Australia, collected during and after a severe drought, to document temporal change in the composition of bird assemblages in 24 landscapes (each 100 km2) representing a gradient in the cover of native wooded vegetation (from 60% to drought caused region-wide homogenization of the composition of landscape bird assemblages, and (b) whether landscape properties influenced the way assemblages changed in response to drought. To quantify change, we used pairwise indices of assemblage dissimilarity, partitioned into components that represented change in the richness of assemblages and change in the identity of constituent species (turnover). There was widespread loss of woodland birds in response to drought, with only partial recovery following drought-breaking rains. Region-wide, the composition of landscape assemblages became more different over time, primarily caused by turnover-related differentiation. The response of bird assemblages to drought varied between landscapes and was strongly associated with landscape properties. The extent of wooded vegetation had the greatest influence on assemblage change: landscapes with more native vegetation had more stable bird assemblages over time. However, for the component processes of richness- and turnover-related compositional change, measures of landscape productivity had a stronger effect. For example, landscapes with more riparian vegetation maintained more stable assemblages in terms of richness. These results emphasize the importance of the total extent of native

  10. The zoonotic potential of Giardia intestinalis assemblage E in rural settings.

    Science.gov (United States)

    Abdel-Moein, Khaled A; Saeed, Hossam

    2016-08-01

    Giardiasis is a globally re-emerging protozoan disease with veterinary and public health implications. The current study was carried out to investigate the zoonotic potential of livestock-specific assemblage E in rural settings. For this purpose, a total of 40 microscopically positive Giardia stool samples from children with gastrointestinal complaints with or without diarrhea were enrolled in the study as well as fecal samples from 46 diarrheic cattle (18 dairy cows and 28 calves). Animal samples were examined by sedimentation method to identify Giardia spp., and then, all Giardia positive samples from human and animals were processed for molecular detection of livestock-specific assemblage E through amplification of assemblage-specific triosephosphate isomerase (tpi) gene using nested polymerase chain reaction (PCR). The results of the study revealed high unexpected occurrence of assemblage E among human samples (62.5 %), whereas the distribution among patients with diarrhea and those without was 42.1 and 81 %, respectively. On the other hand, the prevalence of Giardia spp. among diarrheic dairy cattle was (8.7 %), while only calves yielded positive results (14.3 %) and all bovine Giardia spp. were genetically classified as Giardia intestinalis assemblage E. Moreover, DNA sequencing of randomly selected one positive human sample and another bovine one revealed 100 and 99 % identity with assemblage E tpi gene sequences available at GenBank after BLAST analysis. In conclusion, the current study highlights the wide dissemination of livestock-specific assemblage E among humans in rural areas, and thus, zoonotic transmission cycle should not be discounted during the control of giardiasis in such settings. PMID:27112756

  11. Fish assemblages of the Casiquiare River, a corridor and zoogeographical filter for dispersal between the Orinoco and Amazon basins

    Science.gov (United States)

    Winemiller, K.O.; Lopez-Fernandez, H.; Taphorn, D.C.; Nico, L.G.; Duque, A.B.

    2008-01-01

    (bifurcation of the Orinoco) and blackwater conditions nearer to its mouth (junction with the Rio Negro). The second CCA axis was most strongly associated with habitat size and structural complexity. Species associations derived from the unweighted pair-group average clustering method and pair-wise squared Euclidean distances calculated from species loadings on CCA axes 1 and 2 showed seven ecological groupings. Cluster analysis of species assemblages according to watershed revealed a stronger influence of local environmental conditions than of geographical proximity. Main conclusions: Fish assemblage composition is more consistently associated with local environmental conditions than with geographical position within the river drainages. Nonetheless, the results support the hypothesis that the mainstem Casiquiare represents a hydrochemical gradient between clearwaters at its origin and blackwaters at its mouth, and as such appears to function as a semi-permeable barrier (environmental filter) to dispersal and faunal exchanges between the partially vicariant fish faunas of the Upper Orinoco and Upper Negro rivers. ?? 2008 The Authors.

  12. Influence of the invasive Asian clam Corbicula fluminea (Bivalvia: Corbiculidae) on estuarine epibenthic assemblages

    Science.gov (United States)

    Ilarri, M. I.; Souza, A. T.; Antunes, C.; Guilhermino, L.; Sousa, R.

    2014-04-01

    One of the most widespread invasive alien species (IAS) in aquatic ecosystems is the Asian clam Corbicula fluminea. Several studies have shown that C. fluminea can cause large-scale changes in macrozoobenthic assemblages; however, very few attempted to investigate the effects of this IAS on mobile epibenthic species, such as fishes and crustaceans. In this context, the influence of C. fluminea on epibenthic species was investigated during one year by comparing the associated epibenthic fauna in three nearby sites of the Minho estuary (NW of the Iberian Peninsula), wherein the abiotic conditions are similar but the density of the Asian clam is highly different. From a total of 13 species, six were significantly influenced by C. fluminea; five responded positively, namely the brown shrimp Crangon crangon, the European eel Anguilla anguilla, the common goby Pomatoschistus microps, the brown trout Salmo trutta fario and the great pipefish Syngnathus acus, whereas the shore crab Carcinus maenas was negatively influenced. However, stomach contents analysis revealed that fish and crustacean species do not feed on C. fluminea, suggesting that this IAS is still not a large component of the diet of higher trophic levels in this estuarine ecosystem. Our results suggest that the structure provided by C. fluminea shells is likely to be one of the main factors responsible for the differences observed. C. fluminea physical structure seems to influence the epibenthic associated fauna, when found in densities higher than 1000 ind./m2, with sedentary small-bodied crustaceans and fishes being mainly attracted by the increasing in habitat complexity and consequent enhancement of heterogeneity and shelter availability.

  13. The assemblage characteristics of benthic macroinvertebrates in the Yalutsangpo River, the highest major river in the world

    Science.gov (United States)

    Xu, Mengzhen; Wang, Zhaoyin; Pan, Baozhu; Yu, Guoan

    2014-09-01

    regional biodiversity. The ordination diagram obtained from Detrended Correspondence Analysis indicated that altitude, river pattern, riverbed structures, bank structures, and flow conditions were the main factors that influenced the macroinvertebrate assemblages in the Yalutsangpo basin.

  14. Multilocus genotyping of human Giardia isolates suggests limited zoonotic transmission and association between assemblage B and flatulence in children

    OpenAIRE

    Lebbad, M.; Petersson, I.; Karlsson, L.; Botero-Kleiven, S; Andersson, JO; Svenungsson, B; Svärd, SG

    2011-01-01

    BACKGROUND: Giardia intestinalis is one of the most common diarrhea-related parasites in humans, where infection ranges from asymptomatic to acute or chronic disease. G. intestinalis consists of eight genetically distinct genotypes or assemblages, designated A-H, and assemblages A and B can infect humans. Giardiasis has been classified as a possible zoonotic disease but the role of animals in human disease transmission still needs to be proven. We tried to link different assemblages and sub-a...

  15. The behavior of iron in (Mg,Fe)SiO3 post-perovskite assemblages at Mbar pressures

    International Nuclear Information System (INIS)

    The electronic environment of the iron sites in post-perovskite (PPv) structured (57Fe,Mg)SiO3 has been measured in-situ at 1.12 and 1.19 Mbar at room temperature using 57Fe synchrotron Moessbauer spectroscopy. Evaluation of the time spectra reveals two distinct iron sites, which are well distinguished by their hyperfine fields. The dominant site is consistent with an Fe3+-like site in a high spin state. The second site is characterized by a small negative isomer shift with respect to α-iron and no quadrupole splitting, consistent with a metallic iron phase. Combined with SEM/EDS analyses of the quenched assemblage, our results are consistent with the presence of a metallic iron phase co-existing with a ferric-rich PPv. Such a reaction pathway may aid in our understanding of the chemical evolution of Earth's core-mantle-boundary region.

  16. Behavior of iron in (Mg,Fe)SiO3 post-perovskite assemblages at Mbar pressures

    International Nuclear Information System (INIS)

    The electronic environment of the iron sites in postperovskite (PPv) structured (57Fe,Mg)SiO3 has been measured in-situ at 1.12 and 1.19 Mbar at room temperature using 57Fe synchrotron Moessbauer spectroscopy. Evaluation of the time spectra reveals two distinct iron sites, which are well distinguished by their hyperfine fields. The dominant site is consistent with an Fe3+-like site in a high spin state. The second site is characterized by a small negative isomer shift with respect to α-iron and no quadrupole splitting, consistent with a metallic iron phase. Combined with SEM/ EDS analyses of the quenched assemblage, our results are consistent with the presence of a metallic iron phase coexisting with a ferric-rich PPv. Such a reaction pathway may aid in our understanding of the chemical evolution of Earth's core-mantle-boundary region.

  17. Avian Assemblages at Bird Baths: A Comparison of Urban and Rural Bird Baths in Australia.

    Directory of Open Access Journals (Sweden)

    Gráinne P Cleary

    Full Text Available Private gardens provide habitat and resources for many birds living in human-dominated landscapes. While wild bird feeding is recognised as one of the most popular forms of human-wildlife interaction, almost nothing is known about the use of bird baths. This citizen science initiative explores avian assemblages at bird baths in private gardens in south-eastern Australia and how this differs with respect to levels of urbanisation and bioregion. Overall, 992 citizen scientists collected data over two, four-week survey periods during winter 2014 and summer 2015 (43% participated in both years. Avian assemblages at urban and rural bird baths differed between bioregions with aggressive nectar-eating species influenced the avian assemblages visiting urban bird baths in South Eastern Queensland, NSW North Coast and Sydney Basin while introduced birds contributed to differences in South Western Slopes, Southern Volcanic Plains and Victorian Midlands. Small honeyeaters and other small native birds occurred less often at urban bird baths compared to rural bird baths. Our results suggest that differences between urban versus rural areas, as well as bioregion, significantly influence the composition of avian assemblages visiting bird baths in private gardens. We also demonstrate that citizen science monitoring of fixed survey sites such as bird baths is a useful tool in understanding large-scale patterns in avian assemblages which requires a vast amount of data to be collected across broad areas.

  18. Megafloral assemblage similar to Karharbari biozone from Talchir Coalfield of Mahanadi Basin, Orissa

    Energy Technology Data Exchange (ETDEWEB)

    Singh, K.J.; Goswami, S.; Chandra, S. [Birbal Sahni Institute of Paleobotany, Lucknow (India)

    2006-08-15

    A rich collection of plant megafossils have been studied from the rocks of Karharbari Formation (Early Permian=Lower Artinskian) at South Balanda Colliery (Latitude 20 degrees 56' Longitude 85 degrees 14'), Talchir Coalfield, Angul district, Orissa. The lower Gondwana rocks in this coalfield have been represented by Talchir, Karharbari, Barakar, Barren Measures and the Kamthi Formations (in ascending order) representing earliest Permian to Late Permian. Palaeobotanical studies have been extensively carried out in the past by a number of workers in almost all the Lower Gondwana formations except the Karharbari Formation. Megafloral assemblage has been recovered for the first time from Karharbari sediments of the Lower Gondwana deposits in this coalfield. The specimens are preserved as impressions and compressions on blackish grey fine-grained shales of the South Balanda Colliery exposed just above the carbonaceous shales. The lowermost coal seam i.e. seam no. 1/Karharbari seam of this coalfield exists below the above-mentioned two shale bands. The megafloral assemblage consists of Phyllotheca westensis, Noeggerathiopsis hislopii, Euryphyllum whittianum, E. maithyi, Macrotaeniopteris feddeni, Buriadia heterophylla, Glossopteris browniana, G. communis, Gangamopteris cyclopleroides and Surangephyllum elongatum. The genus Buriadia dominates the total assemblage (about 80%). The assemblage has been compared thoroughly with the known megafloral assemblages of Karharbari Formation.

  19. Environmental changes and shallow marine fossil bivalve assemblages of the Lower Cretaceous Miyako Group, NE Japan

    Science.gov (United States)

    Fujino, Shigehiro; Maeda, Haruyoshi

    2013-03-01

    We reconstructed the environmental changes recorded in the Lower Cretaceous Miyako Group via facies analysis and delineated the relationship between depositional facies and the occurrence of diverse marine invertebrate macrofossils. The Miyako Group consists of deposits from alluvial bay-head delta, bay-head delta front, central bay, and lower shoreface to inner shelf depositional settings. Fossil bivalve assemblages responded to shifts in these sedimentary environments. We defined three fossil bivalve assemblages from the central bay and lower shoreface to inner shelf deposits. The assemblages in the inner shelf and central bay deposits are clearly different, even though they occur within similar depositional facies. This contrast in assemblages results from environmental differences between closed and open settings; this interpretation is supported by the occurrence of stenohaline crinoids. We defined a fourth bivalve assemblage in a tsunami deposit intercalated within the bay-head delta front deposits. It consists of polygenic allochthonous shells, some that were derived from an estuarine environment or the shallow seafloor and others that were torn from small reefs.

  20. Avian Assemblages at Bird Baths: A Comparison of Urban and Rural Bird Baths in Australia.

    Science.gov (United States)

    Cleary, Gráinne P; Parsons, Holly; Davis, Adrian; Coleman, Bill R; Jones, Darryl N; Miller, Kelly K; Weston, Michael A

    2016-01-01

    Private gardens provide habitat and resources for many birds living in human-dominated landscapes. While wild bird feeding is recognised as one of the most popular forms of human-wildlife interaction, almost nothing is known about the use of bird baths. This citizen science initiative explores avian assemblages at bird baths in private gardens in south-eastern Australia and how this differs with respect to levels of urbanisation and bioregion. Overall, 992 citizen scientists collected data over two, four-week survey periods during winter 2014 and summer 2015 (43% participated in both years). Avian assemblages at urban and rural bird baths differed between bioregions with aggressive nectar-eating species influenced the avian assemblages visiting urban bird baths in South Eastern Queensland, NSW North Coast and Sydney Basin while introduced birds contributed to differences in South Western Slopes, Southern Volcanic Plains and Victorian Midlands. Small honeyeaters and other small native birds occurred less often at urban bird baths compared to rural bird baths. Our results suggest that differences between urban versus rural areas, as well as bioregion, significantly influence the composition of avian assemblages visiting bird baths in private gardens. We also demonstrate that citizen science monitoring of fixed survey sites such as bird baths is a useful tool in understanding large-scale patterns in avian assemblages which requires a vast amount of data to be collected across broad areas. PMID:26962857

  1. Floral neighborhood influences pollinator assemblages and effective pollination in a native plant.

    Science.gov (United States)

    Bruckman, Daniela; Campbell, Diane R

    2014-10-01

    Pollinators represent an important intermediary by which different plant species can influence each other's reproductive fitness. Floral neighbors can modify the quantity of pollinator visits to a focal species but may also influence the composition of visitor assemblages that plants receive leading to potential changes in the average effectiveness of floral visits. We explored how the heterospecific floral neighborhood (abundance of native and non-native heterospecific plants within 2 m × 2 m) affects pollinator visitation and composition of pollinator assemblages for a native plant, Phacelia parryi. The relative effectiveness of different insect visitors was also assessed to interpret the potential effects on plant fitness of shifts in pollinator assemblage composition. Although the common non-native Brassica nigra did not have a significant effect on overall pollinator visitation rate to P. parryi, the proportion of flower visits that were made by native pollinators increased with increasing abundance of heterospecific plant species in the floral neighborhood other than B. nigra. Furthermore, native pollinators deposited twice as many P. parryi pollen grains per visit as did the nonnative Apis mellifera, and visits by native bees also resulted in more seeds than visits by A. mellifera. These results indicate that the floral neighborhood can influence the composition of pollinator assemblages that visit a native plant and that changes in local flower communities have the potential to affect plant reproductive success through shifts in these assemblages towards less effective pollinators. PMID:25047026

  2. Do diel variations in stream fish assemblages depend on spatial positioning of the sampling sites?

    Directory of Open Access Journals (Sweden)

    István Czeglédi

    2015-12-01

    Full Text Available The effect of diel period (i.e. day vs. night and its dependence on the spatial position of the sampling site were evaluated on the assessment of fish assemblage attributes in a wadeable lowland stream (Hajagos stream, Hungary. Species richness, composition and abundance data of two 150 m long reaches, of which one situated directly at the tributary mouth and one 6 km upstream were compared using three pass removal by electrofishing in three seasons (summer, autumn, spring to test the effect of spatial position on day and night patterns. No differences in any assemblage level variables were found between day and night. Although fish assemblages showed large temporal variations, spatial position of the sampling site had the most influential effect on fish assemblage attributes compared with seasonal and/or day night patterns. Consequently, the diel period had rather negligible effect in the studied stream. Daytime electrofishing data seems to be highly representative for the accurate assessment of fish assemblages in relatively small (less than 5 m wide wadeable streams and maybe used reliably for any model of community organization (e.g. food web studies.

  3. Spatial and seasonal patterns of ichthyoplankton assemblages in the Haizhou Bay and its adjacent waters of China

    Science.gov (United States)

    Li, Zengguang; Ye, Zhenjiang; Wan, Rong

    2015-12-01

    Surveys were conducted in five voyages in Haizhou Bay and its adjacent coastal area from March to December 2011 during full moon spring tides. The ichthyoplankton assemblages and the environmental factors that affect their spatial and seasonal patterns were determined. Totally 35 and 12 fish egg and larvae taxa were identified, respectively. Over the past several decades, the egg and larval species composition has significantly changed in Haizhou Bay and its adjacent waters, most likely corresponding with the alteration of fishery resources, which are strongly affected by anthropogenic activities and climate change. The Bray-Curtis dissimilarity index identified four assemblages: near-shore bay assemblage, middle bay assemblage and two closely related assemblages (near-shore/middle bay assemblage and middle/edge of bay assemblage). The primary species of each assemblage principally reflected the spawning strategies of adult fish. The near-shore bay assemblage generally occurred in near-shore bay, with depths measuring biological behavioral traits and oceanographic features, particularly the variation of local conditions within the constraint of a general reproductive strategy. The results of Spearman's rank correlation analysis indicated that both fish egg and larval abundance were positively correlated with depth, which is critical to the oceanographic features in Haizhou Bay.

  4. Disease outbreaks, bleaching and a cyclone drive changes in coral assemblages on an inshore reef of the Great Barrier Reef

    Science.gov (United States)

    Haapkylä, J.; Melbourne-Thomas, J.; Flavell, M.; Willis, B. L.

    2013-09-01

    Coral disease is a major threat to the resilience of coral reefs; thus, understanding linkages between disease outbreaks and disturbances pre