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Sample records for benthic foraminiferal assemblages

  1. Recent benthic foraminiferal assemblages from cold-water coral mounds in the porcupine seabight

    OpenAIRE

    Schönfeld, Joachim; Dullo, Wolf-Christian; Pfannkuche, Olaf; Freiwald, André; Rüggeberg, Andres; Schmidt, Steffi; Weston, Janice

    2011-01-01

    Cold-water coral ecosystems are characterised by a high diversity and population density. Living and dead foraminiferal assemblages from 20 surface sediment samples from Galway and Propeller Mounds were analysed to describe the distribution patterns of benthic foraminifera on coral mounds in relation to different sedimentary facies. Hard substrates were examined to assess the foraminiferal microhabitats and diversities in the coral framework. We recognised 131 different species, of which 27 p...

  2. Benthic foraminiferal assemblage formation: Theory and observation for the European Arctic margin

    Science.gov (United States)

    Loubere, Paul; Rayray, Shan

    2016-09-01

    We use theory and observation to determine how benthic foraminiferal populations living in a range of sedimentary microenvironments are translated into fossil assemblages along the continental margin of the European Arctic. We examine downcore stained (cell tracker green and rose Bengal) and total species shell abundances through the sediment mixing (bioturbation) zone. This, in combination with porewater geochemical measurements, allows us to establish zones of production and destruction for species' shells, and deduce how the fossil record is being generated by the living community. For many taxa, shell production is high in the upper, oxic, sedimentary layer, but destruction in this zone is also high. Hence, contribution to the fossil record is biased to more infaunal populations and species. Taxa producing near, or below, the anoxic boundary of the sediments are particularly important to the developing fossil record of the fjord environment. We find that taxon relative and absolute abundances change continuously through the biologically active sediment profile. This has implications for reconstructing paleoenvironments using benthic foraminiferal assemblages, and potentially for the geochemistry of individual fossil taxa.

  3. Effectiveness of benthic foraminiferal and coral assemblages as water quality indicators on inshore reefs of the Great Barrier Reef, Australia

    Science.gov (United States)

    Uthicke, S.; Thompson, A.; Schaffelke, B.

    2010-03-01

    Although the debate about coral reef decline focuses on global disturbances (e.g., increasing temperatures and acidification), local stressors (nutrient runoff and overfishing) continue to affect reef health and resilience. The effectiveness of foraminiferal and hard-coral assemblages as indicators of changes in water quality was assessed on 27 inshore reefs along the Great Barrier Reef. Environmental variables (i.e., several water quality and sediment parameters) and the composition of both benthic foraminiferal and hard-coral assemblages differed significantly between four regions (Whitsunday, Burdekin, Fitzroy, and the Wet Tropics). Grain size and organic carbon and nitrogen content of sediments, and a composite water column parameter (based on turbidity and concentrations of particulate matter) explained a significant amount of variation in the data (tested by redundancy analyses) in both assemblages. Heterotrophic species of foraminifera were dominant in sediments with high organic content and in localities with low light availability, whereas symbiont-bearing mixotrophic species were dominant elsewhere. A similar suite of parameters explained 89% of the variation in the FORAM index (a Caribbean coral reef health indicator) and 61% in foraminiferal species richness. Coral richness was not related to environmental setting. Coral assemblages varied in response to environmental variables, but were strongly shaped by acute disturbances (e.g., cyclones, Acanthaster planci outbreaks, and bleaching), thus different coral assemblages may be found at sites with the same environmental conditions. Disturbances also affect foraminiferal assemblages, but they appeared to recover more rapidly than corals. Foraminiferal assemblages are effective bioindicators of turbidity/light regimes and organic enrichment of sediments on coral reefs.

  4. Assessing environmental impact from gas and oil exploration in the SW Barents Sea using benthic foraminiferal assemblages

    Science.gov (United States)

    Dijkstra, N.; Junttila, J.; Husum, K.; Carroll, J.; Hald, M.

    2012-04-01

    During the last decades petroleum industry and shipping activities have increased in the SW Barents Sea. Oil exploration wells were drilled in the 1980s with production starting in 2007. These activities are projected to expand in the coming years. As part of the Northern Environmental Waste Management (EWMA) project, a competence cluster for petroleum industry related waste handling, we investigate the impacts of enhanced anthropogenic activities on benthic foraminiferal assemblages in the SW Barents Sea. Sediment cores (0-20 cm) from sites in proximity to two oil- and gas fields are under investigation. These sediment cores, dated with the 210Pb method, represent the last 90 to 150 years. Both dead and living benthic foraminifera (100 µm-1 mm) were counted to elucidate differences in foraminiferal assemblages between pre-impact and recent conditions. In addition, the heavy metal concentrations, persistent organic pollutant (POP) concentrations, grain size and total organic content (TOC) of the sediment cores have been analyzed. Pollution levels of the surface sediments (0-1 cm) are of background to good level (level I-II) according to the definitions of the Water Framework Directorate (WFD). Patterns in living benthic foraminiferal assemblages identified in the sea floor surface sediments, are the result of natural environmental changes such as depth, water mass and sediment composition. Further downcore (1-20 cm) pollution levels are in general of background environmental status (WFD level I). However, at some depth intervals, especially in sediment cores from the near proximity of the oil- and gas- fields, pollution levels are slightly enhanced (WFD level II). Further work will include statistical comparison of dead and living foraminiferal assemblages with sediment pollution levels, sediment properties, and oceanographic conditions. This research contributes to the development of foraminifera as a useful bio-monitoring technique for the Arctic region as

  5. Eocene benthic foraminiferal assemblages from Central Anatolia (Turkey): Biostratigraphy, stable isotope data, paleoenvironmental and paleontological interpretations

    Science.gov (United States)

    Dinçer, Feyza

    2016-02-01

    Stable isotope (δ13C and δ18O) values from Eocene aged shallow marine deposits in two different basins (Haymana and Kırşehir-Kaman) of Central Anatolia and benthic foraminiferal biostratigraphy's corresponding sequences were analyzed to determine paleontological and paleoenvironmental changes. The shallow marine units (Çayraz and Altıpınar formations), deposited as a result of different geological processes in the same period, show differences in paleontological and geochemical properties of the tests. The geological process controlled by environmental factors affect the formation of the chemical structure of foraminiferal calcite. These Lutetian and Bartonian aged formations are represented by five Shallow Benthic Zones. While, the Çayraz section is represented by SBZ 14-18, Boztepe section is represented by SBZ 13-17. With an increase in temperature, the variety of benthic foraminifera decreased, and Assilina exponens became the dominant species in the warm conditions. The most important proxy is δ13C, which reflects the paleoproductivity (food supply) where benthic foraminifera lived. In addition, food supply can be considered to be a more important factor than temperature, as it controls the diversity and abundance of benthic foraminifera.

  6. Last glacial to Holocene productivity and oxygen changes based on benthic foraminiferal assemblages from the western Alboran Sea

    Science.gov (United States)

    Pérez-Asensio, José N.; Cacho, Isabel; Frigola, Jaime; Pena, Leopoldo D.; Asioli, Alessandra; Kuhlmann, Jannis; Huhn, Katrin

    2016-04-01

    Late glacial to Holocene productivity and oxygen changes in the Alboran Sea were investigated analyzing benthic foraminiferal assemblages from the marine sediment core HER-GC-UB06. This 255 cm-long core was recovered at 946 m water depth in the Alboran Sea (western Mediterranean Sea) and includes homogeneous greyish clays from the last 23 ka. Nowadays, the core site is bathed by the Western Mediterranean Deep Water (WMDW) and near the overlying Levantine Intermediate Water (LIW). Benthic foraminifera from the size fraction >63 μm were identified at species level and counted until reaching at least 300 individuals. Q-mode principal component analyses (PCA) was performed to establish benthic foraminiferal assemblages. In addition, benthic foraminifera were classified according to their microhabitat preferences. Diversity was assessed with several diversity indices. Four benthic foraminiferal assemblages have been identified along the core. The distribution of these assemblages records changes in productivity and oxygen conditions during the last 23 ka. The last glacial and deglaciation interval, 23-12.5 ka, shows low diversity and is characterized by the Nonionella iridea assemblage, which includes Cassidulina laevigata, Bolivina dilatata, Nonionoides turgida and Cibicides pachyderma as secondary taxa. This assemblage can be interpreted as a moderately oxygenated mesotrophic environment with episodic pulses of fresh organic matter. Although general mesotrophic conditions prevail, the Last Glacial Maximum shows a more oligotrophic and better oxygenated setting as suggested by higher abundance of epifaunal-shallow infaunal taxa. In contrast, along the Bølling-Allerød eutrophic conditions with higher productivity and lower oxygenation are recorded by a deep infaunal taxa maximum. During the Younger Dryas (YD) and the earliest Holocene (12.5-10.5 ka), the Bolivina dilatata assemblage dominates coinciding with a lower diversity, especially during the YD. This species

  7. SHE analysis for biozonation of benthic foraminiferal assemblages from western arctic ocean

    Science.gov (United States)

    Osterman, L.E.; Buzas, M.A.; Hayek, L.-A.C.

    2002-01-01

    Benthic foraminiferal species abundance in samples from three Mendeleyev Ridge box cores were analyzed by cluster analysis and the newer method of SHE analysis. Previously, the latter technique only has been used on foraminiferal data from depth transects of modern surface sediment samples. Unlike most methods, which initially compare all possible pairs of samples, the SHE procedure results in a linear pattern if a sequence of samples are from the same statistical distribution. A change in slope indicates a statistical change in community structure and / or a change in species composition. The research reported herein is the first application of SHE for the purpose of identifying biozones in sediment core samples for the purpose of stratigraphic correlation. Both cluster analysis and the SHE method provided zonation within cores. However, the cluster method often produced clusters that were difficult to identify and also contained a mixture of samples without stratigraphic continuity. In contrast, SHE resulted in easily identifiable biozones and ensured temporal continuity within them. In general, the cluster analysis produced more zones than the SHE analysis. About 87% of the cluster zones and 64% of the SHE zones were correlated across more than one core. The average age range for correlated biozone boundaries among the three cores, based on radiocarbon dates, was 821 years using cluster analysis and 296 years using SHE. The sequential nature of the analysis, ease in choosing boundaries, and correlation of these boundaries across cores makes SHE the preferred technique.

  8. Late Pleistocene-Holocene events on the continental slope of the Laptev Sea: Evidence from benthic and planktonic foraminiferal assemblages

    Science.gov (United States)

    Ovsepyan, Ya. S.; Taldenkova, E. E.; Bauch, H. A.; Kandiano, E. S.

    2015-11-01

    This work is dedicated to the study of benthic and planktonic foraminifers and is a contribution to the multidisciplinary investigations of Core PS51/154-11 from the Laptev Sea. The paleoecological analysis of foraminiferal assemblages makes it possible to reconstruct in detail environmental changes on the western continental margin of the Laptev Sea during the Late Pleistocene and Holocene. The examined core dated by the AMS radiocarbon method is divided into intervals that reflect main stages in the regional evolution for the last 17.6 k.y.: early deglaciation, Bølling-Allerød warming, Younger Dryas cooling, transition to the Interglacial, Holocene climatic optimum, Middle-Late Holocene. The presence of subpolar planktonic foraminifers and benthic species Cassidulina neoteretis (Tappan) provides grounds to reconstruct for the continental slope area stages of the enhanced activity of subsurface Atlantic-derived water in the intervals of 12.0-14.7 and 0.6-5.4 ka. The benthic assemblage reflects changes in depositional environments related to the postglacial transgression and also climatic change impacts affecting bioproductivity. The events defined on the basis of foraminifers are correlated with climatic oscillations and changes in circulation of water masses.

  9. Benthic foraminiferal assemblages as potential ecological proxies for environmental monitoring in coastal sediment of the Port Klang, Selangor

    Science.gov (United States)

    Chandran, Ravindran; Omar, Ramlan; Leman, Mohd Shafeea; Faiz, Noraswana Nor

    2015-09-01

    This study represents the benthic foraminiferal assemblages, distribution and its composition along the coastal water of Port Klang, Malaysia. A total of 60 samples were collected bimonthly between Jun 2013 and July 2013 at four sites (i.e. West Port, North Port, South Port, Telok Gong and Klang River). There were 20 genera of foraminifera identified from this study sites namely: Acupeina, Ammobaculites, Ammonia, Ammotium, Arenoparella, Asterorotalia, Bolivina, Cibicides,Discorbis, Elphidium, Haplophragmoides, Haynesina, Lagena, Miliammina, Nonion, Pseudorotalia, Quinqueloculina, Spiroloculina, Textularia and Trochammina. The foraminiferal assemblages at West Port was low in diversity (H'=0.58)compared to other sites and low in abundance (804 individuals). Stress tolerant taxa, Ammonia (317 individuals) dominated the distribution in West Port. However, in North Port, high foraminifera diversity (H'=0.67) was noted compared to West Port but lower than Telok Gong and Klang river. Foraminifera at North Port very low in abundance (213 individuals). High Ammonia-Elphidium Index (AEI) value (95) and low FORAM Index (FI=1.04) recorded at South Port indicating the sediments impacted by anthropogenic stressor and therefore the sediments were in hypoxic condition. Higher FORAM Index (F1=2.34) at North Port indicated less human induced activities in the area. There were high density of foraminifera (8918 individuals) and high AEI index value (83) with high Foram Index (F1=1.11) at Telok Gong compared to other sites except North Port. The same results were recorded at Klang River locations which covered 15 sampling stations with high abundance of Ammonia spp indicating disturbed environments. Lower abundance of Elphidium spp in contrast to Ammonia spp suggests that the sediments in all the sampling sites are in hypoxic condition and less oxygen concentrations.

  10. Western Indian Ocean circulation and climate variability on different time scales. A study based on stable oxygen and carbon isotopes, benthic foraminiferal assemblages and Mg/Ca paleothermometry

    Energy Technology Data Exchange (ETDEWEB)

    Romahn, Sarah

    2014-08-19

    In order to understand the Earth's climate evolution it is crucial to evaluate the role of low-latitude oceans in the global climate system, as they are connected to both hemispheres via atmospheric and oceanic circulation and thus hold the potential to disentangle the asynchronicity of short-term Pleistocene climate variability. However, the potential of low latitude oceans to respond to and force large-scale changes of the climate system is still debated. The aim of this thesis is to examine and to understand the causal relationship of both atmospheric and oceanic changes in the tropical western Indian Ocean on centennial-, millennial and glacial-interglacial timescales. For this purpose I investigated stable oxygen and carbon isotope compositions of both planktic and benthic foraminiferal tests, Mg/Ca ratios of planktic foraminiferal tests as well as benthic foraminiferal assemblages and sedimentary geochemical parameters on two sediment cores (GeoB12615-4, 446 m and GeoB12616-4, 1449 m) from the continental slope off Tanzania, East Africa.

  11. Deep-sea trace fossil and benthic foraminiferal assemblages across glacial Terminations 1, 2 and 4 at the "Shackleton Site" (IODP Expedition 339, Site U1385)

    Science.gov (United States)

    Rodríguez-Tovar, Francisco J.; Dorador, Javier; Grunert, Patrick; Hodell, David

    2015-10-01

    Numerous studies focused on the transitions between glacial and interglacial periods, the so-called terminations, due to the associated significant reorganizations of the ocean-atmosphere system. However, analyses combining macro- and micropaleontological information are near absent. In this research, an integrative study of trace fossils and benthic foraminiferal assemblages is conducted in order to improve the characterization of Terminations 1, 2 and 4, as revealing the response of the macro-and microbenthic habitats to the involved paleoenvironmental changes. For this purpose, selected cores from Site U1385 (IODP Expedition 339) located off the western Iberian Margin, have been studied. Changes in trace fossils and benthic foraminifera related to both long-term variations at the glacial/interglacial scale, and short-term millennial-scale climatic events. Food and oxygen availability have been identified as the main factors determining variations in the macro- and microbenthic community structure across glacial terminations in the context of changes in water mass distribution and productivity in the NE Atlantic. A deep-sea multi-tiered tracemaker community, consisting of biodeformational structures, Chondrites, ?Nereites, Palaeophycus, Planolites, Thalassinoides, and Zoophycos, suggest generally well-oxygenated bottom and pore-water conditions during interglacial as well as glacial intervals, with punctual decreases in oxygenation. Short-climatic events registered during Terminations 1, 2, and 4 induce a similar response of trace fossil and benthic foraminifera communities to the variable incidence of food and oxygen availability. Termination 1 shows a severe deterioration of oxic conditions and increasing food availability during the YD and HS 1, favoring appearance/dominance of Zoophycos, together with the lowest miliolid and the highest deep infaunal taxa abundances. Short-term climatic events (HS 11, IRE 10.1) associated with Terminations 2 and 4 are

  12. Benthic foraminiferal distribution in surface sediments along continental slope of the southern Okinawa Trough:dependance on water masses and food supply

    Institute of Scientific and Technical Information of China (English)

    向荣; 李铁刚; 杨作升; 阎军; 曹奇原

    2003-01-01

    Benthic foraminiferal analysis of 29 samples in surface sediments from the southern Oki-nawa Trough is carried out. The results indicate that benthic foraminiferal abundance decreases rapidlywith increasing water depth. Percentage frequencies of agglutinated foraminifera further confirm themodem shallow carbonate lysocline in the southern Okinawa Trough. From continental shelf edge to thebottom of Okinawa Trough, benthic foraminiferal fauna in the surface sediments can be divided into 5assemblages: (1) Continental shelf break assemblage, dominated by Cibicides pseudoungerianus, corre-sponds to subsurface water mass of the Kuroshio Current; (2) upper continental slope assemblage, domi-nated by Cassidulina carinata, Globocassidulina subglobosa, corresponds to intermediate water mass of the Kuroshio Current; (3) intermediate continental slope assemblage, dominated by Uvigerina hispi-da, corresponds to the Okinawa Trough deep water mass above the carbonate lysocline; (4) lower con-tinental slope- trough bottom assemblage, dominated by Pullenia bulloides, Epistominella exigua andCibicidoides hyalinus, corresponds to deep water mass of the Okinawa Trough; and (5) trough bottomagglutinated assemblage, dominated by Rhabdammina spp., Bathysiphon flavidus, corresponds tostrongly dissolved environment of the trough bottom. The benthic foraminiferal fauna in the southemOkinawa Trough are controlled jointly by water masses and food supply. Water temperature, oxygenconcentration and carbonate dissolution of the water masses are important controlling factors especiallyfor the continental shelf break and trough bottom assemblages. The food supply also plays an importantrole in these benthic foraminiferal assemblages along the westem slope of the Okinawa Trough. Both theabundance and the 5 assemblages of benthic foraminifera correspond well to the organic matter supplyalong the continental slope and a lateral transport of TSM (total suspended matter) and POC (particulateorganic

  13. Planktonic and benthic foraminiferal biostratigraphy of the Middle Eocene-Lower Miocene successions from the Sivas Basin (Central Anatolia, Turkey)

    Science.gov (United States)

    Hakyemez, Aynur; Özgen-Erdem, Nazire; Kangal, Özgen

    2016-02-01

    Planktonic and benthic foraminifera are described from the Middle Eocene-Lower Miocene successions in the Sivas Basin, Central Anatolia. An integrated foraminiferal zonation provides new age assignments in terms of a great number of taxa for the studied sections. Four biostratigraphical intervals are first recorded based on the concurrent ranges of sporadically occurring but well preserved planktonic foraminiferal assemblages. The first interval characterized by the co-occurrences of Acarinina bullbrooki, Truncorotaloides topilensis and Turborotalia cerroazulensis is referable to the E11 Zone of late Lutetian-early Bartonian. An assemblage yielding Paragloborotalia opima accompanied by Globigerinella obesa forms a basis for the late Chattian O5 Zone. The successive interval corresponds to the late Chattian O6 Zone indicated by the presence of Globigerina ciperoensis and Globigerinoides primordius along with the absence of Paragloborotalia opima. The early Aquitanian M1 Zone can be tentatively defined based mainly on the assemblage of Globigerina, Globigerinella, Globoturborotalita and Tenuitella. The biostratigraphical data obtained from the benthic foraminifera assign the studied sections to the SBZ 21-22, SBZ 23 and SBZ 24 ranging in age from Rupelian to Aquitanian. The SBZ 23 and 24 are well constrained biozones by the occurrences of Miogypsinella complanata and Miogypsina gunteri, respectively, whereas the SBZ 21-22 defined by nummulitids and lepidocylinids in the Tethyan Shallow Benthic Zonation is characterized dominantly by peneroplids, soritids and miliolids in the studied sections. Benthic foraminiferal assemblages suggest different paleoenvironments covering lagoon, algal reef and shallow open marine whereas planktonic foraminifera provides evidence for relatively deep marine settings on the basis of assemblages characterized by a mixture of small-sized simple and more complex morphogroups indicative for intermediate depths of the water column.

  14. Effects of CO2 Hydrate on Deep-Sea Foraminiferal Assemblages

    Energy Technology Data Exchange (ETDEWEB)

    Ricketts, E R; Kennett, J P; Hill, T M; Barry, J P

    2005-06-01

    THE EFFECTS OF CO2 HYDRATE ON DEEP-SEA FORAMINIFERAL ASSEMBLAGES E. R. Ricketts*, J. P. Kennett and T. M. Hill Department of Geological Sciences University of California, Santa Barbara, CA USA Jim Barry Monterey Bay Aquarium Research Institute Moss Landing, CA USA ABSTRACT This study, conducted with the Monterey Bay Aquarium Research Institute (MBARI), is the first to investigate potential effects of CO2 hydrates on benthic microfossils, specifically foraminifera. The experiment was conducted in September 2003 aboard the R/V Western Flier using the ROV Tiburon. Experimental (CO2 exposed) and control cores were collected at 3600m and stained to distinguish live (stained) from dead (unstained) individuals. Foraminifera are ideal because of differing test composition (calcareous and agglutinated) and thickness, and diverse epifaunal and infaunal depth preferences. The effects of the CO2 on assemblages have been tracked both vertically (10cm depth) and horizontally, and between live and dead individuals. Increased mortality and dissolution of calcareous forms resulted from exposure to CO2 hydrate. Preliminary results suggest several major effects on surface sediment assemblages: 1) total number of foraminifera in a sample decreases; 2) foraminiferal diversity decreases in both stained and unstained specimens. The number of planktonic and hyaline calcareous tests declines greatly, with milliolids being more resistant to dissolution when stained; and 3) percentage of stained (live) forms is higher. Down-core trends (up to 10cm) indicate: 1) percent agglutinated forms decline and calcareous forms increasingly dominate; 2) agglutinated diversity decreases with depth; and 3) assemblages become increasingly similar with depth to those in control cores not subjected to CO2 hydrate. These results imply almost complete initial mortality and dissolution upon CO2 hydrate emplacement.

  15. The northern coast of the Ottnangian (middle Burdigalian, early Miocene) Molasse Sea in Germany: sediments, foraminiferal assemblages and biostratigraphy

    Science.gov (United States)

    Pippèrr, Martina; Reichenbacher, Bettina; Doppler, Gerhard; Hagmaier, Mischa; Jung, Dietmar

    2016-04-01

    This study provides new data on the litho- and biostratigraphy of the middle Burdigalian (Ottnangian) marine sediments at or close to the former northern coastline of the German Molasse Basin, based on cores from three boreholes (Burgau, Hamlar 2 and Lutzingen) and two outcrops (Haunsheim and Dattenhausen). Methods include quantitative analysis of benthic foraminiferal assemblages (90 samples), studies of planktonic foraminifers and ostracods and investigations of lithofacies. The data indicate that the transgressive-regressive marine sediments of the Upper Marine Molasse (OMM) at Burgau and Hamlar 2 can be subdivided into the well-known lower and middle Ottnangian sedimentation cycles, with the first cycle being represented by the "OMM-Basisschichten" and Kalkofen Formation and the second by the Baltringen and Steinhöfe Formations. We show for the first time that also the northernmost marginal-marine OMM facies (Lutzingen, Haunsheim and Dattenhausen) can be correlated with the lower and middle Ottnangian sedimentation cycles. Consequently, our results do not support the presence of a previously suggested third sedimentation cycle within the OMM sediments. Our micropaleontological data reveal regionally diverse depositional environments, reflecting different water depths and co-varying environmental variables. Significant differences in abundance, diversity and species composition of the benthic foraminiferal assemblages demonstrate marginal-marine facies for Lutzingen, Haunsheim and Dattenhausen, nearshore facies for Hamlar 2 and shallow marine basin facies for Burgau. The characteristic lower Ottnangian benthic foraminiferal species exhibit restricted ecological tolerances. Hence, the absence or scarcity of these species in nearshore to marginal-marine deposits has no stratigraphic significance. The presence of two sedimentation cycles in the western German Molasse Basin alone may have resulted from the interplay of regional tectonics and basin development that

  16. Assessing the suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Manasa, M.; Saraswat, R.; Nigam, R.

    inorganic carbon analysis is ±0.95%. Total carbon (TC) was measured with a CE NCS 2500 elemental analyzer. Suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from BoB 575 In order to identify the relationship between various... benthic foraminifera (AABF), (d) rounded symmetrical benthic foraminifera (RSBF), (e) agglutinated foraminifera, (f) Nonions, (g) Asterorotalids, (h) organic carbon (Corg), and (i) total inorganic carbon (TIC) in the continental shelf region...

  17. Assessing the suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from Bay of Bengal

    Indian Academy of Sciences (India)

    M Manasa; Rajeev Saraswat; Rajiv Nigam

    2016-04-01

    Temporal changes in benthic foraminiferal morpho-groups were suggested as an effective proxy to reconstructpast monsoon intensity from the Arabian Sea. Here, in order to test the applicability of temporalvariation in morpho-groups to reconstruct past monsoon intensity from the Bay of Bengal, we havedocumented recent benthic foraminiferal distribution from the continental shelf region of the northwesternBay of Bengal. Based on the external morphology, benthic foraminifera were categorized intorounded symmetrical (RSBF) and angular asymmetrical benthic foraminifera (AABF). Additionally, afew other dominant groups were also identified based on test composition (agglutinated, calcareous) andabundance (Asterorotalids and Nonions). The relative abundance of each group was compared with theambient physico-chemical conditions, including dissolved oxygen, organic matter, salinity and temperature.We report that the RSBF are abundant in comparatively warm and well oxygenated waters of lowsalinity, suggesting a preference for high energy environment, whereas AABF dominate relatively cold,hypersaline deeper waters with low dissolved oxygen, indicating a low energy environment. The agglutinatedforaminifera, Asterorotalids and Nonions dominate shallow water, low salinity regions, whereasthe calcareous benthic foraminiferal abundance increases away from the riverine influx regions. Foodavailability, as estimated from organic carbon abundance in sediments, has comparatively less influenceon faunal distribution in the northwestern Bay of Bengal, as compared to dissolved oxygen, temperatureand salinity. We conclude that the factors associated with freshwater influx affect the distributionof benthic foraminiferal morpho-groups in the northwestern Bay of Bengal and thus it can be used toreconstruct past monsoon intensity from the Bay of Bengal.

  18. Benthic foraminiferal response to heavy metal pollution in Izmir Bay (eastern Aegean Sea)

    International Nuclear Information System (INIS)

    Benthic foraminifera are interestingly used as environmental bio-indicators, especially in polluted environments where their sensitivity to pollutants may be expressed by a modification of the assemblages. Sixteen sediment samples were collected in November 2002 from surficial sediments of Izmir Bay for the study of foraminiferal assemblages. Izmir Bay is located in Western Turkey and surrounded by a densely populated community. Foraminifera (class Foraminifera, phylum Granuloreticulata) are among the more abundant protozoa in marine and brackish water habitats. They are unicellular protista that construct shells of one and many chambers. Studies of pollution effects on benthic foraminifera were initiated by Resig (1960) and Watkins (1961). The studies have often focused on areas exposed to direct pollution sources such as industrial, agricultural wastes. Some studies also take into account thermal and various kinds of chemical pollution and heavy metal pollution. In our research, we identified 28 foraminifera species. A total of 16 sediment samples used for this study come from selected stations at Izmir Bay. Heavy metals and chemicals are unlikely to favor any particular species of benthic foraminifera. In practice, however, it is often difficult to separate effects caused by heavy metals from those caused by organic material because most polluted areas are subjected to some kind of organic enrichments. Of the major environmental components (water, sediment, flora and fauna), sediments have been thoroughly analyzed to study the occurrence and distribution of metals. They present the clearest indication of metal input and accumulation in aquatic environments. Izmir Bay has been contaminated by numerous heavy metals, but geochemical analyses have shown that metals are significant pollutants in the inner part of the bay. Correlation analysis shows that there is a significant correlation between foraminifera species and heavy metals. Amphycoryna scalaris has

  19. Assessing the suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from Bay of Bengal

    Science.gov (United States)

    Manasa, M.; Saraswat, Rajeev; Nigam, Rajiv

    2016-04-01

    Temporal changes in benthic foraminiferal morpho-groups were suggested as an effective proxy to reconstruct past monsoon intensity from the Arabian Sea. Here, in order to test the applicability of temporal variation in morpho-groups to reconstruct past monsoon intensity from the Bay of Bengal, we have documented recent benthic foraminiferal distribution from the continental shelf region of the northwestern Bay of Bengal. Based on the external morphology, benthic foraminifera were categorized into rounded symmetrical (RSBF) and angular asymmetrical benthic foraminifera (AABF). Additionally, a few other dominant groups were also identified based on test composition (agglutinated, calcareous) and abundance (Asterorotalids and Nonions). The relative abundance of each group was compared with the ambient physico-chemical conditions, including dissolved oxygen, organic matter, salinity and temperature. We report that the RSBF are abundant in comparatively warm and well oxygenated waters of low salinity, suggesting a preference for high energy environment, whereas AABF dominate relatively cold, hypersaline deeper waters with low dissolved oxygen, indicating a low energy environment. The agglutinated foraminifera, Asterorotalids and Nonions dominate shallow water, low salinity regions, whereas the calcareous benthic foraminiferal abundance increases away from the riverine influx regions. Food availability, as estimated from organic carbon abundance in sediments, has comparatively less influence on faunal distribution in the northwestern Bay of Bengal, as compared to dissolved oxygen, temperature and salinity. We conclude that the factors associated with freshwater influx affect the distribution of benthic foraminiferal morpho-groups in the northwestern Bay of Bengal and thus it can be used to reconstruct past monsoon intensity from the Bay of Bengal.

  20. Benthic foraminiferal response to heavy metal pollution in Izmir Bay (Eastern Aegean Sea)

    International Nuclear Information System (INIS)

    Benthic foraminifera are increasingly used as environmental bio-indicators especially in polluted environments where their sensitivity to pollutants may be expressed by a modification of their test structure and by the change of the assemblages. The Gulf of Izmir is located in western Turkey and surrounded by a densely populated community. It has been contaminated by numerous heavy metals, geochemical analyses have shown that metals are significant pollutants in the inner part of the bay. Outer and middle sections showed low levels of heavy metal enrichments except for the estuary of the Gediz River. Foraminifera (class Foraminifera, phylum Granuloreticulata) are among the more abundant protozoa in marine and brackish water habitats. They are unicellular protista that construct shells of one and many chambers. Their sizes range from 100 microns to 20 cm. Studies of pollution effects on benthic foraminifera were initiated by Resig and Watkins. The effects of heavy metals pollution on foraminifera are studied. Sediment samples were collected from 16 stations in the Gulf of Izmir during the R/V K.Piri Reis cruise in November 2002 in the framework of the Gulf of Izmir Marine Research Project. Sediment samples were taken using Van-Veen Grab sampler that collects sediment over a surface of about 400 cm2. A constant volume of 50 cm3 of sediment was taken from the upper 1 cm of each sample. The samples for metal analyses were dried in a freeze dryer, homogenized and reduced to a fine powder. Samples were digested in a microwave digestion system (Milestone 1200) with a HNO3-HF-HClO4- HCl acid mixture solutions and were analyzed by flame and graphite furnace AAS (Varian Spectraa-300 plus). The foraminifera are identified according to the criteria laid down by [6] and [7]. A total of 16 sediment samples were used for this study from the Gulf of Izmir. For foraminiferal research 20 grams of dry sediment were treated with 17% H2O2 and left for 24 hours within it. The samples

  1. Foraminiferal assemblages as palaeoenvironmental bioindicators in Late Jurassic epicontinental platforms: relation with trophic conditions

    OpenAIRE

    Reolid, Mat??as; Nagy, Jen??; Rodr??guez-Tovar, Francisco J.; Ol??riz S??ez, Federico

    2008-01-01

    Foraminiferal assemblages from the neritic environment reveal the palaeoecological impact of nutrient types in relation to shore distance and sedimentary setting. Comparatively proximal siliciclastic settings from the Boreal Domain (Brora section, Eastern Scotland) were dominated by inner???shelf primary production in the water column or in sea bottom, while in relatively seawards mixed carbonate???siliciclastic settings from the Western Tethys (Prebetic, Southern Spain), nutrients mainly der...

  2. Laboratory experiment to study the effect of salinity variations on benthic foraminiferal species - Pararotalia nipponica (Asano)

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Saraswat, R.; Kurtarkar, S.R.

    -1 JOURNAL GEOLOGICAL SOCIETY OF INDIA Vol.67, January 2006, pp.41-46 Laboratory Experiment to Study the Effect of Salinity Variations on Benthic Foraminiferal Species - Pararotalia nipponica (Asano) RAJIV NIGAM, RAJEEV SARASWAT* and SUJATA R. KURTARKAR... variations. Various workers have investigated the effects of salinity on growth and overall size of foraminifers (see Boltovskoy et al. 1991, for review). Even though a vast amount of literature, based on field observations, is available on the effect...

  3. Marine historical ecology at the Brijuni Islands, Croatia: preliminary results from down-core changes of foraminiferal assemblages

    Science.gov (United States)

    Vidovic, Jelena; Cosovic, Vlasta; Gallmetzer, Ivo; Haselmair, Alexandra; Zuschin, Martin

    2015-04-01

    The Late Holocene in the northern Adriatic is characterized by the eustatic peak of the sea-level rise, followed by the equilibrium between the regional tectonic subsidence and hydro-isostatic emergence and relatively stable sea level for a few thousand years. During this period the area experienced changes in sedimentation rate, food/oxygen availability in the benthic ecosystem and eutrophication with seasonal hypoxic and anoxic events. In order to reconstruct the marine paleoecology in the Brijuni Islands area during this period, a multidisciplinary study was carried out, including geochemical (TOC, trace metals, carbonate content), micropaleontological analyses (benthic foraminifera) and dating of sediments and mollusc shells. The principal aim of this study is to observe the effects of ecological shifts on foraminiferal assemblages during the Late Holocene. One core of 1.5 m length was taken at a sampling station south of Veli Brijuni Island, located within a marine protected area with no fishing/dredging pressure (Croatian national park). The core was sliced into smaller subsamples, and four sediment fractions of each subsample (63, 125, 250 and 500 µm) were analyzed for standard properties of the foraminiferal community (species richness, faunal composition, biodiversity indices), in comparison with relevant physical and geochemical properties of the sediment. The results concerning changes in foraminiferal species composition and abundance point to differences within the core: surface sediments are dominated by suspension feeders (Planorbulina mediterranensis, Lobatula lobatula, Cibicides variabilis, Cibicides refulgens), whereas deposit feeders (genera Textularia, Siphonaperta, Adelosina, Trioculina) appear in higher abundances at approximately 30 cm of the sediment depth and dominate down-core. Species richness in the first 30 cm is lower (10 to 34 species per sample) in comparison to the middle part of the core (39 to 53 species), and decreases again at

  4. Minimal influence of recrystallization on middle Miocene benthic foraminiferal stable isotope stratigraphy in the eastern equatorial Pacific

    Science.gov (United States)

    Voigt, Janett; Hathorne, Ed C.; Frank, Martin; Holbourn, Ann

    2016-01-01

    Stable carbon and oxygen isotopes (δ13C and δ18O) of foraminiferal tests are amongst the most important tools in paleoceanography, but the extent to which recrystallization can alter the isotopic composition of the tests is not well known. Here we compare three middle Miocene (16-13 Ma) benthic foraminiferal stable isotope records from eastern equatorial Pacific sites with different diagenetic histories to investigate the effect of recrystallization. To test an extreme case, we analyzed stable isotope compositions of benthic foraminifera from Integrated Ocean Drilling Program Site U1336, for which the geochemistry of bulk carbonates and associated pore waters indicates continued diagenetic alteration in sediments > 14.7 Ma. Despite this diagenetic overprinting, the amplitudes and absolute values of the analyzed U1336 stable isotopes agree well with high-resolution records from better preserved Sites U1337 and U1338 nearby. Our results suggest that although benthic foraminiferal tests of all three sites show some degree of textural changes due to recrystallization, they have retained their original stable isotope signatures. The good agreement of the benthic foraminiferal stable isotope records demonstrates that recrystallization occurred extremely rapidly (waters during late recrystallization. The close similarity of the benthic foraminiferal stable isotope records between the sites allows the well-resolved paleomagnetic results of Site U1336 to be transferred to Sites U1337 and U1338 improving the global geological timescale.

  5. Cold seeps in Monterey Bay, California: Geochemistry of pore waters and relationship to benthic foraminiferal calcite

    Energy Technology Data Exchange (ETDEWEB)

    Gieskes, Joris, E-mail: jgieskes@ucsd.edu [Scripps Institution of Oceanography, IOD-0208, 9500 Gilman Drive, La Jolla, CA 92093-0208 (United States); Rathburn, Anthony E. [Scripps Institution of Oceanography, IOD-0208, 9500 Gilman Drive, La Jolla, CA 92093-0208 (United States)] [Indiana State University, Department of Earth and Environmental Systems, Terre Haute, IN 47809 (United States); Martin, Jonathan B. [University of Florida, Department of Geological Sciences, Gainesville, FL 32611-2120 (United States); Perez, M. Elena [Indiana State University, Department of Earth and Environmental Systems, Terre Haute, IN 47809 (United States)] [The Natural History Museum, Department of Palaeontology, Cromwell Road, London SW7 5BD (United Kingdom); Mahn, Chris [Scripps Institution of Oceanography, IOD-0208, 9500 Gilman Drive, La Jolla, CA 92093-0208 (United States); Bernhard, Joan M. [Woods Hole Oceanographic Institution, Geology and Geophysics Department, MS52, Woods Hole, MA 02543 (United States); Day, Shelley [University of Florida, Department of Geological Sciences, Gainesville, FL 32611-2120 (United States)

    2011-05-15

    Highlights: > We describe the geochemistry of pore waters in the Clam Flats area of Monterey Bay. > The geochemical data are compared with the {delta}{sup 13}C chemistry of benthic foraminifera. > Living foraminifera indicate little effects of pore water low {delta}{sup 13}C (DIC) in the clam bed. > This phenomenon and its implications are discussed in detail. > Implications with regards to paleo-methane seepage are discussed. - Abstract: An extensive geochemical and biogeochemical examination of CH{sub 4} seeps in the Clam Flats area of Monterey Bay provides insight into the character of relationships between seep geochemistry and benthic foraminiferal geochemistry. The area is characterized by sulfide-rich fluids. Sulfide increases are associated with large increases in alkalinity, as well as small decreases in dissolved Ca and Mg. In addition, only small increases in NH{sub 4} are observed, but values of {delta}{sup 13}C of dissolved inorganic C are as low as -60 per mille at shallow depths (<3 cm). These observations indicate that all these processes are related to the bacterial oxidation of CH{sub 4}, which is transported upward by slow seepage of pore fluids. The geochemistry of the pore fluids should be relevant to the geochemistry of the carbonate tests of living and dead foraminifera. However, a profound disequilibrium of approximately an order of magnitude occurs between the {delta}{sup 13}C values of stained (cytoplasm-containing) foraminiferal carbonate and the C isotope values of ambient pore water dissolved inorganic C. Reasons are unclear for this isotopic disequilibrium, but have important implications for interpretations of foraminiferal carbonate as a paleoenvironmental proxy. Much fine scale work is needed to fully understand the relationships between the biogeochemistry of benthic foraminifera and the geochemistry of the pore waters where they live.

  6. Benthic foraminiferal census data from Mobile Bay, Alabama--counts of surface samples and box cores

    Science.gov (United States)

    Richwine, Kathryn A.; Osterman, Lisa E.

    2012-01-01

    A study was undertaken in order to understand recent environmental change in Mobile Bay, Alabama. For this study a series of surface sediment and box core samples was collected. The surface benthic foraminiferal data provide the modern baseline conditions of the bay and can be used as a reference for changing paleoenvironmental parameters recorded in the box cores. The 14 sampling locations were chosen in the bay to cover the wide diversity of fluvial and marine-influenced environments on both sides of the shipping channel.

  7. Stable isotope and benthic foraminiferal records of the Latest Danian Event at ODP Site 1262 (Walvis Ridge)

    Science.gov (United States)

    Deprez, Arne; Jehle, Sofie; Bornemann, André; Speijer, Robert P.

    2015-04-01

    The Latest Danian Event (LDE - aka Top Chron 27n Event) is characterized by a >1o negative benthic foraminiferal CIE in various sections in Egypt, which has been correlated with δ13C shifts of ~0.7o in Zumaia (Spain), Wombat Plateau (ODP 761B, Indian Ocean) and Shatsky Rise (ODP 1209, Pacific Ocean) (Bornemann et al., 2009; Westerhold et al., 2011). A concurrent ~0.5o δ18O excursion suggests a 2°C bottom water temperature rise during this event at Shatsky Rise, suggesting a hyperthermal nature for this event (Westerhold et al., 2011). Here we show the first results of benthic foraminiferal faunal and isotope patterns related to the LDE at Walvis Ridge (ODP Site 1262, Southern Atlantic Ocean, paleodepth ~3000 m). The high percentage of planktic foraminifera (on average 99.2%) indicates good carbonate preservation. Stable isotope analyses on the benthic foraminifer Nuttallides truempyi show a ~0.9o δ13C shift at ~62.2 Ma. Lowest values are measured at ~62.15 Ma. A concurrent ~0.8o δ18O excursion indicates a ~3°C temperature rise, larger than at Shatsky Rise. δ13C values recover to reach a transient plateau at 0.75o during the second Fe peak (from ~62.1 to 62.0 Ma), coinciding with a second negative δ18O excursion of 0.7o. Also the ODP Site 1209 (Shatsky Rise) record shows these double Fe, δ18O and δ13C peaks. This is a feature that the LDE shares with some early Eocene hyperthermals, like ETM-2/H1-H2 and I1-I2, and might point to a common origin as the early Eocene hyperthermals. The Walvis Ridge samples show a highly diverse assemblage of benthic foraminifera with a relative abundance of 10-15% of Gyroidinoides spp. and ~10% of Nuttallides spp., Siphogenerinoides spp., Gavelinella spp., Epistominella spp. and Cibicidoides spp. The ~15cm sample interval dataset seems to show no large changes in relative abundance of these species at the onset of the LDE. This is different than faunal response to early Eocene hyperthermals, like ETM2. During ETM2 at DSDP

  8. Benthic foraminiferal thanatocoenoses from the Cap-Ferret Canyon area (NE Atlantic): A complex interplay between hydro-sedimentary and biological processes

    Science.gov (United States)

    Duros, P.; Jorissen, F. J.; Cesbron, F.; Zaragosi, S.; Schmidt, S.; Metzger, E.; Fontanier, C.

    2014-06-01

    Benthic foraminiferal thanatocoenoses from the Cap-Ferret Canyon area were studied in the >150-μm fraction of 4-5 cm deep sediment levels, at 13 stations. The shallowest station (151 m depth) is located at the shelf break, close to the canyon head. All other stations are located along two bathymetric transects: seven stations along the canyon axis between 300 and 3000 m depth, and five stations from 300 m to 2000 m depth along the southern flank of the canyon. The comparison between the live (Rose-Bengal-stained) and dead assemblages shows that biological (i.e. population dynamic) and taphonomic processes (i.e. test destruction, transport) generate important discrepancies between live and dead assemblages. An important question is, to what degree post-mortem transport and redeposition of foraminiferal tests contribute to the difference between living and dead assemblages? The composition of the thanatocoenoses (shells >150 μm from the inner continental shelf to the Cap-Ferret Canyon axis. However, transport of tests from outer shelf or upper canyon axis towards deeper sites occurs, as indicated by an increase of diversity indices of the dead fauna along the canyon axis. Moreover, some species (e.g., Cassidulina carinata) are observed in the living fauna restricted to the shallow sites, but occur in important amounts in the dead fauna at deeper stations, suggesting that these taxa have been transported from upper canyon stations toward deeper sites. Since Cap-Ferret Canyon is inactive in terms of massive sediment transport (i.e. gravity events), downslope transport of foraminiferal tests probably takes place in nepheloid layers. Downslope transports of foraminiferal tests may create important biases for the utilisation of paleoceanographic proxies using the assemblage characteristics and/or the geochemical composition of selected species. However, the study of dead assemblages along a canyon axis can give important clues about the sedimentary dynamics, especially

  9. Benthic foraminiferal fauna turnover at 2.1 Ma in the northern South China Sea

    Institute of Scientific and Technical Information of China (English)

    HUANG BaoQi; JIAN ZhiMin; WANG PinXian

    2007-01-01

    Quantitative analysis of benthic foraminifera from ODP Site 1146 in the northern South China Sea (SCS)shows that abundance of Bulimina alazanensis, sometimes up to about 90%, decreased gradually since 3.2 Ma, especially at 2.1 Ma. Abundance of other benthic foraminiferal species, Globobulimina subglobosa and Cibicidoides wuellerstorfi, increased after 2.1 Ma. Comparison with changes in oxygen and carbon isotopes of planktonic and benthic foraminifera shows that high abundance values of B.alazanensis corresponded with lower values of oxygen isotope, but for carbon isotope, high values of the species were consistent with heavier carbon Isotope of benthic foraminifera and lighter carbon isotope of planktonic foraminifera, respectively, and vice versa. Considering factors such as uplift of Bashi Strait, expansion of the North Hemisphere Glaciation, strengthening of East Asian winter monsoon and variations in oxygen and carbon isotope of foraminifera, changes of B. alazanensis in ODP Site 1146 suggest that the source of deep water masses of the northern South China Sea changed from the warm Pacific deep water with high oxygen content to Pacific Intermediate water with Iow oxygen content at 2.1 Ma. In addition, the strengthened East Asian winter monsoon resulted in increased primary productivity, high nutrient and suboxic bottom water. Variations in species of B. alazanensis seemed to be unable to tolerate environmental stress induced by deep water masses and productivity changes.

  10. Centennial scale benthic foraminiferal record of late Holocene oceanographic variability in Disko Bugt, West Greenland

    Science.gov (United States)

    Perner, K.; Moros, M.; Lloyd, J. M.; Kuijpers, A.; Telford, R. J.; Harff, J.

    2011-09-01

    A new centennial scale benthic foraminiferal record of late Holocene climate variability and oceanographic changes off West Greenland (Disko Bugt) highlights substantial subsurface water mass changes (e.g. temperature and salinity) of the West Greenland Current (WGC) over the past 3.6 ka BP. Benthic foraminifera reveal a long-term late Holocene cooling trend, which may be attributed to increased advection of cold, low-salinity water masses derived from the East Greenland Current (EGC). Cooling becomes most pronounced from c. 1.7 ka BP onwards. At this point the calcareous Atlantic benthic foraminiferal fauna decrease significantly and is replaced by an agglutinated Arctic fauna. Superimposed on this cooling trend, centennial scale variability in the WGC reveals a marked cold phase at c. 2.5 ka BP, which may correspond to the 2.7 ka BP cooling-event recorded in marine and terrestrial archives elsewhere in the North Atlantic region. A warm phase recognized at c. 1.8 ka BP is likely to correspond to the 'Roman Warm Period' and represents the warmest bottom water conditions. During the time period of the 'Medieval Climate Anomaly' we observe only a slight warming of the WGC. A progressively more dominant cold water contribution from the EGC on the WGC is documented by the prominent rise in abundance of agglutinated Arctic water species from 0.9 ka BP onwards. This cooling event culminates at c. 0.3 ka BP and represents the coldest episode of the 'Little Ice Age'. Gradually increased influence of cold, low-salinity water masses derived from the EGC may be linked to enhanced advection of Polar and Arctic water by the EGC. These changes are possibly associated with a reported shift in the large-scale North Atlantic Oscillation atmospheric circulation pattern towards a more frequent negative North Atlantic Oscillation mode during the late Holocene.

  11. Calibration of the carbonate `clumped isotope' paleotemperature proxy using mollusc shells and benthic foraminiferal tests

    Science.gov (United States)

    Came, R. E.; Curry, W. B.; Weidman, C. R.; Eiler, J. M.

    2007-12-01

    It has recently been shown that the carbonate `clumped isotope' thermometer can provide temperature constraints that depend only on the isotopic composition of carbonate (in particular, on the proportion of 13C and 18O that form bonds with each other), and that do not require assumptions about the isotopic composition of the water in which the carbonate formed (Ghosh et al., 2006). Furthermore, this novel method permits the calculation of seawater δ18O based on the clumped isotope temperature estimates and the simultaneously obtained δ18O of carbonate, thereby enabling the extraction of global ice volume estimates for both the recent and distant geologic past. Here we present clumped isotope analyses of several naturally occurring marine carbonates that calcified at known temperatures in the modern ocean. First, we analyzed benthic foraminiferal tests from six high-quality multicore tops collected in the Florida Strait, spanning a temperature range of 9.3-20.2 degrees C. Second, we analyzed shallow-water mollusc shells from a variety of different climate regimes, spanning a temperature range of 2.5-26.0 degrees C. We find that the calcitic foraminiferal species Cibicidoides spp. agrees well with the inorganic calcite precipitation experiments of Ghosh et al. (2006), while the aragonitic species Hoeglundina elegans is significantly offset. Similarly, clumped isotope results obtained from aragonitic mollusc shells also reveal an offset from the Ghosh et al. (2006) trend, although the offset observed in mollusc aragonite is quite different in nature from that observed in foraminiferal aragonite. Assuming our estimates of the growth temperatures of these naturally occurring organisms are correct, these results suggest that there are vital effects associated with the stable isotope compositions of the aragonite-precipitating organisms examined in this study; further work will be required to determine their cause. Nevertheless, the internal coherence of trends for

  12. Uppermost Jurassic to Lower Cretaceous benthic foraminiferal biostratigraphy at ODP Site 765 on the Argo Abyssal Plain.

    OpenAIRE

    Kaminski, M.A.; Gradstein, F.M.; Geroch, S.

    1992-01-01

    Benthic foraminifers were studied in 99 samples collected from the lower 200 m of Hole 765C. The studied section ranges from the Tithonian to Aptian, and benthic foraminifers can be subdivided into five assemblages on the basis of faunal diversity and stratigraphic ranges of distinctive species. Compared with deep-water assemblages from Atlantic DSDP sites and Poland, assemblages from the Argo Abyssal Plain display a higher diversity of agglutinated forms, which comprise the autochthonous ...

  13. Ecological Factors Acting on the Microfauna in Mangrove Swamps. The Case of Foraminiferal Assemblages in French Guiana

    Science.gov (United States)

    Debenay, J.-P.; Guiral, D.; Parra, M.

    2002-10-01

    Thirty-seven surface sediment samples were collected in January 1999 and July 2000 in the mangrove swamps and mud flats of French Guiana where strong seasonal contrasts occur. Sampling stations were selected to provide information on the foraminiferal assemblages associated with different environmental conditions, on the mud banks and in the mangrove forest. A total of 44 species have been identified. The main parameter acting on the distribution of foraminiferal assemblages is the hydrodynamics of the estuary, characterized by the double influence of coastal water and low-Ca fresh water, with drastic seasonal changes. The coastal end member is dominated by the calcareous species Ammonia tepida, A. parkinsoniana and Cribroelphidium spp., the continental (freshwater) end member is characterized by Miliammina fusca and Trochamminita irregularis . The calcareous species penetrate into the estuary, even into the mangrove forest during the dry season, but totally disappear from the estuary during the rainy season. The second parameter acting on the distribution of foraminiferal assemblages is the vertical elevation that acts indirectly by influencing the time of aerial exposure and the colonization by mangrove trees. Both canopy and litter of the mangrove forest protect the sediment from heating, drying and increases in salinity due to sun and wind. Foraminifera are very rare or absent on the open mud banks affected by mud cracks, but begin to grow as soon as young Avicennia are present. In the mangrove swamps, local conditions influence the composition of the assemblages and the taphonomic processes.

  14. A culture-based calibration of benthic foraminiferal paleotemperature proxies: δ18O and Mg/Ca results

    Directory of Open Access Journals (Sweden)

    D. C. McCorkle

    2010-01-01

    Full Text Available Benthic foraminifera were cultured for five months at four temperatures (4, 7, 14 and 21 °C to establish the temperature dependence of foraminiferal δ18O and Mg/Ca. Two Bulimina species (B. aculeata and B. marginata were most successful, adding chambers at all four temperatures and reproducing at 7 and 14 °C. Foraminiferal δ18O values displayed ontogenetic variations, with lower values in younger individuals. The δ18O values of adult specimens decreased with increasing temperature in all but the 4 °C treatment, exhibiting a relationship consistent with previous δ18O paleotemperature calibration studies. Foraminiferal Mg/Ca values, determined by laser ablation inductively coupled plasma mass spectrometry, were broadly consistent with previous Mg/Ca calibration studies, but extremely high values in the 4 °C treatment and higher than expected values at two of the other three temperatures make it challenging to interpret these results.

  15. 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...

  16. Benthic foraminiferal micro-ecology and the geochemical environments they sample

    Science.gov (United States)

    Jacobsen, Brittani; Loubere, Paul; Yavorska, Iryna; Klitgaard-Kristensen, Dorthe; Jernas, Patrycja

    2010-05-01

    Benthic foraminifera inhabit, and are adapted to, microenvironments ranging from within the water column to centimeters into the sediments. These influence the geochemistry of the foraminiferal shell, and the paleoceanographic tracers we extract from that geochemistry. For a number of proxies it is important to know what geochemical environments the foraminifera are calcifying in, and whether species are consistent in the habitats they select for calcification. We examine these issues by sampling pore water chemistry and living species distributions on the microscale that the foraminifera themselves experience. We maintained cores from the Norwegian margin under in-situ conditions while measuring oxygen microprofiles and small scale sampling for foraminifera using rose Bengal and cell tracker green staining. In addition we sampled cores for porosity and pore water carbon isotopes using two extraction techniques so as to measure isotope profiles and degree of sediment irrigation via infaunal structures. The primary forcing variable we examined was changing labile organic carbon flux to the seabed. Under moderate to higher fluxes we found evidence for extensive bio-irrigation which influenced the composition of pore waters and microhabitats available to foraminifera. Macro-meiofaunal burrows and tubes produced a mosaic of pore water geochemical conditions rather than smooth gradients from the sediment-water interface. We found species adapted to particular conditions living at various subsurface depths, where their preferred conditions existed. We also found evidence that foraminiferal species responded to larger organism activities (feeding activities) and products (fecal deposits). It appears that taxa select for particular conditions rather than simply living at specific subsurface depths, recording whatever geochemistry happens to exist at that level.

  17. Factors determining the distribution of foraminiferal assemblages in Port Joinville Harbor (Ile d'Yeu, France): the influence of pollution

    OpenAIRE

    Debenay, Jean-Pierre; Tsakiridis, Erica; Soulard, René; Grossel, Hubert

    2001-01-01

    Port Joinville harbor is located on an island. Thus, it receives only a few freshwater inputs, contrary to most of the areas where the influence of pollution on foraminiferal assemblages has been studied. The pollution in the harbor mainly results from the boats, including cleaning, painting and outfall of oil and motor-fuel.A total of 59 sediment samples was collected at three sampling periods (November-December 1997, May 1998 and September 1998). These samplings were supplemented by the stu...

  18. Implication of salt marsh foraminiferal assemblages in Suncheon Bay, South Korea

    Science.gov (United States)

    Jeong, Da Un; Lee, Yeon Gyu; Kang, Sora; Kim, Shin; Lee, Jung Sick

    2016-03-01

    Analyses of the compositions of benthic foraminifera and sediment, observations of tidal level and salinity, and a geographic survey of the tidal salt marsh in Suncheon Bay were conducted to examine the vertical distribution of foraminifera and evaluate their potential use for sea level studies. The salt marsh is composed mainly of fine-grained silty clay sediment and its salinity is below approximately 11 psu. The tidal current flows in the southwest-tonortheast direction with an average velocity of 26.57 cm/s. A total of 33 species of foraminifera (17 agglutinated and 16 calcareoushyaline) belonging to 24 genera was identified. The species diversity (1.1 on average) was relatively low. Dominant species were Ammonia beccarii, Miliammina fusca, Haplophragmoides wilberti, and Jadammina macrescens. Calcareous foraminifera (29.5%) were dominantly represented by the Ammonia beccarii assemblage, which characterized the region between mean tide level and mean low high water (MLHW). Agglutinated species (70.5%) were represented mostly by Miliammina fusca, Miliammina fusca-Haplophragmoides wilberti, and Haplophragmoides wilberti assemblages, which characterized the MLHW-mean high water (MHW), MHW-mean highest high water (MHHW), and MHHW-Approx. highest high water tide levels, respectively. In particular, the Haplophragmoides wilberti assemblage is believed to represent the highest elevation zone of foraminifera in the salt marshes of Suncheon Bay and is considered to be a reliable indicator of sea level as a result of its narrow vertical range.

  19. Cenomanian-Coniacian Upper Cretaceous foraminiferal fauna of Lithuania

    Science.gov (United States)

    Aleksienė, Agnė

    2010-12-01

    Foraminiferal assemblages form a unique fauna succession from the Cenomanian to Maastrichtian stages in Lithuania; the Cenomanian-Coniacian succession is discussed in this paper. The first Cretaceous planktonic foraminifera species appeared in the Early Cenomanian. The Cenomanian planktonic foraminiferal association consists of the relatively abundant genus Hedbergella. However, Cenomanian planktonic foraminifera are rare compared to benthic; the latter are numerous, and their assemblage contains various calcareous and agglutinated species. As a result of environmental changes, foraminiferal assemblages gradually changed as well. The newly formed deep-water niches in the Turonian allowed spreading the keeled forms of planktonic foraminifera. Taxonomically, Turonian-Coniacian foraminiferal assemblages are mainly composed of species of the following genera: Praeglobotruncana, Helvetoglobotruncana, Dicarinella, Marginotruncana.

  20. A survey of benthic assemblages of foraminifera in tropical coastal waters of pulau pinang, malaysia.

    Science.gov (United States)

    Minhat, Fatin Izzati; Yahya, Khairun; Talib, Anita; Ahmad, Omar

    2013-08-01

    The distribution of benthic Foraminifera throughout the coastal waters of Taman Negara Pulau Pinang (Penang National Park), Malaysia was studied to assess the impact of various anthropogenic activities, such as fishing, ecotourism and floating cage culture. Samples were obtained at 200 m intervals within the subtidal zone, extending up to 1200 m offshore at Teluk Bahang, Teluk Aling, Teluk Ketapang and Pantai Acheh. The depth within coastal waters ranged between 1.5 m and 10.0 m, with predominantly muddy substrate at most stations. Water quality analysis showed little variation in micronutrient (nitrite, NO2; nitrate, NO3; ammonia, NH4 and orthophosphate, PO4) concentrations between sampling stations. Temperature (29.6±0.48°C), salinity (29.4±0.28 ppt), dissolved oxygen content (5.4±0.95 mg/l) and pH (8.5± 0.13) also showed little fluctuation between stations. A total of nine genera of foraminifera were identified in the study (i.e., Ammonia, Elphidium, Ammobaculites, Bigenerina, Quinqueloculina, Reopax, Globigerina, Textularia and Nonion). The distribution of benthic foraminifera was dominated by opportunistic groups that have a high tolerance to anthropogenic stressors. Ammonia had the highest frequency of occurrence (84.7%), followed by Bigenerina (50%), Ammobaculites (44.2%) and Elphidium (38.9%). The Ammonia-Elphidium Index (AEI) was used to describe the hypoxic condition of benthic communities at all sites. Teluk Bahang had the highest AEI value. The foraminiferal assemblages and distribution in Teluk Bahang, Teluk Aling, Teluk Ketapang and Pantai Acheh showed no correlation with physical or chemical environmental parameters. PMID:24575240

  1. 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...

  2. The San Miguel de Salinas section (Bajo Segura Basin). Palaeoenvironmental significance of the foraminiferal assemblages related to the Messinian Salinity Crisis

    OpenAIRE

    Corbí, Hugo; Caracuel, Jesús Esteban; Dinarès Turell, Jaume; Lancis, Carlos; Pina, José Antonio; Soria, Jesús M.; Tent Manclús, José Enrique; Yébenes, Alfonso

    2009-01-01

    In the composite section of San Miguel de Salinas the following synthems are represented: MI (preevaporitic Messinan), MII (syn-evaporitic Messinian) and P (post-evaporitic Pliocene). The foraminiferal assemblages of these synthems have been studied in order to reveal the palaeoenvironmental changes related to the Mediterranean Salinity Crisis. The change between MI and MII synthems is characterized by the reduction of the foraminiferal biodiversity. Synthem MII records palaeoenvironmental st...

  3. FACIES CONTROL ON THE COMPOSITION OF SERPUKHOVIAN AND EARLY BASHKIRIAN FORAMINIFERAL ASSEMBLAGES IN THE MIDDLETIEN-SHAN MOUNTAINS, CENTRAL ASIA

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    OLGA ORLOV-LABKOVSKY

    2003-07-01

    Full Text Available Serpukhovian-lower Bashkirian deposits are widely developed in the Middle Tien-Shan Mountains of Uzbekistan and adjacent countries of Central Asia. These deposits formed in a sedimentary basin exhibiting four distinctive facies that differ in foraminiferal diversity and population density. The facies types, named for mountain ranges containing representative sections, are called 1 Talassic, for inner shelf, shallow- water marine carbonates; 2 Ugamic, for carbonaceous deposits accumulating on an open, shallow-water, outer carbonate shelf platform; 3 Karzhantauic, for interbedded volcaniclastics and shallow-water marine carbonates deposited on a eroded surface; and  4 Paltauic, for basinal beds containing thin-bedded, graded and laminated organic limestones and interbedded turbidites. A statistical program (Sorenson's Coefficients of Species Similarity was used to compare assemblages in eight foraminiferal zones from coeval fades across the basin. Highest similarity coefficients occur in the early Serpukhovian and are probably related to a marine transgression that flooded the basin. Regression and volcaniclastic sedimentation account for lower coefficients in the remainder of the Serpukhovian. Increased foraminiferal diversity and abundance in the earliest Bashkirian were probably caused by the opening of new connections to adjacent Paleotethyan basins only to be followed by more restricted environmental conditions and lower similarity coefficients later in the early Bashkirian. 

  4. Non-lethal effects of ocean acidification on two symbiont-bearing benthic foraminiferal species

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    A. McIntyre-Wressnig

    2011-09-01

    Full Text Available We conducted experiments to assess the effect of elevated atmospheric carbon dioxide concentrations on survival, fitness, shell microfabric and growth of two species of symbiont-bearing coral-reef benthic foraminifera, using pCO2 Ievels similar to those likely to occur in shallow marine pore waters in the decades ahead. Foraminifera were cultured at constant temperature and controlled pCO2 (385 ppmv, 1000 ppmv, and 2000 ppmv for six weeks, and total alkalinity and dissolved inorganic carbon were measured to characterize the carbonate chemistry of the incubations. Foraminiferal survival and cellular energy levels were assessed using Adenosine Triphosphate (ATP analyses, and test microstructure and growth were evaluated using high resolution SEM and image analysis. Fitness and survival of Amphistegina (A. gibbosa and Archaias (A. angulatus were not directly affected by elevated pCO2 and the concomitant decrease in pH and calcite saturation states (Ωc values of the seawater (pH and Ωc values of 8.12, 7.86, and 7.50, and 5.4, 3.4, and 1.5, for control, 1000 ppmv, and 2000 ppmv, respectively. In A. gibbosa, a species precipitating low-Mg calcite, test growth was not affected by elevated pCO2, but areas of dissolved calcium carbonate were observed even though Ωc was >1 in all treatments; the fraction of test area dissolved increased with decreasing Ωc. Similar dissolution was observed in offspring produced in the 2000 ppmv pCO2 treatments. In A. angulatus, whose tests are more-solubile high-Mg calcite, growth was greatly diminished in the 2000 ppmv pCO2 treatment compared to the control. These non-lethal effects of ocean acidification – reduced growth in A. angulatus, and enhanced dissolution in A. gibbosa – may reflect differences in test mineralogy

  5. Culturing Fundamentals Used To Design And Execute A Long-Term Multi-stressor Experiment To Assess Impact Of Deoxygenation, Ocean Acidification, And Warming On Benthic Foraminiferal Community Composition, Growth, And Carbonate Yield: Design And Results

    Science.gov (United States)

    Bernhard, J. M.; Wit, J. C.

    2015-12-01

    The geochemistry recorded in carbonate foraminiferal tests (shells) is often used as proxy for past oceanographic events and environments. By understanding past oceanic and climatic conditions, we can better predict future climate scenarios, a relevant ability in these times of global change. The fact that foraminifera are biological entities can be pivotal for understanding their geochemical records. Thus, growing foraminifera under known physicochemical conditions and analyzing the geochemistry of their cultured carbonate can yield insightful perspectives for proxy refinement and development. Because parameters often co-vary in nature, proper proxy calibration can only be done with materials grown in strictly controlled and known environments. This presentation will review the various crucial aspects of foraminiferal maintenance and culturing, especially from the perspective of proxy development. These fundamentals were used to design a long-term multi-stressor experiment with oxygen, pCO2 (pH), and temperature as variables to test the single, double or triple threats of deoxygenation, ocean acidification, and oceanic warming. Results on assemblage composition, survivorship and growth of a continental shelf benthic foraminiferal community will be presented. Although one agglutinated morphospecies grew in each of the five treatments, growth of individual calcareous species was more restricted. Initial results indicate that pCO2 was not the factor that impacted communities most. Supported in part by NSF OCE-1219948.

  6. Palaeoceanographic implications of abundance and mean proloculus diameter of benthic foraminiferal species Epistominella exigua in sub-surface sediments from distal Bay of Bengal fan

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.; Nigam, R.; Barreto, L.

    surface (Murray 1991). E. exigua is a sporadically epifaunal detri- tivore, usually associated with a pulsed supply of phytodetritus and elevated oxygen concentrations (Gooday 1993; Mackensen et al 1995; Schmiedl et al 1997; Nees and Struck 1999; Gupta...?358. Murray J W 1991 Ecology and Paleoecology of Benthic Foraminifera. John Wiley, New York and Longman Sci- entific and Technical, Harlow, UK 1?397. Nees S and Struck U 1999 Benthic foraminiferal response to major paloeceanographic changes. In: Reconstructing...

  7. Benthic foraminifera as bioindicators of anthropogenic impacts in two north African lagoons: a comparison with ostracod assemblages

    OpenAIRE

    Ruiz Muñoz, Francisco; González-Regalado Montero, María Luz; Galán Huertos, Emilio; González, María Isabel; Prudencio, María Isabel; Dias, María Isabel; Abad de los Santos, Manuel; Toscano Grande, Antonio; Prenda Marín, José; García García, Edith Xiomara

    2012-01-01

    Numerous investigations have used the foraminiferal assemblages or species as bioindicators. This paper tests the responses of these microorganisms to different environmental changes (heavy metal pollution, treatment stations, artificial inlets, agricultural and urban sewages) and compares them to those observed previously on ostracod assemblages. Foraminifera are more tolerant to these changes, while ostracods present a more specialized response. Numerosas investigaciones han ...

  8. 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.

  9. The benthic foraminiferal response to late Holocene climate change over northern Europe

    OpenAIRE

    Hass, H. Christian

    1997-01-01

    Calcareous benthic foraminifera from four cores from the southern flank of the Skagerrak (NE North Sea) were investigated in order to estimate the response of this fossil group to climate fluctuations during the upper part of the Holocene. Q-mode factor analyses were carried out for the most abundant taxa. The results reveal C. laeuigata, H. baltllica, M. barleeanus, G. turgida, B. mal;yirintn, and U. yeregrirtn as most conm~on/importantta xa. In the upper part of all cores B. ...

  10. Foraminiferal assemblages behavior at the Messinian-Pliocene boundary in Eastern Tunisia

    Science.gov (United States)

    Gaaloul, Nadia; Rim, Temami; Razgallah, Saloua

    2014-05-01

    The microfaunal study of several boreholes drilled in Eastern Tunisia (western edge of the Mediterranean pelagian platform) has allowed the characterization of the Miocene-Pliocene boundary which has been previously well studied elsewhere in the Mediterranean basins but is still to be more understood within the Tunisian Mediterranean margin. Analyses of vertical and lateral evolution of benthonic and planktonic foraminifera between five boreholes belonging to the Gulf of Hammamet (Eastern Tunisia) revealed three distinctive palaeo-ecological depositional environments. - During the lower Messinian, benthonic foraminifera are abundant and show a great diversity in genus and species. They indicate marine settings with normal salinity and good oxygenation. Sub-reefal environment characterize this shallow water limestone platform; - The Upper Messinian is characterized by a general extinction of foraminifera (only few euryhalin organisms remain at the base of these series). This event corresponds to the Messinian salinity crisis and to the accumulation of evaporites in the Mediterranean basins. In the offshore of Eastern Tunisia, gypsum and anhydrites are deposited in a lagoonal environment and had a negative effect on the biological life. - During the Pliocene, limestones and clays overlay an erosional surface corresponding to the top of the Messinian deposits. This unconformity indicates the beginning of the Pliocene transgression which has led to a high diversity in planktonic and benthonic foraminifera. This new assemblage indicates open marine conditions.

  11. Benthic Foraminiferal Census Data from Louisiana Continental Shelf Cores, Gulf of Mexico

    Science.gov (United States)

    Osterman, Lisa E.; Kelly, Wendy S.; Ricardo, John P.

    2009-01-01

    An area of oxygen-depleted bottom- and subsurface-water (hypoxia = dissolved oxygen cores collected from the Continental Shelf of Louisiana (table 1), obtained as part of an initiative to investigate the geographic and temporal extent of hypoxia prior to 1985 in the Gulf of Mexico. Benthic foraminifers provide a method to track the development of hypoxia prior to 1985 (Blackwelder and others, 1996; Sen Gupta and others, 1996). Previous work (Osterman, 2003) has shown statistically that the relative occurrence of three low-oxygen-tolerant species represents the modern seasonal Louisiana hypoxia zone. The cumulative percentage of these three species (% Pseudononion atlanticum + % Epistominella vitrea, + % Buliminella morgani = PEB index of hypoxia) provides a way to investigate fluctuation in paleohypoxia. Interpretation of some of these cores is provided in Osterman and others (2005), Osterman and others (2008a,b), and Swarzenski and others (2008). Our hypothesis is that the increased relative abundance of PEB species in dated sediment cores accurately tracks past seasonal low-oxygen conditions on the Louisiana Shelf.

  12. Tracing subarctic Pacific water masses with benthic foraminiferal stable isotopes during the LGM and late Pleistocene

    Science.gov (United States)

    Cook, Mea S.; Ravelo, A. Christina; Mix, Alan; Nesbitt, Ian M.; Miller, Nari V.

    2016-03-01

    As the largest ocean basin, the Pacific helps to set the global climate state, since its circulation affects mean ocean properties, air-sea partitioning of carbon dioxide, and the distribution of global oceanic poleward heat transport. There is evidence that during the Last Glacial Maximum (LGM) the subarctic Pacific contained a better-ventilated, relatively fresh intermediate water mass above ~2000 m that may have formed locally. The source and spatial extent of this water mass is not known, nor do we know how formation of this water mass varied during Pleistocene glaciations with different orbital and ice sheet boundary conditions. Here we present a 0.5 My multi-species benthic stable isotope record from Site U1345 (1008 m) on the northern Bering slope and a 1.0 My record from U1339 (1868 m) from the Umnak Plateau in the southeastern basin. We find that the relatively well-ventilated low-δ18O intermediate water reaches 1000 m in the Bering Sea during MIS2, but that the hydrographic divide between this water mass and poorly-ventilated deep water was shallower than 1000 m for earlier glaciations. We also compare Bering Sea piston core and IODP Expedition 323 Uvigerina data from the Holocene and LGM with the modern hydrography, and to previously published profiles from the Okhotsk Sea and Emperor Seamounts. We find that the carbon and oxygen stable isotope signatures of well-ventilated water in the Bering and Okhotsk Seas are distinct, suggesting that there may have been intermediate water formation in both basins during the LGM.

  13. 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.

  14. 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. ...

  15. Inferring surface water equilibrium calcite δ18O during the last deglacial period from benthic foraminiferal records: Implications for ocean circulation

    Science.gov (United States)

    Amrhein, Daniel E.; Gebbie, Geoffrey; Marchal, Olivier; Wunsch, Carl

    2015-11-01

    The ocean circulation modifies mixed layer (ML) tracer signals as they are communicated to the deep ocean by advection and mixing. We develop and apply a procedure for using tracer signals observed "upstream" (by planktonic foraminifera) and "downstream" (by benthic foraminifera) to constrain how tracer signals are modified by the intervening circulation and, by extension, to constrain properties of that circulation. A history of ML equilibrium calcite δ18O (δ18Oc) spanning the last deglaciation is inferred from a least-squares fit of eight benthic foraminiferal δ18Oc records to Green's function estimated for the modern ocean circulation. Disagreements between this history and the ML history implied by planktonic records would indicate deviations from the modern circulation. No deviations are diagnosed because the two estimates of ML δ18Oc agree within their uncertainties, but we suggest data collection and modeling procedures useful for inferring circulation changes in future studies. Uncertainties of benthic-derived ML δ18Oc are lowest in the high-latitude regions chiefly responsible for ventilating the deep ocean; additional high-resolution planktonic records constraining these regions are of particular utility. Benthic records from the Southern Ocean, where data are sparse, appear to have the most power to reduce uncertainties in benthic-derived ML δ18Oc. Understanding the spatiotemporal covariance of deglacial ML δ18Oc will also improve abilities of δ18Oc records to constrain deglacial circulation.

  16. Paleobathymetric reconstruction of the Miocene "Venetian foothills" (NE Italy): a multidisciplinary approach based on foraminiferal assemblages and rhodolith facies

    Science.gov (United States)

    Mancin, N.; Ventura, M.; Barbieri, C.

    2003-04-01

    A paleobathymetric reconstruction, based on the integrated study of both foraminiferal assemblages and red-algal concretions (rhodoliths), has been carried out for the Venetian Foothill succession cropping out along the southern border of the Alpine chain (Veneto-Friuli Foreland System, NE Italy). The studied succession, up to 500 m thick, has been deposited into a shallow to deep water marine environment during the Aquitanian to Langhian time-interval, due to the combined effect of the Dinaric and Alpine tectonics and the eustatic sea-level changes. The main goals of this work are: i) to reconstruct the paleobathymetry of the Venetian foothill succession and, tentatively, ii) to relate the bathymetric evolution of the studied areas to the sea-level changes and to the history of the vertical motion ("geohistory") of the underlying substratum in response to tectonics and sedimentary load. The detected time-interval (Aquitanian to Langhian) is particularly important as it embraces the transition between the Dinaric and South-Alpine orogenetic phases. The main results can be summarised as follows: a paleobathymetric evolution has been observed for the studied succession from the Aquitanian to the Langhian. In particular a 40--60 m paleodepth has been determined for the Calcareniti di Castelcucco Fm. Moreover a peculiar depositional environment, such as an outer-shelf incised by submarine canyons and characterised by a relatively high water hydrodynamism, has been proposed for this formation on the basis of the rhodolith size (5--6 cm). An upper to lower neritic depth (from 0--100 to 100--200 m) has been obtained for the Siltiti dei Casoni and Arenarie di Libano Formations and for the Marne di Monte Bolago Fm., respectively. An upper bathyal depth (200--600 m) has been determined for the lower-middle part of the Marne di Monfumo Fm. Finally a gradually decreasing in depth has been observed, in particular a lower to upper neritic paleodepth (from 200--100 to 100--0 m

  17. Role of 12 S mitochondrial gene on dimorphism and coiling direction in benthic foraminiferal species Pararotalia nipponica

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.; Mazumder, A.; Kurtarkar, S.R.; Nigam, R.; Ganguly, A.

    in the intricacies of the molecular properties of the protoplasm. However, molecular systematic analyses of foraminifera are yet to start in India. Here, beginning has been made in this direction, by establishing foraminiferal culture program. For that, live...

  18. BENTHIC FORAMINIFERAL AND ITS ENVIRONMENTAL DEGRADATION STUDIES BETWEEN THE TSUNAMIGENIC SEDIMENTS OF MANDAPAM AND TUTICORIN, SOUTH EAST COAST OF INDIA

    Directory of Open Access Journals (Sweden)

    S. P. MOHAN

    2007-01-01

    Full Text Available The Gulf of Mannar is a transitional zone between the Arabian Sea and Indian Ocean proper and is connected with the Bay of Bengal through a shallow sill, the Palk Strait. The study area extends from Mandapam to Tuticorin on the southern coast of Tamil Nadu (India over a distance of 120 km. It is bound in the northeast by Rameshwaram Island, in the east by the Bay of Bengal, in the west by the Eastern and Western Ghats, and in the south by Tuticorin. A total of 36 sediment samples were collected from the beach (6 and the offshore (30 area in the study region. The offshore samples were collected at six transects keeping the stations at Mandapam (5 nos, Valinokkam (5 nos, Vaippar (5 nos, Vembar (5 nos, Kallar, (5 nos and Tuticorin (5 nos. Totally, 77 benthic foraminiferal species (Post-tsunami and varieties belonging to 39 genera, 13 families, 10 superfamilies and 4 suborders have been reported and illustrated. The following species are widely distributed in the pre and post-tsunami samples namely Spiroloculina communis, Quinqueloculina elongatum, Q.lamarckiana, Q. seminulum, Triloculina trigonula, Cibicides lobatululs, Ammonia beccarii, A. dentata, A.tepida, Elphidium crispum and Assilina ammonoides. Grain size studies shows the frequency curves vary from unimodal to bimodal in places of river discharge from the Vembar, Kallar, Vaippar and Tamiraparani, as a result of which an additional sub-population is deposited. At Mandapam and Tuticorin, the total species are increasing in the deeper depths whereas in Kallar there will be reverse trend which decreases with depth. Similarly, the living species also have the same trend at Vallinokkam. The scatter plot of salinity versus living species shows a positive correlation. The scatter plot of organic matter versus living species shows strong negative correlation and positive correlation with dead species showing a negative relation with the biomass. Further, the trend of organic matter vs. carbonate

  19. 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.

  20. Differential dissolution susceptibility in late Paleocene to early Eocene planktonic foraminiferal assemblages: comparing experimental and distributional data from Shatsky Rise (Pacific Ocean)

    Science.gov (United States)

    Nguyen, T. M. P.; Petrizzo, M. R.; Speijer, R. P.

    2009-04-01

    most dissolution-susceptible taxon, whereas Morozovella and especially Acarinina are less dissolution-prone. These results are also consistent with experimental data performed on planktonic foraminiferal assemblages from the PETM in Egypt (Nguyen et al., in prep.). In addition, various species of Acarinina show differential susceptibility, with A. soldadoensis being most resistant, followed by A. subsphaerica and A. nitida, respectively. Amongst Morozovella, in decreasing order of dissolution resistance we find M. aragonensis, M. subbotina, M. aequa, M. occlusa, M. pasionensis, M. acuta and M. velascoensis. Igorina pusilla and I. tadjkistanensis show a similar dissolution resistance. A dissolution ranking scheme and a new dissolution index are being developed on the basis of these data, which should allow for a more objective and quantitative evaluation of dissolution phenomena in early Paleogene planktonic foraminiferal assemblages. References: 1. Nguyen T. M. P. et al., in prep. Experimental dissolution of a foraminiferal assemblage from the Paleocene-Eocene Thermal Maximum at Dababiya, Egypt: implications for paleoenvironmental reconstructions. 2. Petrizzo, M.R., 2007. The onset of the Paleocene-Eocene Thermal Maximum (PETM) at Sites 1209 and 1210 (Shatsky Rise, Pacific Ocean) as recorded by planktonic foraminifera. Marine Micropaleontology, 63(3-4): 187-200. 3. Petrizzo, M.R., Leoni, G., Speijer, R.P., De Bernardi, B. and Felletti, F., 2008. Dissolution susceptibility of some Paleogene planktic foraminifera from ODP site 1209 (Shatsky Rise, Pacific Ocean). Journal of Foraminiferal Research, 38(4): 81-95.

  1. Impact of organic matter source and quality on living benthic foraminiferal distribution on a river-dominated continental margin: A study of the Portuguese Margin.

    Science.gov (United States)

    Bonnin, Jerome; Dessandier, Pierre-Antoine; Kim, Jung-Hyun; Deflandre, Bruno; Gremare, Antoine; Sinninghe-Damsté, Jaap

    2016-04-01

    Quinqueloculina seminula) adapted to environments characterized by high OM quality (high fresh chlorophyll (Chl-a/Phaeo) and available amino acids (EHAA/THAA)). The benthic foraminiferal distribution is mostly controlled by three environmental parameters, i.e. TOC (quantity), EHAA/THAA (quality), and δ13CTOC (source). Hence, this study clearly highlights that the quantitative and qualitative inputs of OM and its source are the most important factors controlling the living benthic foraminiferal distribution with clear differences between the different rivers influence. This study also suggests a good tolerance of several species for river discharges where the OM quality.

  2. Palaeoceanographic implications of abundance and mean proloculus diameter of benthic foraminiferal species Epistominella exigua in sub-surface sediments from distal Bay of Bengal fan

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.; Nigam, R.; Barreto, L.

    from the distal Bay of Bengal fan sediments, to infer past bottom water conditions (figure 1). 2. Epistominella exigua Epistominella exigua is a trochospirally coiled, calcareous species with smooth surface (Murray 1991). E. exigua is a sporadically... J and Giese M 1995 Deep-sea foraminifera in the South Atlantic Ocean: Eco- logy and assemblage generation; Mar. Micropaleontol. 41 342–358. Murray J W 1991 Ecology and Paleoecology of Benthic Foraminifera. John Wiley, New York and Longman Sci...

  3. Contrasting responses of coral reef fauna and foraminiferal assemblages to human influence in La Parguera, Puerto Rico

    Science.gov (United States)

    Coral reef biota including stony corals, sponges, gorgonians, fish, benthic macroinvertebrates and foraminifera were surveyed in coastal waters near La Parguera, in southwestern Puerto Rico. The goal was to evaluate sensitivity of coral reef biological indicators to human distur...

  4. 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.

  5. Modern and late Holocene foraminiferal record of restricted environmental conditions in the Albufeira Lagoon, SW Portugal

    OpenAIRE

    Alday, M.; Cearreta, A.; Freitas, M.C.; Andrade, C.

    2013-01-01

    Benthic foraminifera from twenty stations sampled twice were analyzed in order to examine the environmental conditions of the Albufeira coastal lagoon. Foraminiferal assemblages show an increase in the abundance, species diversity and allochthonous content seaward. Three zones have been defined: the inner and more restricted area of the lagoon where the main species are the euryhaline Ammonia tepida and Haynesina germanica; these two species together with Bulimina gibba and Brizalina britanni...

  6. Temporal variability of live (stained benthic foraminiferal faunas in a river-dominated shelf – Faunal response to rapid changes of the river influence (Rhône prodelta, NW Mediterranean

    Directory of Open Access Journals (Sweden)

    E. Legrand

    2012-04-01

    Full Text Available In the context of the French research project CHACCRA (Climate and Human-induced Alterations in Carbon Cycling at the River-seA connection, living (rose Bengal-stained benthic foraminifera were investigated at two stations (24 and 67 m depth in the Rhône prodelta (NW Mediterranean, Gulf of Lions. The aim of this study was to precise the response of benthic foraminiferal faunas to temporal changes of the Rhône River inputs (e.g. organic and terrigeneous material. Each site was sampled in April 2007, September 2007, May 2008 and December 2008, permitting to observe foraminiferal faunas of the 63–150 and >150 μm size fractions under a wide range of environmental conditions. Obvious variations in foraminiferal faunal composition were observed during the four investigated periods at the shallowest Station A located in the close vicinity of the Rhône River mouth. After major Rhône River flood events, different colonisation stages were observed with foraminiferal faunas responding with an opportunistic strategy few days to weeks after the creation of a peculiar sedimentary environment (Leptohalysis scottii, May 2008 or high organic matter supplies (Ammonia tepida, December 2008. Under more stable conditions, relatively diverse and equilibrated faunas grew in the sediments. Species benefited from noticeable input of riverine phytodetritus to the sediment during spring bloom conditions (April 2007; e.g. Bolivina dilatata, Nonionella stella, Stainforthia fusiformis, or high amounts of still bio-available organic matter under more oligotrophic conditions (September 2007; e.g. Ammonia tepida, Psammosphaera fusca. The reduced influence of the Rhône River input at the farther Station N led to less contrasted environmental conditions during the four sampling periods, and so to less obvious variations in foraminiferal faunal composition. During reduced riverine influence (i.e. low Rhône discharge, species able to feed on fresh phytodetritus (e

  7. Palaeoceanographic implications of abundance and mean proloculus diameter of benthic foraminiferal species Epistominella exigua in sub-surface sediments from distal Bay of Bengal fan

    Indian Academy of Sciences (India)

    R Saraswat; R Nigam; Lea Barreto

    2005-10-01

    Temporal variation in abundance and mean proloculus diameter of the benthic foraminiferal species Epistominella exigua has been reconstructed over the last ∼ 50,000 yr BP,from a core collected from the distal Bay of Bengal fan,to assess its potential application in palaeoceanographic reconstruction studies.The down-core variation shows significant change in abundance of E. exigua during the last ∼50,000 yr BP.In view of the present day abundance of this species from areas with strong seasonal organic matter supply, we conclude that at ∼7, ∼22, ∼33 and ∼46 kyr BP, strong seasonality prevailed in the distal Bay of Bengal fan,probably indicating either strong or prolonged north–east monsoon or weakened south–west monsoon.For the first time,a strong correlation is observed in abundance and mean proloculus diameter of E. exigua Based on coherent variation in mean proloculus diameter and abundance,it is postulated that mean proloculus diameter can also be used to infer increased seasonality in organic matter production,thus variation in strength or duration of monsoon.Thus,this study establishes that the down-core variation in the abundance and mean proloculus diameter of Epistominella exigua can be used to infer past climatic variations from the distal Bay of Bengal fan.

  8. Messinian paleoenvironmental evolution in the lower Guadalquivir Basin (SW Spain) based on benthic foraminifera.

    OpenAIRE

    Pérez-Asensio, J.N.; Aguirre, J.; Schmiedl, G.; Civis Llovera, J.

    2012-01-01

    Benthic foraminiferal assemblages of a drill core from the lower Guadalquivir Basin (northern Gulf of Cádiz, SW Spain) have been analyzed in order to reconstruct the paleoenvironmental evolution in the vicinity of the Betic seaways during the Messinian. The core consists of marine sediments ranging from the latest Tortonian to the early Pliocene. Changes in the abundance of certain marker species, planktonic/benthic ratio (P/B ratio), paleodepth estimated with a transfer function, content of ...

  9. Comparison of ecological diversity and species composition of macroalgae, benthic macroinvertebrates, and fish assemblages between two tropical rocky reefs

    OpenAIRE

    Verónica C. García-Hernández; Héctor Reyes-Bonilla; Balart, Eduardo F; Eduardo Ríos-Jara; Lluch-Cota, Salvador E.; Elisa Serviere-Zaragoza

    2014-01-01

    Within the marine environment, the rocky shores are recognized for their high species diversity and particularly transitional zones represent areas of biotic mix, promoted by historical and ecological natural variations that allow the presence of taxa from different regions and which present dissimilar biological traits. An extensive survey describes the benthic macroalgae, macroinvertebrates (molluscs, crustaceans, and echinoderms), and fish assemblages at two rocky reefs, Islas Marietas and...

  10. 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

  11. 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.

  12. Dynamics of Coral Reef Benthic Assemblages of the Abrolhos Bank, Eastern Brazil: Inferences on Natural and Anthropogenic Drivers

    OpenAIRE

    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.; Fernando Z Gibran; Güth, Arthur Z.; Sumida, Paulo Y. G.; Oliveira, Nara L.; Kaufman, Les; Minte-Vera, Carolina V.

    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. Benthi...

  13. 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

  14. The role of benthic foraminifera in the benthic nitrogen cycle of the Peruvian oxygen minimum zone

    Directory of Open Access Journals (Sweden)

    N. Glock

    2012-12-01

    Full Text Available The discovery that foraminifera are able to use nitrate instead of oxygen as energy source for their metabolism has challenged our understanding of nitrogen cycling in the ocean. It was evident before that only prokaryotes and fungi are able to denitrify. Rate estimates of foraminiferal denitrification were very sparse on a regional scale. Here, we present estimates of benthic foraminiferal denitrification rates from six stations at intermediate water depths in and below the Peruvian oxygen minimum zone (OMZ. Foraminiferal denitrification rates were calculated from abundance and assemblage composition of the total living fauna in both, surface and subsurface sediments, as well as from individual species specific denitrification rates. A comparison with total benthic denitrification rates as inferred by biogeochemical models revealed that benthic foraminifera account for the total denitrification on the shelf between 80 and 250 m water depth. They are still important denitrifiers in the centre of the OMZ around 320 m (29–56% of the benthic denitrification but play only a minor role at the lower OMZ boundary and below the OMZ between 465 and 700 m (3–7% of total benthic denitrification. Furthermore, foraminiferal denitrification was compared to the total benthic nitrate loss measured during benthic chamber experiments. Foraminiferal denitrification contributes 1 to 50% to the total nitrate loss across a depth transect from 80 to 700 m, respectively. Flux rate estimates ranged from 0.01 to 1.3 mmol m−2 d−1. Furthermore we show that the amount of nitrate stored in living benthic foraminifera (3 to 705 µmol L−1 can be higher by three orders of magnitude as compared to the ambient pore waters in near surface sediments sustaining an important nitrate reservoir in Peruvian OMZ sediments. The substantial contribution of foraminiferal nitrate respiration to total benthic nitrate loss at the Peruvian margin

  15. Cold-water coral habitats of Rockall and Porcupine Bank, NE Atlantic Ocean: Sedimentary facies and benthic foraminiferal assemblages

    OpenAIRE

    Smeulders, G.G.B.; K. A. Koho; de Stigter, H.C.; Mienis, F.; Haas, H.; Weering, T.C.E. van

    2014-01-01

    The extent of the cold-water coral mounds in the modern ocean basins has been recently revealed by new state-of-the-art equipment. However, not much is known about their geological extent or development through time. In the facies model presented here seven different types of seabed substrate are distinguished, which may be used for reconstruction of fossil coral habitats. The studied substrates include: off-mound settings, (foram) sands, hardgrounds, dead coral debris, and substrates charact...

  16. Recent benthic foraminifera from the Caribbean continental slope and shelf off west of Colombia

    Science.gov (United States)

    Fiorini, Flavia

    2015-07-01

    A quantitative benthic foraminiferal analysis was conducted on 30 sea-floor sediment samples distributed along the continental slope and shelf in Fuerte Area (Colombian Caribbean), between 39 and 2469 m water depth. The aims of the research were to provide data on the distribution of southwestern Caribbean Recent benthic foraminifera, to estimate changes in the foraminiferal distribution related to the bathymetry and the characteristics of the substrate, to define a data-bank on distribution of recent tropical benthic foraminifera from the southwestern Caribbean, to provide reference on foraminiferal distribution that can be used in bathymetric reconstructions of ancient environments. Three different assemblages corresponding to three different environments were identified by cluster analysis. Assemblage A, characterized by variable percentages of porcellaneous, hyaline and agglutinated benthic foraminifera indicative of shelf environments. Assemblage B, dominated by calcareous hyaline foraminifera mainly composed of infaunal foraminifera corresponding to upper bathyal, marine conditions. Assemblage C, composed by agglutinated and calcareous hyaline foraminifera characteristic of normal deep-water marine environments.

  17. An Intermediate Water Mass Geometry for the Glacial South Atlantic From Benthic Foraminiferal Cd/Ca and δ13C

    Science.gov (United States)

    Makowski, M. C.; Oppo, D. W.; Curry, W. B.

    2002-12-01

    Cd/Ca and δ13C of benthic foraminifera (from Brazilian Margin marine sediment cores spanning a water depth of 441 to 1627 meters) were used to reconstruct the shallow to intermediate water mass geometry of the South Atlantic during the last glacial maximum (LGM). Additionally, paired Cd and δ13C results were used to estimate the portion of the δ13C signal attributable to air/sea exchange of CO2 (δ13Cas), which can be used as a conservative water mass tracer. Three distinct water masses were identified using this approach. A high-nutrient water mass was centered at 1105 m and was bordered above and below by low-nutrient water masses. The nutrient-poor water mass at about 1600 m was identified as Glacial North Atlantic Intermediate Water (GNAIW), which is shown to extend at least to 27oS in the glacial Atlantic. The shallowest water mass was most likely Central Water derived from the South Atlantic gyre, as it is in the modern ocean. However, glacial δ13Cas values for this water mass were lower than modern estimates from nearby GEOSECS Station 57 δ13C and PO4 data, indicating that it formed in a different manner at the LGM. The high-nutrient water mass centered at 1105 m also had lower δ13Cas than modern Upper Circumpolar Deep Water (UCDW), which resides at about this depth today. It exhibited an average glacial δ13Cas value of 0.21‰ , compared to approximately 0.83‰ calculated for modern UCDW at GEOSECS Station 57, implying a different formation mechanism at the LGM. These reduced glacial air/sea exchange values suggest that the glacial, high-nutrient water mass was poorly ventilated at its source region and may have been formed from different source waters. A comparison of glacial intermediate waters from the Brazil Margin and other oceans also implies that a uniquely formed version of UCDW was present in the South Atlantic. δ13Cas values for the glacial high-nutrient water mass are lower by 0.49-1.33‰ than those for waters in the Sub

  18. Ammolagena clavata (Jones and Parker, 1860), an agglutinated benthic foraminiferal species - first report from the Recent sediments, Arabian Sea, Indian Ocean region

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Mazumder, A.; Saraswat, R.

    The rare presence of the agglutinated foraminiferal species Ammolagena clavata is presented for the first time from the Recent sediments of the Indian Ocean region. This species has previously been reported in Recent sediments from all other oceans...

  19. 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

  20. 100 Years of benthic foraminiferal history on the inner Texas shelf inferred from fauna and stable isotopes: Preliminary results from two cores

    Science.gov (United States)

    Strauss, Josiah; Grossman, Ethan L.; Carlin, Joseph A.; Dellapenna, Timothy M.

    2012-04-01

    Coastal regions, such as the Texas-Louisiana shelf, are subject to seasonal hypoxia that strongly depends on the magnitude of freshwater discharge from local and regional river systems. We have determined benthic foraminiferal fauna and isotopic compositions in two 210Pb dated box cores (BR4 and BR5) to examine the evidence for nearshore hypoxia and freshwater discharge on the Texas shelf during the last 100 years. The 210Pb chronologies of both cores reveal sedimentation rates of 0.2 and 0.1 cm yr-1, translating to ˜60 and ˜90 year records. The fauna of both cores were almost exclusively composed of Ammonia parkinsoniana and Elphidium excavatum, indicating euryhaline ambient waters. The Ammonia-Elphidium (A-E) index, a qualitative measure of low oxygen conditions, shows an increase from values between 20 and 50 to near 100 in both cores, suggesting low oxygen conditions between 1960 and the core top. Between 1950 and 1960 (9-10 cm), low A-E values in BR4 coincide with high δ18O and δ13C values greater than 0‰ and -1‰ respectively. This event corresponds to severe drought (the Texas Drought of Record) over the Brazos River drainage basin and considerably reduced river discharge from 1948 to 1957. High A-E values prior to this event imply low-oxygen conditions were prevalent prior to anthropogenic exacerbation of Louisiana shelf hypoxia and at least since the dredging of a new Brazos River delta in 1929. Elphidium excavatum δ13C values are very low (-4‰) and indicative of significant vital effect. The δ13C values of A. parkinsoniana average -3‰ and exhibit little variability, most likely reflecting pore waters influenced by aerobic and anaerobic respiration. The association of lowered Brazos River discharge with more oxygenated shelf bottom waters suggests Brazos River discharge and shelf hypoxia are linked, but the influence of Mississippi-Atchafalaya discharge can also contribute to shelf stratification.

  1. Correlations between benthic habitats and demersal fish assemblages — A case study on the Dogger Bank (North Sea)

    Science.gov (United States)

    Sell, Anne F.; Kröncke, Ingrid

    2013-07-01

    The interdependence between groundfish assemblages and habitat properties was investigated on the Dogger Bank in the North Sea. Abiotic habitat parameters considered included topography, hydrographic conditions, sediment composition, and the biotic habitat variable the prevailing benthic invertebrates. Distinct epi- and infauna communities occurred at different locations on the Dogger Bank. Fish assemblages were clearly linked to both the biotic and abiotic habitat characteristics. Overall, fish and benthic communities revealed similar spatial distribution, represented in the respective clusters of characteristic and abundant species. Distribution patterns corresponded with the prevailing abiotic conditions such as depth and sediment composition, which appear to relate to autecological preferences of individual species. The apparently most generalist species, grey gurnard (Eutrigla gurnardus) and dab (Limanda limanda) occurred at all stations and dominated in terms of biomass in most cases. The absolute numbers of grey gurnards were related to the abundance of suitable prey, invertebrate and fish species, which stomach analyses revealed as part of the diet in an independent study during the same research cruise. Haddock (Melanogrammus aeglefinus) and whiting (Merlangius merlangus) were only abundant at deep stations along the flanks of the bank. The occurrence of lemon sole (Microstomus kitt), American plaice (Hippoglossoides platessoides) and cod (Gadus morhua) was also positively correlated with depth, whereas especially lesser weever (Echiichthys vipera), sandeel species and solenette (Buglossidium luteum) occurred predominantly at the shallower sites. At the same time, individual fish species such as solenette and lesser weever were associated with high densities of selected epi- or infauna species.

  2. Stable-isotope analysis of a deep-sea benthic-fish assemblage: evidence of an enriched benthic food web.

    Science.gov (United States)

    Boyle, M D; Ebert, D A; Cailliet, G M

    2012-04-01

    In this study, fishes and invertebrates collected from the continental slope (1000 m) of the eastern North Pacific Ocean were analysed using stable-isotope analysis (SIA). Resulting trophic positions (T(P) ) were compared to known diets and habitats from the literature. Dual isotope plots indicated that most species groups (invertebrates and fishes) sorted as expected along the carbon and nitrogen axes, with less intraspecific variability than interspecific variability. Results also indicated an isotopically distinct benthic and pelagic food web, as the benthic food web was more enriched in both nitrogen and carbon isotopes. Trophic positions from SIA supported this finding, resulting in the assignment of fishes to different trophic positions from those expected based on published dietary information. These differences can be explained largely by the habitat of the prey and the percentage of the diet that was scavenged. A mixing model estimated dietary contributions of prey similar to those of the known diet of Bathyraja trachura from stomach-content analysis (SCA). Linear regressions indicated that trophic positions calculated from SIA and SCA, when plotted against B. trachura total length for 32 individuals, exhibited similar variation and patterns. Only the T(P) from SCA yielded significant results (stomach content: P 0·05). PMID:22497394

  3. Effects of heavy metals pollution on benthic foraminifera assemblage: the Gulf of Gabes, Tunisia

    Science.gov (United States)

    Ayadi, Najla; Zghal, Ihsen; Bouzid, Jalel; Abdennaceur Ouali, Jamel

    2014-05-01

    Benthic foraminifera are amongst the most abundant protists found in huge marine and brackish water habitat. During the last few decades, many researches had been focused on using benthic foraminifera as bioindicators of marine pollution caused by industrial, domestic and agricultural waste, oil or heavy metal contamination. The aim of this research is to investigate heavy metals pollution in superficial sediments in two industrial locations at the Gulf of Gabes and to examine the reaction of benthic foraminifera towards metallic concentration. The Gulf of Gabes, located on the eastern coast of Tunisia, is regarded as an extremely vital zone and considered as one of the most important area for fishing in the country. During last years, the coastal area of this region had known an important demographic and industrial development, leading to the presence of uncontrolled discharge. Fifteen superficial sediment samples were collected along the coastline of Skhira and Ghannouch- Gabes. They have been analyzed for Al, Cd, Cr, Cu, Pb, and Zn concentrations as well as for the species composition of benthic foraminifera. Results show three levels of metallic contamination with high concentration of cadmium and zinc. Thirty five benthic foraminifera species were identified. Ammonia parkinsoniana, Ammonia beccarii, Peneroplis planatus, Triloculina trigonula and Adelosina longirostraare are the most abundant and common species. Increasing pollution results in a lower species diversity as well as population density, with the presence of a barren zone, and more frequent abnormal specimens. A complementary statistical analysis (PCA/FA and matrix correlation) shows that heavy metals are resulting from the same anthropogenic source and negative correlation between faunal parameters (density and diversity) and pollutants concentrations.

  4. Coral Reefs at the Northernmost Tip of Borneo: An Assessment of Scleractinian Species Richness Patterns and Benthic Reef Assemblages.

    Directory of Open Access Journals (Sweden)

    Zarinah Waheed

    Full Text Available The coral reefs at the northernmost tip of Sabah, Borneo will be established under a marine protected area: the Tun Mustapha Park (TMP by the end of 2015. This area is a passage where the Sulu Sea meets the South China Sea and it is situated at the border of the area of maximum marine biodiversity, the Coral Triangle. The TMP includes fringing and patch reefs established on a relatively shallow sea floor. Surveys were carried out to examine features of the coral reefs in terms of scleractinian species richness, and benthic reef assemblages following the Reef Check substrate categories, with emphasis on hard coral cover. Variation in scleractinian diversity was based on the species composition of coral families Fungiidae (n = 39, Agariciidae (n = 30 and Euphylliidae (n = 15. The number of coral species was highest at reefs with a larger depth gradient i.e. at the periphery of the study area and in the deep South Banggi Channel. Average live hard coral cover across the sites was 49%. Only 7% of the examined reefs had > 75% hard coral cover, while the majority of the reef sites were rated fair (51% and good (38%. Sites with low coral cover and high rubble fragments are evidence of blast fishing, although the observed damage appeared old. Depth was a dominant factor in influencing the coral species composition and benthic reef communities in the TMP. Besides filling in the information gaps regarding species richness and benthic cover for reef areas that were previously without any data, the results of this study together with information that is already available on the coral reefs of TMP will be used to make informed decisions on zoning plans for conservation priorities in the proposed park.

  5. Coral Reefs at the Northernmost Tip of Borneo: An Assessment of Scleractinian Species Richness Patterns and Benthic Reef Assemblages

    Science.gov (United States)

    Waheed, Zarinah; van Mil, Harald G. J.; Syed Hussein, Muhammad Ali; Jumin, Robecca; Golam Ahad, Bobita; Hoeksema, Bert W.

    2015-01-01

    The coral reefs at the northernmost tip of Sabah, Borneo will be established under a marine protected area: the Tun Mustapha Park (TMP) by the end of 2015. This area is a passage where the Sulu Sea meets the South China Sea and it is situated at the border of the area of maximum marine biodiversity, the Coral Triangle. The TMP includes fringing and patch reefs established on a relatively shallow sea floor. Surveys were carried out to examine features of the coral reefs in terms of scleractinian species richness, and benthic reef assemblages following the Reef Check substrate categories, with emphasis on hard coral cover. Variation in scleractinian diversity was based on the species composition of coral families Fungiidae (n = 39), Agariciidae (n = 30) and Euphylliidae (n = 15). The number of coral species was highest at reefs with a larger depth gradient i.e. at the periphery of the study area and in the deep South Banggi Channel. Average live hard coral cover across the sites was 49%. Only 7% of the examined reefs had > 75% hard coral cover, while the majority of the reef sites were rated fair (51%) and good (38%). Sites with low coral cover and high rubble fragments are evidence of blast fishing, although the observed damage appeared old. Depth was a dominant factor in influencing the coral species composition and benthic reef communities in the TMP. Besides filling in the information gaps regarding species richness and benthic cover for reef areas that were previously without any data, the results of this study together with information that is already available on the coral reefs of TMP will be used to make informed decisions on zoning plans for conservation priorities in the proposed park. PMID:26719987

  6. Temporal variability in discharge and benthic macroinvertebrate assemblages in a tropical glacier-fed stream

    DEFF Research Database (Denmark)

    Jacobsen, Dean; Andino, Patricio; Calvez, Roger;

    2014-01-01

    Abstract High flows are major disturbances in streams and cause benthic communities to vary temporally. Meltwater runoff in glacier-fed streams at temperate–arctic latitudes primarily follows a strong seasonal pattern. In contrast, such streams at the equator show less seasonal, but more......-pronounced diel variability in discharge that tracks a year-round diurnal melting–nocturnal freezing cycle of glaciers. Consequently, qualitative and quantitative differences in temporal variability of macrobenthos communities should be expected between high-latitude and tropical glacier-fed streams. We explored...... temporal variability in density, taxon richness, and community composition of benthic macroinvertebrates and analyzed community responses to flow events at 3 sites along a glacier-fed stream in equatorial Ecuador (0.05, 1.6, and 4.3 km from the glacier front). We obtained continuous flow recordings...

  7. Benthic Macrofaunal Assemblage in the Arid Zone Mangroves of Gulf of Kachchh - Gujarat

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The total benthic macrofauna consisting of 62 species in 5 groups, viz. crustaceans (18), gastropods (17), bivalves (16), polychaetes (9) and fishes (2), was recorded in western Kachchh mangroves near Gujarat. The population densities of benthic macrofauna ranged from 424 to 2393 ind.m-2, the diversity ranged from 1.84 to 2.45 bits ind.-1, the richness varied between 0.82 and 0.98, and the evenness varied between 0.64 and 0.81. Two maximum diversity values were recorded during winter and summer. The salinity ranged from 34 to 44, temperature varied between 17 and 37 ℃, and the acidity ranged from 7 to 8.9.

  8. A comparative analysis of benthic nematode assemblages from Zostera noltii beds before and after a major vegetation collapse

    Science.gov (United States)

    Materatski, Patrick; Vafeiadou, Anna-Maria; Ribeiro, Rui; Moens, Tom; Adão, Helena

    2015-12-01

    Benthic nematodes are widely regarded as very suitable organisms to monitor potential ecological effects of natural and anthropogenic disturbances in aquatic ecosystems. During 2008, the seagrass beds of Zostera noltii located in the Mira estuary (SW Portugal) disappeared completely. However, during 2009, slight symptoms of natural recovery were observed, a process which has since evolved intermittently. This study aims to investigate changes in patterns of nematode density, diversity, and trophic composition between two distinct habitat conditions: "before" the collapse of seagrass beds, and during the early recovery "after" the seagrass habitat loss, through the analysis of: i) temporal and spatial distribution patterns of nematode communities, and ii) the most important environmental variables influencing the nematode assemblages. The following hypotheses were tested: i) there would be differences in nematode assemblage density, biodiversity and trophic composition during both ecological conditions, "before" and "after"; and ii) there would be differences in nematode assemblage density, biodiversity and trophic composition at different sampling occasions during both ecological conditions. Nematode density and diversity were significantly different between the two ecological situations. A higher density was recorded before, but a higher diversity was evident after the collapse of Z. noltii. In spite of the disturbance caused by the seagrass habitat loss in the Mira estuary, the nematode trophic composition did not significantly differ between the before and after seagrass collapse situations. Despite the significant differences found among sampling occasions, a consistent temporal pattern was not evident. The response of nematode communities following this extreme event exhibited considerable resistance and resilience to the new environmental conditions.

  9. Benthic faunal assemblages from the Holocene middle shelf of the South Evoikos Gulf, central Greece, and their palaeoenvironmental implications

    Science.gov (United States)

    Asimina Louvari, Markella; Tsourou, Theodora; Drinia, Hara; Anastasakis, George

    2013-04-01

    South Evoikos Gulf is an elongate, WNW - ESE trending basin, 60 km long and 15 km wide. Its floor slopes towards the south-east where the basin connects with the Aegean Sea across a 55 m deep sill. The hydrographic network of the area is characterized by Asopos river the small Lilas River and some other ephemeral streams. A sedimentary record spanning the last 13000 calyr BP was recovered at N 38°12'23.1228" E 24°8'14.2404", water depth 70 m, in this gulf. A total of 52 samples from the lower half of the core were quantitatively analyzed for micropalaeontological (benthic foraminifera and ostracods) study in order to reconstruct palaeoenvironmental conditions. This work contributes to the evaluation of the modern environmental problems in South Evoikos Gulf (hypoxia, ecosystem changes, subaquatic vegetation die-off, metal pollution) within the context of the palaeoenvironmental record. In the investigated core, the benthic microfaunal assemblages indicate a marine coastal environment with a gradual transition from a circalittoral to an infralittoral restricted environment. The basal part of the record is characterized by Haynesina depressula Assemblage, which is composed of Haynesina depressula, Textularia agglutinans and Bulimina aculeata.The abundance of Haynesina depressula could be associated with normal marine conditions, but always with periodic brackish water influence. The species composed this assemblage, which are almost all typically infaunal, characterize sediments with a high or medium-high muddy fraction, rich in organic matter available for the organisms that live within the sediment, and low salinity bottom water. Samples from the upper unit of the core indicate a nearshore, inner-shelf facies less than 50 m deep. Common inner-shelf species in these samples include Ammonia beccarii together with Bulimina marginata (Sgarrella & Moncharmont Zei, 1993). The highest abundance of A. beccarii is found between 15 and 20 m water-depth in samples with

  10. Reconstructing pre-impact baseline conditions using benthic foraminifera in an area of increasing petroleum exploration activities

    Science.gov (United States)

    Dijkstra, Noortje; Junttila, Juho; Aagaard-Sørensen, Steffen

    2016-04-01

    While macrofauna is traditionally used to bio-monitor to state of the ecosystem, benthic foraminifera have large potential for bio-monitoring as well. As their tests stay preserved in the sedimentary archive it is possible to reconstruct pre-impacted conditions, by studying foraminiferal assemblages in sediment cores. The use of foraminiferal faunas as bio-monitoring tools is complicated by the natural variability. Therefore, detailed site specific studies are needed, to understand the range of natural variability of the area of interest. This study characterizes the natural variability in the Bjørnøyrenna-Ingøydjupet area in the Southern Barents Sea. The Southern Barents Sea is a relatively un-impacted and uncontaminated area, however petroleum industry related activities are expected to increase in the near future. This makes the area a valuable natural laboratory to establish pre-impacted baselines for future seabed monitoring programs. Benthic foraminiferal assemblages were examined at high resolution in sediment cores and compared to sediment properties and metal concentrations. Species associated to temperate water masses dominate in the southern part of the study area, while species associated to cooler water masses increase in abundance towards the north into Bjørnøyrenna. Additionally, the foraminiferal assemblages might reflect climatic oscillations on both millennial and decadal time scales. Patterns in the calcareous foraminiferal assemblages suggest an enhanced food supply as a result of increased Atlantic Water inflow through the region during the last 150 years. Sediment TOC content has been linked with variable inflow of Atlantic Water. A strong positive correlation was observed between TOC content with metal content in the cores. It is therefore essential to consider the role of natural variability of oceanographic conditions when using benthic foraminiferal assemblages to monitor for potential anthropogenic impacts on the environment. This

  11. Paleocene-Early Eocene larger foraminiferal biostratigraphy of Yemen and Oman

    Science.gov (United States)

    Di Carlo, M.; Serra-Kiel, J.; Pignatti, J.

    2012-04-01

    The Paleogene larger foraminiferal biostratigraphy is today rather well assessed for the Tethyan domain. In order to contribute to the full integration of the Middle-East in the widely employed Shallow Benthic Zonation, a preliminary report on the Paleocene-Early Eocene larger foraminiferal assemblages from Yemen and Oman is provided here. The sections investigated in Yemen range in age from the Upper Cretaceous to the Oligocene. The Paleogene of Yemen is widely affected by dolomitization and only by analyzing over 1,700 thin sections from 60 stratigraphic sections (mainly from Hadramaut and Socotra) it has been possible to adequately investigate the fossil assemblages. In contrast, the deposits from northern Oman are characterized by rich and extraordinarily well-preserved Paleocene-Lower Eocene larger foraminiferal assemblages. This preliminary report focuses mainly on the Paleocene-Early Eocene deposits of the Umm-er-Radhuma formation. The Paleocene-Lower Eocene assemblages are characterized by strong affinities with northern Somalia. Hyaline forms such as Daviesina khatiyahi, Miscellanea gr. rhomboidea/dukhani, M. miscella, Saudia, Sakesaria, Lockhartia, Ranikothalia, Dictyokathina largely prevail in SBZ 3-4 deposits. Nummulites, Ranikothalia and Daviesina ruida characterize the Lower Ypresian. Subordinately, porcelaneous forms such as "Taberina" daviesi and conical agglutinated (Daviesiconus) also occur; alveolinids (such as Alveolina vredenburgi and A. decipiens) are relatively abundant in the basal Lower Ypresian of Socotra. In contrast to the coeval deposits from Yemen, the Paleocene section of Oman (Wadi Duqm, Abat-Tiwi platform) yields very well-preserved larger foraminiferal assemblages and agglutinated and porcelaneous forms are well represented. The occurrence of abundant Globoreticulina paleocenica is noteworthy along with an as yet undescribed Lacazinella species. The co-occurrence of Coskinon sp., "Plumokathina dienii", Dictyoconus turriculus and

  12. Evaluation of benthic macroinvertebrate assemblage for disturbance zonation in urban rivers using multivariate analysis: Implications for river management

    Science.gov (United States)

    Shah, Ram Devi Tachamo; Shah, Deep Narayan

    2013-08-01

    River pollution has tremendously increased in the major cities of South Asia, where the rivers have become a repository for domestic, agricultural, municipal and industrial wastes. This study presents the evaluation of benthic macroinvertebrate assemblage as a means of assessing ecological status, determining different disturbance zones and identifying environmental variables and stressors that deteriorate the river ecosystem. In total, 20 sites in 36-km stretch of the main stem of the Bagmati River and 7 sites on its tributaries were selected for sampling in the post-monsoon and pre-monsoon seasons during the time period 2008-2010. The Ganga River System Biotic Score (GRSbios) index was applied to determine the ecological status. The ecological status of the different Bagmati River stretches ranged from reference (Class 1) to extremely polluted (Class 5). We identified three types of disturbance zones along the river, ranging from minimally polluted to extremely polluted. A river corridor survey was conducted to identify any river stressing factors, revealing a sharp deterioration of the river from upstream to downstream with increasing concentrations of chloride and ortho-phosphate phosphorus. Effluents and Activities and Facilities were found to be the major stressing factors to the river ecosystem. The information gained should help water managers find the most time-efficient and cost-effective measures to address river degradation.

  13. Evaluation of benthic macroinvertebrate assemblage for disturbance zonation in urban rivers using multivariate analysis: Implications for river management

    Indian Academy of Sciences (India)

    Ram Devi Tachamo Shah; Deep Narayan Shah

    2013-08-01

    River pollution has tremendously increased in the major cities of South Asia, where the rivers have become a repository for domestic, agricultural, municipal and industrial wastes. This study presents the evaluation of benthic macroinvertebrate assemblage as a means of assessing ecological status, determining different disturbance zones and identifying environmental variables and stressors that deteriorate the river ecosystem. In total, 20 sites in 36-km stretch of the main stem of the Bagmati River and 7 sites on its tributaries were selected for sampling in the post-monsoon and pre-monsoon seasons during the time period 2008–2010. The Ganga River System Biotic Score (GRSbios) index was applied to determine the ecological status. The ecological status of the different Bagmati River stretches ranged from reference, class 1 to class 5 (extremely polluted). We identified three types of disturbance zones along the river, ranging from minimally polluted to extremely polluted. A river corridor survey was conducted to identify any river stressing factors, revealing a sharp deterioration of the river from upstream to downstream with increasing concentrations of chloride and ortho-phosphate phosphorus. Effluents and Activities and Facilities were found to be the major stressing factors to the river ecosystem. The information gained should help water managers find the most time-efficient and cost-effective measures to address river degradation.

  14. Effects of Urbanization on the Condition of Streams in the Piedmont of North Carolina: Responses of Benthic Macroinvertebrate Assemblages

    Science.gov (United States)

    Cuffney, T. F.; Harned, D. A.; McMahon, G.; Giddings, E. M.

    2004-12-01

    The effects of urbanization on the physical, chemical, and biological characteristics of streams in the North Carolina Piedmont were investigated as part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program. Over 1,200 candidate basins (2-3rd order streams) were identified using a 30-m digital elevation model. A multimetric urban intensity index (UII) derived from population, infrastructure, land use, land cover, and socioeconomic factors was used to characterize the degree of urbanization in each basin. Candidate basins were grouped together based on natural features (e.g., ecoregion, elevation, relief, and soil characteristics) and a subset of 30 basins was selected for study on the basis of uniformity in natural features, representation of the urban gradient (i.e., low to high UII), and accessibility. Biological (fish, benthic macroinvertebrates, and algae), physical (stream stage, temperature, and habitat), and chemical (nutrients, pesticides, and major ions) characteristics were measured in each stream and related to changes in the UII. Biological responses were assessed using multivariate (i.e., assemblage ordinations) and multimetric (i.e., assemblage metrics) methods. The relations between invertebrate responses, the UII, and characteristics of urbanization are described in this paper. These relations were examined using correlations and regressions. Invertebrate assemblages exhibited strong responses to the UII based on ordination site scores (Y = -0.013X + 1.613, R2 = 0.78, P urbanization. Response rates in the North Carolina Piedmont were similar to response rates reported for the Boston, MA (ordination -0.016, EPT richness -0.268, tolerance 0.015), Birmingham, AL (ordination -0.017, EPT richness -0.168, tolerance 0.015), and Salt Lake City, UT (ordination -0.012, EPT richness -0.169, tolerance 0.021) metropolitan areas based on previous NAWQA Program urban gradient studies. The characteristics of urbanization most strongly

  15. Nationwide Benthic Macroinvertebrate Assemblage Multimetric Indices: Identifying Inconsistencies and Limitations in Reporting Stream Impairment Status, USA

    Science.gov (United States)

    Lau, J. K.; Lauer, T. E.

    2015-07-01

    The objective of this study was to identify the current status of stream water-quality assessment and reporting methods for four states in the Ohio River basin (Indiana, Ohio, Tennessee, and Virginia), as required by the 305(b) section of the United States (US) Clean Water Act. Specifically, we clarified the discrepancies that exist among stream-impairment status classified by benthic macroinvertebrate multimetric indices (MMIs) and depicted using Geographic Information Systems shapefiles. In addition, we provided guidance in solving some of the comparability problems that arise when developing state-specific MMIs and depicting stream-impairment status using Geographic Information Systems technology. The MMI variation among states and differences in shapefile formats resulted in a nationwide dataset, which cannot be directly compared. Incorporating the changes suggested in this study allow for a uniform assessment and reporting method nationwide. Successful implementation of these changes would strengthen the US Environmental Protection Agency efforts to identify impaired streams and sources of those impairments without the limitations of state-by-state .developed assessment methods.

  16. Benthic macroinvertebrate assemblages and sediment toxicity testing in the Ely Creek watershed restoration project

    International Nuclear Information System (INIS)

    The Ely Creek watershed in Lee County, Virginia, contains an abundance of abandoned mined land (AML) seeps that contaminate the majority of the creek and its confluence into Big Stone Creek. Contaminated sediments had high concentrations of iron (∼10,000 mg/kg), aluminum (∼1,500 mg/kg), magnesium (∼400 mg/kg) and manganese (∼150 mg/kg). Copper and zinc generally ranged from 3 to 20 mg/kg. Benthic macroinvertebrates surveys at six of 20 sites sampled in the watershed yielded no macroinvertebrates, while eight others had total abundances of 1 to 9 organisms. Four reference sites contained ≥100 organisms and at least 14 different taxa. Laboratory, 10-day survival/impairment sediments tests with Daphnia magna did not support the field data. Mortality of 92 to 100% for D. magna occurred in samples collected from six cities. Daphnid reproduction was more sensitive than laboratory test organism survivorship; however, neither daphnid survivorship nor reproduction were good predictors of taxa richness. Laboratory test concerns included the use of a reference diluent water rather than site specific diluent water

  17. Paleoecology of Benthic Foraminifera in Coral Reefs Recorded in the Jurassic Tuwaiq Mountain Formation of the Khashm Al-Qaddiyah Area, Central Saudi Arabia

    Institute of Scientific and Technical Information of China (English)

    Mohamed Youssef; Abdelbaset S El-Sorogy

    2015-01-01

    Thirty three benthic foraminiferal species belong to 23 genera and 16 families have been recorded from the coral reefs of the Callovian Tuwaiq Formation, Khashm Al-Qaddiyah area, Central Saudi Arabia. Three species:Astacolus qaddiyahensis, Nodosaria riyadhensis, Siderolites jurassica are believed to be new. Nearly all identified foraminifera are of Atlantic-Miditeranean affinity. The fo-raminiferal assemblage recorded in the present work is mixed of open marine, moderately deep ma-rine conditions associations and shallow to deep lagoon. The reefal part of upper Twiaq Formation may have been deposited in shallow water of lower to middle shelf depth (20–50 m) as indicated by abundant corals and benthic foraminifera. The coral fauna and bearing benthic foraminifera indi-cated moderate water energy.

  18. Foraminiferal response to environmental changes in Kiel Fjord, SW Baltic Sea

    Directory of Open Access Journals (Sweden)

    J. Schönfeld

    2008-08-01

    Full Text Available The living benthic foraminiferal assemblages in Kiel Fjord (SW Baltic Sea were investigated in the years 2005 and 2006. The faunal studies were accomplished by geochemical analyses of surface sediments. In general, sediment pollution by copper, zinc, tin and lead is assessed as moderate in comparison with levels reported from other areas of the Baltic Sea. However, the inner Kiel Fjord is still exposed to a high load of metals and organic matter due to enhanced accumulation of fine-grained sediments in conjunction with potential pollution sources as shipyards, harbours and intensive traffic. The results of our survey show that the dominant environmental forcing of benthic foraminifera is nutrients availability coupled with human impact. A comparison with faunal data from the 1960s reveals apparent changes in species composition and population densities. The stress-tolerant species Ammonia beccarii invaded Kiel Fjord. Ammotium cassis had disappeared that reflects apparently the changes in salinity over the last 10 years. These changes in foraminiferal community and a significant increase of test abnormalities indicate an intensified environmental stress since the 1960s.

  19. Fluctuations of Mediterranean outflow water circulation in the Gulf of Cadiz during MIS 5 to 7: Evidence from benthic foraminiferal assemblage and stable isotope records

    Digital Repository Service at National Institute of Oceanography (India)

    Singh, A.D.; Rai, A.K.; Tiwari, M.; Naidu, P.D.; Verma, K.; Chaturvedi, M.; Niyogi, A.; Pandey, D.

    . Financial support was received from the IODP-India, National Centre for Antarctic and Ocean Research, MoES. MT thanks ISRO-GBP for support. The AMS radiocarbon dating was done at the NSF-Arizona AMS Laboratory, University of Arizona. 15    References... the Messinian salinity crisis. Nature, 462, 778-782. doi:10.1038/nature08555. Gonthier, E.G., Faugères, J.C., Stow, D.A.V., 1984. Contourite facies of the Faro Drift, Gulf of Cadiz. In: Stow, D.A.V., Piper, D.J.W. (Eds.), Fine‐ grained sediments: Deep...

  20. Between-Habitat Variation of Benthic Cover, Reef Fish Assemblage and Feeding Pressure on the Benthos at the Only Atoll in South Atlantic: Rocas Atoll, NE Brazil.

    Science.gov (United States)

    Longo, G O; Morais, R A; Martins, C D L; Mendes, T C; Aued, A W; Cândido, D V; de Oliveira, J C; Nunes, L T; Fontoura, L; Sissini, M N; Teschima, M M; Silva, M B; Ramlov, F; Gouvea, L P; Ferreira, C E L; Segal, B; Horta, P A; Floeter, S R

    2015-01-01

    The Southwestern Atlantic harbors unique and relatively understudied reef systems, including the only atoll in South Atlantic: Rocas atoll. Located 230 km off the NE Brazilian coast, Rocas is formed by coralline red algae and vermetid mollusks, and is potentially one of the most "pristine" areas in Southwestern Atlantic. We provide the first comprehensive and integrative description of the fish and benthic communities inhabiting different shallow reef habitats of Rocas. We studied two contrasting tide pool habitats: open pools, which communicate with the open ocean even during low tides, thus more exposed to wave action; and closed pools, which remain isolated during low tide and are comparatively less exposed. Reef fish assemblages, benthic cover, algal turfs and fish feeding pressure on the benthos remarkably varied between open and closed pools. The planktivore Thalassoma noronhanum was the most abundant fish species in both habitats. In terms of biomass, the lemon shark Negaprion brevirostris and the omnivore Melichtys niger were dominant in open pools, while herbivorous fishes (mainly Acanthurus spp.) prevailed in closed pools. Overall benthic cover was dominated by algal turfs, composed of articulated calcareous algae in open pools and non-calcified algae in closed pools. Feeding pressure was dominated by acanthurids and was 10-fold lower in open pools than in closed pools. Besides different wave exposure conditions, such pattern could also be related to the presence of sharks in open pools, prompting herbivorous fish to feed more in closed pools. This might indirectly affect the structure of reef fish assemblages and benthic communities. The macroalgae Digenea simplex, which is uncommon in closed pools and abundant in the reef flat, was highly preferred in herbivory assays, indicating that herbivory by fishes might be shaping this distribution pattern. The variations in benthic and reef fish communities, and feeding pressure on the benthos between open and

  1. Between-Habitat Variation of Benthic Cover, Reef Fish Assemblage and Feeding Pressure on the Benthos at the Only Atoll in South Atlantic: Rocas Atoll, NE Brazil.

    Directory of Open Access Journals (Sweden)

    G O Longo

    Full Text Available The Southwestern Atlantic harbors unique and relatively understudied reef systems, including the only atoll in South Atlantic: Rocas atoll. Located 230 km off the NE Brazilian coast, Rocas is formed by coralline red algae and vermetid mollusks, and is potentially one of the most "pristine" areas in Southwestern Atlantic. We provide the first comprehensive and integrative description of the fish and benthic communities inhabiting different shallow reef habitats of Rocas. We studied two contrasting tide pool habitats: open pools, which communicate with the open ocean even during low tides, thus more exposed to wave action; and closed pools, which remain isolated during low tide and are comparatively less exposed. Reef fish assemblages, benthic cover, algal turfs and fish feeding pressure on the benthos remarkably varied between open and closed pools. The planktivore Thalassoma noronhanum was the most abundant fish species in both habitats. In terms of biomass, the lemon shark Negaprion brevirostris and the omnivore Melichtys niger were dominant in open pools, while herbivorous fishes (mainly Acanthurus spp. prevailed in closed pools. Overall benthic cover was dominated by algal turfs, composed of articulated calcareous algae in open pools and non-calcified algae in closed pools. Feeding pressure was dominated by acanthurids and was 10-fold lower in open pools than in closed pools. Besides different wave exposure conditions, such pattern could also be related to the presence of sharks in open pools, prompting herbivorous fish to feed more in closed pools. This might indirectly affect the structure of reef fish assemblages and benthic communities. The macroalgae Digenea simplex, which is uncommon in closed pools and abundant in the reef flat, was highly preferred in herbivory assays, indicating that herbivory by fishes might be shaping this distribution pattern. The variations in benthic and reef fish communities, and feeding pressure on the benthos

  2. Response of deep-sea benthic foraminifera to Miocene paleoclimatic events, DSDP site 289

    International Nuclear Information System (INIS)

    Changes in the Miocene deep-sea benthic foraminifera at DSDP Site 289 closely correlate to the climatically induced variations in deep and bottom waters in the Pacific Ocean. In early Miocene time, oxygen and carbon isotopes indicate that bottom waters were relatively warm and poorly oxygenated. Benthic foraminiferal assemblages are characterized by various species inherited from the Oligocene. Expansion of the Antarctic icecap in the early middle Miocene, 14-16 m.y. ago, increased oxygen isotope values, produced cold, more oxygenated bottom waters and lead to a turnover in the benthic foraminifera. An Oligocene-early Miocene assemblage was replaced by a cibicidoid-dominated assemblage. Some species became extinct and benthic faunas became more bathymetrically restricted with the increased stratification of deep waters in the ocean. In mid-Miocene time, Epistominella exigua and E. umbonifera, indicative of young, oxygenated bottom waters, are relatively common at DSDP Site 289. Further glacial expansion 5-9 m.y. ago lowered sealevel, increased oceanic upwelling and associated biological productivity and intensified the oxygen minima. Abundant hispid and costate uvigerines become a dominant faunal element at shallow depths above 2500 m as E. umbonifera becomes common to abundant below 2500 m. By late Miocene time, benthic faunas similar in species composition and proportion to modern faunas on the Ontong-Java plateau, had become established. (Auth.)

  3. Living benthic foraminifera as an environmental proxy in coastal ecosystems: A case study from the Aegean Sea (Greece, NE Mediterranean)

    Science.gov (United States)

    Koukousioura, Olga; Dimiza, Margarita D.; Triantaphyllou, Maria V.; Hallock, Pamela

    2011-12-01

    The species composition of the epiphytic benthic foraminiferal fauna was compared at two coastal locations in the Aegean Sea. Samples were collected during August 2001 and July 2003 along the southeastern coast of Andros Island at Korthi Gulf, where there are minimal anthropogenic activities, and at Kastro Gulf, with substantial anthropogenic influence. This study represents the first application of the FORAM Index (FI), which is a single-metric index for water quality originally developed for western Atlantic reef foraminiferal assemblages, to Mediterranean assemblages. Multivariate analyses distinguished three clusters of sample sites representing three foraminiferal assemblages. Samples dominated by the mixotrophic species, A. lobifera, were collected primarily from sites along the northern coasts of both gulfs. Characteristics of this assemblage, including relatively high dominance (D = 0.27-0.51), lower Shannon-Wiener diversity (H' = 1.3-2.1) and high FI (6.6-8.2), all reflect oligotrophic environmental conditions typical of pristine waters of the Aegean Sea. A. lobifera was typically the most common species in the second assemblage, though relative abundances of heterotrophic taxa were higher, resulting in somewhat higher diversity (H' = 1.6-2.4) and lower dominance (D = 0.14-0.36). These indices, as well as the FI range of 3.5-7.0 indicated somewhat more prevalent organic carbon resources but still relatively high water quality. This assemblage was found along the southern coast of Korthi Gulf and at more interior sites in northern Kastro Gulf. The third assemblage was dominated by smaller heterotrophic species, including notable proportions of the stress-tolerant taxa Ammonia spp. and Elphidium spp., and had few or no A. lobifera. Diversity (H' = 1.4-2.0) and dominance (D = 0.22-0.47) indices were similar to those for the first assemblage, but FI values were much lower (2.0-3.4). Samples characterized by this assemblage were collected only from the southern

  4. Temporal trends in algae, benthic invertebrate, and fish assemblages in streams and rivers draining basins of varying land use in the south-central United States, 1993-2007

    Science.gov (United States)

    Miller, Matthew P.; Kennen, Jonathan G.; Mabe, Jeffrey A.; Mize, Scott V.

    2012-01-01

    Site-specific temporal trends in algae, benthic invertebrate, and fish assemblages were investigated in 15 streams and rivers draining basins of varying land use in the south-central United States from 1993–2007. A multivariate approach was used to identify sites with statistically significant trends in aquatic assemblages which were then tested for correlations with assemblage metrics and abiotic environmental variables (climate, water quality, streamflow, and physical habitat). Significant temporal trends in one or more of the aquatic assemblages were identified at more than half (eight of 15) of the streams in the study. Assemblage metrics and abiotic environmental variables found to be significantly correlated with aquatic assemblages differed between land use categories. For example, algal assemblages at undeveloped sites were associated with physical habitat, while algal assemblages at more anthropogenically altered sites (agricultural and urban) were associated with nutrient and streamflow metrics. In urban stream sites results indicate that streamflow metrics may act as important controls on water quality conditions, as represented by aquatic assemblage metrics. The site-specific identification of biotic trends and abiotic–biotic relations presented here will provide valuable information that can inform interpretation of continued monitoring data and the design of future studies. In addition, the subsets of abiotic variables identified as potentially important drivers of change in aquatic assemblages provide policy makers and resource managers with information that will assist in the design and implementation of monitoring programs aimed at the protection of aquatic resources.

  5. Ensamble de crustáceos bentónicos en un lago salino tropical Benthic crustaceans assemblage in a tropical, saline lake

    Directory of Open Access Journals (Sweden)

    Ma. del Carmen Hernández

    2010-10-01

    Full Text Available El presente trabajo reconoce la composición, estructura y distribución espacial del ensamble de crustáceos bentónicos de Alchichica, un lago salino tropical ubicado en el extremo oriental del altiplano mexicano. El lago presenta una riqueza taxonómica de crustáceos bentónicos compuesta por 1 anfípodo (Hyalella azteca, 1 isópodo (Caecidotea williamsi y 2 ostrácodos (Limnocythere inopinata y Candona sp.. Comparada con otros lagos tropicales, la riqueza de especies es reducida. A pesar de lo anterior, es importante mencionar el grado elevado de endemismo representado por C. williamsi, recientemente descrita para el lago Alchichica; adicionalmente, es factible que tanto Candona como H. azteca sean especies nuevas y endémicas del lago. Los crustáceos bentónicos se distribuyen desde la zona litoral hasta la zona más profunda del lago (62 m con abundancias y riqueza taxonómica variables. Los ostrácodos fueron los crustáceos que con mayor frecuencia se recolectaron en el lago, en la zona litoral, en el talud, y en la zona profunda de la que son habitantes exclusivos. Los anfípodos constituyeron el segundo grupo en abundancia de la zona litoral y talud y estuvieron ausentes en la zona profunda. Los isópodos sólo se encuentran asociados a los depósitos de tufa, hábitat característico del lago que se extiende a lo largo del talud, por lo que con las técnicas de muestreo tradicional empleadas en el presente estudio no fueron capturados. En este ensamble de crustáceos predominan las especies de desarrollo directo y con posiciones tróficas que incluyen componentes herbívoros (H. azteca, omnívoros (C. williamsi y bacterívoros (L. inopinata y Candona sp..This work acknowledges the composition, structure and spatial distribution of the benthic crustaceans assemblage of Alchichica, a tropical saline lake located in the easternmost portion of the Mexican highlands. The benthic crustaceans' assemblage was comprised by 1 amphipod

  6. Abiotic stream types and species assemblages: is there any simle linkage? Czech streams and benthic macroinvertebrates as an example

    Czech Academy of Sciences Publication Activity Database

    Zahrádková, S.; Brabec, K.; Kokeš, J.; Němejcová, D.; Soldán, Tomáš; Jarkovský, J.; Pařil, P.; Hájek, O.

    2005-01-01

    Roč. 29, - (2005), s. 1087-1094 R&D Projects: GA AV ČR(CZ) 1QS500070505 Institutional research plan: CEZ:AV0Z50070508 Keywords : typology * biocenoses * benthic macroinvertebrates Subject RIV: EH - Ecology, Behaviour

  7. Ancient fish and recent invaders: white sturgeon Acipenser transmontanus diet response to invasive-species-mediated changes in a benthic prey assemblage

    Science.gov (United States)

    Zeug, Steven C; Brodsky, Annie; Kogut, Nina; Stewart, Robin; Merz, Joe

    2014-01-01

    Invasive organisms can have significant impacts on native species, and the San Francisco Estuary (SFE), California, USA, is one of the world's most invaded estuaries. Decline of native white sturgeon Acipenser transmontanus abundance in the SFE has been acknowledged, but underlying mechanisms are poorly understood. Invasion by the overbite clam Potamocorbula amurensis has drastically altered the SFE benthic prey community, yet little is known about how this change has affected sturgeon diets. We investigated changes in the diet of white sturgeon following the overbite clam invasion and subsequent shift in the SFE benthic prey assemblage. Gut content analysis was used to compare white sturgeon prey composition and importance between the pre- and post-invasion periods. Additionally, stable isotope analysis was employed to estimate the assimilation of prey items to sturgeon biomass. Overbite clams dominated diets in the post-invasion period, accounting for 82 to 93% of total volume. Stable isotope analysis confirmed the importance of this prey item, although their assimilated contribution to sturgeon biomass was estimated to be less (70 to 83%) than gut contents indicated. The frequency of fish in white sturgeon guts increased in the post-invasion period, and isotope analysis indicated relatively large contributions of fish to sturgeon biomass (3.7 to 19%). The trophic adaptability of white sturgeon has allowed them to exploit this new prey source (overbite clam). Future conservation and restoration efforts must consider a potentially destabilized food web given the large importance of a single prey item.

  8. Benthic foraminifera and trace element distribution: a case-study from the heavily polluted lagoon of Venice (Italy).

    Science.gov (United States)

    Coccioni, Rodolfo; Frontalini, Fabrizio; Marsili, Andrea; Mana, Davide

    2009-01-01

    Living benthic foraminiferal assemblages were studied in surface samples collected from the lagoon of Venice (Italy) in order to investigate the relationship between these sensitive microorganisms and trace element pollution. Geochemical analysis of sediments shows that the lagoon is affected by trace element pollution (Cd, Cu, Ni, Pb, Zn and Hg) with the highest concentrations in its inner part, which corresponds to the Porto Marghera industrial area. The biocenosis are largely dominated by Ammonia tepida, Haynesina germanica and Cribroelphidium oceanensis and, subordinately, by Aubignyna perlucida, Ammonia parkinsoniana and Bolivina striatula. Biotic and abiotic factors were statistically analyzed with multivariate technique of cluster analysis and principal component analysis. The statistical analysis reveals a strong relationship between trace elements (in particular Mn, Pb and Hg) and the occurrence of abnormalities in foraminiferal tests. Remarkably, greater proportions of abnormal specimens are usually found at stations located close to the heaviest polluted industrial zone of Porto Marghera. This paper shows that benthic foraminifera can be used as useful and relatively speedy and inexpensive bio-indicators in monitoring the health quality of the lagoon of Venice. It also provides a basis for future investigations aimed at unraveling the benthic foraminiferal response to human-induced pollution in marine and transitional marine environments. PMID:19733368

  9. THE RESPONSE OF BENTHIC MACROINVERTEBRATE AND FISH ASSEMBLAGES TO HUMAN IMPACT ALONG THE LOWER STRETCH OF THE RIVERS MORAVA AND DYJE (DANUBE RIVER BASIN, CZECH REPUBLIC

    Directory of Open Access Journals (Sweden)

    Zdeněk Adámek

    2013-10-01

    Full Text Available The lower Morava and Dyje rivers belong among the large lowland rivers on the southeast of the Czech Republic flowing into the Danube 69 km downstream of their confluence. Despite their high nature value and environment protection, both rivers suffered from heavy pollution from the sixties to the eighties of the last century. Significant improvement of their water quality during the last two decades resulted in the partial recovery of former assemblages of both benthic macroinvertebrates and fish. Recently, altogether 262 and 137 taxa of macrozoobenthos were recorded at the Dyje and Morava rivers, respectively. In the River Dyje, 3 and 21 non-native and threatened (according to IUCN categories invertebrate species, respectively, were ascertained, whilst in the River Morava their numbers were 2 and 10, respectively. The fish assemblage consisted of 23 and 24 species, respectively, plus one hybrid in each of the rivers, bleak being by far the most abundant fish. In the sections under study, several rare and/or protected species were also recorded. Two of them, ide (Leuciscus idus and burbot (Lota lota belong among vulnerable fish species and four others, white-eye bream (Abramis sapa, striped ruffe (Gymnocephalus schraetser, streber (Zingel streber and zingel (Zingel zingel, are considered as critically endangered species. Currently, both lower stretches of the rivers Morava and Dyje have been heavily invaded by round goby, Neogobius melanostomus.

  10. The health of benthic diatom assemblages in lower stretch of a lesser Himalayan glacier-fed river, Mandakini

    Indian Academy of Sciences (India)

    Prakash Nautiyal; Asheesh Shivam Mishra; Jyoti Verma

    2015-03-01

    This study examines the ecological state of epilithic diatom assemblages along the lower stretch of Mandakini, a glacier-fed Himalayan river. The diatoms were sampled at four stations during winter and summer, only once in each season. Valve counts were obtained from Naphrax mounts prepared from each sample. Assemblages were recorded for each location. The software OMNIDIA Ver. 5.3 was used for computing the ecological values from the sample counts. Normally Achnanthidium spp. dominated the assemblages, except Nitzschia fonticola (Grunow) at S1 (Kund) and Encyonema minutum (Hilse in Rabh) at S4 (Rudraprayag), only during summer. The ecological values revealed that the assemblages were in -mesosaprobic and mésotraphentic states. However, at S4, trophic state was observed to be eutraphentic. Louis Leclercq index indicated that organic pollution was nonexistent, while the anthropogenic eutrophication was low except at S2 (Tilwara) and S3 (Medanpur) in summer and was moderate at S4 in winter characterized by a lean flow. The most abundant indicator taxa for anthropogenic eutrophication are varied; Cymbella tumida (Brebisson-Van Heurck) at S1, Encyonema minutum at S2, S4 while Surirella aungusta (Kutzing) at S3. Ordination showed that the taxa indicating degradation and anthropogenic eutrophication figured as characteristic taxa at respective locations.

  11. Spatial and temporal benthic species assemblage responses with a deployed marine tidal energy device: a small scaled study.

    Science.gov (United States)

    Broadhurst, Melanie; Orme, C David L

    2014-08-01

    The addition of man-made structures to the marine environment is known to increase the physical complexity of the seafloor, which can influence benthic species community patterns and habitat structure. However, knowledge of how deployed tidal energy device structures influence benthic communities is currently lacking. Here we examined species biodiversity, composition and habitat type surrounding a tidal energy device within the European Marine Energy Centre test site, Orkney. Commercial fishing and towed video camera techniques were used over three temporal periods, from 2009 to 2010. Our results showed increased species biodiversity and compositional differences within the device site, compared to a control site. Both sites largely comprised of crustacean species, omnivore or predatory feeding regimes and marine tide-swept EUNIS habitat types, which varied over the time. We conclude that the device could act as a localised artificial reef structure, but that further in-depth investigations are required. PMID:24840255

  12. Biogenic reefs affect multiple components of intertidal soft-bottom benthic assemblages: the Lanice conchilega case study

    Science.gov (United States)

    De Smet, Bart; D'Hondt, An-Sofie; Verhelst, Pieterjan; Fournier, Jérôme; Godet, Laurent; Desroy, Nicolas; Rabaut, Marijn; Vincx, Magda; Vanaverbeke, Jan

    2015-01-01

    Biogenic reefs composed of the tube-building polychaete Lanice conchilega are important from a conservation point of view because they noticeably increase the biodiversity in otherwise species poor environments. However, up to now, little or no attention has been paid to the intertidal epi- and hyperbenthic communities associated with the reefs. Therefore, this is the first study which focuses on the effect of L. conchilega reefs on the entire bentho-pelagic community at two different locations. Environmental variables were measured and macro-, epi- and hyperbenthic communities were sampled within a L. conchilega reef and a control area at two locations in France: the bay of the Mont Saint-Michel (BMSM) and Boulogne-sur-Mer (Boulogne). The effect of the reef presence on the benthic community was studied with a 3-factor (Reef, Location and Period) Permanova. In addition, the relationship between the benthic community and the environmental variables was investigated using Distance-based linear models (DistLM). Most collected organisms were sampled in the reef area (macrobenthos: 91%, epibenthos: 81% and hyperbenthos: 78.5%) indicating that, independent of the location, the L. conchilega reefs positively affect all three associated benthic communities. However, the extent of the effect seems to be most pronounced for the macrobenthos and less distinct in case of the hyperbenthos. The macro-, and epibenthos are mainly structured by biotic variables (L. conchilega density and macrobenthic food availability respectively), while the hyperbenthos is rather structured by environmental variables. In general, L. conchilega reefs do not only affect abundances and diversity but they substantially steer the structure of the intertidal benthic sandy beach ecosystem.

  13. The intriguing relationship between coiling direction and reproductive mode in benthic foraminifera

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Rao, A

    direction changes. The relationship between mode of reproduction and coiling directions in benthic foraminifera is explored. Benthic foraminiferal species Cavarotalia annectens (Paarker & Jones) in 58 samples obtained from a core off Karwar, west coast...

  14. Effects of urbanization on benthic macroinvertebrate assemblages in contrasting environmental settings: Boston, Massachusetts; Birmingham, Alabama; and Salt Lake City, Utah

    Science.gov (United States)

    Cuffney, T.F.; Zappia, H.; Giddings, E.M.P.; Coles, J.F.

    2005-01-01

    Responses of invertebrate assemblages along gradients of urban intensity were examined in three metropolitan areas with contrasting climates and topography (Boston, Massachusetts; Birmingham, Alabama; Salt Lake City, Utah). Urban gradients were defined using an urban intensity index (UII) derived from basin-scale population, infrastructure, land-use, land-cover, and socioeconomic characteristics. Responses based on assemblage metrics, indices of biotic integrity (B-IBI), and ordinations were readily detected in all three urban areas and many responses could be accurately predicted simply using regional UIIs. Responses to UII were linear and did not indicate any initial resistance to urbanization. Richness metrics were better indicators of urbanization than were density metrics. Metrics that were good indicators were specific to each study except for a richness-based tolerance metric (TOLr) and one B-IBI. Tolerances to urbanization were derived for 205 taxa. These tolerances differed among studies and with published tolerance values, but provided similar characterizations of site conditions. Basin-scale land-use changes were the most important variables for explaining invertebrate responses to urbanization. Some chemical and instream physical habitat variables were important in individual studies, but not among studies. Optimizing the study design to detect basin-scale effects may have reduced the ability to detect local-scale effects. ?? 2005 by the American Fisheries Society.

  15. 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

    Aquatic ecosystems of highland rivers are different from those of low altitude rivers because of the specific topography and environmental parameters associated with high altitudes. Yalutsangpo, the upper course of the Brahmaputra River, is the highest major river in the world, flowing from west to east across Tibet, China and pouring into India. Macroinvertebrates were sampled from Yalutsangpo and its tributaries, the Lhasa, Niyang, and Parlong Tsangpo Rivers, from October 2009 to June 2010, to study characters of the highland aquatic ecosystem. Altogether, 110 macroinvertebrate taxa belonging to 57 families and 102 genera were identified from the basin. The biodiversity and composition of macroinvertebrate assemblages were strongly affected by altitude gradients. Local diversity represented by taxa richness and the improved Shannon-Wiener index were high at altitudes of 3,300-3,700 m, among which suitability of habitat was higher due to the better integrated environmental conditions of water temperature, dissolved oxygen, and aquatic vegetation, etc. Macroinvertebrates were grouped into shredders, scrapers, predators, collector-filterers, and collector-gatherers according to their feeding behaviors. It was found that the distributions of the functional feeding groups varied with habitat altitudes. Shredders were present at altitudes of 2,900-4,400 m, while scrapers mainly inhabited altitudes of 3,500-4,500 m, and collector-filterers preferred 3,500-4,000 m. Even though the local taxa richness was not high at each site, the taxonomic composition and density of the assemblages varied greatly among the different sites, resulting in much higher regional diversity compared to the lowland river with similar flow and substrate conditions. The regional cumulative taxa richness of Yalutsangpo decreased and more families were lost as the altitude increased. However, some families that were newly present as the altitude increased were essential for sustaining the high

  16. The benthic marine assemblages of the estuarine and shallow marine Upper Burdigalian deposits of the Korneuburg Basin in Lower Austria

    Science.gov (United States)

    Hengst, Babette; Zuschin, Martin; Harzhauser, Mathias; Mandic, Oleg; Roetzel, Reinhard

    2010-05-01

    In the course of highway constructions (Wiener Außenring-Schnellstraße (S1)) a detailed sedimentological transect of 1.8 km length was logged in deposits of the Central Paratethys near the village of Stetten, N of Korneuburg in Lower Austria. A total of 324 sediment- and 118 molluscan samples was studied. The siliciclastic succession consists of pelitic and sandy sediments and sandstones and is rich in fossils. The fossil remains consist of sponges, corals, serpulids, molluscs, balanids, echinoderms, fish and micromammals. Quantitatively the molluscs dominate and have been studied in detail. 139 species were determined from more than 11,000 shells. Two gastropod species, Agapilia pachii und Granulolabium bicinctum make up more than 53% of the assemblage. Another 11 species (Nassarius edlaueri, Bittium spina, Loripes dujardini, Hydrobia spp., Paphia subcarinata, Cyllenina ternodosa, Turritella gradata, Corbula gibba, Cerastoderma praeplicata, Striarca lactea, Sandbergeria perpusilla) each contributes more than 1% to the total molluscan composition, but all other 126 species are quantitatively unimportant. A conspicuous alternation between intertidal and shallow subtidal mollusc associations is evident. The intertidal is dominated by the superabundant Agapilia pachii and Granulolabium plicatum, whereas the heavily bioturbated fully marine subtidal is characterized by a more diverse assemblage including Turritella gradata, Nassarius edlaueri, Anadara diluvii and various venerids. Additionally, layers with large fragments of Crassostrea and thin coal deposits with Terebralia bidentata are quite abundant in the section. Washed in land snails (e.g., Planorbidae) and river snails (Melanopsidae) occur occasionally. This faunal composition, along with its typical alternation points to a vivid dynamic within this Lower Miocene, subtropical ecosystem in the paleo-estuary of the southern Korneuburg basin.

  17. Environmental changes during the Paleocene–Eocene Thermal Maximum in Spitsbergen as reflected by benthic foraminifera

    Directory of Open Access Journals (Sweden)

    Jenö Nagy

    2013-07-01

    Full Text Available The study deals with environmental changes during the Paleocene–Eocene Thermal Maximum (PETM and its background conditions in Spitsbergen through analysis of benthic foraminiferal assemblages (FA in a section drilled in the Paleogene Central Basin. The impact of this extreme global warming occurs here in prodelta shelf mudstones composing the lower part of the Gilsonryggen Member (Frysjaodden Formation. The start of the PETM perturbation is marked by a faunal turnover, in which the medium-diversity circumpolar Reticulophragmium assemblage was replaced by a low-diversity Trochammina fauna. During the hyperthermal period, benthic foraminiferal diversity decreased severely, while the dominance of small-sized taxa with epifaunal morphology strongly increased. This low-diversity fauna occurs in sediments with a reduced thorium/uranium ratio (proxy for oxygenation and kaolinite enrichment (proxy for high humidity. The faunal changes were thus caused by the combined effects of hypoxic and hyposaline conditions in a stratified water column, due to extreme warming with its accompanying intensified hydrologic cycle. The PETM acme coincides with the maximum flooding surface (MFS of the Gilsonryggen depositional sequence, composed of the Gilsonryggen Member and the overlying Battfjellet and Aspelintoppen formations. The transgressive phase of the sequence was initiated by local tectonics, while the eustatic sea-level rise of the PETM was superimposed on this transgression.To access the supplementary material for this article, please see supplementary files under Article Tools online.

  18. Cold seep and oxygen minimum zone associated sources of margin heterogeneity affect benthic assemblages, diversity and nutrition at the Cascadian margin (NE Pacific Ocean)

    Science.gov (United States)

    Guilini, Katja; Levin, Lisa A.; Vanreusel, Ann

    2012-04-01

    Hydrate Ridge (HR), located on the northeastern Pacific margin off Oregon, is characterized by the presence of outcropping hydrates and active methane seepage. Additionally, permanent low oxygen conditions overlay the benthic realm. This study evaluated the relative influence of both seepage and oxygen minima as sources of habitat heterogeneity and potential stress-inducing features on the bathyal metazoan benthos (primarily nematodes) at three different seep and non-seep HR locations, exposed to decreasing bottom-water oxygen concentrations with increasing water depth. The nematode seep communities at HR exhibited low diversity with dominance of only one or two genera (Daptonema and Metadesmolaimus), elevated average individual biomass and δ13C evidence for strong dependance on chemosynthesis-derived carbon, resembling deep-sea seeps worldwide. Although the HR seep habitats harbored a distinct nematode community like in other known seep communities, they differed from deep-sea seeps in well-oxygenated waters based on that they shared the dominant genera with the surrounding non-seep sediments overlain by oxygen-deficient bottom water. The homogenizing effect of the oxygen minimum zone on the seep nematode assemblages and surrounding sediments was constant with increasing water depth and concomitant greater oxygen-deficiency, resulting in a loss of habitat heterogeneity.

  19. Environmental impact of bleufin tuna aquaculture on benthic assemblages in the western coast of Baja California, Mexico

    Science.gov (United States)

    Diaz-Castaneda, V.

    2013-05-01

    Sea-cage farming results in a constant rain of organic waste onto the surrounding benthos. In Baja California there is growing concern over the effects of sea-cages on the local environment: sediment chemistry and benthic communities. Samples were taken in 18 stations using a Van veen grab (0.1 m2) in Bahía Salsipuedes, Baja California in 2003, 2004, 2006 and 2008. Organisms belonging to 7 Phyla were collected: Polychaeta, Mollusca, Crustacea, Echinodermata, Cnidaria, Sipuncula and Bryozoa. Polychaetes were the dominant group followed by crustaceans and mollusks. Polychaetes were represented by 37 families and 157 species. Best represented families were Paraonidae, Cirratulidae, Spionidae, Glyceridae and Maldanidae. This study shows that in the NW area of the bay organic carbon (2.54%) and organic nitrogen (0.95%) are being accumulated (higher concentrations and lower Eh values) and smaller opportunistic species are increasing rapidly near the tuna pens. It is crucial to maintain "healthy" macrofaunal populations in order to enhance decomposition of organic matter and to prevent its excessive accumulation. The most abundant polychaete species were Aphelochaeta multifinis, Mediomastus ambiseta, Prionospio steenstrupi Spiophanes bombyx, Apoprionospio pygnaea, Paraonella sp, Monticellina sp, Aricidea (Allia) ramosa, Spiophanes bombyx and Levinsenia gracilis. The dominant trophic groups were deposit-feeders and carnivores. The buildup of organic matter on the seafloor has attracted scavenger species particularly peracarid crustaceans. Non-metric multidimensional scaling (MDS) separated stations depending of the distance to the tuna pens.

  20. An overview of the planktonic foraminiferal fauna in waters off the Kerala Coast, south-west India during summer

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, K.K.; Jayalakshmy, K.V.

    that it increases from south to north. Two distinct foraminiferal assemblages have been noted in the fauna: first is the summer tropical one typified by species such as Globigerinella aequilateralis, Globigerinoides conglobatus, G. ruber and G. sacculifer, while...

  1. Plio-Pleistocene planktonic foraminiferal biostratigraphy, paleo-oceanography, and sediment accumulation rates, northeastern Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.E.; Johnson, G.W.; Spotz, B.

    1987-05-01

    The planktonic foraminiferal biostratigraphy has been analyzed for Ocean Drilling Program's hole 625B (Leg 100), drilled to a total subbottom depth of 235 m south of De Soto Canyon in the northeast Gulf of Mexico. The hole penetrated to at least early Pliocene (zone N19), as indicated by the Globigerina nepenthes LAD (approx. 3.7 Ma) at 182 m. Preliminary seismic section of the Plio-Pleistocene sediments of the continental slope in the northeast Gulf suggested a relatively continuous depositional record. However, sediment accumulation rates have fluctuated in parallel with paleo-oceanographic changes. Percent coarse (approx. 63 ..mu..m) carbonate fraction (mainly planktonic foraminiferal tests) in hole 625 B shows high-frequency, low-amplitude fluctuations from the Pliocene to the Jaramillo paleomagnetic event (approx. 900,000 y.B.P.), whereupon low-frequency, high-amplitude fluctuations occur to the Holocene. Low-frequency, high-amplitude fluctuations correspond primarily to increased amplitude of sea level fluctuations and terrigenous dilution during low sea level stands. Percent abundance of Globorotalia menardii and percent coarse carbonate fraction in the uppermost 18 m reflects oxygen isotope stages 1-5 and therefore, primarily, ice volume and, secondarily, water temperature. However, the lack of a strict correspondence between G. menardii abundance, percent coarse carbonate fraction, and planktonic-benthic ratios (presumed dissolution indicator) lower in the hole indicates that G. menardii abundance peaks reflect not only eustatic sea level changes and water temperature but possibly also productivity (upwelling) and/or differential dissolution. Preliminary results of factor analysis of foraminiferal assemblages are also presented.

  2. Effects of hypoxia caused by mussel farming on benthic foraminifera in semi-closed Gamak Bay, South Korea.

    Science.gov (United States)

    Lee, Yeon Gyu; Jeong, Da Un; Lee, Jung Sick; Choi, Yang Ho; Lee, Moon Ok

    2016-08-15

    Seawater monitoring and geochemical and benthic foraminiferal analysis of sediments were conducted to identify the effects of hypoxia created by a mussel farm on benthic foraminifera in a semi-closed bay. Extremely polluted reductive conditions with a high content of organic matter (OM) at >12.0% and oxygen minimum zones (OMZs) with dissolved oxygen (DO) <0.4mg∙L(-1) were formed below the mussel farm in the northwest area of Gamak Bay, and gradually diffused toward the south. Highly similar patterns of variation were observed in species diversity, abundance frequency, and benthic foraminiferal assemblage distributed from Elphidium subarcticum-Ammonia beccarii in the northwest area through E. subarcticum-A. beccarii-Trochammina hadai, E. subarcticum-A. beccarii-Elphidiumclavatum, and E. clavatum-Ammonia ketienziensis in the southern area. These phenomena were caused by hydrodynamics in the current water mass. It was thought that E. subarcticum is a bioindicator of organic pollution caused by the mussel farm. PMID:27267115

  3. Benthic foraminifera as indicators of habitat change in anthropogenically impacted coastal wetlands of the Ebro Delta (NE Iberian Peninsula).

    Science.gov (United States)

    Benito, Xavier; Trobajo, Rosa; Ibáñez, Carles; Cearreta, Alejandro; Brunet, Manola

    2015-12-15

    Present-day habitats of the Ebro Delta, NE Iberian Peninsula, have been ecologically altered as a consequence of intensive human impacts in the last two centuries (especially rice farming). Benthic foraminiferal palaeoassemblages and sediment characteristics of five short cores were used to reconstruct past wetland habitats, through application of multivariate DCA and CONISS techniques, and dissimilarity coefficients (SCD). The timing of environmental changes was compared to known natural and anthropogenic events in order to identify their possible relationships. In deltaic wetlands under altered hydrological conditions, we found a decrease in species diversity and calcareous-dominated assemblages, and a significant positive correlation between microfaunal changes and organic matter content. Modern analogues supported palaeoenvironmental interpretation of the recent evolution of the Delta wetlands. This research provides the first recent reconstruction of change in the Ebro Delta wetlands, and also illustrates the importance of benthic foraminifera for biomonitoring present and future conditions in Mediterranean deltas. PMID:26563545

  4. Environmental Quality Assessment of Bizerte Lagoon (Tunisia Using Living Foraminifera Assemblages and a Multiproxy Approach.

    Directory of Open Access Journals (Sweden)

    Maria Virgínia Alves Martins

    Full Text Available This study investigated the environmental quality of the Bizerte Lagoon (Tunisia through an integrated approach that combined environmental, biogeochemical, and living benthic foraminiferal analyses. Specifically, we analyzed the physicochemical parameters of the water and sediment. The textural, mineralogical, and geochemical characteristics of the sediment, including total organic carbon, total nitrogen, simultaneously extracted metals (SEM, acid volatile sulfides (AVS, chlorophyll a, CaCO3, and changes in bacterial populations and carbon isotopes were measured. The SEM/AVS values indicated the presence of relatively high concentrations of toxic metals in only some areas. Foraminiferal assemblages were dominated by species such as A. parkinsoniana (20-91%, Bolivina striatula (<40%, Hopkinsina atlantica (<17%, and Bolivina ordinaria (<15% that cannot be considered typical of impacted coastal lagoons both in Mediterranean and northeast Atlantic regions. The results of this work suggest that Bizerte Lagoon is a unique setting. This lagoon is populated by typical marine species that invaded this ecosystem, attracted not only by the prevailing favorable environmental conditions but also by the abundance and quality of food. The results indicate that the metal pollution found in some areas have a negative impact on the assemblages of foraminifera. At present, however, this negative impact is not highly alarming.

  5. Environmental Quality Assessment of Bizerte Lagoon (Tunisia) Using Living Foraminifera Assemblages and a Multiproxy Approach

    Science.gov (United States)

    Alves Martins, Maria Virgínia; Zaaboub, Noureddine; Aleya, Lotfi; Frontalini, Fabrizio; Pereira, Egberto; Miranda, Paulo; Mane, Miguel; Rocha, Fernando; Laut, Lazaro; El Bour, Monia

    2015-01-01

    This study investigated the environmental quality of the Bizerte Lagoon (Tunisia) through an integrated approach that combined environmental, biogeochemical, and living benthic foraminiferal analyses. Specifically, we analyzed the physicochemical parameters of the water and sediment. The textural, mineralogical, and geochemical characteristics of the sediment, including total organic carbon, total nitrogen, simultaneously extracted metals (SEM), acid volatile sulfides (AVS), chlorophyll a, CaCO3, and changes in bacterial populations and carbon isotopes were measured. The SEM/AVS values indicated the presence of relatively high concentrations of toxic metals in only some areas. Foraminiferal assemblages were dominated by species such as A. parkinsoniana (20–91%), Bolivina striatula (<40%), Hopkinsina atlantica (<17%), and Bolivina ordinaria (<15%) that cannot be considered typical of impacted coastal lagoons both in Mediterranean and northeast Atlantic regions. The results of this work suggest that Bizerte Lagoon is a unique setting. This lagoon is populated by typical marine species that invaded this ecosystem, attracted not only by the prevailing favorable environmental conditions but also by the abundance and quality of food. The results indicate that the metal pollution found in some areas have a negative impact on the assemblages of foraminifera. At present, however, this negative impact is not highly alarming. PMID:26372655

  6. Assessment of impact of geochemical and environmental properties on the meiofauna (benthic foraminifer, ostracod, mollusc) assemblages: A case study in The Late Quaternary Sediments In The Gulf Of Izmir (Eastern Aegean Sea)

    Science.gov (United States)

    Yümün, Zeki Ü.

    2016-04-01

    The drilling samples collected from varying depths at 1.00-13.00 m at four different localities of Karsiyaka, Bayrakli, Inciralti and Urla (Çesmealti) in the Gulf of Izmir were studied for their geochemical, sedimantological and micropaleontological properties. The purpose of this study is to describe the meiofauna of the sediments, to determine the pollution history of the gulf and to show the effect of the pollution on the foraminifera and ostracoda. Examination of the loose sediments reveals that the gulf has been affected by the sea for a long time, and it had a rich microfaunal assemblages. Both foraminiferal tests and ostracod carapaces have coloring, and morphological abnormalities have been determined in foraminiferal tests. Peneroplis pertusus (Forskal) and P. planatus (Fichtel and Moll) have blue and black colored tests, while morphological abnormalities were observed on the tests of Ammonia compacta Hofker, Elphidium complanatum (d'Orbigny), E. crispum (Linné), E. macellum (Fichtel and Moll). The ostracod carapaces are generally gray-black colored. Heavy metal (Cr, Mn, Zn, Co, Ni, Cu) analyses have been carried out on the sediments of the Gulf of Izmir. Heavy metal concentrations are high in Bayrakli, and low in Urla (Çesmealti). Cr, Mn and Zn values are the highest in Bayrakli, whereas Co, Ni and Cu values are the highest in Inciralti. Scanning Electron Microscope (SEM) analyses were performed and no heavy metal was detected on the white and colored ostracod carapaces. When the white and colored ostracod carapaces are compared, the coloured ostracode carapace has higher Mg content, and also includes Fe, Al, N, Cl and K. Based on the results obtained, it is observed that the Bayrakli region have been more affected by the pollution than Urla (Çesmealti).

  7. Living deep-sea benthic foraminifera from the Cap de Creus Canyon (western Mediterranean): Faunal-geochemical interactions

    Science.gov (United States)

    Contreras-Rosales, L. A.; Koho, K. A.; Duijnstee, I. A. P.; de Stigter, H. C.; García, R.; Koning, E.; Epping, E.

    2012-06-01

    Rose-Bengal-stained benthic foraminifera were sampled along a depth transect from the Cap de Creus Canyon and the adjacent slope. Well-stained individuals were studied in the top 5 cm of sediment and the faunal abundances and assemblages were compared against pore-water geochemistry and biochemical composition of the sediment. Total standing stocks (TSS) of foraminifera were positively correlated with the chloroplastic pigment equivalents inventory (CPEinv; here interpreted as food quantity) and the ratio of chlorophyll-a and phaeopigment inventories (Chl-ainv/Phaeoinv; here interpreted as food quality), suggesting food quality as well as quantity play an important role in structuring the foraminiferal community. Food quality and food quantity were also identified by detrended correspondence analyses (DCA) as being the most important environmental parameters shaping the foraminiferal community structure (abundance and faunal composition). In addition, sediment redox chemistry (based here on pore-water nitrate) played an important role in controlling the foraminiferal diversity (H‧) as a negative correlation was seen between this parameter and pore-water nitrate penetration depth (NPD). No conclusive evidence of intense physical disturbance on the benthic canyon community was observed, although it could be anticipated in the area due to shelf-water downwelling (SWD) and dense shelf-water cascading (DSWC). However, foraminiferal faunas living in the canyon head and upper canyon environments may profit from the higher organic-matter availability, which is likely to be related to SWD and DSWC. The similarity between the deeper canyon and slope faunas suggests that sediment characteristics and the associated organic-matter transported by SWC and DSWC do not have a permanent effect at these depths.

  8. A decline in benthic foraminifera following the deepwater horizon event in the northeastern Gulf of Mexico.

    Directory of Open Access Journals (Sweden)

    Patrick T Schwing

    Full Text Available Sediment cores were collected from three sites (1000-1200 m water depth in the northeastern Gulf of Mexico from December 2010 to June 2011 to assess changes in benthic foraminiferal density related to the Deepwater Horizon (DWH event (April-July 2010, 1500 m water depth. Short-lived radioisotope geochronologies (²¹⁰Pb, ²³⁴Th, organic geochemical assessments, and redox metal concentrations were determined to relate changes in sediment accumulation rate, contamination, and redox conditions with benthic foraminiferal density. Cores collected in December 2010 indicated a decline in density (80-93%. This decline was characterized by a decrease in benthic foraminiferal density and benthic foraminiferal accumulation rate (BFAR in the surface 10 mm relative to the down-core mean in all benthic foraminifera, including the dominant genera (Bulimina spp., Uvigerina spp., and Cibicidoides spp.. Cores collected in February 2011 documented a site-specific response. There was evidence of a recovery in the benthic foraminiferal density and BFAR at the site closest to the wellhead (45 NM, NE. However, the site farther afield (60 NM, NE recorded a continued decline in benthic foraminiferal density and BFAR down to near-zero values. This decline in benthic foraminiferal density occurred simultaneously with abrupt increases in sedimentary accumulation rates, polycyclic aromatic hydrocarbon (PAH concentrations, and changes in redox conditions. Persistent reducing conditions (as many as 10 months after the event in the surface of these core records were a possible cause of the decline. Another possible cause was the increase (2-3 times background in PAH's, which are known to cause benthic foraminifera mortality and inhibit reproduction. Records of benthic foraminiferal density coupled with short-lived radionuclide geochronology and organic geochemistry were effective in quantifying the benthic response and will continue to be a valuable tool in determining

  9. Foraminiferal Biostratigraphy and Depositional Environment of Oloibiri-1 Well, Eastern Niger Delta, Nigeria

    OpenAIRE

    Jacinta N. Chukwu; Edward A. Okosun; Yahaya B. Alkali

    2012-01-01

    Foraminiferal biostratigraphy has been undertaken from the ditch cutting samples of Oloibiri-1 well located in the eastern Niger Delta. Oloibiri-1 well is composed of shale and mudstone/siltstone with intervals of sand/sandstone. Oloibiri-1 well which contains both planktic and benthic foraminifera, penetrated strata of Miocene age, and have been subdivided into biostratigraphic zones. The planktic zone established for the well is Praeorbulina glomerosa Zone. The benthic zone established is a...

  10. Foraminiferal species responses to in situ experimentally induced anoxia in the Adriatic Sea

    Directory of Open Access Journals (Sweden)

    D. Langlet

    2013-07-01

    Full Text Available Anoxia was successfully induced in four benthic chambers installed at 24 m depth in the northern Adriatic Sea, for periods varying from 9 days to 10 months. During the 10 months period, species richness significantly decreased. Although no significant change in Shannon diversity and Evenness is observed, the composition of the foraminiferal assemblages changes with time. This change is due to interspecific differences in tolerance with respect to anoxia and free sulphides. Leptohalysis scottii, Textularia agglutinans and Quinqueloculina cf. stelligera all showed a significant decrease with time, strongly suggesting they are sensitive to the anoxia and sulphides. Conversely, Eggerella scabra, Bulimina marginata, Lagenammina atlantica, Hopkinsina pacifica and Bolivina pseudoplicata appear to be resistant to the experimental conditions. Quinqueloculina seminula also appears to be sensitive to anoxia but shows a clear standing stock increase during the first month of the experiment, which we interpret as an opportunistic response to increasing organic matter availability due to the degradation of the dead macrofaunal organisms. It appears that none of the anoxia sensitive species is capable to accumulate intracellular nitrates. Such a capacity could be shown for some tested specimens of the dominant anoxia tolerant species E. scabra and B. marginata. However, tests on the denitrification capacity of these taxa yielded negative results, suggesting that their resistance to long-term anoxia is not due to a capacity to denitrify.

  11. Effect of disjunct size distributions on foraminiferal species abundance determinations

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.E.; Liddell, W.D.

    1988-02-01

    Studies of foraminiferal distribution and abundance have typically employed a procedure (standard method) that entails counting approximately 300 specimens from a size range greater than some specified minimum (commonly 63 or 125 ..mu..m). This method fails to take into account that foraminifera may be found only within certain size fractions, either because of species specific size ranges or taphonomic processes (sorting, transport, abrasion). Use of a modified counting procedure (sieve method) takes into account foraminiferal size distributions. The sieve method uses counts of up to 300 specimens in each sand-size fraction (0.125-0.25, 0.25-0.5, 0.5-1, 1-2 mm) of each sample. Counts are then totaled for each sample (up to 1200 specimens per site) and used in determination of species abundances for each site. The sieve method has been of considerable utility in recognition of a foraminiferal bathymetric zonation preserved in sediment assemblages from fringing reef environments at Discovery Bay, north Jamaica. Well-documented reef zones (based on corals and physiography) are clearly defined in Q-mode cluster analysis (UPGMA) of species abundances determined using the sieve method. In contrast, individual fore reef zones are not recognized in cluster analysis of foraminiferal species abundances based on the standard method, nor by cluster analysis of species abundances within individual size fractions.

  12. Foraminiferal survival after long term experimentally induced anoxia

    Directory of Open Access Journals (Sweden)

    D. Langlet

    2013-06-01

    Full Text Available Anoxia has been successfully induced in four benthic chambers installed on the Northern Adriatic seafloor from 1 week to 10 months. To accurately determine whether benthic foraminifera can survive experimentally induced prolonged anoxia, the CellTrackerGreen method has been applied. Numerous individuals have been found living at all sampling times and at all sampling depths, showing that benthic foraminifera can survive up to 10 months of anoxia with co-occurring hydrogen sulphides. However, foraminiferal standing stocks decrease with sampling time in an irregular way. A large difference in standing stock between two cores samples in initial conditions indicates the presence of a large spatial heterogeneity of the foraminiferal faunas. An unexpected increase in standing stocks after 1 month is tentatively interpreted as a reaction to increased food availability due to the massive mortality of infaunal macrofaunal organisms. After this, standing stocks decrease again in a core sampled after 2 months of anoxia, to attain a minimum in the cores sampled after 10 months. We speculate that the trend of overall decrease of standing stocks is not due to the adverse effects of anoxia and hydrogen sulphides, but rather due to a continuous diminution of labile organic matter.

  13. Spatial Patterns in the Distribution, Diversity and Abundance of Benthic Foraminifera around Moorea (Society Archipelago, French Polynesia).

    Science.gov (United States)

    Fajemila, Olugbenga T; Langer, Martin R; Lipps, Jere H

    2015-01-01

    Coral reefs are now subject to global threats and influences from numerous anthropogenic sources. Foraminifera, a group of unicellular shelled organisms, are excellent indicators of water quality and reef health. Thus we studied a set of samples taken in 1992 to provide a foraminiferal baseline for future studies of environmental change. Our study provides the first island-wide analysis of shallow benthic foraminifera from around Moorea (Society Archipelago). We analyzed the composition, species richness, patterns of distribution and abundance of unstained foraminiferal assemblages from bays, fringing reefs, nearshore and back- and fore-reef environments. A total of 380 taxa of foraminifera were recorded, a number that almost doubles previous species counts. Spatial patterns of foraminiferal assemblages are characterized by numerical abundances of individual taxa, cluster groups and gradients of species richness, as documented by cluster, Fisher α, ternary plot and Principal Component Analyses (PCA). The inner bay inlets are dominated by stress-tolerant, mostly thin-shelled taxa of Bolivina, Bolivinella, Nonionoides, Elongobula, and Ammonia preferring low-oxygen and/or nutrient-rich habitats influenced by coastal factors such as fresh-water runoff and overhanging mangroves. The larger symbiont-bearing foraminifera (Borelis, Amphistegina, Heterostegina, Peneroplis) generally live in the oligotrophic, well-lit back- and fore-reef environments. Amphisteginids and peneroplids were among the few taxa found in the bay environments, probably due to their preferences for phytal substrates and tolerance to moderate levels of eutrophication. The fringing reef environments along the outer bay are characterized by Borelis schlumbergeri, Heterostegina depressa, Textularia spp. and various miliolids which represent a hotspot of diversity within the complex reef-lagoon system of Moorea. The high foraminiferal Fisher α and species richness diversity in outer bay fringing reefs

  14. Spatial Patterns in the Distribution, Diversity and Abundance of Benthic Foraminifera around Moorea (Society Archipelago, French Polynesia.

    Directory of Open Access Journals (Sweden)

    Olugbenga T Fajemila

    Full Text Available Coral reefs are now subject to global threats and influences from numerous anthropogenic sources. Foraminifera, a group of unicellular shelled organisms, are excellent indicators of water quality and reef health. Thus we studied a set of samples taken in 1992 to provide a foraminiferal baseline for future studies of environmental change. Our study provides the first island-wide analysis of shallow benthic foraminifera from around Moorea (Society Archipelago. We analyzed the composition, species richness, patterns of distribution and abundance of unstained foraminiferal assemblages from bays, fringing reefs, nearshore and back- and fore-reef environments. A total of 380 taxa of foraminifera were recorded, a number that almost doubles previous species counts. Spatial patterns of foraminiferal assemblages are characterized by numerical abundances of individual taxa, cluster groups and gradients of species richness, as documented by cluster, Fisher α, ternary plot and Principal Component Analyses (PCA. The inner bay inlets are dominated by stress-tolerant, mostly thin-shelled taxa of Bolivina, Bolivinella, Nonionoides, Elongobula, and Ammonia preferring low-oxygen and/or nutrient-rich habitats influenced by coastal factors such as fresh-water runoff and overhanging mangroves. The larger symbiont-bearing foraminifera (Borelis, Amphistegina, Heterostegina, Peneroplis generally live in the oligotrophic, well-lit back- and fore-reef environments. Amphisteginids and peneroplids were among the few taxa found in the bay environments, probably due to their preferences for phytal substrates and tolerance to moderate levels of eutrophication. The fringing reef environments along the outer bay are characterized by Borelis schlumbergeri, Heterostegina depressa, Textularia spp. and various miliolids which represent a hotspot of diversity within the complex reef-lagoon system of Moorea. The high foraminiferal Fisher α and species richness diversity in outer bay

  15. Spatial Patterns in the Distribution, Diversity and Abundance of Benthic Foraminifera around Moorea (Society Archipelago, French Polynesia)

    Science.gov (United States)

    2015-01-01

    Coral reefs are now subject to global threats and influences from numerous anthropogenic sources. Foraminifera, a group of unicellular shelled organisms, are excellent indicators of water quality and reef health. Thus we studied a set of samples taken in 1992 to provide a foraminiferal baseline for future studies of environmental change. Our study provides the first island-wide analysis of shallow benthic foraminifera from around Moorea (Society Archipelago). We analyzed the composition, species richness, patterns of distribution and abundance of unstained foraminiferal assemblages from bays, fringing reefs, nearshore and back- and fore-reef environments. A total of 380 taxa of foraminifera were recorded, a number that almost doubles previous species counts. Spatial patterns of foraminiferal assemblages are characterized by numerical abundances of individual taxa, cluster groups and gradients of species richness, as documented by cluster, Fisher α, ternary plot and Principal Component Analyses (PCA). The inner bay inlets are dominated by stress-tolerant, mostly thin-shelled taxa of Bolivina, Bolivinella, Nonionoides, Elongobula, and Ammonia preferring low-oxygen and/or nutrient-rich habitats influenced by coastal factors such as fresh-water runoff and overhanging mangroves. The larger symbiont-bearing foraminifera (Borelis, Amphistegina, Heterostegina, Peneroplis) generally live in the oligotrophic, well-lit back- and fore-reef environments. Amphisteginids and peneroplids were among the few taxa found in the bay environments, probably due to their preferences for phytal substrates and tolerance to moderate levels of eutrophication. The fringing reef environments along the outer bay are characterized by Borelis schlumbergeri, Heterostegina depressa, Textularia spp. and various miliolids which represent a hotspot of diversity within the complex reef-lagoon system of Moorea. The high foraminiferal Fisher α and species richness diversity in outer bay fringing reefs

  16. Spatial heterogeneity of benthic community assemblages with an emphasis on reef algae at French Frigate Shoals, Northwestern Hawai`ian Islands

    Science.gov (United States)

    Vroom, Peter S.; Page, Kimberly N.; Peyton, Kimberly A.; Kukea-Shultz, J. Kanekoa

    2005-12-01

    Reefs in tropical atoll systems have historically been described on a geomorphic basis, and segregated into loosely defined fore-reef, back-reef, and lagoonal reef zones. However, recent oceanographic monitoring data have shown that physical factors within a single geomorphic zone can vary significantly, calling into question whether benthic communities within a single zone are biologically similar. To determine the amount of benthic variability that may occur in a geomorphic zone, percent cover of benthic organisms was determined at the species level for 28 sites in three geomorphic zones at French Frigate Shoals, Northwestern Hawai‘ian Islands. Multivariate statistical analyses found most windward fore-reef and back-reef sites to be statistically similar, but considerable variation to exist among sites within calmer lagoonal areas. Surveys revealed macroalgae to dominate over scleractinian coral species at the majority of sites in this healthy, subtropical reef system, although select lagoonal areas were dominated by dense coral communities.

  17. A multivariate statistical study with a factor analysis of recent planktonic foraminiferal distribution in the Coromandel Coast of India

    OpenAIRE

    Jayalakshmy, K.V.; Kameswara Rao, K.

    1991-01-01

    A study of planktonic foraminiferal assemblages from 19 stations in the neritic and oceanic regions off the Coromandel Coast, Bay of Bengal has been made using a multivariate statistical method termed as factor analysis. On the basis of abundance, 17 foraminiferal species, species were clustered into 5 groups with row normalisation and varimax rotation for Q-mode factor analysis. The 19 stations were also grouped into 5 groups with only 2 groups statistically significant using column normalis...

  18. Multivariate statistical study with a factor analysis of foraminiferal fauna from the Chilka Lake, India

    Digital Repository Service at National Institute of Oceanography (India)

    Jayalakshmy, K.V.; Rao, K.K.

    Foraminiferal fauna from the surface sediments of the Chilka Lake along the east coast of India has been studied as regards distribution of its assemblages. From Q-mode factor analysis of the data, eight significant factor groups for species have...

  19. BENTHIC FORAMINIFERA AS INDICATORS OF PALEOECOLOGICAL BOTTOM CONDITIONS IN THE SERRAVALLIAN TREMITI SECTIONS (EASTERN MEDITERRANEAN, ITALY

    Directory of Open Access Journals (Sweden)

    BIANCA RUSSO

    2002-07-01

    Full Text Available Quantitative analysis of  benthic foraminifera from the Serravallian S. Nicola composite section (Tremiti Islands, Adriatic Sea and about 37 m thick, pointed out changes of bottom paleoecological conditions in this eastern Mediterranean area during the analyzed time interval. Benthic foraminiferal assemblages are typical of bathyal environment and indicate a constant paleobathymetry of about 1,000 m. Changes in benthic foraminiferal assemblages allowed us to identify five intervals,  which were calibrated on the astrochronological scale to reconstruct paleoecological evolution of bottom conditions. In particular starting from the base of the section the following different bottom conditions have been identified: 1 between about 12.62  to about 12.29 Ma high surface productivity, active bottom water circulation and, consequently, moderate bottom food supply; this paleoenvironment slightly changed  between about 12.49 and 12.29 Ma, where benthic assemblages testify unstable bottom conditions with periods of active circulation (relative abundance of Cibicidoides wuellerstorfi, alternated with periods of sluggish circulation  (peaks of Bulimina subulata group; 2 relatively oxygenated paleoenvironment together with low food supply between about  12.29 - 12.08 Ma; 3 increase of organic matter content (abundance of  U. peregrina-pygmaea, due to higher surface productivity and/or greater preservation of organic matter at bottom from 12.08 to 11.81 Ma; 4 relatively oxygenated conditions with low food supply from 11.81 to about 11.45 Ma; 5 similar conditions to those of the basal part (about 12.62  - 12.29 Ma of the section from about 11.45 to 11.10 Ma, but with an increase of organic matter content. Finally, the comparison between the paleoecological reconstruction of the S. Nicola composite section and Ras il-Pellegrin (Malta composite section (reported in this volume in  the interval between about 12.6 and 12.2 Ma, pointed out very different

  20. The reciprocity between coiling direction and dimorphic reproduction in benthic foraminifera

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Khare, N.

    , an attempt is made to study the relationship between mode of reproduction (sexual/asexual) and coiling direction (dextral / sinistral) in the benthic foraminiferal species Rotalidium annectens (Parker and Jones). Proloculus (initial chamber) size is taken...

  1. Between-Habitat Variation of Benthic Cover, Reef Fish Assemblage and Feeding Pressure on the Benthos at the Only Atoll in South Atlantic: Rocas Atoll, NE Brazil

    OpenAIRE

    Longo, G. O.; Morais, R. A.; C D L Martins; Mendes, T. C.; Aued, A. W.; Cândido, D. V.; Oliveira, J. C.; L T Nunes; Fontoura, L.; M N Sissini; Teschima, M. M.; M. B. Silva; Ramlov, F.; Gouvea, L. P.; Ferreira, C. E. L.

    2015-01-01

    The Southwestern Atlantic harbors unique and relatively understudied reef systems, including the only atoll in South Atlantic: Rocas atoll. Located 230 km off the NE Brazilian coast, Rocas is formed by coralline red algae and vermetid mollusks, and is potentially one of the most "pristine" areas in Southwestern Atlantic. We provide the first comprehensive and integrative description of the fish and benthic communities inhabiting different shallow reef habitats of Rocas. We studied two contras...

  2. Cold seep and oxygen minimum zone associated sources of margin heterogeneity affect benthic assemblages, diversity and nutrition at the Cascadian margin (NE Pacific Ocean)

    OpenAIRE

    Guilini, K.; Levin, L. A.; Vanreusel, A.

    2012-01-01

    Hydrate Ridge (HR), located on the northeastern Pacific margin off Oregon, is characterized by the presence of outcropping hydrates and active methane seepage. Additionally, permanent low oxygen conditions overlay the benthic realm. This study evaluated the relative influence of both seepage and oxygen minima as sources of habitat heterogeneity and potential stress-inducing features on the bathyal metazoan benthos (primarily nematodes) at three different seep and non-seep HR locations, expose...

  3. Response of Benthic Foraminifera to Organic Matter Quantity and Quality and Bioavailable Concentrations of Metals in Aveiro Lagoon (Portugal)

    Science.gov (United States)

    Martins, Maria Virgínia Alves; Silva, Frederico; Laut, Lazaro L. M.; Frontalini, Fabrizio; Clemente, Iara M. M. M.; Miranda, Paulo; Figueira, Rubens; Sousa, Silvia H. M.; Dias, João M. Alveirinho

    2015-01-01

    This work analyses the distribution of living benthic foraminiferal assemblages of surface sediments in different intertidal areas of Ria de Aveiro (Portugal), a polihaline and anthropized coastal lagoon. The relationships among foraminiferal assemblages in association with environmental parameters (temperature, salinity, Eh and pH), grain size, the quantity and quality of organic matter (enrichment in carbohydrates, proteins and lipids), pollution caused by metals, and mineralogical data are studied in an attempt to identify indicators of adaptability to environmental stress. In particular, concentrations of selected metals in the surficial sediment are investigated to assess environmental pollution levels that are further synthetically parameterised by the Pollution Load Index (PLI). The PLI variations allowed the identification of five main polluted areas. Concentrations of metals were also analysed in three extracted phases to evaluate their possible mobility, bioavailability and toxicity in the surficial sediment. Polluted sediment in the form of both organic matter and metals can be found in the most confined zones. Whereas enrichment in organic matter and related biopolymers causes an increase in foraminifera density, pollution by metals leads to a decline in foraminiferal abundance and diversity in those zones. The first situation may be justified by the existence of opportunistic species (with high reproduction rate) that can live in low oxic conditions. The second is explained by the sensitivity of some species to pressure caused by metals. The quality of the organic matter found in these places and the option of a different food source should also explain the tolerance of several species to pollution caused by metals, despite their low reproductive rate in the most polluted areas. In this study, species that are sensitive and tolerant to organic matter and metal enrichment are identified, as is the differential sensitivity/tolerance of some species to

  4. Benthic foraminifera at the Paleocene/Eocene thermal maximum in the western Tethys (Forada section): variability in climate and productivity

    Science.gov (United States)

    Giusberti, L.; Boscolo Galazzo, F.; Thomas, E.

    2015-09-01

    The Forada section (northeastern Italy) provides a continuous, expanded deep-sea record of the Paleocene/Eocene thermal maximum (PETM) in the central-western Tethys. We combine a new, high resolution, benthic foraminiferal assemblage record with published calcareous plankton, mineralogical and biomarker data to document climatic and environmental changes across the PETM, highlighting the benthic foraminiferal extinction event (BEE). The onset of the PETM, occurring ~ 30 kyr after a precursor event, is marked by a thin, black, barren clay layer, possibly representing a brief pulse of anoxia and carbonate dissolution. The BEE occurred within the 10 cm interval including this layer. During the first 3.5 kyr of the PETM several agglutinated recolonizing taxa show rapid species turnover, indicating a highly unstable, CaCO3-corrosive environment. Calcareous taxa reappeared after this interval, and the next ~ 9 kyr were characterized by rapid alternation of peaks in abundance of various calcareous and agglutinant recolonizers. These observations suggest that synergistic stressors including deep water CaCO3-corrosiveness, low oxygenation, and high environmental instability caused the extinction. Combined faunal and biomarker data (BIT index, higher plant n-alkane average chain length) and the high abundance of the mineral chlorite suggest that erosion and weathering increased strongly at the onset of the PETM, due to an overall wet climate with invigorated hydrological cycle, which led to storm flood-events carrying massive sediment discharge into the Belluno Basin. This interval was followed by the core of the PETM, characterized by four precessionally paced cycles in CaCO3%, hematite%, δ13C, abundant occurrence of opportunistic benthic foraminiferal taxa, as well as calcareous nannofossil and planktonic foraminiferal taxa typical of high productivity environments, radiolarians, and lower δDn-alkanes. We interpret these cycles as reflecting alternation between an

  5. Larger benthic foraminifera of the Paleogene Promina Beds (Croatia)

    Science.gov (United States)

    Cosovic, V.; Mrinjek, E.; Drobne, K.

    2012-04-01

    In order to add more information about complex origin of Promina Beds (traditionally interpreted as Paleogene molasse of Dinarides), two sections (Lišani Ostrovački and Ostrovica, Central Dalmatia, Croatia) have been studied in detail. Sampled carbonate sequences contain predominantly coralline red algae, larger benthic foraminifera and corals. Based on sedimentary textures, nummulitid (Nummulites s.str and Asterigerina sp.) test shapes and the associated skeletal components, altogether three types of the Middle Eocene (Lutetian to Bartonian) facies were recognized. The Ostrovica section is composed of alternating couples of marly limestones and marls, several decimeters thick with great lateral continuity. Two facies which vertically alternate are recognized as Nummulites - Asterigerina facies, where patchily dispersed large, robust and party reworked larger benthic foraminifera constitute 20% and small bioclasts (fomaniniferal fragments and whole tests less than 3 mm in diameters) 10% of rock volume and, Coral - Red algal facies with coral fragments of solitary and colonial taxa up to 1 cm in size constitute 5 - 40%, red algae 15 - 60% and lager benthic foraminifera up to 5% of rock volume. The textural and compositional differences among the facies suggest rhythmic exchanges of conditions that characterize shallower part of the mesophotic zone with abundant nummulithoclasts with deeper mesophotic, lime mud-dominated settings where nummulitids with the flat tests, coralline red algae and scleractinian corals are common. The scleractinian corals (comprising up to 20% of rock volume) encrusted by foraminifera (Acervulina, Haddonia and nubeculariids) or coralline red algae and foraminiferal assemblage made of orthophragminid and nummulitid tests scattered in matrix, are distributed uniformly throughout the studied Lišani Ostrovački section. In the central part of section, wavy to smooth thin (< 1 mm) crusts (laminas) alternating with encrusted corals occur. The

  6. Late Paleocene-middle Eocene benthic foraminifera on a Pacific seamount (Allison Guyot, ODP Site 865): Greenhouse climate and superimposed hyperthermal events

    Science.gov (United States)

    Arreguín-Rodríguez, Gabriela J.; Alegret, Laia; Thomas, Ellen

    2016-03-01

    We investigated the response of late Paleocene-middle Eocene (~60-37.5 Ma) benthic foraminiferal assemblages to long-term climate change and hyperthermal events including the Paleocene-Eocene Thermal Maximum (PETM) at Ocean Drilling Program (ODP) Site 865 on Allison Guyot, a seamount in the Mid-Pacific Mountains. Seamounts are isolated deep-sea environments where enhanced current systems interrupt bentho-pelagic coupling, and fossil assemblages from such settings have been little evaluated. Assemblages at Site 865 are diverse and dominated by cylindrical calcareous taxa with complex apertures, an extinct group which probably lived infaunally. Dominance of an infaunal morphogroup is unexpected in a highly oligotrophic setting, but these forms may have been shallow infaunal suspension feeders, which were ecologically successful on the current-swept seamount. The magnitude of the PETM extinction at Site 865 was similar to other sites globally, but lower diversity postextinction faunas at this location were affected by ocean acidification as well as changes in current regime, which might have led to increased nutrient supply through trophic focusing. A minor hyperthermal saw less severe effects of changes in current regime, with no evidence for carbonate dissolution. Although the relative abundance of infaunal benthic foraminifera has been used as a proxy for surface productivity through bentho-pelagic coupling, we argue that this proxy can be used only in the absence of changes in carbonate saturation and current-driven biophysical linking.

  7. Foraminiferal record of anthropogenic environmental changes in the northeastern Adriatic Sea (Panzano Bay, Gulf of Trieste, Italy)

    Science.gov (United States)

    Vidovic, Jelena; Cosovic, Vlasta; Kern, Vieana; Gallmetzer, Ivo; Haselmair, Alexandra; Zuschin, Martin

    2016-04-01

    The northern Adriatic Sea is one of the world's largest modern epicontinental seas and a young marine ecosystem that has been subject to various natural and anthropogenic processes during the Holocene: marine transgression, regional climate fluctuations, urbanisation and pollution. The Gulf of Trieste, located in the northeastern part, presents the area of particular interest, as it is a shallow and sheltered embayment, prone to the accumulation of pollutants, populated for at least the last 2000 years and with recent anthropogenic pressure coming from several rivers, ports and industrial zones. The aim of this multidisciplinary study is to provide a high-resolution record of these processes using benthic foraminiferal assemblages, geochemical proxies (trace metals, nutrients and pollutants), sedimentological (sedimentation rates) and time-averaging data (from dated mollusc shells). One core of 1.5 m length was taken at the sampling station Panzano Bay, northernmost part of the Gulf of Trieste, at the water depth of 12.5 m. The sedimentation rate is estimated to be 2.5 mm/year, based on 210Pb sediment dating, while dating of the molluscs shells revealed the age at the bottom of the core to be approximately 500 years. The core was sliced into smaller subsamples, and four sediment fractions of each subsample (63, 125, 250 and 500 μm) were analysed for standard properties of the foraminiferal community (faunal composition, absolute and relative abundances of species, biodiversity indices), in order to make comparison with relevant physical and geochemical properties of the sediment. The results concerning changes in foraminiferal species composition, their abundance and biodiversity, supported by statistical analyses (cluster analysis, NMDS, PCA), allow identification of three major foraminiferal associations: 1) 80-150 cm - the oldest association is dominated by opportunistic genera ans species, characteristic for unstable environments: Valvulineria sp. (25

  8. Benthic Foraminifera along a depth transect in western Bahrain: seasonal variations and environmental assessment

    Science.gov (United States)

    Muhammad, Arslan; Kaminski, Michael; Tawabini, Bassam; Ramadan, Khalid Al; Babalola, Lamidi; Frontalini, Fabrizio

    2015-04-01

    We surveyed living benthic foraminifera in a depth transect off western Bahrain (Arabian Gulf) with the aim of understanding the seasonal population dynamics and environmental parameters. In winter, the population was found to be highest due to the large number of rotaliids, followed by miliolids. In each season, the population was found to increase along the depth transect due to the higher number of juveniles. A strong correlation is observed between foraminiferal population and sediment grain size - the juveniles are most abundant on coarser-sandy substrate. The population decreases in the spring and is lowest in the summer. Finally, the living population recovered again in the autumn with increasing juveniles/adult ratios along the depth transect. Results of species consistency and relative abundance showed that Ammonia was consistent from the shallowest to the deepest station, whereas miliolids started appearing in the deeper stations. The average numbers of Elphidium and Peneroplis also increased along the depth transect. Another seasonal effect is that juveniles of Ammonia tepida are found during each season reflecting its reproduction throughout the year, whereas Brizalina pacifica was only found during spring and autumn. The study of environmental parameters reveals that the site is subjected to eutrophication i.e. nitrates and sulfates, however, pollution by heavy metals and hydrocarbons is not significant. An assessment of 63 heavy metals in sediment samples showed that none of the metals had concentrations higher than the internationally accepted norms, which is further confirmed by values of the Foraminiferal Deformities Index of less than 2%. Likewise, no hydrocarbons were detected in the water or sediment samples. Therefore, it is concluded that the site in Bahrain is not yet adversely affected by human development, and therefore can provide baseline information for future comparison and assessment of foraminiferal assemblages in contaminated zones

  9. Comparison of live and dead molluscan assemblages suggests recent human-driven decline in benthic diversity in Phetchaburi (NW Gulf of Thailand)

    Science.gov (United States)

    Negri, Mauro Pietro; Sanfilippo, Rossana; Basso, Daniela; Rosso, Antonietta

    2015-12-01

    Dead and live molluscan assemblages from the coastal area of Phetchaburi (NW Gulf of Thailand) were compared by means of multivariate analysis. Seven thanatofacies were recognized, thriving in the area after the 1960s. Five of them, scattered along the tidal flat, represent oligotypic intertidal biotopes linked to a variety of environmental factors; the remaining two mirror high-diversity infralittoral associations. Conversely, only two poor, ill-defined biofacies thrive at present between the intertidal and the shallow infralittoral zones, somewhat resembling two of the thanatofacies. Diversity indexes reveal a dramatic biodiversity decline occurred from the 1960s onwards, far beyond the effects of time-averaging and accumulation. The responsibility for this reduction is largely attributable to the high impact of human activities, such as the intensive sea bottom trawling, the wastewaters from aquaculture (shrimp and fish ponds) and dense coastal villages, and, at a minor extent, the digging of edible molluscs from the tidal flat.

  10. Benthic Assemblages of the Anton Dohrn Seamount (NE Atlantic: Defining Deep-Sea Biotopes to Support Habitat Mapping and Management Efforts with a Focus on Vulnerable Marine Ecosystems.

    Directory of Open Access Journals (Sweden)

    Jaime S Davies

    Full Text Available In 2009 the NW and SE flanks of Anton Dohrn Seamount were surveyed using multibeam echosounder and video ground-truthing to characterise megabenthic biological assemblages (biotopes and assess those which clearly adhere to the definition of Vulnerable Marine Ecosystems, for use in habitat mapping. A combination of multivariate analysis of still imagery and video ground-truthing defined 13 comprehensive descriptions of biotopes that function as mapping units in an applied context. The data reveals that the NW and SE sides of Anton Dohrn Seamount (ADS are topographically complex and harbour diverse biological assemblages, some of which agree with current definitions of 'listed' habitats of conservation concern. Ten of these biotopes could easily be considered Vulnerable Marine Ecosystems; three coral gardens, four cold-water coral reefs, two xenophyophore communities and one sponge dominated community, with remaining biotopes requiring more detailed assessment. Coral gardens were only found on positive geomorphic features, namely parasitic cones and radial ridges, found both sides of the seamount over a depth of 1311-1740 m. Two cold-water coral reefs (equivalent to summit reef were mapped on the NW side of the seamount; Lophelia pertusa reef associated with the cliff top mounds at a depth of 747-791 m and Solenosmilia variabilis reef on a radial ridge at a depth of 1318-1351 m. Xenophyophore communities were mapped from both sides of the seamount at a depth of 1099-1770 m and were either associated with geomorphic features or were in close proximity (< 100 m to them. The sponge dominated community was found on the steep escarpment either side of the seamount over at a depth of 854-1345 m. Multivariate diversity revealed the xenophyophore biotopes to be the least diverse, and a hard substratum biotope characterised by serpulids and the sessile holothurian, Psolus squamatus, as the most diverse.

  11. Water masses in Kangerlussuaq, a large fjord in West Greenland: the processes of formation and the associated foraminiferal fauna

    DEFF Research Database (Denmark)

    Nielsen, Morten Holtegaard; Erbs-Hansen, Dorthe Reng; Knudsen, Karen Luise

    2010-01-01

    The water masses in Kangerlussuaq (Søndre Strømfjord) in West Greenland were studied during both a summer and a winter field survey. In order to obtain an improved understanding of the relationship between the physical oceanography and modern foraminiferal assemblage distributions, conductivity...

  12. Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach

    NARCIS (Netherlands)

    Mojtahid, Meryem; Manceau, Rose; Schiebel, Ralf; Hennekam, Rick; De Lange, Gert J.

    2015-01-01

    Over the past 13 ka, the hydrology for the southeastern Mediterranean was mainly regulated by Nile River runoff, which in turn was controlled by climate forcing. Being affected by orbital forcing, and the position of the Intertropical Convergence Zone (ITCZ), planktic foraminiferal data (assemblages

  13. Effect of Ocean Acidification and pH Fluctuations on the Growth and Development of Coralline Algal Recruits, and an Associated Benthic Algal Assemblage.

    Directory of Open Access Journals (Sweden)

    Michael Y Roleda

    Full Text Available Coralline algae are susceptible to the changes in the seawater carbonate system associated with ocean acidification (OA. However, the coastal environments in which corallines grow are subject to large daily pH fluctuations which may affect their responses to OA. Here, we followed the growth and development of the juvenile coralline alga Arthrocardia corymbosa, which had recruited into experimental conditions during a prior experiment, using a novel OA laboratory culture system to simulate the pH fluctuations observed within a kelp forest. Microscopic life history stages are considered more susceptible to environmental stress than adult stages; we compared the responses of newly recruited A. corymbosa to static and fluctuating seawater pH with those of their field-collected parents. Recruits were cultivated for 16 weeks under static pH 8.05 and 7.65, representing ambient and 4× preindustrial pCO2 concentrations, respectively, and two fluctuating pH treatments of daily [Formula: see text] (daytime pH = 8.45, night-time pH = 7.65 and daily [Formula: see text] (daytime pH = 8.05, night-time pH = 7.25. Positive growth rates of new recruits were recorded in all treatments, and were highest under static pH 8.05 and lowest under fluctuating pH 7.65. This pattern was similar to the adults' response, except that adults had zero growth under fluctuating pH 7.65. The % dry weight of MgCO3 in calcite of the juveniles was reduced from 10% at pH 8.05 to 8% at pH 7.65, but there was no effect of pH fluctuation. A wide range of fleshy macroalgae and at least 6 species of benthic diatoms recruited across all experimental treatments, from cryptic spores associated with the adult A. corymbosa. There was no effect of experimental treatment on the growth of the benthic diatoms. On the community level, pH-sensitive species may survive lower pH in the presence of diatoms and fleshy macroalgae, whose high metabolic activity may raise the pH of the local microhabitat.

  14. Distribution of benthic foraminifera within oxygen minima zone, off central west coast, India

    Digital Repository Service at National Institute of Oceanography (India)

    Mazumder, A.; Henriques, P.J.; Nigam, R.

    A total of 128 surface sediment samples (76 grab and 52 core top samples) were analyzed for benthic foraminiferal contents from the region off Goa, India in the eastern Arabian Sea upto a water depth of 3300 m. 195 species of benthic foraminifera...

  15. Benthic diatoms in lakes

    OpenAIRE

    Gottschalk, Steffi

    2014-01-01

    In order to protect or improve surface waters ecosystem response to pressures needs to be quantified. Diatoms are frequently used for assessing ecological status in streams and for reconstructing water quality of lakes. However, ecological status assessment of European lakes based on extant diatom assemblages is rare. The overall aim of this thesis is to facilitate the application of benthic diatoms in water quality assessment of boreal lakes, using methods developed for stream assessmen...

  16. Bipolar gene flow in deep-sea benthic foraminifera

    DEFF Research Database (Denmark)

    Pawlowski, J.; Fahrni, J.; Lecroq, B.;

    2007-01-01

    -sea foraminiferal species (Epistominella exigua, Cibicides wuellerstorfi and Oridorsalis umbonatus), separated by distances of up to 17 000 km. Our results contrast with the substantial level of cryptic diversity usually revealed by molecular studies, of shallow-water benthic and planktonic marine organisms. The...

  17. Temporal variability in living deep-sea benthic foraminifera: a review

    Science.gov (United States)

    Gooday, Andrew J.; Rathburn, Anthony E.

    1999-05-01

    of 25.5 cm 2 surface area). Seasonal phytodetrital pulses to the deep-seafloor, and hence, foraminiferal population dynamics, are not entirely predictable. Being dependent on climatic and upper-ocean processes, they vary in intensity from year to year and occasionally (e.g., at the Porcupine Abyssal Plain (PAP) in 1997) fail to materialise. Foraminiferal responses to irregular (non-seasonal) organic matter inputs are poorly-known. However, there is some evidence that whale falls, turbidite deposits, hydrothermal vents and seeps are exploited by species typical of organically-enriched, low-oxygen environments rather than by a specialised fauna. Fossil foraminiferal assemblages from bathyal and abyssal environments may provide evidence for an increase or decrease in the seasonality of surface production as well as for longer-term changes in palaeoproductivity. However, the accurate interpretation of this record depends on filling the many gaps which remain in our understanding of relations between benthic foraminiferal ecology and seasonal phenomena in the deep ocean.

  18. Planktic foraminiferal response to the Latest Danian Event in the Pacific Ocean (ODP Site 1210)

    Science.gov (United States)

    Jehle, Sofie; Bornemann, André; Deprez, Arne; Speijer, Robert

    2015-04-01

    During the Paleocene the marine ecosystem was disturbed by several transient climate events, e.g. the Dan-C2 (65.2 Ma), the Latest Danian Event (LDE, 61.75 Ma), and most known, the Paleocene-Eocene Thermal Maximum (PETM, 56 Ma). So far the LDE (or "Top Chron 27n Event") has rarely been studied in deep-sea sites with respect to the evolution and the paleoecology of planktic foraminifera. The event has already been described from Zumaia/Spain, Bjala/Bulgaria, Egypt, Shatsky Rise and Walvis Ridge. In the deep-sea the LDE is usually characterized by two distinctive Fe peaks in XRF core scanning data, paralleled by a prominent (~0.7 ‰) negative δ13C excursion (CIE) in benthic foraminifera (Westerhold et al., 2008, 2011). Benthic foraminiferal δ18O data from nearby ODP Site 1209 suggest a bottom-water temperature rise of ~2°C accompanying the negative CIE. Thus, the LDE has been considered as a further potential Paleocene "hyperthermal". Here we present data from ODP Site 1210 of the biotic response (planktic foraminifera assemblages), carbonate preservation as well as δ18O and δ13C isotope signals of the surface, subsurface and benthic taxa covering a time span of about 900 kyr around the LDE. Among others, it is mainly investigated to what extent the LDE influences the ocean ecology and especially the surface waters. Trends of both δ18O and δ13C of planktic and benthic foraminifera show negative shifts at the onset of the LDE. A 0.6‰ drop within 100 ky in planktic δ18O data suggest a temperature rise of ~2.5°C, whereas benthic foraminifera bottom water temperatures confirm a ~2°C rise like measured at Site 1209. δ13C variation is more abrupt and pronounced than the δ18O shift at the base of the LDE. The decreasing δ13C gradient between surface and subsurface dwelling foraminifera suggests a weaker and or shallower thermocline. Thermocline dwelling asymbiotic Parasubbotina rise in abundance simultaneously to the decrease in the δ13C gradient which may

  19. Benthic foraminifera (Protista) as tools in deep-water palaeoceanography: environmental influences on faunal characteristics.

    Science.gov (United States)

    Gooday, Andrew J

    2003-01-01

    , particularly on continental margins where strong seafloor environmental gradients exist. Epifaunal species living on elevated substrata are directly exposed to bottom-water masses and flourish where suspended food particles are advected by strong currents. Biological interactions, e.g. predation and competition, must also play a role, although this is poorly understood and difficult to quantify. Despite often clear qualitative links between environmental and faunal parameters, the development of quantitative foraminiferal proxies remains problematic. Many of these difficulties arise because species can tolerate a wide range of non-optimal conditions and do not exhibit simple relationships with particular parameters. Some progress has been made, however, in formulating proxies for organic fluxes and bottom-water oxygenation. Flux proxies are based on the Benthic Foraminiferal Accumulation Rate and multivariate analyses of species data. Oxygen proxies utilise the relative proportions of epifaunal (oxyphilic) and deep infaunal (low-oxygen tolerant) species. Yet many problems remain, particularly those concerning the calibration of proxies, the closely interwoven effects of oxygen and food availability, and the relationship between living assemblages and those preserved in the permanent sediment record. PMID:14601411

  20. Geochemical evidence for non-marine depositional environment of foraminiferal fossils from the Nihewan Basin, China

    Institute of Scientific and Technical Information of China (English)

    王世杰; 刘秀明; 贾玉鹤; 董丽敏; 季宏兵

    2002-01-01

    From the first finding in 1970s, the findings of foraminiferal fossil assemblages in inland basins have been reported from time to time, especially in recent years. The debates on the depositional environment of foraminiferal fossils have become the hot spot of researches again in China. Based on the researches of trace element geochemistry and electron scanning microscope of shells of Quaternary foraminiferal fossils from the Xiaodukou section in the inland Nihewan basin, the original 87Sr/86Sr and other geochemical information of shells were believed to be preserved well and could be used to rebuild the geochemistry of contemporary waters where foraminifera deposited, although there existed some effects of burial diagenesis on the geochemistry of shells to a certain extent. The 87Sr/86Sr ratios of well-preserved Xiaodukou foraminiferal shells were measured, giving a range of 0.711190±25-0.712018±14, apparently higher than the value of contemporary seawater (0.709087-0.709147) and similar to that of the Sanggan River, proving that it represented the value of the ancient lacustrine water. The hyperbolic mixing models of 87Sr/86Sr-palaeosalinity and 87Sr/86Sr-Sr/Ca indicated that the contemporary waters where Xiaodukou foraminifera inhabited was an inland lake and there was no seawater input to the depositional environment.

  1. Evolution of southern Indian Ocean surface and deep waters during the paleogene as inferred from foraminiferal stable isotope ratios

    International Nuclear Information System (INIS)

    During ODP Leg 119, the southernmost pelagic record of carbonate sedimentation of Neogene-Paleogene age in the southern Indian Ocean was recovered at Site 744 (61 degree 34.6 minutes S, 80 degree 35.46 minutes E; water depth 2,307 m) and Site 738 (62 degree 42.54 minutes S, 82 degree 47.25 minutes E; water depth 2,252 m) in the southern part of the Kerguelen-Heard Plateau. Site 744 late Eocene-Miocene sequence and Site 738 Late Cretaceous- early Oligocene sequences contain continuous records of climatic events in East Antarctica during this time. Oxygen isotopic ratios of planktonic and benthic foraminifera suggest the following climatic changes: (1) a cool Paleocene, although with higher temperatures than those inferred from published Pacific and southern South Atlantic δ18O records; (2) the early Eocene was characterized by the warmest deep and surface waters of the Cenozoic, which were, similar in temperature to those from low latitude areas; (3) cooling began in the early-middle Eocene and continued through the remainder of the Eocene (Eocene Cibicidoides δ18O values are not very different from those of low-latitude sites); (4) a rapid increase in Cibicidoides δ18O values (1-1.5%) occurred in the early Oligocene of Site 744. Ice-rafted debris, first recorded in sediments just below the δ18O maximum, are also found in the early Oligocene sequence. Oligocene-early Miocene Cibicidoides δ18O values of about 2% and the presence of ice-rafted debris are considered evidence for glacial conditions in Antarctica. Planktonic foraminiferal assemblages indicate a similar climatic trend. Species diversity was highest during the latest Paleocene and earliest Eocene. It declined during the middle-late Eocene and the low diversity Oligocene faunas were dominated by a few globigerine taxa that are long-ranging and morphologically conservative

  2. Foraminiferal faunal estimates of paleotemperature: Circumventing the no-analog problem yields cool ice age tropics

    Science.gov (United States)

    Mix, A.C.; Morey, A.E.; Pisias, N.G.; Hostetler, S.W.

    1999-01-01

    The sensitivity of the tropics to climate change, particularly the amplitude of glacial-to-interglacial changes in sea surface temperature (SST), is one of the great controversies in paleoclimatology. Here we reassess faunal estimates of ice age SSTs, focusing on the problem of no-analog planktonic foraminiferal assemblages in the equatorial oceans that confounds both classical transfer function and modern analog methods. A new calibration strategy developed here, which uses past variability of species to define robust faunal assemblages, solves the no-analog problem and reveals ice age cooling of 5??to 6??C in the equatorial current systems of the Atlantic and eastern Pacific Oceans. Classical transfer functions underestimated temperature changes in some areas of the tropical oceans because core-top assemblages misrepresented the ice age faunal assemblages. Our finding is consistent with some geochemical estimates and model predictions of greater ice age cooling in the tropics than was inferred by Climate: Long-Range Investigation, Mapping, and Prediction (CLIMAP) [1981] and thus may help to resolve a long-standing controversy. Our new foraminiferal transfer function suggests that such cooling was limited to the equatorial current systems, however, and supports CLIMAP's inference of stability of the subtropical gyre centers.

  3. Constitution of fish assemblages in three nearshore habitats and the effect of benthic macroalgae on fish assemblages in Gouqi Island%拘杞岛近岸3种生境鱼类群落组成及岩礁区底栖海藻对鱼类群落结构的影响

    Institute of Scientific and Technical Information of China (English)

    王蕾; 章守宇; 汪振华; 王凯; 林军

    2011-01-01

    Macroalgae covering on the rocky reef around coast of Gouqi Island were surveyed and sampled through diving during 2005 to 2006 and May to June 2010, in order to find out the distribution, constitution and life history of macroalgae. Two composing patterns of macroalgae were shown in the subtidal zone of rocky reef; one was dominated by standing macroalgae Sargassum horneri; another was dominated by smaller macroalgaes, such as Ulva pertusa, which is widely distributed both in intertidal and subtidal zone. The life history of S. Horneri showed the four stages of the larger kelp bed: young seedling development period (August to September) ,slow growth period of seeding (October to February in next year) ,fast growth and reproduction period (March to May) .decomposing and declining period (June to July). The smaller kelp bed exists the whole year, without much difference to outside of the kelp bed. To estimate the composition of fish assemblages in three habitats around Gouqi Island nearshore, I. E. Rocky reef, sandy beach and mussel cultivation rafts,we sampled the fish assemblages in three habitats by combined gill nets every month from February 2009 to January 2010. The indexes of Jaccard similarity, Margalef richness and Shannon-wiener diversity were used to compare the variety of fish community structures among habitats, combined with statistical analysis of variance, UPGMA and nMDS. It showed that the differences of fish community structures among above three habitats were significant. The dominant fish species in rocky reef habitat were Sebastiscus marmoratus, Agrammus agrammus and N. Albiflora. Fish community was mainly based on the demersal omnivorous rocky fishes, which prey mainly on benthic invertebrates living on macroalgaes. The dominant fish species in sandy beach habitat were Paraplagusia japonica and Nibea albiflora. Fish community was mainly based on the mid-lower migration fishes. For fish assemblages in mussel cultivation raft habitat, which were

  4. Constitution of fish assemblages in three nearshore habitats and the effect of benthic macroalgae on fish assemblages in Gouqi Island%拘杞岛近岸3种生境鱼类群落组成及岩礁区底栖海藻对鱼类群落结构的影响

    Institute of Scientific and Technical Information of China (English)

    王蕾; 章守宇; 汪振华; 王凯; 林军

    2011-01-01

    Macroalgae covering on the rocky reef around coast of Gouqi Island were surveyed and sampled through diving during 2005 to 2006 and May to June 2010, in order to find out the distribution, constitution and life history of macroalgae. Two composing patterns of macroalgae were shown in the subtidal zone of rocky reef; one was dominated by standing macroalgae Sargassum horneri; another was dominated by smaller macroalgaes, such as Ulva pertusa, which is widely distributed both in intertidal and subtidal zone. The life history of S. Horneri showed the four stages of the larger kelp bed: young seedling development period (August to September) ,slow growth period of seeding (October to February in next year) ,fast growth and reproduction period (March to May) .decomposing and declining period (June to July). The smaller kelp bed exists the whole year, without much difference to outside of the kelp bed. To estimate the composition of fish assemblages in three habitats around Gouqi Island nearshore, I. E. Rocky reef, sandy beach and mussel cultivation rafts,we sampled the fish assemblages in three habitats by combined gill nets every month from February 2009 to January 2010. The indexes of Jaccard similarity, Margalef richness and Shannon-wiener diversity were used to compare the variety of fish community structures among habitats, combined with statistical analysis of variance, UPGMA and nMDS. It showed that the differences of fish community structures among above three habitats were significant. The dominant fish species in rocky reef habitat were Sebastiscus marmoratus, Agrammus agrammus and N. Albiflora. Fish community was mainly based on the demersal omnivorous rocky fishes, which prey mainly on benthic invertebrates living on macroalgaes. The dominant fish species in sandy beach habitat were Paraplagusia japonica and Nibea albiflora. Fish community was mainly based on the mid-lower migration fishes. For fish assemblages in mussel cultivation raft habitat, which were

  5. Uptake of phytodetritus by benthic foraminifera under oxygen depletion at the Indian margin (Arabian Sea)

    Science.gov (United States)

    Enge, A. J.; Witte, U.; Kucera, M.; Heinz, P.

    2014-04-01

    Benthic foraminifera in sediments on the Indian margin of the Arabian Sea, where the oxygen minimum zone (OMZ) impinges on the continental slope, are exposed to particularly severe levels of oxygen depletion. Food supply for the benthic community is high but delivered in distinct pulses during upwelling and water mixing events associated with summer and winter monsoon periods. In order to investigate the response by benthic foraminifera to such pulsed food delivery under oxygen concentrations of less than 0.1 mL L-1 (4.5 μmol L-1), an in situ isotope labeling experiment (13C, 15N) was performed on the western continental slope of India at 540 m water depth (OMZ core region). The assemblage of living foraminifera (>125 μm) in the uppermost centimeter at this depth is characterized by an unexpectedly high population density of 3982 individuals 10 cm-2 and a strong dominance by few calcareous species. For the experiment, we concentrated on the nine most abundant taxa, which constitute 93% of the entire foraminiferal population at 0-1 cm sediment depth. Increased concentrations of 13C and 15N in the cytoplasm indicate that all investigated taxa took up labeled phytodetritus during the 4 day experimental phase. In total, these nine species had assimilated 113.8 mg C m-2 (17.5% of the total added carbon). Uptake of nitrogen by the three most abundant taxa (Bolivina aff. B. dilatata, Cassidulina sp., Bulimina gibba) was 2.7 mg N m-2 (2% of the total added nitrogen). The response to the offered phytodetritus varied largely among foraminiferal species with Uvigerina schwageri being by far the most important species in short-term processing, whereas the most abundant taxa Bolivina aff. B. dilatata and Cassidulina sp. showed comparably low uptake of the offered food. We suggest the observed species-specific differences are related to species biomass and specific feeding preferences. In summary, the experiment in the OMZ core region shows rapid processing of fresh

  6. Temporal changes of environmental impact in the coastal marine area in front of a former mining zone, detected by means of benthic foraminifera

    Science.gov (United States)

    Romano, Elena; Bergamin, Luisa; Maggi, Chiara; Ausili, Antonella

    2016-04-01

    Benthic foraminifera are increasingly used to assess environmental quality of present and past marine environments. They are suitable for the study of ancient environments because their hard and small shells are preserved and abundant in sediment and an adequate number of them can be collected by small samples of sediment cores, supplying reliable data for a statistical approach. The study of foraminiferal assemblages, associated to sediment abiotic parameters, allows to define the anthropogenic impact along the time; reference conditions may be recognized in deep uncontaminated levels. The Sulcis Iglesiente Guspinese area (SW Sardinia, Italy) was affected in past times by intensive mining, which started in mid 19th century and ceased in 1990s. The marine area of Cala Domestica is located few kilometers from the mining district, where mainly galena and sphalerite were exploited. The area houses buildings for storage of minerals receives drainage material from mineral dumps determining a strong enrichment for several metals in the coastal sediments. Sediment core SI/69 was collected by means of vibrocorer in front of Cala Domestica beach, during a vast sampling survey aimed to environmental characterization of marine sediments. The core was subsampled in the laboratory, and a total of 28 levels were collected. Microfaunal, grain size and chemical (As, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Zn) analyses were carried out on different aliquots of the same level. The quantitative analysis on benthic foraminifera was based on the count of at least 300 specimens per sample. Faunal parameters such as Foraminiferal Number (FN i.e. number of specimens / 1 g dry sediment) and species diversity (- index and H-index) were considered as potential indicators of environmental status. Principal Component Analysis (PCA) showed a group of strongly correlated metals (Ba, Cd, Cu, Hg, Mn, Pb and Zn), associated to the superficial samples. These elements displayed a typical profile along

  7. Recent benthic foraminifera and sedimentary facies distribution of the Abu Dhabi (United Arab Emirates) coastline

    Science.gov (United States)

    Fiorini, Flavia; Lokier, Stephen W.

    2014-05-01

    The distribution of benthic foraminifera and sedimentary facies from Recent coastline environments adjacent to the coastline of Abu Dhabi (UAE) was studied in detail with the aim to: 1) provide reliable analogs for understanding and interpreting the depositional environment of ancient shallow-marine sediments from the UAE; 2) assess any modifications in the distribution of benthic environments and sedimentary facies in an area affected by significant anthropogenic activities - particular construction and land reclamation. A total of 100 sea-floor sediment samples were collected in different shallow-marine sedimentary environments (nearshore shelf, beach-front, channels, ooid shoals, lagoon and mangals) close to the coastline of Abu Dhabi Island. Where possible, we revisited the sampling sites used in several studies conducted in the middle of last century (prior to any significant anthropogenic activities) to assess temporal changes in Recent benthic foraminifera and sedimentary facies distribution during the last 50 years. Five foraminiferal assemblages were recognized in the studied area. Species with a porcellaneous test mainly belonging to the genera Quinqueloculina, Triloculina, Spiroloculina, Sigmoilinita are common in all studied areas. Larger benthic foraminifera Peneroplis and Spirolina are particularly abundant in samples collected on seaweed. Hyaline foraminifera mostly belonging to the genera Elphidium, Ammonia, Bolivina and Rosalina are also common together with Miliolidae in the nearshore shelf and beach front. Agglutinated foraminifera (Clavulina, Textularia, Ammobaculites and Reophax) are present in low percentages. The species belonging to the genera Ammobaculites and Reophax are present only in the finest grain samples particularly in lagoons and mangal environments and have not been reported previously in the studied area. The majority of the ooid shoal sediments, the coarser sediments of the beach-front and samples collected in dredged channels

  8. Oxygen respiration rates of benthic foraminifera as measured with oxygen microsensors

    DEFF Research Database (Denmark)

    Geslin, E.; Risgaard-Petersen, N.; Lombard, Fabien;

    2011-01-01

    of the foraminiferal specimens. The results show a wide range of oxygen respiration rates for the different species (from 0.09 to 5.27 nl cell−1 h−1) and a clear correlation with foraminiferal biovolume showed by the power law relationship: R = 3.98 10−3 BioVol0.88 where the oxygen respiration rate......Oxygen respiration rates of benthic foraminifera are still badly known, mainly because they are difficult to measure. Oxygen respiration rates of seventeen species of benthic foraminifera were measured using microelectrodes and calculated on the basis of the oxygen fluxes measured in the vicinity...... other microbenthos groups (nematodes, copepods, ostracods, ciliates and flagellates) suggests that benthic foraminifera have a lower oxygen respiration rates per unit biovolume. The total contribution of benthic foraminifera to the aerobic mineralisation of organic matter is estimated for the studied...

  9. 城市溪流中径流式低坝对底栖动物群落结构的影响%The impact of run-of stream dams on benthic macroinvertebrate assemblages in urban streams

    Institute of Scientific and Technical Information of China (English)

    韩鸣花; 于海燕; 周斌; 张勇; 王备新

    2012-01-01

    Study of the degradation of urban stream ecosystems has been an important focus of urban ecology. During urbanization, infrastructure such as dams and other water projects can have a significant impact on the stream ecosystem. Dams create barriers, upstream and downstream, which hinder the migration of benthic invertebrates, change their living environment and affect their reproductive success, negatively affecting the macroinvertebrate community and its structure. This destroys the integrity of the stream ecosystem. To date, there has been no published research on this topic in China. Therefore, we surveyed the macroinvertebrate assemblages of nine sites (six in urban streams with run-of stream dams [ 2- 3m] and three in reference forest streams) in August, in Xitiao River catchment, Anji County, Zhejiang Province. Using the data collected, we explored the biological degradation of urban streams and the impact of run-of stream dams on the structure and composition of the macroinvertebrate community as well as on a range of biochemical parameters. Multiple comparison and non-parametric tests were used to compare the biochemical parameters of the different stream types, performed using SPSS 18.0 statistical software. Non-metric multidimensional scaling (NMDS) analysis was used to compare the community composition, performed using Primer 6.0 software. Our results showed that the main substrate components of the reference sites were boulders (35.92% ) and cobbles (33.66% ) , while the substrate of the urban streams was mostlygravel (57.97% ). Water temperature, conductivity, and concentrations of total nitrogen and total phosphorous were all significantly ( P < 0. 05) higher in urban streams than in reference streams, whereas total taxa richness and EPT ( Ephemeroptera, Plecoptera and Trichoplera) taxa richness were significantly (P<0.05) lower in the urban streams than in the reference streams. Differences in velocity (P=0.273) and depth/width (/* = 3.92) between

  10. Tolerance of benthic foraminifera to anthropogenic stressors from three sites of the Egyptian coasts

    OpenAIRE

    Amani Badawi; Wafaa El-Menhawey

    2016-01-01

    Surely the coupling of natural and anthropogenic stressors combined with a lack of regulation resulted in the current threat to a large part of coastal marine biodiversity as well as coastal human societies, particularly in highly populated regions. The distribution pattern of benthic foraminifera as sensitive bio-indicator is utilized to assess human-induced impact on the coastal area, at Alexandria, Port Said and Suez cites of Egypt. Twenty-two benthic foraminiferal genera were identified a...

  11. Benthic Cover

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic cover (habitat) maps are derived from aerial imagery, underwater photos, acoustic surveys, and data gathered from sediment samples. Shallow to...

  12. A model for planktic foraminiferal shell growth

    OpenAIRE

    Signes, M.; Bijma, Jelle; Hemleben, C.; Ott, R.

    1993-01-01

    In this paper we analyze the laws of growth that control planktic foraminiferal shell morpholoy. We assume that isometry is the key towards the understanding of their ontogeny. Hence, our "null hypothesis" is that these organisms construct isometric shells. To test this hypothesis, geometric models of their shells have been generated with a personal computer. It is demonstrated that early chambers in log-spirally coiled structures can not follow a strict isometric arrangement. In the real wor...

  13. 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.'

  14. Benthic macrofauna

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A.; Sivadas, S.; Ingole, B.S.

    in these waters has been empirically defined as animals retained by 0.5mm screens. Many organ- isms can thus be seen only on close inspection, while other may weigh several grams while fresh. Benthic macrofauna are good indicators of estuarine conditions because... they are relatively sedentary at the sediment?water interface and within deeper sediments (Dauer and Conner 1980). The abundance of benthic animals in an area is closely related to its environment and reflects the characteristics of an ecological niche (Ansari et al...

  15. Multi-Scalar Land Cover Influences on Benthic Invertebrate Assemblages in Agricultural Streams. F.B. Daniel, M.B. Griffith, M.E. Troyer, and J.E. Lazorchak Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH 45268

    Science.gov (United States)

    Daniel, F. B.; Griffith, M. B.; Troyer, M. E.; Lazorchak, J. E.

    2005-05-01

    The northern half of the Little Miami River watershed (LMRW) was graded by the Wisconsinan glacier; the southern half lies beyond the glacier terminus and is set in an older, Illinoisan landscape. Benthic invertebrates were collected in 35 headwater streams (sub-watersheds) in the LMRW for four consecutive years and the land cover was quantified at three spatial scales (the catchment, the riparian corridor, and sampled reach) for each sub-watershed. In the northern sub-watersheds (N=19) a significantly greater percentage of land surface is committed to row crop agriculture and significantly lesser percent is covered in permanent grasses or forest relative to those in the south (N=16). Analysis of the invertebrate samples showed that Ephemeroptera, Plecoptera, and Trichoptera (EPT) constituted a significantly greater proportion of those assemblages collected from the southern sub-watersheds compared to those from the northern section In contrast, Coleoptera (Cole) and Odonata (Odon) were significantly increased in the northern streams. Approximately 60 % of the variation in the invertebrate assemblages, e.g., the ratio of EPT/(EPT+Cole+Odon), at these sites can be accounted for by consideration of land cover at either the catchment or riparian scale but not at the reach scale.

  16. Dinoflagellate cysts and benthic foraminifera in surface sediments from the Mar Piccolo in Taranto (Ionian Sea, Southern Italy)

    Science.gov (United States)

    Ferraro, L.; Rubino, F.; Frontalini, F.; Belmonte, M.; Di Leo, A.; Giandomenico, S.; Greco, M.; Lirer, F.; Spada, L.; Vallefuoco, M.

    2012-12-01

    characteristic, cysts constitute a reservoir of potential biodiversity but can also be useful indicators of productivity, eutrophication and pollution in recent marine environments. In this way, the sampling sediments of a coastal marine area, allows to monitor the responses of both microplankton and microbenthos to possible disturbance events of the ecosystem. A preliminary study, preparatory to a more detailed sampling survey during winter 2013, was carried out in December 2011 in the Mar Piccolo of Taranto (Ionian Sea), on surface sediment samples which were analyzed to identify living benthic foraminiferal assemblages and dormant stages of plankton in order to establish the potentiality of these organisms as bio-indicators of environmental stress conditions.

  17. Ecological response of benthic foraminifera to the acid drainage from mine areas. An example from the Gromolo torrent mouth (Eastern Ligurian Sea, Italy)

    Science.gov (United States)

    Bergamin, Luisa; Capello, Marco; Carbone, Cristina; Magno, Maria Celia; Consani, Sirio; Cutroneo, Laura; Ferraro, Luciana; Pierfranceschi, Giancarlo; Romano, Elena

    2016-04-01

    Benthic foraminiferal assemblages react in short time to natural and anthropogenic environmental changes and, for this, they are considered as reliable indicators of environmental quality. An interesting application of these indicators is the study of their response to environmental changes in coastal marine areas, affected by dismissed mines and dump areas. The Libiola Fe-Cu sulphide mine was intensively exploited in 19th and 20th centuries, and the activity ended in 1962. The sulphide mineral assemblages consist of pyrite and chalcopyrite, with minor sphalerite and pyrrhotite, in a gangue of quartz and chlorite. The sulphide ore occurs within the Jurassic ophiolites of the Northern Apennines which were subjected to metamorphic and tectonic processes during the subsequent Apennine orogenesis. Waters circulating in the Libiola mine area, and discharging in the adjacent streams and creeks, are strongly polluted due to the diffuse occurrence of Acid Mine Drainage processes. The Gromolo torrent collects these acidic waters enriched of heavy metals which flow into Ligurian Sea. The study area is characterised by a shelf with a gentle slope, mainly constituted by sediment supplied by Entella torrent. The general circulation has trend from East to West and the coastal drift is generally eastwards. A total of 15 marine sediment samples (upper 2 cm) were collected by means of Van Veen grab in the coastal zone close to the Gromolo mouth and analyzed for living (rose Bengal stained) and dead benthic foraminifera, together with grain size, metals and trace elements, and metal fractioning. Quantitative foraminiferal parameters, like as abundance, species diversity, heterogeneity and assemblage composition, were determined and evaluated for environmental purpose. Additionally, possible increase above the natural background level of deformed specimens was considered as indicative of metal contamination. The grain-size analyses highlighted mainly sandy sediments, characterized by

  18. Benthic Foraminifera and Bacterial Activity as a Proxy for Environmental Characterization in Potengi Estuary, Rio Grande do Norte, Brazil

    Directory of Open Access Journals (Sweden)

    Frederico S. da Silva

    2010-01-01

    Full Text Available The aim of this study was to identify possible zonation patterns and assess the environmental impact on the Potengi River Estuary, Rio Grande do Norte State, through the distribution of benthic foraminifera associated to bacterial activity and abiotic parameters. Six sediment samples were collected from locations that presented clear signs of pollution. The environment was predominantly anaerobic and fermentation occurred at all sites. Forty-two species of foraminifera were identified. The dominant species were Ammonia tepida and Arenoparrella mexicana, which are known to be opportunistic, and able to adapt to rapidly changing conditions. CCA analyses showed that salinity and organic matter, followed by bacterial carbon, were more strongly linked to organism distribution in the Potengi River Estuary. Dissolved oxygen concentration, temperature and total organic matter were higher at the estuary mouth than at the other sites, creating favorable conditions for foraminiferal growth and allowing the faunistic succession on the upper estuary. As foraminifera assemblages when associated to environmental parameters can be used as efficient proxies for environmental diagnosis, these results suggest that the Potengi Estuary is under great stress from the surrounding urban development.

  19. Benthic foraminifera

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.; Nigam, R.

    Paula, Goa, India (For Correspondence: rsaraswat@nio.org) (Modified after Paul Loubre# and William Austin$) # Department of Geology and Environmental Geosciences, Davis Hall, Northern Illinois University, DeKalb, Illinois 60115 USA $ School... and trochospiral forms) (Figure 1). The external surface of the shell is often ornamented with pits, ribs, spines, plates, etc. The benthic foraminifers communicate with the surrounding environment through an opening in the shell, called as aperture. A web...

  20. Variation on Foraminiferal Composition in Cretaceous Black-Gray-Red Bed Sequence of Southern Tibet, China

    Institute of Scientific and Technical Information of China (English)

    Wan Xiaoqiao; Si Jialiang

    2004-01-01

    An Upper Cretaceous black-gray-red bed sequence was deposited in the Tethys-Himalayan Sea where abundant foraminifera,especially planktons,were yielded. In the shallow shelf to the upper slope on the north margin of Indian plate was recorded an extinction-recovery-radiation cycle of foraminiferal fauna highly sensitive to paleoceanographical changes. The black unit, consisting of the Late Cenomanian-earliest Turonian beds, displays a major extinction, with keeled planktonic and many benthic species as the principal victims at the end of the Cenomanian when existed only low diversity, surface water-dwelling foraminifera. The gray unit spans a long-term recovery interval from the Turonian to the early Santonian with keeled planktonic foraminifera returning stepwise to the water column. The planktonic biota in the red unit, extremely abundant, indicate a biotic radiation during the Late Santonian and the Early Campanian, implying that the high oxygen levels had returned to all the oceanic depth levels, and that the water stratification disappeared, followed by the radiation of all depth-dwellers. The variation on foraminiferal faunas from the whole sequence refers to the extreme warm climate that appeared in the Middle Cretaceous and to the declined temperature toward the late epoch. Substantial deposits for this warming and cooling zones represent the black shales in the Middle Cretaceous and the red beds in the later period of the southern Tibet. The change in the foraminiferal composition corresponded to the formation of dysaerobic facies and to the development of high-oxidized circumstances.

  1. Time-Frequency Variations of Plio-Pleistocene Foraminiferal Isotopes:A Case Study from Southern South China Sea

    Institute of Scientific and Technical Information of China (English)

    Tian Jun; Wang Pinxian; Cheng Xinrong

    2004-01-01

    The continuous wavelet transform (CWT) analysis reveals the instantaneous variability of the foraminiferal δ18O and δ13C of Site 1143 for the past 5 Ma at the eccentricity, obliquity and precession bands. The cross CWT analysis further demonstrates nonstationary phases of the benthic -δ18O relative to ETP at the three primary Milankovitch bands in the last 5 Ma. The instantaneous phases between benthic -δ18O and δ13C at the precession band display a prominent 128 ka period, probably the cyclicity of the nonstationary climate close to the eccentricity. To explain these nonstationary phases, it is desirable to introduce a nonlinear response model to the global climate system, in which the output has a prominent cycle around 100 ka to match the 128 ka cycle of the instantaneous phase of the δ13C and -δ18O on the precession band.

  2. Carbon and Nitrogen Uptake of Calcareous Benthic Foraminifera along a Depth-Related Oxygen Gradient in the OMZ of the Arabian Sea.

    Science.gov (United States)

    Enge, Annekatrin J; Wukovits, Julia; Wanek, Wolfgang; Watzka, Margarete; Witte, Ursula F M; Hunter, William R; Heinz, Petra

    2016-01-01

    Foraminifera are an important faunal element of the benthos in oxygen-depleted settings such as Oxygen Minimum Zones (OMZs) where they can play a relevant role in the processing of phytodetritus. We investigated the uptake of phytodetritus (labeled with (13)C and (15)N) by calcareous foraminifera in the 0-1 cm sediment horizon under different oxygen concentrations within the OMZ in the eastern Arabian Sea. The in situ tracer experiments were carried out along a depth transect on the Indian margin over a period of 4 to 10 days. The uptake of phytodetrital carbon within 4 days by all investigated species shows that phytodetritus is a relevant food source for foraminifera in OMZ sediments. The decrease of total carbon uptake from 540 to 1100 m suggests a higher demand for carbon by species in the low-oxygen core region of the OMZ or less food competition with macrofauna. Especially Uvigerinids showed high uptake of phytodetrital carbon at the lowest oxygenated site. Variation in the ratio of phytodetrital carbon to nitrogen between species and sites indicates that foraminiferal carbon and nitrogen use can be decoupled and different nutritional demands are found between species. Lower ratio of phytodetrital carbon and nitrogen at 540 m could hint for greater demand or storage of food-based nitrogen, ingestion, or hosting of bacteria under almost anoxic conditions. Shifts in the foraminiferal assemblage structure (controlled by oxygen or food availability) and in the presence of other benthic organisms are likely to account for observed changes in the processing of phytodetritus in the different OMZ habitats. Foraminifera dominate the short-term processing of phytodetritus in the OMZ core but are less important in the lower OMZ boundary region of the Indian margin as biological interactions and species distribution of foraminifera change with depth and oxygen levels. PMID:26903959

  3. MIDDLE EOCENE TO EARLY MIOCENE FORAMINIFERAL BIOSTRATIGRAPHY IN THE EPILIGURIAN SUCCESSION (NORTHERN APENNINES, ITALY

    Directory of Open Access Journals (Sweden)

    NICOLETTA MANCIN

    2001-11-01

    Full Text Available A quantitative biostratigraphical study was performed on the foraminiferal assemblages from 15 stratigraphic sections of the Epiligurian Succession (Middle Eocene-Early Miocene, Northern Apennines, Italy. This study enabled us to identify the presence of some of the standard bioevents and to note that other bioevents are absent or show a different chronostratigraphic range. Other additional bioevents, identified throughout the area, have therefore been utilised to improve the biostratigraphical resolution of the Epiligurian sediments. These bioevents include the massive extinction of the muricate species at the Bartonian/Priabonian boundary; the increasing abundance of Paragloborotalia opima opima near Subzone P21a/P21b and the Rupelian/Chattian boundaries; and the FO of Globoquadrina dehiscens at the Subzone N4a/N4b boundary. 

  4. Response of benthic foraminifera to phytodetritus in the eastern Arabian Sea under low oxygen conditions

    Science.gov (United States)

    Enge, Annekatrin; Wukovits, Julia; Wanek, Wolfgang; Watzka, Margarete; Witte, Ursula; Hunter, William; Heinz, Petra

    2016-04-01

    At water depths between 100 and 1500 m a permanent Oxygen Minimum Zone (OMZ) impinges on the sea floor in the eastern Arabian Sea, exposing benthic organisms to anoxic to suboxic conditions. The flux of organic matter to the sea floor is relatively high at these depths but displays seasonal variation. Deposition of relatively fresh phytodetrital material (phytoplankton remains) can occur within a short period of time after monsoon periods. Several organism groups including foraminifera are involved to different extent in the processing of phytodetritus in the OMZs of the northern Arabian Sea. A series of in situ feeding experiments were performed to study the short-term processing (days) of organic carbon, nitrogen and nutritional demands of foraminifera at different oxygen concentrations on the continental margin in the eastern Arabian Sea. For the experiments, a single pulse of isotopically labeled phytodetritus was added to the sediment along a depth transect (540-1100 m) on the Indian Margin, covering the OMZ core and the lower OMZ boundary region. Uptake of phytodetritus within 4 days shows the relevance of phytodetritus as food source for foraminifera. Lower content of phytodetrital carbon recorded in foraminifera from more oxygenated depths shows greater food uptake by foraminifera in the OMZ core than in the OMZ boundary region. The foraminiferal assemblage living under almost anoxic conditions in the OMZ core is dominated by species typically found in eutroph environments (such as Uvigerinids) that are adapted to high flux of organic matter. The elevated carbon uptake can also result from missing food competition by macrofauna or from greater energy demand in foraminifera to sustain metabolic processes under hypoxic stress. Variable levels and ratios of phytodetrital carbon and nitrogen indicate specific nutritional demands and storage of food-derived nitrogen in some foraminifera species under near anoxia where the mean phytodetrital nitrogen content in

  5. Planktonic foraminiferal biogeography in the Indian sector of the Southern Ocean: Contribution from CPR data

    Science.gov (United States)

    Meilland, Julie; Fabri-Ruiz, Salomé; Koubbi, Philippe; Monaco, Claire Lo; Cotte, Cédric; Hosie, Graham W.; Sanchez, Sophie; Howa, Hélène

    2016-04-01

    production is not a suitable resource for planktonic Foraminifera. Consequently, LPF regional distribution in the upper mixed layer cannot be directly reconstructed from Chl-a concentration maps derived from satellite imagery. Knowledge of phytoplankton community composition is needed to understand the impact of primary production on foraminiferal population dynamics. Our results also emphasize that the polar/subpolar foraminiferal assemblages are characterized by high abundances of G. uvula in the iron-enriched waters surrounding the French Sub-Antarctic Islands. This species might react either to coastal or late summer production in high latitudes.

  6. 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...

  7. Non-destructive foraminiferal paleoclimatic proxies: A brief insight

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.

    Non-Destructive Foraminiferal Paleoclimatic Proxies: A Brief Insight The knowledge of past climate can help us to understand imminent climatic changes. Oceans are the vast archives of past climate. Various indirect techniques termed as proxies...

  8. Patrones de distribución espacial de ensambles de macroinvertebrados bentónicos de un sistema fluvial Andino Patagónico Spatial distribution patterns of benthic macroinvertebrates assemblages in an Andean Patagonian fluvial system

    Directory of Open Access Journals (Sweden)

    CAROLINA MOYA

    2009-01-01

    Full Text Available En enero de 2006 se estudiaron los patrones espaciales de distribución de comunidades de macroinvertebrados bentónicos de la cuenca hidrográfica del río Baker (45°50' O y 47°55' S y los principales factores controladores, intentando cubrir la mayor variedad de ecosistemas lóticos. Para llevar a cabo el estudio se seleccionaron 27 estaciones de muestreo ubicadas en las diferentes subcuencas del río. En cada estación se realizó una caracterización fisicoquímica del agua (conductividad, oxígeno disuelto, pH, temperatura y turbidez, y se documentaron las características del tramo de río (e.g. ancho del cauce y tipo de sedimento e información cartográfica utilizando un sistema de información geográfica (SIG. Se identificaron un total de 51 taxa que correspondieron en su mayoría a larvas de insectos (80 %. Los grupos con mayor riqueza fueron los órdenes Ephemeroptera (15 taxa, Plecoptera (8 taxa y Trichoptera (8 taxa. Los análisis de clasificación y ordenación realizados con los datos de abundancia, permitieron reconocer siete grupos de estaciones diferentes (A-F que fueron estadísticamente significativos (P In January of 2006 we studied the distributional patterns of benthic macroinvertebrate communities of the Baker river basin (45°50' O and 47°55' S and their main controlling factors trying to cover the greater variety of the lotic ecosystems. To carry out the study, 27 sampling stations were located in the different sub basins of the river. In each station, physical-chemical parameters of the column of water were quantified (conductivity, dissolved oxygen, pH, temperature and turbidity, and documented characteristics of the segment (e.g. wide of the channel and sediment type and cartographic information using a geographic information system (GIS and complemented with cartographic information using GIS. Identified a total of 51 taxa, are mostly insect larvae (80 %. The groups most richness were orders Ephemeroptera (15

  9. CONCORDANCE OF TAXONOMIC COMPOSITION PATTERNS ACROSS MULTIPLE LAKE ASSEMBLAGES: EFFECTS OF SCALE, BODY SIZE, AND LAND USE

    Science.gov (United States)

    We assessed environmental gradients and the extent to which they induced concordant patterns of taxonomic composition among benthic macroinvertebrate, riparian bird, sedimentary diatom, fish, and pelagic zooplankton assemblages in 186 northeastern U.S.A. lakes. Human population ...

  10. Biomonitoring polluted sediments in Arctic regions - possibilities and challenges using benthic foraminifera. Case studies from northern Norway

    Science.gov (United States)

    Skirbekk, Kari; Dijkstra, Noortje; Junttila, Juho; Sternal, Beata; Pedersen, Kristine Bondo; Forwick, Matthias; Carroll, JoLynn

    2016-04-01

    Biomonitoring pollution in marine environments using benthic foraminifera assemblages have proven to be a valid method for many regions. Two important reasons for their suitability are their sensitivity to changes in the environment and their rapid response time due to short life cycles. In addition, they are preserved in the sedimentary record, allowing for baseline studies of conditions prior to introduction of contaminants. Species of benthic foraminifera that appear to tolerate polluted sediments are referred to as opportunistic species. This notion is in general used for species able to dominate environments that are too stressful for most species. The high latitude setting of the northern Norwegian coastal zone experience high seasonality and, hence, largely changing conditions throughout a year: variations in water mass domination, freshwater influence, temperature and current velocity. It is possible that an environment like this is inhibited by a higher amount of opportunistic species generally thriving under high stress conditions. This might make the use of benthic foraminifera for biomonitoring more challenging, as the faunal compositions may be a result of a complex set of processes. Consequently, large datasets are necessary in order to make reliable conclusions, which in time may be used as generalized guidelines for biomonitoring in this geographical area. Here, we present preliminary results of benthic foraminiferal assemblages from two sites in Finnmark, northern Norway, which have been exposed to pollution. The main site is Repparfjorden, where the inner parts of the fjord were used as a submarine waste deposal site for mine tailings from a local copper mine during the 1970´s. Results from four marine sediment cores (10-20 cm long) containing sediments classified to be in moderate to very bad state (according to Norwegian sediment quality criteria) are presented. The contamination is seen in intervals of elevated copper content dated to the 1970

  11. Structure of Benthic Communities along the Taiwan Latitudinal Gradient.

    Science.gov (United States)

    Ribas-Deulofeu, Lauriane; Denis, Vianney; De Palmas, Stéphane; Kuo, Chao-Yang; Hsieh, Hernyi Justin; Chen, Chaolun Allen

    2016-01-01

    The distribution and the structure of benthic assemblages vary with latitude. However, few studies have described benthic communities along large latitudinal gradients, and patterns of variation are not fully understood. Taiwan, lying between 21.90°N and 25.30°N, is located at the center of the Philippine-Japan arc and lies at the northern margin of coral reef development. A wide range of habitats is distributed along this latitudinal gradient, from extensive fringing coral reefs at the southern coast to non-reefal communities at the north. In this study, we examined the structure of benthic communities around Taiwan, by comparing its assemblages in four regions, analyzing the effects of the latitudinal gradient, and highlighting regional characteristics. A total of 25 sites, 125 transects, and 2,625 photographs were used to analyze the benthic communities. Scleractinian corals present an obvious gradient of increasing diversity from north to south, whereas macro-algae diversity is higher on the north-eastern coast. At the country scale, Taiwanese coral communities were dominated by turf algae (49%). At the regional scale, we observed an important heterogeneity that may be caused by local disturbances and habitat degradation that smooths out regional differences. In this context, our observations highlight the importance of managing local stressors responsible for reef degradation. Overall, this study provides an important baseline upon which future changes in benthic assemblages around Taiwan can be assessed. PMID:27513665

  12. A novel salinity proxy based on Na incorporation into foraminiferal calcite

    Directory of Open Access Journals (Sweden)

    J. C. Wit

    2013-10-01

    Full Text Available Salinity and temperature determine seawater density, and differences in both thereby control global thermohaline circulation. Whereas numerous proxies have been calibrated and applied to reconstruct temperature, a direct and independent proxy for salinity is still missing. Ideally, a new proxy for salinity should target one of the direct constituents of dissolved salt, such as [Na+] or [Cl−]. This study investigates the impact of salinity on foraminiferal Na/Ca values by laser ablation ICP-MS analyses of specimens of the benthic foraminifer Ammonia tepida cultured at a range of salinities (30.0–38.6. Foraminifera at lower salinities (30.0 and 32.5 added more chambers (10–11 to their test over the course of the culturing experiment than those maintained at higher salinities (36.1, 7–8 chambers, and 38.6, 6–7 chambers, suggesting that growth rates in this species are promoted by lower salinities. The Na/Ca of cultured specimens correlates significantly with seawater salinity (Na/Ca = 0.22S–0.75, R2 = 0.96, p DNa vary between 5.17 and 9.29 mmol mol−1 and 0.12–0.16 × 10−3, which are similar to values from inorganic precipitation experiments. The significant correlation between test size and Na/Ca results from co-variation with salinity. This implies that foraminiferal Na/Ca could serve as a robust and independent proxy for salinity, enabling salinity reconstructions independent of calcitic δ18O.

  13. Biostratigraphy of Cretaceous-Paleogene marine succession, foraminiferal changes across the K/T boundary, sequence stratigraphy and response to sedimentary cyclicity in the Haymana Basin (Central Anatolia, Turkey)

    Science.gov (United States)

    Amirov, Elnur

    2016-04-01

    The aim of this study is to establish the planktonic foraminiferal biozonation, to construct the sequence stratigraphical framework and to determine the foraminiferal response to sedimentary cyclicity in the sedimentary sequence spanning Upper Cretaceous-Paleocene in the Haymana basin (Central Anatolia, Turkey). In order to achieve this study, the stratigraphic section was measured from sedimentary sequence of the Haymana, Beyobası and Yeşilyurt formations. The sedimentary sequence is mainly characterized by flyschoidal sequence that is composed of alternating of siliciclastic and carbonate units. On the account of the detailed taxonomic study of planktonic foraminifers, the biostratigraphic framework was established for the Maastrichtian-Paleocene interval. The biozonation includes 7 zones; Pseudoguembelina hariaensis, Pα, P1, P2, P3, P4 and P5 zones. The Cretaceous-Paleogene (K/P) boundary was delineated between the samples HEA-105 and 106. In order to construct the sequence-stratigraphical framework, the A, B, C and D-type meter-scale cycles were identified. Based on the stacking patterns of them, six depositional sequences, six third and two second order cycles were determined. Third order cycles coincide with the Global Sea Level Change Curve. On the account of the conducted petrographic analysis sandstone, mudstone, marl, limestone and muddy-limestone lithofacies were recorded in the studied samples. In order to demonstrate the response of foraminifers to cyclicity, quantitative analysis has been carried out by counting the individuals of planktonic, benthonic foraminifers and ostracods. The best response to sedimentary cyclicity was revealed from planktonic foraminifers. The average abundance of planktonic foraminifers increases in the transgressive systems tract and decreases in the highstand systems tract. Foraminifera are the most abundant marine protozoa in the benthic, epipelagic and pelagic realm. Because of the complexity and diversity of habitats

  14. Sedimentary geochemistry and foraminiferal assemblages in coral reef assessment of Abrolhos, Southwest Atlantic

    OpenAIRE

    Oliveira-Silva, P.; Barbosa, C. F.; C. M. ALMEIDA; Seoane, J. C. S.; Cordeiro, R.C.; Turcq, Bruno; Soares-Gomes, A.

    2012-01-01

    The health of the coral ecosystem at Abrolhos was evaluated using foraminifers and geochemistry. A total of 54 bottom sediment samples was collected for foraminifers, and 18 samples were collected for geochemistry by scuba divers at nine stations from different depth domains (A: 1 m

  15. Evaluation of Environmental Factors to Determine the Distribution of Functional Feeding Groups of Benthic Macroinvertebrates Using an Artificial Neural Network

    NARCIS (Netherlands)

    Verdonschot, P.F.M.

    2008-01-01

    Functional feeding groups (FFGs) of benthic macroinvertebrates are guilds of invertebrate taxa that obtain food in similar ways, regardless of their taxonomic affinities. They can represent a heterogeneous assemblage of benthic fauna and may indicate disturbances of their habitats. The proportion of

  16. Can benthic foraminiferal morpho-groups be used as indicators of paleomonsoonal precipitation?

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Khare, N.; Borole, D.V.

    A technique is proposed for the quick and easy assessment of paleomonsoonal precipitation through the study of morphological groups of foraminifera in a shallow water (20 m water depth) sediment core collected off Karwar, near Kali river mouth...

  17. Distributional pattern of benthic foraminiferal morpho-groups in the shelf region off Mangalore: Environmental implications

    Digital Repository Service at National Institute of Oceanography (India)

    Khare, N.; Sinha, R.; Rai, A.K.; Nigam, R.

    , the population was further placed into two broad morpho-groups namely, angular-asymmetrical and rounded-symmetrical. The surficial distribution of these groups revealed that angular-asymmetrical forms are abundant in relatively deeper region whereas rounded...

  18. Denitrification, nitrate turnover, and aerobic respiration by benthic foraminiferans in the oxygen minimum zone off Chile

    DEFF Research Database (Denmark)

    Høgslund, Signe; Revsbech, Niels Peter; Cedhagen, Tomas;

    2008-01-01

    Population density, nitrate turnover, and oxygen respiration of benthic foraminiferans were investigated in the oxygen minimum zone (OMZ) off the Chilean coast. Live foraminiferans were found predominantly in the upper 3 mm of the sediment, and the nitrate accumulating species Nonionella cf. stella...... and Stainforthia sp. dominated with a combined standing stock of 2.0 × 106 Rose Bengal stained specimens m−2. The rate of denitrification in cells of N. cf. stella analyzed with nitrous oxide microsensors during acetylene inhibition was 84 ± 33 pmol C individual−1 d−1. Multiplied with the standing...... stock of N. cf. stella and Stainforthia sp. this yielded a minimum benthic denitrification rate of 173 μmol N m−2 d−1 by foraminiferans. Foraminiferal denitrification, which seemed to account for almost all benthic denitrification at the investigated site will be overlooked by most conventional methods...

  19. 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...

  20. The role of bio-hydrodynamic interactions in determining the functioning of shallow, benthic ecosystems

    OpenAIRE

    Morris, Edward P; Peralta, Gloria; Brun, Fernando G.; Bouma, Tjeerd J.; Hendriks, Iris E; Benavente, Javier; Lara, Miguel; González-Ortiz, Vanesa; Van Engeland, Tom; Van Duren, Luca A.; Perez-Llorens, J. Lucas

    2011-01-01

    Epi-benthic organisms play a strong role in controlling pelagic-benthic mass transfer rates by directly modifying concentration gradients (i.e., production, or removal of material) and by indirectly modifying near-bed hydrodynamics. Focusing on these bio-hydrodynamic interactions, we will demonstrate how the physical structure of different assemblages, via their interaction with currents and waves, results in spatio-temporal variation in transfer rates at a range of scales. Examples will be u...

  1. The temperature and carbonate ion influence on Pleistocene high latitude planktonic foraminiferal carbon isotopic records

    Science.gov (United States)

    Charles, C.; Foreman, A. D.; Munson, J.; Slowey, N. C.; Hodell, D. A.

    2014-12-01

    Establishing a credible record of the carbon isotopic composition of high latitude surface ocean DIC over ice ages has been an enormous challenge, because the possible archives of this important variable in deep sea sediments all incorporate complex effects of the biomineralization process. For example, culture experiments (by Spero and colleagues) demonstrate a strong temperature and carbonate ion effect on the carbon isotopic composition of G. bulloides--the taxon of planktonic foraminifera that is most abundant in the majority of subpolar sediment sequences. Here we capitalize on the fortuitous observation of exceptionally strong covariation between the oxygen and carbon isotopic composition of G. bulloides in multiple sediment sequences from the Benguela upwelling region. The covariation is most clear during Marine Isotopic Stage 3 (an interval when the isotopic composition of the seawater was least variable) and undoubtedly results from the precipitation of tests under variable conditions of temperature and carbonate ion. The unusually clear isotopic relationship in planktonic foraminifera observed off Namibia constitutes a field calibration of the biomineralization effects observed in culture, and we apply it to previously published high latitude carbon isotopic records throughout the Southern Ocean. We find that many of the excursions toward lower planktonic foraminiferal δ13C that have been interpreted previously as the upwelling of nutrient rich water during deglaciations are better explained as increases in upper ocean temperature and carbonate ion. Conversely, the excursions toward high δ13C during ice age intervals that have been interpreted previously as increased export production (purportedly stimulated by dust) are also better explained by temperature and carbonate ion variability. After removal of the inferred temperature and carbonate ion signal from the planktonic foraminiferal time series, the residual is essentially (but not exactly) the same

  2. Rates of Ocean Acidification: Decoupling of Planktic and Benthic Extinctions?

    Science.gov (United States)

    Thomas, E.; Alegret, L.

    2012-12-01

    Deep-sea benthic organisms derive food from export of organic matter produced in the photic zone, so that pelagic and benthic productivity are coupled, suggesting that severe extinction of plankton and benthos in the geological past should have been coupled. An asteroid impact at the Cretaceous/Paleogene (K/Pg) boundary (~65 Ma), however, caused mass extinction of calcifying plankton (foraminifera and nannoplankton), whereas benthic calcifyers (foraminifera) did not suffer significant extinction. Also, pelagic calcifyers did not suffer severe extinction during the carbon-cycle perturbation and global warming at the Paleocene-Eocene (P/E) boundary 10 myr later, when deep-sea benthic foraminifera did. The K/Pg extinction has been interpreted as darkness-caused collapse of productivity, but this is not supported by the lack of benthic extinction. To evaluate extinction mechanisms, we compared benthic foraminiferal and stable isotope records at ODP sites in the Pacific, SE Atlantic and Southern Oceans. Across the K/Pg boundary, the decrease in export productivity was moderate, regionally variable, and insufficient to explain the mass extinction at higher levels of the food chain. Across the P/E boundary, productivity increased in epicontinental seas and on continental margins, whereas pelagic productivity may have declined (increased trophic resource continuum). We thus found no evidence that the different benthic and pelagic extinction patterns at K/Pg and P/E were linked to changes in (export) productivity. Instead, the difference between planktic and benthic extinction patterns may have been caused by the occurrence of ocean acidification at different rates. Very rapid (faster than present anthropogenic) surface ocean acidification at the K/Pg boundary may have been due to influx of impact-generated nitric acid, followed by rapid oceanic buffering. This may have been a factor in the massive extinction of pelagic calcifyers, ammonites and top-level predators such as

  3. Bathymetric preference of four major genera of rectilinear benthic foraminifera within oxygen minimum zone in Arabian Sea off central west coast of India

    Science.gov (United States)

    Mazumder, Abhijit; Nigam, Rajiv

    2014-04-01

    Fifty two surface sediment samples collected from the region off Goa, central west coast of India from water depths of 15-3300 m were analyzed with special emphasis on foraminiferal content. Rectilinear benthic foraminiferal morphogroup shows a high relative abundance within Oxygen Minimum Zone (OMZ), both shallow marine (50-60 m water depth) and intermediate to deep water (150-1500 m water depth). We gave special emphasis on four rectilinear foraminiferal genera, namely Fursenkoina, Bolivina, Bulimina and Uvigerina to observe their individual distribution among OMZ. We found genus Fursenkoina predominates at the shallow water OMZ, within the water depth zone of 50-60 m. Within 150-1500 m water depth, which is considered as intermediate to deep water OMZ in this region, genus Uvigerina shows its highest abundance above 1000 m water depth, whereas genus Bulimina shows its affinity with deeper water environment (>1000 m water depth). Genus Bolivina does not show any such depth preference, except its higher abundance in only intermediate to deep water OMZ. This depth differentiation among four rectilinear benthic foraminiferal genera presents the basic data for palaeoclimatic study based on the extent and intensity of OMZ along with the palaeobathymetry study.

  4. Bathymetric preference of four major genera of rectilinear benthic foraminifera within oxygen minimum zone in Arabian Sea off central west coast of India

    Indian Academy of Sciences (India)

    Abhijit Mazumder; Rajiv Nigam

    2014-04-01

    Fifty two surface sediment samples collected from the region off Goa, central west coast of India from water depths of 15–3300 m were analyzed with special emphasis on foraminiferal content. Rectilinear benthic foraminiferal morphogroup shows a high relative abundance within Oxygen Minimum Zone (OMZ), both shallow marine (50–60 m water depth) and intermediate to deep water (150–1500 m water depth). We gave special emphasis on four rectilinear foraminiferal genera, namely Fursenkoina, Bolivina, Bulimina and Uvigerina to observe their individual distribution among OMZ. We found genus Fursenkoina predominates at the shallow water OMZ, within the water depth zone of 50–60 m. Within 150–1500 m water depth, which is considered as intermediate to deep water OMZ in this region, genus Uvigerina shows its highest abundance above 1000 m water depth, whereas genus Bulimina shows its affinity with deeper water environment (< 1000 m water depth). Genus Bolivina does not show any such depth preference, except its higher abundance in only intermediate to deep water OMZ. This depth differentiation among four rectilinear benthic foraminiferal genera presents the basic data for palaeoclimatic study based on the extent and intensity of OMZ along with the palaeobathymetry study.

  5. 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...

  6. Environmental monitoring through protist next-generation sequencing metabarcoding: assessing the impact of fish farming on benthic foraminifera communities.

    Science.gov (United States)

    Pawlowski, Jan; Esling, Philippe; Lejzerowicz, Franck; Cedhagen, Tomas; Wilding, Thomas A

    2014-11-01

    The measurement of species diversity represents a powerful tool for assessing the impacts of human activities on marine ecosystems. Traditionally, the impact of fish farming on the coastal environment is evaluated by monitoring the dynamics of macrobenthic infaunal populations. However, taxonomic sorting and morphology-based identification of the macrobenthos demand highly trained specialists and are extremely time-consuming and costly, making it unsuitable for large-scale biomonitoring efforts involving numerous samples. Here, we propose to alleviate this laborious task by developing protist metabarcoding tools based on next-generation sequencing (NGS) of environmental DNA and RNA extracted from sediment samples. In this study, we analysed the response of benthic foraminiferal communities to the variation of environmental gradients associated with salmon farms in Scotland. We investigated the foraminiferal diversity based on ribosomal minibarcode sequences generated by the Illumina NGS technology. We compared the molecular data with morphospecies counts and with environmental gradients, including distance to cages and redox used as a proxy for sediment oxygenation. Our study revealed high variations between foraminiferal communities collected in the vicinity of fish farms and at distant locations. We found evidence for species richness decrease in impacted sites, especially visible in the RNA data. We also detected some candidate bioindicator foraminiferal species. Based on this proof-of-concept study, we conclude that NGS metabarcoding using foraminifera and other protists has potential to become a new tool for surveying the impact of aquaculture and other industrial activities in the marine environment. PMID:24734911

  7. 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...

  8. Effects of sea bass and sea bream farming (Western Mediterranean Sea on peracarid crustacean assemblages

    Directory of Open Access Journals (Sweden)

    Fernandez–Gonzalez, V.

    2011-06-01

    Full Text Available 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 variability at the two studied scales. Non-metric multi- dimensional scaling (MDS analysis showed a separation between farms and controls, indicating that peracarid assemblages are modified as a result of aquaculture activities, and some species such as Ampelisca spp. showed statistical differences. Peracarids, at both species and community level, may therefore be applied as helpful indicators to assess benthic effects of coastal farming.

  9. ICHNOTAXONOMY AND ETHOLOGY OF BORINGS IN SHALLOW-MARINE BENTHIC FORAMINIFERS FROM THE MAASTRICHTIAN AND EOCENEOF NORTHWESTERN AND SOUTHWESTERN TURKEY

    Directory of Open Access Journals (Sweden)

    JAN KRESTEN NIELSEN

    2004-07-01

    Full Text Available Larger benthic foraminiferal tests from the Maastrichtian and Eocene of western Turkey contain a large variety of borings. Two ichnospecies are defined. Maeandropolydora osmaneliensis isp. nov. in tests of Orbitoides is distinguished by a tube, winding sinuously in an irregular manner. This boring was formed by a foraging parasite or scavenger, where the tracemaker specifically exploited certain parts of its substrate. Trypanites helicus isp. nov. in tests of Nummulites is characterized by its tube coiled into a spiral. The boring is interpreted as a dwelling trace. As the boring may be considered to have both idiomorphic and stenomorphic features, it represents an ethological and taxonomic dilemma. To avoid inherent subjectivity within taxonomic classifications, we suggest the exclusion of ethological interpretations from diagnoses. The occurrence of borings may affect the preservational potential of the foraminiferal tests, and thus on the outcome of palaeoenvironmental analyses.

  10. Matching biological traits to environmental conditions in marine benthic ecosystems

    Science.gov (United States)

    Bremner, J.; Rogers, S. I.; Frid, C. L. J.

    2006-05-01

    The effects of variability in environmental conditions on species composition in benthic ecosystems are well established, but relatively little is known about how environmental variability relates to ecosystem functioning. Benthic invertebrate assemblages are heavily involved in the maintenance of ecological processes and investigation of the biological characteristics (traits) expressed in these assemblages can provide information about some aspects of functioning. The aim of this study was to establish and explore relationships between environmental variability and biological traits expressed in megafauna assemblages in two UK regions. Patterns of trait composition were matched to environmental conditions and subsets of variables best describing these patterns determined. The nature of the relationships were subsequently examined at two separate scales, both between and within the regions studied. Over the whole area, some traits related to size, longevity, reproduction, mobility, flexibility, feeding method, sociability and living habit were negatively correlated with salinity, sea surface temperature, annual temperature range and the level of fishing effort, and positively associated with fish taxon richness and shell content of the substratum. Between the two regions, reductions in temperature range and shell content were associated with infrequent relative occurrences of short-lived, moderately mobile, flexible, solitary, opportunistic, permanent-burrow dwelling fauna and those exhibiting reproductive strategies based on benthic development. Relationships between some traits and environmental conditions diverged within the two regions, with increases in fishing effort and shell content of the substratum being associated with low frequencies of occurrence of moderately mobile and moderately to highly flexible fauna within one region, but high frequencies in the other. These changes in trait composition have implications for ecosystem processes, with, for

  11. Changes in benthic ecosystems and ocean circulation in the Southeast Atlantic across Eocene Thermal Maximum 2

    Science.gov (United States)

    Jennions, S. M.; Thomas, E.; Schmidt, D. N.; Lunt, D.; Ridgwell, A.

    2015-08-01

    Eocene Thermal Maximum 2 (ETM2) occurred ~1.8 Myr after the Paleocene-Eocene Thermal Maximum (PETM) and, like the PETM, was characterized by a negative carbon isotope excursion and warming. We combined benthic foraminiferal and sedimentological records for Southeast Atlantic Sites 1263 (1500 m paleodepth) and 1262 (3600 m paleodepth) to show that benthic foraminiferal diversity and accumulation rates declined more precipitously and severely at the shallower site during peak ETM2. As the sites are in close proximity, differences in surface productivity cannot have caused this differential effect. Instead, we infer that changes in ocean circulation across ETM2 may have produced more pronounced warming at intermediate depths (Site 1263). The effects of warming include increased metabolic rates, a decrease in effective food supply and increased deoxygenation, thus potentially explaining the more severe benthic impacts at Site 1263. In response, bioturbation may have decreased more at Site 1263 than at Site 1262, differentially affecting bulk carbonate records. We use a sediment-enabled Earth system model to test whether a reduction in bioturbation and/or the likely reduced carbonate saturation of more poorly ventilated waters can explain the more extreme excursion in bulk δ13C and sharper transition in wt % CaCO3 at Site 1263. We find that both enhanced acidification and reduced bioturbation during the ETM2 peak are needed to account for the observed features. Our combined ecological and modeling analysis illustrates the potential role of ocean circulation changes in amplifying local environmental changes and driving temporary, but drastic, loss of benthic biodiversity and abundance.

  12. 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.

  13. 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...

  14. Biodiversity in Benthic Ecology

    DEFF Research Database (Denmark)

    Friberg, Nikolai; Carl, J. D.

    Foreword: This proceeding is based on a set of papers presented at the second Nordic Benthological Meeting held in Silkeborg, November 13-14, 1997. The main theme of the meeting was biodiversity in benthic ecology and the majority of contributions touch on this subject. In addition, the proceeding...

  15. 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.

  16. Land Use Influences Niche Size and the Assimilation of Resources by Benthic Macroinvertebrates in Tropical Headwater Streams

    OpenAIRE

    Parreira de Castro, Diego Marcel; Reis de Carvalho, Débora; Pompeu, Paulo dos Santos; Moreira, Marcelo Zacharias; Nardoto, Gabriela Bielefeld; Callisto, Marcos

    2016-01-01

    It is well recognized that assemblage structure of stream macroinvertebrates changes with alterations in catchment or local land use. Our objective was to understand how the trophic ecology of benthic macroinvertebrate assemblages responds to land use changes in tropical streams. We used the isotope methodology to assess how energy flow and trophic relations among macroinvertebrates were affected in environments affected by different land uses (natural cover, pasture, sugar cane plantation). ...

  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. Latest miocene benthic delta/sup 18/O changes, global ice volume, sea level and the Messinian salinity crisis

    Energy Technology Data Exchange (ETDEWEB)

    Hodell, D.A.; Elmstrom, K.M.; Kennett, J.P.

    1986-04-03

    Oxygen isotope evidence indicates high but variable delta/sup 18/O values in benthic foraminiferal calcite during the latest Miocene and earliest Pliocene. These high values may represent increases in global ice volume and associated sea-level fall. The delta/sup 18/O record resembles glacial/interglacial cycles, but with only one-third the amplitude of the late Pleistocene signal. This variability may reflect instability in the Antarctic ice sheet, and palaeomagnetic correlation points to an isotopic event coinciding with the isolation and desiccation of the Mediterranean basin during the latest Messinian.

  19. Foraminiferal fauna from the Cochin backwaters: Biological indicators of man-made changes in the environment

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, K.K.

    life as a result of deepening of the navigational channel by dredging. Navertheless, further reclamation of marshes/wetlands will have a very adverse effect on backwater habitats rich in foraminiferal fauna....

  20. Species diversity variations in Neogene deep-sea benthic foraminifera at ODP Hole 730A, western Arabian Sea

    Indian Academy of Sciences (India)

    Yuvaraja Arumugm; Anil K Gupta; Mruganka K Panigrahi

    2014-10-01

    Deep-sea benthic foraminifera are an important and widely used marine proxy to understand paleoceanographic and paleoclimatic changes on regional and global scales, owing to their sensitivity to oceanic and climatic turnovers. Some species of benthic foraminifera are sensitive to changes in water mass properties whereas others are sensitive to organic fluxes and deep-sea oxygenation. Benthic faunal diversity has been found closely linked to food web, bottom water oxygen levels, and substrate and water mass stability. The present study is aimed at analyzing species diversity trends in benthic foraminifera and their linkages with Indian monsoon variability during the Neogene. Species diversity of benthic foraminifera is examined in terms of number of species (S), information function (H), equitability (E) and Sanders’ rarefied values, which were combined with relative abundances of high and low productivity benthic foraminifera at Ocean Drilling Program Hole 730A, Oman margin, western Arabian Sea. The Oman margin offers the best opportunity to understand monsoon-driven changes in benthic diversity since summer monsoon winds have greater impact on the study area. The species diversity was higher during the early Miocene Climatic Optimum (∼17.2–16.4 Ma) followed by a decrease during 16.4–13 Ma coinciding with a major increase in Antarctic ice volume and increased formation of Antarctic Bottom Water. All the diversity parameters show an increase during 13–11.6 Ma, a gradual decrease during 11.6–9 Ma and then an increase with a maximum at 7 Ma. Thereafter the values show little change until 1.2 Ma when all the parameters abruptly decrease. The benthic foraminiferal populations and diversity at Hole 730A were mainly driven by the Indian monsoon, and polar waters might have played a minor or no role since early Neogene period as the Arabian Sea is an enclosed basin.

  1. 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...

  2. Macroalgal Extracts Induce Bacterial Assemblage Shifts and Sublethal Tissue Stress in Caribbean Corals

    OpenAIRE

    Morrow, Kathleen M.; Raphael Ritson-Williams; Cliff Ross; Mark R Liles; Paul, Valerie J

    2012-01-01

    Benthic macroalgae can be abundant on present-day coral reefs, especially where rates of herbivory are low and/or dissolved nutrients are high. This study investigated the impact of macroalgal extracts on both coral-associated bacterial assemblages and sublethal stress response of corals. Crude extracts and live algal thalli from common Caribbean macroalgae were applied onto the surface of Montastraea faveolata and Porites astreoides corals on reefs in both Florida and Belize. Denaturing grad...

  3. 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

  4. A stage 7 marine interglacial record (the Groedeland Interglacial) on Jaeren, southwestern Norway; foraminiferal, stable isotopes and amino acid evidence

    International Nuclear Information System (INIS)

    Foraminiferal stratigraphy, stable isotopes and amino-acid diagenesis have been investigated in a 125 m (+1 to - 124 m a.s.l.) long core from Jaeren, south-western Norway. Two marine units, the 42 m thick Groedeland Sand and the 8 m thick Sunde Sand, were found between till beds. Based on the bio stratigraphic data nine foraminiferal assemblage zones are defined. The Groedeland Sand shows a development from an ice-proximal glacial environment in the lower part, through an arctic, possibly shallow-water, environment, into a full interglacial open-shelf regime (the Groedeland Interglacial). The Groedeland Interglacial sediments (zone 6 Cassidulinalaevigata-Cibicides zones) were deposited at a water depth of 20 m, in an open, high-energy shelf environment with temperature conditions similar to those prevailing in the northern North Sea today. The interglacial sediments are followed by deposits characteristic of an arctic environment which become more ice proximal upwards. Superimposed on the Groedeland Sand is a diamicton interpreted as till. Above the till is the upper marine unit (the Sand Sund) which in the lower part yielded a shallow-water arctic fauna replaced upwards by an ice-proximal facies. The upper part of the Sunde Sand is barren of foraminifera and is superimposed by an upper till. The Sunde Interstadial is defined as a climatostratigraphic even resulting in deglaciation of western Norway and deposition of the Sunde Sand. Based on amino acid geochronology and inferences from the bio stratigraphy, the Groedeland Interglacial is assigned to oxygen isotope stage 7, whereas the Sunde Interstadial is assigned to the Early Weichselian. Combined with existing data from the North Sea region and the Norwegian Sea it is concluded that for stage 7, in addition stage 1 and 5e, there must have been a strong influx of Atlantic water into the Norwegian Sea north of the British Isles. This circulation created a similar north-south gradient in water masses in the North

  5. High resolution climatic records of the past ~489 years from Central Asia as derived from benthic foraminiferal species, Asterorotalia trispinosa

    Digital Repository Service at National Institute of Oceanography (India)

    Panchang, R.; Nigam, R.

    out the isotope analysis and elemental analysis. The guidance of Dr. Pravin Taware from the National Research Centre for Grapes (NRC Grapes), Indian Council for Agricultural Research (ICAR), Pune in conducting the statistical analysis used...

  6. Combining benthic foraminiferal ecology and shell Mn/Ca to deconvolve past bottom water oxygenation and paleoproductivity

    NARCIS (Netherlands)

    Koho, K.A.; de Nooijer, L.J.; Reichart, G.J.

    2015-01-01

    The Mn/Ca of carbonate tests of living deep-sea foraminifera (Hoeglundina elegans, Bulimina aculeata, Uvigerina peregrina and Melonis barleeanus) were determined together with pore water manganese along a bottom water oxygen gradient across the lower boundary of the Arabian Sea oxygen minimum zone.

  7. Can bathymetry be a discriminatory factor for the distribution of benthic foraminiferal morpho-groups in modern marine sediments?

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Khare, N.; Mayenkar, D.N.

    -symmetrical. The distribution profiles of these morpho-groups in the surface sediments apparently showed that angular-asymmetrical morpho-group is more or less abundant in deeper regions while, rounded-symmetrical morpho-group tends to flourish in relatively shallower regions...

  8. Deterioration of Early Holocene coral reef due to sea level rise along west coast of India: Benthic foraminiferal testimony

    Digital Repository Service at National Institute of Oceanography (India)

    Mazumder, A.; Nigam, R.; Henriques, P.J.

    . Marine Geology 167, 243-260. Bruckner, H., 1989. Late Quaternary shorelines in India, in: Schott, D.B., Pirazzoli, P.A., Honig, C.A. (Eds.), Late Quaternary Sea Level Correlation and Applications. Kluver, Dordrecht, pp. 169-194. Coughan, M.J., Neyenzi..., B., 1991. Climatic trends and variability, in: Jager, J., Ferguson, H.L. (Eds.), Climate change, Science, Impact and Policy. Proc. II World Climate Conference, pp. 71-82. Daniel, A., 1972. Marine intertidal barnacles in the Indian Ocean. Proceeding...

  9. 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.

  10. Living (stained) benthic foraminifera from the Mozambique Channel (eastern Africa): Exploring ecology of deep-sea unicellular meiofauna

    Science.gov (United States)

    Fontanier, C.; Garnier, E.; Brandily, C.; Dennielou, B.; Bichon, S.; Gayet, N.; Eugene, T.; Rovere, M.; Grémare, A.; Deflandre, B.

    2016-09-01

    Live (Rose-Bengal stained) deep-sea foraminiferal faunas have been studied at four stations between 530 and 3200-m depth in the Mozambique Channel (eastern Africa) to understand how complex environmental conditions (e.g., organic matter, oxygenation) control their ecological structure (i.e., diversity, density, and microhabitats). Two upper-slope stations, located at 530- and 780-m depth off Madagascar, are bathed by well-oxygenated bottom waters. They are characterized by fine sediments enriched in highly degraded organic matter (low amino-acid bio-availability and reduced chlorophyllic freshness). Mineralization of organic compounds results in relatively moderate oxygen penetration depth (i.e., 15 and 30 mm) in sediment. Interestingly, foraminiferal species richness (S) is exceptionally high at both sites. The highest densities are observed in the 780-m deep station, where peculiar sedimentary facies of organic matter are recorded (OC >2.0% DW). Redox conditions and sedimentary organic matter control the composition and the vertical distribution (i.e. microhabitat) of benthic faunas at both upper-slope sites. Bolivina alata, Bulimina marginata, Haplophragmoides bradyi and Nouria compressa are relevant bio-indicators of enhanced burial of organic matter prevailing at the 780-m deep station (i.e., eutrophic conditions), whereas Uvigerina hispida and Uvigerina semiornata are dominant at the 530-m deep station (i.e., relatively mesotrophic conditions). Two other stations are located on well-ventilated terraces from the deep-sea canyons of Tsiribihina and Zambezi (>3000-m depth). They are characterized by carbonate ooze, which is depleted in degraded organic matter and, where oxygen penetration depth is relatively deep (i.e.,>80 mm). Because of food scarcity, S and densities are relatively low, and agglutinated and organic-walled taxa dominate foraminiferal faunas. Hospitella fulva, a foraminiferal species belonging to Allogromiida, occupies very deep infaunal

  11. Doğu Pontidler’deki (KD Türkiye) Üst Maastrihtiyen- Paleosen Sığ Denizel Karbonat Istiflerinin Mikrofasiyesleri ve Bentik Foraminiferlerin Stratigrafik Dağılımı

    OpenAIRE

    İNAN, Nurdan; İnan, Selim

    2014-01-01

    This study is a synthesis and reinterpretation of our previous works on microfacies and benthic foraminiferal assemblages of the Eastern Pontides Upper Maastrichtian-Palaeocene shallow water carbonate sequences. The aim of this study is to introduce relation between stratigraphic distribution of the foraminiferal assemblages and facies. The Upper Maastrichtian-Paleocene (K/T) transition is determined by the last occurence of predominant orbitoidal forms and by the first appearance of associat...

  12. Diel variation in near-shore great lakes fish assemblages and implications for assessment sampling and coastal management

    Science.gov (United States)

    McKenna, J.E., Jr.

    2008-01-01

    I compared fish assemblages captured in three different microhabitats (shoreline, pelagic near-shore, and benthic near-shore) during day and night fishing in different protection (inside bay or tributary vs. outside in Lake Ontario proper) and turbidity regimes of four near-shore areas of Lake Ontario. The effects of diel movement and availability to gear were clearly evident. Fish assemblages were consistently and significantly more diverse at night than during the day, with nighttime assemblages often being supersets of daytime assemblages. Evidence for a turbidity effect was much weaker than the effects of nocturnal movements and changes in availability to the gear associated with darkness. Nighttime sampling is more likely to capture the full array of species in near-shore areas of the Great Lakes than daytime sampling.

  13. Spatial Variability of Benthic-Pelagic Coupling in an Estuary Ecosystem: Consequences for Microphytobenthos Resuspension Phenomenon

    Science.gov (United States)

    Ubertini, Martin; Lefebvre, Sébastien; Gangnery, Aline; Grangeré, Karine; Le Gendre, Romain; Orvain, Francis

    2012-01-01

    The high degree of physical factors in intertidal estuarine ecosystem increases material processing between benthic and pelagic compartments. In these ecosystems, microphytobenthos resuspension is a major phenomenon since its contribution to higher trophic levels can be highly significant. Understanding the sediment and associated microphytobenthos resuspension and its fate in the water column is indispensable for measuring the food available to benthic and pelagic food webs. To identify and hierarchize the physical/biological factors potentially involved in MPB resuspension, the entire intertidal area and surrounding water column of an estuarine ecosystem, the Bay des Veys, was sampled during ebb tide. A wide range of physical parameters (hydrodynamic regime, grain size of the sediment, and suspended matter) and biological parameters (flora and fauna assemblages, chlorophyll) were analyzed to characterize benthic-pelagic coupling at the bay scale. Samples were collected in two contrasted periods, spring and late summer, to assess the impact of forcing variables on benthic-pelagic coupling. A mapping approach using kriging interpolation enabled us to overlay benthic and pelagic maps of physical and biological variables, for both hydrological conditions and trophic indicators. Pelagic Chl a concentration was the best predictor explaining the suspension-feeders spatial distribution. Our results also suggest a perennial spatio-temporal structure of both benthic and pelagic compartments in the ecosystem, at least when the system is not imposed to intense wind, with MPB distribution controlled by both grain size and bathymetry. The benthic component appeared to control the pelagic one via resuspension phenomena at the scale of the bay. Co-inertia analysis showed closer benthic-pelagic coupling between the variables in spring. The higher MPB biomass observed in summer suggests a higher contribution to filter-feeders diets, indicating a higher resuspension effect in

  14. Effects of coral reef benthic primary producers on dissolved organic carbon and microbial activity.

    Directory of Open Access Journals (Sweden)

    Andreas F Haas

    Full Text Available Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates of photosynthesis, respiration, and dissolved organic carbon (DOC release were assessed for several common benthic reef organisms from the backreef habitat. We assessed microbial community response to dissolved exudates of each benthic producer by measuring bacterioplankton growth, respiration, and DOC drawdown in two-day dark dilution culture incubations. Experiments were conducted for six benthic producers: three species of macroalgae (each representing a different algal phylum: Turbinaria ornata--Ochrophyta; Amansia rhodantha--Rhodophyta; Halimeda opuntia--Chlorophyta, a mixed assemblage of turf algae, a species of crustose coralline algae (Hydrolithon reinboldii and a dominant hermatypic coral (Porites lobata. Our results show that all five types of algae, but not the coral, exuded significant amounts of labile DOC into their surrounding environment. In general, primary producers with the highest rates of photosynthesis released the most DOC and yielded the greatest bacterioplankton growth; turf algae produced nearly twice as much DOC per unit surface area than the other benthic producers (14.0±2.8 µmol h⁻¹ dm⁻², stimulating rapid bacterioplankton growth (0.044±0.002 log10 cells h⁻¹ and concomitant oxygen drawdown (0.16±0.05 µmol L⁻¹ h⁻¹ dm⁻². Our results demonstrate that benthic reef algae can release a significant fraction of their photosynthetically-fixed carbon as DOC, these release rates vary by species, and this DOC is available to and consumed by reef associated microbes. These data provide compelling evidence that benthic primary producers differentially influence

  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. National Benthic Infaunal Database (NBID)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NBID is a quantitative database on abundances of individual benthic species by sample and study region, along with other synoptically measured environmental...

  17. Benthic fauna of mangrove environment

    Digital Repository Service at National Institute of Oceanography (India)

    Parulekar, A.H.

    distribution of benthic communities in mangrove environment is governEd. by tidal amplitude, light penetration, nature of substratum and distance from the sea. The littoral zone, neritic zone, Barnacle-oyster zone, Uca zone, Polychaeta zone have been delineated...

  18. NEPR Benthic Habitat Map 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This benthic habitat map was created from a semi-automated habitat mapping process, using a combination of bathymetry, satellite imagery, aerial imagery and...

  19. Mid Pleistocene foraminiferal mass extinction coupled with phytoplankton evolution

    Science.gov (United States)

    Kender, Sev; McClymont, Erin L.; Elmore, Aurora C.; Emanuele, Dario; Leng, Melanie J.; Elderfield, Henry

    2016-06-01

    Understanding the interaction between climate and biotic evolution is crucial for deciphering the sensitivity of life. An enigmatic mass extinction occurred in the deep oceans during the Mid Pleistocene, with a loss of over 100 species (20%) of sea floor calcareous foraminifera. An evolutionarily conservative group, benthic foraminifera often comprise >50% of eukaryote biomass on the deep-ocean floor. Here we test extinction hypotheses (temperature, corrosiveness and productivity) in the Tasman Sea, using geochemistry and micropalaeontology, and find evidence from several globally distributed sites that the extinction was caused by a change in phytoplankton food source. Coccolithophore evolution may have enhanced the seasonal `bloom' nature of primary productivity and fundamentally shifted it towards a more intra-annually variable state at ~0.8 Ma. Our results highlight intra-annual variability as a potential new consideration for Mid Pleistocene global biogeochemical climate models, and imply that deep-sea biota may be sensitive to future changes in productivity.

  20. Biodiversity loss in benthic macroinfaunal communities and its consequence for organic mercury trophic availability to benthivorous predators in the lower Hudson River estuary, USA

    International Nuclear Information System (INIS)

    Organic mercury such as methylmercury is not only one of the most toxic substances found in coastal ecosystems but also has high trophic transfer efficiency. In this study, we examined implications of chronically altered benthic macroinfaunal assemblages for organic mercury trophic availability (based on organic mercury intracellular partitioning) to their predators in the Arthur Kill-AK (New York, USA). Despite low species diversity, both density and biomass of benthic macroinvertebrates in AK were significantly higher than those at the reference site. Disproportionately high biomass of benthic macroinvertebrates (mostly polychaetes) in the northern AK resulted in a more than twofold increase ('ecological enrichment') in the trophically available organic mercury pool. These results suggest that altered benthic macroinfaunal community structure in AK may play an important role in organic mercury trophic availability at the base of benthic food webs and potentially in mercury biogeochemical cycling in this severely urbanized coastal ecosystem.

  1. 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.

  2. 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...

  3. Mid Pleistocene foraminiferal mass extinction coupled with phytoplankton evolution.

    Science.gov (United States)

    Kender, Sev; McClymont, Erin L; Elmore, Aurora C; Emanuele, Dario; Leng, Melanie J; Elderfield, Henry

    2016-01-01

    Understanding the interaction between climate and biotic evolution is crucial for deciphering the sensitivity of life. An enigmatic mass extinction occurred in the deep oceans during the Mid Pleistocene, with a loss of over 100 species (20%) of sea floor calcareous foraminifera. An evolutionarily conservative group, benthic foraminifera often comprise >50% of eukaryote biomass on the deep-ocean floor. Here we test extinction hypotheses (temperature, corrosiveness and productivity) in the Tasman Sea, using geochemistry and micropalaeontology, and find evidence from several globally distributed sites that the extinction was caused by a change in phytoplankton food source. Coccolithophore evolution may have enhanced the seasonal 'bloom' nature of primary productivity and fundamentally shifted it towards a more intra-annually variable state at ∼0.8 Ma. Our results highlight intra-annual variability as a potential new consideration for Mid Pleistocene global biogeochemical climate models, and imply that deep-sea biota may be sensitive to future changes in productivity. PMID:27311937

  4. 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

  5. Benthic foraminifera at the Cretaceous-Tertiary boundary around the Gulf of Mexico

    Science.gov (United States)

    Alegret, Laia; Molina, Eustoquio; Thomas, Ellen

    2001-10-01

    Cretaceous-Tertiary (K-T) boundary sections in northeastern Mexico contain marly formations separated by a controversial clastic unit. Benthic foraminifera in seven sections indicate middle and lower bathyal depths of deposition for the marls, with the exception of the upper bathyal northernmost section. Mixed neritic-bathyal faunas were present in the clastic unit, indicating redeposition in the deep basin by mass-wasting processes resulting from the K-T bolide impact in the Gulf of Mexico. Benthic foraminifera in the Mexican sections, and at other deep-sea locations, were not subject to major extinction at the time of impact, but there were temporary changes in assemblage composition. Benthic faunas indicate well- oxygenated bottom waters and mesotrophic conditions during the late Maastrichtian and increased food supply during the latest Maastrichtian. The food supply decreased drastically just after the K-T boundary, possibly because of the collapse of surface productivity. Cretaceous and early Paleogene benthic foraminifera, however, did not exhibit the benthic-pelagic coupling of present-day faunas, as documented by the lack of significant extinction at the K-T collapse of surface productivity. Much of the food supplied to the benthic faunas along this continental margin might have been refractory material transported from land or shallow coastal regions. The decrease in food supply at the K-T boundary might be associated with the processes of mass wasting, which removed surface, food-rich sediment. Benthic faunas show a staggered pattern of faunal recovery in the lowermost Paleogene, consistent with a staged recovery of the vertical organic flux but also with a gradual buildup of organic matter in the sediment.

  6. A multivariate statistical study with a factor analysis of recent planktonic foraminiferal distribution in the Coromandel Coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Jayalakshmy, K.V.; Rao, K.K.

    , 17 foraminiferal species, species were clustered into 5 groups with row normalisation and varimax rotation for Q-mode factor analysis. The 19 stations were also grouped into 5 groups with only 2 groups statistically significant using column...

  7. Seasonal variations in planktonic foraminiferal flux and oxygen isotopic composition in the western North Pacific : Implications for paleoceanographic reconstruction

    OpenAIRE

    Sagawa, Takuya; Kuroyanagi, Azumi; Irino, Tomohisa; Kuwae, Michinobu; Kawahata, Hodaka

    2013-01-01

    The oxygen isotopic composition (delta O-18) of planktonic foraminiferal shells in seafloor sediment provides information on past surface oceanography. Knowledge of seasonal and depth habitat, as well as the delta O-18 disequilibrium (vital effect), is essential to constrain the interpretation of sedimentary delta O-18. Here, we present a 1-year time series of planktonic foraminiferal shell fluxes and delta(18)Ofrom a sediment trap moored in the northwestern margin of the North Pacific. The v...

  8. Tolerance of benthic foraminifera to anthropogenic stressors from three sites of the Egyptian coasts

    Directory of Open Access Journals (Sweden)

    Amani Badawi

    2016-03-01

    Full Text Available Surely the coupling of natural and anthropogenic stressors combined with a lack of regulation resulted in the current threat to a large part of coastal marine biodiversity as well as coastal human societies, particularly in highly populated regions. The distribution pattern of benthic foraminifera as sensitive bio-indicator is utilized to assess human-induced impact on the coastal area, at Alexandria, Port Said and Suez cites of Egypt. Twenty-two benthic foraminiferal genera were identified and complied by principal component analysis into four factors through cluster analysis. Cross correlation of the generic composition, distribution and relative abundance of common genera in the three investigated cores revealed three different coastal environments entities. The categorized environment ranged from light human impact as Alexandria site to heavily impacted by human activities as Port Said and Suez sites. Fauna of Alexandria site reflects an increase in un-polluted water activity revealing high-energy erosive environment. The second entity involves Port Said site, which represents a highly stressed coastal environment, corresponding to high-energy transport conditions influenced by fresh water flush from local Manzala Lake via Bougaz El Gamel outlet while Suez site is influenced by marine hypersaline water coupling with intensified levels of industrial and domestic pollution, attributed to the anthropogenic impact.

  9. Disturbance frequency influences patch dynamics in stream benthic algal communities.

    Science.gov (United States)

    Ledger, Mark E; Harris, Rebecca M L; Armitage, Patrick D; Milner, Alexander M

    2008-04-01

    Disturbance is integral to the organisation of riverine ecosystems. Fluctuating low flows caused by supra-seasonal drought and water management periodically dewater habitat patches, potentially creating heterogeneity in the taxonomic composition and successional dynamics of benthic communities. The frequency of disturbance induced by low flows is contingent upon the topography of the river bed and thus varies among patches. We investigated whether the frequency of patch dewatering influenced the structure and temporal dynamics of benthic algal communities attached to the upper surfaces of stones in stream mesocosms (4 m2). In a 693-day disturbance experiment, we applied short dewatering disturbances (6 days) at high (33-day cycles) and low frequencies (99-day cycles) and compared algal assemblages with undisturbed controls at 21 endpoints. In the absence of disturbance, epilithic space was dominated by the green encrusting alga Gongrosira incrustans. However, drying disturbances consistently reduced the dominance of the green alga, and crust abundance decreased with increasing disturbance frequency, thereby opening space for a diversity of mat-forming diatoms. The response of mat diatoms to disturbance varied markedly during the experiment, from strong reductions in the abundance of loosely attached mats in mid-late 2000 to the exploitation of open space by closely adhering mats in 2001. Contrary responses were attributed to changes in the species composition of mat diatoms, which influenced the physiognomy and hence stress-resistance and resilience of the assemblage. Our results indicate that patchy dewatering of habitat patches during periods of low flow influences the successional dynamics of algae, thereby creating distinctive mosaics on the stream bed. PMID:18193289

  10. Dissolved organic carbon concentration controls benthic primary production: results from in situ chambers in north-temperate lakes

    Science.gov (United States)

    Godwin, Sean C.; Jones, Stuart E.; Weidel, Brian C.; Solomon, Christopher T.

    2014-01-01

    We evaluated several potential drivers of primary production by benthic algae (periphyton) in north-temperate lakes. We used continuous dissolved oxygen measurements from in situ benthic chambers to quantify primary production by periphyton at multiple depths across 11 lakes encompassing a broad range of dissolved organic carbon (DOC) and total phosphorous (TP) concentrations. Light-use efficiency (primary production per unit incident light) was inversely related to average light availability (% of surface light) in 7 of the 11 study lakes, indicating that benthic algal assemblages exhibit photoadaptation, likely through physiological or compositional changes. DOC alone explained 86% of the variability in log-transformed whole-lake benthic production rates. TP was not an important driver of benthic production via its effects on nutrient and light availability. This result is contrary to studies in other systems, but may be common in relatively pristine north-temperate lakes. Our simple empirical model may allow for the prediction of whole-lake benthic primary production from easily obtained measurements of DOC concentration.

  11. A New Integrated Approach to Taxonomy: The Fusion of Molecular and Morphological Systematics with Type Material in Benthic Foraminifera.

    Science.gov (United States)

    Roberts, Angela; Austin, William; Evans, Katharine; Bird, Clare; Schweizer, Magali; Darling, Kate

    2016-01-01

    A robust and consistent taxonomy underpins the use of fossil material in palaeoenvironmental research and long-term assessment of biodiversity. This study presents a new integrated taxonomic protocol for benthic foraminifera by unequivocally reconciling the traditional taxonomic name to a specific genetic type. To implement this protocol, a fragment of the small subunit ribosomal RNA (SSU rRNA) gene is used in combination with 16 quantitative morphometric variables to fully characterise the benthic foraminiferal species concept of Elphidium williamsoni Haynes, 1973. A combination of live contemporary topotypic specimens, original type specimens and specimens of genetic outliers were utilised in this study. Through a series of multivariate statistical tests we illustrate that genetically characterised topotype specimens are morphologically congruent with both the holotype and paratype specimens of E. williamsoni Haynes, 1973. We present the first clear link between morphologically characterised type material and the unique SSU rRNA genetic type of E. williamsoni. This example provides a standard framework for the benthic foraminifera which bridges the current discontinuity between molecular and morphological lines of evidence, allowing integration with the traditional Linnaean roots of nomenclature to offer a new prospect for taxonomic stability. PMID:27388271

  12. Benthic Foraminifera as ecological indicators for water quality on the Great Barrier Reef

    Science.gov (United States)

    Uthicke, Sven; Nobes, Kristie

    2008-07-01

    Benthic foraminifera are established indicators for Water Quality (WQ) in Florida and the Caribbean. However, nearshore coral reefs of the Great Barrier Reef (GBR) and other Pacific regions are also subjected to increased nutrient and sediment loads. Here, we investigate the use of benthic foraminifera as indicators to assess status and trends of WQ on GBR reefs. We quantified several sediment parameters and the foraminiferan assemblage composition on 20 reefs in four geographic regions of the GBR, and along a water column nutrient and turbidity gradient. Twenty-seven easily recognisable benthic foraminiferan taxa (>63 μm) were distinguished. All four geographic regions differed significantly ( p plastids ( Elphidium sp.) where highly characteristic for low light, higher nutrient conditions. Application of the FORAM index to GBR assemblage composition showed a significant increase in the value of this index with increased distance from the mainland in the Whitsunday region ( r2 = 0.75, p < 0.001), and therefore with increasing light and decreased nutrient availability. We conclude that it will be possible to apply this index to GBR and possibly other Pacific reefs after some adaptations and additional experimental work on species-specific limiting factors.

  13. Natural thermoluminescence of fossil foraminiferals as a potential proxy for deep-sea temperature changes

    Institute of Scientific and Technical Information of China (English)

    LIU Haisheng; FANG Nianqiao; HOU Shengli; CHEN Yexun

    2008-01-01

    Foraminiferal shells from two piston cores separately located at the Ninetyeast Ridge and the Bengal Fan of the Indian Ocean were selected and purified for measurements of natural thermoluminescence (NTL) intensity by a high precision thermoluminescence meter ( RGD-3 ).Variations of the NTL intensity along the two core sequences both spanning the last two glacial-interglacial cycles displayed a strong,identical signal of the global ice volume cycles,which matched well with their corresponding oxygen isotope data.As higher NTL intensity occurred within interglacial periods and changes in an NTL signal were most likely influ-enced by the temperature of ambient seawater in which the planktonic foraminiferal shells long existed,the NTL signal could be considered as a potential proxy for orbital scale temperature changes of bottom seawater in the tropical Indian Ocean.

  14. Effects of Cylindrospermopsin Producing Cyanobacterium and Its Crude Extracts on a Benthic Green Alga—Competition or Allelopathy?

    OpenAIRE

    Viktória B-Béres; Gábor Vasas; Dalma Dobronoki; Sándor Gonda; Sándor Alex Nagy; István Bácsi

    2015-01-01

    Cylindrospermopsin (CYN) is a toxic secondary metabolite produced by filamentous cyanobacteria which could work as an allelopathic substance, although its ecological role in cyanobacterial-algal assemblages is mostly unclear. The competition between the CYN-producing cyanobacterium Chrysosporum (Aphanizomenon) ovalisporum, and the benthic green alga Chlorococcum sp. was investigated in mixed cultures, and the effects of CYN-containing cyanobacterial crude extract on Chlorococcum sp. were test...

  15. A broad deglacial δ13C minimum event in planktonic foraminiferal records in the Okinawa Trough

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The equatorial Pacific upwelling zone has been suspected of playing an important role in the global atmospheric CO2 changes associated with glacial-interglacial cycles.In order to assess the influencing scope of the surface water deglacial δ13C minimum in the tropical Iow-latitude Pacific,the core DGKS9603, collected from the middle Okinawa Trough, was examined for δ13C records of planktonic foraminifera N. dutertrei and G. ruber. The planktonic foraminiferal δ13C records show a clear decreasing event from 20 to 6 cal. kaBP., which is characterized by long duration of about 14 ka and amplitude shift of 0.4 × 10-3. Its minimum value occurred at 15.7 cai kaBP. The event shows fairly synchrony with the surface water deglacial δ13C minimum identiffed in the tropical Pacific and its marginal seas. Because there is no evidence in planktonic foraminiferal fauna and δ18O records for upwelling and river runoff enhancement,the broad deglacial δ13C minimum event in planktonic foraminiferal records revealed in core DGKS9603 might have been the direct influencing result of the deglacial surface water of the tropical Pacific. The identification for the event in the Okinawa Trough provides new evidence that the water evolution in the tropical low-latitude Pacific plays a key role in large regional, even global carbon cycle.

  16. FORAMINIFERAL CHARACTERISATION OF MID-UPPER JURASSIC SEQUENCES IN THE WESSEX BASIN (UNITED KINGDOM

    Directory of Open Access Journals (Sweden)

    MELISSA J. OXFORD

    2004-03-01

    Full Text Available The use of foraminifera in the characterisation of sequences (systems tracts, maximum flooding surfaces, etc. has developed over the last decade. Much of this work has been based in the Cenozoic successions of the Gulf of Mexico, although there is a growing application of such data in the Middle East and the North Sea Basin. The easiest surface to characterise has been the maximum flooding surface with its high diversity and high(er abundance faunas; the characterisation of individual systems tracts has been less successful. Using the well-known mid-Upper Jurassic successions of the Dorset coastal sections, we have investigated a number of high resolution (parasequences for their foraminiferal content. Using data of foraminiferal diversity and standing crops from a range of modern substrates we have investigated the potential faunas available after deposition, taphonomy, compaction, groundwater dissolution and modern weathering. By understanding the processes involved we have identified the key foraminiferal features of typical mid-Upper Jurassic sequences and indicated how this work may help in the correlation of successions in North Dorset and Normandy.

  17. 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...

  18. Planktic Foraminiferal Response to the "Latest Danian Event" (62.15 Ma) on an almost Global Scale - results from Shatsky Rise, Walvis Ridge and Newfoundland

    Science.gov (United States)

    Jehle, S.; Bornemann, A.; Deprez, A.; Speijer, R. P.

    2015-12-01

    The marine ecosystem of the Paleocene was disturbed by several transient warming events. One of these is the Latest Danian Event (LDE aka "Top C27n Event"). In deep-sea records the LDE is usually characterized by two distinctive XRF Fe peaks, paralleled by a ~0.7 ‰ negative δ13C excursion (prev. publ.). Here we present new stable isotope and faunal datasets from planktic foraminifera representing three ocean basins: The Pacific is covered by ODP Site 1210, the South Atlantic by ODP Site 1262 and the North Atlantic by IODP Site U1407. We compare the generated datasets in aspects of biotic response (planktic foraminifera), carbonate preservation as well as δ18O and δ13C signals of surface, subsurface and benthic taxa covering a time span of 900 kyr around the event to figure out to what extent the LDE influenced oceans and biota. At Site 1210 a drop in planktic and benthic δ18O record suggest a temperature rise of ~2.5°C within 100 ky which is on the same scale as the benthic δ18O shift at 1209 (prev. publ.) suggesting the LDE to be a further potential Paleocene hyperthermal. Multivariate statistics imply distinct faunal changes starting below the LDE. A different assemblage after the event was observed specifically in photosymbiont-bearing taxa including the disappearance of Praemurica spp. and the strong increase of Igorina albeari . Minor dissolution is considered to be present during the LDE according to enhanced test fragmentation and decreased CaCO3 and planktic foraminifera test abundance. A rising δ13C gradient between surface and subsurface dwelling foraminifera suggests sudden increased stratification of the upper water column ~100 ky below the LDE, strongly enhanced during it and less but still high above it. This might include a shallower thermocline and be linked to the development of a deep-chlorophyll maximum. Faunal assemblages of 1262 show a similar development with an overall higher abundance of subsurface dwellers. Multivariate statistisc

  19. Hydro-acoustic remote sensing of benthic biological communities on the shallow South East Australian continental shelf

    Science.gov (United States)

    Rattray, Alex; Ierodiaconou, Daniel; Laurenson, Laurie; Burq, Shoaib; Reston, Marcus

    2009-09-01

    Information regarding the composition and extent of benthic habitats on the South East Australian continental shelf is limited. In this habitat mapping study, multibeam echosounder (MBES) data are integrated with precisely geo-referenced video ground-truth data to quantify benthic biotic communities at Cape Nelson, Victoria, Australia. Using an automated decision tree classification approach, 5 representative biotic groups defined from video analysis were related to hydro-acoustically derived variables in the Cape Nelson survey area. Using a combination of multibeam bathymetry, backscatter and derivative products produced highest overall accuracy (87%) and kappa statistic (0.83). This study demonstrates that decision tree classifiers are capable of integrating variable data types for mapping distributions of benthic biological assemblages, which are important in maintaining biodiversity and other system services in the marine environment.

  20. The O2, pH and Ca2+ microenvironment of benthic foraminifera in a high CO2 world.

    Directory of Open Access Journals (Sweden)

    Martin S Glas

    Full Text Available Ocean acidification (OA can have adverse effects on marine calcifiers. Yet, phototrophic marine calcifiers elevate their external oxygen and pH microenvironment in daylight, through the uptake of dissolved inorganic carbon (DIC by photosynthesis. We studied to which extent pH elevation within their microenvironments in daylight can counteract ambient seawater pH reductions, i.e. OA conditions. We measured the O(2 and pH microenvironment of four photosymbiotic and two symbiont-free benthic tropical foraminiferal species at three different OA treatments (~432, 1141 and 2151 µatm pCO(2. The O(2 concentration difference between the seawater and the test surface (ΔO(2 was taken as a measure for the photosynthetic rate. Our results showed that O(2 and pH levels were significantly higher on photosymbiotic foraminiferal surfaces in light than in dark conditions, and than on surfaces of symbiont-free foraminifera. Rates of photosynthesis at saturated light conditions did not change significantly between OA treatments (except in individuals that exhibited symbiont loss, i.e. bleaching, at elevated pCO(2. The pH at the cell surface decreased during incubations at elevated pCO(2, also during light incubations. Photosynthesis increased the surface pH but this increase was insufficient to compensate for ambient seawater pH decreases. We thus conclude that photosynthesis does only partly protect symbiont bearing foraminifera against OA.

  1. Impacts of discarded plastic bags on marine assemblages and ecosystem functioning.

    Science.gov (United States)

    Green, Dannielle Senga; Boots, Bas; Blockley, David James; Rocha, Carlos; Thompson, Richard

    2015-05-01

    The accumulation of plastic debris is a global environmental problem due to its durability, persistence, and abundance. Although effects of plastic debris on individual marine organisms, particularly mammals and birds, have been extensively documented (e.g., entanglement and choking), very little is known about effects on assemblages and consequences for ecosystem functioning. In Europe, around 40% of the plastic items produced are utilized as single-use packaging, which rapidly accumulate in waste management facilities and as litter in the environment. A range of biodegradable plastics have been developed with the aspiration of reducing the persistence of litter; however, their impacts on marine assemblages or ecosystem functioning have never been evaluated. A field experiment was conducted to assess the impact of conventional and biodegradable plastic carrier bags as litter on benthic macro- and meio-faunal assemblages and biogeochemical processes (primary productivity, redox condition, organic matter content, and pore-water nutrients) on an intertidal shore near Dublin, Ireland. After 9 weeks, the presence of either type of bag created anoxic conditions within the sediment along with reduced primary productivity and organic matter and significantly lower abundances of infaunal invertebrates. This indicates that both conventional and biodegradable bags can rapidly alter marine assemblages and the ecosystem services they provide. PMID:25822754

  2. Macroalgal extracts induce bacterial assemblage shifts and sublethal tissue stress in Caribbean corals.

    Directory of Open Access Journals (Sweden)

    Kathleen M Morrow

    Full Text Available Benthic macroalgae can be abundant on present-day coral reefs, especially where rates of herbivory are low and/or dissolved nutrients are high. This study investigated the impact of macroalgal extracts on both coral-associated bacterial assemblages and sublethal stress response of corals. Crude extracts and live algal thalli from common Caribbean macroalgae were applied onto the surface of Montastraea faveolata and Porites astreoides corals on reefs in both Florida and Belize. Denaturing gradient gel electrophoresis (DGGE of 16S rRNA gene amplicons was used to examine changes in the surface mucus layer (SML bacteria in both coral species. Some of the extracts and live algae induced detectable shifts in coral-associated bacterial assemblages. However, one aqueous extract caused the bacterial assemblages to shift to an entirely new state (Lobophora variegata, whereas other organic extracts had little to no impact (e.g. Dictyota sp.. Macroalgal extracts more frequently induced sublethal stress responses in M. faveolata than in P. astreoides corals, suggesting that cellular integrity can be negatively impacted in selected corals when comparing co-occurring species. As modern reefs experience phase-shifts to a higher abundance of macroalgae with potent chemical defenses, these macroalgae are likely impacting the composition of microbial assemblages associated with corals and affecting overall reef health in unpredicted and unprecedented ways.

  3. Macroalgal extracts induce bacterial assemblage shifts and sublethal tissue stress in Caribbean corals.

    Science.gov (United States)

    Morrow, Kathleen M; Ritson-Williams, Raphael; Ross, Cliff; Liles, Mark R; Paul, Valerie J

    2012-01-01

    Benthic macroalgae can be abundant on present-day coral reefs, especially where rates of herbivory are low and/or dissolved nutrients are high. This study investigated the impact of macroalgal extracts on both coral-associated bacterial assemblages and sublethal stress response of corals. Crude extracts and live algal thalli from common Caribbean macroalgae were applied onto the surface of Montastraea faveolata and Porites astreoides corals on reefs in both Florida and Belize. Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene amplicons was used to examine changes in the surface mucus layer (SML) bacteria in both coral species. Some of the extracts and live algae induced detectable shifts in coral-associated bacterial assemblages. However, one aqueous extract caused the bacterial assemblages to shift to an entirely new state (Lobophora variegata), whereas other organic extracts had little to no impact (e.g. Dictyota sp.). Macroalgal extracts more frequently induced sublethal stress responses in M. faveolata than in P. astreoides corals, suggesting that cellular integrity can be negatively impacted in selected corals when comparing co-occurring species. As modern reefs experience phase-shifts to a higher abundance of macroalgae with potent chemical defenses, these macroalgae are likely impacting the composition of microbial assemblages associated with corals and affecting overall reef health in unpredicted and unprecedented ways. PMID:23028648

  4. 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.

  5. Benthic community of the Savannah River below a peaking hydropower station

    Science.gov (United States)

    Hudson, Patrick L.; Nichols, S. Jerrine

    1986-01-01

    The Savannah River below Hartwell Dam, on the South Carolina-Georgia border, contains at least 206 benthic invertebrate taxa, even though this tailwater undergoes substantial daily fluctuations in water flow, temperature, and dissolved oxygen. Oligochaetes, chironomids, and amphipods dominate the community immediately below the dam. Farther downstream, larger organisms (i.e., Ephemeroptera, Trichoptera, etc.) dominate the benthic community. The high diversity of this system is primarily attributed to the intensive effort we expended to identify invertebrates to species level. We conclude that tailwaters associated with peaking hydropower stations may in fact have the diverse community assemblages found in natural streams and that this has not been recognized by other investigators because the bulk of the fauna is made up of small forms that are easily overlooked. Comparisons of tailwater fauna communities with those in control areas should be limited to rivers of similar size.

  6. Benthic Trophic Interactions in an Antarctic Shallow Water Ecosystem Affected by Recent Glacier Retreat.

    Directory of Open Access Journals (Sweden)

    Francesca Pasotti

    Full Text Available The western Antarctic Peninsula is experiencing strong environmental changes as a consequence of ongoing regional warming. Glaciers in the area are retreating rapidly and increased sediment-laden meltwater runoff threatens the benthic biodiversity at shallow depths. We identified three sites with a distinct glacier-retreat related history and different levels of glacial influence in the inner part of Potter Cove (King George Island, South Shetland Islands, a fjord-like embayment impacted since the 1950s by a tidewater glacier retreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (δ13C and δ15N stable isotope analysis at the three sites to investigate possible glacier retreat-related influences on benthic trophic interactions. The isotopic niches were locally shaped by the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopic niche widths were found at the site that has become ice-free most recently, and narrower niches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance (e.g. via ice-growler scouring species with different strategies could settle. The site at the earliest stage of post-retreat development was characterized by an assemblage with lower trophic redundancy. Generally, the isotopic niche widths increased with increasing size spectra of organisms within the community, excepting the youngest assemblage, where the pioneer colonizer meiofauna size class displayed the highest isotopic niche width. Meiofauna at all sites generally occupied positions in the isotopic space that suggested a detrital-pool food source and/or the presence of predatory taxa. In general ice scour and glacial impact appeared to play a two-fold role within the Cove: i either stimulating trophic diversity by allowing continuous re-colonization of meiofaunal species or, ii over time driving the benthic assemblages into a more compact trophic structure with

  7. Deep-sea foraminifera from the Cassidaigne Canyon (NW Mediterranean): assessing the environmental impact of bauxite red mud disposal.

    Science.gov (United States)

    Fontanier, C; Fabri, M-C; Buscail, R; Biscara, L; Koho, K; Reichart, G J; Cossa, D; Galaup, S; Chabaud, G; Pigot, L

    2012-09-01

    Benthic foraminiferal assemblages were investigated from two sites along the axis of the Cassidaigne Canyon (NW Mediterranean Sea). Both areas are contaminated by bauxite red mud enriched in iron, titanium, vanadium and chromium. These elemental enrichments are related to bauxite-derived minerals and various amorphous phases. At the shallowest station located very close to the pipe outlet, the benthic living foraminiferal community is characterised by a very low diversity and by an unusual dominance of Gyroidina umbonata and Bulimina marginata. The mechanical stress related to downslope transport of red mud is a likely source of hydro-sedimentary pollution precluding the settlement of diverse fauna. The living and dead foraminiferal faunas from the deepest site are typical of oligo-mesotrophic conditions prevailing in natural environments. There, bauxite residues have obviously no environmental impact on foraminiferal faunas. The bioavailability of trace metals is likely low as elemental enrichments were not observed in foraminiferal test chemistry. PMID:22795490

  8. Deep-sea foraminifera from the Cassidaigne Canyon (NW Mediterranean): Assessing the environmental impact of bauxite red mud disposal

    International Nuclear Information System (INIS)

    Benthic foraminiferal assemblages were investigated from two sites along the axis of the Cassidaigne Canyon (NW Mediterranean Sea). Both areas are contaminated by bauxite red mud enriched in iron, titanium, vanadium and chromium. These elemental enrichments are related to bauxite-derived minerals and various amorphous phases. At the shallowest station located very close to the pipe outlet, the benthic living foraminiferal community is characterised by a very low diversity and by an unusual dominance of Gyroidina umbonata and Bulimina marginata. The mechanical stress related to downslope transport of red mud is a likely source of hydro-sedimentary pollution precluding the settlement of diverse fauna. The living and dead foraminiferal faunas from the deepest site are typical of oligo-mesotrophic conditions prevailing in natural environments. There, bauxite residues have obviously no environmental impact on foraminiferal faunas. The bioavailability of trace metals is likely low as elemental enrichments were not observed in foraminiferal test chemistry.

  9. Benthic biodiversity patterns in Ria de Aveiro, Western Portugal: Environmental-biological relationships

    Science.gov (United States)

    Rodrigues, Ana Maria; Quintino, Victor; Sampaio, Leandro; Freitas, Rosa; Neves, Ramiro

    2011-12-01

    This study characterizes the macrobenthic gradients in Ria de Aveiro, Western Portugal. Ria de Aveiro is the meeting place of a number of river basins, resulting in a transition system of complex geometry, with channels running parallel to the coast line, north and south of the entrance, but also inland, creating an intricate system of navigation channels, islands and intertidal sand and mudflats. This renders unique characteristics to this system within the framework of transitional waters. The study was based on the analysis of samples from 248 sites, covering the full salinity gradient and the entire channel system. A total of 120 taxa in more than 76,350 specimens were identified. The most abundant and frequent taxa were all annelids, namely Alkmaria romijni, Streblospio shrubsolii, Tharyx sp., Tubificoides benedii, Nereis diversicolor, Capitella sp., Pygospio elegans, Polydora ligni and an unidentified oligochaete. The spatial distribution of the fauna was found to be mainly related to hydrodynamics and the salinity gradient, whereas sediment grain-size characteristics were much less important. Shear stress, flux, current velocity, salinity and sediment redox potential were the environmental variables which best related to the biological data. Benthic assemblages succeed from the euhaline pole, at the entrance, to the limnetic poles, located in the inner parts of the channels. In this succession, mean abundance increased from the outward to the inward assemblages but species richness and diversity were higher in intermediate assemblages. These descriptors decrease abruptly in the limnetic areas. Using the M-AMBI index, the ecological quality of Ria de Aveiro revealed moderate, poor and bad status. However, the ecological status spatial trend closely followed the benthic assemblages succession, their species richness and diversity, indicating the need for proper reference conditions and inter-calibration exercises in the transition waters before final

  10. 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

  11. 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.

  12. An unusually large phytoplankton spring bloom drives rapid changes in benthic diversity and ecosystem function

    Science.gov (United States)

    Zhang, Qingtian; Warwick, Richard M.; McNeill, Caroline L.; Widdicombe, Claire E.; Sheehan, Aaron; Widdicombe, Stephen

    2015-09-01

    In 2012, the Western English Channel experienced an unusually large and long-lived phytoplankton spring bloom. When compared with data from the past 20 years, average phytoplankton biomass at Station L4 (part of the Western Channel Observatory) was approximately 3× greater and lasted 50% longer than any previous year. Regular (mostly weekly) box core samples were collected from this site before, during and after the bloom to determine its impact on macrofaunal abundance, diversity, biomass, community structure and function. The spring bloom of 2012 was shown to support a large and rapid response in the majority of benthic taxa and functional groups. However, key differences in the precise nature of this response, as well as in its timing, was observed between different macrofauna feeding groups. Deposit feeders responded almost instantly at the start of the bloom, primarily thorough an increase in abundance. Suspension feeders and opportunistic/predatory/carnivorous taxa responded slightly more slowly and primarily with an increase in biomass. At the end of the bloom a rapid decline in macrobenthic abundance, diversity and biomass closely followed the decline in phytoplankton biomass. With suspension feeders showing evidence of this decline a few weeks before deposit feeders, it was concluded that this collapse in benthic communities was driven primarily by food availability and competition. However, it is possible that environmental hypoxia and the presence of toxic benthic cyanobacteria could also have contributed to this decline. This study shows evidence for strong benthic-pelagic coupling at L4; a shallow (50 m), coastal, fine-sand habitat. It also demonstrates that in such habitats, it is not just planktonic organisms that demonstrate clear community phenology. Different functional groups within the benthic assemblage will respond to the spring bloom in specific manner, with implications for key ecosystem functions and processes, such as secondary production

  13. Interlaboratory comparison study of calibration standards for foraminiferal Mg/Ca thermometry

    Science.gov (United States)

    Greaves, M.; Caillon, N.; Rebaubier, H.; Bartoli, G.; Bohaty, S.; Cacho, I.; Clarke, L.; Cooper, M.; Daunt, C.; Delaney, M.; Demenocal, P.; Dutton, A.; Eggins, S.; Elderfield, H.; Garbe-Schoenberg, D.; Goddard, E.; Green, D.; Groeneveld, J.; Hastings, D.; Hathorne, E.; Kimoto, K.; Klinkhammer, G.; Labeyrie, L.; Lea, D. W.; Marchitto, T.; MartíNez-Botí, M. A.; Mortyn, P. G.; Ni, Y.; Nuernberg, D.; Paradis, G.; Pena, L.; Quinn, T.; Rosenthal, Y.; Russell, A.; Sagawa, T.; Sosdian, S.; Stott, L.; Tachikawa, K.; Tappa, E.; Thunell, R.; Wilson, P. A.

    2008-08-01

    An interlaboratory study of Mg/Ca and Sr/Ca ratios in three commercially available carbonate reference materials (BAM RS3, CMSI 1767, and ECRM 752-1) was performed with the participation of 25 laboratories that determine foraminiferal Mg/Ca ratios worldwide. These reference materials containing Mg/Ca in the range of foraminiferal calcite (0.8 mmol/mol to 6 mmol/mol) were circulated with a dissolution protocol for analysis. Participants were asked to make replicate dissolutions of the powdered samples and to analyze them using the instruments and calibration standards routinely used in their laboratories. Statistical analysis was performed in accordance with the International Standardization Organization standard 5725, which is based on the analysis of variance (ANOVA) technique. Repeatability (RSDr%), an indicator of intralaboratory precision, for Mg/Ca determinations in solutions after centrifuging increased with decreasing Mg/Ca, ranging from 0.78% at Mg/Ca = 5.56 mmol/mol to 1.15% at Mg/Ca = 0.79 mmol/mol. Reproducibility (RSDR%), an indicator of the interlaboratory method precision, for Mg/Ca determinations in centrifuged solutions was noticeably worse than repeatability, ranging from 4.5% at Mg/Ca = 5.56 mmol/mol to 8.7% at Mg/Ca = 0.79 mmol/mol. Results of this study show that interlaboratory variability is dominated by inconsistencies among instrument calibrations and highlight the need to improve interlaboratory compatibility. Additionally, the study confirmed the suitability of these solid standards as reference materials for foraminiferal Mg/Ca (and Sr/Ca) determinations, provided that appropriate procedures are adopted to minimize and to monitor possible contamination from silicate mineral phases.

  14. Community structure of foraminiferal communities within temporal biozones from the western Arctic Ocean

    Science.gov (United States)

    Hayek, Lee-Ann C.; Buzas, Martin A.; Osterman, Lisa A.

    2007-01-01

    Community structure is often an overlooked dimension of biodiversity. Knowledge of community structure, the statistical distribution of the relative species abundance vector, makes possible comparisons and contrasts across time, space, and/or environmental conditions. Our results indicate that species of Arctic foraminifera in age-correlated cores from abyssal depths are each best described by log-series distributions. Using this structural information, we were able to determine that structural stability exists for at least 50 ka. The foraminiferal communities in this study show remarkable concordance, distributional similarity and support the neutral theory of biodiversity.

  15. Marine Invertebrate assemblages in southern California

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is a point file of invertebrate site clusters calculated from benthic trawls completed by the Southern California Coastal Water Research Project (SCCWRP). Data...

  16. Nearshore marine fish assemblages in southern California

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fish benthic trawls were completed by the Southern California Coastal Water Research Project (SCCWRP). Data from 425 fisheries independent trawls ranging from 2-215...

  17. Mechanisms of temporary adhesion in benthic animals

    NARCIS (Netherlands)

    Dodou, D.; Breedveld, P.; Winter, J.C.F.; Dankelman, J.; Leeuwen, van J.L.

    2011-01-01

    Adhesive systems are ubiquitous in benthic animals and play a key role in diverse functions such as locomotion, food capture, mating, burrow building, and defence. For benthic animals that release adhesives, surface and material properties and external morphology have received little attention compa

  18. Modern diatom, cladocera, chironomid, and chrysophyte cyst assemblages as quantitative indicators for the reconstruction of past environmental conditions in the Alps. I. Climate

    OpenAIRE

    Lotter, A. F.; H. J. B. Birks; Hofmann, W.; Marchetto, A.

    1997-01-01

    Diatom, chrysophyte cyst, benthic cladocera, planktonic cladocera, and chironomid assemblages were studied in the surface sediments of 68 small lakes along an altitudinal gradient from 300 to 2350 m in Switzerland. In addition, 43 environmental variables relating to the physical limnology, geography, catchment characteristics, climate, and water chemistry were recorded or measured for each lake. The explanatory power of each of these predictor variables for the different biological data-sets ...

  19. Marine Microphytobenthic Assemblage Shift along a Natural Shallow-Water CO2 Gradient Subjected to Multiple Environmental Stressors

    Directory of Open Access Journals (Sweden)

    Vivienne R. Johnson

    2015-12-01

    Full Text Available Predicting the effects of anthropogenic CO2 emissions on coastal ecosystems requires an understanding of the responses of algae, since these are a vital functional component of shallow-water habitats. We investigated microphytobenthic assemblages on rock and sandy habitats along a shallow subtidal pCO2 gradient near volcanic seeps in the Mediterranean Sea. Field studies of natural pCO2 gradients help us understand the likely effects of ocean acidification because entire communities are subjected to a realistic suite of environmental stressors such as over-fishing and coastal pollution. Temperature, total alkalinity, salinity, light levels and sediment properties were similar at our study sites. On sand and on rock, benthic diatom abundance and the photosynthetic standing crop of biofilms increased significantly with increasing pCO2. There were also marked shifts in diatom community composition as pCO2 levels increased. Cyanobacterial abundance was only elevated at extremely high levels of pCO2 (>1400 μatm. This is the first demonstration of the tolerance of natural marine benthic microalgae assemblages to elevated CO2 in an ecosystem subjected to multiple environmental stressors. Our observations indicate that Mediterranean coastal systems will alter as pCO2 levels continue to rise, with increased photosynthetic standing crop and taxonomic shifts in microalgal assemblages.

  20. Accuracy, standardization, and interlaboratory calibration standards for foraminiferal Mg/Ca thermometry

    Science.gov (United States)

    Greaves, Mervyn; Barker, Stephen; Daunt, Caroline; Elderfield, Henry

    2005-02-01

    The use of liquid and solid standards for foraminiferal Mg/Ca and Sr/Ca determinations and interlaboratory calibration has been investigated. Preparation of single element standard solutions from primary solid standard material enables the preparation of mixed standard solutions with Mg/Ca and Sr/Ca ratios of known accuracy to better than 0.1%. We also investigated commercial reference materials to determine whether existing carbonate standards could be used as reference material for Mg/Ca determinations in foraminiferal calcite. We propose that, in the absence of a pure calcium carbonate standard certified for Mg/Ca, ECRM 752-1, a limestone CRM containing Mg/Ca within the range of typical foraminifera, is a suitable solid standard for interlaboratory calibration. Replicate Mg/Ca determinations showed that, provided silicate phases are removed by centrifugation, this material is homogenous within the precision of daily instrumental Mg/Ca determinations over a range of sample weights from 10 to 1000 mg, taken from two separate bottles of ECRM 752-1. Results gave an average value of Mg/Ca = 3.75 mmol/mol (0.015 s.d., 0.41% r.s.d.) on 118 determinations from the two bottles.

  1. A foraminiferal δ(18)O record covering the last 2,200 years.

    Science.gov (United States)

    Taricco, Carla; Alessio, Silvia; Rubinetti, Sara; Vivaldo, Gianna; Mancuso, Salvatore

    2016-01-01

    Thanks to the precise core dating and the high sedimentation rate of the drilling site (Gallipoli Terrace, Ionian Sea) we were able to measure a foraminiferal δ(18)O series covering the last 2,200 years with a time resolution shorter than 4 years. In order to support the quality of this data-set we link the δ(18)O values measured in the foraminifera shells to temperature and salinity measurements available for the last thirty years covered by the core. Moreover, we describe in detail the dating procedures based on the presence of volcanic markers along the core and on the measurement of (210)Pb and (137)Cs activity in the most recent sediment layers. The high time resolution allows for detecting a δ(18)O decennial-scale oscillation, together with centennial and multicentennial components. Due to the dependence of foraminiferal δ(18)O on environmental conditions, these oscillations can provide information about temperature and salinity variations in past millennia. The strategic location of the drilling area makes this record a unique tool for climate and oceanographic studies of the Central Mediterranean. PMID:27328303

  2. Planktic foraminiferal responses to orbital scale oceanographic changes off the western Iberian margin over the last 900 kyr: Results from IODP site U1391

    Science.gov (United States)

    Singh, A. D.; Verma, K.; Jaiswal, S.; Alonso-Garcia, M.; Li, B.; Abrantes, F.

    2015-12-01

    This paper presents planktic foraminiferal assemblage records of the last 900 kyr from the SW Iberian margin (IODP Site U1391). The faunal records show the history of surface oceanographic changes on glacial/interglacial scales before and after the Mid-Brunhes Event (MBE), a period when a major shift in the climate pattern was recorded in other regions. Temporal variations in relative abundances of characteristic species/groups are used to infer changes in the latitudinal position of the polar/Arctic water (% Neogloboquadrina pachyderma sinistral and Turborotalita quinqueloba), influence of the transitional subpolar water mass (% N. pachyderma dextral), and subtropical water (% tropical/subtropical species/group). Past changes in the upwelling intensity and productivity pattern associated with seasonal trade wind strength are inferred from the abundance variations of Globigerina bulloides and G. bulloides + Globigerinita glutinata, respectively. Faunal data reveal the influence of cold water masses (polar/subpolar) at the examined site was more pronounced during glacial stages except for marine isotope stage (MIS) 14 and 16. The magnitude of the polar/subpolar water mass invading the study area was at maximum before the MBE during MIS 18, 20 and 22, resulting in a situation like the present day Arctic Front. Interglacial periods prior to the MBE were also relatively colder than those of the post-MBE. Our faunal based inferences are in agreement with the ice-rafted debris (IRD) concentration and N. pachyderma sinistral records of the subpolar North Atlantic sites. Based on faunal proxies, we recorded major and rapid changes in upwelling intensity and related productivity during glacial Terminations. Both the upwelling intensity and productivity significantly increased after the MBE, particularly during the interglacials MIS 7, 9 and 11. Our productivity record parallels the EPICA CH4 record suggesting teleconnections between trade winds induced productivity and the

  3. Foraminiferal study from Kharo Creek, Kachchh (Gujarat), north west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Chaturvedi, S.K.

    and Ammonia. These reworked foraminifera were earthey coloured, highly polished and severely abraded and typical of high energy environment. These re- worked specimens similar to modern assemblages were indicative of transport from nearshore shallow depths and...

  4. Benthic macrofaunal dynamics and environmental stress across a salt wedge Mediterranean estuary.

    Science.gov (United States)

    Nebra, Alfonso; Alcaraz, Carles; Caiola, Nuno; Muñoz-Camarillo, Gloria; Ibáñez, Carles

    2016-06-01

    The spatial distribution of benthic macroinvertebrate community in relation to environmental factors was studied along the Ebro Estuary (NE Iberian Peninsula), a salt wedge Mediterranean estuary. Both ordination methods and generalized additive models were performed to identify the different benthic assemblages and their relationship to abiotic factors. Our results showed a strong relationship between macrofaunal assemblages and the predominant environmental gradients (e.g. salinity); thus revealing spatial differences in their structure and composition. Two different stretches were identified, namely the upper (UE) and the lower Ebro Estuary (LE). UE showed riverine characteristics and hence was colonized by a freshwater community; whereas LE was influenced by marine intrusion and sustained a complex marine-origin community. However, within each stretch, water and sediment characteristics played an important role in explaining species composition differences among sampling stations. Moreover, outcomes suggested a total species replacement pattern, instead of the nestedness pattern usually associated with well-mixed temperate estuaries. The sharp species turnover together with the estuarine stratification point out that the Ebro Estuary is working, in terms of ecological boundaries, under an ecotone model. Finally, despite obvious differences with well mixed estuaries (i.e. lack of tidal influence, stratification and species turnover), the Ebro Estuary shares important ecological attributes with well-mixed temperate estuaries. PMID:27062106

  5. Climate change and glacier retreat drive shifts in an Antarctic benthic ecosystem.

    Science.gov (United States)

    Sahade, Ricardo; Lagger, Cristian; Torre, Luciana; Momo, Fernando; Monien, Patrick; Schloss, Irene; Barnes, David K A; Servetto, Natalia; Tarantelli, Soledad; Tatián, Marcos; Zamboni, Nadia; Abele, Doris

    2015-11-01

    The Antarctic Peninsula (AP) is one of the three places on Earth that registered the most intense warming in the last 50 years, almost five times the global mean. This warming has strongly affected the cryosphere, causing the largest ice-shelf collapses ever observed and the retreat of 87% of glaciers. Ecosystem responses, although increasingly predicted, have been mainly reported for pelagic systems. However, and despite most Antarctic species being benthic, responses in the Antarctic benthos have been detected in only a few species, and major effects at assemblage level are unknown. This is probably due to the scarcity of baselines against which to assess change. We performed repeat surveys of coastal benthos in 1994, 1998, and 2010, analyzing community structure and environmental variables at King George Island, Antarctica. We report a marked shift in an Antarctic benthic community that can be linked to ongoing climate change. However, rather than temperature as the primary factor, we highlight the resulting increased sediment runoff, triggered by glacier retreat, as the potential causal factor. The sudden shift from a "filter feeders-ascidian domination" to a "mixed assemblage" suggests that thresholds (for example, of tolerable sedimentation) and alternative equilibrium states, depending on the reversibility of the changes, could be possible traits of this ecosystem. Sedimentation processes will be increasing under the current scenario of glacier retreat, and attention needs to be paid to its effects along the AP. PMID:26702429

  6. Foram Farming in the Mid-Continent: Culturing Low-Mg Benthic Foraminifera to Calibrate the Mg/Ca Paleothermometer

    Science.gov (United States)

    Jennings, D.; Hasiuk, F.; Thomas, E.; Varekamp, J. C.

    2014-12-01

    The initiation of Cenozoic continental ice sheets and the history of their growth/decay is difficult to reconstruct because of the mixed effects of polar ice volume and temperature on benthic foraminiferal oxygen isotope values. Coupled measurements of foraminiferal δ18O and Mg/Ca are a promising tool to unlock the history of past continental glaciation by calculating the oxygen isotopic composition of paleo-seawater. This method has been applied on Quaternary timescales with success, but uncertainty about secular changes in seawater Mg/Ca and potential changes in carbonate saturation have produced varying results with deeper time data. Currently, no experimentally-calibrated model explains how the Mg/Ca of low-Mg calcite, such as secreted by benthic foraminifera, responds to variations in seawater temperature and Mg/Ca. Our "Foram Farm" is a culture system for low-Mg calcite benthic foraminifera, composed of a colony and an experimental line. Currently, the colony hosts several species of rotaliids, miliolids, and buliminids obtained from Qatar, the Dominican Republic, Scotland, and Long Island Sound, USA. In addition, two tanks contain "live sand," a mixture of sandy material and seawater obtained from tropical reefs, and commonly used to condition hobbyist saltwater aquaria. This sand contains foraminifera and numerous other microorganisms. "Live sand" could be a source for cheap and easy to obtain test subjects. The foram farm gives access to a constant supply and variety of test subjects for the experimental line, which consists of several analytical refrigerators with varying temperatures. Each refrigerator houses petri dishes where forams are grown in water with varying Mg/Ca compositions. Elphidium excavatum, a well-researched, eurytopic taxon, will be the first to be cultured in the experimental line. After growing under experimental conditions, specimens will be analyzed using LA-ICP-MS, in order to model effects of seawater T and Mg/Ca on foram Mg

  7. Exploring the links between natural products and bacterial assemblages in the sponge Aplysina aerophoba.

    Science.gov (United States)

    Sacristán-Soriano, Oriol; Banaigs, Bernard; Casamayor, Emilio O; Becerro, Mikel A

    2011-02-01

    The sponge Aplysina aerophoba produces a large diversity of brominated alkaloids (BAs) and hosts a complex microbial assemblage. Although BAs are located within sponge cells, the enzymes that bind halogen elements to organic compounds have been exclusively described in algae, fungi, and bacteria. Bacterial communities within A. aerophoba could therefore be involved in the biosynthesis of these compounds. This study investigates whether changes in both the concentration of BAs and the bacterial assemblages are correlated in A. aerophoba. To do so, we quantified major natural products using high-performance liquid chromatography and analyzed bacterial assemblages using denaturing gradient gel electrophoresis on the 16S rRNA gene. We identified multiple associations between bacteria and natural products, including a strong relationship between a Chloroflexi phylotype and aplysinamisin-1 and between an unidentified bacterium and aerophobin-2 and isofistularin-3. Our results suggest that these bacteria could either be involved in the production of BAs or be directly affected by them. To our knowledge, this is one of the first reports that find a significant correlation between natural products and bacterial populations in any benthic organism. Further investigating these associations will shed light on the organization and functioning of host-endobiont systems such as Aplysina aerophoba. PMID:21115701

  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. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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...

  14. A Benthic Macroinvertebrate Multimetric Index for Assessment of the Ecological Integrity of Northeast Streams, Thailand

    Directory of Open Access Journals (Sweden)

    Nantiya Rattanachan

    2016-07-01

    Full Text Available This study aims to develop a benthic macroinvertebrate multimetric index for assessing the ecological quality of streams in Northeastern Thailand. ANOSIM indicated that the benthic macroinvertebrate assemblage in both of each basin and each season were not significantly different (R = 0.09, p = 0.24 and R = 0.07, p = 0.35, respectively. The efficacy metrics of each basin consisting of the Mekong II, the Chi, and the Mun basins were integrated and calibrated. A total of 255 data sets of water physico-chemical and benthic macroinvertebrates during the dry period (cool and hot seasons were obtained. The stream classification could be divided into three groups: the reference group (48 stations, the stressed group (42 stations, and the intermediate group (165 stations. Twelve out of 56 metrics have been considered as a core metric for the development of a biological index for quality streams in the Northeast, including Total taxa, EPT taxa, Ephemeroptera taxa, Coleoptera taxa, % EPT, % Chironomidae, % Tolerant individuals, % Intolerant individuals, Beck's index, HBI, Predator taxa, and Clinger taxa. Moreover, this metric set covered the structure and function of organisms including the diversity of species, community structure, tolerance/intolerance measures, functional feeding group, and habit. From the efficacy validation of the biological index, the results of stream assessment corresponded to the classification sites with the physico-chemical characteristics.

  15. Benthic habitat mapping in a Portuguese Marine Protected Area using EUNIS: An integrated approach

    Science.gov (United States)

    Henriques, Victor; Guerra, Miriam Tuaty; Mendes, Beatriz; Gaudêncio, Maria José; Fonseca, Paulo

    2015-06-01

    A growing demand for seabed and habitat mapping has taken place over the past years to support the maritime integrated policies at EU and national levels aiming at the sustainable use of sea resources. This study presents the results of applying the hierarchical European Nature Information System (EUNIS) to classify and map the benthic habitats of the Luiz Saldanha Marine Park, a marine protected area (MPA), located in the mainland Portuguese southwest coast, in the Iberian Peninsula. The habitat map was modelled by applying a methodology based on EUNIS to merge biotic and abiotic key habitat drivers. The modelling in this approach focused on predicting the association of different data types: substrate, bathymetry, light intensity, waves and currents energy, sediment grain size and benthic macrofauna into a common framework. The resulting seamless medium scale habitat map discriminates twenty six distinct sublittoral habitats, including eight with no match in the current classification, which may be regarded as new potential habitat classes and therefore will be submitted to EUNIS. A discussion is provided examining the suitability of the current EUNIS scheme as a standardized approach to classify marine benthic habitats and map their spatial distribution at medium scales in the Portuguese coast. In addition the factors that most affected the results available in the predictive habitat map and the role of the environmental factors on macrofaunal assemblage composition and distribution are outlined.

  16. Ammonite habitat revealed via isotopic composition and comparisons with co-occurring benthic and planktonic organisms

    Science.gov (United States)

    Sessa, Jocelyn Anne; Larina, Ekaterina; Knoll, Katja; Garb, Matthew; Cochran, J. Kirk; Huber, Brian T.; MacLeod, Kenneth G.; Landman, Neil H.

    2015-12-01

    Ammonites are among the best-known fossils of the Phanerozoic, yet their habitat is poorly understood. Three common ammonite families (Baculitidae, Scaphitidae, and Sphenodiscidae) co-occur with well-preserved planktonic and benthic organisms at the type locality of the upper Maastrichtian Owl Creek Formation, offering an excellent opportunity to constrain their depth habitats through isotopic comparisons among taxa. Based on sedimentary evidence and the micro- and macrofauna at this site, we infer that the 9-m-thick sequence was deposited at a paleodepth of 70-150 m. Taxa present throughout the sequence include a diverse assemblage of ammonites, bivalves, and gastropods, abundant benthic foraminifera, and rare planktonic foraminifera. No stratigraphic trends are observed in the isotopic data of any taxon, and thus all of the data from each taxon are considered as replicates. Oxygen isotope-based temperature estimates from the baculites and scaphites overlap with those of the benthos and are distinct from those of the plankton. In contrast, sphenodiscid temperature estimates span a range that includes estimates of the planktonic foraminifera and of the warmer half of the benthic values. These results suggest baculites and scaphites lived close to the seafloor, whereas sphenodiscids sometimes inhabited the upper water column and/or lived closer to shore. In fact, the rarity and poorer preservation of the sphenodiscids relative to the baculites and scaphites suggests that the sphenodiscid shells may have only reached the Owl Creek locality by drifting seaward after death.

  17. 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...

  18. 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.

  19. Variability of South Atlantic Central Water in the last century based on stable isotopes and benthic foraminifera of southeast Brazilian continental shelf.

    Science.gov (United States)

    Barbosa, C. F.; De Faria, G. R.; Albuquerque, A. L.

    2014-12-01

    In order to better understand the changes in productivity and water masses that permeate the bottom of the continental shelf of southeast Brazilian margin influenced by upwelling, three box-cores were collected in a bathymetric transect. Cores were analyzed for assemblage composition of benthic foraminifera and isotopes. 55 samples were analyzed and 227 benthic foraminifera were identified, but only 18 of them showed relative frequencies that contributed to the understanding of both oceanographic dynamics and productivity conditions of the area. There was dominance of Globocassidulina subglobosa, which is considered an indicator of areas with pulses of phytodetritus. Statistical analysis separated samples into different groups according to their location, indicating environmental factors on the continental shelf. Innershore core showed the highest flux of benthic foraminifera and the offshore one showed the major diversity and variation of foraminifera assemblages over time. Mid shelf cores showed little variation of the assemblages and indicate a stable environment. The δ13C values of Uvigerina peregrina indicated more degraded organic matter in the center of the shelf. The mean composition of Cibicides spp. δ13C is, on average, 0.25 ‰ depleted related to the values of δ13CDIC. Such values associated with high frequency of phytodetritus species indicated the formation of a phytodetritus layer at the bottom of the continental shelf of Cabo Frio. The paleotemperature calculated from oxygen isotopes pointed the permanence of SACW at the shelf bottom over the last few centuries.

  20. Ecological and evolutionary consequences of benthic community stasis in the very deep sea (>1500 m)

    Science.gov (United States)

    Buzas, Martin A.; Hayek, Lee-Ann C.; Culver, Stephen J.; Hayward, Bruce W.; Osterman, Lisa E.

    2014-01-01

    An enigma of deep-sea biodiversity research is that the abyss with its low productivity and densities appears to have a biodiversity similar to that of shallower depths. This conceptualization of similarity is based mainly on per-sample estimates (point diversity, within-habitat, or α-diversity). Here, we use a measure of between-sample within-community diversity (β1H) to examine benthic foraminiferal diversity between 333 stations within 49 communties from New Zealand, the South Atlantic, the Gulf of Mexico, the Norwegian Sea, and the Arctic. The communities are grouped into two depth categories: 200–1500 m and >1500 m. β1H diversity exhibits no evidence of regional differences. Instead, higher values at shallower depths are observed worldwide. At depths of >1500 m the average β1H is zero, indicating stasis or no biodiversity gradient. The difference in β1H-diversity explains why, despite species richness often being greater per sample at deeper depths, the total number of species is greater at shallower depths. The greater number of communities and higher rate of evolution resulting in shorter species durations at shallower depths is also consistent with higher β1H values.

  1. Physiological controls on seawater uptake and calcification in the benthic foraminifer Ammonia tepida

    Directory of Open Access Journals (Sweden)

    J. Bijma

    2009-07-01

    Full Text Available During the last decades conceptual models describing the calcification pathway of foraminifera and its physiological controls have been developed. These models are derived by combining data of tracer experiments and microscopic observations obtained from different species. Although vital for understanding their calcitic isotopic and trace elemental composition, direct observational evidence on e.g. seawater vacuolization and intracellular Ca-cycling is lacking for most species. To analyse the relation between seawater uptake and calcification, we incubated juveniles of the cosmopolitan benthic, intertidal foraminifer Ammonia tepida with various fluorescent probes. Visualizing the membranes of endocytosed vesicles was achieved by incubating specimens with the dye FM1-43, while Ca ions in the calcification vesicles were detected by the Ca2+-indicator Fluo3-AM. Uptake of fluorescent latex-beads (0.5 μm diameter and subsequent transport to the site of chamber formation provided additional evidence that endocytosis is related to the calcification pathway and not merely involved in membrane cycling. Our results show for the first time that endocytosis of seawater is part of the calcification process in Ammonia tepida. Data on the intracellular calcium ion-cycling allowed for calculating a preliminary cellular Ca-budget during foraminiferal calcification.

  2. Planktonic Foraminiferal Assemblage Variations of Ontong-Java Plateau during Late Quaternary and Their Implications for Paleotemperature in the Western Pacific Warm Pool

    Institute of Scientific and Technical Information of China (English)

    Jin Haiyan; Jian Zhimin; Tian Jun

    2004-01-01

    Ocean Drilling Program (ODP) Site 807A was recovered from the Ontong-Java plateau, western equatorial Pacific. Quantitative analysis of planktonic foraminifera, combined with oxygen and carbon isotope data, reveals the glacial-interglacial variations of sea-surface temperature and the upper water vertical structure in this region during the late Quaternary. Our results indicate that since 530 ka sea-surface temperature (SST) and the depth of thermocline (DOT) have changed significantly in the western Pacific warm pool (WPWP). The average glacial-interglacial annual SST difference was up to 4.2 ℃, and the DOT fluctuations could exceed more than 100 m, further suggesting the instability of the WPWP. The spectral analyses of SST and DOT reveal two dominating cyclicities-the typical 100 ka cycle and the semi-precessional cycle, which is significant in the tropical spectrum, indicating that late Quaternary paleoceanographic changes in the study area were influenced not only by a high latitude forcing but also by tropic-driving factors.

  3. A hierarchical classification of benthic biodiversity and assessment of protected areas in the Southern Ocean.

    Directory of Open Access Journals (Sweden)

    Lucinda L Douglass

    Full Text Available An international effort is underway to establish a representative system of marine protected areas (MPAs in the Southern Ocean to help provide for the long-term conservation of marine biodiversity in the region. Important to this undertaking is knowledge of the distribution of benthic assemblages. Here, our aim is to identify the areas where benthic marine assemblages are likely to differ from each other in the Southern Ocean including near-shore Antarctica. We achieve this by using a hierarchical spatial classification of ecoregions, bathomes and environmental types. Ecoregions are defined according to available data on biogeographic patterns and environmental drivers on dispersal. Bathomes are identified according to depth strata defined by species distributions. Environmental types are uniquely classified according to the geomorphic features found within the bathomes in each ecoregion. We identified 23 ecoregions and nine bathomes. From a set of 28 types of geomorphic features of the seabed, 562 unique environmental types were classified for the Southern Ocean. We applied the environmental types as surrogates of different assemblages of biodiversity to assess the representativeness of existing MPAs. We found that 12 ecoregions are not represented in MPAs and that no ecoregion has their full range of environmental types represented in MPAs. Current MPA planning processes, if implemented, will substantially increase the representation of environmental types particularly within 8 ecoregions. To meet internationally agreed conservation goals, additional MPAs will be needed. To assist with this process, we identified 107 spatially restricted environmental types, which should be considered for inclusion in future MPAs. Detailed supplementary data including a spatial dataset are provided.

  4. Bioerosion by microbial euendoliths in benthic foraminifera from heavy metal-polluted coastal environments of Portovesme (South-Western Sardinia, Italy

    Directory of Open Access Journals (Sweden)

    A. Cherchi

    2012-08-01

    Full Text Available A monitoring survey of the coastal area facing the industrial area of Portoscuso-Portovesme (South-Western Sardinia, Italy revealed intense bioerosional processes. Benthic foraminifera collected at the same depth (about 2 m but at different distances from the pollution source show extensive microbial infestation, anomalous Mg/Ca molar ratios and high levels of heavy metals in the shell associated with a decrease in foraminifera richness, population density and biodiversity with the presence of morphologically abnormal specimens. We found that carbonate dissolution induced by euendoliths is selective, depending on the Mg content and morpho-structural types of foraminiferal taxa. This study provides evidences for a connection between heavy metal dispersion, decrease in pH of the sea-water and bioerosional processes on foraminifera.

  5. Benthic Habitats of the Florida Keys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The benthic habitats of the Florida Keys were mapped from a series of 450 aerial photographs. Ecologists outlined the boundaries of specific habitat types by...

  6. BENTHIC MACROFAUNAL ALIENS IN WILLAPA BAY

    Science.gov (United States)

    Benthic macrofaunal samples were collected at random stations in Willapa Bay, WA, in four habitats [eelgrass (Zostera marina), Atlantic cordgrass (Spartina alterniflora), mud shrimp (Upogebia pugettensis), ghost shrimp (Neotrypaea californiensis)] in 1996 and in seven habitats (Z...

  7. Feasibility of remote sensing benthic microalgae

    Science.gov (United States)

    Zingmark, R. G.

    1979-01-01

    Results of data analyses from multispectral scanning data are presented. The data was collected in July 1977 for concentration of chlorophyll in benthic microalgae (mainly diatoms) on an estuary mudflat.

  8. Larger Foraminifera from the Spermonde Archipelago (Sulawesi, Indonesia)

    NARCIS (Netherlands)

    Troelstra, S.R.; Jonkers, H.M.; Rijk, de S.

    1996-01-01

    A systematic description of the distributional patterns of larger symbiont-bearing benthic Foraminifera from the Spermonde Archipelago (Sulawesi, Indonesia) and their relation with local coral reef growth is presented. The larger Foraminiferal assemblages and diversity indices correspond with the di

  9. Deep-sea foraminifera from the Cassidaigne Canyon (NW Mediterranean): Assessing the environmental impact of bauxite red mud disposal

    NARCIS (Netherlands)

    Fontanier, C.; Fabri, M.-C.; Buscail, R.; Biscara, L.; Koho, K.A.; Reichart, G.-J.; Cossa, D.; Galaup, S.; Chabaud, G.; Pigot, L.

    2012-01-01

    Benthic foraminiferal assemblages were investigated from two sites along the axis of the Cassidaigne Canyon (NW Mediterranean Sea). Both areas are contaminated by bauxite red mud enriched in iron, titanium, vanadium and chromium. These elemental enrichments are related to bauxite-derived minerals an

  10. Impacts of maintenance channel dredging in a northern Adriatic coastal lagoon. II: Effects on macrobenthic assemblages in channels and ponds

    Science.gov (United States)

    Ponti, Massimo; Pasteris, Andrea; Guerra, Roberta; Abbiati, Marco

    2009-10-01

    Coastal lagoons are ephemeral habitats whose conservation requires human intervention, such as maintenance dredging of inner channels. Dredging can reduce the abundance of benthic species due to the removal of individuals with the sediment, modify sediment properties, and resuspend fine sediment, nutrients and pollutants, which can lead to eutrophication, hypoxic events and increasing toxicity. Both direct effects in the dredged channel and possible indirect effects in surrounding shallow areas could be expected. This study assesses the effects of the channel maintenance dredging, performed between October 2004 and August 2005, on the invertebrate assemblages both in channels and adjacent ponds in the northern Adriatic coastal lagoon of Pialassa Baiona. The lagoon is affected by eutrophication, chemical and thermal pollution from wastewater treatment and power plants. Three impacted sites were located in the dredged channel and three in the adjacent interconnected shallow water ponds, while three non-impacted sites were located in a channel and in a pond far from the dredged area. Replicate samples were collected from each site one time before and one time after the dredging operations. Despite the extent of the intervention, effects of the dredging on macrobenthic assemblages were detected only within the dredged channel, while in the surrounding ponds no clear and unequivocal effects were found. In particular the dredging could have promoted the increase of the abundance of the polychaete Streblospio shrubsolii in the southern and central parts of the dredged channel and the increase in abundance of the amphipod Corophium insidiosum in the northern side, compared to the controls. Instead, species diversity was reduced in the central and northern parts of the dredged channel. These effects on the macrobenthic invertebrate assemblages could be related to the observed changes of sediment characteristics, contamination and toxicity. Overall, direct effects on benthic

  11. Anchor ice and benthic disturbance in shallow Antarctic waters: interspecific variation in initiation and propagation of ice crystals.

    Science.gov (United States)

    Denny, Mark; Dorgan, Kelly M; Evangelista, Dennis; Hettinger, Annaliese; Leichter, James; Ruder, Warren C; Tuval, Idan

    2011-10-01

    Sea ice typically forms at the ocean's surface, but given a source of supercooled water, an unusual form of ice--anchor ice--can grow on objects in the water column or at the seafloor. For several decades, ecologists have considered anchor ice to be an important agent of disturbance in the shallow-water benthic communities of McMurdo Sound, Antarctica, and potentially elsewhere in polar seas. Divers have documented anchor ice in the McMurdo communities, and its presence coincides with reduced abundance of the sponge Homaxinella balfourensis, which provides habitat for a diverse assemblage of benthic organisms. However, the mechanism of this disturbance has not been explored. Here we show interspecific differences in anchor-ice formation and propagation characteristics for Antarctic benthic organisms. The sponges H. balfourensis and Suberites caminatus show increased incidence of formation and accelerated spread of ice crystals compared to urchins and sea stars. Anchor ice also forms readily on sediments, from which it can grow and adhere to organisms. Our results are consistent with, and provide a potential first step toward, an explanation for disturbance patterns observed in shallow polar benthic communities. Interspecific differences in ice formation raise questions about how surface tissue characteristics such as surface area, rugosity, and mucus coating affect ice formation on invertebrates. PMID:22042434

  12. Diel variability in seawater pH relates to calcification and benthic community structure on coral reefs.

    Directory of Open Access Journals (Sweden)

    Nichole N Price

    Full Text Available Community structure and assembly are determined in part by environmental heterogeneity. While reef-building corals respond negatively to warming (i.e. bleaching events and ocean acidification (OA, the extent of present-day natural variability in pH on shallow reefs and ecological consequences for benthic assemblages is unknown. We documented high resolution temporal patterns in temperature and pH from three reefs in the central Pacific and examined how these data relate to community development and net accretion rates of early successional benthic organisms. These reefs experienced substantial diel fluctuations in temperature (0.78°C and pH (>0.2 similar to the magnitude of 'warming' and 'acidification' expected over the next century. Where daily pH within the benthic boundary layer failed to exceed pelagic climatological seasonal lows, net accretion was slower and fleshy, non-calcifying benthic organisms dominated space. Thus, key aspects of coral reef ecosystem structure and function are presently related to natural diurnal variability in pH.

  13. Using Regional Distribution of Estuarine and Coastal Benthic Invertebrates to Calibrate Benthic Indices of Ecological Condition

    Science.gov (United States)

    The biogeography of marine benthic macroinvertebrates of the U.S. Atlantic coast from Delaware Bay north to Passamaquoddy Bay, Maine, was studied to define physical-chemical factors affecting broad taxa distributions and provide information needed to calibrate benthic indices of ...

  14. 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.

  15. Preliminary report on the study of benthic foraminiferal content in the marine sediment of Queen Maud Land Shelf, Lazarev Sea, Antarctic

    Digital Repository Service at National Institute of Oceanography (India)

    Sinha, R.; Nigam, R.; Khare, N.; Ingole, B.S.; Ghosh, D.N.

    During the 4th and 6th Indian Expedition to Antarctica, surface sediment samples were collected from eight stations in the Queen Maud Land Shelf, Lazarev Sea from the depth ranging from 157 to 785 m. The mean biomass of these samples is 3057...

  16. Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the Southwest Pacific

    Directory of Open Access Journals (Sweden)

    K. M. Pascher

    2015-07-01

    Full Text Available The Eocene was characterised by "greenhouse" climate conditions that were gradually terminated by a long-term cooling trend through the middle and late Eocene. This long-term trend was determined by several large-scale climate perturbations that culminated in a shift to "ice-house" climates at the Eocene–Oligocene Transition. Geochemical and micropaleontological proxies suggest that tropical-to-subtropical sea-surface temperatures persisted into the late Eocene in the high-latitude Southwest Pacific Ocean. Here, we present radiolarian microfossil assemblage and foraminiferal oxygen and carbon stable isotope data from Deep Sea Drilling Project (DSDP Sites 277, 280, 281 and 283 from the middle Eocene to early Oligocene (~ 40–33 Ma to identify oceanographic changes in the Southwest Pacific across this major transition in Earth's climate history. The Middle Eocene Climatic Optimum at ~ 40 Ma is characterised by a negative shift in foraminiferal oxygen isotope values and a radiolarian assemblage consisting of about 5 % of low latitude taxa Amphicraspedum prolixum group and Amphymenium murrayanum. In the early late Eocene at ~ 37 Ma, a positive oxygen isotope shift can be correlated to the Priabonian Oxygen Isotope Maximum (PrOM event – a short-lived cooling event recognized throughout the Southern Ocean. Radiolarian abundance, diversity, and preservation increase during the middle of this event at Site 277 at the same time as diatoms. The PrOM and latest Eocene radiolarian assemblages are characterised by abundant high-latitude taxa. These high-latitude taxa also increase in abundance during the late Eocene and early Oligocene at DSDP Sites 280, 281 and 283 and are associated with very high diatom abundance. We therefore infer a~northward expansion of high-latitude radiolarian taxa onto the Campbell Plateau towards the end of the late Eocene. In the early Oligocene (~ 33 Ma there is an overall decrease in radiolarian abundance and diversity at

  17. Effects of engineered application of Eichhornia crassipes on the benthic macroinvertebrate diversity in Lake Dianchi, an ultra-eutrophic lake in China.

    Science.gov (United States)

    Zhang, Zhiyong; Wang, Zhi; Zhang, Zhenghua; Zhang, Junqian; Guo, Junyao; Li, Enhua; Wang, Xuelei; Liu, Haiqin; Yan, Shaohua

    2016-05-01

    An ecological engineering project with confined growth of 1.5 km(2) of Eichhornia crassipes was implemented to remove pollutants in Lake Dianchi. To assess the ecological effects of this project on benthic macroinvertebrate assemblages, a 1-year investigation at the areas inside and outside E. crassipes mats was conducted from May 2013 to May 2014. All the 10 sampling sites in the areas were grouped into two statistically significant clusters mainly corresponding to inside and outside E. crassipes mat areas (EMAs), by clustering analysis. E. crassipes reduced the densities of pollution indicator taxa (e.g., Oligochaeta and Chironomidae larvae); thus, the total densities of benthic macroinvertebrates at the area inside EMAs (mean 328.2 ind./m(2)) were slightly lower than that at the area outside EMAs (mean 505.6 ind./m(2)). Four functional feeding groups including 38 species of benthic macroinvertebrates were collected at the area inside EMAs, while only three functional feeding groups containing 17 species were collected at the area outside EMAs. The biodiversity indices (Shannon-Weiner, Margalef, Simpson, and Peilou indices) and K-dominance curves also showed higher diversity of benthic macroinvertebrates at the area inside EMAs than at the area outside EMAs. These results suggested that a certain scale of engineering application of E. crassipes was beneficial to benthic macroinvertebrate communities in the ultra-eutrophic Lake Dianchi and it could be used as a pioneer species in ultra-eutrophic lake for pollutant removal. PMID:26780060

  18. Evaluation of foraminiferal trace element cleaning protocols on the Mg/Ca of marine ostracod genus Krithe

    OpenAIRE

    Gray, W.; Holmes, J.; Shevenell, A.

    2014-01-01

    The Mg/Ca of calcite from the marine ostracod genus Krithe may be an important tool for reconstructing past changes in oceanic bottom water temperature (150–4000 m water depth). Rigorous cleaning procedures, routinely used to remove clays, organic matter and Fe–Mn oxyhydroxide coatings in trace element studies of foraminifera, are not regularly applied to marine ostracods despite the potential for Mg contamination. Here we apply standard oxidative and reductive foraminiferal cleaning procedur...

  19. Calibration, validation and application of foraminiferal carbonate based proxies. Reconstructing temperature, salinity and sea water Mg/Ca

    OpenAIRE

    de Wit, J. C.

    2012-01-01

    The chemistry of the calcite test of foraminifera is often relating to the environmental conditions under which they lived. These so-called proxy-relations are regularly used as a tool to reconstruct past climates. Accuracy of these proxies is, however, often limited due to uncertainties or absence of proxy-parameter calibrations. This thesis focuses on the calibration, validation and application of new and existing foraminiferal carbonate based paleo-climate proxies. Several processes, such ...

  20. Spatial variation of hermatypic coral assemblages in Cayos Cochinos Archipelago, Honduras Variación espacial de los ensamblajes de corales hermatípicos en el archipiélago Cayos Cochinos, Honduras

    OpenAIRE

    Rodríguez-Zaragoza, Fabián A.; Carlos V. Pérez-de Silva; Miguel A. Ruiz-Zárate; Amílcar L. Cupul-Magaña; Marco Ortiz; Alicia Medina-Hernández; Pablo Rico; María R. Priego-Arenas; Álvaro Hernández-Flores

    2012-01-01

    Spatial variations of hermatypic coral assemblages were evaluated at five sites in Cayos Cochinos Archipelago, Honduras, in February 2008. Richness and coverage of corals and other benthic morpho-functional groups were estimated using 56 videotransects. Topographic complexity and depth were also measured by transect. Twenty-two coral taxa were recorded for Cayos Cochinos. Total species richness was similar (16 and 17 taxa) at all sites, whereas species richness by transect was different among...

  1. 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

  2. Bacterial Plasmids in Antarctic Natural Microbial Assemblages

    OpenAIRE

    Kobori, Hiromi; Sullivan, Cornelius W.; Shizuya, Hiroaki

    1984-01-01

    Samples of psychrophilic and psychrotrophic bacteria were collected from sea ice, seawater, sediments, and benthic or ice-associated animals in McMurdo Sound, Antarctica. A total of 155 strains were isolated and tested for the presence of plasmids by DNA agarose gel electrophoresis. Thirty-one percent of the isolates carried at least one kind of plasmid. Bacterial isolates taken from sediments showed the highest plasmid incidence (42%), and isolates from seawater showed the lowest plasmid inc...

  3. 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

  4. Disturbance of benthic macrofauna in relation to hypoxia and organic enrichment in a eutrophic coastal bay.

    Science.gov (United States)

    Kodama, Keita; Lee, Jeong-Hoon; Oyama, Masaaki; Shiraishi, Hiroaki; Horiguchi, Toshihiro

    2012-05-01

    This study demonstrated the spatiotemporal patterns of the environmental conditions and benthic macrofauna in Tokyo Bay, Japan, and investigated the factors causing disturbances in the assemblage structure. In the north-central areas, the density and species diversity of the macrobenthos was low. Although hypoxia appeared in July, defaunation occurred in August. The delayed defaunation and recolonization soon after the abatement of hypoxia were attributed to several polychaete and bivalve species that were tolerant to the hypoxic environment. In the southeastern areas, however, the density and species diversity of the macrobenthos was high throughout the year, and no defaunation was recorded. Multivariate analyses showed that the disturbance in the macrofauna correlated with organic enrichment in the sediment and bottom-water hypoxia. There is a concern about further impairment of the macrofauna in the bay due to the expansion of sediment with high levels of organic matter towards the southern regions that could cause hypoxia and subsequent defaunation. PMID:21880357

  5. Sensitivity of Coastal Environments and Wildlife to Spilled Oil: South Florida: BENTHIC (Benthic Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains benthic habitats, including coral reef and hardbottom, seagrass, algae, and others in [for] South Florida. Vector polygons in the data set...

  6. Post-depositional alteration of benthic foraminifera in a methane seep environment

    Science.gov (United States)

    Schneider, Andrea; Cremiere, Antoine; Panieri, Giuliana; Lepland, Aivo; Knies, Jochen

    2016-04-01

    Benthic foraminifera tests from the sediment cores taken from the Vestnesa Ridge, one of the northernmost known marine methane hydrate reservoir, were studied for their visual appearance, mineral and stable carbon isotopic composition in order to explore their indicator potential in a methane seep environment. The Vestnesa Ridge is a sediment drift located in 1200m water depth at 79°N at Svalbar&dacute; s northwestern continental margin. Observations of gas flares originating from pockmarks that are aligned along the crest of the ridge show ongoing methane emission. A distinct sediment layer containing a fossilized assemblage of chemosynthetic bivalves indicates methane seepage activity at least in the late Pleistocene. We have examined the state of preservation and geochemical characteristics of foraminifera tests from this bivalve shell horizon. Tests of the benthic foraminifera species Cassidulina neoteretis display a variable degree of post-depositional alteration and formation of diagenetic carbonate overgrowths on calcitic primary tests. Using binoculars, scanning electron microscope imagery and energy dispersive x-ray spectroscopy, we distinguish visually and mineralogically different diagenetic phases on the external and internal test surfaces. Pristine and smooth test surfaces act as nucleation templates for precipitation of authigenic Mg-calcite crystals causing complete filling of chambers and encrustation of the external test surfaces. The presence of Mg-calcite indicates the overgrowth is precipitating in sulfate-poor sediments. In addition to benthic foraminifera, we have studied the mineralogical and stable carbon and oxygen isotope composition of authigenic carbonate nodules found in the bivalve shell horizon. The mineralogical nature of the carbonates and overgrowths on the foraminifera tests were found to be identical. The δ13C value of the carbonate nodules is as low as -32.3‰ indicating their methane-derived origin. Authigenic carbonate

  7. Effects of acid mine drainage on water, sediment and associated benthic macroinvertebrate communities

    International Nuclear Information System (INIS)

    The toxic constituents of abandoned mined land (AML) discharges (acidic pH, heavy metals, total suspended solids) are extremely toxic to aquatic life . Studies were undertaken to ascertain environmental impacts to the upper Powell River, Lee and Wise Counties, Va. These impacts included disruptions in physical water quality, sediment quality, altered benthic macroinvertebrate assemblages, and toxicity of the water column and sediments from short-term impairment bioassays, and the potential to bioaccumulate selected metals (Al, Fe, Mn, P, Zn, Cu, Mg, S, Ni, Cd) by periphyton and resident bivalves. Water chemistry and macroinvertebrate assemblages were collected at upstream control, just below acid mine drainage and other downstream sites. Selected trace metal concentrations (Al, Fe, Mn, P, Zn, Cu, Mg, S, Ni, Cd) were determined for water, sediment and resident bivalves using ICP-AES. Acidic pH ranged from 2.15--3.3 at three AML-influenced seeps and varied from 6.4--8.0 at reference stations. At one AML-influenced creek, acidic pH conditions worsened from summer to fall and eradicated aquatic life throughout a 1.5 km stretch of that creek as it flowed into another creek. An additional dilution of 3.4 km in the second creek was needed to nearly neutralize the acidic pH problem. Conductivity (umhos/cm) ranged from 32--278 at reference sites and from 245--4,180 at AML-impact sites. Benthic macroinvertebrate abundance and taxon richness were essentially eliminated in the seeps or reached numbers of 1 -3 taxa totaling < 10 organisms relative to reference areas where richness values were 12--17 and comprised 300--977 organisms. Concentrations of Fe, Al, Mg and Cu and Zn were highest in the environmentally stressed stations of low pH and high conductivity relative to the reference stations. Iron was, by far, the element in highest concentration followed by Al and Mg

  8. Extensive metazoan reefs from the Ediacaran Nama Group, Namibia: the rise of benthic suspension feeding.

    Science.gov (United States)

    Wood, R; Curtis, A

    2015-03-01

    We describe new, ecologically complex reef types from the Ediacaran Nama Group, Namibia, dated at ~548 million years ago (Ma), where the earliest known skeletal metazoans, Cloudina riemkeae and Namacalathus, formed extensive reefs up to 20 m in height and width. C. riemkeae formed densely aggregating assemblages associated with microbialite and thrombolite, each from 30 to 100 mm high, which successively colonised former generations to create stacked laminar or columnar reef frameworks. C. riemkeae individuals show budding, multiple, radiating attachment sites and cementation between individuals. Isolated Namacalathus either intergrew with C. riemkeae or formed dense, monospecific aggregations succeeding C. riemkeae frameworks, providing a potential example of environmentally mediated ecological succession. Cloudina and Namacalathus also grow cryptically, either as pendent aggregations from laminar crypt ceilings in microbial framework reefs or as clusters associated with thrombolite attached to neptunian dyke walls. These reefs are notable for their size, exceeding that of the succeeding Lower Cambrian archaeocyath-microbial communities. The repeated colonisation shown by C. riemkeae of former assemblages implies philopatric larval aggregation to colonise limited favourable substrates. As such, not only were skeletal metazoans more important contributors to reef building in the Ediacaran, but there were also more variable reef types with more complex ecologies, than previously thought. Such an abundance of inferred suspension feeders with biomineralised skeletons indicates the efficient exploitation of new resources, more active carbon removal with a strengthened energy flow between planktic and benthic realms, and the rise of biological control over benthic carbonate production. These mark the prelude to the Cambrian Explosion and the modernisation of the global carbon cycle. PMID:25556318

  9. Allelopathy in benthic and littoral areas : case studies on allelochemicals from benthic cyanobacteria and submersed macrophytes

    OpenAIRE

    Gross, Elisabeth

    1999-01-01

    Photosynthetic organisms in littoral and benthic habitats are in general situated in close proximity to their competitors. Benthic algae and cyanobacteria compete for space and grow adjacent to each other. Submersed macrophytes can be overgrown by epiphytic algae and are surrounded by other macrophytes and phytoplankton. The particular spatial setup in these habitats makes allelopathy a powerful strategy. Released compounds can more or less directly reach and act on target organisms. Allelopa...

  10. Assessing the influence of source distance and hydroecoregion on the invertebrate assemblage similarity in central Italy streams

    Directory of Open Access Journals (Sweden)

    Traversetti L.

    2014-04-01

    Full Text Available Increasing the river habitat safeguard level is one of the main actions proposed by the European Water Framework Directive in the field of biomonitoring. To do so, watercourses within the same hydroecoregions (that is, homogeneous areas based on climate, geology and topography ought to be compared. In addition, the source distance was thought to play an important role in comparing rivers and then planning monitoring activities. The purpose of this study was to evaluate if both hydroecoregion and source distance affect the response (in terms of taxa assemblage of one of the most used group in the river monitoring activities: the benthic macroinvertebrate. Here we proposed the comparative influence of hydroecoregion and source distance on the invertebrate assemblage in Mediterranean rivers of central Italy. Our statistical outputs highlighted how macroinvertebrate differed for both hydroecoregions and source distance ranks. In particular, no differences were found among sites of different (1 source distance ranks and (2 hydroecoregion (that is, when this two descriptors were analyzed separately, while the highest difference in the macroinvertebrate assemblage was observed between the same source distance ranks of different hydroecoregions. Our results showed how the use of both hydroecoregion and source distance should be considered for planning monitoring activities to properly manage rivers and water resources.

  11. Cyclicity in the Late Holocene monsoonal changes from the western Bay of Bengal: Foraminiferal approach.

    Digital Repository Service at National Institute of Oceanography (India)

    Rana, S.S.; Nigam, R.

    sediment to 153/g sediment with highest abundance reported at 78 - 80 cm and the lowest at 10 - 12 cm. In the Power spectrum plots, abundance of total benthics (Fig. 4A) is showing periodicity of 250, 175 and 145 yr at 95%- Chi2 while Bulimina marginata... series for humidity or precipitation based on C3 plants which were very similar to the atmospheric ?14 C-derived periodicities of solar variability (Stuiver et al., 1991). Similarly, a series of periodicities in climatic events have been deciphered based...

  12. Predicting estuarine benthic production using functional diversity

    Directory of Open Access Journals (Sweden)

    Marina Dolbeth

    2014-05-01

    Full Text Available We considered an estuarine system having naturally low levels of diversity, but attaining considerable high production levels, and being subjected to different sorts of anthropogenic impacts and climate events to investigate the relationship between diversity and secondary production. Functional diversity measures were used to predict benthic production, which is considered as a proxy of the ecosystem provisioning services. To this end, we used a 14-year dataset on benthic invertebrate community production from a seagrass and a sandflat habitat and we adopted a sequential modeling approach, where abiotic, trait community weighted means (CWM and functional diversity indices were tested by generalized linear models (GLM, and their significant variables were then combined to produce a final model. Almost 90% of variance of the benthic production could be predicted by combining the number of locomotion types, the absolute maximum atmospheric temperature (proxy of the heat waves occurrence, the type of habitat and the mean body mass, by order of importance. This result is in agreement with the mass ratio hypothesis, where ecosystem functions/services can be chiefly predicted by the dominant trait in the community, here measured as CWM. The increase of benthic production with the number of locomotion types may be seen as greater possibility of using the resources available in the system. Such greater efficiency would increase production. The other variables were also discussed in line of the previous hypothesis and taking into account the general positive relationship obtained between production and functional diversity indices. Overall, it was concluded that traits representative of wider possibilities of using available resources and higher functional diversity are related with higher benthic production.

  13. Inter-species and Seasonal Variability in Mg / Ca in Larger Benthic Foraminifera: Implications for Paleo-proxy

    Science.gov (United States)

    Singh, A.; Saraswati, P. K.; Pande, K.; Sanyal, P.

    2015-12-01

    The reports of inter-species variability to intra-test heterogeneity in Mg/Ca in several species of foraminifera have raised question about its use in estimation of seawater temperatures and necessitate field and culture studies to verify it for species from different habitats. In this study, we attempt to investigate if Mg/Ca in larger benthic foraminifera (LBF) could be a potential proxy of seawater temperatures for shallow marine carbonates. The samples were collected in different seasons from coral reef at Akajima (Okinawa, Japan). The Ca and Mg of 13 species of LBF and small benthic foraminifera from the same season were determined to examine variation in Mg/Ca among the species calcified under presumably the same temperature and salinity conditions. We also analyzed Amphistegina lessoni from different seasons for Ca, Mg and δ18O to determine variation in Mg/Ca with temperature and see how the two proxies of temperatures, Mg/Ca and δ18O, correlate in the same species. The species cluster about two distinctly separated Mg/Ca values. The first group comprising species of Amphistegina, Gypsina, Ammonia and Elphidium have relatively lower Mg/Ca, varying from 30 to 45 mmol/mol. The second group, having average Mg/Ca ranging from ~110 to 170 mmol/mol, includes species of Schlumbergerella, Baculogypsinoides, Baculogypsina, Heterostegina, Operculina, Calcarina, Amphisorus, Alveolinella and Poroeponides. The result suggests large interspecies variability implying vital effect in foraminiferal Mg/Ca. There is no distinct difference in Mg/Ca values between porcelaneous and hyaline types or symbiont-bearing and symbiont-free types. In Amphistegina lessoni the variation in Mg/Ca between individuals of the same season is as large as variation across the seasons. There is no correlation between Mg/Ca and seawater temperature. Lack of correlation between Mg/Ca and δ18O further suggests that Mg/Ca in the species is not primarily controlled by temperature.

  14. Assessment tools for urban catchments: developing biological indicators based on benthic macroinvertebrates

    Science.gov (United States)

    Purcell, A.H.; Bressler, D.W.; Paul, M.J.; Barbour, M.T.; Rankin, E.T.; Carter, J.L.; Resh, V.H.

    2009-01-01

    Biological indicators, particularly benthic macroinvertebrates, are widely used and effective measures of the impact of urbanization on stream ecosystems. A multimetric biological index of urbanization was developed using a large benthic macroinvertebrate dataset (n = 1,835) from the Baltimore, Maryland, metropolitan area and then validated with datasets from Cleveland, Ohio (n = 79); San Jose, California (n = 85); and a different subset of the Baltimore data (n = 85). The biological metrics used to develop the multimetric index were selected using several criteria and were required to represent ecological attributes of macroinvertebrate assemblages including taxonomic composition and richness (number of taxa in the insect orders of Ephemeroptera, Plecoptera, and Trichoptera), functional feeding group (number of taxa designated as filterers), and habit (percent of individuals which cling to the substrate). Quantile regression was used to select metrics and characterize the relationship between the final biological index and an urban gradient (composed of population density, road density, and urban land use). Although more complex biological indices exist, this simplified multimetric index showed a consistent relationship between biological indicators and urban conditions (as measured by quantile regression) in three climatic regions of the United States and can serve as an assessment tool for environmental managers to prioritize urban stream sites for restoration and protection.

  15. 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....

  16. Roles of epiphytes associated with macroalgae in benthic food web of a eutrophic coastal lagoon

    Science.gov (United States)

    Zheng, Xinqing; Huang, Lingfeng; Lin, Rongcheng; Du, Jianguo

    2015-11-01

    Macroalgae perform a significant function in the trophic dynamics in many coastal lagoons, and conventionally, they are the key trophic base that fuels the overall aquatic food web. However, few studies have considered the trophic contribution of epiphytes that attach to macroalgae in the diet of benthic primary consumers or their contribution to the trophic base of the aquatic food web. In this study, macrobenthic invertebrate biomass was combined with multiple-isotope-mixing models to distinguish the trophic importance of macroalgae and their associated epiphytic assemblages in the benthic food web during Ulva lactuca bloom in the Yundang Lagoon, a eutrophic coastal lagoon in Xiamen, China. Amphipods primarily dominated the zoobenthos, with the biomass varied from 40.9 g/m2 in January to 283.9 g/m2 in March. They mainly fed on U. lactuca and its associated epiphytes, which jointly contributed more than 60% to amphipod diets, but species-specific feeding habits were exhibited among amphipods. Using the zoobenthos biomass as a weighting factor, the contribution of U. lactuca and its epiphytes to total benthic communities during U. lactuca bloom exceeded 65%.The epiphytes were clearly utilized more than U. lactuca, with a median contribution ranging from 48.5% in January to 66.6% in March. Our findings demonstrate the trophic importance of the epiphytes in macroalgae-based coastal habitats, as found in many seagrass beds. Therefore, we propose that further food web studies of macroalgae-based ecosystems should pay greater attention to the role of epiphytes.

  17. Benthic foraminifera as biostratigraphical and paleoecological indicators:An example from Oligo-Miocene deposits in the SW of Zagros basin, Iran

    Institute of Scientific and Technical Information of China (English)

    Asghar Roozpeykar; Iraj Maghfouri Moghaddam

    2016-01-01

    The Asmari Formation is a predominantly carbonate lithostratigraphic unit that outcrops in the Zagros Basin. Micropaleontological studies of the Asmari Formation in the Dehdasht area led to the identifi-cation of 51 species of foraminifera taxa. Among the foraminifera, Nummulites cf. vascus, Operculin sp., Operculina complanata, Eulepidina dilatata, Eulepidina elephantine, Ditrupa sp., Miogypsina sp., Elphidium sp. 14, and Borelis melo curdica are the most important. The Lepidocyclina-Operculina-Ditrupa assemblage zone represents the RupelianeChattian age. The Aquitanian age is also defined by co-occurrence of Miogypsina sp. and Elphidium sp. 14, and finally, the first occurrence of Borelis melo curdica represents the Burdigalian. Based on faunal assemblages, the following paleoenvironmental settings are determined for the deposition of the study section: (1) the deep, offshore settings in the aphotic zone dominated by pelagic and small benthic foraminifera;(2) the low energy, turbid and low light parts of the oligophotic zone characterized by large and flat lepidocyclinids (Eulepidina) and Nummulitidae;(3) the low turbidity, deeper part of the inner ramp dominated by Miogypsinoides, Neorotalia, Lepidocyclina, Operculina and Archias; (4) the shallow, marginal marine environment exposed to salinity fluctuations (short-term salinity fluctuations or fully marine conditions) dominated by small benthic Foraminifera (Ammonia and Elphidium); (5) highly translucent, shallowest part of the inner ramp dominated by representatives of Borelis, Meandropsina and Peneroplis. The biotic assemblages represent warm tropical waters with oligotrophic to slightly mesotrophic conditions.

  18. 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...

  19. Prediction of benthic community structure from environmental variables in a soft-sediment tidal basin (North Sea)

    Science.gov (United States)

    Puls, W.; van Bernem, K.-H.; Eppel, D.; Kapitza, H.; Pleskachevsky, A.; Riethmüller, R.; Vaessen, B.

    2012-09-01

    The relationship between benthos data and environmental data in 308 samples collected from the intertidal zone of the Hörnum tidal basin (German Wadden Sea) was analyzed. The environmental variables were current velocity, wave action, emersion time (all of which were obtained from a 2-year simulation with a numerical model) and four sediment grain-size parameters. A grouping of sample stations into five benthos clusters showed a large-scale (>1 km) zoning of benthic assemblages on the tidal flats. The zoning varied with the distance from the shore. Three sample applications were examined to test the predictability of the benthic community structure based on environmental variables. In each application, the dataset was spatially partitioned into a training set and a test set. Predictions of benthic community structure in the test sets were attempted using a multinomial logistic regression model. Applying hydrodynamic predictors, the model performed significantly better than it did when sediment predictors were applied. The accuracy of model predictions, given by Cohen's kappa, varied between 0.14 and 0.49. The model results were consistent with independently attained evidence of the important role of physical factors in Wadden Sea tidal flat ecology.

  20. The response of stream fish to local and reach-scale variation in the occurrence of a benthic aquatic macrophyte

    Science.gov (United States)

    Argentina, J.E.; Freeman, Mary C.; Freeman, B.J.

    2010-01-01

    The aquatic macrophyte Podostemum ceratophyllum has been shown to increase stream productivity, abundance and biomass of benthic invertebrates, and local occurrences of some stream fishes. However, experimental evidence that fishes preferentially associate with Podostemum is lacking, and the value of Podostemum as a predictor of stream fish assemblage composition has not been studied. We conducted two short-term (2 week), small-scale (36 m2) experimental manipulations of Podostemum cover in the Conasauga River (Georgia and Tennessee, U.S.), and found higher abundances of benthic insectivorous fishes in patches with augmented (>80%) compared to reduced (7%) Podostemum cover. In an observational study, we quantified associations among percent cover of Podostemum, fish species richness, land cover, shoal length and base-flow turbidity at 20 randomly selected shoals from a 39-km reach that spanned a gradient of decreasing forest land cover.Richness of all fish species and of lotic fishes peaked in the centre of the study reach, and richness was weakly correlated with predictor variables. Occupancy models for individual species also indicated that longitudinal position was a strong covariate for 13 of 19 species examined, with little support that Podostemum cover influenced occupancy. Local associations may reflect choices by benthic fishes to utilise Podostemum, whereas downstream decline in fish species richness and Podostemum cover may reflect altered capacity of the system to support native species. Published 2009. This article is a US Government work and is in the public domain in the USA.

  1. Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the southwest Pacific

    Science.gov (United States)

    Pascher, K. M.; Hollis, C. J.; Bohaty, S. M.; Cortese, G.; McKay, R. M.; Seebeck, H.; Suzuki, N.; Chiba, K.

    2015-12-01

    The long-term cooling trend from middle to late Eocene was punctuated by several large-scale climate perturbations that culminated in a shift to "icehouse" climates at the Eocene-Oligocene transition. We present radiolarian micro-fossil assemblage and foraminiferal oxygen and carbon stable isotope data from Deep Sea Drilling Project (DSDP) sites 277, 280, 281, and 283 and Ocean Drilling Project (ODP) Site 1172 to identify significant oceanographic changes in the southwest Pacific through this climate transition (~ 40-30 Ma). We find that the Middle Eocene Climatic Optimum at ~ 40 Ma, which is truncated but identified by a negative shift in foraminiferal δ18O values at Site 277, is associated with a small increase in radiolarian taxa with low-latitude affinities (5 % of total fauna). In the early late Eocene at ~ 37 Ma, a positive oxygen isotope shift at Site 277 is correlated with the Priabonian Oxygen Isotope Maximum (PrOM). Radiolarian abundance, diversity, and preservation increase within this cooling event at Site 277 at the same time as diatom abundance. A negative δ18O excursion above the PrOM is correlated with a late Eocene warming event (~ 36.4 Ma). Radiolarian abundance and diversity decline within this event and taxa with low-latitude affinities reappear. Apart from this short-lived warming event, the PrOM and latest Eocene radiolarian assemblages are characterised by abundant high-latitude taxa. High-latitude taxa are also abundant during the late Eocene and early Oligocene (~ 38-30 Ma) at DSDP sites 280, 281, 283 and 1172 and are associated with very high diatom abundance. We therefore infer a northward expansion of high-latitude radiolarian taxa onto the Campbell Plateau in the latest Eocene. In the early Oligocene there is an overall decrease in radiolarian abundance and diversity at Site 277, and diatoms are scarce. These data indicate that, once the Antarctic Circumpolar Current was established in the early Oligocene (~ 30 Ma), a frontal system

  2. Selective zircon accumulation in a new benthic foraminifer, Psammophaga zirconia, sp. nov.

    Science.gov (United States)

    Sabbatini, A; Negri, A; Bartolini, A; Morigi, C; Boudouma, O; Dinelli, E; Florindo, F; Galeazzi, R; Holzmann, M; Lurcock, P C; Massaccesi, L; Pawlowski, J; Rocchi, S

    2016-07-01

    Benthic foraminifera are single-celled eukaryotes that make a protective organic, agglutinated or calcareous test. Some agglutinated, single-chambered taxa, including Psammophaga Arnold, 1982, retain mineral particles in their cytoplasm, but the selective mechanism of accumulation is not clear. Here, we report the ability of a foraminiferal species to select and accumulate zircons and other heavy minerals in their cytoplasm. In particular, the use of Scanning Electron Microscope coupled with an Energy Dispersive X-ray microanalysis system (SEM-EDS) enabled a representative overview of the mineral diversity and showed that the analysed Psammophaga zirconia sp. nov. individuals contained dominantly crystals of zircon (51%), titanium oxides (27%), and ilmenite (11%) along with minor magnetite and other minerals. The studied specimens occur in the shallow central Adriatic Sea where the sediment has a content of zircon below 1% and of other heavy minerals below 4%. For that reason we hypothesize that: (i) P. zirconia may be able to chemically select minerals, specifically zircon and rutile; (ii) the chemical mechanism allowing the selection is based on electrostatic interaction, and it could work also for agglutinated foraminifera (whether for ingestion, like Xenophyophores, or incorporation in the test as in many other described taxa). In particular, this aptitude for high preferential uptake and differential ingestion or retention of zircon is reported here for the first time, together with the selection of other heavy minerals already described in members of the genus Psammophaga. They are generally counted among early foraminifera, constructing a morphologically simple test with a single chamber. Our molecular phylogenetic study confirms that P. zirconia is a new species, genetically distinctive from other Psammophaga, and occurs in the Adriatic as well as in the Black Sea. PMID:27001345

  3. Effect of oxygen manipulations on benthic foraminifera: A preliminary experiment

    Digital Repository Service at National Institute of Oceanography (India)

    Panchang, R.; Nigam, R.; Linshy, V.; Rana, S.S.; Ingole, B.S.

    to changed oxygen conditions. After a fortnight, the experimental cores were sub-sectioned and analyzed for their live foraminiferal content. This data was compared with background field data obtained from the non-experimental core. The data indicate that any...

  4. Progress in Late Cretaceous planktonic foraminiferal stable isotope paleoecology and implications for paleoceanographic reconstructions

    Science.gov (United States)

    Petrizzo, Maria Rose; Falzoni, Francesca; Huber, Brian T.; MacLeod, Kenneth G.

    2015-04-01

    Paleoecological preferences proposed for Cretaceous planktonic foraminiferal taxa have traditionally been based on morphological analogies with depth-stratified modern species, on biofacies comparison in continental margin and deepwater settings, and limited oxygen and carbon stable isotope data. These studies concluded that large-sized, keeled and heavily calcified planktonic foraminifera generally lived at deeper levels in the surface waters than small-sized, thinner-walled non-keeled species. Stable isotope data have been used to infer information on paleotemperature, paleoceanography and paleoproductivity of ancient oceans and constrain biological paleo-activities (i.e. photosymbiosis and respiration) of fossil species. These studies have suggested that the depth-distribution model based on analogy with modern taxa might not be fully applicable for Cretaceous species, and found particularly 13C-enriched values in some Maastrichtian multiserial taxa that have been related to the activity of photosymbionts. We have collected about 1500 δ18O and δ13C species-specific analyses on glassy preserved planktonic foraminifera from Tanzania (Tanzania Drilling Project TDP sites 23, 28 and 32) and well-preserved planktonic foraminifera from other mid-low latitude localities (Shatsky Rise, northwestern Pacific Ocean, ODP Leg 198 Hole 1210B; Exmouth Plateau, eastern Indian Ocean, ODP Leg 122, Hole 762C; Eratosthenes Seamount, eastern Mediterranean, ODP Leg 160, Hole 967E; Blake Nose, central Atlantic Ocean, ODP Leg 171B, holes 1050C and 1052E) to investigate Late Cretaceous species paleoecological preferences, life strategies and depth distribution in the surface water column. Our results indicates that several large-sized (> 500 μm) double-keeled species belonging to the genera Dicarinella, Marginotruncana and Contusotruncana, generally interpreted as deep to thermocline dwellers, instead occupied shallow/warm layers of the water column, whilst not all biserial species

  5. Mercury-Pollution Induction of Intracellular Lipid Accumulation and Lysosomal Compartment Amplification in the Benthic Foraminifer Ammonia parkinsoniana.

    Science.gov (United States)

    Frontalini, Fabrizio; Curzi, Davide; Cesarini, Erica; Canonico, Barbara; Giordano, Francesco M; De Matteis, Rita; Bernhard, Joan M; Pieretti, Nadia; Gu, Baohua; Eskelsen, Jeremy R; Jubb, Aaron M; Zhao, Linduo; Pierce, Eric M; Gobbi, Pietro; Papa, Stefano; Coccioni, Rodolfo

    2016-01-01

    Heavy metals such as mercury (Hg) pose a significant health hazard through bioaccumulation and biomagnification. By penetrating cell membranes, heavy metal ions may lead to pathological conditions. Here we examined the responses of Ammonia parkinsoniana, a benthic foraminiferan, to different concentrations of Hg in the artificial sea water. Confocal images of untreated and treated specimens using fluorescent probes (Nile Red and Acridine Orange) provided an opportunity for visualizing the intracellular lipid accumulation and acidic compartment regulation. With increased Hg over time, we observed an increased number of lipid droplets, which may have acted as a detoxifying organelle where Hg is sequestered and biologically inactivated. Further, Hg seems to promote the proliferation of lysosomes both in terms of number and dimension that, at the highest level of Hg, resulted in cell death. We report, for the first time, the presence of Hg within the foraminiferal cell: at the basal part of pores, in the organic linings of the foramen/septa, and as cytoplasmic accumulations. PMID:27603511

  6. A bioassessment of lakes in the Athabasca Oil Sands Region, Alberta, using benthic macroinvertebrates

    Directory of Open Access Journals (Sweden)

    Keith M. SOMERS

    2010-08-01

    Full Text Available Emissions of sulphur oxides, nitrogen oxides and other pollutants have increased in the Athabasca Oil Sands Region (AOSR in Alberta, Canada. Atmospheric pollutants impact aquatic communities through a number of processes, but due to a lack of regional monitoring programs potential biological impacts have not been assessed. In this study, a bioassessment was conducted using approaches borrowed from a variety of protocols to establish a baseline dataset, determine appropriate methodologies, and to assess the current impact of emissions on benthic macroinvertebrate (BMI communities in the AOSR. As a result, 32 lakes, including 5 test lakes located in a modelled high deposition region, were sampled for water chemistry and BMI. The Reference Condition Approach (RCA was used because a baseline dataset does not exist and data were evaluated using three separate statistical techniques. All of the statistical methods used: One Sample T-Tests, Multivariate Analysis of Variance (MANOVA and Test Site Analysis (TSA, showed that BMI assemblages in test lakes differed from BMI assemblages in reference lakes. Traditional statistics classified all 5 test lakes as "significantly impaired" whereas TSA identified 3 of the 5 test lakes as only potentially impaired and 2 lakes were in "reference condition". The variability in lake attributes present challenges in interpreting BMI data and establishing an accurate biomonitoring program in the AOSR which need to be addressed in future assessment studies.

  7. Dramatic shifts in benthic microbial eukaryote communities following the Deepwater Horizon oil spill.

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    Holly M Bik

    Full Text Available Benthic habitats harbour a significant (yet unexplored diversity of microscopic eukaryote taxa, including metazoan phyla, protists, algae and fungi. These groups are thought to underpin ecosystem functioning across diverse marine environments. Coastal marine habitats in the Gulf of Mexico experienced visible, heavy impacts following the Deepwater Horizon oil spill in 2010, yet our scant knowledge of prior eukaryotic biodiversity has precluded a thorough assessment of this disturbance. Using a marker gene and morphological approach, we present an intensive evaluation of microbial eukaryote communities prior to and following oiling around heavily impacted shorelines. Our results show significant changes in community structure, with pre-spill assemblages of diverse Metazoa giving way to dominant fungal communities in post-spill sediments. Post-spill fungal taxa exhibit low richness and are characterized by an abundance of known hydrocarbon-degrading genera, compared to prior communities that contained smaller and more diverse fungal assemblages. Comparative taxonomic data from nematodes further suggests drastic impacts; while pre-spill samples exhibit high richness and evenness of genera, post-spill communities contain mainly predatory and scavenger taxa alongside an abundance of juveniles. Based on this community analysis, our data suggest considerable (hidden initial impacts across Gulf beaches may be ongoing, despite the disappearance of visible surface oil in the region.

  8. Further Water Column Evidence for Complexity in Planktonic Foraminiferal Mg/Ca: Challenges for Better Understanding the Paleotemperature Tracer

    Science.gov (United States)

    Mortyn, P.; Martinez-Boti, M. A.; Vance, D.

    2006-12-01

    The paleoceanographic community has witnessed an enormous increase in the application of planktonic foraminiferal Mg/Ca thermometry in recent years, based on the apparent exponential relationship of this tracer with respect to temperature (T). Despite the broad application of the technique, however, calibrations based on modern plankton tow material are rare. While recent refinements have been made with core-top, culture, and sediment trap calibration methods, only plankton tows offer a discrete-depth view from the shallow surface ocean habitat of the foraminifera. Six years ago we presented N. Atlantic plankton tow data to address this problem, and showed that water column foraminiferal Mg/Ca was elevated (compared to predicted values), scattered and unrelated (exponential or otherwise) to T, a controversial result due to concerns about potential contamination unique to this sample set. We now present new plankton tow data from the NE Pacific, with shallower samples treated with no risk of potentially similar contamination. This data also display little T- dependence, corroborating our earlier results to some degree, and further illustrating the need for understanding this tracer system better. Our California margin foraminiferal samples consist of Globigerina bulloides, Neogloboquadrina pachyderma (dextral), and Orbulina universa collected from shallow (low-temperature ashing to remove organic matter, and therefore do not pose the same risk for random Mg contamination related to the precipitation of Mg-oxides. They are also much more depth-restricted (~60m vs.~800m maximum collection depth). Furthermore, the samples have also been cleaned according to conventional methods, but with particular care taken to remove organic matter (more rigorous oxidative step in the cleaning procedure). As sediment trap, core-top, and culture calibrations of this tracer have shown clearer relationships to T, these discrete-depth water column results from the actual surface ocean

  9. Linking environmental forcing and trophic supply to benthic communities in the Vercelli Seamount area (Tyrrhenian Sea.

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    Anabella Covazzi Harriague

    Full Text Available Seamounts and their influence on the surrounding environment are currently being extensively debated but, surprisingly, scant information is available for the Mediterranean area. Furthermore, although the deep Tyrrhenian Sea is characterised by a complex bottom morphology and peculiar hydrodynamic features, which would suggest a variable influence on the benthic domain, few studies have been carried out there, especially for soft-bottom macrofaunal assemblages. In order to fill this gap, the structure of the meio-and macrofaunal assemblages of the Vercelli Seamount and the surrounding deep area (northern Tyrrhenian Sea - western Mediterranean were studied in relation to environmental features. Sediment was collected with a box-corer from the seamount summit and flanks and at two far-field sites in spring 2009, in order to analyse the metazoan communities, the sediment texture and the sedimentary organic matter. At the summit station, the heterogeneity of the habitat, the shallowness of the site and the higher trophic supply (water column phytopigments and macroalgal detritus, for instance supported a very rich macrofaunal community, with high abundance, biomass and diversity. In fact, its trophic features resembled those observed in coastal environments next to seagrass meadows. At the flank and far-field stations, sediment heterogeneity and depth especially influenced the meiofaunal distribution. From a trophic point of view, the low content of the valuable sedimentary proteins that was found confirmed the general oligotrophy of the Tyrrhenian Sea, and exerted a limiting influence on the abundance and biomass of the assemblages. In this scenario, the rather refractory sedimentary carbohydrates became a food source for metazoans, which increased their abundance and biomass at the stations where the hydrolytic-enzyme-mediated turnover of carbohydrates was faster, highlighting high lability.

  10. Environmental variations in a semi-enclosed embayment (Amvrakikos Gulf, Greece – reconstructions based on benthic foraminifera abundance and lipid biomarker pattern

    Directory of Open Access Journals (Sweden)

    E. Kaberi

    2012-06-01

    Full Text Available The evolution of environmental changes during the last decades and the impact on the living biomass in the western part of Amvrakikos Gulf was investigated using abundances of benthic foraminifera and lipid biomarker concentrations. These proxies indicated that the gulf has dramatically changed due to eutrophication. Eutrophication has led to a higher productivity, a higher bacterial biomass, shifts towards opportunistic and tolerant benthic foraminifera species (e.g. B. elongata, N. turgida, T. agglutinans, A. tepida and a lower benthic species density. Close to the Preveza Straits (connection between the gulf and the Ionian Sea, the benthic assemblages appeared to be less productive and more diversified under more oxygenated conditions. Sea grass meadows largely contributed to the organic matter at this sampling site. Isorenieratane, chlorobactane and lycopane together with oxygen monitoring data indicated that anoxic (and partly euxinic conditions prevailed seasonally throughout the western part of the gulf with more severe hypoxia towards the east. Increased surface water temperatures have led to a higher stratification, which reduced oxygen resupply to bottom waters. These developments are reasons for mass mortality events and ecosystem decline observed in Amvrakikos Gulf.

  11. Carbon flow and trophic structure of an Antarctic coastal benthic community as determined by δ 13C and δ 15N

    Science.gov (United States)

    Gillies, C. L.; Stark, J. S.; Johnstone, G. J.; Smith, S. D. A.

    2012-01-01

    Stable isotopes of carbon and nitrogen were used to determine the different carbon pathways and trophic assemblages amongst coastal benthic fauna of the Windmill Islands, East Antarctica. Macroalgae, pelagic POM, sediment POM and sea ice POM had well-separated δ 13C signatures, which ranged from -36.75‰ for the red alga Phyllophora antarctica, to -10.35‰ for sea ice POM. Consumers were also well separated by δ 13C, ranging from -21.42‰ for the holothurian Staurocucumis sp. up to -7.47‰ for the urchin Sterechinus neumayeri. Analysis of δ 13C and δ 15N revealed distinct groups for suspension feeders, grazer/herbivores and deposit feeders, whilst predators and predator/scavengers showed less grouping. Consumers spanned a δ 15N range of 8.71‰, equivalent to four trophic levels, although δ 15N ratios amongst consumers were continuous, rather than grouped into discrete trophic levels. The study has built a trophic model for the Windmill Islands and summarises three main carbon pathways utilised by the benthos: (1) pelagic POM; (2) macroalgae/epiphytic/benthic diatoms and (3) sediment POM/benthic diatoms. The movement of carbon within the coastal benthic community of the Windmill Islands is considered complex, and stable isotopes of carbon and nitrogen were valuable tools in determining specific feeding guilds and in tracing carbon flow, particularly amongst lower-order consumers.

  12. Land Use Influences Niche Size and the Assimilation of Resources by Benthic Macroinvertebrates in Tropical Headwater Streams.

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    Diego Marcel Parreira de Castro

    Full Text Available It is well recognized that assemblage structure of stream macroinvertebrates changes with alterations in catchment or local land use. Our objective was to understand how the trophic ecology of benthic macroinvertebrate assemblages responds to land use changes in tropical streams. We used the isotope methodology to assess how energy flow and trophic relations among macroinvertebrates were affected in environments affected by different land uses (natural cover, pasture, sugar cane plantation. Macroinvertebrates were sampled and categorized into functional feeding groups, and available trophic resources were sampled and evaluated for the isotopic composition of 13C and 15N along streams located in the Cerrado (neotropical savanna. Streams altered by pasture or sugar cane had wider and more overlapped trophic niches, which corresponded to more generalist feeding habits. In contrast, trophic groups in streams with native vegetation had narrower trophic niches with smaller overlaps, suggesting greater specialization. Pasture sites had greater ranges of resources exploited, indicating higher trophic diversity than sites with natural cover and sugar cane plantation. We conclude that agricultural land uses appears to alter the food base and shift macroinvertebrate assemblages towards more generalist feeding behaviors and greater overlap of the trophic niches.

  13. Land Use Influences Niche Size and the Assimilation of Resources by Benthic Macroinvertebrates in Tropical Headwater Streams

    Science.gov (United States)

    Parreira de Castro, Diego Marcel; Reis de Carvalho, Débora; Pompeu, Paulo dos Santos; Moreira, Marcelo Zacharias; Nardoto, Gabriela Bielefeld; Callisto, Marcos

    2016-01-01

    It is well recognized that assemblage structure of stream macroinvertebrates changes with alterations in catchment or local land use. Our objective was to understand how the trophic ecology of benthic macroinvertebrate assemblages responds to land use changes in tropical streams. We used the isotope methodology to assess how energy flow and trophic relations among macroinvertebrates were affected in environments affected by different land uses (natural cover, pasture, sugar cane plantation). Macroinvertebrates were sampled and categorized into functional feeding groups, and available trophic resources were sampled and evaluated for the isotopic composition of 13C and 15N along streams located in the Cerrado (neotropical savanna). Streams altered by pasture or sugar cane had wider and more overlapped trophic niches, which corresponded to more generalist feeding habits. In contrast, trophic groups in streams with native vegetation had narrower trophic niches with smaller overlaps, suggesting greater specialization. Pasture sites had greater ranges of resources exploited, indicating higher trophic diversity than sites with natural cover and sugar cane plantation. We conclude that agricultural land uses appears to alter the food base and shift macroinvertebrate assemblages towards more generalist feeding behaviors and greater overlap of the trophic niches. PMID:26934113

  14. Abyssal hills - hidden source of increased habitat heterogeneity, benthic megafaunal biomass and diversity in the deep sea

    Science.gov (United States)

    Durden, Jennifer M.; Bett, Brian J.; Jones, Daniel O. B.; Huvenne, Veerle A. I.; Ruhl, Henry A.

    2015-09-01

    Abyssal hills are the most abundant landform on Earth, yet the ecological impact of the resulting habitat heterogeneity on the wider abyss is largely unexplored. Topographic features are known to influence food availability and the sedimentary environment in other deep-sea habitats, in turn affecting the species assemblage and biomass. To assess this spatial variation, benthic assemblages and environmental conditions were compared at four hill and four plain sites at the Porcupine Abyssal Plain. Here we show that differences in megabenthic communities on abyssal hills and the adjacent plain are related to environmental conditions, which may be caused by local topography and hydrodynamics. Although these hills may receive similar particulate organic carbon flux (food supply from the surface ocean) to the adjacent plain, they differ significantly in depth, slope, and sediment particle size distribution. We found that megafaunal biomass was significantly greater on the hills (mean 13.45 g m-2, 95% confidence interval 9.25-19.36 g m-2) than the plain (4.34 g m-2, 95% CI 2.08-8.27 g m-2; ANOVA F(1, 6) = 23.8, p local sedimentary environment may be the mechanism driving these assemblage differences. Since the ecological heterogeneity provided by hills in the abyss has been underappreciated, regional assessments of abyssal biological heterogeneity and diversity may be considerably higher than previously thought.

  15. Land Use Influences Niche Size and the Assimilation of Resources by Benthic Macroinvertebrates in Tropical Headwater Streams.

    Science.gov (United States)

    Parreira de Castro, Diego Marcel; Reis de Carvalho, Débora; Pompeu, Paulo dos Santos; Moreira, Marcelo Zacharias; Nardoto, Gabriela Bielefeld; Callisto, Marcos

    2016-01-01

    It is well recognized that assemblage structure of stream macroinvertebrates changes with alterations in catchment or local land use. Our objective was to understand how the trophic ecology of benthic macroinvertebrate assemblages responds to land use changes in tropical streams. We used the isotope methodology to assess how energy flow and trophic relations among macroinvertebrates were affected in environments affected by different land uses (natural cover, pasture, sugar cane plantation). Macroinvertebrates were sampled and categorized into functional feeding groups, and available trophic resources were sampled and evaluated for the isotopic composition of 13C and 15N along streams located in the Cerrado (neotropical savanna). Streams altered by pasture or sugar cane had wider and more overlapped trophic niches, which corresponded to more generalist feeding habits. In contrast, trophic groups in streams with native vegetation had narrower trophic niches with smaller overlaps, suggesting greater specialization. Pasture sites had greater ranges of resources exploited, indicating higher trophic diversity than sites with natural cover and sugar cane plantation. We conclude that agricultural land uses appears to alter the food base and shift macroinvertebrate assemblages towards more generalist feeding behaviors and greater overlap of the trophic niches. PMID:26934113

  16. The role of benthic biofilm production in the mediation of silicon cycling in the Severn Estuary, UK

    Science.gov (United States)

    Welsby, H. J.; Hendry, K. R.; Perkins, R. G.

    2016-07-01

    The biological mediation of benthic biogenic silica (BBSi) by the diatom-dominated biofilms on the intertidal mudflats of the Severn Estuary (UK) was assessed in situ under different environmental conditions using measurements of productive biomass (chlorophyll a), photosynthetic activity of undisturbed microalgal assemblages, benthic biogenic silica (BBSi) and benthic dissolved silica (BDSi). We show low BBSi standing stocks in the mudflats compared to other European estuaries, under both warmer summer conditions (0.6%) and colder winter conditions (0.5%). Dissolved forms of Si (BDSi) dominated the estuary, with significantly higher concentrations during the sampled winter (22.6 ± 1.0 mg L-1) compared to the sampled summer (2.9 ± 0.5 mg L-1). Benthic algal biomass was higher under cold conditions compared to warmer conditions (24.0 ± 2.3 and 13.2 ± 1.9 mg g-1sed. dw., respectively), following reduced migratory behaviour in the winter increasing surficial biomass. Relative maximum Electron Transport Rate (rETRmax), used as a proxy for relative primary productivity, was higher under warm conditions (254.1 ± 20.1 rel. units) compared to cold conditions (116.0 ± 27.1 rel. units). The biofilms sampled in the summer biologically mediated Si by the productive, high light acclimated diatoms that were highly motile during fluorescence measurements, and exhibited migratory behaviour, which despite nutrient limitation, evidenced by low Fv/Fm, increased the accumulation of BBSi. The biofilms sampled in the winter that were subject to relatively colder temperatures, consisted of low light acclimated diatoms of reduced migratory capabilities, and induced NPQ that suppressed productivity, and mediated BBSi to a lesser extent. Environmental stresses reduced the biofilm biological mediation of Si, which controlled Si to a lesser extent compared to the high hydrodynamic energy increasing biofilm re-suspension and terrestrial/coastal inputs.

  17. 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

  18. 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.

  19. Benthic foraminifera as tools in interpretation of subsurface hydrocarbon fluid flow at Veslemøy High and Hola-Vesterålen areas of the Barents Sea.

    Science.gov (United States)

    Baranwal, Soma; Sauer, Simone; Knies, Jochen; Chand, Shyam; Jensen, Henning; Klug, Martin

    2014-05-01

    Relatively few studies have focused on high-latitude benthic foraminifera related to hydrocarbon seeps. In this study, we present micropaleontological data from 8 gravity cores from the Veslemøy High and 4 surface sediments (0-1cm) from Hola-Vesterålen, Norway. The study of hydrocarbon impregnation and its effect on benthic foraminfera was conducted on selected sediment samples from the calcium-rich Holocene sediments of the Veslemøy High. The assemblage of foraminifera have been identified from three regional clusters. Cluster I and II are dominated by benthic foraminifera Buccella, Cassidulina, Cibicides, Discopulvinulina, Epistominella, Pullenia and Trifarina. Cluster III is distinct with an elevated abundance of Cassidulina, Cibicides and Trifarina with significant (>5 %) occurrence of Nonionella and Uvigerina. There is no apparent dissolution on the preserved foraminifera. However, there can be differential dissolution or destruction of the more fragile (thinner-walled test) species like Epistominella, Nonionella or Pullenia while leaving behind over-represented species like Cibicides or Trifarina (both preferring coarse grained, high energy areas that can withstand permanent winnowing and redeposition) with higher preservation potential. Also, Cluster III is placed right over the underlying fault line with shallow seep-indications and thus the fluids released may have induced the dissolution of the fragile species. Moreover, the significant occurrence of benthic foraminifera Nonionella auris, and Uvigerina peregrina, in Holocene deposits of Cluster III may be indicative of environments influenced by hydrocarbon migration to the seafloor. Previous studies have reported active natural hydrocarbon seepage in the Hola area and the stable carbon and hydrogen isotopic composition of methane in the sediments suggests a predominantly thermogenic methane source. The seep-assemblage is composed of Cibicides (~60%), Cassidulina, Discanomalina, Textularia and

  20. Planktonic Foraminiferal Shell Weight Variability From The Cariaco Basin: Insights Into Carbon Dioxide Concentrations During The Last Glacial Period

    Science.gov (United States)

    McConnell, M. C.; Thunell, R.; Peterson, L. C.; Astor, Y.

    2010-12-01

    Here we present decadal scale records of sediment color reflectance, planktonic foraminiferal shell weight variability, and planktonic foraminiferal carbon isotope composition (δ13C) from the Cariaco Basin, Venezuela for the last glacial period (Marine Isotope Stage 3; ~32-55kyrBP) and demonstrate that the temporal variability in the records is associated with established stadial/interstadial climate oscillations. Sediment trap results from the Cariaco Basin suggest that the shell weight variability is driven, in part, by changes in the surface water carbonate ion concentration [CO3=]. Using the modern relationship between shell weight and [CO3=] for this location, we estimate down-core [CO3=] variability during MIS 3 in order to assess past changes in the surface seawater partial pressure of carbon dioxide (pCO2). This record also provides insight into past changes in pH. We find that the Cariaco Basin was a source for atmospheric carbon dioxide during this time interval and that pCO2 underwent large stadial/interstadial oscillations with higher values during interstadials than during stadials.

  1. Foraminiferal record of Holocene paleo-earthquakes on the subsiding south-western Poverty Bay coastline, New Zealand

    International Nuclear Information System (INIS)

    Foraminiferal faunas in 29 short cores (maximum depth 7 m) of estuarine and coastal wetland sediment were used to reconstruct the middle-late Holocene (last 7 ka) elevational history on the southern shores of Poverty Bay, North Island, New Zealand. This coast is on the southwest side of a rapidly subsiding area beneath western Poverty Bay. Modern Analogue Technique paleo-elevation estimates based on fossil foraminiferal faunas indicate that the four study areas have gradual late Holocene (<3.5 ka) subsidence rates that increase from the southwest (mean c. 0.5 m ka--1) to northeast (mean c. 1.0 m ka-1). Only two rapid, possibly co-seismic, vertical displacement events are recognised: (1) c. 1.2 m of subsidence at 5.7 ± 0.4 ka (cal yr BP), which may have been generated by a subduction interface earthquake centred offshore and recorded in other published studies in northern Hawkes Bay, c. 35 km to the south; and (2) c. 1 m of uplift (relative sea-level fall) at c. 4.5 ± 0.3 ka, which might have been generated by rupture on an offshore upper plate fault that also uplifted coastal terraces at Pakarae and Mahia, 40 km to the north and south of the study area, or by rupture on the subduction interface penetrating beneath Poverty Bay. No sudden displacement events are recognised during the last 4 ka although subsidence, possibly aseismic, has continued. (author).

  2. Responses of foraminiferal isotopic variations at ODP Site 1143 in the southern South China Sea to orbital forcing

    Institute of Scientific and Technical Information of China (English)

    TIAN Jun; WANG Pinxian; CHENG Xinrong

    2004-01-01

    The foraminiferal δ18O and δ13C records for the past 5 Ma at ODP Site 1143 reveal the linear responses of the Plio-Pleistocene climatic changes in the southern South China Sea to orbital forcing at the obliquity and precession bands. The phase of the δ18O variations with the orbital forcing is opposite to that of the δ13C, which may be caused by the frequent El Nino events from the equatorial Pacific. The amplification of the Northern Hemisphere Ice Sheet at ~3.3 Ma probably affected the development of the 100-ka climatic cycles. Its further spreading may spur the 100-ka climatic cycle to become the dominant cycle in the late Pleistocene. The "MidPleistocene Transition" event has localized influence on the isotopic variations in the southern South China Sea. The foraminiferal δ13C records for the past 5 Ma at Site 1143 are highly coherent with the orbital forcing at the long eccentricity band, and lead the δ18O records at the shorter eccentricity band, highlighting the importance of the carbon cycle in the global climate change.

  3. Tools for the development of a benthic quality index for Italian lakes

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    Angelo SOLIMINI

    2006-02-01

    Full Text Available In this paper, we propose a methodology to develop a benthic quality index useful for Italian lakes. The existing data about benthic macroinvertebrates of the Italian lakes were collected over a period of 50 years, but only a few lakes such as the Maggiore and the Mergozzo have been intensely studied. Some large lakes such as Lake Como are still almost uninvestigated. In total, 570 benthic macroinvertebrate taxa were identified; of which 373 belong to Chironomidae and 85 to Oligochaeta. With the aim of relating environmental variables with macrobenthos assemblages, we carried out a canonical correlation analysis (CANON using a database that included 1060 sampling points. Both environmental (13 variables describing morphometry and hydrochemistry and biological data (57 taxa were available, but only taxa present in at least 10 samples were selected for data analysis. Three canonical variates were ecologically significant. The first one was correlated with conductivity, pH and alkalinity and accounted for 20% of the total variation. The second one was positively correlated with total phosphorus and N-NH4, and inversely with dissolved oxygen, and accounted for 18% of the total variation. The third one showed a direct correlation with maximum lake depth and volume and an inverse correlation with water temperature, and accounted for 17% of the total variation. A Trophic Status Index (TSI, based on the table 11 of the Italian Law 152/99 (without including chlorophyll, was calculated by ranking percent oxygen saturation, transparency and total phosphorus. TSI was used to test a Benthic Quality Index for Italian Lakes (BQIL which is proposed in the present paper. The algorithm considered three steps. First, the means of three variables were calculated: percent oxygen saturation, transparency and total phosphorus weighted by the taxa abundances. These values are interpreted as optimum for each taxon and used to assign an indicator weight (BQIW. Second

  4. A simplified methodology to approach the complexity of foraminiferal calcite oxygen-isotope data - model comparison

    Science.gov (United States)

    Roche, Didier; Waelbroeck, Claire

    2016-04-01

    Since the pioneering work of Epstein (Epstein et al., 1953), numerous calcite isotopic records from the ocean have been used to attempt reconstructing paleoclimatic information. Additional to the well known complexity brought by the fact that foraminiferal calcite records both temperature and isotopic composition of the surrounding oceanic waters, an additional effect for surface - dwelling foraminifers is the fact that two different species do not have the same habitat and may thus record different signals. This is obvious when comparing paleoclimatic records where different species have been measured for the isotopic composition of the calcite. The difference in habitat produces a three dimensional spatial complexity (a foraminifera living in preferred climatic conditions at a specific location, but also at a specific depth, sometimes far from the surface) but also a temporal uncertainty (foraminifers generally live for only a few weeks and their growth season may be evolving through time with climate change). While the different species habitats potentially contain a wealth of information that could be used to better understand the sequences of climate change, this has seldom been used in modeling studies, most models deriving calcite isotopic signal from surface and annual mean conditions (e.g. Roche et al., 2014). In the present work, we propose a reduced complexity approach to compute the calcite for several planktonic foraminifers from climate model simulations under pre-industrial conditions. We base our approach on simple functions describing the temperature dependence of the different species growth rates (Lombard et al., 2009) and on probability of presence based on the physical variables computed in the climate model. We present a comparison to available sediment traps and core tops data as a validation of the methodology, focusing on the possibility for future applicability towards inversion of the signal measured in oceanic sediment cores. References

  5. Modern and Cenozoic records of magnesium behaviour from foraminiferal Mg isotopes

    Directory of Open Access Journals (Sweden)

    P. A. E. Pogge von Strandmann

    2014-05-01

    Full Text Available Magnesium is an element critically involved in the carbon cycle, because weathering of Ca–Mg silicates removes atmospheric CO2 into rivers, and formation of Ca–Mg carbonates in the oceans removes carbon from the ocean–atmosphere system. Hence the Mg cycle holds the potential to provide valuable insights into Cenozoic climate-system history, and the shift during this time from a greenhouse to icehouse state. We present Mg isotope ratios for the past 40 Myr using planktic foraminifers as an archive. Modern foraminifera, which discriminate against elemental and isotopically heavy Mg during calcification, show no correlation between the Mg isotope composition (δ26Mg and temperature, Mg / Ca or other parameters such as carbonate saturation (Δ CO3. However, inter-species isotopic differences imply that only well-calibrated single species should be used for reconstruction of past seawater. Seawater δ26Mg inferred from the foraminiferal record decreased from ~ 0‰ at 15 Ma, to −0.83‰ at the present day, which coincides with increases in seawater lithium and oxygen isotope ratios. It strongly suggests that neither Mg concentrations nor isotope ratios are at steady-state in modern oceans, given its ~ 10 Myr residence time. From these data, we have developed a dynamic box model to understand and constrain changes in Mg sources to the oceans (rivers and Mg sinks (dolomitisation and hydrothermal alteration. Our estimates of seawater Mg concentrations through time are similar to those independently determined by pore waters and fluid inclusions. Modelling suggests that dolomite formation and the riverine Mg flux are the primary controls on the δ26Mg of seawater, while hydrothermal Mg removal and the δ26Mg of rivers are more minor controls. Using riverine flux and isotope ratios inferred from the 87Sr / 86Sr record, the modelled Mg removal by dolomite formation shows minima in the Oligocene and at the present day (with decreasing trends from 15

  6. 川西北二叠系栖霞组小有孔虫动物群%Non-fusulinid Foraminiferal Fauna from the Permian Chihsia Formation,Northwestern Sichuan Basin

    Institute of Scientific and Technical Information of China (English)

    张舟; 张廷山; 蓝光志

    2011-01-01

    川西北广元旺苍王家沟剖面二叠系栖霞组小有孔虫动物群由14属27种组成(含比较种、亚种而不含未定种),其中Globivalvulina属及Palaeotextularidae科的物种分异度最高,合计约占总种数的50%.在系统分类的基础上,建立了Globivalvulina组合,作为识别该区二叠纪最大海进时期的标志性动物群.通过对该剖面栖霞组小有孔虫动物群的研究,不仅丰富了四川盆地二叠纪有孔虫的资料,而且为川西北王家沟剖面栖霞组与华南其他地区同期地层的对比提供了更多生物方面的依据.%The Permian non-fusulinid foraminifers of the Chihsia Formation are collected from Wangjiagou section in Wangcang County, Northwestern Sichuan Basin. The Chihsia Formation of Wangjiagou section is a suit of medium-bedded to thick-bedded limestones, with thickness of about 108 meters. Based on the systematic study to the Chihsia Formation, 27 species of 14 genera (including conformis species and subspecies) of the non-fusulinid foraminiferal fauna have been recognized in the Wangjiagou section. The Globivalvulina assemblage is suggested as indicative fauna for recognition of the Permian largest transgressive period. The result of this study not only enriches the fossil database of Sichuan Basin, but also provides more palaeontological evidences for stratigraphic correlation in South China.

  7. Calcareous assemblages of the southeastern Mediterranean low-tide estuaries - Seasonal dynamics and paleo-environmental implications

    Science.gov (United States)

    Avnaim-Katav, Simona; Agnon, Amotz; Sivan, Dorit; Almogi-Labin, Ahuva

    2016-02-01

    The study of estuarine ecosystems is essential for protecting and reestablishing their threatened biota. In this research the spatio-temporal variations in the distribution patterns of foraminifera, ostracods and molluscs are analyzed in surficial sediments sampled in 2012/13 at six low-tide estuaries of the southeastern Mediterranean coast. Live assemblages are studied using multivariate statistical analyses to determine their ecological preferences and seasonal dynamics whereas the dead assemblages are used to establish a reference baseline for future paleoenvironmental reconstruction. The statistical analysis indicates that salinity, TOC and % carbonate are the main environmental factors explaining 60% of the cumulative variance and controlling the distribution pattern of the different brackish taxa encountered in these estuaries. The foraminifera Ammonia tepida and some miliolids (Quinqueloculina and Varidentella) inhabit most estuaries during summer when salinities of 13-18 psu and temperatures of 26-34 °C occur. At the Naaman stream the agglutinated species Birsteiniolla macrostoma and Trichohyalus aguayoi dominate the assemblage during autumn and winter, respectively when salinities of 3-7 psu and temperature of 18-24 °C prevail. High abundance of the monospecific assemblage of the ostracod Cyprideis torosa was encountered at the Tanninim year round in oligohaline water. The gastropod Heleobia phaeniciaca prefers living at the Naaman and Tanninim streams while Pyrgophorus sp., an invasive and low salinity species, continue colonizing more stream reaches along the Israeli coast. The dead assemblages are composed of high numbers of local and transported species. It includes post storm-surge sediments containing high numbers of inland fresh and brackish water species transported by the floods. Those are mixed with inner to mid-shelf benthic and planktonic foraminifera, ostracods and molluscs. Transportation of the marine organisms a few hundred of meters

  8. Diatom assemblage responses to changing environment in the conspicuously eutrophic Kiuruvesi lake route, central-eastern Finland

    Science.gov (United States)

    Tammelin, Mira; Kauppila, Tommi

    2016-04-01

    the three Kiuruvesi route lakes portrays different trajectories in each lake. The central basin has changed less than the upstream lakes. Two of the lakes have assemblage change trajectories that suggest increased nutrients, electrical conductivity, and pH. Unexpectedly, one of the upstream lakes shows an opposite trajectory, which might result from lowering water depth and improved living conditions for benthic diatoms.

  9. 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...

  10. 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...

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

    Directory of Open Access Journals (Sweden)

    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.

  12. Foraminiferal biostratigraphy of lignite mines of Kutch,India:Age of lignite and fossil vertebrates

    Institute of Scientific and Technical Information of China (English)

    Pratul; Kumar; Saraswati; Sonal; Khanolkar; Dalta; Surya; Narayana; Raju; Suryendu; Dutta; Santanu; Banerjee

    2014-01-01

    The lignite deposits of Kutch, India are stratigraphically referred to the Naredi Formation and considered to be Early Eocene in age. The biostratigraphy of the older mine at Panandhro and a newly opened mine at Matanomadh has constrained the upper age limit of lignite to the early Bartonian. Its lower age may extend to the late Lutetian. Temporally the formation of lignite corresponds to the warming event of the Middle Eocene and suggests a humid climate at the onset of the warming. The previous palynological studies have already suggested dominance of tropical angiospermic pollen. A diverse assemblage of fossil whales and other vertebrates, many of them supposedly the oldest representatives, were reported from Panandhro mine. These were initially assigned to the Early Eocene and later to the Lute? tian age. The present biostratigraphic study revises their age to the Early Bartonian.

  13. 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

  14. Evaluating the response of biological assemblages as potential indicators for restoration measures in an intermittent Mediterranean river.

    Science.gov (United States)

    Hughes, Samantha Jane; Santos, Jose; Ferreira, Teresa; Mendes, Ana

    2010-08-01

    Bioindicators are essential for detecting environmental degradation and for assessing the success of river restoration initiatives. River restoration projects require the identification of environmental and pressure gradients that affect the river system under study and the selection of suitable indicators to assess habitat quality before, during and after restoration. We assessed the response of benthic macroinvertebrates, fish, bird and macrophyte assemblages to environmental and pressure gradients from sites situated upstream and downstream of a cofferdam on the River Odelouca, an intermittent Mediterranean river in southwest Portugal. The Odelouca will be permanently dammed in 2010. Principal Component Analyses (PCA) of environmental and pressure variables revealed that most variance was explained by environmental factors that clearly separated sites upstream and downstream of the partially built cofferdam. The pressure gradient describing physical impacts to the banks and channel as a result of land use change was less distinct. Redundancy Analysis revealed significant levels of explained variance to species distribution patterns in relation to environmental and pressure variables for all 4 biological assemblages. Partial Redundancy analyses revealed high levels of redundancy for pH between groups and that the avifauna was best associated with pressures acting upon the system. Patterns in invertebrates and fish were associated with descriptors of habitat quality, although fish distribution patterns were affected by reduced connectivity. Procrustean and RELATE (Mantel test) analyses gave broadly similar results and supported these findings. We give suggestions on the suitability of key indicator groups such as benthic macroinvertebrates and endemic fish species to assess in stream habitat quality and appropriate restoration measures, such as the release of peak flow patterns that mimic intermittent Mediterranean systems to combat habitat fragmentation and

  15. Impact of extreme oxygen consumption by pollutants on macroinvertebrate assemblages in plain rivers of the Ziya River Basin, north China.

    Science.gov (United States)

    Ding, Yuekui; Rong, Nan; Shan, Baoqing

    2016-07-01

    The aim of the study was to estimate the impact of oxygen depletion on macroinvertebrate community structure in benthic space. Macroinvertebrate assemblages and potential of dissolved oxygen (DO) consumption were investigated simultaneously in the plain rivers of the Ziya River Basin. The degree of DO depletion was represented by sediment oxygen demand (SOD) and DO, chemical oxygen demand (CODCr), and ammonia nitrogen (NH4 (+)-N) in the overlying water. The results showed an all-around hypoxia environment formed, and the values of DO, SOD, CODCr, and NH4 (+)-N were separately 0.11-4.03 mg L(-1), 0.41-2.60 g m(-2) day(-1), 27.50-410.00 mg L(-1), and 1.79-101.41 mg L(-1). There was an abnormal macroinvertebrate assemblage, and only 3 classes, Insecta, Gastropoda, and Oligochaeta, were found, which included 9 orders, 30 families, and 54 genera. The biodiversity was at a low level, and Shannon-Wiener index was 0.00-1.72. SOD, and NH4 (+)-N had major impact on the macroinvertebrate community, and the former had negative effect on most taxa, for instance, Nais, Branchiura, Paraleptophlebia, etc., which were sensitive or had a moderate-high tolerance to pollution. NH4 (+)-N had both positive and negative impacts on benthic animals, for instance, Dicrotendipes, Gomphus, Cricotopus, etc., for the former, and Procladius, Limnodrilus, Hippeutis, etc., for the latter. They all had a moderate-high tolerance to pollution. It is significant to improve DO condition and macroinvertebrate diversity in river harnessing and management. PMID:27048327

  16. Evaluating the Response of Biological Assemblages as Potential Indicators for Restoration Measures in an Intermittent Mediterranean River

    Science.gov (United States)

    Hughes, Samantha Jane; Santos, Jose; Ferreira, Teresa; Mendes, Ana

    2010-08-01

    Bioindicators are essential for detecting environmental degradation and for assessing the success of river restoration initiatives. River restoration projects require the identification of environmental and pressure gradients that affect the river system under study and the selection of suitable indicators to assess habitat quality before, during and after restoration. We assessed the response of benthic macroinvertebrates, fish, bird and macrophyte assemblages to environmental and pressure gradients from sites situated upstream and downstream of a cofferdam on the River Odelouca, an intermittent Mediterranean river in southwest Portugal. The Odelouca will be permanently dammed in 2010. Principal Component Analyses (PCA) of environmental and pressure variables revealed that most variance was explained by environmental factors that clearly separated sites upstream and downstream of the partially built cofferdam. The pressure gradient describing physical impacts to the banks and channel as a result of land use change was less distinct. Redundancy Analysis revealed significant levels of explained variance to species distribution patterns in relation to environmental and pressure variables for all 4 biological assemblages. Partial Redundancy analyses revealed high levels of redundancy for pH between groups and that the avifauna was best associated with pressures acting upon the system. Patterns in invertebrates and fish were associated with descriptors of habitat quality, although fish distribution patterns were affected by reduced connectivity. Procrustean and RELATE (Mantel test) analyses gave broadly similar results and supported these findings. We give suggestions on the suitability of key indicator groups such as benthic macroinvertebrates and endemic fish species to assess in stream habitat quality and appropriate restoration measures, such as the release of peak flow patterns that mimic intermittent Mediterranean systems to combat habitat fragmentation and

  17. Coral Reefs at the Northernmost Tip of Borneo: An Assessment of Scleractinian Species Richness Patterns and Benthic Reef Assemblages

    OpenAIRE

    Zarinah Waheed; Harald G J van Mil; Muhammad Ali Syed Hussein; Robecca Jumin; Bobita Golam Ahad; Hoeksema, Bert W.

    2015-01-01

    The coral reefs at the northernmost tip of Sabah, Borneo will be established under a marine protected area: the Tun Mustapha Park (TMP) by the end of 2015. This area is a passage where the Sulu Sea meets the South China Sea and it is situated at the border of the area of maximum marine biodiversity, the Coral Triangle. The TMP includes fringing and patch reefs established on a relatively shallow sea floor. Surveys were carried out to examine features of the coral reefs in terms of scleractini...

  18. Biogenic reefs affect multiple components of intertidal soft-bottom benthic assemblages: The Lanice conchilega case study

    OpenAIRE

    De Smet, B; D'Hondt, A.-S.; Verhelst, P.; Fournier, J.; Godet, L.; Desroy, N.; Rabaut, M.; Vincx, M.; Vanaverbeke, J.

    2015-01-01

    Biogenic reefs composed of the tube-building polychaete Lanice conchilega are important from a conservation point of view because they noticeably increase the biodiversity in otherwise species poor environments. However, up to now, little or no attention has been paid to the intertidal epi- and hyperbenthic communities associated with the reefs. Therefore, this is the first study which focuses on the effect of L. conchilega reefs on the entire bentho-pelagic community at two different locatio...

  19. Freshwater inflows and seasonal forcing strongly influence macrofaunal assemblages in Mediterranean coastal lagoons

    Science.gov (United States)

    Prado, Patricia; Caiola, Nuno; Ibáñez, Carles

    2014-06-01

    Coastal lagoons of the Ebro Delta (Catalonia, Spain) are part of the Ebro Delta Natural Park managed by regional government authorities. Coastal lagoons have persistently received freshwater inputs from the Ebro River from May to November that have altered their natural ecology and hydrological cycle. In this study, we evaluate the seasonal effect of contrasting salinity regimes (polyhaline in the Tancada lagoon, mesohaline in the Encanyissada and oligohaline in the Clot lagoon) on the composition, abundance, species richness, alpha diversity and biomass of benthic macrofauna communities, and we assess the relative contribution of local environmental variables to the observed patterns. Additional sampling was conducted in the largest lagoon (Encanyissada) in order to assess variability at lower spatial scale. At both spatial scales (i.e., among-lagoon and within-lagoon), species richness and diversity tended to increase at higher salinities, particularly in summer. At the assemblage level, significantly different groupings were also found among lagoons and among zones of the Encanyissada lagoon, with more distinctive differences also in summer. Environmental factors accounted for up to 56-60% of the variation in macrofaunal assemblages at both spatial scales, with salinity and temperature accounting for the largest contributions (approx. 14% and 10%, respectively), whereas biomass was mostly controlled by temperature and nutrients. Distinctive oxygen and organic matter levels across the lagoons were also associated with the freshwater influx and displayed significant contributions to observed patterns. Our study shows that the low salinity regime and/or other factors related to long-term inputs of freshwater shape the community of macrofauna within the lagoons, a central trophic resource for most of the local species of fish and aquatic birds. Restoration of these systems to their natural hydrological functioning without further inputs of freshwater and higher

  20. Benthic macroinvertebrates in Italian rice fields

    Directory of Open Access Journals (Sweden)

    Daniela Lupi

    2013-02-01

    Full Text Available Rice fields can be considered man-managed temporary wetlands. Five rice fields handled with different management strategies, their adjacent channels, and a spring were analysed by their benthic macroinvertebrate community to i evaluate the role of rice agroe- cosystem in biodiversity conservation; ii find indicator species which can be used to compare the ecological status of natural wetlands with rice agroecosystems; and iii find the influence of environmental variables on biodiversity. Different methods of data analysis with increasing degree of complexity – from diversity index up to sophisticated multivariate analysis – were used. The investigation provided a picture of benthic macroinvertebrates inhabiting rice agroecosystems where 173 taxa were identified, 89 of which detected in rice paddies. Among them, 4 phyla (Mollusca, Annelida, Nematomorpha, and Arthropoda, 8 classes (Bivalvia, Gastropoda, Oligochaeta, Hirudinea, Gordioida, Insecta, Branchiopoda, and Malacostraca, 24 orders, 68 families, 127 genera and 159 species have been found. Ten threatened and 3 invasive species were detected in the habitats examined. The information obtained by the different methods of data analysis allowed a more comprehensive view on the value of the components of rice agroecosystems. Data analyses highlighted significant differences between habitats (feeding channel and rice field, with higher diversity observed in channels, and emphasised the role of the water chemical-physical parameters. The period of water permanence in rice fields resulted to be only one of the factors influencing the community of benthic macroinvertebrates. The presence of rare/endangered species allowed characterising some stations, but it was less informative about management strategies in rice paddies because most of these species were absent in rice fields.

  1. A MORE COST-EFFECTIVE EMAP BENTHIC MACROFAUNAL SAMPLING PROTOCOL

    Science.gov (United States)

    Benthic macrofaunal sampling protocols in the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) are to collect 30 to 50 random benthic macrofauna [defined as animals retained on a 0.5 mm (East and Gulf Coasts, USA) or a 1.0 mm mesh siev...

  2. 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...

  3. 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.

  4. High macroalgal cover and low coral recruitment undermines the potential resilience of the world's southernmost coral reef assemblages

    KAUST Repository

    Hoey, Andrew

    2011-10-03

    Coral reefs are under increasing pressure from anthropogenic and climate-induced stressors. The ability of reefs to reassemble and regenerate after disturbances (i.e., resilience) is largely dependent on the capacity of herbivores to prevent macroalgal expansion, and the replenishment of coral populations through larval recruitment. Currently there is a paucity of this information for higher latitude, subtropical reefs. To assess the potential resilience of the benthic reef assemblages of Lord Howe Island (31°32?S, 159°04?E), the worlds\\' southernmost coral reef, we quantified the benthic composition, densities of juvenile corals (as a proxy for coral recruitment), and herbivorous fish communities. Despite some variation among habitats and sites, benthic communities were dominated by live scleractinian corals (mean cover 37.4%) and fleshy macroalgae (20.9%). Live coral cover was higher than in most other subtropical reefs and directly comparable to lower latitude tropical reefs. Juvenile coral densities (0.8 ind.m -2), however, were 5-200 times lower than those reported for tropical reefs. Overall, macroalgal cover was negatively related to the cover of live coral and the density of juvenile corals, but displayed no relationship with herbivorous fish biomass. The biomass of herbivorous fishes was relatively low (204 kg.ha -1), and in marked contrast to tropical reefs was dominated by macroalgal browsing species (84.1%) with relatively few grazing species. Despite their extremely low biomass, grazing fishes were positively related to both the density of juvenile corals and the cover of bare substrata, suggesting that they may enhance the recruitment of corals through the provision of suitable settlement sites. Although Lord Howe Islands\\' reefs are currently coral-dominated, the high macroalgal cover, coupled with limited coral recruitment and low coral growth rates suggest these reefs may be extremely susceptible to future disturbances. © 2011 Hoey et al.

  5. High macroalgal cover and low coral recruitment undermines the potential resilience of the world's southernmost coral reef assemblages.

    Directory of Open Access Journals (Sweden)

    Andrew S Hoey

    Full Text Available Coral reefs are under increasing pressure from anthropogenic and climate-induced stressors. The ability of reefs to reassemble and regenerate after disturbances (i.e., resilience is largely dependent on the capacity of herbivores to prevent macroalgal expansion, and the replenishment of coral populations through larval recruitment. Currently there is a paucity of this information for higher latitude, subtropical reefs. To assess the potential resilience of the benthic reef assemblages of Lord Howe Island (31°32'S, 159°04'E, the worlds' southernmost coral reef, we quantified the benthic composition, densities of juvenile corals (as a proxy for coral recruitment, and herbivorous fish communities. Despite some variation among habitats and sites, benthic communities were dominated by live scleractinian corals (mean cover 37.4% and fleshy macroalgae (20.9%. Live coral cover was higher than in most other subtropical reefs and directly comparable to lower latitude tropical reefs. Juvenile coral densities (0.8 ind.m(-2, however, were 5-200 times lower than those reported for tropical reefs. Overall, macroalgal cover was negatively related to the cover of live coral and the density of juvenile corals, but displayed no relationship with herbivorous fish biomass. The biomass of herbivorous fishes was relatively low (204 kg.ha(-1, and in marked contrast to tropical reefs was dominated by macroalgal browsing species (84.1% with relatively few grazing species. Despite their extremely low biomass, grazing fishes were positively related to both the density of juvenile corals and the cover of bare substrata, suggesting that they may enhance the recruitment of corals through the provision of suitable settlement sites. Although Lord Howe Islands' reefs are currently coral-dominated, the high macroalgal cover, coupled with limited coral recruitment and low coral growth rates suggest these reefs may be extremely susceptible to future disturbances.

  6. 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

  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. Benthic Macroinvertebrate Communities in Agriculturally Impaired Streams

    Directory of Open Access Journals (Sweden)

    Virginija Pliuraite

    2009-10-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE This work presents research into the taxonomic composition of macroinvertebrate communities in streams that are under the influence of agricultural pollution A total of 67 macroinvertebrate taxa (including 61 identified species belonging to 40 families have been identified in the explored streams. The greatest species richness is recorded for the Trichoptera (18 species/1 taxa and Mollusca (12 species. The molluscs Gyraulus albus, amphipods Gammarus pulex, caddisflies Hydropsyche pellucidula and oligochaetes are detected in all examined streams. There, the number of total benthic macroinvertebrate taxa is highly variable, ranging from 16 to 40. Results show that the examined streams depending on the benthic macroinvertebrate taxonomic composition and predominance of seperate macroinvertebrate groups undergo different pollution. Intolerant to pollution taxa such as Plecoptera, which are the most sensitive to pollution insects, have been found only in 5 of 12 examined streams and in low abundances. The richness and diversity of macrozoobenthos in some streams appear to respond to the water quality deterioration. The present study has found out that in the stream where the total macroinvertebrate taxa, EPT taxa richness are the lowest and a relative abundance of gatherers is the highest, the values of NH4-N, NO3-N, total N, PO4-P and total P in the stream water are the highest, too.

  9. 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.

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

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    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.

  11. 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

  12. Waves affect predator-prey interactions between fish and benthic invertebrates.

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    Gabel, Friederike; Stoll, Stefan; Fischer, Philipp; Pusch, Martin T; Garcia, Xavier-François

    2011-01-01

    Little is known about the effects of waves on predator-prey interactions in the littoral zones of freshwaters. We conducted a set of mesocosm experiments to study the differential effects of ship- and wind-induced waves on the foraging success of littoral fish on benthic invertebrates. Experiments were conducted in a wave tank with amphipods (Gammarus roeseli) as prey, and age-0 bream (Abramis brama, B0), age-0 and age-1 dace (Leuciscus leuciscus, D0 and D1) as predators. The number of gammarids suspended in the water column was higher in the wave treatments compared to a no-wave control treatment, especially during pulse waves mimicking ship-induced waves in comparison to continuous waves mimicking wind-induced waves. The resulting higher prey accessibility in the water column was differently exploited by the three types of predatory fish. D0 and D1 showed significantly higher foraging success in the pulse wave treatment than in the continuous and control treatments. The foraging success of D0 appears to be achieved more easily, since significantly higher swimming activity and more foraging attempts were recorded only for D1 under the wave treatments. In contrast, B0 consumed significantly fewer gammarids in both wave treatments than in the control. Hence, waves influenced predator-prey interactions differently depending on wave type and fish type. It is expected that regular exposure to ship-induced waves can alter littoral invertebrate and fish assemblages by increasing the predation risk for benthic invertebrates that are suspended in the water column, and by shifting fish community compositions towards species that benefit from waves. PMID:21104276

  13. Organic carbon cycling in abyssal benthic food chains: numerical simulations of bioenhancement by sewage sludge

    Science.gov (United States)

    Rowe, Gilbert T.

    1998-05-01

    The hypothetical bioenhancement of the endemic benthic biota on an oligotrophic abyssal plain by organic carbon has been investigated with mathematical simulation experiments. First, the responses of the biomass and respiration to seasonal variations in the rain of organic carbon (POC) have been simulated in a simplified benthic assemblage (sediment organic carbon, sediment-dwelling heterotrophs (bacteria, meiofauna, macrofauna and detritus feeding megafauna) and predatory megafauna), with no added organic matter. These calculations were based on measured standing stocks and respiration in the central North Pacific (5.8 km depth, 31°N Lat.×159°W Long.). The dynamic relationships in this natural "oligotrophic" food chain were then subjected to added inputs of organic carbon presumed to be in sewage sludge. Two examples are presented: a modest but continuous input of organic carbon (100 mg C m -2 d -1) and a year-long pulse of the same intensity. The continuous input forced the biomass and community respiration to steadily increase until they reached steady state in 15 years at values similar to those found on a typical continental shelf. The pulse exhibited the same pattern, but biomass and respiration returned to levels found under natural oligotrophic conditions several years after cessation of intensified carbon loading. The responses of the sediment community to added organic matter were validated using information from a deep-ocean sewage disposal site (DWD106) off the coast of New Jersey. The models are also used to illustrate an approach for estimating possible transfers of potentially toxic contaminants, such as total polycyclic aromatic hydrocarbons (tPAHs), in lipid-rich eggs. In the future it will be necessary to validate model results with deep-ocean in situ experiments.

  14. Distribution patterns of benthic diatoms during summer in the Niyang River, Tibet, China

    Institute of Scientific and Technical Information of China (English)

    PEI Guofeng; LIU Guoxiang

    2011-01-01

    The aim of this study was to investigate the distribution,density,community structure and biodiversity characteristics of benthic diatoms,and to analyze whether differences in species composition and abundance exist in different regions of the Niyang River,Tibet.Among the 157 taxa observed in 15 sampling sites in the main river and tributary,most were casual species (>100),the relative abundance of the genera Achnanthes and Fragilaria was 67% of the total relative abundance.Achnanthes minutissima was the most important species and dominated the whole river reaches (average relative abundance was 30%); the average diatom densities were 7.4× 105 cell/cm2 at all sites,and increased slowly from the upper section to downriver.The significant indicator taxa with higher relative abundance were Achnanthes biasolettiana (18.0%) and Fragilaria arcus (18.2%),Fragilaria capucina var.vaucheriae (31.2%),Fragilaria construens var.venter (11.3%) and Cymbella affinis (11.0%) in the upper,tributary and mid-river sections,respectively.Achnanthes minutissima was the most abundant species (56%) in the downriver section.Biodiversity indices showed a gradual decrease from the up- to down-river section,and dominant species were more abundant in the upper and mid-river sections than in the downriver section.A two-way indictor species analysis (TWINSPAN) of diatom composition clearly showed four different groups,namely the upper,mid,lower and tributary sections.Detrended correspondence analysis (DCA)supported the results of TW1NSPAN,and the characteristics of site distribution and species composition in the Niyang River supported the spatial structure of diatom assemblages.This study indicates that bio-assessment programs utilizing benthic diatoms could clearly benefit lotic water with regional stratification.

  15. Storm-event-transport of urban-use pesticides to streams likely impairs invertebrate assemblages.

    Science.gov (United States)

    Carpenter, Kurt D; Kuivila, Kathryn M; Hladik, Michelle L; Haluska, Tana; Cole, Michael B

    2016-06-01

    Insecticide use in urban areas results in the detection of these compounds in streams following stormwater runoff at concentrations likely to cause toxicity for stream invertebrates. In this 2013 study, stormwater runoff and streambed sediments were analyzed for 91 pesticides dissolved in water and 118 pesticides on sediment. Detections included 33 pesticides, including insecticides, fungicides, herbicides, degradates, and a synergist. Patterns in pesticide occurrence reveal transport of dissolved and sediment-bound pesticides, including pyrethroids, from upland areas through stormwater outfalls to receiving streams. Nearly all streams contained at least one insecticide at levels exceeding an aquatic-life benchmark, most often for bifenthrin and (or) fipronil. Multiple U.S. EPA benchmark or criterion exceedances occurred in 40 % of urban streams sampled. Bed sediment concentrations of bifenthrin were highly correlated (p insects and tolerant invertebrates such as amphipods, flatworms, nematodes, and oligochaetes dominated streams with relatively high concentrations of bifenthrin in bed sediments, whereas insects, sensitive invertebrates, and mayflies were much more abundant at sites with no or low bifenthrin concentrations. The abundance of sensitive invertebrates, % EPT, and select mayfly taxa were strongly negatively correlated with organic-carbon normalized bifenthrin concentrations in streambed sediments. Our findings from western Clackamas County, Oregon (USA), expand upon previous research demonstrating the transport of pesticides from urban landscapes and linking impaired benthic invertebrate assemblages in urban streams with exposure to pyrethroid insecticides. PMID:27170357

  16. 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

  17. Benthic indicators: From subjectivity to objectivity - Where is the line?

    Science.gov (United States)

    Dauvin, Jean-Claude; Bellan, Gérard; Bellan-Santini, Denise

    2010-07-01

    Over the last few years, the interest in using benthic indicators to assess marine environments has increased dramatically after a rather long period of relative stagnation, mostly due to the need to assess the status of coastal marine waters required by North American and European regulations. Numerous papers on this topic have been published in the domain of ecology, using a variety of different terms to refer to two categories of information: benthic species and the status of benthic communities. Nowadays, the abundant literature on these two categories makes it possible to comment on (1) the definition of the different terms used by benthic researchers, (2) the current increase of papers of rising complexity about benthic indicators, and (3) the subjectivity and objectivity involved in using benthic indicators. Faced with the increase in the number of methods, we recommend pragmatism and thus the transfer of simple methods to the research consultancies that are responsible for assessing benthic quality in numerous impact studies. Using certain procedures, such as the "sentinel species", the best professional judgement (BPJ) and taxonomic sufficiency (TS), should clearly be encouraged. PMID:20413132

  18. Anthropogenic disturbance and landscape patterns affect diversity patterns of aquatic benthic macroinvertebrates

    Science.gov (United States)

    Maloney, K.O.; Munguia, P.; Mitchell, R.M.

    2011-01-01

    Measures of species diversity are valuable tools for assessing ecosystem health. However, most assessments have addressed individual sites or regional taxon pools, with few comparisons of differences in assemblage composition within or among regions. We examined the effects of anthropogenic disturbance on local richness (?? diversity) and species turnover (?? diversity) of benthic macroinvertebrates in small streams within and between 2 ecoregions (Northern Piedmont vs Southeastern Plains ecoregions) of the Patuxent River basin (Maryland, USA). Regional species pools did not differ between ecoregions (Piedmont = 166 taxa, Plains = 162 taxa); however, local richness was lower in the Plains (mean = 17.4 taxa/stream) compared to the Piedmont (mean = 22.2 taxa/stream). When streams were categorized into disturbance classes (low, medium, high), local richness did not differ among categories for either region. However, at the entire Patuxent scale, local richness tended to decrease with % impervious cover in a watershed. Variation in species composition, analyzed with nonmetric multidimensional scaling (nMDS), differed significantly between Piedmont and Plains streams, and Plains streams had higher ?? diversity than Piedmont streams. When partitioned by disturbance category and region, ?? diversity differed only between the low-disturbance sites (Plains > Piedmont). Relationships between ?? diversity and environmental variables varied by region. ?? diversity was weakly negatively related to % row-crop cover in a watershed at the entire Patuxent scale. For the Piedmont region, ?? diversity tended to decrease with % forest, % pasture, and % row-crop cover in a watershed. Such negative relationships between ?? diversity and landuse variables indicate a possible homogenization of the assemblage. The incongruence between diversity measures and composition measures, together with differing effects of anthropogenic land use on ?? diversity in the 2 regions, emphasizes the need

  19. Southern Polar Front macroecological and biogeographical insights gained from benthic Ostracoda

    Science.gov (United States)

    Brandão, Simone N.; Vital, Helenice; Brandt, Angelika

    2014-10-01

    The Southern Ocean is one of the least known marine ecosystems on Earth, but the importance of understanding its biological and geochemical characteristics are urgent, because of the fast changing climate. Primary productivity is a key factor in ecosystem functioning, since this is the only process (except for the rare chemosynthesis) transforming solar energy into organic material, which can later be processed by all other living beings. Herein we investigate how primary productivity in the euphotic zone influences the biodiversity on the sea bed at abyssal depths, using Ostracoda (Crustacea) as a model. We also discuss the biogeographical pattern of the ostracod fauna. Samples collected from the Atlantic sector of the Southern Ocean close to the Southern Polar Front (i.e. ~51°S) during the SYSTCO II expedition are the basis for our analyses. For the statistical tests, we used samples collected with an epibenthic sledge, which has the advantages of sampling a far larger area than traditional gears (i.e. grabs and corers), and also collect Myodocopida and Halocyprida rarely recorded in ostracod studies. However, because of its large mesh size (i.e. 300 and 500 μm) the epibenthic sledge fails to recover small sized ostracods. Most benthic and benthopelagic ostracod species inhabiting the Southern Polar Front region are either endemic to the Southern Ocean or occur close to it. We conclude that ostracod assemblages living below areas of high primary productivity seem to be different to those below low productivity zones, but that assemblages living west of the Mid-Atlantic Ridge are not significantly distinct from the ones living to the east of this putative barrier.

  20. '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.

  1. Hudson Canyon benthic habitats characterization and mapping by integrated analysis of multidisciplinary data

    Science.gov (United States)

    Pierdomenico, Martina; Guida, Vincent G.; Rona, Peter A.; Macelloni, Leonardo; Scranton, Mary I.; Asper, Vernon; Diercks, Arne

    2013-04-01

    Hudson Canyon, about 180 km SE of New York City, is the largest eastern U.S. submarine canyon and is under consideration for HAPC (Habitat Area of Particular Concern) status, representing a fisheries and biodiversity hot spot. Interest in the area, within the perspective of ecosystem based management, marine spatial planning, habitat and species conservation, led to a joint project between NOAA Northeast Fisheries, U.S. Geological Survey (USGS), Mississippi Mineral Research Institute (MMRI), National Institute for Undersea Science and Technology (NIUST), Stony Brook and Rutgers Universities for the study of benthic habitats, that includes the assembly of existing data with newly collected ones: acoustic mapping, visual ground-truthing, hydrographic, sedimentological, and trawl data collections. Acoustic mapping, performed using AUV-mounted multibeam sonar, provided ultra-high resolution bathymetric and backscatter imagery (3m and 1m respectively) at all water depths for identification of geomorphological features and for the characterization of surficial sediments along the two thirds of the shelf portion of the canyon. Identification of benthic and demersal communities was accomplished by visual ground thruthing with underwater vehicle video and still cameras, and from trawl catch data. A CTD-rosette sampler provided water column salinity-temperature profiles and water samples for dissolved methane analysis in the vicinity of suspected bottom sources. Analysis of data revealed a complex of topographic structures and hydrological patterns that provide a wide range of physical habitats in a relatively small area. A mosaic of sandy and muddy substrates, gravel beds, rock outcrops, and semilithified clay outcrops host rich and varied faunal assemblages, including deepwater corals and sponge communities. Pockmark fields, occurring below 300 m depth, suggest that methane-based chemosynthetic carbonate deposition contributes to creation of specific hard bottom habitats

  2. Benthic ecology of the northeastern Chukchi Sea. Part II. Spatial variation of megafaunal community structure, 2009-2010

    Science.gov (United States)

    Blanchard, Arny L.; Parris, Carrie L.; Knowlton, Ann L.; Wade, Nicole R.

    2013-09-01

    Sources for spatial variability of benthic megafaunal communities in the northeastern Chukchi Sea are poorly documented and may include altered water circulation patterns, as noted for macrofauna. Spatial variability of megafauna was investigated by sampling with a plumb-staff beam trawl in three petroleum leases, the Klondike, Burger, and Statoil study areas, as part of a multi-disciplinary research program in the northeastern Chukchi Sea ecosystem. Trawling occurred during two sampling periods from 2009 and one in 2010 with a total of 81 trawls from 38 stations. A total of 99 discrete taxonomic categories were identified in 2009 and 2010 which were expanded to 239 taxa in the laboratory. Biomass in the three study areas ranged from ∼15,500 to ∼96,000 g 1000 m-2 and numerical density ranged from ∼8500 to ∼134,000 individuals 1000 m-2. Although the megabenthic species-assemblages in all three study areas were similar in composition, average biomass values were higher in Burger (ranging from ∼54,000 to ∼96,000 g 1000 m-2) where altered water circulation occurs, than in Klondike (ranging from ∼15,500 to ∼31,000 g 1000 m-2) or Statoil (∼15,000 g 1000 m-2). The brittle star Ophiura sarsi was the numerically dominant megafauna (70% of total biomass) followed by the snow crab Chionoecetes opilio (7% total biomass), as noted in prior investigations in the region. Biomass and density of benthic megafauna in this region reflected the high quantities of seasonal production reaching the benthos in the shallow waters of the Chukchi Sea. Differences in benthic communities among study areas were associated with variations in bottom-water temperature and latitude, and to a lesser extent, water depth and percent mud. We believe these associations arise from effects of topography on northward-flowing water, that create regions of slower currents, and consequently, higher organic deposition.

  3. Benthic ecology of the northeastern Chukchi Sea. Part I. Environmental characteristics and macrofaunal community structure, 2008-2010

    Science.gov (United States)

    Blanchard, Arny L.; Parris, Carrie L.; Knowlton, Ann L.; Wade, Nicole R.

    2013-09-01

    Spatial variations of processes driving macrofaunal distributions can arise from interactions among topographic features and oceanographic patterns, and are not understood at small scales in the northeastern Chukchi Sea. Benthic macrofauna and environmental characteristics were measured to determine factors driving macrofaunal distributions as part of a multidisciplinary environmental program in the northeastern Chukchi Sea from 2008 to 2010. Macrofauna were sampled in three study areas, named Klondike, Burger, and Statoil, with a van Veen grab at up to 82 stations each year, as well as an area where marine mammals were seen feeding. The macrofaunal assemblages in all study areas were similar in species-composition with deposit-feeding polychaetes (53% of density and of 26% biomass) and bivalves (15% of density and 52% of biomass) collectively the most prominent groups. Maldane sarsi dominated the polychaetes in terms of both density and biomass, while bivalves were numerically dominated by Ennucula tenuis, but their biomass was dominated by larger species such as Macoma calcarea and Astarte borealis. Exceptions occurred in the marine mammal feeding area that was dominated by amphipods (71% of density and 30% biomass). Average densities were higher in Burger than in Klondike or Statoil, while biomass values were similar between Burger and Statoil, and higher in these two study areas than in Klondike. Overall, the distributions, biomass and density of benthic macrofauna reflect the high volume of production reaching the seafloor in the shallow waters of the Chukchi Sea. Variations in community structure among study areas were correlated with water depth and bottom-water temperature. Short-term temporal differences in community structure covaried with interannual oceanographic variations that may have altered food availability, macrofaunal survival, or larval recruitment. Topographic control over circulation appears to be a primary driver in structuring benthic

  4. 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.

  5. Three dimensional morphological studies of Larger Benthic Foraminifera at the population level using micro computed tomography

    Science.gov (United States)

    Kinoshita, Shunichi; Eder, Wolfgang; Woeger, Julia; Hohenegger, Johann; Briguglio, Antonino; Ferrandez-Canadell, Carles

    2015-04-01

    Symbiont-bearing larger benthic Foraminifera (LBF) are long-living marine (at least 1 year), single-celled organisms with complex calcium carbonate shells. Their morphology has been intensively studied since the middle of the nineteenth century. This led to a broad spectrum of taxonomic results, important from biostratigraphy to ecology in shallow water tropical to warm temperate marine palaeo-environments. However, it was necessary for the traditional investigation methods to cut or destruct specimens for analysing the taxonomically important inner structures. X-ray micro-computed tomography (microCT) is one of the newest techniques used in morphological studies. The greatest advantage is the non-destructive acquisition of inner structures. Furthermore, the running improve of microCT scanners' hard- and software provides high resolution and short time scans well-suited for LBF. Three-dimensional imaging techniques allow to select and extract each chamber and to measure easily its volume, surface and several form parameters used for morphometric analyses. Thus, 3-dimensional visualisation of LBF-tests is a very big step forward from traditional morphology based on 2-dimensional data. The quantification of chamber form is a great opportunity to tackle LBF structures, architectures and the bauplan geometry. The micrometric digital resolution is the only way to solve many controversies in phylogeny and evolutionary trends of LBF. For the present study we used micro-computed tomography to easily investigate the chamber number of every specimen from statistically representative part of populations to estimate population dynamics. Samples of living individuals are collected at monthly intervals from fixed locations. Specific preparation allows to scan up to 35 specimens per scan within 2 hours and to obtain the complete digital dataset for each specimen of the population. MicroCT enables thus a fast and precise count of all chambers built by the foraminifer from its

  6. Morphogenetic role of F-actin meshwork in chamber formation: immunolabeling results from symbiont bearing benthic foraminifera

    Science.gov (United States)

    Tyszka, Jaroslaw; Raitzsch, Markus; Bijma, Jelle; Höher, Nicole; Bickmeyer, Ulf; Rivera-Ingraham, Georginia; Topa, Paweł; Kaczmarek, Karina; Mewes, Antje; Bowser, Samuel; Travis, Jeffrey

    2015-04-01

    Foraminifera are excellent tracers of palaeoceanographic conditions recorded in their shell (test) morphology and chemical composition. Understanding foraminiferal morphology controlled by chamberwise growth can be reduced to processes of chamber formation. However, little is known about how foraminifera control the shape of the chamber wall to be biosynthesized and precipitated. Searching for fundamental morphogenetic features involved in biomineralization, we focused on foraminifers, which belong to the class Globothalamea. The most critical condition to run experiments was to have convenient access to early stages of chamber formation in any species of cultured benthic foraminifers. We have tested small foraminifers collected from the tidal flats of the North Sea. All species, including Ammonia, Haynesina, and Elphidium, turned out to be unsuitable due to their reproduction seasonality and/or unpredictability. The problem was solved by using symbiont bearing Amphistegina lessonii cultured in small aquaria. In well treated cultures, such foraminifera often reproduce on a glass wall surface, serving as a continuous source of juveniles. They tend to regularly construct chambers. Another important point is that symbiont bearing foraminifers usually do not construct opaque protective cysts from detritus that disturb observations. All these features facilitate immunolabeling experiments observed under confocal microscopy. Therefore, for the first time, we managed to label cytoskeleton proteins during the chamber formation in Foraminifera. The results show that the shape of chamber is predefined by a meshwork of F-actin, which acts as a dynamic organic scaffold most likely responsible for distribution and docking of biomineralizing molecules (glycoproteins). The F-actin meshwork interacts with microtubules and all associated proteins, which are involved in the morphogenesis of biomineralized structures. Foraminifera, like other eukaryotic cells, can form active

  7. Benthic Communities of Low-Order Streams Affected by Acid Mine Drainages: A Case Study from Central Europe

    Directory of Open Access Journals (Sweden)

    Marek Svitok

    2014-05-01

    Full Text Available Only little attention has been paid to the impact of acid mine drainages (AMD on aquatic ecosystems in Central Europe. In this study, we investigate the physico-chemical properties of low-order streams and the response of benthic invertebrates to AMD pollution in the Banská Štiavnica mining region (Slovakia. The studied streams showed typical signs of mine drainage pollution: higher conductivity, elevated iron, aluminum, zinc and copper loads and accumulations of ferric precipitates. Electric conductivity correlated strongly with most of the investigated elements (weighted mean absolute correlation = 0.95 and, therefore, can be recommended as a good proxy indicator for rapid AMD pollution assessments. The diversity and composition of invertebrate assemblages was related to water chemistry. Taxa richness decreased significantly along an AMD-intensity gradient. While moderately affected sites supported relatively rich assemblages, the harshest environmental conditions (pH < 2.5 were typical for the presence of a limited number of very tolerant taxa, such as Oligochaeta and some Diptera (Limnophyes, Forcipomyiinae. The trophic guild structure correlated significantly with AMD chemistry, whereby predators completely disappeared under the most severe AMD conditions. We also provide a brief review of the AMD literature and outline the needs for future detailed studies involving functional descriptors of the impact of AMD on aquatic ecosystems.

  8. 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

  9. The effect of carbonate chemistry and light levels on calcification and photosynthesis in the larger benthic foraminifera Operculina ammonoides

    Science.gov (United States)

    Oron, Shai; Abramovich, Sigal; Evans, David; Erez, Jonathan

    2015-04-01

    We present data on metabolic measurements and growth experiments conducted on Operculina ammonoides, a symbiont bearing larger benthic foraminifera (LBF) of the family Nummulitidae, which is the closest living descendant of the Eocene Nummulites. The large size, the high abundance and wide distribution of Nummulitids and other LBF make them a vital archive for ancient and recent oceanic environments. LBF are also an important component of the ocean tropical and subtropical benthic ecosystem, where they have a significant contribution to primary production, and are major calcium carbonate producers. Their symbiosis, calcification physiology, and ecological response to environmental changes are poorly understood. The present study is part of an ongoing research effort focused on those topics. Calcification, respiration and symbiont photosynthesis were measured during long-term experiments that included manipulation of carbonate chemistry parameters and light levels. The experiments were done with large number of individuals (1500 in total) divided into incubation groups of 60-100. Diurnal and nocturnal data was obtained, along with cumulative incubations on a time span of a few days. The metabolic rates were estimated from measurements of dissolved oxygen, total alkalinity and pH before and after the incubations. This technique does not interfere with the experimental populations and allow a series of measurements to be performed on the same specimens. In all experiments, both for the diurnal cycles and for the long incubations, we observed significantly higher photosynthesis rates than respiration (positive O2 budget) for the holobiont. This oxygen excess has increased with light intensity, suggesting a significant growth of the symbionts within their host. Calcification was enhanced during the day compared to the night but did not increase with light intensity or with photosynthesis. In normal seawater, higher calcification rates were observed during the cumulative

  10. Larger Foraminifera from the Spermonde Archipelago (Sulawesi, Indonesia)

    OpenAIRE

    Troelstra, S. R.; Jonkers, H.M.; Rijk, de, J.

    1996-01-01

    A systematic description of the distributional patterns of larger symbiont-bearing benthic Foraminifera from the Spermonde Archipelago (Sulawesi, Indonesia) and their relation with local coral reef growth is presented. The larger Foraminiferal assemblages and diversity indices correspond with the diversity of Scleractinia and marine plants on the Spermonde platform. Our results indicate that the group is an excellent biomonitor for the health condition of recent coral reefs and a valuable too...

  11. How magnetics and granulometry of continental margin sediments reflect terrestrial and marine environments of South America and West Africa

    OpenAIRE

    Razik, Sebastian

    2014-01-01

    Continental margins are supplied by terrigenous clastic, as well as by biogenic marine sediments and, thus, act as natural archives for various environmental conditions. This thesis delineates sediment-distribution patterns off SE South America (20-55 deg. S) and NW Africa (14-17 deg. N) mainly based on rock-magnetic properties supplemented by clastic grain-size distributions, major-element concentrations, planktic and benthic foraminiferal assemblages, as well as stable-isotope signatures ob...

  12. Biostratigraphic and Environmental Analysis of the Upper Jurassic- Lower Cretaceous Carbonate Sequence in the Başoba Yayla Area (Trabzon, NE Turkey)

    OpenAIRE

    TASLI, Kemal; Özer, Erol

    1999-01-01

    In the Başoba Yayla (Trabzon, NE Turkey) area, which is located in the Eastern Pontides northern zone, platform carbonates were deposited during the Late Jurassic-Early Cretaceous time in environments varying from intertidal/ supratidal to outer shelf. The carbonate sequence begins with a thick dolomite unit of the Late Jurassic to Early Cretaceous age. The following unit is rich in benthic foraminifers and pelecypoda shells. The foraminiferal assemblage comprising Vercorsella laurentii/ca...

  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. 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 ...

  15. 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...

  16. Vieques, Puerto Rico Benthic Habitat Map - Accuracy Assessment Sites

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic habitat maps of the nearshore marine environment of Vieques, Puerto Rico were created by visual interpretation of remotely sensed imagery. The objective of...

  17. Coastal Bend Texas Benthic Habitat - San Antonio Bay 2007 Biotic

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  18. Coastal Bend Texas Benthic Habitat - Lower Laguna Madre 2004 Substrate

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  19. Coastal Bend Texas Benthic Habitat - Lower Laguna Madre 2004 Geodatabase

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  20. Coastal Bend Texas Benthic Habitat - Espiritu Santo Bay 2007 Geoform

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing and new digital multi-spectral imagery and create digital benthic...

  1. Coastal Bend Texas Benthic Habitat - San Antonio Bay 2007 Geoform

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  2. Coastal Bend Texas Benthic Habitat - San Antonio Bay 2007 Substrate

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  3. Coastal Bend Texas Benthic Habitat - Espiritu Santo Bay 2007 Geodatabase

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing and new digital multi-spectral imagery and create digital benthic...

  4. Coastal Bend Texas Benthic Habitat - Espiritu Santo Bay 2007 Biotic

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing and new digital multi-spectral imagery and create digital benthic...

  5. Coastal Bend Texas Benthic Habitat - Lower Laguna Madre 2004 Biotic

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  6. Coastal Bend Texas Benthic Habitat - Lower Laguna Madre 2004 Geoform

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  7. Coastal Bend Texas Benthic Habitat - Espiritu Santo Bay 2007 Substrate

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing and new digital multi-spectral imagery and create digital benthic...

  8. Coastal Bend Texas Benthic Habitat - San Antonio Bay 2007 Geodatabase

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  9. Vieques, Puerto Rico Benthic Habitat Map - Ground Validation Sites

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic habitat maps of the nearshore marine environment of Vieques, Puerto Rico were created by visual interpretation of remotely sensed imagery. The objective of...

  10. Shallow-water Benthic Habitats in Jobos Bay

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (<30m) benthic habitat maps of the nearshore marine environment of Jobos Bay, Puerto Rico were mapped and characterized using visual interpretation...

  11. Benthic grab data from October 1999 in Apalachicola Bay, Florida

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Apalachicola Bay National Estuarine Research Reserve and the NOAA Office for Coastal Management worked together to map benthic habitats within Apalachicola Bay,...

  12. Evidence for complete denitrification in a benthic foraminifer

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Langezaal, Alexandra; Ingvardsen, Signe; Schmid, Markus; Derksen, Jan W.M.; Op den Camp, Huup; Pina-Ochoa, Elisa; Eriksson, Susanne; Nielsen, Lars Peter; Revsbech, Niels Peter; Cedhagen, Tomas; van der Zwaan, Gilbert J.

    2006-01-01

    Benthic foraminifera are unicellular eukaryotes found abundantly in many types of marine sediments. Many species survive and possibly reproduce in anoxic habitats1, but sustainable anaerobic metabolism has not been previously described. Here we demonstrate that the foraminifer Globobulimina pseud...

  13. WASP7 BENTHIC ALGAE - MODEL THEORY AND USER'S GUIDE

    Science.gov (United States)

    The standard WASP7 eutrophication module includes nitrogen and phosphorus cycling, dissolved oxygen-organic matter interactions, and phytoplankton kinetics. In many shallow streams and rivers, however, the attached algae (benthic algae, or periphyton, attached to submerged substr...

  14. Estimation of sediment properties during benthic impact experiments

    Digital Repository Service at National Institute of Oceanography (India)

    Yamazaki, T.; Sharma, R.

    Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans...

  15. Northeast Puerto Rico and Culebra Island - Benthic Habitat Map 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This benthic habitat map was created from a semi-automated habitat mapping process, using a combination of bathymetry, satellite imagery, aerial imagery and...

  16. Coastal Bend Texas Benthic Habitat Mapping Redfish Bay 2004 Substrate

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  17. Coastal Bend Texas Benthic Habitat Mapping Aransas Bay 2004 Substrate

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  18. Atlantic Deep-Water Canyons (Benthic Landers) 2013

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Each benthic lander contains a programmable sediment trap which can take 12 monthly samples, plus instruments to record temperature, salinity, dissolved oxygen,...

  19. USVI Land-Based Threat to Benthic Habitats

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set describes the potential threat of sediment delivery and land-based sources of pollution to benthic habitats. This dataset is derived from NOAA's...

  20. Coastal Bend Texas Benthic Habitat Mapping Patchy Shapefile Map

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  1. Metal incorporation by benthic fauna: relationships to sediment inventory

    International Nuclear Information System (INIS)

    A radionuclide addition experiment was conducted in a large-scale experimental mesocosm to study the behaviour and fate of trace metals in a coastal marine environment. Twelve radionuclides (7Be, 109Cd, 134Cs, 58Co, 60Co, 51Cr, 59Fe, 54Mn, 203Hg, 233Pa, 113Sn, and 65Zn) were added and their concentrations in benthic organisms and sediments were measured during the following nine months. The ability of benthic organisms to concentrate radionuclides was related to the vertical distribution and feeding behaviour of the organisms. Surface living fauna incorporated more radionuclides than deeper fauna. Calculations of total annual radionuclide incorporation by benthic fauna indicated that meiofauna incorporated a similar amount of the labelled metals as the macrofauna, even though the latter have a larger standing stock biomass. These calculations suggest that benthic metazoan fauna can annually cycle from 1% (Sn) to nearly 50% (Cd) of the amount of added radionuclides measured in sediments. (author)

  2. BENTHIC MACROFAUNA-HABITAT ASSOCIATIONS IN WILLAPA BAY, WASHINGTON, USA

    Science.gov (United States)

    Estuary-wide benthic macrofauna-habitat associations in Willapa Bay, Washington, United States, were determined for 4 habitats (eelgrass [Zostera marina], Atlantic cordgrass [Spartina alterniflora], mud shrimp [Upogebia pugettensis], ghost shrimp [Neotrypaea californiensis]) in 1...

  3. BENTHIC MACROFAUNA-HABITAT RELATIONSHIPS IN WILLAPA BAY, WA

    Science.gov (United States)

    Benthic macrofauna-habitat relationships were determined estuary-wide in Willapa Bay, WA for four intertidal habitats ((1) eelgrass, Zostera marina, (2) Atlantic cordgrass, Spartina alterniflora, (3) ghost shrimp, Neotrypaea californiensis, (4) mud shrimp, Upogebia pugettensis) i...

  4. Puerto Rico Land-Based Threat to Benthic Habitats

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set describes the potential threat of sediment delivery and land-based sources of pollution to benthic habitats. This dataset is derived from NOAA's...

  5. Shallow-Water Benthic Habitats of Southwest Puerto Rico

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (<30m) benthic habitat maps of the nearshore marine environment of two areas in Southwest Puerto Rico (PR), including the Guanica Bay/La Parguera...

  6. Photosynthesis and respiration of some marine benthic algae from Spitsbergen

    OpenAIRE

    Latala, Adam

    1990-01-01

    Light-photosynthesis curves for 9 species of benthic algae from the Hornsund fiord were determined. As a result of adaptation to the conditions in the Arctic, benthic algae from Spitsbergen have a low requirement of light. Saturation and compensation points are low and within a range typical for shadow-tolerant plants.The values for gas exchange rates indicate that Arctic algae have lower photosynthctic capacity than temperate species.

  7. Exploring Benthic Biodiversity Patterns and Hotspots on European Margin Slopes

    OpenAIRE

    Roberto Danovaro; Miquel Canals; Serge Heussner; Nikolaos Lampadariou; Ann Vanreusel

    2009-01-01

    There is increasing evidence that continental slope ecosystems represent one of the major repositories of benthic marine biodiversity. The enhanced levels of biodiversity along slopes are hypothesized to be a source of biodiversity for continental shelves and deeper basins. Continental margins are increasingly altered by human activities, but the consequences of these anthropogenic impacts on benthic biodiversity and ecosystem functioning are almost completely unknown. Thus, there is an urgen...

  8. Exploring benthic biodiversity patterns and hotspots on European margin slopes

    OpenAIRE

    Danovaro, R.; M. Canals; Gambi, C.; S. Heussner; Lampadariou, N.; Vanreusel, A.

    2009-01-01

    There is increasing evidence that continental slope ecosystems represent one of the major repositories of benthic marine biodiversity. The enhanced levels of biodiversity along slopes are hypothesized to be a source of biodiversity for continental shelves and deeper basins. Continental margins are increasingly altered by human activities, but the consequences of these anthropogenic impacts on benthic biodiversity and ecosystem functioning are almost completely unknown. Thus, there is an urgen...

  9. Live-dead agreement of benthic communities under pressure by chronic oil pollution in the Arabian Sea

    Science.gov (United States)

    Albano, Paolo G.; Tomašových, Adam; Stachowitsch, Michael; Filippova, Nadezhda; Steger, Jan; Zuschin, Martin

    2014-05-01

    Mismatch between the richness or species composition of a death assemblage (DA) and the local living assemblage (LA) is typically attributed to natural post-mortem processes, particularly preservational bias. Recent research, however, suggests that live-dead (LD) agreement is significantly lower in anthropogenically disturbed settings. This reflects the so-called "compositional inertia" of DAs to recent environmental change, i.e., DAs still capture earlier community states not affected by such disturbance. The inertia to changing ecological conditions should be particularly likely under conditions of anthropogenic modification because the rapidity of many human-driven changes is unprecedented in natural systems. Our research tests this hypothesis by evaluating the agreement between the LA and DA in benthic communities around the Zakum oil field in the Southern Arabian Sea, off the coast of the United Arab Emirates. This is an area of intense oil extraction, with almost 800 offshore oil and gas platforms and 25 major terminals, but no studies on the related impacts are widely available. This approach also sheds light on chronic pollution in tropical settings, an underrepresented topic in the literature. The size fraction between 2 and 5 mm was sorted for living molluscs and empty shells, which were then segregated to morphospecies and identified. The agreement was evaluated in terms of fidelity of species richness, evenness, and rank-order agreement. Compositional fidelity was also evaluated by multivariate analysis. The communities are dominated by bivalves. Polyplacophorans and scaphopods are occasionally present. Gastropod abundance is marginal compared to the bivalves, although their contribution is more significant when species diversity is taken into consideration. Moreover, the living assemblage in the studied size range was particularly poor in terms of species abundance.

  10. 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

  11. Structural and functional responses of benthic invertebrates to imidacloprid in outdoor stream mesocosms

    International Nuclear Information System (INIS)

    Structural and functional responses of a benthic macroinvertebrate assemblage to pulses of the insecticide imidacloprid were assessed in outdoor stream mesocosms. Imidacloprid pulses reduced invertebrate abundance and community diversity in imidacloprid-dosed streams compared to control streams. These results correlated well with effects of imidacloprid on leaf litter decomposition and feeding rates of Pteronarcys comstocki, a stonefly, in artificial streams. Reductions in oxygen consumption of stoneflies exposed to imidacloprid were also observed in laboratory experiments. Our findings suggest that leaf litter degradation and single species responses can be sensitive ecotoxicological endpoints that can be used as early warning indicators and biomonitoring tools for pesticide contamination. The data generated illustrates the value of mesocosm experiments in environmental assessment and how the consideration of functional and structural endpoints of natural communities together with in situ single species bioassays can improve the evaluation and prediction of pesticide effects on stream ecosystems. - Combining organism-level responses with community-level processes for the evaluation and prediction of pesticide effects on stream ecosystems.

  12. Fringing reefs exposed to different levels of eutrophication and sedimentation can support similar benthic communities

    International Nuclear Information System (INIS)

    Highlights: • We assess anthropogenic pressures on coral reef health. • We present a spatio-temporal survey of environmental parameters as bio-indicators. • Poor water quality (e.g. high turbidity and high sediments) was not correlated with lower coral cover. • Phytoplankton community size-composition and habitat stability were important predictors of coral reef health. - Abstract: Benthic communities are sensitive to anthropogenic disturbances which can result in changes in species assemblages. A spatio-temporal survey of environmental parameters was conducted over an 18-month period on four different fringing reefs of Moorea, French Polynesia, with unusual vs. frequent human pressures. This survey included assessment of biological, chemical, and physical parameters. First, the results showed a surprising lack of a seasonal trend, which was likely obscured by short-term variability in lagoons. More frequent sampling periods would likely improve the evaluation of a seasonal effect on biological and ecological processes. Second, the three reef habitats studied that were dominated by corals were highly stable, despite displaying antagonistic environmental conditions through eutrophication and sedimentation gradients, whereas the reef dominated by macroalgae was relatively unstable. Altogether, our data challenge the paradigm of labelling environmental parameters such as turbidity, sedimentation, and nutrient-richness as stress indicators

  13. Intertidal to subtidal distribution of benthic macrofauna in an estuarine beach of Babitonga Bay, southern Brazil

    Directory of Open Access Journals (Sweden)

    Paulo Roberto Pagliosa

    2006-03-01

    Full Text Available This paper reports on the spatial variation of a macrofaunal community along the intertidalsubtidal gradient of an estuarine beach located at the mouth of Babitonga Bay, in Southern Brazil. The fauna and sediment were sampled at 0, 5, 10, and 20 m depths in three transects. Differences in benthic assemblages among the depths were found to be significant and related to the major local processes of sediment changes. The analysis of taxa composition showed an impoverished community subject to wave action and erosionaccretion dynamics at landward stations (0 and 5 m depths. Seaward macrofauna (10 and 20 m depths inhabiting sediments with higher organic content and poorly-sorted sands were more diverse and numerically dominated by ophiuroids and by cirratulid (Tharyx sp. and maldanid (Clymenella brasiliensis polychaetes. A breakdown in the zonation patterns of environment and community was detected where sediments produced by a creek outlet enabled increasing stability and higher densities of the soft bottom anthozoa Edwardsia sp. and the polychaete Lumbrineris atlantica. Additionally, the sediments with an excessive amount of fine particles were densely colonized (mean of 22,400 individuals.m-2 by C. brasiliensis. The local sediment characteristics were related to maldanid sediment-reworking. The macrofaunal species compositions along the sandy beaches at the mouths of the southern Brazilian estuarine systems were compared.

  14. Recruitment and Succession in a Tropical Benthic Community in Response to In-Situ Ocean Acidification.

    Directory of Open Access Journals (Sweden)

    Elizabeth Derse Crook

    Full Text Available Ocean acidification is a pervasive threat to coral reef ecosystems, and our understanding of the ecological processes driving patterns in tropical benthic community development in conditions of acidification is limited. We deployed limestone recruitment tiles in low aragonite saturation (Ωarag waters during an in-situ field experiment at Puerto Morelos, Mexico, and compared them to tiles placed in control zones over a 14-month investigation. The early stages of succession showed relatively little difference in coverage of calcifying organisms between the low Ωarag and control zones. However, after 14 months of development, tiles from the low Ωarag zones had up to 70% less cover of calcifying organisms coincident with 42% more fleshy algae than the controls. The percent cover of biofilm and turf algae was also significantly greater in the low Ωarag zones, while the number of key grazing taxa remained constant. We hypothesize that fleshy algae have a competitive edge over the primary calcified space holders, coralline algae, and that acidification leads to altered competitive dynamics between various taxa. We suggest that as acidification impacts reefs in the future, there will be a shift in community assemblages away from upright and crustose coralline algae toward more fleshy algae and turf, established in the early stages of succession.

  15. Partially repeatable genetic basis of benthic adaptation in threespine sticklebacks.

    Science.gov (United States)

    Erickson, Priscilla A; Glazer, Andrew M; Killingbeck, Emily E; Agoglia, Rachel M; Baek, Jiyeon; Carsanaro, Sara M; Lee, Anthony M; Cleves, Phillip A; Schluter, Dolph; Miller, Craig T

    2016-04-01

    The extent to which convergent adaptation to similar ecological niches occurs by a predictable genetic basis remains a fundamental question in biology. Threespine stickleback fish have undergone an adaptive radiation in which ancestral oceanic populations repeatedly colonized and adapted to freshwater habitats. In multiple lakes in British Columbia, two different freshwater ecotypes have evolved: a deep-bodied benthic form adapted to forage near the lake substrate, and a narrow-bodied limnetic form adapted to forage in open water. Here, we use genome-wide linkage mapping in marine × benthic F2 genetic crosses to test the extent of shared genomic regions underlying benthic adaptation in three benthic populations. We identify at least 100 Quantitative Trait Loci (QTL) harboring genes influencing skeletal morphology. The majority of QTL (57%) are unique to one cross. However, four genomic regions affecting eight craniofacial and armor phenotypes are found in all three benthic populations. We find that QTL are clustered in the genome and overlapping QTL regions are enriched for genomic signatures of natural selection. These findings suggest that benthic adaptation has occurred via both parallel and nonparallel genetic changes. PMID:26947264

  16. Modelling benthic biophysical drivers of ecosystem structure and biogeochemical response

    Science.gov (United States)

    Stephens, Nicholas; Bruggeman, Jorn; Lessin, Gennadi; Allen, Icarus

    2016-04-01

    The fate of carbon deposited at the sea floor is ultimately decided by biophysical drivers that control the efficiency of remineralisation and timescale of carbon burial in sediments. Specifically, these drivers include bioturbation through ingestion and movement, burrow-flushing and sediment reworking, which enhance vertical particulate transport and solute diffusion. Unfortunately, these processes are rarely satisfactorily resolved in models. To address this, a benthic model that explicitly describes the vertical position of biology (e.g., habitats) and biogeochemical processes is presented that includes biological functionality and biogeochemical response capturing changes in ecosystem structure, benthic-pelagic fluxes and biodiversity on inter-annual timescales. This is demonstrated by the model's ability to reproduce temporal variability in benthic infauna, vertical pore water nutrients and pelagic-benthic solute fluxes compared to in-situ data. A key advance is the replacement of bulk parameterisation of bioturbation by explicit description of the bio-physical processes responsible. This permits direct comparison with observations and determination of key parameters in experiments. Crucially, the model resolves the two-way interaction between sediment biogeochemistry and ecology, allowing exploration of the benthic response to changing environmental conditions, the importance of infaunal functional traits in shaping benthic ecological structure and the feedback the resulting bio-physical processes exert on pore water nutrient profiles. The model is actively being used to understand shelf sea carbon cycling, the response of the benthos to climatic change, food provision and other societal benefits.

  17. Progress research report, 27 June, 1983, benthic invertebrate studies

    International Nuclear Information System (INIS)

    The benthic ecological research at site W-N for the Low Level Waste Ocean Disposal Program is oriented towards characterizing the invertebrate community associated with the seafloor and towards understanding the links within the benthic food web. Stomach analyses of benthic-feeding fishes reveal a varied diet of benthic and peloagio-benthic forms. From the trawl samples of megafauna, the basic community structure is similar to other deep-sea areas with echinoderms as the predominant forms. For the macrofauna, polychaete worms comprise the dominant taxonomic group. Very little is known about the fauna at area W-N on the species level. Such data will help answer the question of whether this community is characteristic of the continental slope base or is a transition between continentally-influenced communities and those in the central portion of ocean basins. Environmental differences within the area suggest that the benthic fauna should also vary in composition and abundance. 19 references, 7 figures, 5 tables

  18. Sensitivity of Coastal Environments and Wildlife to Spilled Oil: Upper Coast of Texas: BENTHIC (Benthic habitat polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains known locations of patchy and continuous seagrass and oyster reef habitat for the Upper Coast of Texas benthic habitat data. This data set...

  19. mkk_benthic_habitats - Benthic habitat of the coral reef ecosystem on the south shore of Molokai Hawaii.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A benthic habitat polygon coverage has been created of the coral reef ecosystem on the south shore of Moloka'i. Polygons were hand-digitized from visual...

  20. Linking benthic biodiversity and environmental conditions at the sea floor combining statistical and mechanistic modeling. Case study on the Black Sea's northwestern shelf.

    Science.gov (United States)

    Drion, Roxanne; Capet, Arthur; Gregoire, Marilaure

    2014-05-01

    benthic assemblages. A particular attention is given to the influence of seasonal hypoxia on benthic biotopes composition.

  1. Stable isotope ratios reveal food source of benthic fish and crustaceans along a gradient of trophic status in the East China Sea

    Science.gov (United States)

    Chang, Ni-Na; Shiao, Jen-Chieh; Gong, Gwo-Ching; Kao, Shuh-Ji; Hsieh, Chih-hao

    2014-08-01

    The East China Sea (ECS) receives large quantities of particulate organic matter (POM) and inorganic nutrients transported from the Changjiang (Yangtze River), which have produced high productivity in the northwestern ECS. This study evaluated potential contributions of terrigenous POM (allochthonous food source) and nutrient-induced marine production (autochthonous source) to the ECS benthic ecosystem by analyzing stable isotopic compositions of phytoplankton, zooplankton, benthic crustaceans and fish. Benthic consumers exhibited δ13C values similar to those of their autochthonous food sources (i.e., phytoplankton and zooplankton), revealing their major reliance on marine production. In contrast, the δ13C values of benthic fish (-19.6‰ to -13.5‰) and crustaceans (-18.9‰ to -15.0‰) were much higher than that of terrigenous POM (-25.7‰), which generally accounted for less than 20% of the most fish diet. Phytoplankton and zooplankton generally exhibited higher δ13C values at eutrophic and highly productive inshore sites than at oligotrophic offshore sites. This enrichment of inshore δ13C values was mainly attributed to lower photosynthetic fractionation during algal blooms, an effect that was further enhanced during flood period of the Changjiang. The δ13C values of demersal fish assemblages were also significantly higher at inshore sites and decreased seaward. However, fish δ15N values and their estimated trophic levels showed relatively small spatial variation. The disproportionate variations in δ13C and δ15N values suggested that the enriched C isotopic signatures derived from an elevated δ13C baseline of the inshore food web instead of trophic enrichment of the isotopic ratios. The significantly positive correlations between concentrations of chlorophyll a and nutrients versus fish δ13C provided further evidence for the use of pelagic algal bloom materials by inshore consumers. The isotopic and oceanographic survey data suggested that

  2. Benthic algal vegetation in Isfjorden, Svalbard

    Directory of Open Access Journals (Sweden)

    Stein Fredriksen

    2015-08-01

    Full Text Available Benthic algal vegetation was investigated at 10 sites in Isfjorden, Svalbard. Five sites were visited during summer 2010 and five during summer 2012. Both the littoral and sublittoral vegetation were sampled, the littoral by hand-picking and use of a throwable rake and the sublittoral using a triangular dredge. A total of 88 different taxa were registered, comprising 17 Chlorophyta, 40 Ochrophyta, 30 Rhodophyta and the Xantophyceae Vaucheria sp. The green algae Ulvaria splendens (Ruprecht Vinogradova was recorded in Svalbard for the first time. Most of the sites consisted of hard bottom substrate, but one site, Kapp Wijk, consisted of loose-lying calcareous red algae (rhodoliths and had species not recorded elsewhere. The sublittoral at the other sites was dominated by kelp. Molecular analysis confirmed the presence of the red alga Ceramium virgatum and a dwarf form of the brown alga Fucus vesiculosus. This study provides a baseline for future studies investigating changes in the vegetation due to environmental changes.

  3. Response of benthic foraminifera to ocean acidification in their natural sediment environment: a long-term culturing experiment

    Science.gov (United States)

    Haynert, K.; Schönfeld, J.; Schiebel, R.; Wilson, B.; Thomsen, J.

    2014-03-01

    Calcifying foraminifera are expected to be endangered by ocean acidification; however, the response of a complete community kept in natural sediment and over multiple generations under controlled laboratory conditions has not been constrained to date. During 6 months of incubation, foraminiferal assemblages were kept and treated in natural sediment with pCO2-enriched seawater of 430, 907, 1865 and 3247 μatm pCO2. The fauna was dominated by Ammonia aomoriensis and Elphidium species, whereas agglutinated species were rare. After 6 months of incubation, pore water alkalinity was much higher in comparison to the overlying seawater. Consequently, the saturation state of Ωcalc was much higher in the sediment than in the water column in nearly all pCO2 treatments and remained close to saturation. As a result, the life cycle (population density, growth and reproduction) of living assemblages varied markedly during the experimental period, but was largely unaffected by the pCO2 treatments applied. According to the size-frequency distribution, we conclude that foraminifera start reproduction at a diameter of 250 μm. Mortality of living Ammonia aomoriensis was unaffected, whereas size of large and dead tests decreased with elevated pCO2 from 285 μm (pCO2 from 430 to 1865 μatm) to 258 μm (pCO2 3247 μatm). The total organic content of living Ammonia aomoriensis has been determined to be 4.3% of CaCO3 weight. Living individuals had a calcium carbonate production rate of 0.47 g m-2 a-1, whereas dead empty tests accumulated a rate of 0.27 g m-2 a-1. Although Ωcalc was close to 1, approximately 30% of the empty tests of Ammonia aomoriensis showed dissolution features at high pCO2 of 3247 μatm during the last 2 months of incubation. In contrast, tests of the subdominant species, Elphidium incertum, stayed intact. Our results emphasize that the sensitivity to ocean acidification of the endobenthic foraminifera Ammonia aomoriensis in their natural sediment habitat is much

  4. 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.

  5. Evaluation of I/Ca ratios in benthic foraminifera from the Peruvian oxygen minimum zone as proxy for redox conditions in the ambient water masses

    Science.gov (United States)

    Glock, N.; Liebetrau, V.; Eisenhauer, A.

    2014-12-01

    Tropical oxygen minimum zones (OMZs) are most important areas of oxygen depletion in today´s oceans and nutrient cycling in these regions has a large socio-economic impact because they account for about 17% of the global commercial fish catches(1). Possibly increasing magnitude and area of oxygen depletion in these regions, might endanger rich pelagic fish habitats in the future threatening the global marine food supply. By the use of a quantitative redox proxy in OMZs, reconstruction of the temporal variation in OMZ extension eventually providing information about past and future changes in oxygenation and the anthropogenic role in the recent trend of expanding OMZs(2). Recent work has shown that iodine/calcium (I/Ca) ratios in marine carbonates are a promising proxy for ambient oxygen concentration(3). Our study explores the correlation of I/Ca ratios in four benthic foraminiferal species (three calcitic, one aragonitic) from the Peruvian OMZ to bottom water oxygen concentrations ([O2]BW) and evaluates foraminiferal I/Ca ratios as a possible redox proxy for the ambient water masses. Our results show that all species have a positive trend in the I/Ca ratios as a function of [O2]BW. Only for the aragonitic species Hoeglundina elegans this trend is not significant. The highest significance has been found for Uvigerina striata (I/Ca = 0.032(±0.004).[O2]BW + 0.29(±0.03), R² = 0.61, F = 75, P issues which have to be considered. These "pitfalls" include: (i) the volatility of iodine in acidic solutions, (ii) a species dependency of the I/Ca-[O2]BW relationship which is either related to a strong vital effect or toa species dependency on the calcification depth within sediment, and (iii) the inter-test variability of I/Ca between different specimens from the same species and habitat. (1): FAO FishStat: Fisheries and aquaculture software. In: FAO Fisheries and Aquaculture Department[online]. Rome. Updated 28 Nov. 2013. (2): Stramma et al.: Expanding Oxygen

  6. Prey distribution, physical habitat features, and guild traits interact to produce contrasting shorebird assemblages among foraging patches.

    Directory of Open Access Journals (Sweden)

    Beth M VanDusen

    Full Text Available Worldwide declines in shorebird populations, driven largely by habitat loss and degradation, motivate environmental managers to preserve and restore the critical coastal habitats on which these birds depend. Effective habitat management requires an understanding of the factors that determine habitat use and value to shorebirds, extending from individuals to the entire community. While investigating the factors that influenced shorebird foraging distributions among neighboring intertidal sand flats, we built upon species-level understandings of individual-based, small-scale foraging decisions to develop more comprehensive guild- and community-level insights. We found that densities and community composition of foraging shorebirds varied substantially among elevations within some tidal flats and among five flats despite their proximity (all located within a 400-m stretch of natural, unmodified inlet shoreline. Non-dimensional multivariate analyses revealed that the changing composition of the shorebird community among flats and tidal elevations correlated significantly (ρ(s = 0.56 with the spatial structure of the benthic invertebrate prey community. Sediment grain-sizes affected shorebird community spatial patterns indirectly by influencing benthic macroinvertebrate community compositions. Furthermore, combining sediment and macroinvertebrate information produced a 27% increase in correlation (ρ(s = 0.71 with shorebird assemblage patterns over the correlation of the bird community with the macroinvertebrate community alone. Beyond its indirect effects acting through prey distributions, granulometry of the flats influenced shorebird foraging directly by modifying prey availability. Our study highlights the importance of habitat heterogeneity, showing that no single patch type was ideal for the entire shorebird community. Generally, shorebird density and diversity were greatest at lower elevations on flats when they became exposed; these

  7. Wich Parameter of the Carbonate System Influences the Boron Isotopic Composition and the Boron Calcium Ratio in Foraminiferal Tests?

    Science.gov (United States)

    Kaczmarek, K.; Nehrke, G.; Horn, I.; Langer, G.; Misra, S.; Bijma, J.

    2013-12-01

    We performed culture experiments with the benthic symbiont bearing foraminifer Amphistegina lessonii in order to determine which parameter of the marine carbonate system influences the boron isotopic composition (δ11B) and the boron calcium ratio (B/Ca) in the test. A. lessonii grew for two months in treatments of culture media with decoupled pH-carbonate chemistry. We measured δ11B and B/Ca simultaneously on single tests using a recently new developed mass spectrometric technique. Our results show a clear pH dependence on δ11B. The B/Ca in the shell show a positive correlation with aqueous B(OH)4-/HCO3-.

  8. Naturally Ocurring Polyphosphate-accumulating Bacteria in Benthic Biofilms

    Science.gov (United States)

    Locke, N. A.; Saia, S. M.; Walter, M. T.; Carrick, H. J.; Buda, A. R.; Regan, J. M.

    2014-12-01

    Polyphosphate accumulating organisms (PAOs), known to store excess phosphorus (P) as polyphosphate (poly-P), influence P transport in the environment. Enhanced biological phosphorus removal (EBPR) from wastewater has long served as a basis to study bacterial PAOs, yet little research has genetically identified similar organisms in natural settings. Aerobic/anaerobic cycles, used to select for PAOs in EBPR, can result from changing environmental conditions such as night/day cycles for benthic biofilms. Benthic biofilms from eight Pennsylvanian streams were studied for naturally-occurring bacterial PAOs similar to those typically found in EBPR systems. PAOs were confirmed in the benthic biofilms by a characteristic yellow fluorescent emission from DAPI staining. Cells containing yellow fluorescence were separated from the rest of the sample using a flow cytometer, resulting in a physically enriched culture of PAOs from the benthic biofilms. Amplicon-based metagenomic sequencing will reveal the phylogeny of bacteria responsible for poly-P accumulation in these benthic biofilms. Sequencing data will be used to develop fluorescent in-situ hybridization (FISH) probes, and hybridizations will be performed on DAPI-stained cells to confirm poly-P accumulation by targeted phylotypes. Identifying PAOs in natural settings is a critical step towards studying environments that support high concentrations of PAOs, serving as significant factors in the P cycle. PAOs can then be connected to P transport models to help understand and mitigate P pollution in agricultural watersheds.

  9. 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

  10. Quo vadis NW Black Sea benthic ecosystems?

    Science.gov (United States)

    Traian Gomoiu, Marian

    2016-04-01

    The author briefly presents a general review on the evolution trends of benthic ecosystems at the Romanian Black Sea coast, referring to some recent data from the literature. The Black Sea represents a "unicum hydrobiologicum" by some of its basic characteristics, such as: 1. a large semi-enclosed basin with an intense exchange of waters; 2. a sea receiving a large amount of fresh water, especially in its northwestern sector, brought by the Danube, Dnieper and Dniester Rivers; 3. a large meromictic sea - euxinic-azoic below depths of 150 - 200 m; 4. around the sea there is a large filter-holding belt consisting of bivalves (Mytilus galloprovincialis and Modiolula phaseolina); 5. a sea having in its northwestern sector a large area covered by red algae of the genus Phyllophora; 6. a sea undergoing, in the last 50 years, intense environmental pressures (pollution by large rivers and direct discharges of wastewater from urban areas, the development of maritime traffic, overfishing by bottom trawling, coastal facilities and especially by many defense works of the new port); 7. a sea registering in the last decades of the past century many events of eutrophication; 8. a sea enriching its biodiversity by alien species. After the political and socio-economic changes triggered by the events of 1989 and especially after Romania's accession to EU, the state of the northwestern Black Sea coastal ecosystems, has recorded positive changes: • Decrease in environmental pressures; • Decreasing pollutant / fertilizing discharges into the Danube; • Reduction of domestic sewage quantities from coastal settlements; • Improvement in the quality of the wastewater discharged into the sea; • Reduction of active fishing by bottom trawling; • Adopting and implementing a national / international set of guidelines concerning marine environment; • Adopting regulations on the protection of the marine environment against pollution in marine economy: transport / shipping, tourism

  11. Sea Carousel—A benthic, annular flume

    Science.gov (United States)

    Amos, Carl L.; Grant, J.; Daborn, G. R.; Black, K.

    1992-06-01

    A benthic annular flume (Sea Carousel) has been developed and tested to measure in situ the erodibility of cohesive sediments. The flume is equipped with three optical backscatter sensors, a lid rotation switch, and an electromagnetic (EM) flow meter capable of detecting azimuthal and vertical components of flow. Data are logged at rates up to 10·66 Hz. Erodibility is inferred from the rate of change in suspended sediment concentration detected in the annulus. The energy-density/wave number spectrum of azimuthal flow showed peaks in the energy spectrum at paddle rotation wave numbers (k) of 14 and 7 m -1 (macroturbulent time scales) but were not significant. Friction velocity ( U*), measured (1) at 1 Hz using a flush-mounted hot-film sensor, and (2) derived from measured velocity profiles in the inner part of the logarithmic layer gave comparable results for Ū* 0·32 m s -1. Radial velocity gradients were proportional to ( Ū y - 0·32 m s -1). Maximum radial differences in U* were 10% for Ū y = 0·5 ms -1. Suspended sediment mass concentration ( S) in the annulus resulted in a significant decrease (10·5%) in Ū* derived by method (1) over the range 0calibration with changes in S. Subaerial deployments of Sea Carousel caused severe substrate disturbance, water losses, and aeration of the annulus. Submarine deployments produced stable results, though dispersion of turbid flume water took place. Results clearly demonstrated the existence of 'Type I' and 'Type II' erosion documented from laboratory studies.

  12. Assessing effects of water abstraction on fish assemblages in Mediterranean streams

    Science.gov (United States)

    Benejam, Lluis; Angermeier, Paul L.; Munne, Antoni; García-Berthou, Emili

    2010-01-01

    1. Water abstraction strongly affects streams in arid and semiarid ecosystems, particularly where there is a Mediterranean climate. Excessive abstraction reduces the availability of water for human uses downstream and impairs the capacity of streams to support native biota. 2. We investigated the flow regime and related variables in six river basins of the Iberian Peninsula and show that they have been strongly altered, with declining flows (autoregressive models) and groundwater levels during the 20th century. These streams had lower flows and more frequent droughts than predicted by the official hydrological model used in this region. Three of these rivers were sometimes dry, whereas there were predicted by the model to be permanently flowing. Meanwhile, there has been no decrease in annual precipitation. 3. We also investigated the fish assemblage of a stream in one of these river basins (Tordera) for 6 years and show that sites more affected by water abstraction display significant differences in four fish metrics (catch per unit effort, number of benthic species, number of intolerant species and proportional abundance of intolerant individuals) commonly used to assess the biotic condition of streams. 4. We discuss the utility of these metrics in assessing impacts of water abstraction and point out the need for detailed characterisation of the natural flow regime (and hence drought events) prior to the application of biotic indices in streams severely affected by water abstraction. In particular, in cases of artificially dry streams, it is more appropriate for regulatory agencies to assign index scores that reflect biotic degradation than to assign ‘missing’ scores, as is presently customary in assessments of Iberian streams.

  13. 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.

  14. 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.

  15. Immediate response of meio and macrobenthos to disturbance caused by a benthic disturber

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Ansari, Z.A.; Matondkar, S.G.P.; Rodrigues, N.

    The probable impact of nodule mining on benthic biota was studied by creating a benthic disturbance. During the predisturbance study in the Central Indian Basin, box core samples were analyzed for the distribution, composition and abundance...

  16. Benthic foraminifera as proxy for oxygen-depleted conditions off the central west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Mazumder, A.; Henriques, P.J.; Saraswat, R.

    In order to study the response of benthic foraminifera, especially the rectilinear bi- and tri-serial benthic foraminifera (RBF) to oxygen-depleted conditions from the Arabian Sea off central west coast of India, 103 surface sediment samples...

  17. Linkages between reef fish demographics and benthic habitat characteristics in Tutuila, American Samoa

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic habitats play vital roles in the distribution and abundances of marine resources. Understanding how fish populations respond to variability of benthic...

  18. An assemblage of mollusks associated with the high latitude scleractinian coral Alveopora japonica (Eguchi 1968) in Jeju Island, off the south coast of Korea

    Science.gov (United States)

    Noseworthy, Ronald G.; Hong, Hyun-Ki; Keshavmurthy, Shashank; Lee, Hee-Jung; Jeung, Hee-Do; Ju, Se-Jong; Kim, Jong-Bin; Jung, Sukgeun; Choi, Kwang-Sik

    2016-03-01

    Corals reefs and communities support a wide range of flora and fauna. The complete richness and abundance of faunal communities in either coral reefs or communities is not fully understood. This is especially true for high-latitude coral communities. In this work, we carried out an analysis of an Alveopora japonica associated mollusk assemblage, in Jeju Island, Korea. A. japonica is one of the major coral species present in high abundance (88-155 colonies m-2), with a high recruitment rate (7.8 juvenile corals m-2 yr-1) in Jeju Island, and may serve as a habitat for other benthic organisms. In 2012, a total number of 579 A. japonica colonies with sizes ranging between 15.1-346.7 cm2 in the surface area were collected from a 1m× 10m quadrat installed at a depth of 10 m at Keumneung, on the northwest coast of Jeju Island. Numerous benthic invertebrates were found to be associated with A. japonica colonies. Twenty-seven bivalves and gastropods were identified, including a boring mytilid, Lithophaga curta, and an arcid, Barbatia stearnsi. A zonalgeographical examination of the distribution ranges of these mollusks revealed a majority of warmer water species. Our observations also showed that A. japonica may be providing a habitat to grazing gastropod, Turbo cornutus, and encrusting Spondylidae and Chamidae bivalves. A. japonica forms a coral carpet with a distinct assemblage of bivalves. It is thought that the presence of these mollusks species in the coral indicates its use as a nursery for juvenile species, a ready food supply of organic detritus, and a refuge from predators.

  19. 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

  20. Rising from the ashes: Changes in salmonid fish assemblages after 30 months of the Puyehue-Cordon Caulle volcanic eruption.

    Science.gov (United States)

    Lallement, Mailén; Macchi, Patricio J; Vigliano, Pablo; Juarez, Santiago; Rechencq, Magalí; Baker, Matthew; Bouwes, Nicolaas; Crowl, Todd

    2016-01-15

    Events such as volcanic eruptions may act as disturbance agents modifying the landscape spatial diversity and increasing environmental instability. On June 4, 2011 the Puyehue-Cordon Caulle volcanic complex located on Chile (2236 m.a.s.l., 40° 02' 24" S- 70° 14' 26" W) experience a rift zone eruption ejecting during the first day 950 million metric tons into the atmosphere. Due to the westerly winds predominance, ash fell differentially upon 24 million ha of Patagonia Argentinean, been thicker deposits accumulated towards the West. In order to analyze changes on stream fish assemblages we studied seven streams 8, 19 and 30 months after the eruption along the ash deposition gradient, and compare those data to pre eruption ones. Habitat features and structure of the benthic macroinvertebrate food base of fish was studied. After the eruption, substantial environmental changes were observed in association with the large amount of ash fallout. In western sites, habitat loss due to ash accumulation, changes in the riparian zone and morphology of the main channels were observed. Turbidity was the water quality variable which reflected the most changes throughout time, with NTU values decreasing sharply from West to East sites. In west sites, increased Chironomid densities were recorded 8 months after the initial eruption as well as low EPT index values. These relationships were reversed in the less affected streams farther away from the volcano. Fish assemblages were greatly influenced both by habitat and macroinvertebrate changes. The eruption brought about an initial sharp decline in fish densities and the almost total loss of young of the year in the most western streams affecting recruitment. This effect diminished rapidly with distance from the emission center. Thirty months after the eruption, environmental changes are still occurring as a consequence of basin wide ash remobilization and transport. PMID:26473706

  1. The role of the hydrological cycle on the temporal patterns of macroinvertebrate assemblages in an Andean foothill stream in Colombia

    Directory of Open Access Journals (Sweden)

    María I. Ríos-Pulgarín

    2016-03-01

    Full Text Available The seasonal and interannual changes in the structure, composition and functional feeding groups of the macroinvertebrate assemblage of the Guarinó River, a torrential system located in the Colombian Andean foothills, were examined in relation to the physical and chemical environmental changes associated with the hydrological cycle and the El Niño-Niña/Southern Oscillation (ENSO between 2007 and 2010. Benthic samples were collected at three sites in the lower sections of the river. A total of 127 taxa were collected in the study, with the total taxonomic richness per site ranging from 82 to 96 taxa and benthos density averaging 5.41 ind. m-2. The density showed a tendency to decrease in periods of maximum river level and flow, particularly during La Niña phenomena, and to increase in dry periods, especially in the third year (2009-2010 during El Niño phenomena. The presence and abundance of taxa, functional feeding groups and life habits were regulated by environmental parameters associated with hydrological variability, derived of ENSO phenomena, especially flow rate values. The assemblage showed high taxonomic and functional diversity, which is characteristic of ecosystems affected by recurrent hydrological disturbances, exhibiting differentiated responses based on adaptive strategies against the local hydrologic regime that allow fast recovery under conditions like ENSO phenomena. Such responses include composition changes according to adaptations to different hydrological scenarios, the predominance of generalist trophic guilds and taxa with plasticity in their habits and range of environmental tolerance.

  2. Benthic plastic debris in marine and fresh water environments.

    Science.gov (United States)

    Corcoran, Patricia L

    2015-08-01

    This review provides a discussion of the published literature concerning benthic plastic debris in ocean, sea, lake, estuary and river bottoms throughout the world. Although numerous investigations of shoreline, surface and near-surface plastic debris provide important information on plastic types, distribution, accumulation, and degradation, studies of submerged plastic debris have been sporadic in the past and have become more prominent only recently. The distribution of benthic debris is controlled mainly by combinations of urban proximity and its association with fishing-related activities, geomorphology, hydrological conditions, and river input. High density plastics, biofouled products, polymers with mineral fillers or adsorbed minerals, and plastic-metal composites all have the potential to sink. Once deposited on the bottoms of water basins and channels, plastics are shielded from UV light, thus slowing the degradation process significantly. Investigations of the interactions between benthic plastic debris and bottom-dwelling organisms will help shed light on the potential dangers of submerged plastic litter. PMID:26129903

  3. Quantifying tidally driven benthic oxygen exchange across permeable sediments

    DEFF Research Database (Denmark)

    McGinnis, Daniel F.; Sommer, Stefan; Lorke, Andreas;

    2014-01-01

    of permeable sediments and has been identified as increasingly at risk for developing hypoxia. Therefore, we investigate the benthic O-2 exchange across the permeable North Sea sediments using a combination of in situ microprofiles, a benthic chamber, and aquatic eddy correlation. Tidal bottom currents drive....... The high O-2 flux variability results from deeper sediment O-2 penetration depths and increased O-2 storage during high velocities, which is then utilized during low-flow periods. The study reveals that the benthic hydrodynamics, sediment permeability, and pore water redox oscillations are all intimately......Continental shelves are predominately (approximate to 70%) covered with permeable, sandy sediments. While identified as critical sites for intense oxygen, carbon, and nutrient turnover, constituent exchange across permeable sediments remains poorly quantified. The central North Sea largely consists...

  4. A megasplice of globally distributed benthic δ18O records exposes the different astronomical rhythms of the last 35 million years.

    Science.gov (United States)

    De Vleeschouwer, David; Vahlenkamp, Maximilian; Crucifix, Michel; Pälike, Heiko

    2016-04-01

    visualize non-trivial dependencies of climate on the phase and amplitude of astronomical parameters. The megasplice allows for a countless amount of comparisons of the climate's response to astronomical forcing between different time slices. For example, a comparison of the response before and after the Oligocene-Miocene transition shows that it was predominantly the northern hemisphere that drove global climate during the Oligocene, and the southern hemisphere during the Miocene. References Cramer, B. S., Toggweiler, J. R., Wright, J. D., Katz, M. E., and Miller, K. G., 2009, Ocean overturning since the Late Cretaceous: Inferences from a new benthic foraminiferal isotope compilation: Paleoceanography, v. 24, no. 4. Zachos, J., Pagani, M., Sloan, L., Thomas, E., and Billups, K., 2001, Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present: Science, v. 292, no. 5517, p. 686-693. Zachos, J. C., Dickens, G. R., and Zeebe, R. E., 2008, An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics: Nature, v. 451, no. 7176, p. 279-283.

  5. Controlling benthic release of phosphorus in different Baltic Sea scales

    DEFF Research Database (Denmark)

    Pitkänen, Heikki; Bendtsen, Jørgen; Hansen, Jørgen L. S.; Lehtoranta, Jouni; Lännergren, Christer; Ollikainen, Markku; Priha, Maarit; Reinikainen, Marko; Saarijärvi, Erkki; Zandersen, Marianne

    The general aim of the PROPPEN project was to study whether it is possible to counteract near-bottom anoxia and excess benthic nutrient release ("internal loading") in the Baltic Sea by artificial oxygenation in cost-efficient and socio-economically beneficial ways. Two pilot sites were selected...... possibilities to counteract anoxia and benthic release of nutrients in coastal marine conditions in the Baltic Sea. The project undertook monitoring of the pilot tests, modelling of effects at different scales, risk management, cost effectiveness and cost benefit analysis....

  6. Global equatorial sea-surface temperatures over the last 150,000 years: An update from foraminiferal elemental analysis

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.

    , and Prediction (CLIMAP)’ project undertaken in the 1970s and 1980s. The outcome of the CLIMAP project was no or little cooling in the equatorial region during LGM. However, an overall cool- ing of the earth by 3.0 ± 0.6°C during LGM was estima- ted 3...–5 . The occurrence of distinct assemblages of planktic foraminifera in waters of different temperatures was util- ized during the CLIMAP project. However, the reliability of CLIMAP-estimated SSTs was questioned, especially because it interpreted warmer western...

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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].

  12. 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

  13. 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’.

  14. 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.

  15. 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

  16. 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

  17. 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

  18. Long-term benthic infaunal monitoring at a deep-ocean dredged material disposal site off Northern California

    Science.gov (United States)

    Blake, James A.; Maciolek, Nancy J.; Ota, Allan Y.; Williams, Isabelle P.

    2009-09-01

    One hundred and thirty-five benthic infaunal samples were collected from the San Francisco Deep-Ocean Disposal Site (SF-DODS) over a 10-year period from January 1996 to September 2004. Each sample was 0.1 m 2, cut to a depth of 10 cm, and sieved through a 300-μm mesh. A total of 810 species of benthic invertebrates were identified; the majority of taxa (65.4%) new to science. The fauna represents a rich lower slope infaunal assemblage that rivals similarly studied locations in the western North Atlantic. No regional impact or degradation of benthic infauna due to dredged material disposal was detected. All reference stations and stations on the site boundary maintained high species richness and diversity during the monitoring period. Exceptions included an occasional sample with anomalously high numbers of one or two species that reduced the diversity and/or equitability. Within SF-DODS species richness and diversity were often reduced. Stations within the disposal site were recolonized by the same taxa that normally occurred in adjacent reference areas. Initial colonizers of fresh dredged material included spionid and paraonid polychaetes that were typical dominants at the site. At least one polychaete species, Ophelina sp. 1, sometimes colonized dredged materials containing coarse sand. One sample at Station 13, located in the middle of SF-DODS (September 2002), contained 57 species of benthic invertebrates, suggesting that colonization of fresh dredged material is rapid. It seems unlikely that larval dispersal and settlement account for this rapid recolonization; therefore it is postulated that adult organisms from adjacent areas move to the disturbed sites via boundary layer currents. The steep continental slope adjacent to SF-DODS is subject to turbidity flows and the resident fauna are likely pre-adapted to rapidly colonize disturbed sediments. Larval dispersal, especially by spionid polychaetes such as Prionospio delta, may also be important in colonizing

  19. 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.

  20. 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