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Sample records for mediterranean seagrass posidonia

  1. Nitrogen-fixing bacteria in Mediterranean seagrass (Posidonia oceanica) roots

    KAUST Repository

    Garcias Bonet, Neus

    2016-03-09

    Biological nitrogen fixation by diazotrophic bacteria in seagrass rhizosphere and leaf epiphytic community is an important source of nitrogen required for plant growth. However, the presence of endophytic diazotrophs remains unclear in seagrass tissues. Here, we assess the presence, diversity and taxonomy of nitrogen-fixing bacteria within surface-sterilized roots of Posidonia oceanica. Moreover, we analyze the nitrogen isotopic signature of seagrass tissues in order to notice atmospheric nitrogen fixation. We detected nitrogen-fixing bacteria by nifH gene amplification in 13 out of the 78 roots sampled, corresponding to 9 locations out of 26 meadows. We detected two different types of bacterial nifH sequences associated with P. oceanica roots, which were closely related to sequences previously isolated from the rhizosphere of a salt marsh cord grass and a putative anaerobe. Nitrogen content of seagrass tissues showed low isotopic signatures in all the sampled meadows, pointing out the atmospheric origin of the assimilated nitrogen by seagrasses. However, this was not related with the presence of endophytic nitrogen fixers, suggesting the nitrogen fixation occurring in rhizosphere and in the epiphytic community could be an important source of nitrogen for P. oceanica. The low diversity of nitrogen-fixing bacteria reported here suggests species-specific relationships between diazotrophs and P. oceanica, revealing possible symbiotic interactions that could play a major role in nitrogen acquisition by seagrasses in oligotrophic environments where they form lush meadows.

  2. Linking Seed Photosynthesis and Evolution of the Australian and Mediterranean Seagrass Genus Posidonia.

    Directory of Open Access Journals (Sweden)

    David Celdran

    Full Text Available Recent findings have shown that photosynthesis in the skin of the seed of Posidonia oceanica enhances seedling growth. The seagrass genus Posidonia is found only in two distant parts of the world, the Mediterranean Sea and southern Australia. This fact led us to question whether the acquisition of this novel mechanism in the evolution of this seagrass was a pre-adaptation prior to geological isolation of the Mediterranean from Tethys Sea in the Eocene. Photosynthetic activity in seeds of Australian species of Posidonia is still unknown. This study shows oxygen production and respiration rates, and maximum PSII photochemical efficiency (Fv : Fm in seeds of two Australian Posidonia species (P. australis and P. sinuosa, and compares these with previous results for P. oceanica. Results showed relatively high oxygen production and respiratory rates in all three species but with significant differences among them, suggesting the existence of an adaptive mechanism to compensate for the relatively high oxygen demands of the seeds. In all cases maximal photochemical efficiency of photosystem II rates reached similar values. The existence of photosynthetic activity in the seeds of all three species implicates that it was an ability probably acquired from a common ancestor during the Late Eocene, when this adaptive strategy could have helped Posidonia species to survive in nutrient-poor temperate seas. This study sheds new light on some aspects of the evolution of marine plants and represents an important contribution to global knowledge of the paleogeographic patterns of seagrass distribution.

  3. Reduced carbon sequestration in a Mediterranean seagrass (Posidonia oceanica) ecosystem impacted by fish farming

    DEFF Research Database (Denmark)

    Apostolaki, E; Holmer, Marianne; Marbà, N;

    2011-01-01

    We studied the relationship between sediment nutrient enrichment and carbon sequestration, using the ratio of gross primary production to respiration (P/R), in a fish-farming impacted and an unaffected Mediterranean seagrass (Posidonia oceanica) ecosystem in the Aegean Sea, Greece. Carbon (C...... nutrient enrichment. Threshold values are given for C, N and P sedimentation rates and sediment pools, and for N and P concentrations in pore waters, after which P/R ratio in the seagrass meadow decreases below 1, indicating a shift from autotrophy to heterotrophy with sediment nutrient enrichment...

  4. Epiphyte dynamics and carbon metabolism in a nutrient enriched Mediterranean seagrass ( Posidonia oceanica ) ecosystem

    Science.gov (United States)

    Apostolaki, Eugenia T.; Holmer, Marianne; Marbà, Núria; Karakassis, Ioannis

    2011-08-01

    The study aimed at examining the relationship between epiphyte dynamics and carbon metabolism in seagrass ecosystems under nutrient enrichment. Temporal variability of epiphytes and factors controlling their dynamics (i.e. environmental conditions, substratum availability, substratum stability and herbivore pressure) were assessed in a fish farm impacted and an unaffected Mediterranean seagrass ( Posidonia oceanica) meadow in the Aegean Sea (Greece). The factors controlling epiphyte dynamics responded differently to nutrient enrichment and partly interacted, rendering their cumulative effect on epiphyte load difficult to elucidate. Yet epiphytes accumulated on seagrass leaves near to the fish farm throughout the year, contributing 2 times more in above-ground biomass at cages than the control station. Reduction in substratum availability (i.e. decrease in leaf biomass) and increase in herbivore pressure affected epiphyte load, albeit their effects were not strong enough to counterbalance the effect of nutrient input from fish farm effluents. Moderate yet continuous nutrient input possibly stimulated epiphyte growth in excess of herbivory, shifting the control of epiphytes from top-down to bottom-up. Epiphyte accumulation affected carbon metabolism in the seagrass ecosystem by contributing to enhanced dissolved organic carbon (DOC) release, but seagrass loss was so acute that increased epiphyte cover could not counterbalance the decrease in community carbon production which was mainly driven by seagrass decline.

  5. Influence of microhabitat on seedling survival and growth of the mediterranean seagrass posidonia oceanica (l.) Delile

    Science.gov (United States)

    Alagna, Adriana; Fernández, Tomás Vega; Terlizzi, Antonio; Badalamenti, Fabio

    2013-03-01

    Early life history phases are crucial stages limiting species distribution and abundance, thus influencing assemblage composition in marine benthic environments. In seagrass systems the period between seed germination and establishment is one of the most vulnerable phases for plant development. This study analyzes the influence of microhabitat structure, in terms of substrate nature and algal canopy, on the persistence and growth over two years of seedlings of Posidonia oceanica, the dominant Mediterranean seagrass. Long time persistence of seedlings only occurred on microhabitats providing vegetated rocky substrates, with a maximum value of 81% on rock covered by Cystoseira spp. No seedling was found on unvegetated sand and gravel after the first year. Seedling growth resulted increased on rock covered by Halopteris spp. and Dilophus spp. than on rock covered by Cystoseira spp. Results suggest that high canopy onto a stable substrate enhances seedling persistence, probably because these allow the best anchorage by roots while hampering water flow. In contrast, turf algal cover promotes better seedling growth, possibly through higher light irradiance and nutrient availability. Our findings support the view that the understanding of the factors controlling early life processes is a necessary prerequisite for the comprehension of seagrass species distribution patterns, colonization and recovery potentials, which, in turn, can guide sound strategies for seagrass management and restoration.

  6. Palaeoclimatic conditions in the Mediterranean explain genetic diversity of Posidonia oceanica seagrass meadows

    KAUST Repository

    Chefaoui, Rosa M.

    2017-05-26

    Past environmental conditions in the Mediterranean Sea have been proposed as main drivers of the current patterns of distribution of genetic structure of the seagrass Posidonia oceanica, the foundation species of one of the most important ecosystems in the Mediterranean Sea. Yet, the location of cold climate refugia (persistence regions) for this species during the Last Glacial Maximum (LGM) is not clear, precluding the understanding of its biogeographical history. We used Ecological Niche Modelling together with existing phylogeographic data to locate Pleistocene refugia in the Mediterranean Sea and to develop a hypothetical past biogeographical distribution able to explain the genetic diversity presently found in P. oceanica meadows. To do that, we used an ensemble approach of six predictive algorithms and two Ocean General Circulation Models. The minimum SST in winter and the maximum SST in summer allowed us to hindcast the species range during the LGM. We found separate glacial refugia in each Mediterranean basin and in the Central region. Altogether, the results suggest that the Central region of the Mediterranean Sea was the most relevant cold climate refugium, supporting the hypothesis that long-term persistence there allowed the region to develop and retain its presently high proportion of the global genetic diversity of P. oceanica.

  7. Anatomically and morphologically unique dark septate endophytic association in the roots of the Mediterranean endemic seagrass Posidonia oceanica.

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    Vohník, Martin; Borovec, Ondřej; Župan, Ivan; Vondrášek, David; Petrtýl, Miloslav; Sudová, Radka

    2015-11-01

    Roots of terrestrial plants host a wide spectrum of soil fungi that form various parasitic, neutral and mutualistic associations. A similar trend is evident in freshwater aquatic plants and plants inhabiting salt marshes or mangroves. Marine vascular plants (seagrasses), by contrast, seem to lack specific root-fungus symbioses. We examined roots of two Mediterranean seagrasses, Posidonia oceanica and Cymodocea nodosa, in the northwestern Mediterranean Sea for fungal colonization using light and scanning and transmission electron microscopy. We found that P. oceanica, but not C. nodosa, is regularly associated with melanized septate hyphae in a manner resembling colonization by the ubiquitous dark septate endophytes (DSE) in roots of most terrestrial plants. P. oceanica roots were found to be colonized by sparse dematiaceous running hyphae as well as dense parenchymatous nets/hyphal sheaths on the root surface, intracellular melanized microsclerotia and occasionally also intra- and intercellular hyphae. The colonization was most prominent in the thick-walled hypodermis of the thinnest healthy looking roots, and the mycobiont seemed to colonize both living and dead host cells. Dark septate hyphae infrequently occurred also inside rhizodermal cells, but never colonized vascular tissues. The biological significance of this overlooked marine symbiosis remains unknown, but its morphology, extent, distribution across the NW Mediterranean Sea and absence in C. nodosa indicate an intriguing relationship between the dominant Mediterranean seagrass and its dark septate root mycobionts.

  8. Remote influence of off-shore fish farm waste on Mediterranean seagrass (Posidonia oceanica) meadows.

    Science.gov (United States)

    Ruiz, J M; Marco-Méndez, C; Sánchez-Lizaso, J L

    2010-04-01

    The aim of this study was estimating the remote influence of waste dispersed from a large off-shore fish farm complex (6197 ton year(-1)) on the near-shore Posidonia oceanica meadow (26-27 m deep) located at a distance of 3 km. Measurements of isotopic nitrogen content in epiphytes and seagrass leaf tissues, epiphyte biomass, shoot size, herbivory pressure, shoot density and seagrass meadow cover, performed in this meadow (FA area) were compared with those obtained in an undisturbed control meadow (CA area) to evaluate: (1) the remote influence of waste and (2) the impact of such influence on seagrass condition. In addition, delta(15)N measurements in particulate organic matter of natural and anthropogenic origin were used in a single-isotope mixing model to elucidate the relative contributions of these sources to the isotopic N signal measured in epiphytes and leaf tissues. Total tissue N content was similar between meadow areas, but delta(15)N signatures were significantly higher in the FA area than in the CA area both in epiphytes and seagrass leaf tissues. Results from the mixing model, together with available information on local currents and previous studies, support the conclusion that the dispersion of farm wastes over large areas (spanning kilometres) are responsible for the elevated delta(15)N signatures found in the FA meadow area. Despite this, no changes in meadow structure were detected and only some changes at the level of seagrass community (epiphytes abundances and herbivores activity) could be interpreted at the light of nutrient-induced effects in the FA area. Results from this study indicate that concentrating aquaculture facilities in off-shore areas is a strategy not totally exempt of environmental risk on near-shore sensitive habitats such as seagrass meadows.

  9. Communities of Cultivable Root Mycobionts of the Seagrass Posidonia oceanica in the Northwest Mediterranean Sea Are Dominated by a Hitherto Undescribed Pleosporalean Dark Septate Endophyte.

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    Vohník, Martin; Borovec, Ondřej; Kolařík, Miroslav

    2016-02-01

    Seagrasses, a small group of submerged marine macrophytes, were reported to lack mycorrhizae, i.e., the root-fungus symbioses most terrestrial plants use for nutrient uptake. On the other hand, several authors detected fungal endophytes in seagrass leaves, shoots, rhizomes, and roots, and an anatomically and morphologically unique dark septate endophytic (DSE) association has been recently described in the roots of the Mediterranean seagrass Posidonia oceanica. Nevertheless, the global diversity of seagrass mycobionts is not well understood, and it remains unclear what fungus forms the DSE association in P. oceanica roots. We isolated and determined P. oceanica root mycobionts from 11 localities in the northwest Mediterranean Sea with documented presence of the DSE association and compared our results with recent literature. The mycobiont communities were low in diversity (only three species), were dominated by a single yet unreported marine fungal species (ca. 90 % of the total 177 isolates), and lacked common terrestrial and freshwater root mycobionts. Our phylogenetic analysis suggests that the dominating species represents a new monotypic lineage within the recently described Aigialaceae family (Pleosporales, Ascomycota), probably representing a new genus. Most of its examined colonies developed from intracellular microsclerotia occupying host hypodermis and resembling microsclerotia of terrestrial DSE fungi. Biological significance of this hitherto overlooked seagrass root mycobiont remains obscure, but its presence across the NW Mediterranean Sea and apparent root intracellular lifestyle indicate an intriguing symbiotic relationship with the dominant Mediterranean seagrass. Our microscopic observations suggest that it may form the DSE association recently described in P. oceanica roots.

  10. Evidences of adaptive traits to rocky substrates undermine paradigm of habitat preference of the Mediterranean seagrass Posidonia oceanica

    Science.gov (United States)

    Badalamenti, Fabio; Alagna, Adriana; Fici, Silvio

    2015-03-01

    Posidonia oceanica meadows are acknowledged as one of the most valuable ecosystems of the Mediterranean Sea. P. oceanica has been historically described as a species typically growing on mobile substrates whose development requires precursor communities. Here we document for the first time the extensive presence of sticky hairs covering P. oceanica seedling roots. Adhesive root hairs allow the seedlings to firmly anchor to rocky substrates with anchorage strength values up to 5.23 N, regardless of the presence of algal cover and to colonise bare rock without the need for precursor assemblages to facilitate settlement. Adhesive root hairs are a morphological trait common on plants living on rocks in high-energy habitats, such as the riverweed Podostemaceae and the seagrass Phyllospadix scouleri. The presence of adhesive root hairs in P. oceanica juveniles suggests a preference of this species for hard substrates. Such an adaptation leads to hypothesize a new microsite driven bottleneck in P. oceanica seedling survival linked to substrate features. The mechanism described can favour plant establishment on rocky substrates, in contrast with traditional paradigms. This feature may have strongly influenced P. oceanica pattern of colonisation through sexual propagules in both the past and present.

  11. Mapping Mediterranean seagrasses with Sentinel-2 imagery.

    Science.gov (United States)

    Traganos, Dimosthenis; Reinartz, Peter

    2017-07-01

    Mediterranean seagrasses have been hailed for their numerous ecosystem services, yet they are undergoing a decline in their coverage. The major complication with resolving this tendency is the sparsity of data on their overall distribution. This study addresses the suitability of the recently launched Sentinel-2 satellite for mapping the distribution of Mediterranean seagrass meadows. A comprehensive methodology is presented which applies atmospheric and analytical water column corrections and compares the performance of three different supervised classifiers. Remote sensing of the Thermaikos Gulf, northwestern Aegean Sea (Greece, eastern Mediterranean Sea) reveals that the utilization of Support Vector Machines on water column corrected reflectances yields best accuracies. Two Mediterranean seagrasses, Posidonia oceanica and Cymodocea nodosa, cover a total submerged area of 1.48km(2) between depths of 1.4-16.5m. With its 10-m spatial resolution and 5-day revisit frequency, Sentinel-2 imagery can mitigate the Mediterranean seagrass distribution data gap and allow better management and conservation in the future in a retrospective, time- and cost-effective fashion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. A comparison of the impact of 'seagrass-friendly' boat mooring systems on Posidonia australis.

    Science.gov (United States)

    Demers, Marie-Claire A; Davis, Andrew R; Knott, Nathan A

    2013-02-01

    Permanent boat moorings have contributed to the decline of seagrasses worldwide, prompting the development of 'seagrass-friendly' moorings. We contrasted seagrass cover and density (predominantly Posidonia australis) in the vicinity of three mooring types and nearby reference areas lacking moorings in Jervis Bay, Australia. We examined two types of 'seagrass-friendly' mooring and a conventional 'swing' mooring. 'Swing' moorings produced significant seagrass scour, denuding patches of ~9 m radius. Seagrass-friendly 'cyclone' moorings produced extensive denuded patches (average radius of ~18 m). Seagrass-friendly 'screw' moorings, conversely, had similar seagrass cover to nearby reference areas. Our findings reinforce previous work highlighting the negative effects of 'swing' and 'cyclone' moorings. In contrast, the previously unstudied 'screw' moorings were highly effective. We conclude that regular maintenance of moorings and the monitoring of surrounding seagrass are required to ensure that 'seagrass-friendly' moorings are operating effectively. This is important, as following damage Posidonia will take many decades to recover.

  13. Location and associated carbon storage of erosional escarpments of seagrass Posidonia mats

    Directory of Open Access Journals (Sweden)

    Oscar eSerrano

    2016-03-01

    Full Text Available Seagrasses of the genus Posidonia can form an irregular seascape due to erosional processes exposing thick walls of organic matter-rich soils. However, little is known about the location and characteristics of these particular formations. Here we provide comprehensive estimates of organic carbon (Corg storage in P. oceanica and P. australis meadows, while providing insight into their location and mechanisms of formation, and highlighting future research directions. Erosional reef escarpments are restricted to shallow highly productive P. oceanica meadows from the Mediterranean Sea and P. australis meadows from the Indian Ocean, and sustain the existence of Corg-rich deposits in surrounding meadows. The thickness of the mat escarpments can reach up to 3 m and their length can vary from few to hundreds meters. Mechanisms of formation appear to differ among sites, from naturally-induced escarpments by wave action and/or tidal flow to human-induced escarpments by dredging activities. The inter-twined remains of seagrass shoots within the sediment matrix consolidate the sandy substrate and hold the exposed Posidonia mat escarpments together, maintaining a semi-rigid structure. This phenomenon is unusual but of exceptional importance in marine biogeochemical cycles, revealing the largest Corg sinks among seagrasses worldwide (ranging from 15-176 kg Corg m-2 in 2 m-thick mats accumulated at 2-249 g Corg m-2 yr-1 over 300 to 3000 yr.

  14. Aeolian transport of seagrass (Posidonia oceanica) beach-cast to terrestrial systems

    Science.gov (United States)

    Jiménez, Maria A.; Beltran, Rafel; Traveset, Anna; Calleja, Maria Ll; Delgado-Huertas, Antonio; Marbà, Núria

    2017-09-01

    The annual export of the Mediterranean seagrass (Posidonia oceanica) litter to adjacent beaches and coastal dunes was quantified by examining the fortnight evolution of seagrass beach-cast volume on two beaches in the NW Mediterranean (Son Real and Es Trenc, Mallorca Island, Spain) for two years and analyzing the wind speed and direction obtained from the closest Meteorological Spanish Agency surface weather stations. The decomposition stage of the deposits was examined by analyzing the total hydrolysable amino acids, its percentage distribution and derived degradation indexes. Prevalent winds exceeding 6 m s-1, the coastline morphology and type of terrestrial vegetation determine the annual dynamics of the seagrass beach-cast. In the most protected beach (Son Real) the seagrass beach-cast remained nearly stationary during the two studied years while it exhibited wide annual fluctuations in the less protected one (Es Trenc). The amounts of P. oceanica wrack washed on Son Real and Es Trenc beaches, respectively, were estimated at 309 kg DW m coastline-1 yr-1 and 1359 kg DW m coastline-1 yr-1. They supplied between 20 kg CaCO3 m coastline-1 yr-1 and 47 kg CaCO3 m coastline-1 yr-1. Between 54% (Son Real) and 70% (Es Trenc) of seagrass beach-cast, respectively accounting for 1.5 kg N m coastline-1 yr-1 and 8.6 kg N m coastline-1 yr-1, were annually exported from the beaches to adjacent dune systems. Our results reveal that Mediterranean seagrass meadows might be an important source of materials, including sand and nutrients, for adjacent terrestrial systems, able to support their functioning.

  15. Aeolian transport of seagrass ( Posidonia oceanica ) beach-cast to terrestrial systems

    KAUST Repository

    Jiménez, Maria A.

    2017-06-29

    The annual export of the Mediterranean seagrass (Posidonia oceanica) litter to adjacent beaches and coastal dunes was quantified by examining the fortnight evolution of seagrass beach-cast volume on two beaches in the NW Mediterranean (Son Real and Es Trenc, Mallorca Island, Spain) for two years and analyzing the wind speed and direction obtained from the closest Meteorological Spanish Agency surface weather stations. The decomposition stage of the deposits was examined by analyzing the total hydrolysable amino acids, its percentage distribution and derived degradation indexes. Prevalent winds exceeding 6 m s−1, the coastline morphology and type of terrestrial vegetation determine the annual dynamics of the seagrass beach-cast. In the most protected beach (Son Real) the seagrass beach-cast remained nearly stationary during the two studied years while it exhibited wide annual fluctuations in the less protected one (Es Trenc). The amounts of P. oceanica wrack washed on Son Real and Es Trenc beaches, respectively, were estimated at 309 kg DW m coastline−1 yr−1 and 1359 kg DW m coastline−1 yr−1. They supplied between 20 kg CaCO3 m coastline−1 yr−1 and 47 kg CaCO3 m coastline−1 yr−1. Between 54% (Son Real) and 70% (Es Trenc) of seagrass beach-cast, respectively accounting for 1.5 kg N m coastline−1 yr−1 and 8.6 kg N m coastline−1 yr−1, were annually exported from the beaches to adjacent dune systems. Our results reveal that Mediterranean seagrass meadows might be an important source of materials, including sand and nutrients, for adjacent terrestrial systems, able to support their functioning.

  16. Sedimentary iron inputs stimulate seagrass ( Posidonia oceanica) population growth in carbonate sediments

    Science.gov (United States)

    Marbà, Núria; Duarte, Carlos M.; Holmer, Marianne; Calleja, Maria Ll.; Álvarez, Elvira; Díaz-Almela, Elena; Garcias-Bonet, Neus

    2008-02-01

    The relationship between sedimentary Fe inputs and net seagrass population growth across a range of Posidonia oceanica meadows growing in carbonate Mediterranean sediments (Balearic Islands, Spain; SE Iberian Peninsula, Spain; Limassol, Cyprus; Sounion, Greece) was examined using comparative analysis. Sedimentary Fe inputs were measured using benthic sediment traps and the net population growth of P. oceanica meadows was assessed using direct census of tagged plants. The meadows examined ranged from meadows undergoing a severe decline to expanding meadows (specific net population growth, from -0.14 yr -1 to 0.05 yr -1). Similarly, Fe inputs to the meadows ranged almost an order of magnitude across meadows (8.6-69.1 mg Fe m -2 d -1). There was a significant, positive relationship between sedimentary iron inputs and seagrass net population growth, accounting for 36% of the variability in population growth across meadows. The relationship obtained suggested that seagrass meadows receiving Fe inputs below 43 mg Fe m -2 d -1 are vulnerable and in risk of decline, confirming the pivotal role of Fe in the control of growth and the stability of seagrass meadows in carbonate sediments.

  17. The value of the seagrass Posidonia oceanica: a natural capital assessment.

    Science.gov (United States)

    Vassallo, Paolo; Paoli, Chiara; Rovere, Alessio; Montefalcone, Monica; Morri, Carla; Bianchi, Carlo Nike

    2013-10-15

    Making nature's value visible to humans is a key issue for the XXI century and it is crucial to identify and measure natural capital to incorporate benefits or costs of changes in ecosystem services into policy. Emergy analysis, a method able to analyze the overall functioning of a system, was applied to reckon the value of main ecosystem services provided by Posidonia oceanica, a fragile and precious Mediterranean seagrass ecosystem. Estimates, based on calculation of resources employed by nature, resulted in a value of 172 € m(-2)a(-1). Sediment retained by meadow is most relevant input, composing almost the whole P. oceanica value. Remarks about economic losses arising from meadow regression have been made through a time-comparison of meadow maps. Suggested procedure represents an operative tool to provide a synthetic monetary measure of ecosystem services to be employed when comparing natural capital to human and financial capitals in a substitutability perspective.

  18. Impact of the brine from a desalination plant on a shallow seagrass ( Posidonia oceanica) meadow

    Science.gov (United States)

    Gacia, Esperança; Invers, Olga; Manzanera, Marta; Ballesteros, Enric; Romero, Javier

    2007-05-01

    Although seawater desalination has increased significantly over recent decades, little attention has been paid to the impact of the main by-product (hypersaline water: brine) on ecosystems. In the Mediterranean, potentially the most affected ecosystems are meadows of the endemic seagrass Posidonia oceanica. We studied the effect of brine on a shallow P. oceanica meadow exposed to reverse osmosis brine discharge for more than 6 years. P. oceanica proved to be very sensitive to both eutrophication and high salinities derived from the brine discharge. Affected plants showed high epiphyte load and nitrogen content in the leaves, high frequencies of necrosis marks, low total non-structural carbohydrates and low glutamine synthetase activity, compared to control plants. However, there was no indication of extensive decline of the affected meadow. This is probably due to its very shallow situation, which results in high incident radiation as well as fast dilution and dispersion of the brine plume.

  19. The role of the seagrass Posidonia oceanica in the cycling of trace elements

    Science.gov (United States)

    Sanz-Lázaro, C.; Malea, P.; Apostolaki, E. T.; Kalantzi, I.; Marín, A.; Karakassis, I.

    2012-07-01

    The aim of this study was to investigate the role of the seagrass Posidonia oceanica on the cycling of a wide set of trace elements (Ag, As, Ba, Bi, Cd, Co, Cr, Cs, Cu, Fe, Ga, Li, Mn, Ni, Pb, Rb, Sr, Tl, V and Zn). We measured the concentration of these trace elements in different compartments of P. oceanica (leaves, rhizomes, roots and epiphytes) in a non-polluted seagrass meadow representative of the Mediterranean and calculated the annual budget from a mass balance. We provide novel data on accumulation dynamics of many trace elements in P. oceanica compartments and demonstrate that trace element accumulation patterns are mainly determined by plant compartment rather than by temporal variability. Epiphytes were the compartment, which showed the greatest concentrations for most trace elements. Thus, they constitute a key compartment when estimating trace element transfer to higher trophic levels by P. oceanica. Trace element translocation in P. oceanica seemed to be low and acropetal in most cases. Zn, Cd, Sr and Rb were the trace elements that showed the highest release rate through decomposition of plant detritus, while Cs, Tl and Bi showed the lowest. P. oceanica acts as a sink of potentially toxic trace elements (Ni, Cr, As and Ag), which can be sequestered, decreasing their bioavailability. P. oceanica may have a relevant role in the cycling of trace elements in the Mediterranean.

  20. Recruitment and Patch Establishment by Seed in the Seagrass Posidonia oceanica: Importance and Conservation Implications.

    Science.gov (United States)

    Balestri, Elena; Vallerini, Flavia; Lardicci, Claudio

    2017-01-01

    Seagrasses are declining globally, and deeper understanding is needed on the recruitment potential and distribution of new populations for many threatened species to support conservation planning in the face of climate change. Recruitment of Posidonia oceanica, a threatened seagrass endemic to the Mediterranean, has long been considered rare due to infrequent flowering, but mounting evidence demonstrates that the species is responding to a changing climate through greater reproductive effort. Due to the fragmentary information on recruit occurrence and distribution, little is known about reproductive success in the species and its contribution to persistence. We assembled P. oceanica recruitment data from published and unpublished sources, including our own, to examine the frequency and extent of recruitment events (establishment of seedlings in a site), seedling growth potential and habitat characteristics at recruitment sites. Results show that at least one recruitment event has occurred about every 3 years, and 18 localities were colonized at least one time since the first seedling record in 1986. Notably, consistently high seedling inputs were observed in four localities of the Western Mediterranean. Seedlings established mainly on unoccupied substrate areas along the coasts of islands, in sheltered sites and at shallower depths (recruitment is rare and usually unsuccessful for P. oceanica, and highlight the potential importance of recruitment for the long-term persistence and adaptation of the species to sea level rise predicted in the next century in the Mediterranean. Unfortunately, management actions have mainly focused on established meadows, ignoring the presence of recruits in outside areas. Therefore, it will be useful to identify and consider regeneration sites in designing future management strategies to improve seagrass conservation effectiveness.

  1. Is Posidonia oceanica regression a general feature in the Mediterranean Sea?

    Directory of Open Access Journals (Sweden)

    M. BONACORSI

    2013-03-01

    Full Text Available Over the last few years, a widespread regression of Posidonia oceanica meadows has been noticed in the Mediterranean Sea. However, the magnitude of this decline is still debated. The objectives of this study are (i to assess the spatio-temporal evolution of Posidonia oceanica around Cap Corse (Corsica over time comparing available ancient maps (from 1960 with a new (2011 detailed map realized combining different techniques (aerial photographs, SSS, ROV, scuba diving; (ii evaluate the reliability of ancient maps; (iii discuss observed regression of the meadows in relation to human pressure along the 110 km of coast. Thus, the comparison with previous data shows that, apart from sites clearly identified with the actual evolution, there is a relative stability of the surfaces occupied by the seagrass Posidonia oceanica. The recorded differences seem more related to changes in mapping techniques. These results confirm that in areas characterized by a moderate anthropogenic impact, the Posidonia oceanica meadow has no significant regression and that the changes due to the evolution of mapping techniques are not negligible. However, others facts should be taken into account before extrapolating to the Mediterranean Sea (e.g. actually mapped surfaces and assessing the amplitude of the actual regression.

  2. Is Posidonia oceanica regression a general feature in the Mediterranean Sea?

    Directory of Open Access Journals (Sweden)

    M. BONACORSI

    2013-04-01

    Full Text Available Over the last few years, a widespread regression of Posidonia oceanica meadows has been noticed in the Mediterranean Sea. However, the magnitude of this decline is still debated. The objectives of this study are (i to assess the spatio-temporal evolution of Posidonia oceanica around Cap Corse (Corsica over time comparing available ancient maps (from 1960 with a new (2011 detailed map realized combining different techniques (aerial photographs, SSS, ROV, scuba diving; (ii evaluate the reliability of ancient maps; (iii discuss observed regression of the meadows in relation to human pressure along the 110 km of coast. Thus, the comparison with previous data shows that, apart from sites clearly identified with the actual evolution, there is a relative stability of the surfaces occupied by the seagrass Posidonia oceanica. The recorded differences seem more related to changes in mapping techniques. These results confirm that in areas characterized by a moderate anthropogenic impact, the Posidonia oceanica meadow has no significant regression and that the changes due to the evolution of mapping techniques are not negligible. However, others facts should be taken into account before extrapolating to the Mediterranean Sea (e.g. actually mapped surfaces and assessing the amplitude of the actual regression.

  3. Seagrass (Posidonia oceanica) seedlings in a high-CO2 world: from physiology to herbivory

    KAUST Repository

    Hernán, Gema

    2016-12-01

    Under future increased CO2 concentrations, seagrasses are predicted to perform better as a result of increased photosynthesis, but the effects in carbon balance and growth are unclear and remain unexplored for early life stages such as seedlings, which allow plant dispersal and provide the potential for adaptation under changing environmental conditions. Furthermore, the outcome of the concomitant biochemical changes in plant-herbivore interactions has been poorly studied, yet may have important implications in plant communities. In this study we determined the effects of experimental exposure to current and future predicted CO2 concentrations on the physiology, size and defense strategies against herbivory in the earliest life stage of the Mediterranean seagrass Posidonia oceanica. The photosynthetic performance of seedlings, assessed by fluorescence, improved under increased pCO2 conditions after 60 days, although these differences disappeared after 90 days. Furthermore, these plants exhibited bigger seeds and higher carbon storage in belowground tissues, having thus more resources to tolerate and recover from stressors. Of the several herbivory resistance traits measured, plants under high pCO2 conditions had a lower leaf N content but higher sucrose. These seedlings were preferred by herbivorous sea urchins in feeding trials, which could potentially counteract some of the positive effects observed.

  4. Seagrass (Posidonia oceanica) seedlings in a high-CO2 world: from physiology to herbivory

    Science.gov (United States)

    Hernán, Gema; Ramajo, Laura; Basso, Lorena; Delgado, Antonio; Terrados, Jorge; Duarte, Carlos M.; Tomas, Fiona

    2016-01-01

    Under future increased CO2 concentrations, seagrasses are predicted to perform better as a result of increased photosynthesis, but the effects in carbon balance and growth are unclear and remain unexplored for early life stages such as seedlings, which allow plant dispersal and provide the potential for adaptation under changing environmental conditions. Furthermore, the outcome of the concomitant biochemical changes in plant-herbivore interactions has been poorly studied, yet may have important implications in plant communities. In this study we determined the effects of experimental exposure to current and future predicted CO2 concentrations on the physiology, size and defense strategies against herbivory in the earliest life stage of the Mediterranean seagrass Posidonia oceanica. The photosynthetic performance of seedlings, assessed by fluorescence, improved under increased pCO2 conditions after 60 days, although these differences disappeared after 90 days. Furthermore, these plants exhibited bigger seeds and higher carbon storage in belowground tissues, having thus more resources to tolerate and recover from stressors. Of the several herbivory resistance traits measured, plants under high pCO2 conditions had a lower leaf N content but higher sucrose. These seedlings were preferred by herbivorous sea urchins in feeding trials, which could potentially counteract some of the positive effects observed. PMID:27905514

  5. Temporal trends of littoral fishes at deep Posidonia oceanica seagrass meadows in a temperate coastal zone

    Science.gov (United States)

    Deudero, Salud; Morey, Gabriel; Frau, Antoni; Moranta, Joan; Moreno, Isabel

    Seasonal abundance and biomass of littoral fish at Posidonia oceanica seagrass meadows were characterized throughout an annual cycle in Mediterranean waters. Bimonthly beam trawl hauls were performed between 18 and 38 m depth at 4 sites sampling from 2 locations. Approximately 8230 littoral fish were collected belonging to 25 families and 51 species with Labridae and Sparidae families being predominant in terms of abundance. Mean fish abundance was 92 ± 7.5 individuals · 1000 m - 2 peaking in March, April and September and total abundance showed significant statistical differences between May and October. Densities of Diplodus annularis, Gobius sp., Mullus surmuletus, Parablennius tentacularis, Sarpa salpa, Sciaena umbra, Scorpaena porcus, Serranus cabrilla, Symphodus ocellatus, Symphodus rostratus, Symphodus tinca and Synodus saurus differed significantly between seasons. Total community biomass varied significantly along the year with maximum values observed in July (1500 g · 1000 m - 2 ) and minimum biomass recorded in October. The number of species ranged between 5 in January and 21 in July while the total number of individuals was 293 in July and 21 in September, and Margalef diversity index differed between 4.11 in July and 1.3 in January. Biomass peaked in summer linked mainly to the increase of S. porcus, Serranus scriba and some Symphodus species. Diversity was maximal in July and the larger mean size for most of the fish species was achieved from May to July corresponding to the recruitment peaks of some of the fish species. The SIMPER analysis showed that there are seasonal differences in the trophic roles of the fish communities at seagrass meadows. The temporal patterns observed highlight the multifunctional role of deep seagrass meadows during the summer months when all the measured parameters are maximal. Those observations point out the need for conservation measures to be intensified in the warm season.

  6. A Comparison of Abundance and Diversity of Epiphytic Microalgal Assemblages on the Leaves of the Seagrasses Posidonia oceanica (L.) and Cymodocea nodosa (Ucria) Asch in Eastern Tunisia

    National Research Council Canada - National Science Library

    Lotfi Mabrouk; Mounir Ben Brahim; Asma Hamza; Mabrouka Mahfoudhi; Med Najmeddine Bradai

    2014-01-01

      We studied spatial patterns in assemblages of epiphytic microalgae on the leaves of two seagrass species with different morphologies and longevity, Cymodocea nodosa and Posidonia oceanica, which...

  7. Epiphyte presence and seagrass species identity influence rates of herbivory in Mediterranean seagrass meadows

    Science.gov (United States)

    Marco-Méndez, Candela; Ferrero-Vicente, Luis Miguel; Prado, Patricia; Heck, Kenneth L.; Cebrián, Just; Sánchez-Lizaso, Jose Luis

    2015-03-01

    Herbivory on Mediterranean seagrass species is generally low compared to consumption of some other temperate and tropical species of seagrasses. In this study we: (1) investigate the feeding preference of the two dominant Mediterranean seagrass herbivores, the sea urchin Paracentrotus lividus and the fish Sarpa salpa, on Posidonia oceanica and Cymodocea nodosa and (2) elucidate the role of epiphytes in herbivore choices. We assessed consumption rates by tethering seagrass shoots, and preferences by food choice experiments with the following paired combinations: 1) Epiphytized leaves of both C. nodosa vs. P. oceanica (CE vs PE); 2) Non-epiphytized leaves of C. nodosa vs. P. oceanica (CNE vs. PNE); 3) Epiphytized vs non-epiphytized leaves of C. nodosa (CE vs. CNE) and 4) Epiphytized vs non-epiphytized leaves of P. oceanica (PE vs PNE). We found that preference for C. nodosa was weak for S. salpa, but strong for P. lividus, the species responsible for most consumption at our study. Overall both herbivores showed preference for epiphytized leaves. The higher nutritional quality of C. nodosa leaves and epiphytes together with the high coverage and diversity of the epiphyte community found on its leaves help explain the higher levels of herbivory recorded on epiphyted leaves of C. nodosa. Other factors such as seagrass accessibility, herbivore mobility and size, and behavioral responses to predation risks, may also affect the intensity of seagrass herbivory, and studies addressing the interactions with these factors are needed to improve our understanding of the nature, extent and implications of herbivory in coastal ecosystems.

  8. Lulwoana sp., a dark septate endophyte in roots of Posidonia oceanica (L.) Delile seagrass.

    Science.gov (United States)

    Torta, L; Lo Piccolo, S; Piazza, G; Burruano, S; Colombo, P; Ottonello, D; Perrone, R; Di Maida, G; Pirrotta, M; Tomasello, A; Calvo, S

    2015-03-01

    Posidonia oceanica is the most common, widespread and important monocotyledon seagrass in the Mediterranean Basin, and hosts a large biodiversity of species, including microorganisms with key roles in the marine environment. In this study, we ascertain the presence of a fungal endophyte in the roots of P. oceanica growing on different substrata (rock, sand and matte) in two Sicilian marine meadows. Staining techniques on root fragments and sections, in combination with microscope observations, were used to visualise the fungal presence and determine the percentage of fungal colonisation (FC) in this tissue. In root fragments, statistical analysis of the FC showed a higher mean in roots anchored on rock than on matte and sand. In root sections, an inter- and intracellular septate mycelium, producing intracellular microsclerotia, was detected from the rhizodermis to the vascular cylinder. Using isolation techniques, we obtained, from both sampling sites, sterile, slow-growing fungal colonies, dark in colour, with septate mycelium, belonging to the dark septate endophytes (DSEs). DNA sequencing of the internal transcribed spacer (ITS) region identified these colonies as Lulwoana sp. To our knowledge, this is the first report of Lulwoana sp. as DSE in roots of P. oceanica. Moreover, the highest fungal colonisation, detected in P. oceanica roots growing on rock, suggests that the presence of the DSE may help the host in several ways, particularly in capturing mineral nutrients through lytic activity.

  9. The seagrass Posidonia oceanica: Ecosystem services identification and economic evaluation of goods and benefits.

    Science.gov (United States)

    Campagne, Carole Sylvie; Salles, Jean-Michel; Boissery, Pierre; Deter, Julie

    2015-08-15

    Posidonia oceanica is a marine angiosperm endemic from the Mediterranean. Despite their protection, its meadows are regressing. The economic valuation of ecosystem services (ES) assesses the contribution of ecosystems to human well-being and may provide local policy makers help in territorial development. To estimate the economic value of P. oceanica seagrass and the meadows that it forms to better account its presence in coastal development, identification and assessment of ES provided are first performed. Then goods and benefits (GB) and their economical values are estimated. In total, 25ES are identified and 7GB are economically evaluated. The economic value of GB provided by P. oceanica ranges between 25.3 million and 45.9 million€/year which means 283-513€/ha/year. Because of the lack of existing available data, only 7GB linked to 11/25ES have been estimated. Despite this overall undervaluation, this study offers a value for coastal development policies to take into account.

  10. Transcriptome characterisation and simple sequence repeat marker discovery in the seagrass Posidonia oceanica

    Science.gov (United States)

    D’Esposito, D.; Orrù, L.; Dattolo, E.; Bernardo, L.; Lamontara, A.; Orsini, L.; Serra, I.A; Mazzuca, S.; Procaccini, G.

    2016-01-01

    Posidonia oceanica is an endemic seagrass in the Mediterranean Sea, where it provides important ecosystem services and sustains a rich and diverse ecosystem. P. oceanica meadows extend from the surface to 40 meters depth. With the aim of boosting research in this iconic species, we generated a comprehensive RNA-Seq data set for P. oceanica by sequencing specimens collected at two depths and two times during the day. With this approach we attempted to capture the transcriptional diversity associated with change in light and other depth-related environmental factors. Using this extensive data set we generated gene predictions and identified an extensive catalogue of potential Simple Sequence Repeats (SSR) markers. The data generated here will open new avenues for the analysis of population genetic features and functional variation in P. oceanica. In total, 79,235 contigs were obtained by the assembly of 70,453,120 paired end reads. 43,711 contigs were successfully annotated. A total of 17,436 SSR were identified within 13,912 contigs. PMID:27996971

  11. Uptake of inorganic phosphorus by temperate seagrass beds of Posidonia and Amphibolis in Southern Australia.

    Science.gov (United States)

    Nayar, S

    2015-08-01

    Seagrasses occupy a narrow band of sandy seabed close to the coast and are therefore vulnerable to anthropogenic influences, particularly meadows near large population centres. Over 5000 ha of seagrasses have been lost from Adelaide coastal waters (South Australia) over the past 70 years and much of this loss has been attributed to nutrient inputs from wastewater, industrial and stormwater discharges. This led to the Adelaide Coastal Waters Study to understand processes along the Adelaide metropolitan coast that led to seagrass loss. This study, a subset of the larger ACWS study, used in situ nutrient spike approach to obtain ecologically relevant estimates of seasonal variability in phosphorus uptake in two species of temperate seagrass common to this coast (Amphibolis antarctica and Posidonia angustifolia). Total uptake of phosphorus by biological components in the seagrass beds, viz., seagrass, epiphytes and phytoplankton, was negligible, never exceeding 0.5% of the total resource. Phosphorus uptake rate varied seasonally with higher rates in winter (1.49 μmol P.g(-1) DW.h(-1)) and lower rates in spring (0.70 μmol P.g(-1) DW.h(-1)) for Amphibolis and highest in winter (2.09 μmol P.g(-1) DW.h(-1)) and least in spring (0.14 μmol P.g(-1) DW.h(-1)) for Posidonia. Low biological uptake rates of inorganic phosphorus could be attributed to carbonate sediments and particulates in the water column binding inorganic phosphorus, limiting its availability for biological uptake. From an environmental perspective, seagrass beds in the Adelaide coastal waters account for the assimilation of only 5.4% (19.53 t yr(-1)) of the total anthropogenic inputs of phosphorus.

  12. Posidonia oceanica changes in the Mediterranean sea

    OpenAIRE

    Marbà, Núria; Díaz-Almela, Elena; Duarte, Carlos M.

    2013-01-01

    Methodology: We compiled available data published in peer-review articles and grey literature reports until year 2009 as well as our own unpublished data. We searched for data with the engine ISI web of Knowledge, using the keywords Posidonia oceanica AND (regression OR decline OR progression OR recovery OR status OR cartography OR limits OR cover OR density OR biomass OR dynamics), and conducting a back search of cited papers. More information about the methodology to be found at: Calleja...

  13. Competition between the invasive macrophyte Caulerpa taxifolia and the seagrass Posidonia oceanica: contrasting strategies

    Directory of Open Access Journals (Sweden)

    Pergent-Martini Christine

    2008-12-01

    Full Text Available Abstract Background Plant defense strategy is usually a result of trade-offs between growth and differentiation (i.e. Optimal Defense Theory – ODT, Growth Differentiation Balance hypothesis – GDB, Plant Apparency Theory – PAT. Interaction between the introduced green alga Caulerpa taxifolia and the endemic seagrass Posidonia oceanica in the Mediterranean Sea offers the opportunity to investigate the plausibility of these theories. We have accordingly investigated defense metabolite content and growth year-round, on the basis of an interaction gradient. Results When in competition with P. oceanica, C. taxifolia exhibits increased frond length and decreased Caulerpenyne – CYN content (major terpene compound. In contrast, the length of P. oceanica leaves decreases when in competition with C. taxifolia. However, the turnover is faster, resulting in a reduction of leaf longevity and an increase on the number of leaves produced per year. The primary production is therefore enhanced by the presence of C. taxifolia. While the overall concentration of phenolic compounds does not decline, there is an increase in some phenolic compounds (including ferulic acid and a methyl 12-acetoxyricinoleate and the density of tannin cells. Conclusion Interference between these two species determines the reaction of both, confirming that they compete for space and/or resources. C. taxifolia invests in growth rather than in chemical defense, more or less matching the assumptions of the ODT and/or PAT theories. In contrast, P. oceanica apparently invests in defense rather than growth, as predicted by the GDB hypothesis. However, on the basis of closer scrutiny of our results, the possibility that P. oceanica is successful in finding a compromise between more growth and more defense cannot be ruled out.

  14. A novel methylated sesquiterpene from seagrass Posidonia oceanica (L.) Delile.

    Science.gov (United States)

    Hammami, Saoussen; Salem, Abdelkader Ben; Ashour, Mohamed L; Cheriaa, Jihène; Graziano, Guella; Mighri, Zine

    2013-01-01

    Phytochemical investigation of chloroform extract from the leaves of the marine plant Posidonia oceanica (L.) Delile (Posidoniaceae), yielded posidozinol, a new methylated sesquiterpene along with β-sitosterol and four known fatty acids: palmitic, palmitoleic, oleic and linoleic acids. The structure elucidation has been established on the basis of 1D- and 2D-NMR spectroscopy, GS/MS and ES mass spectrometry. Antibacterial effects of crude extracts from P. oceanica were evaluated against: Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Micrococcus luteus microorganisms.

  15. Edge Effects along a Seagrass Margin Result in an Increased Grazing Risk on Posidonia australis Transplants

    Science.gov (United States)

    Statton, John; Gustin-Craig, Samuel; Dixon, Kingsley W.; Kendrick, Gary A.

    2015-01-01

    A key issue in habitat restoration are the changes in ecological processes that occur when fragments of habitat are lost, resulting in the persistence of habitat-degraded margins. Margins often create or enhance opportunities for negative plant-herbivore interactions, preventing natural or assisted re-establishment of native vegetation into the degraded area. However, at some distance from the habitat margin these negative interactions may relax. Here, we posit that the intensity of species interactions in a fragmented Posidonia australis seagrass meadow may be spatially dependent on proximity to the seagrass habitat edge, whereby the risk of grazing is high and the probability of survival of seagrass transplants is low. To test this, transplants were planted 2 m within the meadow, on the meadow edge at 0m, and at 2m, 10m, 30m, 50m and 100m distance from the edge of the seagrass meadow into the unvegetated sand sheet. There was an enhanced grazing risk 0-10m from the edge, but decreased sharply with increasing distances (>30m). Yet, the risk of grazing was minimal inside the seagrass meadow, indicating that grazers may use the seagrass meadow for refuge but are not actively grazing within it. The relationship between short-term herbivory risk and long-term survival was not straightforward, suggesting that other environmental filters are also affecting survival of P. australis transplants within the study area. We found that daily probability of herbivory was predictable and operating over a small spatial scale at the edge of a large, intact seagrass meadow. These findings highlight the risk from herbivory can be high, and a potential contributing factor to seagrass establishment in restoration programs. PMID:26465926

  16. Edge Effects along a Seagrass Margin Result in an Increased Grazing Risk on Posidonia australis Transplants.

    Science.gov (United States)

    Statton, John; Gustin-Craig, Samuel; Dixon, Kingsley W; Kendrick, Gary A

    2015-01-01

    A key issue in habitat restoration are the changes in ecological processes that occur when fragments of habitat are lost, resulting in the persistence of habitat-degraded margins. Margins often create or enhance opportunities for negative plant-herbivore interactions, preventing natural or assisted re-establishment of native vegetation into the degraded area. However, at some distance from the habitat margin these negative interactions may relax. Here, we posit that the intensity of species interactions in a fragmented Posidonia australis seagrass meadow may be spatially dependent on proximity to the seagrass habitat edge, whereby the risk of grazing is high and the probability of survival of seagrass transplants is low. To test this, transplants were planted 2 m within the meadow, on the meadow edge at 0m, and at 2m, 10m, 30m, 50m and 100m distance from the edge of the seagrass meadow into the unvegetated sand sheet. There was an enhanced grazing risk 0-10m from the edge, but decreased sharply with increasing distances (>30m). Yet, the risk of grazing was minimal inside the seagrass meadow, indicating that grazers may use the seagrass meadow for refuge but are not actively grazing within it. The relationship between short-term herbivory risk and long-term survival was not straightforward, suggesting that other environmental filters are also affecting survival of P. australis transplants within the study area. We found that daily probability of herbivory was predictable and operating over a small spatial scale at the edge of a large, intact seagrass meadow. These findings highlight the risk from herbivory can be high, and a potential contributing factor to seagrass establishment in restoration programs.

  17. Climate change and Mediterranean seagrass meadows: a synopsis for environmental managers

    Directory of Open Access Journals (Sweden)

    G. PERGENT

    2014-07-01

    Full Text Available This synopsis focuses on the effects of climate change on Mediterranean seagrasses, and associated communities, and on the contribution of the main species, Posidonia oceanica, to the mitigation of climate change effects through its role of sequestering carbon dioxide. Whilst the regression of seagrass meadows is well documented, generally linked to anthropogenic pressures, global warming could be a cause of new significant regressions, notably linked to the introduction of exotic species, the rise of Sea-Surface Temperature (SST, and relative sea level. Seagrass communities could also be affected by climate change through the replacement of seagrass species having high structural complexity by species of lower complexity and even by opportunistic introduced species. Although it is currently very difficult to predict the consequences of these alterations and their cascade effects, two main conflicting trends in the functioning of seagrass ecosystems that could occur are acceleration of the herbivore pathway or of the detritivore pathway. The mean net primary production of the dominant species, Posidonia oceanica, is relatively high and can be estimated to range between 92.5 to 144.7 g C m-2 a-1. Around 27% of the total carbon fixed by this species enters the sedimentary pathway leading to formation, over millennia, of highly organic deposits rich in refractory carbon. At the Mediterranean scale, the sequestration rate might reach 1.09 Tg C a-1. The amount of this stored carbon is estimated to range from 71 to 273 kg C m-2, which when considered at the Mediterranean scale would represent 11 to 42% of the CO2 emissions produced by Mediterranean countries since the beginning of the Industrial Revolution. The greatest value of the P. oceanica ecosystem, in the context of mitigation of global climate change, is linked to this vast long-term carbon stock accumulated over the millennia, and therefore, efforts should be focused on preserving the

  18. Chemoreception of the Seagrass Posidonia Oceanica by Benthic Invertebrates is Altered by Seawater Acidification.

    Science.gov (United States)

    Zupo, Valerio; Maibam, Chingoileima; Buia, Maria Cristina; Gambi, Maria Cristina; Patti, Francesco Paolo; Scipione, Maria Beatrice; Lorenti, Maurizio; Fink, Patrick

    2015-08-01

    Several plants and invertebrates interact and communicate by means of volatile organic compounds (VOCs). These compounds may play the role of infochemicals, being able to carry complex information to selected species, thus mediating inter- or intra-specific communications. Volatile organic compounds derived from the wounding of marine diatoms, for example, carry information for several benthic and planktonic invertebrates. Although the ecological importance of VOCs has been demonstrated, both in terrestrial plants and in marine microalgae, their role as infochemicals has not been demonstrated in seagrasses. In addition, benthic communities, even the most complex and resilient, as those associated to seagrass meadows, are affected by ocean acidification at various levels. Therefore, the acidification of oceans could produce interference in the way seagrass-associated invertebrates recognize and choose their specific environments. We simulated the wounding of Posidonia oceanica leaves collected at two sites (a control site at normal pH, and a naturally acidified site) off the Island of Ischia (Gulf of Naples, Italy). We extracted the VOCs and tested a set of 13 species of associated invertebrates for their specific chemotactic responses in order to determine if: a) seagrasses produce VOCs playing the role of infochemicals, and b) their effects can be altered by seawater pH. Our results indicate that several invertebrates recognize the odor of wounded P. oceanica leaves, especially those strictly associated to the leaf stratum of the seagrass. Their chemotactic reactions may be modulated by the seawater pH, thus impairing the chemical communications in seagrass-associated communities in acidified conditions. In fact, 54% of the tested species exhibited a changed behavioral response in acidified waters (pH 7.7). Furthermore, the differences observed in the abundance of invertebrates, in natural vs. acidified field conditions, are in agreement with these behavioral

  19. Differences Among Fish Assemblages Associated with Nearshore Posidonia oceanica Seagrass Beds, Rocky algal Reefs and Unvegetated Sand Habitats in the Adriatic Sea

    Science.gov (United States)

    Guidetti, P.

    2000-04-01

    Fish assemblages associated with nearshore Posidonia oceanica seagrass beds, rocky-algal reefs and unvegetated sandy substrates were studied at two sampling localities, Otranto (Apulian coast) and S. Domino (Tremiti Islands), located in the Southern and Central Adriatic Seas (Mediterranean Sea), respectively. Data were collected in situ by using non-destructive diver visual census methodology. A higher species richness and fish density were observed over the Posidonia seagrass and, in turn, the rocky-algal reef and unvegetated sand habitats. Planktivorous fish species ( Spicara maena, Spicara smaris and Chromis chromis) showing patchy distributions were dominant in terms of abundance at both localities. The two former species did not show any particular habitat preference, while C. chromis was common over both the Posidonia and rocky-algal habitats and was only occasionally recorded over sand. Symphodus ocellatus , Diplodus annularis and Spondyliosoma cantharus were the most common species in the P. oceanica seagrass beds. Symphodus roissali, Symphodus tinca and Diplodus sargus were mainly associated with the rocky-algal reef habitats, while other species, such as Gymnammodytes cicerellus, Lithognathus mormyrus , Gobius geniporus, Mullus barbatus and Uranoscopus scaber, were censused over the unvegetated sand habitats. A cluster analysis performed on the entire fish density data set showed distinct groupings for seagrass, rocky-algal and bare sand fish assemblages, regardless of season and sampling site. Fish assemblages in the more structured (seagrass and rocky-algal reef) habitats were relatively similar to each other but quite different from those of the unstructured bare sands. With regard to small-sized specimens (juvenile stages including recruits), those of S. ocellatus, Symphodus mediterraneus, Serranus cabrilla, D. annularis, S. cantharus and Sarpa salpa were mainly censused over P. oceanica beds, while juveniles of C. chromis inhabited predominantly

  20. Endophytic bacterial community of a Mediterranean marine angiosperm (Posidonia oceanica

    Directory of Open Access Journals (Sweden)

    Neus eGarcias-Bonet

    2012-09-01

    Full Text Available Bacterial endophytes are crucial for the survival of many terrestrial plants, but little is known about the presence and importance of bacterial endophytes of marine plants. We conducted a survey of the endophytic bacterial community of the long-living Mediterranean marine angiosperm Posidonia oceanica in surface-sterilized tissues (roots, rhizomes and leaves by DGGE. A total of 26 Posidonia oceanica meadows around the Balearic Islands were sampled, and the band patterns obtained for each meadow were compared for the three sampled tissues. Endophytic bacterial sequences were detected in most of the samples analyzed. A total of 34 OTUs (Operational Taxonomic Units were detected. The main OTUs of endophytic bacteria present in P. oceanica tissues belonged primarily to Proteobacteria (α, γ and δ subclasses and Bacteroidetes. The OTUs found in roots significantly differed from those of rhizomes and leaves. Moreover, some OTUs were found to be associated to each type of tissue. Bipartite network analysis revealed differences in the bacterial endophyte communities present on different islands. The results of this study provide a pioneering step toward the characterization of the endophytic bacterial community associated with tissues of a marine angiosperm and reveal the presence of bacterial endophytes that differed among locations and tissue types.

  1. Population structure and secondary production of Siriella clausii, a dominant detritus feeding mysid in Posidonia oceanica meadows (W Mediterranean Sea)

    Science.gov (United States)

    Barberá, Carmen; Sanchez-Jerez, Pablo; Sorbe, Jean Claude

    2013-10-01

    Temporal trends in abundance, demographic structure of the population and secondary production of Siriella clausii were studied at three different sectors of Posidonia oceanica meadows in the SE Iberian Peninsula, with different levels of habitat complexity. Secondary production was calculated through three methods widely employed in marine invertebrates: the Hynes method (based on demographic structure data) and models by Morin-Bourassa and Brey (based on biomass data). This filter/grazer and detritus feeder is the most abundant mysid in P. oceanica seagrass meadows in the Mediterranean. The population structure was similar in the three sectors, but the temporal pattern of abundance was different, at times even opposite. This pattern may be related to the aggregated spatial distribution, metapopulation dynamics or stochastic factors, but other potential factors could be involved, such as habitat features or predation rates. The values of production oscillated between 25 and 60 mgAFDW/m2/year, depending on the calculation method that was applied, and showed differences between sites and seagrass complexity. The present values are intermediate between those characterising highly productive systems, such as estuaries, and systems of limited productivity (bathyal habitats). Compared to other peracarids, mysid production is greater than that of isopods and less than amphipod production. This is possibly related to the life cycle and reproductive strategies. Detritus feeders such as S. clausii may play an important trophic role due their capacity to use as food the biomass associated to detritus, which constitutes larges reservoirs of carbon derived from seagrass primary production.

  2. Seagrass on the rocks: Posidonia oceanica settled on shallow-water hard substrata withstands wave stress beyond predictions

    Science.gov (United States)

    Montefalcone, Monica; Vacchi, Matteo; Carbone, Cristina; Cabella, Roberto; Schiaffino, Chiara Francesca; Elter, Franco Marco; Morri, Carla; Bianchi, Carlo Nike; Ferrari, Marco

    2016-10-01

    A multidisciplinary approach was applied to investigate the role of abiotic constraints in the settlement of Posidonia oceanica on shallow rocks in two coastal areas of the Ligurian Sea (Italy, NW Mediterranean). Meadows developed very shallow upper limits, at 1.5 m depth in both areas, and with a distinctive morphology of stripes growing on rocky outcrops orthogonal to the coastline. Application of a predictive model to indicate the reference condition zone for the meadow upper limit, already validated on meadows developing on soft-bottoms, was not adequate for these rocky substrata as the meadow upper limits were found shallower than model predictions (>5 m depth). Geological and geomorphological characteristics of the rocky shores were analysed through geomechanic and petrographic analyses (i.e. thin sections, SEM analyses, rock hardness tests) whilst the shape and the features of the meadows (i.e. shoot density and maximum leaf length) were assessed through scuba diving surveys. Among the different lithotypes occurring at the sites in the alternating and interbedded outcrops, P. oceanica was passively selected (i.e. due to the seedlings survival and settlement there) on the strongest (i.e. less erodible) lithotypes, whilst the comparatively weaker and more erodible rocks remained unvegetated and covered by a layer of soft-sediments. P. oceanica, settling on specific rocky substrata with favourable lithological and geomechanical characteristics, is able to establish outside the theoretical reference zone predicted by the model for soft sediments due to greater attachment strength and possible resistance to hydrodynamic forces. Combining biological, ecological, mineralogical, geological and geomorphological approaches was effective for explaining the primary role of substratum nature in the spatial variability of seagrass meadows, with geomechanical and lithological characteristics of the rocks being equally important abiotic factors than sedimentological

  3. The role and contribution of the seagrass Posidonia oceanica (L.) Delile organic matter for secondary consumers as revealed by carbon and nitrogen stable isotope analysis

    Science.gov (United States)

    Vizzini, S.; Sarà, G.; Michener, R. H.; Mazzola, A.

    2002-08-01

    The δ 13C and δ 15N values of primary producers and consumers were studied to obtain information on the trophic role of Posidonia oceanica L. Delile, the dominant primary producer, in a Mediterranean shallow environment (the Stagnone di Marsala, western Sicily). δ 13C strongly discriminated between pelagic and benthic pathways, with the former based on phytoplankton and the latter on a mixed pool of seagrass detritus, epiphytes and benthic algae as carbon sources. A particularly important trophic role appears to be performed by the vegetal epiphytic community on seagrass leaves (δ 13C = -14.9 ± 0.1‰), which supports most of the faunal seagrass community (i.e. Amphipoda, Isopoda, Tanaidacea; δ 13C = -14.9 ± 0.1‰, -12.5 ± 0.1‰ and -14.8 ± 1.0‰, respectively). Although P. oceanica (δ 13C = -11.3 ± 0.3‰) does not seem to be utilised by consumers via grazing (apart from a few Palaemonidae species with δ 13C value of -10.8 ± 1.8‰), its trophic role may be via detritus. P. oceanica detritus may be exploited as a carbon source by small detritivore invertebrates, and above all seems to be exploited as a nitrogen reservoir by both bottom and water column consumers determining benthic-pelagic coupling. At least three trophic levels were detected in both the pelagic (mixture of phytoplankton and cyanobacteria, zooplankton, juvenile transient fish) and benthic (sedimentary organic matter and epiphytes, small seagrass-associated invertebrates, larger invertebrates and adult resident fish) pathways.

  4. Meiofauna communities, nematode diversity and C degradation rates in seagrass (Posidonia oceanica L.) and unvegetated sediments invaded by the algae Caulerpa cylindracea (Sonder).

    Science.gov (United States)

    Pusceddu, Antonio; Fraschetti, Simona; Scopa, Mariaspina; Rizzo, Lucia; Danovaro, Roberto

    2016-08-01

    We investigated meiofauna and sedimentary C cycling in seagrass (Posidonia oceanica) and unvegetated sediments invaded and not invaded by the non-indigenous tropical algae Caulerpa cylindracea. In both habitats, invaded sediments were characterized by higher organic matter contents. No effect was observed for prokaryotes and C degradation rates. In seagrass sediments, C turnover in invaded beds was about half that in not invaded ones. Meiofaunal communities varied significantly among invaded and not invaded grounds only in bare sediments. In both habitats, nematode species richness and assemblage composition were not affected by the algae. The effect of C. cylindracea on the turnover and nestedness components of the Jaccard dissimilarity varied between the two habitats. We show that the presence of C. cylindracea gives rise to variable consequences on meiofauna biodiversity and C cycling in different habitats. We conclude that further studies across different habitats and ecological components are needed to ultimately understand and predict the consequences of C. cylindracea invasion in shallow Mediterranean ecosystems.

  5. Physiological responses of the seagrass Posidonia oceanica as indicators of fish farm impact

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    Perez, Marta [Departament d' Ecologia, Universitat de Barcelona Avda. Diagonal 645, 08028 Barcelona (Spain); Garcia, Tania [Departament d' Ecologia, Universitat de Barcelona Avda. Diagonal 645, 08028 Barcelona (Spain)], E-mail: irulagun@hotmail.com; Invers, Olga [Departament d' Ecologia, Universitat de Barcelona Avda. Diagonal 645, 08028 Barcelona (Spain); Ruiz, Juan Manuel [Instituto Espanol de Oceanografia C/Varadero 1, 30740 San Pedro del Pinatar, Murcia (Spain)

    2008-05-15

    The development of aquaculture along the Mediterranean coastline degrades the marine environment, in particular Posidonia oceanica meadows, which, in extreme cases, show high mortality. Here we studied the effects of organic matter and nutrient input from the effluents of three fish farms, located along the Mediterranean coast, on P. oceanica physiology. For this purpose, we measured physiological variables such as total nitrogen (N) content, free amino acid (FAA) concentration and composition, N stable isotope ratio ({delta}{sup 15}N), total phosphorus (P) content and total non-structural carbohydrate (TNC) content in plant tissues and epiphytes affected by organic discharges (highly impacted stations: HI, and less impacted stations: LI) and compared these results with those obtained in references sites (control stations: C). For all the descriptors analyzed in P. oceanica epiphytes, the values recorded in the vicinity of cages were, in general, much higher than those in C. Leaves did not respond consistently in any case. Total N content and {delta}{sup 15}N in epiphytes together with the total P content in rhizomes and epiphytes were the physiological descriptors that showed the most consistent responses to fish farm effluents. On the basis of these observations, we conclude that fish farm activities strongly affect the physiological parameters of nearby P. oceanica meadows. We propose that changes in these physiological parameters may be useful indicators of marine environmental degradation in studies that monitor the effects of fish farming.

  6. Physiological responses of the seagrass Posidonia oceanica as indicators of fish farm impact.

    Science.gov (United States)

    Pérez, Marta; García, Tania; Invers, Olga; Ruiz, Juan Manuel

    2008-05-01

    The development of aquaculture along the Mediterranean coastline degrades the marine environment, in particular Posidonia oceanica meadows, which, in extreme cases, show high mortality. Here we studied the effects of organic matter and nutrient input from the effluents of three fish farms, located along the Mediterranean coast, on P. oceanica physiology. For this purpose, we measured physiological variables such as total nitrogen (N) content, free amino acid (FAA) concentration and composition, N stable isotope ratio (delta 15N), total phosphorus (P) content and total non-structural carbohydrate (TNC) content in plant tissues and epiphytes affected by organic discharges (highly impacted stations: HI, and less impacted stations: LI) and compared these results with those obtained in references sites (control stations: C). For all the descriptors analyzed in P. oceanica epiphytes, the values recorded in the vicinity of cages were, in general, much higher than those in C. Leaves did not respond consistently in any case. Total N content and delta 15N in epiphytes together with the total P content in rhizomes and epiphytes were the physiological descriptors that showed the most consistent responses to fish farm effluents. On the basis of these observations, we conclude that fish farm activities strongly affect the physiological parameters of nearby P. oceanica meadows. We propose that changes in these physiological parameters may be useful indicators of marine environmental degradation in studies that monitor the effects of fish farming.

  7. Seasonal and inter-annual variations of community metabolism rates of a Posidonia oceanica seagrass meadow

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    Champenois, W.; Borges, A. V.

    2012-04-01

    We report gross primary production (GPP), community respiration (CR), and net community production (NCP) over Posidonia oceanica meadow at 10 m in Corsica (Bay of Revellata) based on the open water O2 mass balance from a data-set of hourly measurements with an array of three O2 optodes deployed from August 2006 to October 2009. The method was checked by comparison with discrete measurements of metabolic rates derived from benthic chamber incubations also based on the diel change of O2. This comparison was satisfactory and actually highlights the potential caveats of benthic incubation measurements related to O2 accumulation in small chambers leading to photorespiration, and an under-estimation of GPP. Our data confirmed previous P. oceanica meadows GPP and CR values, strong seasonal variations, and net autotrophy. High resolution data revealed strong inter-annual variability, with a decrease of GPP by 35% and NCP by 87% during 2006-2007 characterized by a mild and less stormy winter compared 2007-2008 and 2008-2009. P. oceanica meadows are then expected to decrease export of organic carbon to adjacent communities (decrease of NCP), since a decrease in frequency and intensity of marine storms is expected in future in the Mediterranean Sea, due to a northward shift of the Atlantic storm track.

  8. Physiological and molecular evidence of differential short-term heat tolerance in Mediterranean seagrasses

    Science.gov (United States)

    Marín-Guirao, Lazaro; Ruiz, Juan M.; Dattolo, Emanuela; Garcia-Munoz, Rocio; Procaccini, Gabriele

    2016-06-01

    The increase in extreme heat events associated to global warming threatens seagrass ecosystems, likely by affecting key plant physiological processes such as photosynthesis and respiration. Understanding species’ ability to acclimate to warming is crucial to better predict their future trends. Here, we study tolerance to warming in two key Mediterranean seagrasses, Posidonia oceanica and Cymodocea nodosa. Stress responses of shallow and deep plants were followed during and after short-term heat exposure in mesocosms by coupling photo-physiological measures with analysis of expression of photosynthesis and stress-related genes. Contrasting tolerance and capacity to heat acclimation were shown by shallow and deep P. oceanica ecotypes. While shallow plants acclimated through respiratory homeostasis and activation of photo-protective mechanisms, deep ones experienced photosynthetic injury and impaired carbon balance. This suggests that P. oceanica ecotypes are thermally adapted to local conditions and that Mediterranean warming will likely diversely affect deep and shallow meadow stands. On the other hand, contrasting mechanisms of heat-acclimation were adopted by the two species. P. oceanica regulates photosynthesis and respiration at the level of control plants while C. nodosa balances both processes at enhanced rates. These acclimation discrepancies are discussed in relation to inherent attributes of the two species.

  9. Marine Algae and Seagrasses of Hatay (Mediterranean, Turkey)

    OpenAIRE

    Aysel, V.; Erdugan, H.; Okudan, E. S.

    2015-01-01

    Abstract In this research, marine algae and seagrasses were investigated in the upper infralittoral zone of Hatay (Turkish Mediterranean coasts). A total of 377 algae and 5 seagrasses were determined. 30 of them belong to blue-green algae (Cyanophyceae), 201 to red algae [Rhodellophyceae (2), Compsopogonophyceae (2), Bangiophyceae (5), Florideophyceae (192)], 73 to brown algae (Fucophyceae), 73 to green algae [Chlorophyceae (5), Ulvophyceae (19), Trentepohliophyceae (1), Cladophorophyceae (24...

  10. Marine Algae and Seagrasses of Hatay (Mediterranean, Turkey)

    OpenAIRE

    Aysel, V.; Erdugan, H.; Okudan, E. S.

    2006-01-01

    Abstract In this research, marine algae and seagrasses were investigated in the upper infralittoral zone of Hatay (Turkish Mediterranean coasts). A total of 377 algae and 5 seagrasses were determined. 30 of them belong to blue-green algae (Cyanophyceae), 201 to red algae [Rhodellophyceae (2), Compsopogonophyceae (2), Bangiophyceae (5), Florideophyceae (192)], 73 to brown algae (Fucophyceae), 73 to green algae [Chlorophyceae (5), Ulvophyceae (19), Trentepohliophyceae (1), Cladophorophyceae (24...

  11. Ocean Color Products Supporting the Assessment of Good Environmental Status: Development of a Spatial Distribution Model for the Seagrass Posidonia Oceanica (L.) Delille, 1813

    Science.gov (United States)

    Zucchetta, M.; Taji, M. A.; Mangin, A.; Pastres, R.

    2015-12-01

    Posidonia oceanica (L.) Delile, 1813 is a seagrass species endemic to the Mediterranean Sea, which is considered as one of the key habitats of the coastal areas. This species forms large meadows sensitive to several anthropogenic pressures, that can be regarded as indicators of environment quality in coastal environments and its distributional patterns should be take into account when evaluating the Environmental Status following the Ecosystem approach promoted by the Mediterranean Action Plan of UNEP and the EU Marine Strategy Framework Directive (2008/56/EC). The aim of this study was to develop a Species Distribution Model for P. oceanica, to be applied to the whole Mediterranean North African coast, in order to obtain an estimation of the potential distribution of this species in the region to be considered as an indicator for the assessment of good Environmental Status. As the study area is a data-poor zone with regard to seagrass distribution (i.e. only for some areas detailed distribution maps are available), the Species Distribution Model (SDM) was calibrated using high resolution data from 5 Mediterranean sites, located in Italy and Spain and validated using available data from the North African coast. Usually, when developing SDMs species occupancy data is available at coarser resolution than the information of environmental variables, and thus has to be downscaled at the appropriate grain to be coupled to the environmental conditions. Tackling the case of P. oceanica we had to face the opposite problem: the quality (in terms of resolution) of the information on seagrass distribution is generally very high compared to the environmental data available over large scale in marine domains (e.g. global bathymetry data). The high resolution application and the model transfer (from calibration areas to North African coast) was possible taking advantage of Ocean Color products: the probability of presence of the species in a given area was modelled using a

  12. Relationships between trace elements in Posidonia oceanica shoots and in sediment fractions along Latium coasts (northwestern Mediterranean Sea).

    Science.gov (United States)

    Bravo, I; Focaracci, F; Cerfolli, F; Papetti, P

    2016-03-01

    The Mediterranean endemic seagrass Posidonia oceanica is widely used as a sensitive bioindicator of trace elements (TEs) in the coastal environment. Therefore, a bulk of data exist on TE levels from impacted versus unpolluted sites while only recent studies started comparing TE accumulation in plant compartments versus both water column and sediment characteristics. In this study, six TEs (As, Cd, Cr, Cu, Ni, Pb) were analyzed in P. oceanica shoots related to depth (-10 and -20 m) and to TE concentrations in the different grain size fractions of the sediment, from two Sites of Community interest (SIC) in the central Tyrrhenian Sea. TE concentrations in both shoots and sediment were generally low, except for Cr. Cu was the only element showing significantly different concentrations at the two sites while As differed significantly between samples taken at different depths. TE concentrations in the unsieved sediment were found uncorrelated to TEs in shoots except for the important nutrient Cu (positive correlation). The finest sediment fractions were enriched in TEs and significantly correlated to Cd, Cr, Cu, and Ni concentrations in the shoots.

  13. Metal contamination of Posidonia oceanica meadows along the Corsican coastline (Mediterranean).

    Science.gov (United States)

    Lafabrie, C; Pergent-Martini, C; Pergent, G

    2008-01-01

    The aim of this study is to determine metal (Cd, Co, Cr, Hg, Ni, Pb) concentrations in Posidonia oceanica tissues along the Corsican coastline. The results show that except for Cr, all the metals are preferentially accumulated in the blades; this is particularly interesting as it means that future metal analyses may be carried out only on the blades avoiding thus the removal of the shoots. Moreover, they show that metal concentrations may reflect the "background noise" of the Mediterranean Sea. Station 15 (Canari) can however be distinguished from the others due to its high Co, Cr and Ni concentrations. This result may be related to the presence of a previous asbestos mine, located near this station. Therefore, this study reinforces the usefulness and the relevance of Posidonia oceanica as a tracer of spatial metal contamination and as an interesting tool for water quality evaluation.

  14. Trace metal concentrations in Posidonia oceanica of North Corsica (northwestern Mediterranean Sea: use as a biological monitor?

    Directory of Open Access Journals (Sweden)

    Gosselin Marc

    2006-09-01

    Full Text Available Abstract Background Within semi-closed areas like the Mediterranean Sea, anthropic wastes tend to concentrate in the environment. Metals, in particular, are known to persist in the environment and can affect human health due to accumulation in the food chain. The seagrass Posidonia oceanica, widely found in Mediterranean coastal waters, has been chosen as a "sentinel" to quantify the distribution of such pollutants within the marine environment. Using a technique similar to dendrochronology in trees, it can act as an indicator of pollutant levels over a timeframe of several months to years. In the present study, we measured and compared the levels of eight trace metals (Cr, Ni, Cu, Zn, As, Se, Cd, and Pb in sheaths dated by lepidochronology and in leaves of shoots sampled from P. oceanica meadows collected from six offshore sites in northern Corsica between 1988 and 2004; in the aim to determine 1 the spatial and 2 temporal variations of these metals in these areas and 3 to compared these two types of tissues. Results We found low trace metal concentrations with no increase over the last decade, confirming the potential use of Corsican seagrass beds as reference sites for the Mediterranean Sea. Temporal trends of trace metal concentrations in sheaths were not significant for Cr, Ni, Cu, As or Se, but Zn, Cd, and Pb levels decreased, probably due to the reduced anthropic use of these metals. Similar temporal trends between Cu levels in leaves (living tissue and in sheaths (dead tissue demonstrated that lepidochronology linked with Cu monitoring is effective for surveying the temporal variability of this metal. Conclusion Leaves of P. oceanica can give an indication of the metal concentration in the environment over a short time period (months with good accuracy. On the contrary, sheaths, which gave an indication of changes over long time periods (decades, seem to be less sensitive to variations in the metal concentration in the environment

  15. The effect of salinity increase on the photosynthesis, growth and survival of the Mediterranean seagrass Cymodocea nodosa

    Science.gov (United States)

    Sandoval-Gil, José M.; Marín-Guirao, Lázaro; Ruiz, Juan M.

    2012-12-01

    . nodosa has a higher tolerance to hypersaline conditions than the highly sensitive Posidonia oceanica, the other dominant Mediterranean seagrass, which is limited to marine environments with stable salinities.

  16. Global warming enhances sulphide stress in a key seagrass species (NW Mediterranean).

    Science.gov (United States)

    García, Rosa; Holmer, Marianne; Duarte, Carlos M; Marbà, Núria

    2013-12-01

    The build-up of sulphide concentrations in sediments, resulting from high inputs of organic matter and the mineralization through sulphate reduction, can be lethal to the benthos. Sulphate reduction is temperature dependent, thus global warming may contribute to even higher sulphide concentrations and benthos mortality. The seagrass Posidonia oceanica is very sensitive to sulphide stress. Hence, if concentrations build up with global warming, this key Mediterranean species could be seriously endangered. An 8-year monitoring of daily seawater temperature, the sulphur isotopic signatures of water (δ(34)S(water)), sediment (δ(34)SCRS ) and P. oceanica leaf tissue (δ(34)S(leaves)), along with total sulphur in leaves (TS(leaves)) and annual net population growth along the coast of the Balearic archipelago (Western Mediterranean) allowed us to determine if warming triggers P. oceanica sulphide stress and constrains seagrass survival. From the isotopic S signatures, we estimated sulphide intrusion into the leaves (F(sulphide)) and sulphur incorporation into the leaves from sedimentary sulphides (SS(leaves)). We observed lower δ(34)S(leaves), higher F(sulphide) and SS(leaves) coinciding with a 6-year period when two heat waves were recorded. Warming triggered sulphide stress as evidenced by the negative temperature dependence of δ(34)S(leaves) and the positive one of F(sulphide), TS(leaves) and SS(leaves). Lower P. oceanica net population growth rates were directly related to higher contents of TS(leaves). At equivalent annual maximum sea surface water temperature (SST(max)), deep meadows were less affected by sulphide intrusion than shallow ones. Thus, water depth acts as a protecting mechanism against sulphide intrusion. However, water depth would be insufficient to buffer seagrass sulphide stress triggered by Mediterranean seawater summer temperatures projected for the end of the 21st century even under scenarios of moderate greenhouse gas emissions, A1B

  17. Interaction between Posidonia oceanica meadows upper limit and hydrodynamics of four Mediterranean beaches

    Science.gov (United States)

    De Muro, Sandro; Ruju, Andrea; Buosi, Carla; Porta, Marco; Passarella, Marinella; Ibba, Angelo

    2017-04-01

    Posidonia oceanica meadow is considered to play an important role in the coastal geomorphology of Mediterranean beach systems. In particular, the importance of the meadow in protecting the coastline from erosion is well-recognized. Waves are attenuated by greater friction across seagrass meadows, which have the capacity to reduce water flow and therefore increase sediment deposition and accumulation as well as beach stability. The P. oceanica meadow upper limit usually occurs within the most dynamic zone of the beach system. Considering the great attention paid in the literature to the connection between the growth of P. oceanica and coastal hydrodynamics (Infantes et al., 2009; Vacchi et al., 2014; De Muro et al., 2016, 2017), this study aims at extending the previous work by investigating the combined influence of hydrodynamic parameters (e.g., wave-induced main currents and wave orbital velocity at the bottom) and different types of sea bottom (e.g., soft sediment, rocky substrates) on the position of the upper limit of the P. oceanica meadow. We applied this approach to 4 Mediterranean beach systems located on the Sardinian coastline (3 on the South and 1 on the North) and characterized by a wide range of orientations and incoming wave conditions. On these beaches, the extension of the P. oceanica meadows and the bathymetry have been obtained through detailed surveying campaigns and aerial photo analysis. In addition, high spatial resolution wave hydrodynamics have been reconstructed by running numerical simulations with Delft 3D. Offshore wave climate has been reconstructed by using measured datasets for those beaches that have a nearby buoy whose dataset is representative of the incoming wave conditions for that particular stretch of coast. Whereas, for those beaches with no availability of a representative measured dataset, wave climate has been analyzed from the NOAA hindcast dataset. From the whole range of incoming wave directions in deep waters, we

  18. A Comparison of Abundance and Diversity of Epiphytic Microalgal Assemblages on the Leaves of the Seagrasses Posidonia oceanica (L. and Cymodocea nodosa (Ucria Asch in Eastern Tunisia

    Directory of Open Access Journals (Sweden)

    Lotfi Mabrouk

    2014-01-01

    Full Text Available We studied spatial patterns in assemblages of epiphytic microalgae on the leaves of two seagrass species with different morphologies and longevity, Cymodocea nodosa and Posidonia oceanica, which cooccur in Chebba in Eastern Tunisia. Epiphyte assemblages were described for each species in summer. Epiphyte microalgal assemblages were more abundant on the leaves of C. nodosa but more diversified on the leaves of P. oceanica. We suggest that the differences in species composition and abundance between those seagrass species may reflect an interaction of timescales of seagrass longevity with timescales of algal reproductive biology. Short-lived C. nodosa was dominated by fast growing species such as the cyanobacteria species Oscillatoria sp., while P. oceanica leaves were colonized by more mature and diversified species such as Prorocentrales. Local environmental conditions (hydrodynamics, light penetration, host characteristics (meadow type, shapes forms of leaves, life span, and growth rate, and grazing effect seem also to be responsible for these dissimilarities in epiphytic microalgae communities.

  19. Evolution and vitality of seagrasses in a Mediterranean lagoon.

    Science.gov (United States)

    Ferrat, Lila; Fernandez, C; Pasqualini, V; Pergent, G; Pergent-Martini, C

    2003-08-01

    Despite their registration on the list of the Ramsar convention sites, the Mediterranean lagoons rarely beneficiate of an effective protection, and are particularly sensitive to environmental quality. A control of these wetlands needs the creation of an inventory of knowledge for the concerned environment. In this perspective, the seagrass beds were followed up in the coastal lagoon of Urbino (Corse, France) since 1990. A cartographic study was carried out by remote sensing of aerial photography. Temporal evolution of the seagrass beds (Cymodocea nodosa principally) allows to determine the vitality of these structures. A comparison of the surface areas occupied by Cymodocea nodosa, between 1990 and 1999, did not allow seeing any significant evolution. However, some variations appear like biotopes all more fragile and coveted as the Mediterranean coastal fringe is straight and is the privileged site of appear in the localization of the beds, due to the modification of environmental conditions in the lagoon.

  20. Depth-specific fluctuations of gene expression and protein abundance modulate the photophysiology in the seagrass Posidonia oceanica

    Science.gov (United States)

    Procaccini, Gabriele; Ruocco, Miriam; Marín-Guirao, Lázaro; Dattolo, Emanuela; Brunet, Christophe; D’Esposito, Daniela; Lauritano, Chiara; Mazzuca, Silvia; Serra, Ilia Anna; Bernardo, Letizia; Piro, Amalia; Beer, Sven; Björk, Mats; Gullström, Martin; Buapet, Pimchanok; Rasmusson, Lina M.; Felisberto, Paulo; Gobert, Sylvie; Runcie, John W.; Silva, João; Olivé, Irene; Costa, Monya M.; Barrote, Isabel; Santos, Rui

    2017-01-01

    Here we present the results of a multiple organizational level analysis conceived to identify acclimative/adaptive strategies exhibited by the seagrass Posidonia oceanica to the daily fluctuations in the light environment, at contrasting depths. We assessed changes in photophysiological parameters, leaf respiration, pigments, and protein and mRNA expression levels. The results show that the diel oscillations of P. oceanica photophysiological and respiratory responses were related to transcripts and proteins expression of the genes involved in those processes and that there was a response asynchrony between shallow and deep plants probably caused by the strong differences in the light environment. The photochemical pathway of energy use was more effective in shallow plants due to higher light availability, but these plants needed more investment in photoprotection and photorepair, requiring higher translation and protein synthesis than deep plants. The genetic differentiation between deep and shallow stands suggests the existence of locally adapted genotypes to contrasting light environments. The depth-specific diel rhythms of photosynthetic and respiratory processes, from molecular to physiological levels, must be considered in the management and conservation of these key coastal ecosystems. PMID:28211527

  1. Depth-specific fluctuations of gene expression and protein abundance modulate the photophysiology in the seagrass Posidonia oceanica

    Science.gov (United States)

    Procaccini, Gabriele; Ruocco, Miriam; Marín-Guirao, Lázaro; Dattolo, Emanuela; Brunet, Christophe; D’Esposito, Daniela; Lauritano, Chiara; Mazzuca, Silvia; Serra, Ilia Anna; Bernardo, Letizia; Piro, Amalia; Beer, Sven; Björk, Mats; Gullström, Martin; Buapet, Pimchanok; Rasmusson, Lina M.; Felisberto, Paulo; Gobert, Sylvie; Runcie, John W.; Silva, João; Olivé, Irene; Costa, Monya M.; Barrote, Isabel; Santos, Rui

    2017-02-01

    Here we present the results of a multiple organizational level analysis conceived to identify acclimative/adaptive strategies exhibited by the seagrass Posidonia oceanica to the daily fluctuations in the light environment, at contrasting depths. We assessed changes in photophysiological parameters, leaf respiration, pigments, and protein and mRNA expression levels. The results show that the diel oscillations of P. oceanica photophysiological and respiratory responses were related to transcripts and proteins expression of the genes involved in those processes and that there was a response asynchrony between shallow and deep plants probably caused by the strong differences in the light environment. The photochemical pathway of energy use was more effective in shallow plants due to higher light availability, but these plants needed more investment in photoprotection and photorepair, requiring higher translation and protein synthesis than deep plants. The genetic differentiation between deep and shallow stands suggests the existence of locally adapted genotypes to contrasting light environments. The depth-specific diel rhythms of photosynthetic and respiratory processes, from molecular to physiological levels, must be considered in the management and conservation of these key coastal ecosystems.

  2. Response of key stress-related genes of the seagrass Posidonia oceanica in the vicinity of submarine volcanic vents

    Directory of Open Access Journals (Sweden)

    C. Lauritano

    2015-03-01

    Full Text Available Submarine volcanic vents are being used as natural laboratories to assess the effects of CO2 on marine organisms and communities, as this gas is the main component of emissions. Seagrasses should positively react to increased dissolved carbon, but in vicinity of volcanic vents there may be toxic substances, that can have indirect effects on seagrasses. Here we analysed the expression of 35 stress-related genes in the Mediterranean keystone seagrass species P. oceanica in the vicinity of submerged volcanic vents located in the Islands of Ischia and Panarea, Italy, and compared them with those from control sites away from the influence of vents. Reverse Transcription-Quantitative Polymerase Chain Reaction (RT-qPCR was used to characterize the expression levels of genes. Fifty one per cent of genes analysed showed significant expression changes. Metal detoxification genes were mostly down-regulated in relation to controls both in Ischia and Panarea locations, indicating that P. oceanica does not increase the synthesis of heavy metal detoxification proteins in response to the environmental conditions present at the two vents. The expression levels of genes involved in free radical detoxification indicate that, in contrast with Ischia, P. oceanica at the Panarea vent face stressors that result in the production of reactive oxygen species triggering antioxidant responses. In addition, heat shock proteins were also activated at Panarea and not at Ischia. Overall, our study reveals that P. oceanica is generally under higher stress in the vicinity of the vents at Panarea than at Ischia, possibly resulting from environmental and evolutionary differences existing between the two volcanic sites. This is the first study analysing gene responses in marine plants living near natural CO2 vents and our results call for a careful consideration of factors, other than CO2 and acidification, that can cause stress to seagrasses and other organisms near volcanic vents.

  3. Lack of Impact of Posidonia oceanica Leaf Nutrient Enrichment on Sarpa salpa Herbivory: Additional Evidence for the Generalist Consumer Behavior of This Cornerstone Mediterranean Herbivore.

    Science.gov (United States)

    Marco-Méndez, Candela; Wessel, Caitlin; Scheffel, Whitney; Ferrero-Vicente, Luis; Fernández-Torquemada, Yolanda; Cebrián, Just; Heck, Kenneth L; Sánchez-Lizaso, Jose Luis

    2016-01-01

    The fish Sarpa salpa (L.) is one of the main macroherbivores in the western Mediterranean. Through direct and indirect mechanisms, this herbivore can exert significant control on the structure and functional dynamics of seagrass beds and macroalgae. Past research has suggested nutritional quality of their diet influences S. salpa herbivory, with the fish feeding more intensively and exerting greater top down control on macrophytes with higher internal nutrient contents. However recent findings have questioned this notion and shown that herbivores do not preferentially feed on macrophytes with higher nutrient contents, but rather feed on a wide variety of them with no apparent selectivity. To contribute to this debate, we conducted a field fertilization experiment where we enriched leaves of the seagrass Posidonia oceanica, a staple diet for S. salpa, and examined the response by the herbivore. These responses included quantification of leaf consumption in fertilized and non-fertilized/control plots within the bed, and food choice assays where fertilized and non-fertilized/control leaves were simultaneously offered to the herbivore. Despite the duration of leaf exposure to herbivores (30 days) and abundant schools of S. salpa observed around the plots, leaf consumption was generally low in the plots examined. Consumption was not higher on fertilized than on non-fertilized leaves. Food choice experiments did not show strong evidence for selectivity of enriched leaves. These results add to a recent body of work reporting a broad generalist feeding behavior by S. salpa with no clear selectivity for seagrass with higher nutrient content. In concert, this and other studies suggest S. salpa is often generalist consumers not only dictated by diet nutrient content but by complex interactions between other traits of nutritional quality, habitat heterogeneity within their ample foraging area, and responses to predation risk.

  4. Response of key stress-related genes of the seagrass Posidonia oceanica in the vicinity of submarine volcanic vents

    Science.gov (United States)

    Lauritano, C.; Ruocco, M.; Dattolo, E.; Buia, M. C.; Silva, J.; Santos, R.; Olivé, I.; Costa, M. M.; Procaccini, G.

    2015-07-01

    Submarine volcanic vents are being used as natural laboratories to assess the effects of increased ocean acidity and carbon dioxide (CO2) concentration on marine organisms and communities. However, in the vicinity of volcanic vents other factors in addition to CO2, which is the main gaseous component of the emissions, may directly or indirectly confound the biota responses to high CO2. Here we used for the first time the expression of antioxidant and stress-related genes of the seagrass Posidonia oceanica to assess the stress levels of the species. Our hypothesis is that unknown factors are causing metabolic stress that may confound the putative effects attributed to CO2 enrichment only. We analyzed the expression of 35 antioxidant and stress-related genes of P. oceanica in the vicinity of submerged volcanic vents located in the islands of Ischia and Panarea, Italy, and compared them with those from control sites away from the influence of vents. Reverse-transcription quantitative polymerase chain reaction (RT-qPCR) was used to characterize gene expression patterns. Fifty-one percent of genes analyzed showed significant expression changes. Metal detoxification genes were mostly down-regulated in relation to controls at both Ischia and Panarea, indicating that P. oceanica does not increase the synthesis of heavy metal detoxification proteins in response to the environmental conditions present at the two vents. The up-regulation of genes involved in the free radical detoxification response (e.g., CAPX, SODCP and GR) indicates that, in contrast with Ischia, P. oceanica at the Panarea site faces stressors that result in the production of reactive oxygen species, triggering antioxidant responses. In addition, heat shock proteins were also activated at Panarea and not at Ischia. These proteins are activated to adjust stress-accumulated misfolded proteins and prevent their aggregation as a response to some stressors, not necessarily high temperature. This is the first

  5. Biokinetics of selected heavy metals and radionuclides in two marine macrophytes: the seagrass Posidonia oceanica and the alga Caulerpa taxifolia

    Energy Technology Data Exchange (ETDEWEB)

    Warnau, M. [Universite Libre de Bruxelles (Belgium). Lab. de Biologie Marine; Fowler, S.W.; Teyssie, J.-L. [International Atomic Energy Agency, Monaco (Monaco). Marine Environment Lab.

    1996-08-02

    Uptake and loss kinetics of Zn, Ag, Cd, {sup 134}Cs, and {sup 241}Am by shoots of the seagrass Posidonia oceanica and fronds of the green alga Caulerpa taxifolia were determined in controlled laboratory radiotracer experiments using low contaminant concentrations. The two species accumulated most of the elements efficiently. The only exceptions were {sup 134}Cs in both P. oceanica and C. taxifolia and Cd in C. taxifolia (concentration factors {<=} 6.4). Steady state in uptake was reached in C.taxifolia for each element except Ag. In P. oceanica, steady state was noted for the uptake of Ag and {sup 134}Cs whereas Zn, Cd, and {sup 241}Am were linearly accumulated during the course of the experiment (15 d). With respect to relative metal bioavailability, the different compartments of P. oceanica shoots were generally ranked in the order: leaf epiphytes > adult leaves intermediate leaves > leaf sheaths. The long-lived component of the loss kinetics for each element in P. oceanica was characterized by a relatively short biological half-life (T{sub b1/2} 28 d). However, observations for the individual compartments indicated that adult leaves had a high retention capacity for Ag and {sup 134}Cs, with virtually 100% retained after 21 d in uncontaminated sea water. In C. taxifolia, the long-lived component of the loss kinetics for each element was characterized by a T{sub b1/2} value that was not significantly different from infinity, an observation which suggests that a substantial fraction of the metal or radionuclide incorporated during a contamination event would be irreversibly bound by this algal species. (author).

  6. Epiphytes and nutrient contents influence Sarpa salpa herbivory on Caulerpa spp vs. seagrass species in Mediterranean meadows

    Science.gov (United States)

    Marco-Méndez, Candela; Ferrero-Vicente, Luis Miguel; Prado, Patricia; Sánchez-Lizaso, Jose Luis

    2017-01-01

    Mediterranean seagrass ecosystems are endangered by increased colonization of Caulerpa species, which may replace them, affecting key ecosystem processes. The fish Sarpa salpa (L.) is one of the main macroherbivores in the western Mediterranean seagrass meadows which is known to feed on a wide range of macroalgae such as Caulerpa species. In order to elucidate if this consumption could minimize the spread of invasive species, during summer-autumn 2012, we investigate the importance of S. salpa herbivory pressure on C. prolifera and C. cylindracea compared to Posidonia oceanica and Cymodocea nodosa in a mixed meadow. A combination of field experiments and dietary analyses were used to investigate consumption rates, dietary contributions, and feeding preferences for the different macrophytes, including the role of epiphytes and nutrient contents in mediating fish herbivory. In summer, C. nodosa was the most consumed macrophyte (12.75 ± 3.43 mg WW·d-1), probably influenced by higher fish densities, higher nutritional quality of leaves and epiphytes, and by differences in epiphyte composition. Feeding observations suggest that fish may have a variable diet, although with a consistent selection of mixed patches with C. nodosa and C. prolifera. Indeed, food choice experiments suggest that when seagrass leaves are not epiphytized, fish prefer feeding on C. prolifera. Gut content and stable isotopic analyses supported the dietary importance of epiphytes and C. prolifera but also suggested that C. cylindracea could occasionally be an important food item for S. salpa. Our results highlight the role of epiphytes in S. salpa feeding decisions but also suggest that C. nodosa and C. prolifera may have an important contribution to fish diet. The variability in S. salpa diet confirm the need to carry out multiple approach studies for a better understanding of its potential influence over different macrophytes species.

  7. Whole-system metabolism and CO2 fluxes in a Mediterranean Bay dominated by seagrass beds (Palma Bay, NW Mediterranean

    Directory of Open Access Journals (Sweden)

    F. Gazeau

    2005-01-01

    Full Text Available Planktonic and benthic incubations (bare and Posidonia oceanica vegetated sediments were performed at monthly intervals from March 2001 to October 2002 in a seagrass vegetated area of the Bay of Palma (Mallorca, Spain. Results showed a contrast between the planktonic compartment, which was on average near metabolic balance (−4.6±5.9 mmol O2 m-2 d-1 and the benthic compartment, which was autotrophic (17.6±8.5 mmol O2 m-2 d-1. During two cruises in March and June 2002, planktonic and benthic incubations were performed at several stations in the bay to estimate the whole-system metabolism and to examine its relationship with partial pressure of CO2 (pCO2 and apparent oxygen utilisation (AOU spatial patterns. Moreover, during the second cruise, when the residence time of water was long enough, net ecosystem production (NEP estimates based on incubations were compared, over the Posidonia oceanica meadow, to rates derived from dissolved inorganic carbon (DIC and oxygen (O2 mass balance budgets. These budgets provided NEP estimates in fair agreement with those derived from direct metabolic estimates based on incubated samples over the Posidonia oceanica meadow. Whereas the seagrass community was autotrophic, the excess organic carbon production therein could only balance the planktonic heterotrophy in shallow waters relative to the maximum depth of the bay (55 m. This generated a horizontal gradient from autotrophic or balanced communities in the shallow seagrass-covered areas, to strongly heterotrophic communities in deeper areas of the bay. It seems therefore that, on an annual scale in the whole bay, the organic matter production by the Posidonia oceanica may not be sufficient to fully compensate the heterotrophy of the planktonic compartment, which may require external organic carbon inputs, most likely from land.

  8. Development of an Efficient Protein Extraction Method Compatible with LC-MS/MS for Proteome Mapping in Two Australian Seagrasses Zostera muelleri and Posidonia australis

    Directory of Open Access Journals (Sweden)

    Zhijian Jiang

    2017-08-01

    Full Text Available The availability of the first complete genome sequence of the marine flowering plant Zostera marina (commonly known as seagrass in early 2016, is expected to significantly raise the impact of seagrass proteomics. Seagrasses are marine ecosystem engineers that are currently declining worldwide at an alarming rate due to both natural and anthropogenic disturbances. Seagrasses (especially species of the genus Zostera are compromised for proteomic studies primarily due to the lack of efficient protein extraction methods because of their recalcitrant cell wall which is rich in complex polysaccharides and a high abundance of secondary metabolites in their cells. In the present study, three protein extraction methods that are commonly used in plant proteomics i.e., phenol (P; trichloroacetic acid/acetone/SDS/phenol (TASP; and borax/polyvinyl-polypyrrolidone/phenol (BPP extraction, were evaluated quantitatively and qualitatively based on two dimensional isoelectric focusing (2D-IEF maps and LC-MS/MS analysis using the two most abundant Australian seagrass species, namely Zostera muelleri and Posidonia australis. All three tested methods produced high quality protein extracts with excellent 2D-IEF maps in P. australis. However, the BPP method produces better results in Z. muelleri compared to TASP and P. Therefore, we further modified the BPP method (M-BPP by homogenizing the tissue in a modified protein extraction buffer containing both ionic and non-ionic detergents (0.5% SDS; 1.5% Triton X-100, 2% PVPP and protease inhibitors. Further, the extracted proteins were solubilized in 0.5% of zwitterionic detergent (C7BzO instead of 4% CHAPS. This slight modification to the BPP method resulted in a higher protein yield, and good quality 2-DE maps with a higher number of protein spots in both the tested seagrasses. Further, the M-BPP method was successfully utilized in western-blot analysis of phosphoenolpyruvate carboxylase (PEPC—a key enzyme for carbon

  9. Whole-system metabolism and CO2 fluxes in a Mediterranean Bay dominated by seagrass beds (Palma Bay, NW Mediterranean

    Directory of Open Access Journals (Sweden)

    A. V. Borges

    2004-10-01

    Full Text Available The relationship between whole-system metabolism estimates based on planktonic and benthic incubations (bare sediments and seagrass, Posidonia oceanica meadows, and CO2 fluxes across the air-sea interface were examined in the Bay of Palma (Mallorca, Spain during two cruises in March and June 2002. Moreover, planktonic and benthic incubations were performed at monthly intervals from March 2001 to October 2002 in a seagrass vegetated area of the bay. From the annual study, results showed a contrast between the planktonic compartment, which was heterotrophic during most of the year, except for occasional bloom episodes, and the benthic compartment, which was slightly autotrophic. Whereas the seagrass community was autotrophic, the excess organic carbon production therein could only balance the excess respiration of the planktonic compartment in shallow waters (2 fields and fluxes across the bay observed during the two extensive cruises in 2002. Finally, dissolved inorganic carbon and oxygen budgets provided NEP estimates in fair agreement with those derived from direct metabolic estimates based on incubated samples over the Posidonia oceanica meadow.

  10. The role of meiofauna in the energy transfer in a Mediterranean seagrass bed (Calvi, Corsica)

    OpenAIRE

    Mascart, Thibaud

    2010-01-01

    Meiofaunal communities of five different habitats characterised by different qualities of macrophytodetritus were sampled in a Mediterranean seagrass bed. Two different kinds of meiofauna communities were distinguished amongst the five habitats. A benthic community of meiofauna living on a sediment substrate or in highly fragmented macrophytodetritus and a foliar, epiphytal community associated with seagrass leaves and low fragmented macrophytodetritus leaves. The diversity index amongst thes...

  11. Herbivory on the seagrass Cymodocea nodosa (Ucria) Ascherson in contrasting Spanish Mediterranean habitats

    NARCIS (Netherlands)

    Cebrian, J.; Duarte, C.M.; Marbà, N.

    1996-01-01

    We assess the magnitude and variability of herbivory (i.e. leaf consumption and sloughing caused by herbivore bites) on the seagrass Cymodocea nodosa along the Spanish Mediterranean coast and test the hypothesis that this is higher in meadows growing in sheltered bays than in exposed, open zones. To

  12. Response of the seagrass Posidonia oceanica to different light environments: Insights from a combined molecular and photo-physiological study.

    Science.gov (United States)

    Dattolo, E; Ruocco, M; Brunet, C; Lorenti, M; Lauritano, C; D'Esposito, D; De Luca, P; Sanges, R; Mazzuca, S; Procaccini, G

    2014-10-01

    Here we investigated mechanisms underlying the acclimation to light in the marine angiosperm Posidonia oceanica, along its bathymetric distribution (at -5 m and -25 m), combining molecular and photo-physiological approaches. Analyses were performed during two seasons, summer and autumn, in a meadow located in the Island of Ischia (Gulf of Naples, Italy), where a genetic distinction between plants growing above and below the summer thermocline was previously revealed. At molecular level, analyses carried out using cDNA-microarray and RT-qPCR, revealed the up-regulation of genes involved in photoacclimation (RuBisCO, ferredoxin, chlorophyll binding proteins), and photoprotection (antioxidant enzymes, xanthophyll-cycle related genes, tocopherol biosynthesis) in the upper stand of the meadow, indicating that shallow plants are under stressful light conditions. However, the lack of photo-damage, indicates the successful activation of defense mechanisms. This conclusion is also supported by several responses at physiological level as the lower antenna size, the higher number of reaction centers and the higher xanthophyll cycle pigment pool, which are common plant responses to high-light adaptation/acclimation. Deep plants, despite the lower available light, seem to be not light-limited, thanks to some shade-adaptation strategies (e.g. higher antenna size, lower Ek values). Furthermore, also at the molecular level there were no signs of stress response, indicating that, although the lower energy available, low-light environments are more favorable for P. oceanica growth. Globally, results of whole transcriptome analysis displayed two distinct gene expression signatures related to depth distribution, reflecting the different light-adaptation strategies adopted by P. oceanica along the depth gradient. This observation, also taking into account the genetic disjunction of clones along the bathymetry, might have important implications for micro-evolutionary processes

  13. Trace metal distributions in Posidonia oceanica and sediments from Taranto Gulf (Ionian Sea, Southern Italy

    Directory of Open Access Journals (Sweden)

    A. DI LEO

    2013-04-01

    Full Text Available Distribution of metals (Hg, Pb, Sn, Cu, Cd and Zn was determined in sediments and in different tissues of Posidonia oceanica collected from San Pietro Island, Taranto Gulf (Ionian Sea, Southern Italy. In seagrass, results, compared with metal concentrations in sediments, showed that the highest concentrations of Hg, Pb, Sn and Cu were found in the roots, while in the green leaves were found the highest levels of Cd and Zn. Instead the lowest metal concentrations were found in the basal part of the leaf. Levels of  metals in the leaves were similar to those found by other authors in uncontaminated areas of the Mediterranean Sea. Mercury levels in roots were correlated to levels in sediments. This could demonstrate the plant memorizes sediments contamination . This study reinforces the usefulness and the relevance of Posidonia oceanica as an indicator of spatial metal contamination and an interesting tool for environmental quality evaluation.

  14. Trace metal distributions in Posidonia oceanica and sediments from Taranto Gulf (Ionian Sea, Southern Italy

    Directory of Open Access Journals (Sweden)

    A. DI LEO

    2013-03-01

    Full Text Available Distribution of metals (Hg, Pb, Sn, Cu, Cd and Zn was determined in sediments and in different tissues of Posidonia oceanica collected from San Pietro Island, Taranto Gulf (Ionian Sea, Southern Italy. In seagrass, results, compared with metal concentrations in sediments, showed that the highest concentrations of Hg, Pb, Sn and Cu were found in the roots, while in the green leaves were found the highest levels of Cd and Zn. Instead the lowest metal concentrations were found in the basal part of the leaf. Levels of  metals in the leaves were similar to those found by other authors in uncontaminated areas of the Mediterranean Sea. Mercury levels in roots were correlated to levels in sediments. This could demonstrate the plant memorizes sediments contamination . This study reinforces the usefulness and the relevance of Posidonia oceanica as an indicator of spatial metal contamination and an interesting tool for environmental quality evaluation.

  15. Mapping of the Seagrass Cover Along the Mediterranean Coast of Turkey Using Landsat 8 Oli Images

    Science.gov (United States)

    Bakirman, T.; Gumusay, M. U.; Tuney, I.

    2016-06-01

    Benthic habitat is defined as ecological environment where marine animals, plants and other organisms live in. Benthic habitat mapping is defined as plotting the distribution and extent of habitats to create a map with complete coverage of the seabed showing distinct boundaries separating adjacent habitats or the use of spatially continuous environmental data sets to represent and predict biological patterns on the seafloor. Seagrass is an essential endemic marine species that prevents coast erosion and regulates carbon dioxide absorption in both undersea and atmosphere. Fishing, mining, pollution and other human activities cause serious damage to seabed ecosystems and reduce benthic biodiversity. According to the latest studies, only 5-10% of the seafloor is mapped, therefore it is not possible to manage resources effectively, protect ecologically important areas. In this study, it is aimed to map seagrass cover using Landsat 8 OLI images in the northern part of Mediterranean coast of Turkey. After pre-processing (e.g. radiometric, atmospheric, water depth correction) of Landsat images, coverage maps are produced with supervised classification using in-situ data which are underwater photos and videos. Result maps and accuracy assessment are presented and discussed.

  16. Population structure and secondary production of Siriella clausii, a dominant detritus feeding mysid in Posidonia oceanica meadows (W Mediterranean Sea)

    OpenAIRE

    Barberá Cebrián, Carmen; Sanchez-Jerez, Pablo; Sorbe, Jean Claude

    2013-01-01

    Temporal trends in abundance, demographic structure of the population and secondary production of Siriella clausii were studied at three different sectors of Posidonia oceanica meadows in the SE Iberian Peninsula, with different levels of habitat complexity. Secondary production was calculated through three methods widely employed in marine invertebrates: the Hynes method (based on demographic structure data) and models by Morin-Bourassa and Brey (based on biomass data). This filter/grazer an...

  17. Bathymetric variation of epiphytic assemblages on Posidonia oceanica (L.) Delile leaves in relation to anthropogenic disturbance in the southeastern Mediterranean.

    Science.gov (United States)

    Ben Brahim, Mounir; Mabrouk, Lotfi; Hamza, Asma; Mahfoudi, Mabrouka; Bouain, Abderrahmane; Aleya, Lotfi

    2014-12-01

    A survey of the epiphytic leaves of Posidonia oceanica was conducted along a depth transect at both the control station Attaya in the Kerkennah Islands and the disturbed Mahres station on the Sfax coast (Tunisia). Samples were collected by scuba divers at depths of 5, 10, 15, and 20 m in July 2008. We evaluated whether the pattern of spatial variability of the macroepiphyte assemblages of leaves of Posidonia oceanica differed in relation to anthropogenic interference. The results indicate that the decrease in shoot density and leaf length according to depth was low at Mahres. The biomass of epiphytic leaves and the percentage cover of epiphytic assemblages decreased with depth for both stations and heavily at Mahres, this decline being related to anthropogenic disturbance. This study shows that the highest values of epifauna and epiflora were detected at the disturbed station Mahres. Macroalgae assemblages decreased with depth at both stations and were dominated by Rhodophyta, whereas the percentage cover of the epifauna leaf that decreases according to depth was dominated by Hydrozoa and Bryozoa. Changes in epiphyte assemblages, epiphytic biomass, percentage cover, and species richness in proportion to Heterokontophyta, Rhodophyta, Cyanobacteria, Hydrozoa, Porifera, and Tunicata between the two stations constitute promising tools for detecting environmental disturbance.

  18. Future heat waves due to climate change threaten the survival of Posidonia oceanica seedlings.

    Science.gov (United States)

    Guerrero-Meseguer, Laura; Marín, Arnaldo; Sanz-Lázaro, Carlos

    2017-11-01

    Extreme weather events are major drivers of ecological change, and their occurrence is likely to increase due to climate change. The transient increases in atmospheric temperatures are leading to a greater occurrence of heat waves, extreme events that can produce a substantial warming of water, especially in enclosed basins such as the Mediterranean Sea. Here, we tested the effects of current and predicted heat waves on the early stages of development of the seagrass Posidonia oceanica. Temperatures above 27 °C limited the growth of the plant by inhibiting its photosynthetic system. It suffered a reduction in leaf growth and faster leaf senescence, and in some cases mortality. This study demonstrates that the greater frequency of heat waves, along with anticipated temperature rises in coming decades, are expected to negatively affect the germination of P. oceanica seedlings. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Sustainable Management of Seagrass Meadows: the GEOSS AIP-6 Pilot

    Science.gov (United States)

    Santoro, Mattia; Pastres, Roberto; Zucchetta, Matteo; Venier, Chiara; Roncella, Roberto; Bigagli, Lorenzo; Mangin, Antoine; Amine Taji, Mohamed; Gonzalo Malvarez, Gonzalo; Nativi, Stefano

    2014-05-01

    Seagrass meadows (marine angiosperm plants) occupy less than 0.2% of the global ocean surface, annually store about 10-18% of the so-called "Blue Carbon", i.e. the Carbon stored in coastal vegetated areas. Recent literature estimates that the flux to the long-term carbon sink in seagrasses represents 10-20% of seagrasses global average production. Such figures can be translated into economic benefits, taking into account that a ton of carbon dioxide in Europe is paid at around 15 € in the carbon market. This means that the organic carbon retained in seagrass sediments in the Mediterranean is worth 138 - 1128 billion €, which represents 6-23 € per square meter. This is 9-35 times more than one square meter of tropical forest soil (0.66 € per square meter), or 5-17 times when considering both the above and the belowground compartments in tropical forests. According the most conservative estimations, about 10% of the Mediterranean meadows have been lost during the last century. To estimate seagrass meadows distribution, a Species Distribution Model (SDM) can be used. SDM is a tool that is used to evaluate the potential distribution of a given species (e.g. Posidonia oceanica for seagrass) on the basis of the features (bio-chemical-physical parameters) of the studied environment. In the framework of the GEOSS (Global Earth Observation System of Systems) initiative, the FP7 project MEDINA developed a showcase as part of the GEOSS Architecture Interoperability Pilot - phase 6 (AIP-6). The showcase aims at providing a tool for the sustainable management of seagrass meadows along the Mediterranean coastline by integrating the SDM with available GEOSS resources. This way, the required input data can be searched, accessed and ingested into the model leveraging the brokering framework of the GEOSS Common Infrastructure (GCI). This framework is comprised of a set of middle-ware components (Brokers) that are in charge of implementing the needed interoperability

  20. A Bayesian spatial approach for predicting seagrass occurrence

    Science.gov (United States)

    March, D.; Alós, J.; Cabanellas-Reboredo, M.; Infantes, E.; Jordi, A.; Palmer, M.

    2013-10-01

    We implement a Bayesian spatial approach to predict and map the probability of occurrence of seagrass Posidonia oceanica at high spatial resolution based environmental variables. We found that depth, near-bottom orbital velocities and a spectral pattern of Landsat imagery were relevant environmental variables, although there was no effect of slope or water residence time. We generated a data inventory of P. oceanica samples at Palma Bay, NW Mediterranean, from three main sources: side scan sonar, aerial imagery and a customized drop-camera system. A hierarchical Bayesian spatial model for non-Gaussian data was used to relate presence-absence data of P. oceanica with environmental variables in the presence of spatial autocorrelation (SA). A spatial dimension reduction method, the predictive process approach, was implemented to overcome computational constraints for moderately large datasets. Our results suggest that incorporating spatial random effects removes SA from the residuals and improves model fit compared to non-spatial regression models. The main products of this work were probability and uncertainty model maps, which could benefit seagrass management and the assessment of the ecological status of seagrass meadows.

  1. Morphology and composition of beach-cast Posidonia oceanica litter on beaches with different exposures

    Science.gov (United States)

    Simeone, Simone; De Falco, Giovanni

    2012-05-01

    Posidonia oceanica seagrass litter is commonly found along sandy shores in the Mediterranean region, forming structures called banquettes, which are often removed in order to allow the beach to be used for tourism. This paper evaluates the relationship between the morphology and composition of banquettes and beach exposure to dominant waves. A Real Time Kinematic Differential Global Positioning System was used to evaluate the variability of banquettes and beach morphology over a period of 1 year. Banquette samples, collected at two different levels of the beach profile (i.e. foreshore and backshore), were used to evaluate the contribution of leaves, rhizomes and sediments to the total weight. Banquettes showed a higher volume, thickness and cross-shore length on exposed beaches, whereas narrower litter deposits were found on the sheltered beach. On exposed beaches, banquettes were deposited in beach zones characterized by changes in elevation. These changes in elevation were mainly due to the deposition and erosion of sediments and secondly to the deposition and or erosion of leaf litter. On sheltered beaches, the variability in beach morphology was low and was restricted to areas where the banquettes were located. The leaf/sediment ratio changed along the cross-shore profile. On the backshore, banquettes were a mixture of sediments and leaves, whereas leaves were the main component on the foreshore, independently of the beach exposure. The processes which control the morphodynamics in the swash zone could explain the variability of banquette composition along the cross-shore profile. Finally, this study highlighted that Posidonia oceanica seagrass litter plays an important role in the geomorphology of the beachface and its removal can have a harmful impact on the beaches.

  2. Effects of Posidonia oceanica beach-cast on germination, growth and nutrient uptake of coastal dune plants.

    Directory of Open Access Journals (Sweden)

    Silvia Del Vecchio

    Full Text Available Seagrass meadows play an important role in marine ecosystems. A part of seagrass production is also exported to adjacent coastal terrestrial systems, possibly influencing their functioning. In this work we experimentally analyzed the effect of Posidonia oceanica beach-cast on plant germination, growth, and nutrient uptake of two plant species (Cakile maritima and Elymus farctus that grow on upper beaches and fore dunes along the Mediterranean coasts. We compared plants growing in simple sand (control with those growing in a substrate enriched with P. oceanica wrack (treatment in laboratory. P. oceanica wrack doubled the N substrate pool and kept the substrate humid. Plants growing in the treated substrate grew faster, were twice as large as those growing in the control substrate, while tissues were enriched in N and P (Cakile by the 1.3 fold in N and 2.5 fold in P; Elymus by 1.5 fold in N and 2 fold in P. Our results suggest a positive effect of seagrass litter for the enhancing of dune species, highlighting its role for the conservation of coastal dune ecosystems.

  3. Effects of Posidonia oceanica beach-cast on germination, growth and nutrient uptake of coastal dune plants.

    Science.gov (United States)

    Del Vecchio, Silvia; Marbà, Núria; Acosta, Alicia; Vignolo, Clara; Traveset, Anna

    2013-01-01

    Seagrass meadows play an important role in marine ecosystems. A part of seagrass production is also exported to adjacent coastal terrestrial systems, possibly influencing their functioning. In this work we experimentally analyzed the effect of Posidonia oceanica beach-cast on plant germination, growth, and nutrient uptake of two plant species (Cakile maritima and Elymus farctus) that grow on upper beaches and fore dunes along the Mediterranean coasts. We compared plants growing in simple sand (control) with those growing in a substrate enriched with P. oceanica wrack (treatment) in laboratory. P. oceanica wrack doubled the N substrate pool and kept the substrate humid. Plants growing in the treated substrate grew faster, were twice as large as those growing in the control substrate, while tissues were enriched in N and P (Cakile by the 1.3 fold in N and 2.5 fold in P; Elymus by 1.5 fold in N and 2 fold in P). Our results suggest a positive effect of seagrass litter for the enhancing of dune species, highlighting its role for the conservation of coastal dune ecosystems.

  4. Altered epiphyte community and sea urchin diet in Posidonia oceanica meadows in the vicinity of volcanic CO2 vents.

    Science.gov (United States)

    Nogueira, Patricia; Gambi, Maria Cristina; Vizzini, Salvatrice; Califano, Gianmaria; Tavares, Ana Mafalda; Santos, Rui; Martínez-Crego, Begoña

    2017-06-01

    Ocean acidification (OA) predicted for 2100 is expected to shift seagrass epiphyte communities towards the dominance of more tolerant non-calcifying taxa. However, little is known about the indirect effects of such changes on food provision to key seagrass consumers. We found that epiphyte communities of the seagrass Posidonia oceanica in two naturally acidified sites (i.e. north and south sides of a volcanic CO2 vent) and in a control site away from the vent at the Ischia Island (NW Mediterranean Sea) significantly differed in composition and abundance. Such differences involved a higher abundance of non-calcareous crustose brown algae and a decline of calcifying polychaetes in both acidified sites. A lower epiphytic abundance of crustose coralline algae occurred only in the south side of the vents, thus suggesting that OA may alter epiphyte assemblages in different ways due to interaction with local factors such as differential fish herbivory or hydrodynamics. The OA effects on food items (seagrass, epiphytes, and algae) indirectly propagated into food provision to the sea urchin Paracentrotus lividus, as reflected by a reduced P. oceanica exploitation (i.e. less seagrass and calcareous epiphytes in the diet) in favour of non-calcareous green algae in both vent sites. In contrast, we detected no difference close and outside the vents neither in the composition of sea urchin diet nor in the total abundance of calcareous versus non-calcareous taxa. More research, under realistic scenarios of predicted pH reduction (i.e. ≤ 0.32 units of pH by 2100), is still necessary to better understand cascading effects of this altered urchin exploitation of food resources under acidified conditions on ecosystem diversity and function. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Human impact, geomorphological and bio-environmental indicators for mapping and monitoring of a Mediterranean urban-beach with Posidonia oceanica (Gulf of Cagliari-Sardinia)

    Science.gov (United States)

    De Muro, Sandro; Pusceddu, Nicola; Frongia, Paolo; Buosi, Carla; Passarella, Marinella; Ibba, Angelo

    2016-04-01

    This work describes the human conditioned evolution (medium term) and the short term dynamics (mainly sediment transport) in southern Sardinia beach (between Giorgino and Cala d'Orri, about 11km), composed of fine to coarse quartz sand, backed by dune ridges and lagoons. The study was founded by NEPTUNE Project, Tender6 (L n. 7/2007). Geomorphological and bio-environmental indicators as: urbanization and coastal defence expansion, dune and beach changes, biotic indices (benthic foraminifera and Posidonia meadow) have been used. Medium-term evolution, over a period of 60 years, was carried out by ortho-images (1954-2015) for reconstructing coastline changes at this temporal scale. The main modifications were the building of the canal harbor, the consequent loss of 2.5km of beach, and the construction of several coastal defense structures, which caused asymmetric accumulations (lee zones) and erosion areas. Short-term variations have been periodically monitored (2014-2015) during 5 different field surveys (DGPS and Echo-sounder data) obtaining topo-bathymetric digital models. Sedimentary and hydrodynamic characteristics have been studied. Wave propagation, coastal currents and sediment transport, have been simulated through numerical models within Delft3D software. The results obtained allowed to visualize the response of the beach to wave stress, forced from SW, S, SE (Cagliari buoy and weather data). The comparison between data collected, thematic maps and models allowed to identify the main controlling factors and distribution mechanisms of the sedimentary paths on the shoreface. Those human modifications (e.g. building of the canal harbour and jetties, lagoon mouths stabilization, the consequent modified hydrodynamics and bottom trawling) have direct influence on the Posidonia oceanica and on its upper limit. In 2002, the Italian Environment Office reported a wide area (between -4m and -20m) of degraded Posidonia and dead matte in front of the study beach

  6. Variability in the carbon storage of seagrass habitats and its implications for global estimates of blue carbon ecosystem service.

    Directory of Open Access Journals (Sweden)

    Paul S Lavery

    Full Text Available The recent focus on carbon trading has intensified interest in 'Blue Carbon'-carbon sequestered by coastal vegetated ecosystems, particularly seagrasses. Most information on seagrass carbon storage is derived from studies of a single species, Posidonia oceanica, from the Mediterranean Sea. We surveyed 17 Australian seagrass habitats to assess the variability in their sedimentary organic carbon (C org stocks. The habitats encompassed 10 species, in mono-specific or mixed meadows, depositional to exposed habitats and temperate to tropical habitats. There was an 18-fold difference in the Corg stock (1.09-20.14 mg C org cm(-3 for a temperate Posidonia sinuosa and a temperate, estuarine P. australis meadow, respectively. Integrated over the top 25 cm of sediment, this equated to an areal stock of 262-4833 g C org m(-2. For some species, there was an effect of water depth on the C org stocks, with greater stocks in deeper sites; no differences were found among sub-tidal and inter-tidal habitats. The estimated carbon storage in Australian seagrass ecosystems, taking into account inter-habitat variability, was 155 Mt. At a 2014-15 fixed carbon price of A$25.40 t(-1 and an estimated market price of $35 t(-1 in 2020, the C org stock in the top 25 cm of seagrass habitats has a potential value of $AUD 3.9-5.4 bill. The estimates of annual C org accumulation by Australian seagrasses ranged from 0.093 to 6.15 Mt, with a most probable estimate of 0.93 Mt y(-1 (10.1 t. km(-2 y(-1. These estimates, while large, were one-third of those that would be calculated if inter-habitat variability in carbon stocks were not taken into account. We conclude that there is an urgent need for more information on the variability in seagrass carbon stock and accumulation rates, and the factors driving this variability, in order to improve global estimates of seagrass Blue Carbon storage.

  7. Variability in the carbon storage of seagrass habitats and its implications for global estimates of blue carbon ecosystem service.

    Science.gov (United States)

    Lavery, Paul S; Mateo, Miguel-Ángel; Serrano, Oscar; Rozaimi, Mohammad

    2013-01-01

    The recent focus on carbon trading has intensified interest in 'Blue Carbon'-carbon sequestered by coastal vegetated ecosystems, particularly seagrasses. Most information on seagrass carbon storage is derived from studies of a single species, Posidonia oceanica, from the Mediterranean Sea. We surveyed 17 Australian seagrass habitats to assess the variability in their sedimentary organic carbon (C org) stocks. The habitats encompassed 10 species, in mono-specific or mixed meadows, depositional to exposed habitats and temperate to tropical habitats. There was an 18-fold difference in the Corg stock (1.09-20.14 mg C org cm(-3) for a temperate Posidonia sinuosa and a temperate, estuarine P. australis meadow, respectively). Integrated over the top 25 cm of sediment, this equated to an areal stock of 262-4833 g C org m(-2). For some species, there was an effect of water depth on the C org stocks, with greater stocks in deeper sites; no differences were found among sub-tidal and inter-tidal habitats. The estimated carbon storage in Australian seagrass ecosystems, taking into account inter-habitat variability, was 155 Mt. At a 2014-15 fixed carbon price of A$25.40 t(-1) and an estimated market price of $35 t(-1) in 2020, the C org stock in the top 25 cm of seagrass habitats has a potential value of $AUD 3.9-5.4 bill. The estimates of annual C org accumulation by Australian seagrasses ranged from 0.093 to 6.15 Mt, with a most probable estimate of 0.93 Mt y(-1) (10.1 t. km(-2) y(-1)). These estimates, while large, were one-third of those that would be calculated if inter-habitat variability in carbon stocks were not taken into account. We conclude that there is an urgent need for more information on the variability in seagrass carbon stock and accumulation rates, and the factors driving this variability, in order to improve global estimates of seagrass Blue Carbon storage.

  8. Dynamics of carbon sources supporting burial in seagrass sediments under increasing anthropogenic pressure

    KAUST Repository

    Mazarrasa, Inés

    2017-03-15

    Seagrass meadows are strong coastal carbon sinks of autochthonous and allochthonous carbon. The aim of this study was to assess the effect of coastal anthropogenic pressure on the variability of carbon sources in seagrass carbon sinks during the last 150 yr. We did so by examining the composition of the sediment organic carbon (Corg) stocks by measuring the δ13Corg signature and C : N ratio in 210Pb dated sediments of 11 Posidonia oceanica seagrass meadows around the Balearic Islands (Spain, Western Mediterranean) under different levels of human pressure. On average, the top meter sediment carbon deposits were mainly (59% ± 12%) composed by P. oceanica derived carbon whereas seston contribution was generally lower (41% ± 8%). The contribution of P. oceanica to the total sediment carbon stock was the highest (∼ 80%) in the most pristine sites whereas the sestonic contribution was the highest (∼ 40–80%) in the meadows located in areas under moderate to very high human pressure. Furthermore, an increase in the contribution of sestonic carbon and a decrease in that of seagrass derived carbon toward present was observed in most of the meadows examined, coincident with the onset of the tourism industry development and coastal urbanization in the region. Our results demonstrate a general increase of total carbon accumulation rate in P. oceanica sediments during the last century, mainly driven by the increase in sestonic Corg carbon burial, which may have important implications in the long-term carbon sink capacity of the seagrass meadows in the region examined.

  9. Residence time and Posidonia oceanica in Cabrera Archipelago National Park, Spain

    Science.gov (United States)

    Orfila, A.; Jordi, A.; Basterretxea, G.; Vizoso, G.; Marbà, N.; Duarte, C. M.; Werner, F. E.; Tintoré, J.

    2005-07-01

    Flushing time and residence time are studied in a small inlet in Cabrera National Park, Western Mediterranean Sea. Flushing time is studied using ADCP in situ data. Observed flushing time data are compared with the simulations from a three-dimensional coastal ocean numerical model. Residence time is assessed using virtual lagrangian particles and studying the number remaining within the analyzed domain. Results show a good agreement between observations and modeling estimations of the flushing time (i.e. 6 days from the ADCP data and 5.6 days from the numerical model). Residence time estimations yield a broad range of values, from 1 h in the Bay to over 30 days depending also on the horizontal and vertical position where particles were released. A continuous stirred tank reactor (CSTR) model for the Port yields a value of 8.7 days. Results obtained for the residence time appear to have a determinant impact over the meadows of the seagrass Posidonia oceanica, present inside the Port. Recirculation patterns and complex flows in coastal environments create a non-uniform distribution of the areas of accumulation of non-conservative properties that indicate that residence time concept is the correct approach when studying the impact of water transport over biological communities.

  10. Diversity, distribution and conservation of Chinese seagrass species

    Directory of Open Access Journals (Sweden)

    Fengying Zheng

    2013-09-01

    Full Text Available Seagrass beds are one of the most productive ecosystems on Earth and an important source of ecosystem services. Accurate mapping of spatial patterns of seagrass species diversity are lacking at the national scale in China, while taxonomic information on Chinese seagrass species requires an urgent update. This lack of information hinders national conservation and restoration programs for seagrass biodiversity. In this article we review studies of diversity, distributions and degradation of seagrass in China. A total of 22 seagrass species distributed along China’s coastal regions belong to ten genera and four families, and account for about 30% of known seagrass species worldwide. A check of herbarium material stored in Sun Yat-sen University showed that the seagrass species previously identified as Posidonia australis in Hainan is in fact Enhalus acoroides. From our analyses, two Chinese seagrass biotas are proposed. These include the South China Sea Bioregion (SCSBR and China’s Yellow Sea and Bohai Sea Bioregion (CYSBSBR. The SCSBR includes Hainan, Guangxi, Guangdong, Hongkong, Taiwan and Fujian provinces, and contains 15 seagrass species representing nine genera with Halophila ovalis being most widely distributed. The CYSBSBR includes Shandong, Hebei, Tianjin and Liaonin provinces and contains nine seagrass species belonging to three genera with Zostera marina being most widely distributed. The total distribution area for China’s seagrass meadows is estimated to be 8,765.1 ha, with Hainan, Guangdong and Guangxi provinces accounting for 64%, 11% and 10% of the area, respectively. Both the number and area of seagrass meadows are much higher in the SCSBR than in the CYSBSBR. In the SCSBR, seagrass meadows are mainly located in the eastern Hainan coast, Zhanjiang in Guangdong, Beihai in Guangxi and Dongsha Island in Taiwan, whereas in the CYSBSBR they predominate in Rongcheng in Shandong and Changhai in Liaoning. Halophila ovalis, Thalassia

  11. Mapping Spatial Patterns of Posidonia oceanica Meadows by Means of Daedalus ATM Airborne Sensor in the Coastal Area of Civitavecchia (Central Tyrrhenian Sea, Italy

    Directory of Open Access Journals (Sweden)

    Marco Marcelli

    2013-10-01

    Full Text Available The spatial distribution of sea bed covers and seagrass in coastal waters is of key importance in monitoring and managing Mediterranean shallow water environments often subject to both increasing anthropogenic impacts and climate change effects. In this context we present a methodology for effective monitoring and mapping of Posidonia oceanica (PO meadows in turbid waters using remote sensing techniques tested by means of LAI (Leaf Area Index point sea truth measurements. Preliminary results using Daedalus airborne sensor are reported referring to the PO meadows at Civitavecchia site (central Tyrrhenian sea where vessel traffic due to presence of important harbors and huge power plant represent strong impact factors. This coastal area, 100 km far from Rome (Central Italy, is characterized also by significant hydrodynamic variations and other anthropogenic factors that affect the health of seagrass meadows with frequent turbidity and suspended sediments in the water column. During 2011–2012 years point measurements of several parameters related to PO meadows phenology were acquired on various stations distributed along 20 km of coast between the Civitavecchia and S. Marinella sites. The Daedalus airborne sensor multispectral data were preprocessed with the support of satellite (MERIS derived water quality parameters to obtain here improved thematic maps of the local PO distribution. Their thematic accuracy was then evaluated as agreement (R2 with the point sea truth measurements and regressive modeling using an on purpose developd method.

  12. Epiphytes modulate Posidonia oceanica photosynthetic production, energetic balance, antioxidant mechanisms and oxidative damage

    OpenAIRE

    Monya Mendes Costa; Isabel eBarrote; João eSilva; Irene eOlivé; Ana eAlexandre; Sílvia eAlbano; Rui Orlando Pimenta Santos

    2015-01-01

    Epiphytes impose physical barriers to light penetration into seagrass leaves causing shading, which may decrease the production of oxygen reactive species (ROS), but also constitute a physical aggression that may trigger the production of ROS, leading to oxidative damage. Here we investigate the effects of epiphytes on Posidonia oceanica under both interactive perspectives, light attenuation and oxidative stress. Specifically the role of epiphytes in net photosynthesis, chlorophyll a and b, p...

  13. Epiphytes Modulate Posidonia oceanica Photosynthetic Production, Energetic Balance, Antioxidant Mechanisms, and Oxidative Damage

    OpenAIRE

    Monya M. Costa; Barrote, Isabel; SILVA, João; Olivé, Irene; Alexandre, Ana; Albano, Sílvia; Santos, Rui

    2015-01-01

    Epiphytes impose physical barriers to light penetration into seagrass leaves causing shading, which may decrease the production of reactive oxygen species (ROS), but also constitute a physical aggression that may trigger the production of ROS, leading to oxidative damage. Here we investigate the effects of epiphytes on Posidonia oceanica under both interactive perspectives, light attenuation and oxidative stress. Specifically the role of epiphytes in net photosynthesis, chlorophyll a and b, p...

  14. Modelling reference conditions for the upper limit of Posidonia oceanica meadows: a morphodynamic approach

    Science.gov (United States)

    Vacchi, Matteo; Misson, Gloria; Montefalcone, Monica; Archetti, Renata; Nike Bianchi, Carlo; Ferrari, Marco

    2014-05-01

    The upper portion of the meadows of the protected Mediterranean seagrass Posidonia oceanica occurs in the region of the seafloor mostly affected by surf-related effects. Evaluation of its status is part of monitoring programs, but proper conclusions are difficult to draw due to the lack of definite reference conditions. Comparing the position of the meadow upper limit with the beach morphodynamics (i.e. the distinctive type of beach produced by topography and wave climate) provided evidence that the natural landwards extension of meadows can be predicted. Here we present an innovative predictive cartographic approach able to identify the seafloor portion where the meadow upper limit should naturally lies (i.e. its reference conditions). The conceptual framework of this model is based on 3 essential components: i) Definition of the breaking depth geometry: the breaking limit represents the major constrain for the landward meadow development. We modelled the breaking limit (1 year return time) using the software Mike 21 sw. ii) Definition of the morphodynamic domain of the beach using the surf scaling index ɛ; iii) Definition of the P. oceanica upper limit geometry. We coupled detailed aerial photo with thematic bionomic cartography. In GIS environment, we modelled the seafloor extent where the meadow should naturally lies according to the breaking limit position and the morphodynamic domain of the beach. Then, we added the GIS layer with the meadow upper limit geometry. Therefore, the final output shows, on the same map, both the reference condition and the actual location of the upper limit. It make possible to assess the status of the landward extent of a given P. oceanica meadow and quantify any suspected or observed regression caused by anthropic factors. The model was elaborated and validated along the Ligurian coastline (NW Mediteraanean) and was positively tested in other Mediterranean areas.

  15. Assessment and physiological state of the Posidonia oceanica meadows in Porto Cristo (Manacor, Spain)

    Science.gov (United States)

    Sureda, Antoni; Box, Antonio; Tejada, Silvia

    2015-12-01

    In the Mediterranean Sea, Posidonia oceanica is the main seagrass meadow that brings food and shelter to many species. The P. oceanica deterioration is an indicator of its own status, since it is sensitive to many disturbances, such as human impacts or alien species. Lately, oxidative stress has been pointed out as another possible biomarker of the animal and plant status. The aim of this work was to evaluate the physiological status of the P. oceanica meadows in the Porto Cristo bay (Manacor, Mallorca, Balearic Islands, Western Mediterranean), evaluating the possible impact induced by human activity performed in the area. In situ measurements were quantified (shoot density, and the maximum length and width of P. oceanica leaves) by scuba divers. Leaf samples were collected to determine the catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities. The malondialdehyde (MDA) level as marker of lipid peroxidation was also evaluated. Shoot density, and length and width measurements of the leaves in the inner locations of the bay showed inferior structural features than the leaves from the outer areas. CAT, SOD and GPx enzymatic activities and lipid peroxidation were higher in leaves from the internal zones than in the outer placements. In conclusion, the general status of the of P. oceanica meadows on the Porto Cristo Bay according to structural and oxidative biomarkers evidenced a good physiological condition, although the areas nearest to the harbour and the beach reflect signs of human affection. Altogether, it reflects a good physiological condition of the meadows in the external areas of the Porto Cristo Bay.

  16. Use of a seagrass residency index to apportion commercial fishery landing values and recreation fisheries expenditure to seagrass habitat service.

    Science.gov (United States)

    Jackson, Emma L; Rees, Siân E; Wilding, Catherine; Attrill, Martin J

    2015-06-01

    Where they dominate coastlines, seagrass beds are thought to have a fundamental role in maintaining populations of exploited species. Thus, Mediterranean seagrass beds are afforded protection, yet no attempt to determine the contribution of these areas to both commercial fisheries landings and recreational fisheries expenditure has been made. There is evidence that seagrass extent continues to decline, but there is little understanding of the potential impacts of this decline. We used a seagrass residency index, that was trait and evidence based, to estimate the proportion of Mediterranean commercial fishery landings values and recreation fisheries total expenditure that can be attributed to seagrass during different life stages. The index was calculated as a weighted sum of the averages of the estimated residence time in seagrass (compared with other habitats) at each life stage of the fishery species found in seagrass. Seagrass-associated species were estimated to contribute 30%-40% to the value of commercial fisheries landings and approximately 29% to recreational fisheries expenditure. These species predominantly rely on seagrass to survive juvenile stages. Seagrass beds had an estimated direct annual contribution during residency of €58-91 million (4% of commercial landing values) and €112 million (6% of recreation expenditure) to commercial and recreational fisheries, respectively, despite covering seagrass degradation associated with ineffective management of seagrass beds and that policy to manage both fisheries and seagrass beds should take into account the socioeconomic implications of seagrass loss to recreational and commercial fisheries.

  17. Hydrophilic extract from Posidonia oceanica inhibits activity and expression of gelatinases and prevents HT1080 human fibrosarcoma cell line invasion.

    Science.gov (United States)

    Barletta, Emanuela; Ramazzotti, Matteo; Fratianni, Florinda; Pessani, Daniela; Degl'Innocenti, Donatella

    2015-01-01

    Posidonia oceanica (L.) Delile is an endemic Mediterranean sea-grass distributed in the infralittoral zones, where it forms meadows playing a recognized ecological role in the coastal marine habitat. Although its use as a traditional herbal remedy is poorly documented, recent literature reports interesting pharmacological activities as antidiabetic, antioxidant and vasoprotective. Differently from previous literature, this study presents a hydrophilic extraction method that recovers metabolites that may be tested in biological buffers. We showed for the first time in the highly invasive HT1080 human fibrosarcoma cell line that our hydrophilic extract from P. oceanica was able to strongly decrease gene and protein expression of gelatinases MMP-2 and MMP-9 and to directly inhibit in a dose-dependent manner gelatinolytic activity in vitro. Moreover, we have revealed that our extract strongly inhibited HT1080 cell migration and invasion. Biochemical analysis of the hydrophilic extract showed that catechins were the major constituents with minor contribution of gallic acid, ferulic acid and chlorogenic plus a fraction of uncharacterized phenols. However, if each individual compound was tested independently, none by itself was able to induce a direct inhibition of gelatinases as strong as that observed in total extract, opening up new routes to the identification of novel compounds. These results indicate that our hydrophilic extract from P. oceanica might be a source of new pharmacological natural products for treatment or prevention of several diseases related to an altered MMP-2 and MMP-9 expression.

  18. Trace element storage capacity of sediments in dead Posidonia oceanica mat from a chronically contaminated marine ecosystem.

    Science.gov (United States)

    Di Leonardo, Rossella; Mazzola, Antonio; Cundy, Andrew B; Tramati, Cecilia Doriana; Vizzini, Salvatrice

    2017-01-01

    Posidonia oceanica mat is considered a long-term bioindicator of contamination. Storage and sequestration of trace elements and organic carbon (Corg ) were assessed in dead P. oceanica mat and bare sediments from a highly polluted coastal marine area (Augusta Bay, central Mediterranean). Sediment elemental composition and sources of organic matter have been altered since the 1950s. Dead P. oceanica mat displayed a greater ability to bury and store trace elements and Corg than nearby bare sediments, acting as a long-term contaminant sink over the past 120 yr. Trace elements, probably associated with the mineral fraction, were stabilized and trapped despite die-off of the overlying P. oceanica meadow. Mat deposits registered historic contamination phases well, confirming their role as natural archives for recording trace element trends in marine coastal environments. This sediment typology is enriched with seagrass-derived refractory organic matter, which acts mainly as a diluent of trace elements. Bare sediments showed evidence of inwash of contaminated sediments via reworking; more rapid and irregular sediment accumulation; and, because of the high proportions of labile organic matter, a greater capacity to store trace elements. Through different processes, both sediment typologies represent a repository for chemicals and may pose a risk to the marine ecosystem as a secondary source of contaminants in the case of sediment dredging or erosion. Environ Toxicol Chem 2017;36:49-58. © 2016 SETAC. © 2016 SETAC.

  19. Retention of lignin in seagrasses: angiosperms that returned to the sea

    NARCIS (Netherlands)

    Klap, V.A.; Hemminga, M.A.; Boon, J.J.

    2000-01-01

    Using Curie-point Pyrolysis Gas Chromatography Mass Spectrometry (Py-GCMS) and Direct Temperature-resolved Mass Spectrometry (DT-MS), lignin was detected in highly purified preparations (Milled Wood Lignin = MWL) of various tissues of the seagrasses Zostera marina and Posidonia oceanica. The results

  20. Nutrient resorption from seagrass leaves

    NARCIS (Netherlands)

    Stapel, J.; Hemminga, M.A.

    1997-01-01

    The resorption of nutrients (C, N and P) from senescent leaves of six seagrass species from nine different locations in tropical (Indonesia and Kenya), Mediterranean (Spain) and temperate (The Netherlands) regions has been investigated. Resorption was quantitatively assessed by calculating the diffe

  1. Potential roles of Labyrinthula spp. in global seagrass population declines

    Digital Repository Service at National Institute of Oceanography (India)

    Sullivan, B.K.; Sherman, T.D.; Damare, V.S.; Lilje, O.; Gleason, F.H.

    ) isolated Labyrinthula spp. from lesions on the leaves of host species belonging to ten genera of seagrasses from around the world, including: Zostera, Heterozostera, Posidonia, Halodule, Cymodocea, Syringodium, Thalassodendron, Ruppia, Thalassia... and Halophila. During their investigations they found that the rapidly expanding, browneblack lesions associated with the disease (Muehlstein et al., 1991) were not always evident in hosts from which Labyrinthula had been isolated, suggesting that pathogen...

  2. Key biogeochemical factors affecting soil carbon storage in Posidonia meadows

    KAUST Repository

    Serrano, Oscar

    2016-08-15

    Biotic and abiotic factors influence the accumulation of organic carbon (C-org) in seagrass ecosystems. We surveyed Posidonia sinuosa meadows growing in different water depths to assess the variability in the sources, stocks and accumulation rates of Corg. We show that over the last 500 years, P. sinuosa meadows closer to the upper limit of distribution (at 2-4 m depth) accumulated 3- to 4-fold higher C-org stocks (averaging 6.3 kg C-org m(-2) at 3- to 4-fold higher rates (12.8 gC(org) m(-2) yr(-1) ) compared to meadows closer to the deep limits of distribution (at 6-8 m depth; 1.8 kg C-org m(-2) and 3.6 g C-org m(-2) yr(-1) . In shallower meadows, C-org stocks were mostly derived from seagrass detritus (88% in average) compared to meadows closer to the deep limit of distribution (45% on average). In addition, soil accumulation rates and fine-grained sediment content (< 0.125 mm) in shallower meadows (2.0 mm yr(-1) and 9 %, respectively) were approximately 2-fold higher than in deeper meadows (1.2 mm yr(-1) and 5 %, respectively). The C-org stocks and accumulation rates accumulated over the last 500 years in bare sediments (0.6 kg C-org m(-2) and 1.2 g C-org m(-2) yr(-1)were 3- to 11-fold lower than in P. sinuosa meadows, while fine-grained sediment content (1 %) and seagrass detritus contribution to the Corg pool (20 %) were 8- and 3-fold lower than in Posidonia meadows, respectively. The patterns found support the hypothesis that Corg storage in seagrass soils is influenced by interactions of biological (e.g., meadow productivity, cover and density), chemical (e.g., recalcitrance of Corg stocks) and physical (e.g., hydrodynamic energy and soil accumulation rates) factors within the meadow. We conclude that there is a need to improve global estimates of seagrass carbon storage accounting for biogeochemical factors driving variability within habitats.

  3. Phenols content and 2-D electrophoresis protein pattern: a promising tool to monitor Posidonia meadows health state

    Directory of Open Access Journals (Sweden)

    Randazzo Davide

    2007-07-01

    Full Text Available Abstract Background The endemic seagrass Posidonia oceanica (L. Delile colonizes soft bottoms producing highly productive meadows that play a crucial role in coastal ecosystems dynamics. Human activities and natural events are responsible for a widespread meadows regression; to date the identification of "diagnostic" tools to monitor conservation status is a critical issue. In this study the feasibility of a novel tool to evaluate ecological impacts on Posidonia meadows has been tested. Quantification of a putative stress indicator, i.e. phenols content, has been coupled to 2-D electrophoretic protein analysis of rhizome samples. Results The overall expression pattern from Posidonia rhizome was determined using a preliminary proteomic approach, 437 protein spots were characterized by pI and molecular weight. We found that protein expression differs in samples belonging to sites with high or low phenols: 22 unique protein spots are peculiar of "low phenols" and 27 other spots characterize "high phenols" samples. Conclusion Posidonia showed phenols variations within the meadow, that probably reflect the heterogeneity of environmental pressures. In addition, comparison of the 2-D electrophoresis patterns allowed to highlight qualitative protein expression differences in response to these pressures. These differences may account for changes in metabolic/physiological pathways as adaptation to stress. A combined approach, based on phenols content determination and 2-D electrophoresis protein pattern, seems a promising tool to monitor Posidonia meadows health state.

  4. Seagrass Ecosystem Services and Their Variability across Genera and Geographical Regions

    Science.gov (United States)

    Mtwana Nordlund, Lina; Barbier, Edward B.; Creed, Joel C.

    2016-01-01

    Threats to and loss of seagrass ecosystems globally, impact not only natural resources but also the lives of people who directly or indirectly depend on these systems. Seagrass ecosystems play a multi-functional role in human well-being, e.g. food through fisheries, control of erosion and protection against floods. Quantifying these services reveals their contributions to human well-being and helps justify seagrass conservation. There has been no comprehensive assessment as to whether seagrass ecosystem services are perceived to vary over the globe or amongst genera. Our study compiles the most complete list of ecosystem services provided by seagrasses so far, including bioregional- and genus-specific information from expert opinion and published studies. Several seagrass ecosystem services vary considerably in their (known) provision across genera and over the globe. Seagrasses genera are clearly not all equal with regard to the ecosystem services they provide. As seagrass genera are not evenly distributed over all bioregions, the presence of an ecosystem service sometimes depends on the genera present. Larger sized seagrass genera (e.g. Posidonia, Enhalus) are perceived to provide more substantial and a wider variety of ecosystem services than smaller species (e.g. Halophila, Lepilaena). Nevertheless, smaller species provide important services. Our findings point out data gaps, provide new insight for more efficient management and recommend caution in economic valuation of seagrass services worldwide. PMID:27732600

  5. Effects of seagrasses and algae of the Caulerpa family on hydrodynamics and particle-trapping rates

    NARCIS (Netherlands)

    Hendriks, I.E.; Bouma, T.J.; Morris, E.P.; Duarte, C.M.

    2010-01-01

    The widespread decline of seagrass beds within the Mediterranean often results in the replacement of seagrasses by opportunistic green algae of the Caulerpa family. Because Caulerpa beds have a different height, stiffness and density compared to seagrasses, these changes in habitat type modify the i

  6. Error, Power, and Blind Sentinels: The Statistics of Seagrass Monitoring

    Science.gov (United States)

    Schultz, Stewart T.; Kruschel, Claudia; Bakran-Petricioli, Tatjana; Petricioli, Donat

    2015-01-01

    We derive statistical properties of standard methods for monitoring of habitat cover worldwide, and criticize them in the context of mandated seagrass monitoring programs, as exemplified by Posidonia oceanica in the Mediterranean Sea. We report the novel result that cartographic methods with non-trivial classification errors are generally incapable of reliably detecting habitat cover losses less than about 30 to 50%, and the field labor required to increase their precision can be orders of magnitude higher than that required to estimate habitat loss directly in a field campaign. We derive a universal utility threshold of classification error in habitat maps that represents the minimum habitat map accuracy above which direct methods are superior. Widespread government reliance on blind-sentinel methods for monitoring seafloor can obscure the gradual and currently ongoing losses of benthic resources until the time has long passed for meaningful management intervention. We find two classes of methods with very high statistical power for detecting small habitat cover losses: 1) fixed-plot direct methods, which are over 100 times as efficient as direct random-plot methods in a variable habitat mosaic; and 2) remote methods with very low classification error such as geospatial underwater videography, which is an emerging, low-cost, non-destructive method for documenting small changes at millimeter visual resolution. General adoption of these methods and their further development will require a fundamental cultural change in conservation and management bodies towards the recognition and promotion of requirements of minimal statistical power and precision in the development of international goals for monitoring these valuable resources and the ecological services they provide. PMID:26367863

  7. Effect of environmental factors (wave exposure and depth) and anthropogenic pressure in the C sink capacity of Posidonia oceanica meadows

    KAUST Repository

    Mazarrasa, Inés

    2017-03-20

    Seagrass are among the most important natural carbon sinks on Earth with Posidonia oceanica (Mediterranean Sea) considered as the most relevant species. Yet, the number of direct measurements of organic carbon burial rates in P. oceanica is still scarce and the effect of local environmental factors remains largely unexplored. In addition, P. oceanica meadows are declining due to the increase in anthropogenic pressure in coastal areas during the last century. The aim of this study is to assess the recent carbon sink capacity of P. oceanica and particularly the effect of human pressure and two environmental factors, water depth and exposure to wave energy (based on a fetch index), on the carbon burial rate since 1900. We conducted an extensive survey of sediment cores in meadows distributed across a gradient of depth, fetch, and human pressure around The Balearic Islands. Sediment and carbon accumulation rates were obtained from 210Pb concentrations profiles. Top-30 centimeters carbon stocks (6.1 ± 1.4 kg C m−2) and burial rates (26 ± 6 g C m−2 yr1) varied up to fivefold across meadows. No significant effect of water depth in carbon burial rates was observed. Although fetch was significantly correlated with sediment mean grain size, confirming the effect of wave exposure in the patterns of sedimentation, fetch alone could not explain the differences in carbon burial rates among the meadows examined. Human pressure affected carbon burial rates, leading to increased rates since the onset of the rise in anthropogenic pressure, particularly so in sheltered meadows supporting high human pressure.

  8. Linking plant communities on land and at sea: The effects of Posidonia oceanica wrack on the structure of dune vegetation

    Science.gov (United States)

    Del Vecchio, Silvia; Jucker, Tommaso; Carboni, Marta; Acosta, Alicia T. R.

    2017-01-01

    Although terrestrial and marine ecosystems are often perceived as clearly distinct, in coastal areas biological communities on land and at sea are in fact intimately linked. One way in which terrestrial and marine systems interact is through the accumulation of seagrass wrack on beaches, which plays an important role as a nutrient input in coastal dune food webs. Here we test whether accumulated beach-cast wrack also influences the structure and diversity of coastal dune plant communities. Relying on a database of 572 vegetation surveys distributed across the island of Sardinia, we used mixed-effects models to compare the vegetation cover and species richness of plant communities exposed to different amounts of Posidonia oceanica beach-cast wrack. We found that beaches which receive high amounts of P. oceanica wrack have considerably greater vegetation cover (10% on average) than those with fewer deposits. The positive relationship between beach-cast wrack and vegetation cover was especially strong in nearshore plant communities, becoming progressively weaker along the habitat zonation. A similar pattern was found for species richness: beaches with high levels of accumulated wrack had more diverse drift line and foredune plant communities, while habitats further away from the shoreline were unaffected. Our study is the first to present evidence suggesting that activities which reduce wrack accumulation on beaches - either through direct removal of deposits or by causing P. oceanica seabeds to decline - can have effects on both the structure and diversity of coastal dune plant communities. Effective management of Mediterranean coastal dune ecosystems will require developing clear strategies for the removal and relocation of accumulated beach-cast wrack.

  9. Real-Time Classification of Seagrass Meadows on Flat Bottom with Bathymetric Data Measured by a Narrow Multibeam Sonar System

    Directory of Open Access Journals (Sweden)

    Masahiro Hamana

    2016-01-01

    Full Text Available Seagrass meadows, one of the most important habitats for many marine species, provide essential ecological services. Thus, society must conserve seagrass beds as part of their sustainable development efforts. Conserving these ecosystems requires information on seagrass distribution and relative abundance, and an efficient, accurate monitoring system. Although narrow multibeam sonar systems (NMBSs are highly effective in resolving seagrass beds, post-processing methods are required to extract key data. The purpose of this study was to develop a simple method capable of detecting seagrass meadows and estimating their relative abundance in real time using an NMBS. Because most seagrass meadows grow on sandy seafloors, we proposed a way of discriminating seagrass meadows from the sand bed. We classify meadows into three categories of relative seagrass abundance using the 95% confidence level of beam depths and the depth range of the beam depth. These are respectively two times the standard deviation of beam depths, and the difference between the shallowest and the deepest depths in a 0.5 × 0.5 m grid cell sampled with several narrow beams. We examined Zostera caulescens Miki, but this simple NMBS method of seagrass classification can potentially be used to map seagrass meadows with longer shoots of other species, such as Posidonia, as both have gas filled cavities.

  10. The use of banquettes of Posidonia oceanica as a source of fiber and minerals in ruminant nutrition. An observational study.

    Science.gov (United States)

    Castillo, C; Mantecón, A R; Sotillo, J; Benedito, J L; Abuelo, A; Gutiérrez, C; Hernández, J

    2014-10-01

    In the search for new food sources that contribute to the optimization of livestock production this paper discusses the possibility of using waste (called banquettes) of a marine plant commonly found on the Mediterranean coasts: Posidonia oceanica. The idea stems from the use of a waste that in summertime generates large costs because it is considered bothersome on the beaches. Thus, tons and tons of residues are collected each year from the beach, being destined for incineration. However, alternative uses for these residues are suggested, such as forage that is particularly relevant for the Mediterranean coast, where the weather does not support abundant grass growth. With this purpose, samples of banquettes of P. oceanica from six different points of a touristic place located in the Murcia Region (S.E. of Spain) were collected in April 2012 on the same day directly from the beach above the water line, washed with distilled water and sun-dried for 48 h. Approximately 500 g of each sample of plant material was chopped and two subsamples of 200 g each were placed in airtight plastic containers and sent to the laboratory for mineral and chemical analysis. This report provides data on the nutritional composition of P. oceanica such as mineral contents (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) and chemical composition (ash, CP, ether extract (EE), NDF and ADF, respectively) and ADL. Finally, the in sacco rumen disappearance of dry matter (DM), organic matter (OM), CP and NDF were studied. Our results showed that minerals, except for Fe, where within the range of values reported for P. oceanica in other parts of the Mediterranean region. Given the high Fe content further studies assessing the antagonic Fe-Cu interaction and its effect on animal health should be addressed. In relation to chemical composition, it is clear that this seagrass is a poor protein source and has levels of DM degradability at 24 h, similar to those obtained for cereal straw. The information

  11. Using modelling to predict impacts of sea level rise and increased turbidity on seagrass distributions in estuarine embayments

    Science.gov (United States)

    Davis, Tom R.; Harasti, David; Smith, Stephen D. A.; Kelaher, Brendan P.

    2016-11-01

    Climate change induced sea level rise will affect shallow estuarine habitats, which are already under threat from multiple anthropogenic stressors. Here, we present the results of modelling to predict potential impacts of climate change associated processes on seagrass distributions. We use a novel application of relative environmental suitability (RES) modelling to examine relationships between variables of physiological importance to seagrasses (light availability, wave exposure, and current flow) and seagrass distributions within 5 estuarine embayments. Models were constructed separately for Posidonia australis and Zostera muelleri subsp. capricorni using seagrass data from Port Stephens estuary, New South Wales, Australia. Subsequent testing of models used independent datasets from four other estuarine embayments (Wallis Lake, Lake Illawarra, Merimbula Lake, and Pambula Lake) distributed along 570 km of the east Australian coast. Relative environmental suitability models provided adequate predictions for seagrass distributions within Port Stephens and the other estuarine embayments, indicating that they may have broad regional application. Under the predictions of RES models, both sea level rise and increased turbidity are predicted to cause substantial seagrass losses in deeper estuarine areas, resulting in a net shoreward movement of seagrass beds. Seagrass species distribution models developed in this study provide a valuable tool to predict future shifts in estuarine seagrass distributions, allowing identification of areas for protection, monitoring and rehabilitation.

  12. Effects of fish farming on flavonoids in Posidonia oceanica.

    Science.gov (United States)

    Cannac, Magali; Ferrat, Lila; Pergent-Martini, Christine; Pergent, Gerard; Pasqualini, Vanina

    2006-10-15

    This work is a first approach to flavonoid responses (total proanthocyanidins and total and simple flavonols) in Posidonia oceanica in function of nutrient enrichment (aquaculture activities - fish farming), in the western Mediterranean Sea (Calvi-Corsica-France). The first result is the presence of total and simple flavonoids in P. oceanica. The second result shows an increase in total proanthocyanidin and total flavonol concentrations near cages, which would be linked to the high grazing pressure induced by meadow enrichment. Concerning simple flavonols, only quercetin shows a response to fish farming, which could be due to its strong antioxidant capacity. The presence of fish farming, which causes variations in environmental parameters, could affect the functioning of P. oceanica meadows. Flavonoid concentrations in P. oceanica seem to be a possible bioindicator of nutrient enrichment for the management of the littoral environment.

  13. Landscape configuration modulates carbon storage in seagrass sediments

    Science.gov (United States)

    Ricart, Aurora M.; Pérez, Marta; Romero, Javier

    2017-02-01

    Climate change has increased interest in seagrass systems as natural carbon sinks and recent studies have estimated the carbon stocks associated with seagrass meadows. However, the factors that affect their variability remain poorly understood. This paper assesses how landscape-level attributes (patch size and matrix composition) influence carbon storage in seagrass sediments. We quantified the organic carbon (Corg) content and other geochemical properties (δ13C and particle size) in surface sediments of continuous Posidonia oceanica meadows, patchy meadows interspersed with rocky-algal reefs and patchy meadows on sedimentary bottoms. We also took samples of potential carbon sources for isotopic composition determination. Our results indicate that the continuous meadows accumulated larger amounts of Corg than patchy meadows, whether embedded in a rock or sand matrix. The Corg from continuous meadows was also more 13C enriched, which suggests that a high proportion of the carbon was derived from plant material (autochthonous sources); in contrast in patchy meadows (especially in a sand matrix), lower δ13C values indicated a higher contribution from allochthonous sources (mainly suspended particulate organic matter, SPOM). These findings suggest that the sediment of continuous meadows stores more Corg in than that of patchy meadows. This is probably due to the increased contribution from seagrass leaves, which are much more refractory than SPOM. In general, certain landscape configurations, and especially patchiness, appear to reduce the carbon storage capacity of seagrasses. Since the current decline of seagrass is leading to habitat fragmentation, our results increase the argument for the promotion of effective measures to preserve the integrity of these natural carbon sinks.

  14. Can mud (silt and clay) concentration be used to predict soil organic carbon content within seagrass ecosystems?

    Science.gov (United States)

    Serrano, Oscar; Lavery, Paul S.; Duarte, Carlos M.; Kendrick, Gary A.; Calafat, Antoni; York, Paul H.; Steven, Andy; Macreadie, Peter I.

    2016-09-01

    The emerging field of blue carbon science is seeking cost-effective ways to estimate the organic carbon content of soils that are bound by coastal vegetated ecosystems. Organic carbon (Corg) content in terrestrial soils and marine sediments has been correlated with mud content (i.e., silt and clay, particle sizes soil Corg content. We also combined these data with the δ13C signatures of the soil Corg to understand the sources of Corg stores. The results showed that mud is positively correlated with soil Corg content only when the contribution of seagrass-derived Corg to the sedimentary Corg pool is relatively low, such as in small and fast-growing meadows of the genera Zostera, Halodule and Halophila, and in bare sediments adjacent to seagrass ecosystems. In large and long-living seagrass meadows of the genera Posidonia and Amphibolis there was a lack of, or poor relationship between mud and soil Corg content, related to a higher contribution of seagrass-derived Corg to the sedimentary Corg pool in these meadows. The relatively high soil Corg contents with relatively low mud contents (e.g., mud-Corg saturation) in bare sediments and Zostera, Halodule and Halophila meadows was related to significant allochthonous inputs of terrestrial organic matter, while higher contribution of seagrass detritus in Amphibolis and Posidonia meadows disrupted the correlation expected between soil Corg and mud contents. This study shows that mud is not a universal proxy for blue carbon content in seagrass ecosystems, and therefore should not be applied generally across all seagrass habitats. Mud content can only be used as a proxy to estimate soil Corg content for scaling up purposes when opportunistic and/or low biomass seagrass species (i.e., Zostera, Halodule and Halophila) are present (explaining 34 to 91 % of variability), and in bare sediments (explaining 78 % of the variability). The results obtained could enable robust scaling up exercises at a low cost as part of blue carbon

  15. Advances in micro-cartography: A two-dimensional photo mosaicing technique for seagrass monitoring

    Science.gov (United States)

    Rende, S. F.; Irving, A. D.; Bacci, T.; Parlagreco, L.; Bruno, F.; De Filippo, F.; Montefalcone, M.; Penna, M.; Trabucco, B.; Di Mento, R.; Cicero, A. M.

    2015-12-01

    Seagrass meadows are complex ecosystems representing an important source of biodiversity for coastal marine systems, but are subjected to numerous threats from natural and human-based influences. Due to their susceptibility to changing environmental conditions, seagrasses are habitually used in monitoring programmes as biological indicators to assess the ecological status of coastal environments. In this paper we used a non-destructive photo mosaicing technology to quantify seagrass distribution and abundance, and explore benefits of micro-cartographic analysis. Furthermore, the use of photogrammetric tools enhanced the method, which proved to be efficient due to its use of low-cost instruments and its simplicity of implementation. This paper describes the steps required to use this method in meadows of Posidonia oceanica, including: i) camera calibration procedures, ii) programming of video survey, iii) criteria to perform sampling activities, iv) data processing and micro-georeferenced maps restitution, and v) possible study applications.

  16. Impact of {sup 134}Cs and {sup 137}Cs from the Chernobyl reactor accident on the Spanish Mediterranean marine environment

    Energy Technology Data Exchange (ETDEWEB)

    Molero, J.; Sanchez-Cabeza, J.A.; Merino, J. [Grup de Fisica de les Radiacions, Departament de Fisica, Facultat de Ciencies, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Mitchell, P.I. [Laboratory of Radiation Physics, University College, Dublin (Ireland); Vidal-Quadras, A. [Grup de Fisica de les Radiacions, Departament de Fisica, Facultat de Ciencies, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain)

    1999-05-01

    As part of a study aiming to establish the distribution and bioavailability of man-made radionuclides in the marine environment, radiocaesium levels were determined in large volume sea water samples and in the sea-grass Posidonia oceanica collected along the Spanish Mediterranean coast. Results obtained from 1987 to 1991 showed the enhancement of radiocaesium levels in the Spanish Mediterranean marine environment after the Chernobyl accident. The well-known {sup 134}Cs/{sup 137}Cs isotopic ratio in Chernobyl fresh deposition was used to identify the weapon tests fall-out and Chernobyl deposition components. {sup 137}Cs and {sup 134}Cs mean concentrations in surface waters from the Spanish Mediterranean shoreline were 4.8{+-}0.2 and 0.27{+-}0.01 Bq m{sup -3}, respectively. {sup 137}Cs concentration incorporated into Mediterranean waters as a consequence of the post-Chernobyl deposition was estimated to be 1.16{+-}0.04 Bq m{sup -3}, which is a 33{+-}2% increase over the previous levels. {sup 137}Cs estimated inventory in the surface water layer (0-50 m) of the Catalan-Balearic basin was 17.4{+-}0.5 TBq for {sup 137}Cs, of which 4.3{+-}0.2 TBq must be attributed to post-Chernobyl deposition, and 1.00{+-}0.04 TBq for {sup 134}Cs. Activation and fission products such as {sup 106}Ru, {sup 110m}Ag, {sup 134}Cs, {sup 137}Cs and {sup 144}Ce, were detected in all samples of Posidonia oceanica. Mean radiocaesium levels in the bioindicator were 1.02{+-}0.25 and 0.20{+-}0.03 Bq kg{sup -1} for {sup 137}Cs and {sup 134}Cs, respectively, corresponding to a mean isotopic ratio {sup 134}Cs/{sup 137}Cs equal to 0.20{+-}0.04 (1987). {sup 137}Cs activity incorporated by Posidonia oceanica after the Chernobyl deposition over the Mediterranean Sea was estimated as 0.51{+-}0.08 Bq kg{sup -1}. Therefore, {sup 137}Cs specific activity had increased 100{+-}40% one year after the accident. Low level radioactive liquid effluents from the nuclear power plants located on the southern Catalan

  17. Habitat and scale shape the demographic fate of the keystone sea urchin Paracentrotus lividus in Mediterranean macrophyte communities.

    Directory of Open Access Journals (Sweden)

    Patricia Prado

    Full Text Available Demographic processes exert different degrees of control as individuals grow, and in species that span several habitats and spatial scales, this can influence our ability to predict their population at a particular life-history stage given the previous life stage. In particular, when keystone species are involved, this relative coupling between demographic stages can have significant implications for the functioning of ecosystems. We examined benthic and pelagic abundances of the sea urchin Paracentrotus lividus in order to: 1 understand the main life-history bottlenecks by observing the degree of coupling between demographic stages; and 2 explore the processes driving these linkages. P. lividus is the dominant invertebrate herbivore in the Mediterranean Sea, and has been repeatedly observed to overgraze shallow beds of the seagrass Posidonia oceanica and rocky macroalgal communities. We used a hierarchical sampling design at different spatial scales (100 s, 10 s and <1 km and habitats (seagrass and rocky macroalgae to describe the spatial patterns in the abundance of different demographic stages (larvae, settlers, recruits and adults. Our results indicate that large-scale factors (potentially currents, nutrients, temperature, etc. determine larval availability and settlement in the pelagic stages of urchin life history. In rocky macroalgal habitats, benthic processes (like predation acting at large or medium scales drive adult abundances. In contrast, adult numbers in seagrass meadows are most likely influenced by factors like local migration (from adjoining rocky habitats functioning at much smaller scales. The complexity of spatial and habitat-dependent processes shaping urchin populations demands a multiplicity of approaches when addressing habitat conservation actions, yet such actions are currently mostly aimed at managing predation processes and fish numbers. We argue that a more holistic ecosystem management also needs to incorporate the

  18. Spatio-temporal variability of Borer Polychaetes in Posidonia oceanica beds and its relation to meadow structure

    Directory of Open Access Journals (Sweden)

    C. VASAPOLLO

    2015-01-01

    Full Text Available Posidonia oceanica forms an extremely productive and complex ecosystem in the coastal Mediterranean Sea providing a suitable habitat for hundreds of plant and animal species. Among motile invertebrates associated to Posidonia meadows,  polychaete borers of the plant sheaths represent a unique group which exploit a peculiar microhabitat. They belong to the family Eunicidae with three dominant species, Lysidice collaris, L. ninetta and L. unicornis. Due to their strong association with Posidonia shoots, these animals are particularly suitable to study the plant and animal spatial relationships and their pattern of variability. The aim of this work was to evaluate the frequency of occurrence of these animals (Index of Borer, IB at different spatial and temporal (summer vs winter scales in two Posidonia meadows off the Ischia Island (Gulf of Naples, Italy, which are exposed to different degrees of human impact and of hydrological conditions. Results showed IB values of L. collaris (the most abundant species significantly different between meadows and at scales from 10s to 100s of meters, as well as between summer and winter. The IB of L. ninetta showed significant differences only at scales of 10s of meters while, on the contrary, the IB of L. unicornis (the less abundant species did not show variability at any spatial and temporal scales. Most of the variance was at the more impacted and less water movement exposed meadow, suggesting higher level of small and intermediate scales of patchiness of borers at this meadow. These variation patterns  are discussed in relation  to local environmental differences between the studied Posidonia beds.

  19. Ecoregion-Based Conservation Planning in the Mediterranean: Dealing with Large-Scale Heterogeneity

    Science.gov (United States)

    Giakoumi, Sylvaine; Sini, Maria; Gerovasileiou, Vasilis; Mazor, Tessa; Beher, Jutta; Possingham, Hugh P.; Abdulla, Ameer; Çinar, Melih Ertan; Dendrinos, Panagiotis; Gucu, Ali Cemal; Karamanlidis, Alexandros A.; Rodic, Petra; Panayotidis, Panayotis; Taskin, Ergun; Jaklin, Andrej; Voultsiadou, Eleni; Webster, Chloë; Zenetos, Argyro; Katsanevakis, Stelios

    2013-01-01

    Spatial priorities for the conservation of three key Mediterranean habitats, i.e. seagrass Posidonia oceanica meadows, coralligenous formations, and marine caves, were determined through a systematic planning approach. Available information on the distribution of these habitats across the entire Mediterranean Sea was compiled to produce basin-scale distribution maps. Conservation targets for each habitat type were set according to European Union guidelines. Surrogates were used to estimate the spatial variation of opportunity cost for commercial, non-commercial fishing, and aquaculture. Marxan conservation planning software was used to evaluate the comparative utility of two planning scenarios: (a) a whole-basin scenario, referring to selection of priority areas across the whole Mediterranean Sea, and (b) an ecoregional scenario, in which priority areas were selected within eight predefined ecoregions. Although both scenarios required approximately the same total area to be protected in order to achieve conservation targets, the opportunity cost differed between them. The whole-basin scenario yielded a lower opportunity cost, but the Alboran Sea ecoregion was not represented and priority areas were predominantly located in the Ionian, Aegean, and Adriatic Seas. In comparison, the ecoregional scenario resulted in a higher representation of ecoregions and a more even distribution of priority areas, albeit with a higher opportunity cost. We suggest that planning at the ecoregional level ensures better representativeness of the selected conservation features and adequate protection of species, functional, and genetic diversity across the basin. While there are several initiatives that identify priority areas in the Mediterranean Sea, our approach is novel as it combines three issues: (a) it is based on the distribution of habitats and not species, which was rarely the case in previous efforts, (b) it considers spatial variability of cost throughout this

  20. SEAGRASS RHIZOSPHERE MICROBIAL COMMUNITIES

    Science.gov (United States)

    Devereux, Richard. 2005. Seagrass Rhizosphere Microbial Communities. In: Interactions Between Macro- and Microorganisms in Marine Sediments. E. Kristense, J.E. Kostka and R.H. Haese, Editors. American Geophysical Union, Washington, DC. p199-216. (ERL,GB 1213). Seagrasses ...

  1. Non-native seagrass

    NARCIS (Netherlands)

    van Tussenbroek, B.I.; van Katwijk, M.M.; Bouma, T.J.; van der Heide, T.; Govers, L.L.; Leuven, R.S.E.W.

    2016-01-01

    Seagrasses comprise 78 species and are rarely invasive. But the seagrass Halophila stipulacea, firstly recorded in the Caribbean in the year 2002, has spread quickly throughout the region. Previous works have described this species as invasive in the Caribbean, forming dense mats that exclude native

  2. Invertebrate response to nutrient-driven epiphytic load increase in Posidonia oceanica meadows

    Science.gov (United States)

    Castejón-Silvo, Inés; Domínguez, Marta; Terrados, Jorge; Tomas, Fiona; Morales-Nin, Beatriz

    2012-10-01

    Nutrient increases in coastal systems are becoming a world-wide concern since they promote strong structural and functional changes in shallow ecosystems. Increased nutrient availability in the water column may strongly enhance the leaf epiphytic communities of key habitat-forming species such as seagrasses through a bottom-up mechanism, competing for light and nutrients with the leaves. Epiphytes support an abundant and diverse community of resident invertebrates which fuel higher trophic levels in Posidonia oceanica food webs. We evaluated the response of seagrass, epiphytes and the invertebrate community to an experimental increase of water column nutrient availability. Nutrient increase was followed by a rise of epiphyte biomass. The increase in epiphytic biomass promoted invertebrate abundance, but appeared to have negative effects on P. oceanica shoot size. On the other hand, the increase in invertebrate abundance did not seem to control epiphytic biomass, which was not reversed to pre-nutrient enrichment levels. This work suggests that the abundance of invertebrate populations is limited by epiphyte biomass, through food or habitat provision, in P. oceanica systems and points to nutrients as the main driver of epiphyte biomass during summer. The results illustrate the control mechanisms at community level in P. oceanica meadows and the possible responses of a threatened ecosystem to human impact such as eutrophication.

  3. Composition of epiphytic leaf community of Posidonia oceanica as a tool for environmental biomonitoring

    Science.gov (United States)

    Martínez-Crego, Begoña; Prado, Patricia; Alcoverro, Teresa; Romero, Javier

    2010-06-01

    The demand for sensitive biological tools to assess the environmental quality of coastal waters at broad spatial scales is increasing. Many of the tools used are based on the taxonomic composition of biotic assemblages. They usually require a valuable taxonomic expertise while are unique reflecting the overall ecosystem integrity. Here, we evaluate the potential indicator value of several features of the epiphytic community (overall assemblage composition, species richness, and proportion of the main taxonomic groups) growing on the seagrass Posidonia oceanica leaves. We do so by empirically examining their changes along a disturbance gradient where multiple human activities have interactive and cumulative impacts, sampling at different spatial scales and at two different depths (5 and 15 m). Our results show that the specific composition of the epiphytic assemblages (i.e. species composition) closely reflects, in the deep meadows, the combined effects of different anthropogenic stressors along the gradient, showing an integrative and non-specific response. Similarly, an increase in the proportion of hydrozoans, and a decrease in the proportion of rhodophytes and chlorophytes are observed in deep meadows along the gradient. In shallow meadows, grazing and biotic features of the seagrass seem the main forcing factors determining species composition, and therefore masking the response of epiphytes to the deterioration gradient. After address the effect of natural sources of variability (water depth, within- and between-meadow heterogeneity), changes in epiphyte assemblages and in the proportion of hydrozoans, rhodophytes and chlorophytes in relatively deep meadows seem promising monitoring tools for detecting coastal environmental deterioration.

  4. Acclimation to different depths by the marine angiosperm Posidonia oceanica: transcriptomic and proteomic profiles

    Directory of Open Access Journals (Sweden)

    Emanuela eDattolo

    2013-06-01

    Full Text Available For seagrasses, seasonal and daily variations in light and temperature represent the mains factors driving their distribution along the bathymetric cline. Changes in these environmental factors, due to climatic and anthropogenic effects, can compromise their survival. In a framework of conservation and restoration, it becomes crucial to improve our knowledge about the physiological plasticity of seagrass species along environmental gradients. Here, we aimed to identify differences in transcriptomic and proteomic profiles, involved in the acclimation along the depth gradient in the seagrass Posidonia oceanica, and to improve the available molecular resources in this species, which is an important requisite for the application of eco-genomic approaches. To do that, from plant growing in the shallow (-5m and a deep (-25m portions of a single meadow, (i we generated two reciprocal EST (Expressed Sequences Tags libraries using a Suppressive Subtractive Hybridization (SSH approach, to obtain depth/specific transcriptional profiles, and (ii we identified proteins differentially expressed, using the highly innovative USIS mass spectrometry methodology, coupled with 1D-SDS electrophoresis and labeling free approach. Mass spectra were searched in the open source Global Proteome Machine (GPM engine against plant databases and with the X!Tandem algorithm against a local database. Transcriptional analysis showed both quantitative and qualitative differences between depths. EST libraries had only the 3% of transcripts in common. A total of 315 peptides belonging to 64 proteins were identified by mass spectrometry. ATP synthase subunits were among the most abundant proteins in both conditions. Both approaches identified genes and proteins in pathways related to energy metabolism, transport and genetic information processing, that appear o be the most involved in depth acclimation in P. oceanica. Their putative rules in acclimation to depth were discussed.

  5. Characterization and cartography of some Mediterranean soft-bottom benthic communities (Ligurian Sea, Italy

    Directory of Open Access Journals (Sweden)

    A. Somaschini

    1998-06-01

    Full Text Available Soft-bottom benthic communities were studied along the Western coast of the Ligurian Sea with a new approach using both videocamera surveys and collected samples. The preliminary distribution of soft-bottoms and the definition of the limits and status of seagrass beds were carried out in September 1991, using an underwater vehicle provided with a videocamera and towed by a boat. Moreover, 90 benthic samples were collected at 5-40 m depth in order to characterize the macrobenthic soft-bottom communities. Six soft-bottom benthic assemblages and two sea grass biotopes (Cymodocea nodosa and Posidonia oceanica were revealed by means of underwater images and multivariate analysis (TWINSPAN on samples collected. The communities inhabiting the infralittoral sandy and coarse sediments corresponded to those previously described in the Mediterranean Sea, whereas a large complex transition between sandy and muddy communities was recognized on circalittoral soft-bottoms. Information obtained with this approach was used to draw a map of the investigated areas at 1:10,000 scale. The employment of the two techniques was cost effective for both time and research effort.

  6. Measurement of arsenic compounds in littoral zone algae from the Western Mediterranean Sea. Occurrence of arsenobetaine.

    Science.gov (United States)

    Llorente-Mirandes, Toni; Ruiz-Chancho, Maria José; Barbero, Mercedes; Rubio, Roser; López-Sánchez, José Fermín

    2010-11-01

    The determination of arsenic compounds in algae collected on the Catalan coast (Western Mediterranean) is reported. Ten algae species and the seagrass Posidonia oceanica were analyzed. Total arsenic in the samples was determined by microwave digestion and inductively coupled plasma mass spectrometry (ICPMS). Arsenic speciation in water extracts of samples was analyzed by liquid chromatography with both anionic and cationic exchange with ICPMS detection (LC-ICPMS). The total arsenic content of the algae samples ranged from 2.96 to 39.0mg As kg(-1). The following compounds were detected: arsenite (As(III)), arsenate (As(V)), methylarsonate (MA), dimethylarsinate (DMA), sulfonate sugar (SO3-sug), sulfate sugar (SO4-sug), phosphate sugar (PO4-sug), arsenobetaine (AB), arsenocholine (AC), trimethylarsine oxide (TMAO) and glycerol sugar (Gly-sug). The main arsenic species found were arsenosugars. Significant percentages of arsenobetaine (0.54 mg As kg(-1), 28% of the extractable arsenic and 0.39 mg As kg(-1), 18% of the extractable arsenic) were found in Ulva rigida and Enteromorpha compressa. These results are discussed in relation to the presence of epiphytes. Copyright © 2010 Elsevier Ltd. All rights reserved.

  7. Seagrass distribution off California

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are a compilation of currently available seagrass GIS data sets for the west coast of the United States. These data have been compiled from seventeen...

  8. Predictive Seagrass Habitat Model

    Science.gov (United States)

    Restoration of ecosystem services provided by seagrass habitats in estuaries requires a firm understanding of the modes of action of multiple interacting stressors including nutrients, climate change, coastal land-use change, and habitat modification. We explored the application...

  9. Johnsons Seagrass Critical Habitat

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data represent the critical habitat for Johnson's Seagrass as designated by Federal Register Vol. 65, No. 66, Wednesday, April 5, 2000, Rules and Regulations.

  10. The seagrasses of India

    Digital Repository Service at National Institute of Oceanography (India)

    Jagtap, T.G.; Komarpant, D.S.; Rodrigues, R.

    kinds of biota, and produce a considerable amount of organic matter, a major energy source in the coastal marine food web; they playa significant role in nutrient regeneration and shore stabilization processes. The major seagrass meadows in India exist... of awareness, limited distribution and rising anthropo genic pressures, it is imperative to deveLop a national educationaL and conservation management pLan for the seagrass ecosystem with the following objectives: a quantification, mapping and regular...

  11. Posidonia oceanica L. (Delile) Meadow from Messioua

    OpenAIRE

    Sammari, Ch.; Hattour, A.; Komatsu, T; Zarrouk, S; Ben Mustapha, K.; El Abed, A.

    2002-01-01

    In order to study the benthic ecology of the “Messioua banc” (30 NM east off Zarzis, Southern Tunisia), a traditional Tunisian sponge fishing ground, four marine campaigns were conducted with the R/V “Hannibal” from October 2000 to August 2001. The objectives of three of these campaigns were field validation, focusing on the sampling of the Posidonia oceanica meadow and of the sponge population. However the goal of the fourth one, with the use of a multi-beam sonar SEABAT 9001 (Reson Co.), wa...

  12. Can mud (silt and clay) concentration be used to predict soil organic carbon content within seagrass ecosystems?

    KAUST Repository

    Serrano, Oscar

    2016-09-07

    The emerging field of blue carbon science is seeking cost-effective ways to estimate the organic carbon content of soils that are bound by coastal vegetated ecosystems. Organic carbon (C-org) content in terrestrial soils and marine sediments has been correlated with mud content (i.e., silt and clay, particle sizes <63 mu m), however, empirical tests of this theory are lacking for coastal vegetated ecosystems. Here, we compiled data (n = 1345) on the relationship between C-org and mud contents in seagrass ecosystems (79 cores) and adjacent bare sediments (21 cores) to address whether mud can be used to predict soil C-org content. We also combined these data with the delta C-13 signatures of the soil C-org to understand the sources of Corg stores. The results showed that mud is positively correlated with soil C-org content only when the contribution of seagrass-derived C-org to the sedimentary C-org pool is relatively low, such as in small and fast-growing meadows of the genera Zostera, Halodule and Halophila, and in bare sediments adjacent to seagrass ecosystems. In large and long-living seagrass meadows of the genera Posidonia and Amphibolis there was a lack of, or poor relationship between mud and soil C-org content, related to a higher contribution of seagrass-derived C-org to the sedimentary C-org pool in these meadows. The relatively high soil C-org contents with relatively low mud contents (e.g., mud-C-org saturation) in bare sediments and Zostera, Halodule and Halophila meadows was related to significant allochthonous inputs of terrestrial organic matter, while higher contribution of seagrass detritus in Amphibolis and Posidonia meadows disrupted the correlation expected between soil C-org and mud contents. This study shows that mud is not a universal proxy for blue carbon content in seagrass ecosystems, and therefore should not be applied generally across all seagrass habitats. Mud content can only be used as a proxy to estimate soil C-org content for

  13. Ion concentrations in seagrass: A comparison of results from field and controlled-environment studies

    Science.gov (United States)

    Garrote-Moreno, Aurora; Cambridge, Marion; Sánchez-Lizaso, Jose Luis

    2016-11-01

    Osmoregulation is essential for the survival of seagrasses in marine and hypersaline environments. The aim of this study was to examine ion concentrations of four seagrass species (Posidonia australis, P. sinuosa, Amphibolis antarctica and A. griffithii) after exposure to salinity changes. Plant fragments were placed in a series of aquaria at marine salinity (35) and, after one week of acclimation, exposed for 7 days to salinities between 20 and 70. Cl-, Na+ and total ion concentration increased with salinity in leaf tissue of the four seagrasses species. These results were compared with those of P. australis and A. antarctica samples collected at three locations at Shark Bay, Western Australia where higher salinities occurred, ranging from 46 to 51. Concentrations of K+ and Ca+2 were higher in seagrass tissues from Shark Bay than in those in aquarium trials. Cl-, Na+ and total ions in P. australis and A. antarctica from Shark Bay were lowest at the highest salinity location. The K+/Na+ ratio in the aquarium trials (under ambient conditions) was in the following order: A. antarctica = A. griffithii > P. australis > P. sinuosa and Ca+2/Na+ ratio was: A. antarctica = A. griffithii > P. sinuosa > P. australis. This species order indicates a physiological capacity to tolerate variation in salinity. Furthermore, these ratios were higher in the locality with highest salinity in Shark Bay, indicating acclimation and adaptation of ion concentrations to the salinity regime in the environment.

  14. Seagrass sediments reveal the long-term deterioration of an estuarine ecosystem.

    Science.gov (United States)

    Serrano, Oscar; Lavery, Paul; Masque, Pere; Inostroza, Karina; Bongiovanni, James; Duarte, Carlos

    2016-04-01

    The study of a Posidonia australis sediment archive has provided a record of ecosystem dynamics and processes over the last 600 years in Oyster Harbour (SW Australia). Ecosystem shifts are a widespread phenomenon in coastal areas, and this study identifies baseline conditions and the time-course of ecological change (cycles, trends, resilience and thresholds of ecosystem change) under environmental stress in seagrass-dominated ecosystem. The shifts in the concentrations of chemical elements, carbonates, sediments seagrass area at Oyster Harbour was lost during the second phase of environmental degradation (1960s until present). The sharp increase in P concentration and the increasing contribution of algae and terrestrial inputs into the sedimentary organic matter pool around 1960s provides compelling evidence of the documented eutrophication of the estuary and the subsequent loss of seagrass meadows. The results presented demonstrate the power of seagrass sedimentary archives to reconstruct the trajectories of anthropogenic pressures on estuarine ecosystem and the associated regime shifts, which can be used to improve the capacity of scientists and environmental managers to understand, predict and better manage ecological change in these ecosystems.

  15. Density, size structure, shell orientation and epibiontic colonization of the fan mussel Pinna nobilis L. 1758 (Mollusca: Bivalvia in three contrasting habitats in an estuarine area of Sardinia (W Mediterranean

    Directory of Open Access Journals (Sweden)

    Piero Addis

    2009-03-01

    Full Text Available We investigated the spatial distribution, size structure, shell orientation and valve colonization by epibionts of the endangered Mediterranean bivalve Pinna nobilis in three continuous but different habitats in the Gulf of Oristano (Sardinia, western Mediterranean. The sampling stations chosen were: an estuarine area (E of coastal salt-marshes characterized by unvegetated sea-bottoms; and two areas in a seagrass meadow characterized by an extensive Posidonia oceanica meadow (Mw and patched mixed meadows of P. oceanica and Cymodocea nodosa (Me. We found significant differences in mean densities among stations and the highest value was found in the estuarine area. Shell orientation showed that there was uniform circular distribution of specimens in the Mw station and a unimodal distribution in the Me and E stations, where specimens were set at 0°N and 10°NNE, which is a pattern related to sea drift. Shell epibiosis displayed differences between habitats. The highest valve colonization was in the estuary, with filamentous dark algae and Ostrea edulis reaching almost 90 percent of shell coverage. This study provides new information on habitat preferences and data for assessing local populations of P. nobilis that is useful for its conservation and improving the knowledge of its ecology.

  16. First results on the study of metal contamination along the Corsican coastline using Posidonia oceanica.

    Science.gov (United States)

    Lafabrie, C; Pergent-Martini, C; Pergent, G

    2008-01-01

    This study aims at determining the metal concentrations in blades and sheaths of Posidonia oceanica adult leaves, in 16 stations of the Corsican coastline. It shows that except for Cr, all the metals are preferentially accumulated in the blades. This result is particularly interesting as it means that trace metals analyses may be carried out only on the blades avoiding thus the removal of the shoots. Moreover, this study shows that metal concentrations generally fall within the range of the lowest values available in literature and may reflect the "background noise" of the Mediterranean. Station 15 (Canari) can however be distinguished from the others due to its high Co, Cr and Ni concentrations. This result may be related to the presence of a previous asbestos mine, located near this station. Therefore, this study reinforces the relevance of the use of P. oceanica as a tracer of metal contamination.

  17. Photosynthetic activity buffers ocean acidification in seagrass meadows

    Directory of Open Access Journals (Sweden)

    I. E. Hendriks

    2013-07-01

    Full Text Available Macrophytes growing in shallow coastal zones characterized by intense metabolic activity have the capacity to modify pH within their canopy and beyond. We observed diel pH ranges is in shallow (5–12 m seagrass (Posidonia oceanica meadows from 0.06 pH units in September to 0.24 units in June. The carbonate system (pH, DIC, and aragonite saturation state (ΩAr and O2 within the meadows displayed strong diel variability driven by primary productivity, and changes in chemistry were related to structural parameters of the meadow, in particular, the leaf surface area available for photosynthesis (LAI. LAI was positively correlated to mean and max pHNBS and max ΩAr. Oxygen production positively influenced the range and maximum pHNBS and the range of ΩAr. In June, vertical mixing (as Turbulent Kinetic Energy influenced ΩAr, while in September there was no effect of hydrodynamics on the carbonate system within the canopy. ΩAr was positively correlated with the calcium carbonate load of the leaves, demonstrating a direct link between structural parameters, ΩAr and carbonate deposition. There was a direct relationship between ΩAr, influenced directly by meadow LAI, and CaCO3 content of the leaves. Therefore, calcifying organisms, e.g. epiphytes with carbonate skeletons, might benefit from the modification of the carbonate system by the meadow. The meadow might be capable of providing refugia for calcifiers by increasing pH and ΩAr through metabolic activity. There is, however, concern for the ability of seagrasses to provide this refugia function in the future. The predicted decline of seagrass meadows may alter the scope for alteration of pH within a seagrass meadow and in the water column above the meadow, particularly if shoot density and biomass decline, both strongly linked to LAI. Organisms associated with seagrass communities may therefore suffer from the loss of pH buffering capacity in degraded meadows.

  18. Distribution of seagrasses along the Indian coast

    Digital Repository Service at National Institute of Oceanography (India)

    Jagtap, T.G.

    Seagrass environments, from the main coast of India, Lakshadweep and Andaman Islands, were surveyed for seagrass and marine algal composition. Extensive seagrass meadows and the maximum number of species (seven genera and 12 species) occurred along...

  19. Light availability and temperature, not increased CO2, will structure future meadows of Posidonia oceanica

    KAUST Repository

    Hendriks, Iris E.

    2017-02-15

    We evaluated the photosynthetic performance of Posidonia oceanica during short-term laboratory exposures to ambient and elevated temperatures (24–25°C and 29–30°C) warming and pCO2 (380, 750 and 1000ppm pCO2) under normal and low light conditions (200 and 40μmol photons m−2s−1 respectively). Plant growth was measured at the low light regime and showed a negative response to warming. Light was a critical factor for photosynthetic performance, although we found no evidence of compensation of photosynthetic quantum efficiency in high light. Relative Electron Rate Transport (rETRmax) was higher in plants incubated in high light, but not affected by pCO2 or temperature. The saturation irradiance (Ik) was negatively affected by temperature. We conclude that elevated CO2 does not enhance photosynthetic activity and growth, in the short term for P. oceanica, while temperature has a direct negative effect on growth. Low light availability also negatively affected photosynthetic performance during the short experimental period examined here. Therefore increasing concentrations of CO2 may not compensate for predicted future conditions of warmer water and higher turbidity for seagrass meadows.

  20. Epiphytes modulate Posidonia oceanica photosynthetic production, energetic balance, antioxidant mechanisms and oxidative damage

    Directory of Open Access Journals (Sweden)

    Monya Mendes Costa

    2015-12-01

    Full Text Available Epiphytes impose physical barriers to light penetration into seagrass leaves causing shading, which may decrease the production of oxygen reactive species (ROS, but also constitute a physical aggression that may trigger the production of ROS, leading to oxidative damage. Here we investigate the effects of epiphytes on Posidonia oceanica under both interactive perspectives, light attenuation and oxidative stress. Specifically the role of epiphytes in net photosynthesis, chlorophyll a and b, photoprotection (Violaxanthin+Anteraxanthin+Zeaxanthin cycle, soluble sugar and starch contents, enzymatic (ascorbate peroxidase (APX and dehydroascorbate reductase (DHAR and global (trolox equivalent antioxidant capacity (TEAC and oxygen radical antioxidant capacity (ORAC antioxidant responses, phenolics and oxidative damage (malondialdehyde are tested. Leaves with epiphytes showed higher chlorophyll b and lower content in VAZ cycle carotenoids. Epiphyte shading was the probable reason for the lower VAZ de-epoxidation-ratio of leaves with epiphytes. In spite of being shaded, leaves with epiphytes showed higher antioxidant levels, indicating that epiphytes trigger the production of ROS. Both ORAC and TEAC and also APX and DHAR activities were higher in leaves with epiphytes, indicating that this response was related with its presence. Malondialdehyde concentrations also suggest oxidative damage caused by epiphytes. We conclude that the epiphyte load causes oxidative stress in P. oceanica and the mechanisms to scavenge ROS were not completely effective to avoid cell damage.

  1. CUBESAT-DERIVED DETECTION OF SEAGRASSES USING PLANET IMAGERY FOLLOWING UNMIXING-BASED DENOISING: IS SMALL THE NEXT BIG?

    Directory of Open Access Journals (Sweden)

    D. Traganos

    2017-05-01

    Full Text Available Seagrasses are one of the most productive and widespread yet threatened coastal ecosystems on Earth. Despite their importance, they are declining due to various threats, which are mainly anthropogenic. Lack of data on their distribution hinders any effort to rectify this decline through effective detection, mapping and monitoring. Remote sensing can mitigate this data gap by allowing retrospective quantitative assessment of seagrass beds over large and remote areas. In this paper, we evaluate the quantitative application of Planet high resolution imagery for the detection of seagrasses in the Thermaikos Gulf, NW Aegean Sea, Greece. The low Signal-to-noise Ratio (SNR, which characterizes spectral bands at shorter wavelengths, prompts the application of the Unmixing-based denoising (UBD as a pre-processing step for seagrass detection. A total of 15 spectral-temporal patterns is extracted from a Planet image time series to restore the corrupted blue and green band in the processed Planet image. Subsequently, we implement Lyzenga’s empirical water column correction and Support Vector Machines (SVM to evaluate quantitative benefits of denoising. Denoising aids detection of Posidonia oceanica seagrass species by increasing its producer and user accuracy by 31.7 % and 10.4 %, correspondingly, with a respective increase in its Kappa value from 0.3 to 0.48. In the near future, our objective is to improve accuracies in seagrass detection by applying more sophisticated, analytical water column correction algorithms to Planet imagery, developing time- and cost-effective monitoring of seagrass distribution that will enable in turn the effective management and conservation of these highly valuable and productive ecosystems.

  2. Cubesat-Derived Detection of Seagrasses Using Planet Imagery Following Unmixing-Based Denoising: is Small the Next Big?

    Science.gov (United States)

    Traganos, D.; Cerra, D.; Reinartz, P.

    2017-05-01

    Seagrasses are one of the most productive and widespread yet threatened coastal ecosystems on Earth. Despite their importance, they are declining due to various threats, which are mainly anthropogenic. Lack of data on their distribution hinders any effort to rectify this decline through effective detection, mapping and monitoring. Remote sensing can mitigate this data gap by allowing retrospective quantitative assessment of seagrass beds over large and remote areas. In this paper, we evaluate the quantitative application of Planet high resolution imagery for the detection of seagrasses in the Thermaikos Gulf, NW Aegean Sea, Greece. The low Signal-to-noise Ratio (SNR), which characterizes spectral bands at shorter wavelengths, prompts the application of the Unmixing-based denoising (UBD) as a pre-processing step for seagrass detection. A total of 15 spectral-temporal patterns is extracted from a Planet image time series to restore the corrupted blue and green band in the processed Planet image. Subsequently, we implement Lyzenga's empirical water column correction and Support Vector Machines (SVM) to evaluate quantitative benefits of denoising. Denoising aids detection of Posidonia oceanica seagrass species by increasing its producer and user accuracy by 31.7 % and 10.4 %, correspondingly, with a respective increase in its Kappa value from 0.3 to 0.48. In the near future, our objective is to improve accuracies in seagrass detection by applying more sophisticated, analytical water column correction algorithms to Planet imagery, developing time- and cost-effective monitoring of seagrass distribution that will enable in turn the effective management and conservation of these highly valuable and productive ecosystems.

  3. Impact of ISWEC sea wave energy converter on posidonia oceanica meadows assessed by satellite remote sensing in the coastal areas of Pantelleria island

    Science.gov (United States)

    Borfecchia, Flavio; Micheli, Carla; Belmonte, Alessandro; De Cecco, Luigi; Sannino, Gianmaria; Bracco, Giovanni; Mattiazzo, Giuliana; Vittoria Struglia, Maria

    2016-04-01

    Marine renewable energy extraction plays a key role both in energy security of small islands and in mitigation of climate change, but at the same time poses the important question of monitoring the effects of the interaction of such devices with the marine environment. In this work we present a new methodology, integrating satellite remote sensing techniques with in situ observations and biophysical parameters analysis, for the monitoring and mapping of Posidonia Oceanica (PO) meadows in shallow coastal waters. This methodology has been applied to the coastal area offshore Pantelleria Island (Southern Mediterranean) where the first Italian Inertial Sea Wave Energy Converter (ISWEC) prototype has been recently installed. The prototype, developed by the Polytechnic of Turin consists of a platform 8 meters wide, 15 meters long and 4.5 meters high, moored at about 800 meters from the shore and at 31 m depth. It is characterized by high conversion efficiency, resulting from its adaptability to different wave conditions, and a limited environmental impact due to its mooring innovative method with absence of fixed anchors to the seabed. The island of Pantelleria, is characterized by high transparency of coastal waters and PO meadows ecosystems with still significant levels of biodiversity and specific adaptation to accentuated hydrodynamics of these shores. Although ISWEC is a low-impact mooring inertial system able to ensure a reliable connection to the electric grid with minimal impact on seagrass growing in the seabed, the prototype installation and operation involves an interaction with local PO and seagrass meadows and possible water transparency decreasing. In this view monitoring of local PO ecosystem is mandatory in order to allow the detection of potential stress and damages due to ISWEC related activities and/or other factors. However, monitoring and collection of accurate and repetitive information over large areas of the necessary parameters by means of

  4. Planting Guidelines for Seagrasses.

    Science.gov (United States)

    1980-02-01

    a soil type which is possibly different from the source and could ameliorate possible plant-substrate nutrient interactions . 5. Nutrients. Nutrients...and Knowles (1972) found nitrogen fixed in the rhizosphere of eelgrass. McRoy and Barsdate (1970) reported that eelgrass leaves absorb phosphorus, but...is de- posited in sediments in seagrass meadows, but may be flushed out of the system. Fenchel (1977) reported that microbial decomposition of sea

  5. A survey-based assessment of seagrass status, management and legislation in Europe

    Directory of Open Access Journals (Sweden)

    Carmen B. De Los Santos

    2014-06-01

    agencies are involved and without standardised methodologies in some countries, and the information was said to be unaccessible sometimes. Several attempts of seagrass recovery were reported in Europe (Fig 3, mainly for Zostera spp, although most of them were described as experimental, in early stage to determine their success, or with “poor” or “very poor” success. Although restoration programmes are considered as a feasible solution to seagrass recovery, efforts towards natural restoration potential has been recommended (Cunha et al., 2012. Rating of seagrass management was unequal across European countries (Fig 1. Only the 39% of the countries mentioned the existence of management plans for seagrasses, but in most cases they were not strictly aimed at seagrass ecosystems. In other regions, management plans were under construction or they only included a single seagrass species (e.g. P. oceanica in the Mediterranean Sea. Respondents mentioned a lack of coordination between different administrative levels (national, regional, local dealing with seagrass management. Detailed perceptions about positive interaction with managers were only given by some respondents (Germany and The Netherlands. Other countries only mentioned that interactions were “good”, “positive” and/or “useful” although others described them as “scarce”, “ineffective” or “constrained”, or only exclusive for monitoring issues. Some respondents pointed out that managers, and no scientists, should take the initiative in this kind of interactions, and that the WFD offers an excellent opportunity to improve the scientific-managers interface. Seagrass species and habitats in Europe are subjected to different levels of protection which ranges from international directives and conventions, to national and regional regulations. Within this ample sphere of legislation to protect seagrasses, only a few of them act at a specific level. At the international level, the compiled

  6. Establishing research strategies, methodologies and technologies to link genomics and proteomics to seagrass productivity, community metabolism and ecosystem carbon fluxes

    Directory of Open Access Journals (Sweden)

    Silvia eMazzuca

    2013-03-01

    Full Text Available A complete understanding of the mechanistic basis of marine ecosystem functioning is only possible through integrative and interdisciplinary research. This enables the prediction of change and possibly the mitigation of the consequences of anthropogenic impacts. One major aim of the COST Action ES0609 Seagrasses productivity. From genes to ecosystem management, is the calibration and synthesis of various methods and the development of innovative techniques and protocols for studying seagrass ecosystems.During ten days, twenty researchers representing a range of disciplines (molecular biology, physiology, botany, ecology, oceanography, underwater acoustics gathered at the marine station of STARESO (Corsica to study together the nearby Posidonia oceanica meadow. The Station de Recherches Sous-marine et Océanographiques (STARESO is located in an oligotrophic area classified as "pristine site" where environmental disturbances caused by anthropogenic pressure are exceptionally low. The healthy P. oceanica meadow, that grows in front of the lab, colonizes the sea bottom from the surface to 37 m depth. During the study, genomic and proteomic approaches were integrated with ecophysiological and physical approaches with the aim of understanding changes in seagrass productivity and metabolism at different depths and along daily cycles. In this paper we report details on the approaches utilized and we forecast the potential of the data that will come from this synergistic approach not only for P. oceanica but for seagrasses in general.

  7. Establishing research strategies, methodologies and technologies to link genomics and proteomics to seagrass productivity, community metabolism, and ecosystem carbon fluxes.

    Science.gov (United States)

    Mazzuca, Silvia; Björk, M; Beer, S; Felisberto, P; Gobert, S; Procaccini, G; Runcie, J; Silva, J; Borges, A V; Brunet, C; Buapet, P; Champenois, W; Costa, M M; D'Esposito, D; Gullström, M; Lejeune, P; Lepoint, G; Olivé, I; Rasmusson, L M; Richir, J; Ruocco, M; Serra, I A; Spadafora, A; Santos, Rui

    2013-01-01

    A complete understanding of the mechanistic basis of marine ecosystem functioning is only possible through integrative and interdisciplinary research. This enables the prediction of change and possibly the mitigation of the consequences of anthropogenic impacts. One major aim of the European Cooperation in Science and Technology (COST) Action ES0609 "Seagrasses productivity. From genes to ecosystem management," is the calibration and synthesis of various methods and the development of innovative techniques and protocols for studying seagrass ecosystems. During 10 days, 20 researchers representing a range of disciplines (molecular biology, physiology, botany, ecology, oceanography, and underwater acoustics) gathered at The Station de Recherches Sous-marines et Océanographiques (STARESO, Corsica) to study together the nearby Posidonia oceanica meadow. STARESO is located in an oligotrophic area classified as "pristine site" where environmental disturbances caused by anthropogenic pressure are exceptionally low. The healthy P. oceanica meadow, which grows in front of the research station, colonizes the sea bottom from the surface to 37 m depth. During the study, genomic and proteomic approaches were integrated with ecophysiological and physical approaches with the aim of understanding changes in seagrass productivity and metabolism at different depths and along daily cycles. In this paper we report details on the approaches utilized and we forecast the potential of the data that will come from this synergistic approach not only for P. oceanica but for seagrasses in general.

  8. Clonality in seagrasses, emergent properties and seagrass landscapes

    OpenAIRE

    Kendrick, Gary A.; Duarte, Carlos M.; Marbà, Núria

    2005-01-01

    Seagrasses are clonal monocots that dominate shallow subtidal coastal and estuarine environments worldwide. They are important for their relatively high productivity and their role in coastal sediment stabilization, as habitat and food for invertebrates, fishes, turtles, dugongs and manatees, and as a source for detrital food webs. Seagrasses grow through the iteration of a vegetative ramet, consisting of leaves capable of photosynthesizing attached to a shoot, a portion of rhizome and associ...

  9. Seagrass sediments reveal the long-term deterioration of an estuarine ecosystem

    KAUST Repository

    Serrano, Oscar

    2016-01-28

    © 2016 John Wiley & Sons Ltd. The study of a Posidonia australis sediment archive has provided a record of ecosystem dynamics and processes over the last 600 years in Oyster Harbour (SW Australia). Ecosystem shifts are a widespread phenomenon in coastal areas, and this study identifies baseline conditions and the time-course of ecological change (cycles, trends, resilience and thresholds of ecosystem change) under environmental stress in seagrass-dominated ecosystem. The shifts in the concentrations of chemical elements, carbonates, sediments <0.125 mm and stable carbon isotope signatures (δ13C) of the organic matter were detected between 1850s and 1920s, whereas the shift detected in P concentration occurred several decades later (1960s). The first degradation phase (1850s-1950s) follows the onset of European settlement in Australia and was characterized by a strong increase in sediment accumulation rates and fine-grained particles, driven primarily by enhanced run-off due to land clearance and agriculture in the catchment. About 80% of total seagrass area at Oyster Harbour was lost during the second phase of environmental degradation (1960s until present). The sharp increase in P concentration and the increasing contribution of algae and terrestrial inputs into the sedimentary organic matter pool around 1960s provides compelling evidence of the documented eutrophication of the estuary and the subsequent loss of seagrass meadows. The results presented demonstrate the power of seagrass sedimentary archives to reconstruct the trajectories of anthropogenic pressures on estuarine ecosystem and the associated regime shifts, which can be used to improve the capacity of scientists and environmental managers to understand, predict and better manage ecological change in these ecosystems.

  10. Removal of vanadium(III and molybdenum(V from wastewater using Posidonia oceanica (Tracheophyta biomass.

    Directory of Open Access Journals (Sweden)

    Chiara Pennesi

    Full Text Available The use of dried and re-hydrated biomass of the seagrass Posidonia oceanica was investigated as an alternative and -low-cost biomaterial for removal of vanadium(III and molybdenum(V from wastewaters. Initial characterisation of this biomaterial identified carboxylic groups on the cuticle as potentially responsible for cation sorption, and confirmed the toxic-metal bioaccumulation. The combined effects on biosorption performance of equilibrium pH and metal concentrations were investigated in an ideal single-metal system and in more real-life multicomponent systems. There were either with one metal (vanadium or molybdenum and sodium nitrate, as representative of high ionic strength systems, or with the two metals (vanadium and molybdenum. For the single-metal solutions, the optimum was at pH 3, where a significant proportion of vanadium was removed (ca. 70% while there was ca. 40% adsorption of molybdenum. The data obtained from the more real-life multicomponent systems showed that biosorption of one metal was improved both by the presence of the other metal and by high ionic strength, suggesting a synergistic effect on biosorption rather than competition. There data ware used for the development of a simple multi-metal equilibrium model based on the non-competitive Langmuir approach, which was successfully fitted to experimental data and represents a useful support tool for the prediction of biosorption performance in such real-life systems. Overall, the results suggest that biomass of P. oceanica can be used as an efficient biosorbent for removal of vanadium(III and molybdenum(V from aqueous solutions. This process thus offers an eco-compatible solution for the reuse of the waste material of leaves that accumulate on the beach due to both human activities and to storms at sea.

  11. Submerged Aquatic Vegetation (SAV) - Volusia County Seagrass

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — Aquatic vegetation in Volusia County. DEP SEA_GRASSES This polygon GIS data set represents a compilation of statewide seagrass data from various source agencies and...

  12. Seagrass responses to interacting abiotic stresses

    NARCIS (Netherlands)

    La Nafie, Y.A.

    2016-01-01

    Seagrasses are coastal and marine flowering plants that inhabit thetropical and temperate coastal and marine areas around the globe. They havemany important functions and values, physically, ecologically andeconomically. Physically, seagrass contribute to coastal protection as theyattenuate wave

  13. Can mud (silt and clay) concentration be used to predict soil organic carbon content within seagrass ecosystems?

    KAUST Repository

    Serrano, O.

    2016-01-18

    The emerging field of blue carbon science is seeking cost-effective ways to estimate the organic carbon content of soils that are bound by coastal vegetated ecosystems. Organic carbon (Corg) content in terrestrial soils and marine sediments has been correlated with mud content (i.e. silt and clay), however, empirical tests of this theory are lacking for coastal vegetated ecosystems. Here, we compiled data (n = 1345) on the relationship between Corg and mud (i.e. silt and clay, particle sizes <63 μm) contents in seagrass ecosystems (79 cores) and adjacent bare sediments (21 cores) to address whether mud can be used to predict soil Corg content. We also combined these data with the δ13C signatures of the soil Corg to understand the sources of Corg stores. The results showed that mud is positively correlated with soil Corg content only when the contribution of seagrass-derived Corg to the sedimentary Corg pool is relatively low, such as in small and fast growing meadows of the genera Zostera, Halodule and Halophila, and in bare sediments adjacent to seagrass ecosystems. In large and long-living seagrass meadows of the genera Posidonia and Amphibolis there was a lack of, or poor relationship between mud and soil Corg content, related to a higher contribution of seagrass-derived Corg to the sedimentary Corg pool in these meadows. The relative high soil Corg contents with relatively low mud contents (i.e. mud-Corg saturation) together with significant allochthonous inputs of terrestrial organic matter could overall disrupt the correlation expected between soil Corg and mud contents. This study shows that mud (i.e. silt and clay content) is not a universal proxy for blue carbon content in seagrass ecosystems, and therefore should not be applied generally across all seagrass

  14. Combined Rock-physical Modelling and Seismic Inversion Techniques for Characterisation of the Posidonia Shale Formation

    NARCIS (Netherlands)

    Justiniano, A.; Jaya, M.; Diephuis, G.

    2015-01-01

    The objective of this study is to characterise the Jurassic Posidonia Shale Formation at Block Q16 located in the West Netherlands Basin. The characterisation was carried out through combining rock-physics modelling and seismic inversion techniques. The results show that the Posidonia Shale Formatio

  15. Fine-Scale Cartography of Human Impacts along French Mediterranean Coasts: A Relevant Map for the Management of Marine Ecosystems.

    Directory of Open Access Journals (Sweden)

    Florian Holon

    Full Text Available Ecosystem services provided by oceans and seas support most human needs but are threatened by human activities. Despite existing maps illustrating human impacts on marine ecosystems, information remains either large-scale but rough and insufficient for stakeholders (1 km² grid, lack of data along the coast or fine-scale but fragmentary and heterogeneous in methodology. The objectives of this study are to map and quantify the main pressures exerted on near-coast marine ecosystems, at a large spatial scale though in fine and relevant resolution for managers (one pixel = 20 x 20 m. It focuses on the French Mediterranean coast (1,700 km of coastline including Corsica at a depth of 0 to 80 m. After completing and homogenizing data presently available under GIS on the bathymetry and anthropogenic pressures but also on the seabed nature and ecosystem vulnerability, we provide a fine modeling of the extent and impacts of 10 anthropogenic pressures on marine habitats. The considered pressures are man-made coastline, boat anchoring, aquaculture, urban effluents, industrial effluents, urbanization, agriculture, coastline erosion, coastal population and fishing. A 1:10 000 continuous habitat map is provided considering 11 habitat classes. The marine bottom is mostly covered by three habitats: infralittoral soft bottom, Posidonia oceanica meadows and circalittoral soft bottom. Around two thirds of the bottoms are found within medium and medium high cumulative impact categories. Seagrass meadows are the most impacted habitats. The most important pressures (in area and intensity are urbanization, coastal population, coastal erosion and man-made coastline. We also identified areas in need of a special management interest. This work should contribute to prioritize environmental needs, as well as enhance the development of indicators for the assessment of the ecological status of coastal systems. It could also help better apply and coordinate management measures

  16. Fine-Scale Cartography of Human Impacts along French Mediterranean Coasts: A Relevant Map for the Management of Marine Ecosystems

    Science.gov (United States)

    Holon, Florian; Mouquet, Nicolas; Boissery, Pierre; Bouchoucha, Marc; Delaruelle, Gwenaelle; Tribot, Anne-Sophie; Deter, Julie

    2015-01-01

    Ecosystem services provided by oceans and seas support most human needs but are threatened by human activities. Despite existing maps illustrating human impacts on marine ecosystems, information remains either large-scale but rough and insufficient for stakeholders (1 km² grid, lack of data along the coast) or fine-scale but fragmentary and heterogeneous in methodology. The objectives of this study are to map and quantify the main pressures exerted on near-coast marine ecosystems, at a large spatial scale though in fine and relevant resolution for managers (one pixel = 20 x 20 m). It focuses on the French Mediterranean coast (1,700 km of coastline including Corsica) at a depth of 0 to 80 m. After completing and homogenizing data presently available under GIS on the bathymetry and anthropogenic pressures but also on the seabed nature and ecosystem vulnerability, we provide a fine modeling of the extent and impacts of 10 anthropogenic pressures on marine habitats. The considered pressures are man-made coastline, boat anchoring, aquaculture, urban effluents, industrial effluents, urbanization, agriculture, coastline erosion, coastal population and fishing. A 1:10 000 continuous habitat map is provided considering 11 habitat classes. The marine bottom is mostly covered by three habitats: infralittoral soft bottom, Posidonia oceanica meadows and circalittoral soft bottom. Around two thirds of the bottoms are found within medium and medium high cumulative impact categories. Seagrass meadows are the most impacted habitats. The most important pressures (in area and intensity) are urbanization, coastal population, coastal erosion and man-made coastline. We also identified areas in need of a special management interest. This work should contribute to prioritize environmental needs, as well as enhance the development of indicators for the assessment of the ecological status of coastal systems. It could also help better apply and coordinate management measures at a relevant

  17. Fine-Scale Cartography of Human Impacts along French Mediterranean Coasts: A Relevant Map for the Management of Marine Ecosystems.

    Science.gov (United States)

    Holon, Florian; Mouquet, Nicolas; Boissery, Pierre; Bouchoucha, Marc; Delaruelle, Gwenaelle; Tribot, Anne-Sophie; Deter, Julie

    2015-01-01

    Ecosystem services provided by oceans and seas support most human needs but are threatened by human activities. Despite existing maps illustrating human impacts on marine ecosystems, information remains either large-scale but rough and insufficient for stakeholders (1 km² grid, lack of data along the coast) or fine-scale but fragmentary and heterogeneous in methodology. The objectives of this study are to map and quantify the main pressures exerted on near-coast marine ecosystems, at a large spatial scale though in fine and relevant resolution for managers (one pixel = 20 x 20 m). It focuses on the French Mediterranean coast (1,700 km of coastline including Corsica) at a depth of 0 to 80 m. After completing and homogenizing data presently available under GIS on the bathymetry and anthropogenic pressures but also on the seabed nature and ecosystem vulnerability, we provide a fine modeling of the extent and impacts of 10 anthropogenic pressures on marine habitats. The considered pressures are man-made coastline, boat anchoring, aquaculture, urban effluents, industrial effluents, urbanization, agriculture, coastline erosion, coastal population and fishing. A 1:10 000 continuous habitat map is provided considering 11 habitat classes. The marine bottom is mostly covered by three habitats: infralittoral soft bottom, Posidonia oceanica meadows and circalittoral soft bottom. Around two thirds of the bottoms are found within medium and medium high cumulative impact categories. Seagrass meadows are the most impacted habitats. The most important pressures (in area and intensity) are urbanization, coastal population, coastal erosion and man-made coastline. We also identified areas in need of a special management interest. This work should contribute to prioritize environmental needs, as well as enhance the development of indicators for the assessment of the ecological status of coastal systems. It could also help better apply and coordinate management measures at a relevant

  18. Diel and vertical movements of preflexion fish larvae assemblage associated with Posidonia oceanica beds

    Directory of Open Access Journals (Sweden)

    Yoana del Pilar Ruso

    2006-09-01

    Full Text Available Habitat complexity is a strong determinant of fish assemblage structure. Enhanced food resources and protection from predators are generally considered the main benefits of vegetated areas. We investigated the diel and vertical movements of preflexion fish larvae within and above the leaf canopy of Posidonia oceanica to determine if it acts as an important habitat for larval stage fish. Samples were taken with moored plankton nets during the night and day at two depths (13 and 15 m over five consecutive days in July 2000 in the Marine Protected Area off Tabarca Island (Spain, SW Mediterranean Sea. In total, 353 fish larvae were captured. The most abundant taxa were Sardinella aurita, Sparidae, Engraulis encrasicolus and Gobiidae. Sparidae were more abundant within the leaf canopy during the day but increased in waters 2 m above the canopy at night. In contrast, Sardinella aurita were present throughout the entire water column during both the day and night. We conclude that the P. oceanica leaf canopy is important as a transitional shelter for the early stage larvae of some demersal fish species.

  19. Decreasing seagrass density negatively influences associated fauna.

    Science.gov (United States)

    McCloskey, Rosemary M; Unsworth, Richard K F

    2015-01-01

    Seagrass meadows globally are disappearing at a rapid rate with physical disturbances being one of the major drivers of this habitat loss. Disturbance of seagrass can lead to fragmentation, a reduction in shoot density, canopy height and coverage, and potentially permanent loss of habitat. Despite being such a widespread issue, knowledge of how such small scale change affects the spatial distribution and abundances of motile fauna remains limited. The present study investigated fish and macro faunal community response patterns to a range of habitat variables (shoot length, cover and density), including individual species habitat preferences within a disturbed and patchy intertidal seagrass meadow. Multivariate analysis showed a measurable effect of variable seagrass cover on the abundance and distribution of the fauna, with species specific preferences to both high and low seagrass cover seagrass. The faunal community composition varied significantly with increasing/decreasing cover. The faunal species composition of low cover seagrass was more similar to sandy control plots than to higher cover seagrass. Shannon Wiener Diversity (H') and species richness was significantly higher in high cover seagrass than in low cover seagrass, indicating increasing habitat value as density increases. The results of this study underline how the impacts of small scale disturbances from factors such as anchor damage, boat moorings and intertidal vehicle use on seagrass meadows that reduce shoot density and cover can impact upon associated fauna. These impacts have negative consequences for the delivery of ecosystem services such as the provision of nursery habitat.

  20. Seagrasses - The forgotton marine habitat

    Digital Repository Service at National Institute of Oceanography (India)

    Jagtap, T.G.; Rodrigues, R.S.

    constitute the seagrass flora of Goa, and their patches occur in the lower intertidal and shallow littoral, polyhaline (18-30 ppt) zones. The prominent beds in Goa exist along Mandovi and Terekhol estuaries, and Chapora Bay. These habitats in the country have...

  1. Extinction risk assessment of the world’s seagrass species

    Digital Repository Service at National Institute of Oceanography (India)

    Short, F.T.; Polidoro, B.; Livingstone, S.R.; Carpenter, K.E.; Bandeira, S.; Bujang, J.S.; Calumpong, H.P.; Carruthers, T.J.B.; Coles, R.G.; Dennison, W.C.; Erftemeijer, P.L.A.; Fortes, M.D.; Freeman, A.S.; Jagtap, T.G.; Kamal, A.H.M.; Kendrick, G.A.; Kenworthy, W.J.; LaNafie, Y.A.; Nasution, I.M.; Orth, R.J.; Prathep, A.; Sanciangco, J.C.; Tussenbroek, B.V.; Vergara, S.G.; Waycott, M.; Zieman, J.C.

    loss and degradation of seagrass biodiversity will have serious repercussions for marine biodiversity and the human populations that depend upon the resources and ecosystem services that seagrasses provide....

  2. Carbon sequestration processes in tropical seagrass beds

    OpenAIRE

    Lyimo, Liberatus Dominick

    2016-01-01

    Seagrass meadows may play a substantial role in climate change mitigation as they are capable to sequester and store substantial amounts of anthropogenic carbon in plant biomass and, more importantly, in their underlying sediments. In this PhD thesis, the carbon-burial potential was assessed by quantifying the amount of organic carbon stored in different seagrass meadows, each dominated by one of the four major seagrass species in the Western Indian Ocean region. Impacts of anthropogenic dist...

  3. Ecological characteristics of the invasive pufferfish Lagocephalus sceleratus (Gmelin, 1789 in the eastern Mediterranean Sea – a case study from Rhodes

    Directory of Open Access Journals (Sweden)

    S. KALOGIROU

    2013-04-01

    Full Text Available In this study, the ecological and societal impact of the invasive pufferfish Lagocephalus sceleratus on coastal habitats of an area of the eastern Mediterranean Sea (Rhodes Island was investigated. Seasonal quantitative samplings in two common coastal habitats were used to investigate habitat use of different life-stages. Sandy areas were found to be highly important for the early life stages of L. sceleratus. In contrast, Posidonia oceanica habitats were mainly preferred by larger (> 29 cm reproductive adults, not exceeding 64 cm. Lagocephalus sceleratus was found to feed on invertebrates and fish while size classification revealed a tendency for a diet shift with increased size. During early life stages, L. sceleratus inhabits sandy bottoms where it feeds on various invertebrates. The predominant molluscan species found in the diet of larger (> 20 cm L. sceleratus individuals were the economically important Sepia officinalis and Octopus vulgaris. The size at which 50% of individuals reach maturity was estimated to 19 cm. With increased size, habitat shift to seagrass meadows most possibly occurs to meet both the increased demand in prey availability and requirement of appropriate spawning ground. Condition factor of L. sceleratus showed significantly higher values during summer than all other seasons and this was attributed to spawning season and increase in feeding. Societal impacts were alarming due to increased public attention concerning its lethal effects (presence of tetrodotoxin, if consumed. Its high abundance in the coastal fish communities of the studied area combined with ecological and societal impacts, clearly classify L. sceleratus a pest for fisheries and potential threat for biodiversity.

  4. Ecological characteristics of the invasive pufferfish Lagocephalus sceleratus (Gmelin, 1789 in the eastern Mediterranean Sea – a case study from Rhodes

    Directory of Open Access Journals (Sweden)

    S. KALOGIROU

    2013-07-01

    Full Text Available In this study, the ecological and societal impact of the invasive pufferfish Lagocephalus sceleratus on coastal habitats of an area of the eastern Mediterranean Sea (Rhodes Island was investigated. Seasonal quantitative samplings in two common coastal habitats were used to investigate habitat use of different life-stages. Sandy areas were found to be highly important for the early life stages of L. sceleratus. In contrast, Posidonia oceanica habitats were mainly preferred by larger (> 29 cm reproductive adults, not exceeding 64 cm. Lagocephalus sceleratus was found to feed on invertebrates and fish while size classification revealed a tendency for a diet shift with increased size. During early life stages, L. sceleratus inhabits sandy bottoms where it feeds on various invertebrates. The predominant molluscan species found in the diet of larger (> 20 cm L. sceleratus individuals were the economically important Sepia officinalis and Octopus vulgaris. The size at which 50% of individuals reach maturity was estimated to 19 cm. With increased size, habitat shift to seagrass meadows most possibly occurs to meet both the increased demand in prey availability and requirement of appropriate spawning ground. Condition factor of L. sceleratus showed significantly higher values during summer than all other seasons and this was attributed to spawning season and increase in feeding. Societal impacts were alarming due to increased public attention concerning its lethal effects (presence of tetrodotoxin, if consumed. Its high abundance in the coastal fish communities of the studied area combined with ecological and societal impacts, clearly classify L. sceleratus a pest for fisheries and potential threat for biodiversity.

  5. Nitrogen fixation in Red Sea seagrass meadows

    KAUST Repository

    Abdallah, Malak

    2017-05-01

    Seagrasses are key coastal ecosystems, providing many ecosystem services. Seagrasses increase biodiversity as they provide habitat for a large set of organisms. In addition, their structure provides hiding places to avoid predation. Seagrasses can grow in shallow marine coastal areas, but several factors regulate their growth and distribution. Seagrasses can uptake different kinds of organic and inorganic nutrients through their leaves and roots. Nitrogen and phosphorous are the most important nutrients for seagrass growth. Biological nitrogen fixation is the conversion of atmospheric nitrogen into ammonia by diazotrophic bacteria. This process provides a significant source of nitrogen for seagrass growth. The nitrogen fixation is controlled by the nif genes which are found in diazotrophs. The main goal of the project is to measure nitrogen fixation rates on seagrass sediments, in order to compare among various seagrass species from the Red Sea. Moreover, we will compare the fixing rates of the Vegetated areas with the bare sediments. This project will help to ascertain the role of nitrogen fixing bacteria in the development of seagrass meadows.

  6. Dr. Zompo : an online data repository for Zostera marina and Posidonia oceanica ESTs

    NARCIS (Netherlands)

    Wissler, L.; Dattolo, E.; Moore, A. D.; Reusch, T. B. H.; Olsen, J. L.; Migliaccio, M.; Bornberg-Bauer, E.; Procaccini, G.

    2009-01-01

    As ecosystem engineers, seagrasses are angiosperms of paramount ecological importance in shallow shoreline habitats around the globe. Furthermore, the ancestors of independent seagrass lineages have secondarily returned into the sea in separate, independent evolutionary events. Thus, understanding t

  7. The movement ecology of seagrasses.

    Science.gov (United States)

    McMahon, Kathryn; van Dijk, Kor-Jent; Ruiz-Montoya, Leonardo; Kendrick, Gary A; Krauss, Siegfried L; Waycott, Michelle; Verduin, Jennifer; Lowe, Ryan; Statton, John; Brown, Eloise; Duarte, Carlos

    2014-11-22

    A movement ecology framework is applied to enhance our understanding of the causes, mechanisms and consequences of movement in seagrasses: marine, clonal, flowering plants. Four life-history stages of seagrasses can move: pollen, sexual propagules, vegetative fragments and the spread of individuals through clonal growth. Movement occurs on the water surface, in the water column, on or in the sediment, via animal vectors and through spreading clones. A capacity for long-distance dispersal and demographic connectivity over multiple timeframes is the novel feature of the movement ecology of seagrasses with significant evolutionary and ecological consequences. The space-time movement footprint of different life-history stages varies. For example, the distance moved by reproductive propagules and vegetative expansion via clonal growth is similar, but the timescales range exponentially, from hours to months or centuries to millennia, respectively. Consequently, environmental factors and key traits that interact to influence movement also operate on vastly different spatial and temporal scales. Six key future research areas have been identified.

  8. Laboratory investigation of the acoustic response of seagrass tissue in the frequency band 0.5-2.5 kHz.

    Science.gov (United States)

    Wilson, Preston S; Dunton, Kenneth H

    2009-04-01

    Previous in situ investigations of seagrass have revealed acoustic phenomena that depend on plant density, tissue gas content, and free bubbles produced by photosynthetic activity, but corresponding predictive models that could be used to optimize acoustic remote sensing, shallow water sonar, and mine hunting applications have not appeared. To begin to address this deficiency, low frequency (0.5-2.5 kHz) acoustic laboratory experiments were conducted on three freshly collected Texas Gulf Coast seagrass species. A one-dimensional acoustic resonator technique was used to assess the biomass and effective acoustic properties of the leaves and rhizomes of Thalassia testudinum (turtle grass), Syringodium filiforme (manatee grass), and Halodule wrightii (shoal grass). Independent biomass and gas content estimates were obtained via microscopic cross-section imagery. The acoustic results were compared to model predictions based on Wood's equation for a two-phase medium. The effective sound speed in the plant-filled resonator was strongly dependent on plant biomass, but the Wood's equation model (based on tissue gas content alone) could not predict the effective sound speed for the low irradiance conditions of the experiment, in which no free bubbles were generated by photosynthesis. The results corroborate previously published results obtained in situ for another seagrass species, Posidonia oceanica.

  9. Variability of sedimentary organic carbon in patchy seagrass landscapes.

    Science.gov (United States)

    Ricart, Aurora M; York, Paul H; Rasheed, Michael A; Pérez, Marta; Romero, Javier; Bryant, Catherine V; Macreadie, Peter I

    2015-11-15

    Seagrass ecosystems, considered among the most efficient carbon sinks worldwide, encompass a wide variety of spatial configurations in the coastal landscape. Here we evaluated the influence of the spatial configuration of seagrass meadows at small scales (metres) on carbon storage in seagrass sediments. We intensively sampled carbon stocks and other geochemical properties (δ(13)C, particle size, depositional fluxes) across seagrass-sand edges in a Zostera muelleri patchy seagrass landscape. Carbon stocks were significantly higher (ca. 20%) inside seagrass patches than at seagrass-sand edges and bare sediments. Deposition was similar among all positions and most of the carbon was from allochthonous sources. Patch level attributes (e.g. edge distance) represent important determinants of the spatial heterogeneity of carbon stocks within seagrass ecosystems. Our findings indicate that carbon stocks of seagrass areas have likely been overestimated by not considering the influence of meadow landscapes, and have important relevance for the design of seagrass carbon stock assessments.

  10. A reassessment of the use of Posidonia oceanica and Mytilus galloprovincialis to biomonitor the coastal pollution of trace elements: New tools and tips.

    Science.gov (United States)

    Richir, J; Gobert, S

    2014-12-15

    The present study gives a summary using state-of-the-art technology to monitor Posidonia oceanica and Mytilus galloprovincialis as bioindicators of the pollution of the Mediterranean littoral with trace elements (TEs), and discusses their complementarity and specificities in terms of TE bioaccumulation. Furthermore, this study presents two complementary indices, the Trace Element Spatial Variation Index (TESVI) and the Trace Element Pollution Index (TEPI): these indices were shown to be relevant monitoring tools since they led to the ordering of TEs according to the overall spatial variability of their environmental levels (TESVI) and to the relevant comparison of the global TE pollution between monitored sites (TEPI). In addition, this study also discusses some underestimated aspects of P. oceanica and M. galloprovincialis bioaccumulation behaviour, with regard to their life style and ecophysiology. It finally points out the necessity of developing consensual protocols between monitoring surveys in order to publish reliable and comparable results.

  11. Nitrogen dynamics in Posidonia oceanica cuttings: implications for transplantation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lepoint, Gilles; Vangeluwe, Denis; Eisinger, Michael; Paster, Markus; Treeck, Peter van; Bouquegneau, Jean-Marie; Gobert, Sylvie

    2004-03-01

    A {sup 15}N tracer study was performed during an experimental transplantation trial of natural Posidonia oceanica cuttings. The experiment was done in situ at 17 m depth in the Revellata Bay (Calvi, NW Corsica, France). Despite high survival rates of transplants (>90%) after one year, the weight and the N content of transplants are significantly lower than those of reference plants. In absence of roots, the transplants are not able to meet their N requirement because, leaf uptake is insufficient to replenish the N lost during the natural leaf decay. This could constitute a major cause of long-term failure for transplantation experiments or natural re-colonisation processes. The increase of the {sup 15}N content in the roots shows that the plant re-allocates the nitrogen of one organ (i.e. leaves, rhizomes) to ensure the growth of another (i.e. roots)

  12. Differences in macrofaunal and seagrass assemblages in seagrass beds with and without seaweed farms

    Science.gov (United States)

    Eklöf, J. S.; de la Torre Castro, M.; Adelsköld, L.; Jiddawi, N. S.; Kautsky, N.

    2005-05-01

    Since it was introduced to Zanzibar (Tanzania), seaweed farming has significantly contributed to local, socio-economic development. However, several investigations have shown impacts on the coastal environment near where the farms are located. As many seaweed farms are located on seagrass beds, there is a risk that seaweed farming could affect seagrass beds, and thereby disturb important ecosystem functions and the flow of ecological goods and services. This study compares characteristics of macrophytes (focusing on seagrasses), benthic macrofauna and sediment in seagrass beds, with and without seaweed farms, and a sand bank without vegetation in Chwaka Bay, Zanzibar. The results showed that seagrass beds underneath seaweed farms generally had less seagrass and macroalgae, finer sediment, lower sediment organic matter content and a reduced abundance and biomass of macrofauna, than seagrass beds without seaweed farms. Further, the macrofaunal community structure in seaweed farms showed more similarities to that on the sand bank than in the unfarmed seagrass beds. Most of the dissimilarity was attributable to Lucinidae (suspension-feeding bivalves), which were almost absent in the seaweed farms, resulting in the large difference in biomass between the seaweed farms and the unfarmed seagrass beds. When interpreted together with information from farmers, the observed pattern is believed to be caused by the seaweed farming activities. This indicates that more research is needed to establish the effects of seaweed farming on seagrass beds, and that more attention should be given to the location of farms and the choice of farming methods.

  13. The Suez Canal as a habitat and pathway for marine algae and seagrasses

    Science.gov (United States)

    Aleem, A. A.

    The Suez Canal supports a diversified benthic algal flora; 133 species of benthic algae are now known from the Canal, as compared with only 24 in 1924. The vertical and horizontal distribution of algae is considered in relation to hydrographic factors. The algae display zonation and 3-4 algal belts are distinguished on the Canal banks on buoys and pier supports. Associated fauna include Balanus amphitrite and Brachidontes variabilis, together with various hydroids, sponges, ascidians, asteroids, ophiuroids and crustaceans. Merceriella enigmatica thrives well in brackish water habitats. The algal flora in the Bitter Lakes resembles that in the Red Sea. The number of Red Sea species decreases from Suez to Port Said in the littoral zone. On the other hand, bottom algae predominantly belong to Red Sea flora. Thirty of the species of algae found belong to the Indo-Pacific flora; half of these are new records to the Canal. Several of these Indo-Pacific algae have recently become established in the Eastern Mediterranean, whereas only two of the Mediterranean macro-algal flora (viz. Caulerpa prolifera and Halopteris scoparia) have been found in the Gulf of Suez. Two seagrasses, Halopia ovalis and Thalassia hemprichii, are recorded for the first time in the Canal. Only Halophila stipulacea has found its way into the Mediterranean via the Suez Canal, but none of the Mediterranean seagrasses is found either in the Canal or in the Red Sea.

  14. Overview on seagrasses and related research in China

    Science.gov (United States)

    Shi, Yajun; Fan, Hangqing; Cui, Xiaojian; Pan, Lianghao; Li, Sen; Song, Xiukai

    2010-03-01

    Seagrass research in China is still in its infancy. Even though there has been progress recently, there is still a great deal of research needed to gain a better understanding of seagrass. In this article we review and discuss the advances in seagrass research in China from two aspects: (1) seagrass species and their distribution; (2) seagrass research in China, including studies on their taxonomy, ecology, photosynthesis, applications in aquaculture, salt-tolerance mechanisms and other research topics. A total of 18 seagrass species belonging to 8 genera are distributed in nine provinces and regions in China (including Hong Kong and Taiwan), as well as the Xisha and Nansha Archipelagos. They can be divided into two groups: a North China Group and a South China Group. Based on the seagrass distribution, the Chinese mainland coast can be divided into three sections: North China Seagrass Coast, Middle China Seagrass Coast, and South China Seagrass Coast. Ecological studies include research on seagrass communities, nutrient cycling in seagrass ecosystems, genetic diversity, pollution ecology and research in the key regions of Shandong, Guangdong, Guangxi, and Hainan. Seagrass species and their locations, community structure, ecological evaluation, epiphytes, ecological functions and threats in the key regions are also summarized. Other studies have focused on remote sensing of seagrass, threatened seagrass species of China, and pollen morphology of Halophila ovalis.

  15. Seagrass ecosystems in the Western Indian Ocean.

    Science.gov (United States)

    Gullström, Martin; de la Torre Castro, Maricela; Bandeira, Salomão; Björk, Mats; Dahlberg, Mattis; Kautsky, Nils; Rönnbäck, Patrik; Ohman, Marcus C

    2002-12-01

    Seagrasses are marine angiosperms widely distributed in both tropical and temperate coastal waters creating one of the most productive aquatic ecosystems on earth. In the Western Indian Ocean (WIO) region, with its 13 reported seagrass species, these ecosystems cover wide areas of near-shore soft bottoms through the 12 000 km coastline. Seagrass beds are found intertidally as well as subtidally, sometimes down to about 40 m, and do often occur in close connection to coral reefs and mangroves. Due to the high primary production and a complex habitat structure, seagrass beds support a variety of benthic, demersal and pelagic organisms. Many fish and shellfish species, including those of commercial interest, are attracted to seagrass habitats for foraging and shelter, especially during their juvenile life stages. Examples of abundant and widespread fish species associated to seagrass beds in the WIO belong to the families Apogonidae, Blenniidae, Centriscidae, Gerreidae, Gobiidae, Labridae, Lethrinidae Lutjanidae, Monacanthidae, Scaridae, Scorpaenidae, Siganidae, Syngnathidae and Teraponidae. Consequently, seagrass ecosystems in the WIO are valuable resources for fisheries at both local and regional scales. Still, seagrass research in the WIO is scarce compared to other regions and it is mainly focusing on botanic diversity and ecology. This article reviews the research status of seagrass beds in the WIO with particular emphasis on fish and fisheries. Most research on this topic has been conducted along the East African coast, i.e. in Kenya, Tanzania, Mozambique and eastern South Africa, while less research was carried out in Somalia and the Island States of the WIO (Seychelles, Comoros, Reunion (France), Mauritius and Madagascar). Published papers on seagrass fish ecology in the region are few and mainly descriptive. Hence, there is a need of more scientific knowledge in the form of describing patterns and processes through both field and experimental work

  16. Quantifying Seagrass Light Requirements Using an Algorithm to Spatially Resolve Depth of Colonization-Conf Abstract

    Science.gov (United States)

    Depth of colonization (Zc) is a useful seagrass growth metric that describes seagrass response to light attenuation. Similarly, percent surface irradiance (% SI) at Zc is a measure of seagrass light requirements with applications in seagrass ecology and management. Methods for ...

  17. Evaluation of a temporal trend heavy metals contamination in Posidonia oceanica (L.) Delile, (1813) along the western coastline of Sicily (Italy).

    Science.gov (United States)

    Copat, Chiara; Maggiore, Riccardo; Arena, Giovanni; Lanzafame, Stanislao; Fallico, Roberto; Sciacca, Salvatore; Ferrante, Margherita

    2012-01-01

    The use of biological species in the monitoring of marine environmental quality allows the evaluation of biologically available levels of contaminants in the ecosystem and the effects of contaminants on living organisms. The seagrass Posidonia oceanica is a useful bioindicator because through the lepidochronology technique it is possible to obtain a historical contamination trend of a given area. This study aims to assess the temporal trend contamination by heavy metal investigations on dead sheaths of 100 samples of P. oceanica collected in the Protected Marine Area of "Plemmirio" (Sicily) and in the Siracusa bay. Important results were obtained because data show a significant negative temporal trend for the metals analysed especially for As, Co, Cr, Hg, Pb, Se, U and V that in the past had higher concentrations, with a stronger contamination in the Plemmirio area, the site much more exposed to the pollution of the nearby petrochemical complex. This study confirms the relevance of the use of P. oceanica as a biological indicator of metal contamination in coastal ecosystems. Thus the usefulness of P. oceanica as a tracer of spatial metal contamination and as a good tool for water quality evaluation is reinforced.

  18. Seagrass meadows in a globally changing environment.

    Science.gov (United States)

    Unsworth, Richard K F; van Keulen, Mike; Coles, Rob G

    2014-06-30

    Seagrass meadows are valuable ecosystem service providers that are now being lost globally at an unprecedented rate, with water quality and other localised stressors putting their future viability in doubt. It is therefore critical that we learn more about the interactions between seagrass meadows and future environmental change in the anthropocene. This needs to be with particular reference to the consequences of poor water quality on ecosystem resilience and the effects of change on trophic interactions within the food web. Understanding and predicting the response of seagrass meadows to future environmental change requires an understanding of the natural long-term drivers of change and how these are currently influenced by anthropogenic stress. Conservation management of coastal and marine ecosystems now and in the future requires increased knowledge of how seagrass meadows respond to environmental change, and how they can be managed to be resilient to these changes. Finding solutions to such issues also requires recognising people as part of the social-ecological system. This special issue aims to further enhance this knowledge by bringing together global expertise across this field. The special issues considers issues such as ecosystem service delivery of seagrass meadows, the drivers of long-term seagrass change and the socio-economic consequences of environmental change to seagrass.

  19. Preparation and characterisation of raw chars and physically activated carbons derived from marine Posidonia oceanica (L.) fibres

    Energy Technology Data Exchange (ETDEWEB)

    Ncibi, M.C., E-mail: ncibi_mc@yahoo.com [Laboratoire de chimie, Institut Superieur Agronomique, Chott Meriem 4042, Sousse (Tunisia); Unite de Recherche ' Chimie Appliquee et Environnement' , EPAM Sousse 4000 (Tunisia); Laboratoire COVACHIMM, EA 3592 Universite des Antilles et de la Guyane, BP 250, 97157 Pointe a Pitre Cedex, Guadeloupe (France); Jeanne-Rose, V. [Laboratoire COVACHIMM, EA 3592 Universite des Antilles et de la Guyane, BP 250, 97157 Pointe a Pitre Cedex, Guadeloupe (France); Mahjoub, B. [Laboratoire de chimie, Institut Superieur Agronomique, Chott Meriem 4042, Sousse (Tunisia); Unite de Recherche ' Chimie Appliquee et Environnement' , EPAM Sousse 4000 (Tunisia); Jean-Marius, C. [Laboratoire COVACHIMM, EA 3592 Universite des Antilles et de la Guyane, BP 250, 97157 Pointe a Pitre Cedex, Guadeloupe (France); Lambert, J.; Ehrhardt, J.J. [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement, UMR 7564 CNRS, Universites de Nancy, 405, rue de Vandoeuvre, F 56600 Villers-les-Nancy cedex (France); Bercion, Y. [Groupe de Technologie des Surfaces et Interfaces (GTSI), EA 2432, Faculte des Sciences Exactes et Naturelles, Universite des Antilles et de la Guyane, BP 250, 97157 Pointe a Pitre Cedex, Guadeloupe (France); Seffen, M. [Laboratoire de chimie, Institut Superieur Agronomique, Chott Meriem 4042, Sousse (Tunisia); Unite de Recherche ' Chimie Appliquee et Environnement' , EPAM Sousse 4000 (Tunisia); Gaspard, S. [Laboratoire COVACHIMM, EA 3592 Universite des Antilles et de la Guyane, BP 250, 97157 Pointe a Pitre Cedex, Guadeloupe (France)

    2009-06-15

    Industrial valorisation of low cost and renewable biomass as raw precursor of activated carbon for environmental applications is an interesting alternative to costly commercial activated carbons. In this study, the possible use of Mediterranean, Posidonia oceanica fibrous biomass, as a precursor for chars and physically activated carbons, is investigated. Firstly, the raw marine material was chemically and biochemically characterised throughout dry-basis elemental, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis. Then, several P. oceanica chars were prepared and characterised under different pyrolysis times and temperatures. In addition, physically activated carbons (PACs) were produced via water steam flow under various activation periods. The results showed that the pyrolysis induces the creation of pores at different levels with respect to the involved temperature. Thereafter, the physical activation tends to enhance the development of the porous structure. In that issue, the performed Brunauer-Emmett-Teller (BET) and Barrett-Joiner-Halenda (BJH) analysis revealed that the prepared PACs have a mainly mesoporous inner morphology with a varying fraction of micropores.

  20. Seagrass sediments as a global carbon sink: Isotopic constraints

    Science.gov (United States)

    Kennedy, Hilary; Beggins, Jeff; Duarte, Carlos M.; Fourqurean, James W.; Holmer, Marianne; Marbã, Núria; Middelburg, Jack J.

    2010-12-01

    Seagrass meadows are highly productive habitats found along many of the world's coastline, providing important services that support the overall functioning of the coastal zone. The organic carbon that accumulates in seagrass meadows is derived not only from seagrass production but from the trapping of other particles, as the seagrass canopies facilitate sedimentation and reduce resuspension. Here we provide a comprehensive synthesis of the available data to obtain a better understanding of the relative contribution of seagrass and other possible sources of organic matter that accumulate in the sediments of seagrass meadows. The data set includes 219 paired analyses of the carbon isotopic composition of seagrass leaves and sediments from 207 seagrass sites at 88 locations worldwide. Using a three source mixing model and literature values for putative sources, we calculate that the average proportional contribution of seagrass to the surface sediment organic carbon pool is ˜50%. When using the best available estimates of carbon burial rates in seagrass meadows, our data indicate that between 41 and 66 gC m-2 yr-1 originates from seagrass production. Using our global average for allochthonous carbon trapped in seagrass sediments together with a recent estimate of global average net community production, we estimate that carbon burial in seagrass meadows is between 48 and 112 Tg yr-1, showing that seagrass meadows are natural hot spots for carbon sequestration.

  1. Export from Seagrass Meadows Contributes to Marine Carbon Sequestration

    KAUST Repository

    Duarte, Carlos M.

    2017-01-17

    Seagrasses export a substantial portion of their primary production, both in particulate and dissolved organic form, but the fate of this export production remains unaccounted for in terms of seagrass carbon sequestration. Here we review available evidence on the fate of seagrass carbon export to conclude that this represents a significant contribution to carbon sequestration, both in sediments outside seagrass meadows and in the deep sea. The evidence presented implies that the contribution of seagrass meadows to carbon sequestration has been underestimated by only including carbon burial within seagrass sediments.

  2. EPA Seagrass Restoration 1994-1995

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Study compared nekton densities and community composition in a natural mixed seagrass bed dominated by Halodule wrightii (shoalgrass) with those found in three...

  3. Settlement pattern of Posidonia oceanica epibionts along a gradient of ocean acidification: an approach with mimics

    Directory of Open Access Journals (Sweden)

    L. DONNARUMMA

    2014-02-01

    Full Text Available Effects of ocean acidification (OA on the colonization/settlement pattern of the epibiont community of the leaves and rhizomesof the Mediterranean seagrass,Posidoniaoceanica, have been studied at volcanic CO2vents off Ischia (Italy, using “mimics”as artificial substrates. The experiments were conducted in shallowPosidoniastands (2-3 m depth, in three stations on the northand three on the south sides of the study area, distributed along a pH gradient. At each station, 4 rhizome mimics and 6 artificialleaves were collected every three months (Sept 2009-Sept 2010. The epibionts on both leaf and rhizome mimics showed clearchanges along the pH gradient; coralline algae and calcareous invertebrates (bryozoans, serpulid polychaetes and barnacles weredominant at control stations but progressively disappeared at the most acidified stations. In these extremely low pH sites theassemblage was dominated by filamentous algae and non calcareous taxa such as hydroids and tunicates. Settlement pattern onthe artificial leaves and rhizome mimics over time showed a consistent distribution pattern along the pH gradient and highlightedthe peak of recruitment of the various organisms in different periods according to their life history.Posidoniamimics at theacidified station showed a poor and very simplified assemblage where calcifying epibionts seemed less competitive for space. Thisprofound difference in epiphyte communities in low pH conditions suggests cascading effects on the food web of the meadow and,consequently, on the functioning of the system

  4. Settlement pattern of Posidonia oceanica epibionts along a gradient of ocean acidification: an approach with mimics

    Directory of Open Access Journals (Sweden)

    L. DONNARUMMA

    2014-09-01

    Full Text Available Effects of ocean acidification (OA on the colonization/settlement pattern of the epibiont community of the leaves and rhizomesof the Mediterranean seagrass,Posidoniaoceanica, have been studied at volcanic CO2vents off Ischia (Italy, using “mimics”as artificial substrates. The experiments were conducted in shallowPosidoniastands (2-3 m depth, in three stations on the northand three on the south sides of the study area, distributed along a pH gradient. At each station, 4 rhizome mimics and 6 artificialleaves were collected every three months (Sept 2009-Sept 2010. The epibionts on both leaf and rhizome mimics showed clearchanges along the pH gradient; coralline algae and calcareous invertebrates (bryozoans, serpulid polychaetes and barnacles weredominant at control stations but progressively disappeared at the most acidified stations. In these extremely low pH sites theassemblage was dominated by filamentous algae and non calcareous taxa such as hydroids and tunicates. Settlement pattern onthe artificial leaves and rhizome mimics over time showed a consistent distribution pattern along the pH gradient and highlightedthe peak of recruitment of the various organisms in different periods according to their life history.Posidoniamimics at theacidified station showed a poor and very simplified assemblage where calcifying epibionts seemed less competitive for space. Thisprofound difference in epiphyte communities in low pH conditions suggests cascading effects on the food web of the meadow and,consequently, on the functioning of the system

  5. Automatic seagrass pattern identification on sonar images

    Science.gov (United States)

    Rahnemoonfar, Maryam; Rahman, Abdullah

    2016-05-01

    Natural and human-induced disturbances are resulting in degradation and loss of seagrass. Freshwater flooding, severe meteorological events and invasive species are among the major natural disturbances. Human-induced disturbances are mainly due to boat propeller scars in the shallow seagrass meadows and anchor scars in the deeper areas. Therefore, there is a vital need to map seagrass ecosystems in order to determine worldwide abundance and distribution. Currently there is no established method for mapping the pothole or scars in seagrass. One of the most precise sensors to map the seagrass disturbance is side scan sonar. Here we propose an automatic method which detects seagrass potholes in sonar images. Side scan sonar images are notorious for having speckle noise and uneven illumination across the image. Moreover, disturbance presents complex patterns where most segmentation techniques will fail. In this paper, by applying mathematical morphology technique and calculating the local standard deviation of the image, the images were enhanced and the pothole patterns were identified. The proposed method was applied on sonar images taken from Laguna Madre in Texas. Experimental results show the effectiveness of the proposed method.

  6. Changes in seagrass species composition in northwestern Gulf of Mexico estuaries: effects on associated seagrass fauna.

    Science.gov (United States)

    Ray, Brandon R; Johnson, Matthew W; Cammarata, Kirk; Smee, Delbert L

    2014-01-01

    The objective of this study was to measure the communities associated with different seagrass species to predict how shifts in seagrass species composition may affect associated fauna. In the northwestern Gulf of Mexico, coverage of the historically dominant shoal grass (Halodule wrightii) is decreasing, while coverage of manatee grass (Syringodium filiforme) and turtle grass (Thalassia testudinum) is increasing. We conducted a survey of fishes, crabs, and shrimp in monospecific beds of shoal, manatee, and turtle grass habitats of South Texas, USA to assess how changes in sea grass species composition would affect associated fauna. We measured seagrass parameters including shoot density, above ground biomass, epiphyte type, and epiphyte abundance to investigate relationships between faunal abundance and these seagrass parameters. We observed significant differences in communities among three seagrass species, even though these organisms are highly motile and could easily travel among the different seagrasses. Results showed species specific relationships among several different characteristics of the seagrass community and individual species abundance. More work is needed to discern the drivers of the complex relationships between individual seagrass species and their associated fauna.

  7. Changes in seagrass species composition in northwestern Gulf of Mexico estuaries: effects on associated seagrass fauna.

    Directory of Open Access Journals (Sweden)

    Brandon R Ray

    Full Text Available The objective of this study was to measure the communities associated with different seagrass species to predict how shifts in seagrass species composition may affect associated fauna. In the northwestern Gulf of Mexico, coverage of the historically dominant shoal grass (Halodule wrightii is decreasing, while coverage of manatee grass (Syringodium filiforme and turtle grass (Thalassia testudinum is increasing. We conducted a survey of fishes, crabs, and shrimp in monospecific beds of shoal, manatee, and turtle grass habitats of South Texas, USA to assess how changes in sea grass species composition would affect associated fauna. We measured seagrass parameters including shoot density, above ground biomass, epiphyte type, and epiphyte abundance to investigate relationships between faunal abundance and these seagrass parameters. We observed significant differences in communities among three seagrass species, even though these organisms are highly motile and could easily travel among the different seagrasses. Results showed species specific relationships among several different characteristics of the seagrass community and individual species abundance. More work is needed to discern the drivers of the complex relationships between individual seagrass species and their associated fauna.

  8. Assessing diversity and phytoremediation potential of seagrass in tropical region

    Science.gov (United States)

    Seagrass ecosystem is one of the most important resources in the coastal areas. Seagrasses support and provide habitats for many coastal organisms in tropical region. Seagrasses are specialized marine flowering plants that have adapted to the nearshore environment with heterogeneous landscape struct...

  9. 50 CFR 226.213 - Critical habitat for Johnson's seagrass.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Critical habitat for Johnson's seagrass... Critical habitat for Johnson's seagrass. Critical habitat is designated to include substrate and water in... Johnson's seagrass. (a) A portion of the Indian River, Florida, north of Sebastian Inlet Channel,...

  10. Shale oil potential and thermal maturity of the Lower Toarcian Posidonia Shale in NW Europe

    NARCIS (Netherlands)

    Song, J.; Littke, R.; Weniger, P.; Ostertag-Henning, C.; Nelskamp, S.

    2015-01-01

    A suite of drilling cores and outcrop samples of the Lower Toarcian Posidonia Shale (PS) were collected from multiple locations including the Swabian Alb and Franconian Alb of Southwest-Germany, Runswick Bay of UK and Loon op Zand well (LOZ-1) of the West Netherlands Basin. In order to assess the th

  11. Geomechanical and anisotropic acoustic properties of Lower Jurassic Posidonia Shales from Whitby (UK)

    NARCIS (Netherlands)

    Zhubayev, Alimzhan; Houben, Maartje; Smeulders, David; Barnhoorn, Auke

    2014-01-01

    The Posidonia Shale Formation (PSF) is one of the possible resource shales for unconventional gas in Northern Europe and currently is of great interest to hydrocarbon exploration and production. Due to low permeability of shales, economically viable production requires hydraulic fracturing of the re

  12. Use of carbon monoxide and hydrogen by a bacteria-animal symbiosis from seagrass sediments.

    Science.gov (United States)

    Kleiner, Manuel; Wentrup, Cecilia; Holler, Thomas; Lavik, Gaute; Harder, Jens; Lott, Christian; Littmann, Sten; Kuypers, Marcel M M; Dubilier, Nicole

    2015-12-01

    The gutless marine worm Olavius algarvensis lives in symbiosis with chemosynthetic bacteria that provide nutrition by fixing carbon dioxide (CO2 ) into biomass using reduced sulfur compounds as energy sources. A recent metaproteomic analysis of the O. algarvensis symbiosis indicated that carbon monoxide (CO) and hydrogen (H2 ) might also be used as energy sources. We provide direct evidence that the O. algarvensis symbiosis consumes CO and H2 . Single cell imaging using nanoscale secondary ion mass spectrometry revealed that one of the symbionts, the γ3-symbiont, uses the energy from CO oxidation to fix CO2 . Pore water analysis revealed considerable in-situ concentrations of CO and H2 in the O. algarvensis environment, Mediterranean seagrass sediments. Pore water H2 concentrations (89-2147 nM) were up to two orders of magnitude higher than in seawater, and up to 36-fold higher than previously known from shallow-water marine sediments. Pore water CO concentrations (17-51 nM) were twice as high as in the overlying seawater (no literature data from other shallow-water sediments are available for comparison). Ex-situ incubation experiments showed that dead seagrass rhizomes produced large amounts of CO. CO production from decaying plant material could thus be a significant energy source for microbial primary production in seagrass sediments.

  13. [Seagrass ecosystems: contributions to and mechanisms of carbon sequestration].

    Science.gov (United States)

    Qiu, Guang-Long; Lin, Hsing-Juh; Li, Zong-Shan; Fan, Hang-Qing; Zhou, Hao-Lang; Liu, Guo-Hua

    2014-06-01

    The ocean's vegetated habitats, in particular seagrasses, mangroves and salt marshes, each capture and store a comparable amount of carbon per year, forming the Earth's blue carbon sinks, the most intense carbon sinks on the planet. Seagrass meadows, characterized by high primary productivity, efficient water column filtration and sediment stability, have a pronounced capacity for carbon sequestration. This is enhanced by low decomposition rates in anaerobic seagrass sediments. The carbon captured by seagrass meadows contributes significantly to the total blue carbon. At a global scale, seagrass ecosystems are carbon sink hot spots and have profound influences on the global carbon cycle. This importance combined with the many other functions of seagrass meadows places them among the most valuable ecosystems in the world. Unfortunately, seagrasses are declining globally at an alarming rate owing to anthropogenic disturbances and climate change, making them also among the most threatened ecosystems on the Earth. The role of coastal systems in carbon sequestration has received far too little attention and thus there are still many uncertainties in evaluating carbon sequestration of global seagrass meadows accurately. To better assess the carbon sequestration of global seagrass ecosystems, a number of scientific issues should be considered with high priorities: 1) more accurate measurements of seagrass coverage at national and global levels; 2) more comprehensive research into species- and location-specific carbon sequestration efficiencies; 3) in-depth exploration of the effects of human disturbance and global climate change on carbon capture and storage by seagrass ecosystems.

  14. A Predictive Model for Investigating Seagrass Paleoecology, Biogeography and Diversity

    Science.gov (United States)

    Sewall, J. O.; Clementz, M. T.

    2008-12-01

    Seagrasses are highly productive components of coastal ecosystems that play significant roles in the flow of nutrients and the modulation of physical conditions within the world's oceans. However, in spite of the significant role seagrasses play today, the fossil record contains little evidence of the distribution and abundance of seagrass species in the past and many questions about their biology, ecology, and evolutionary history remain. We have developed, and present here, a parameter driven numerical model of global seagrass biogeography and diversity appropriate for paleontological and paleoecological investigations. The global distribution of seagrasses in our model is dependent on four input parameters, water temperature, water salinity, water depth, and photosynthetically available radiation at depth. With these limited inputs, our model captures both the location and biodiversity of modern seagrass distributions well. The simplicity of our model and its robust representation of modern conditions give it tremendous flexibility for applications throughout the ~70 Ma long history of seagrasses. Paleo ocean temperatures, salinity, water depths, and incident radiation are available from paleoclimatic/proxy datasets and/or numerical simulations of past environmental/climatic conditions, thus permitting investigations into time specific seagrass biogeography and diversity throughout its evolutionary history. In addition, the simplicity of our model allows for theoretical investigations of seagrass paleoecology and response to environmental changes. Both applications will contribute significantly to furthering our understanding of seagrasses, seagrass dominated ecosystems, and the roles they have played in the earth system over the past 70 Ma.

  15. Sulfide intrusion and detoxification in seagrasses ecosystems

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald; Holmer, Marianne

    strategies of seagrasses to sustain sulfide intrusion. Using stable isotope tracing, scanning electron microscopy with x-ray analysis, tracing sulfur compounds combined with ecosystem parameters we found different spatial, intraspecific and interspecific strategies to cope with sulfidic sediments. 1......) Tolerance, by elimination (eg. Zostera marina); where we found precipitation of sulfide as non-toxic elemental sulfur on the inner wall of the root lacunae. 2) Utilization (eg. Z. marina), where seagrasses detoxify and incorporate sulfides by active uptake and metabolize to sulfate, representing a non...

  16. Shale gas characteristics of the Lower Toarcian Posidonia Shale in Germany: from basin to nanometre scale

    Science.gov (United States)

    Schulz, Hans-Martin; Bernard, Sylvain; Horsfield, Brian; Krüger, Martin; Littke, Ralf; di primio, Rolando

    2013-04-01

    The Early Toarcian Posidonia Shale is a proven hydrocarbon source rock which was deposited in a shallow epicontinental basin. In southern Germany, Tethyan warm-water influences from the south led to carbonate sedimentation, whereas cold-water influxes from the north controlled siliciclastic sedimentation in the northwestern parts of Germany and the Netherlands. Restricted sea-floor circulation and organic matter preservation are considered to be the consequence of an oceanic anoxic event. In contrast, non-marine conditions led to sedimentation of coarser grained sediments under progressively terrestrial conditions in northeastern Germany The present-day distribution of Posidonia Shale in northern Germany is restricted to the centres of rift basins that formed in the Late Jurassic (e.g., Lower Saxony Basin and Dogger Troughs like the West and East Holstein Troughs) as a result of erosion on the basin margins and bounding highs. The source rock characteristics are in part dependent on grain size as the Posidonia Shale in eastern Germany is referred to as a mixed to non-source rock facies. In the study area, the TOC content and the organic matter quality vary vertically and laterally, likely as a consequence of a rising sea level during the Toarcian. Here we present and compare data of whole Posidonia Shale sections, investigating these variations and highlighting the variability of Posidonia Shale depositional system. During all phases of burial, gas was generated in the Posidonia Shale. Low sedimentation rates led to diffusion of early diagenetically formed biogenic methane. Isochronously formed diagenetic carbonates tightened the matrix and increased brittleness. Thermogenic gas generation occurred in wide areas of Lower Saxony as well as in Schleswig Holstein. Biogenic methane gas can still be formed today in Posidonia Shale at shallow depth in areas which were covered by Pleistocene glaciers. Submicrometric interparticle pores predominate in immature samples. At

  17. The emergence of molecular profiling and omics techniques in seagrass biology; furthering our understanding of seagrasses.

    Science.gov (United States)

    Davey, Peter A; Pernice, Mathieu; Sablok, Gaurav; Larkum, Anthony; Lee, Huey Tyng; Golicz, Agnieszka; Edwards, David; Dolferus, Rudy; Ralph, Peter

    2016-09-01

    Seagrass meadows are disappearing at alarming rates as a result of increasing coastal development and climate change. The emergence of omics and molecular profiling techniques in seagrass research is timely, providing a new opportunity to address such global issues. Whilst these applications have transformed terrestrial plant research, they have only emerged in seagrass research within the past decade; In this time frame we have observed a significant increase in the number of publications in this nascent field, and as of this year the first genome of a seagrass species has been sequenced. In this review, we focus on the development of omics and molecular profiling and the utilization of molecular markers in the field of seagrass biology. We highlight the advances, merits and pitfalls associated with such technology, and importantly we identify and address the knowledge gaps, which to this day prevent us from understanding seagrasses in a holistic manner. By utilizing the powers of omics and molecular profiling technologies in integrated strategies, we will gain a better understanding of how these unique plants function at the molecular level and how they respond to on-going disturbance and climate change events.

  18. What lies beneath: why knowledge of belowground biomass dynamics is crucial to effective seagrass management

    NARCIS (Netherlands)

    Vonk, J.A.; Christianen, M.J.A.; Stapel, J.; O’Brien, K.R.

    2015-01-01

    Conservation of seagrasses meadows is important, because these habitats are ecologically important and under threat. Monitoring and modelling are essential tools for assessing seagrass condition and potential threats, however there are many seagrass indicators to choose from, and differentiating bet

  19. What lies beneath : Why knowledge of belowground biomass dynamics is crucial to effective seagrass management

    NARCIS (Netherlands)

    Vonk, J. Arie; Christianen, Marjolijn J. A.; Stapel, Johan; O'Brien, Katherine R.

    2015-01-01

    Conservation of seagrasses meadows is important, because these habitats are ecologically important and under threat. Monitoring and modelling are essential tools for assessing seagrass condition and potential threats, however there are many seagrass indicators to choose from, and differentiating bet

  20. What lies beneath : Why knowledge of belowground biomass dynamics is crucial to effective seagrass management

    NARCIS (Netherlands)

    Vonk, J. Arie; Christianen, Marjolijn J. A.; Stapel, Johan; O'Brien, Katherine R.

    2015-01-01

    Conservation of seagrasses meadows is important, because these habitats are ecologically important and under threat. Monitoring and modelling are essential tools for assessing seagrass condition and potential threats, however there are many seagrass indicators to choose from, and differentiating

  1. Manatees mapping seagrass (USA & Puerto Rico)

    Science.gov (United States)

    Slone, Daniel H.; Reid, James P.; Kenworthy, W. Judson; Di Carlo, Giuseppe; Butler, Susan M.

    2012-01-01

    West Indian manatees (Trichechus manatus) are secretive creatures. While some of their behaviours at winter aggregation sites in Florida are readily visible to the casual observer, many of their habits and movements are difficult to observe. They rely on submerged vegetation for nutrition, and seagrasses are one of their most important food sources.

  2. MEASURING INVERTEBRATE GRAZING ON SEAGRASSES AND EPIPHYTES

    Science.gov (United States)

    The chapter describes methods to assess grazing rates, grazer preferences, and grazer impacts, by mobile organisms living in the canopy or in the rhizome layer in any seagrass system. One set of methods quantifies grazing activity in small to medium sized, mobile organisms livin...

  3. Requiem for an eastern Pacific seagrass bed.

    Science.gov (United States)

    Cortés, J

    2001-12-01

    Few papers concerning seagrasses of the eastern Pacific have been published. This paper presents the first ecological data on the seagrass, Ruppia maritima, from a non-lagoonal setting in the eastern Pacific. A 5000 m2 patch formed by R. maritima, at Playa Iguanita, Bahía Culebra, Pacific coast of Costa Rica was studied. Plant density and leaf length of R. maritima were determined along two transects on different dates. Above and below ground biomass were calculated along one transect. Plant density ranged from 1590 to 8630 individuals m(-2) along the two transects, with means of 5990 +/- 1636 and 6100 +/- 1876 plants m(-2) for transect 1 and 2, respectively. Longest leaf length per plant varied between 0.5 and 23.0 cm. Leaf biomass (LB) ranged from 10 to 97 gm(-2), and root-rhizome biomass (RB) from 31 to 411 gm(-2), resulting in RB:LB ratios of 3.07 to 15.27. Total biomass at Bahía Culebra was lower than at tropical lagoons on the Pacific coast of Mexico, but higher than in the Gulf of Mexico. The below ground: above ground biomass ratio was much higher at Bahía Culebra than at other sites on the Pacific coast of Mexico and the Gulf of Mexico. Another seagrass present at Bahía Culebra was Halophila baillonii, with low densities on the deepest section of the patch. At least 44 invertebrate species associated with the seagrass bed have also been identified. The patch at Playa Iguanita and other sites within Bahía Culebra, as well as their associated organisms, disappeared after a severe storm in June 1996. No seagrasses have been found in the area or in any other location on the Pacific coast of Costa Rica since then.

  4. Fire-resistance, physical, and mechanical characterization of particleboard containing Oceanic Posidonia waste

    Directory of Open Access Journals (Sweden)

    Saval, J. M.

    2014-06-01

    Full Text Available In this work, particleboards manufactured with Oceanic Posidonia waste and bonded with cement are investigated. The particleboards are made with 3/1.5/0.5 parts of cement per part of Posidonia waste. The physical properties of bulk density, swelling, surface absorption, and dimensional changes due to relative humidity as well as the mechanical properties of modulus of elasticity, bending strength, surface soundness, perpendicular tensile strength and impact resistance are studied. In terms of the above properties, the best results were obtained for particleboards with high cement content and when the waste “leaves” are treated (crushed before board fabrication, due to internal changes to the board structure under these conditions. Based on the results of fire tests, the particleboard is non-flammable without any fire-resistant treatment.En esta investigación se han diseñado y fabricado tableros con residuo de Posidonia Oceánica y cemento. Los tableros se han fabricado con 3/1.5/0.5 partes de cemento por cada parte de Posidonia estudiándose sus propiedades físicas (densidad, hinchazón, absorción superficial, variaciones dimensionales por humedad y mecánicas (módulo de elasticidad, resistencia a flexión, al arranque de superficie, al arranque de tornillo, a la tracción perpendicular y al choque. Se observa una mejora de los resultados de resistencia mecánica con el incremento de la cantidad de cemento y si la hoja del residuo es previamente tratada ya que proporciona una mejor estructura interna en el tablero. Además, tras los ensayos de reacción al fuego, se observa que el material es no inflamable sin ningún tipo de tratamiento ignifugante.

  5. A framework for the resilience of seagrass ecosystems.

    Science.gov (United States)

    Unsworth, Richard K F; Collier, Catherine J; Waycott, Michelle; Mckenzie, Len J; Cullen-Unsworth, Leanne C

    2015-11-15

    Seagrass ecosystems represent a global marine resource that is declining across its range. To halt degradation and promote recovery over large scales, management requires a radical change in emphasis and application that seeks to enhance seagrass ecosystem resilience. In this review we examine how the resilience of seagrass ecosystems is becoming compromised by a range of local to global stressors, resulting in ecological regime shifts that undermine the long-term viability of these productive ecosystems. To examine regime shifts and the management actions that can influence this phenomenon we present a conceptual model of resilience in seagrass ecosystems. The model is founded on a series of features and modifiers that act as interacting influences upon seagrass ecosystem resilience. Improved understanding and appreciation of the factors and modifiers that govern resilience in seagrass ecosystems can be utilised to support much needed evidence based management of a vital natural resource. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Rapidly spreading seagrass invades the Caribbean with unknown ecological consequences

    Science.gov (United States)

    Rogers, Caroline S.; Willette, Demian A; Miller, Jeff

    2014-01-01

    The non-native seagrass Halophila stipulacea has spread rapidly throughout the Caribbean Sea (Willette et al. 2014); without additional research, the ecological ramifications of this invasion are difficult to predict. Biodiversity, connectivity of marine ecosystems, and recovery of degraded coral reefs could all be affected. The invasive seagrass, native to the Red Sea and Indian Ocean, has taken over sand bottoms and intermixed with or replaced native seagrasses, including Thalassia testudinum, Syringodium filiforme, and Halodule wrightii.

  7. Detachment and flow cytometric quantification of seagrass-associated bacteria.

    Science.gov (United States)

    Trevathan-Tackett, Stacey; Macreadie, Peter; Ralph, Peter; Seymour, Justin

    2014-07-01

    A new protocol was developed to detach bacteria from seagrass tissue and subsequently enumerate cells using flow cytometry (FCM). A method involving addition of the surfactant Tween 80 and vortexing resulted in maximum detachment efficiency of seagrass attached bacteria, providing a robust protocol for precisely enumerating seagrass-associated bacteria with FCM. Using this approach we detected cell concentrations between 2.0×10(5) and 8.0×10(6)cells mg(-1) DW tissue.

  8. Effects of common seagrass restoration methods on ecosystem structure in subtropical seagrass meadows.

    Science.gov (United States)

    Bourque, Amanda S; Fourqurean, James W

    2014-06-01

    Seagrass meadows near population centers are subject to frequent disturbance from vessel groundings. Common seagrass restoration methods include filling excavations and applying fertilizer to encourage seagrass recruitment. We sampled macrophytes, soil structure, and macroinvertebrate infauna at unrestored and recently restored vessel grounding disturbances to evaluate the effects of these restoration methods on seagrass ecosystem structure. After a year of observations comparing filled sites to both undisturbed reference and unrestored disturbed sites, filled sites had low organic matter content, nutrient pools, and primary producer abundance. Adding a nutrient source increased porewater nutrient pools at disturbed sites and in undisturbed meadows, but not at filled sites. Environmental predictors of infaunal community structure across treatments included soil texture and nutrient pools. At the one year time scale, the restoration methods studied did not result in convergence between restored and unrestored sites. Particularly in filled sites, soil conditions may combine to constrain rapid development of the seagrass community and associated infauna. Our study is important for understanding early recovery trajectories following restoration using these methods.

  9. Seagrass restoration enhances "blue carbon" sequestration in coastal waters.

    Science.gov (United States)

    Greiner, Jill T; McGlathery, Karen J; Gunnell, John; McKee, Brent A

    2013-01-01

    Seagrass meadows are highly productive habitats that provide important ecosystem services in the coastal zone, including carbon and nutrient sequestration. Organic carbon in seagrass sediment, known as "blue carbon," accumulates from both in situ production and sedimentation of particulate carbon from the water column. Using a large-scale restoration (>1700 ha) in the Virginia coastal bays as a model system, we evaluated the role of seagrass, Zosteramarina, restoration in carbon storage in sediments of shallow coastal ecosystems. Sediments of replicate seagrass meadows representing different age treatments (as time since seeding: 0, 4, and 10 years), were analyzed for % carbon, % nitrogen, bulk density, organic matter content, and ²¹⁰Pb for dating at 1-cm increments to a depth of 10 cm. Sediment nutrient and organic content, and carbon accumulation rates were higher in 10-year seagrass meadows relative to 4-year and bare sediment. These differences were consistent with higher shoot density in the older meadow. Carbon accumulation rates determined for the 10-year restored seagrass meadows were 36.68 g C m⁻² yr⁻¹. Within 12 years of seeding, the restored seagrass meadows are expected to accumulate carbon at a rate that is comparable to measured ranges in natural seagrass meadows. This the first study to provide evidence of the potential of seagrass habitat restoration to enhance carbon sequestration in the coastal zone.

  10. microbiological parameters and maturity degree during composting of Posidonia oceanica residues, mixed with vegetable wastes in semi-arid pedo-climatic condition

    Institute of Scientific and Technical Information of China (English)

    SAIDI Neyla; KOUKI Soulwene; M'HIRI Fadhel; JEDIDI Naceur; MAHROUK Meriam; HASSEN Abdennaceur; OUZARI Hadda

    2009-01-01

    The aim of this study was to characterize the biological stability and maturity degree of compost during a controlled pile-composting trial of mixed vegetable residues (VR) collected from markets of Tunis City with residues of Posidonia oceanica (PoR), collected from Tunis beaches. The accumulation in beaches (as well as their removal) constitutes a serious environmental problem in all Mediterranean countries particularly in Tunisia. Aerobic-thermophilic composting is the most reasonable way to profit highly-valuable content of organic matter in these wastes for agricultural purposes. The physical, chemical, and biological parameters were monitored during composting over 150 d. The most appropriate parameters were selected to establish the maturity degree. The main result of this research was the deduction of the following maturity criterion: (a) a C/N ratio 80%. These five parameters, considered jointly are indicative of a high maturity degree and thus of a high-quality organic amendment which employed in a rational way, may improve soil fertility and soil quality. The mature compost was relatively rich in N (13.0 g/kg), P (9.48 g/kg) and MgO (15.80 g/kg). Thus composting definitively constitutes the most optimal option to exploit these wastes.

  11. Microbiological parameters and maturity degree during composting of Posidonia oceanica residues mixed with vegetable wastes in semi-arid pedo-climatic condition.

    Science.gov (United States)

    Saidi, Neyla; Kouki, Soulwene; M'hiri, Fadhel; Jedidi, Naceur; Mahrouk, Meriam; Hassen, Abdennaceur; Ouzari, Hadda

    2009-01-01

    The aim of this study was to characterize the biological stability and maturity degree of compost during a controlled pile-composting trial of mixed vegetable residues (VR) collected from markets of Tunis City with residues of Posidonia oceanica (PoR), collected from Tunis beaches. The accumulation in beaches (as well as their removal) constitutes a serious environmental problem in all Mediterranean countries particularly in Tunisia. Aerobic-thermophilic composting is the most reasonable way to profit highly-valuable content of organic matter in these wastes for agricultural purposes. The physical, chemical, and biological parameters were monitored during composting over 150 d. The most appropriate parameters were selected to establish the maturity degree. The main result of this research was the deduction of the following maturity criterion: (a) C/N ratio 80%. These five parameters, considered jointly are indicative of a high maturity degree and thus of a high-quality organic amendment which employed in a rational way, may improve soil fertility and soil quality. The mature compost was relatively rich in N (13.0 g/kg), P (4.74 g/kg) and MgO (15.80 g/kg). Thus composting definitively constitutes the most optimal option to exploit these wastes.

  12. Gulf-Wide Information System, Environmental Sensitivity Index Seagrass, Geographic NAD83, LDWF (2001) [esi_seagrass_LDWF_2001

    Data.gov (United States)

    Louisiana Geographic Information Center — This data set contains Environmental Sensitivity Index (ESI) seagrass data of coastal Louisiana. The ESI is a classification and ranking system, which characterizes...

  13. Spatially explicit feedbacks between seagrass meadows, sediment, and light: habitat suitability for seagrass growth

    Science.gov (United States)

    Carr, J. A.; D'Odorico, P.; McGlathery, K.; Wiberg, P. L.

    2011-12-01

    In shallow costal bays in which nutrient loading and riverine inputs are low, turbidity, and the consequent light environment are controlled by resuspension of bed sediments due to wind-waves and tidal currents. When sediment resuspension is high, resultant low light environments can limit benthic primary productivity. However, both currents and waves are affected by the presence of benthic plants such as seagrass. Moreover, vegetated areas influence a larger area than they footprint, including an adjacent downstream area. This region, while barren of seagrass, exhibits reduced shear stresses until boundary layer reformation occurs. We develop a simplistic approach to explore how the patchy structure of seagrass meadows may affect sediment resuspension and the consequent light environment under tidal and wind-wave forcing due to the presence of this sheltered region. In order to investigate the effect of patch modified hydrodynamics we generated heterogeneous vegetation covers comprised of a mosaic of randomly distributed patches with exponentially distributed radii. These heterogenous landscapes were generated from two perspectives. First, circular patches were randomly placed on a bare landscape; with each circular patch assumed to be a seagrass meadow. Second, starting from a landscape assumed to be homogenous meadow with constant shoot density, circular gaps were randomly generated. Each gap was considered a disturbance that completely removed all seagrass from within the circular region. Fractional cover of vegetation on the landscape was used to facilitate comparisons across landscape realizations and perspectives. Each landscape realization was then used to partition wave and current shear stresses on the landscape. Total suspended sediment and light attenuation characteristics were then calculated and averaged over the landscape to examine how both fractional cover and mean water depth affect the bulk sediment and light environment from the meadow or gap

  14. Leaf transport in mimic mangrove forests and seagrass beds

    NARCIS (Netherlands)

    Gillis, L.G.; Bouma, T.J.; Kiswara, W.; Ziegler, A.D.; Herman, P.M.J.

    2014-01-01

    Mangrove forests and seagrass beds are thought to exchange particulate organic material, especially in the form of leaves. However, relatively little is known about the trapping capacity of mangrove above-ground roots and seagrass plants for leaf segments. We aimed to identify the major factors

  15. Consensus forecasting of intertidal seagrass habitat in the Wadden Sea

    NARCIS (Netherlands)

    Folmer, E.O.; van Beusekom, J.E.E.; Dolch, T; Gräwe, U.; van Katwijk, M.M.; Kolbe, K.; Philippart, C.J.M.

    2016-01-01

    1. After the dramatic eutrophication-induced decline of intertidal seagrasses in the 1970s, theWadden Sea has shown diverging developments. In the northern Wadden Sea, seagrass bedshave expanded and become denser, while in the southern Wadden Sea, only small beds withlow shoot densities are found. A

  16. Integrating scales of seagrass monitoring to meet conservation needs

    Science.gov (United States)

    Neckles, Hilary A.; Kopp, Blaine S.; Peterson, Bradley J.; Pooler, Penelope S.

    2012-01-01

    We evaluated a hierarchical framework for seagrass monitoring in two estuaries in the northeastern USA: Little Pleasant Bay, Massachusetts, and Great South Bay/Moriches Bay, New York. This approach includes three tiers of monitoring that are integrated across spatial scales and sampling intensities. We identified monitoring attributes for determining attainment of conservation objectives to protect seagrass ecosystems from estuarine nutrient enrichment. Existing mapping programs provided large-scale information on seagrass distribution and bed sizes (tier 1 monitoring). We supplemented this with bay-wide, quadrat-based assessments of seagrass percent cover and canopy height at permanent sampling stations following a spatially distributed random design (tier 2 monitoring). Resampling simulations showed that four observations per station were sufficient to minimize bias in estimating mean percent cover on a bay-wide scale, and sample sizes of 55 stations in a 624-ha system and 198 stations in a 9,220-ha system were sufficient to detect absolute temporal increases in seagrass abundance from 25% to 49% cover and from 4% to 12% cover, respectively. We made high-resolution measurements of seagrass condition (percent cover, canopy height, total and reproductive shoot density, biomass, and seagrass depth limit) at a representative index site in each system (tier 3 monitoring). Tier 3 data helped explain system-wide changes. Our results suggest tiered monitoring as an efficient and feasible way to detect and predict changes in seagrass systems relative to multi-scale conservation objectives.

  17. Contribution of genetics and genomics to seagrass biology and conservation

    NARCIS (Netherlands)

    Procaccini, Gabriele; Olsen, Jeanine L.; Reusch, Thorsten B. H.

    2007-01-01

    Genetic diversity is one of three forms of biodiversity recognized by the IUCN as deserving conservation along with species and ecosystems. Seagrasses provide all three levels in one. This review addresses the latest advances in our understanding of seagrass population genetics and genomics within t

  18. Seagrass epiphytes: useful indicator, potential biological criterion, or forlorn hope?

    Science.gov (United States)

    Epiphytes on seagrasses have been studied for more than 50 years, and proposed as an indicator of anthropogenic nutrient enrichment for over 30 years. Epiphytes have been correlated with seagrass declines, causally related to nutrient additions in both field and mesocosm experim...

  19. First experimental evidence of corals feeding on seagrass matter

    NARCIS (Netherlands)

    Lai, S.; Gillis, L.G.; Mueller, C.; Bouma, T.J.; Guest, J.R.; Last, K.S.; Ziegler, A.D.; Todd, P.A.

    2013-01-01

    We present the first experimental evidence of a coral (Oulastrea crispata) ingesting and assimilating seagrass material. Tropical seagrass meadows export a substantial portion of their productivity and can provide an important source of nutrients to neighbouring systems such as coral reefs; however,

  20. Consumer depletion alters seagrass resistance to an invasive macroalga.

    Science.gov (United States)

    Caronni, Sarah; Calabretti, Chiara; Delaria, Maria Anna; Bernardi, Giuseppe; Navone, Augusto; Occhipinti-Ambrogi, Anna; Panzalis, Pieraugusto; Ceccherelli, Giulia

    2015-01-01

    Few field studies have investigated how changes at one trophic level can affect the invasibility of other trophic levels. We examined the hypothesis that the spread of an introduced alga in disturbed seagrass beds with degraded canopies depends on the depletion of large consumers. We mimicked the degradation of seagrass canopies by clipping shoot density and reducing leaf length, simulating natural and anthropogenic stressors such as fish overgrazing and water quality. Caulerpa racemosa was transplanted into each plot and large consumers were excluded from half of them using cages. Potential cage artifacts were assessed by measuring irradiance, scouring by leaf movement, water flow, and sedimentation. Algal invasion of the seagrass bed differed based on the size of consumers. The alga had higher cover and size under the cages, where the seagrass was characterized by reduced shoot density and canopy height. Furthermore, canopy height had a significant effect depending on canopy density. The alteration of seagrass canopies increased the spread of C. racemosa only when large consumers were absent. Our results suggest that protecting declining habitats and/or restoring fish populations will limit the expansion of C. racemosa. Because MPAs also enhance the abundance and size of fish consuming seagrass they can indirectly promote algal invasion. The effects of MPAs on invasive species are context dependent and require balancing opposing forces, such as the conservation of seagrass canopy structure and the protection of fish grazing the seagrass.

  1. The mapping of the Posidonia oceanica (L.) Delile barrier reef meadow in the southeastern Gulf of Tunis (Tunisia)

    Science.gov (United States)

    Hachani, Mohamed Amine; Ziadi, Boutheina; Langar, Habib; Sami, Djallouli Aslem; Turki, Souad; Aleya, Lotfi

    2016-09-01

    Barrier reefs are among the most important ecomorphosis for Posidonia oceanica meadows and have long been subjected to anthropic pressures. The authors mapped the entire Sidi Rais (northeastern Tunisia) Posidonia oceanica barrier reef by means of remote sensing based on processing a satellite image acquired via Google Earth © software, coupled with field observations obtained by snorkeling. The map thus produced represents the P. oceanica barrier reef in its current state, covering a total area of 156.77 ha, the reef being divided into three distinct sections separated by reverse flows with each section subject to varied anthropic factors and disturbances.

  2. Preparation and characterization of new succinic anhydride grafted Posidonia for the removal of organic and inorganic pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Chadlia, Aguir, E-mail: aguirc@yahoo.ca [Unite de Recherche de Chimie Appliquee et Environnement, Faculte des Sciences de Monastir, 5000 (Tunisia); Mohamed, Khalfaoui [Unite de Recherche de Physique Quantique, Faculte des Sciences de Monastir, 5000 (Tunisia); Najah, Laribi; Farouk, M' henni Mohamed [Unite de Recherche de Chimie Appliquee et Environnement, Faculte des Sciences de Monastir, 5000 (Tunisia)

    2009-12-30

    The present work describes the preparation of new chelating materials derived from Posidonia for adsorption of heavy metal ions and dye in aqueous solution. The first part of this report deals with the chemical modification of Posidonia with succinic anhydride. Thus, we have obtained materials with various succinyl groups contents (from 29.8 to 39.2%). The obtained materials were characterized by infrared and CP/MAS {sup 13}C-RMN spectroscopy. The rate of succinyl content of the modified Posidonia was determined by saponification. The second part is devoted to the evaluation of the adsorption capacity of metal ions such as Pb{sup 2+} and dye such as direct red 75 (DR75) for raw and modified Posidonia materials. Two possible ways for the adsorption of these pollutants are studied: adsorption of each pollutant alone onto these supports, and cumulative adsorption of both metal ions and dye on the same supports. In the last case, the pollutant is adsorbed successively from two different solutions. The effects of pollutants concentration, support dose, pH, contact time and temperature on adsorption of each pollutant were evaluated. The results showed that the raw and modified Posidonia show a high capacity for Pb{sup 2+} adsorption. The capacity of modified Posidonia saturated with Pb{sup 2+} to adsorb DR75 was found 147.12 mg g{sup -1}. While the adsorption capacity of the nonsaturated modified Posidonia was equal to 81.63 mg g{sup -1}. The pseudo-second-order model was the best to represent adsorption kinetics of DR75. The pseudo-first-order model would be better for fitting the adsorption kinetic process of Pb{sup 2+} onto raw and modified Posidonia. The adsorption isotherms of Pb{sup 2+} could be described by the Jossens equation model. Any of the tested models can describe the adsorption of DR75 onto the studied materials. These results confirm that the adsorption of DR75 from aqueous solution was multilayer.

  3. Photosynthethic carbon reduction by seagrasses exposed to ultraviolet B radiation

    Science.gov (United States)

    1979-01-01

    The species of seagrasses were selected on the basis of their dominance in the marine system, contribution to total productivity, and importance to the life histories of organisms in the Indian River lagoon system along the central Florida east coast. The three seagrasses were Halophilia engelmannii, Halodule wrightii, and Syringodium filiforme. These seagrasses form an excellent experimental system as their areas of dominance fall more or less along a natural gradient of UV-B and photosynthetically active radiation (PAR) penetration. The sensitivity of photosynthesis in the seagrasses was determined and their photosynthetic response to levels of UV-B simulating atmospheric ozone depletion was monitored. Further experiments explore the possible attenuation or repair of UV-B induced photosynthetic inhibition by PAR, the role of epiphytic growth upon seagrasses as a protective UV-B shield, and the inhibition of photosynthesis in response to UV-A is studied.

  4. Relative foraminiferan abundance as an indicator of seagrass sediment health:

    Science.gov (United States)

    Cajandig, P.; Quiros, A.; Nolan, H.; Tallman, R.; Cooper, N.; Ayala, J.; Courtier, C.

    2013-12-01

    Authors: Patrick Cajandig*, Jose Ayala**, Nathaniel Cooper**, Catherine Courtier**, Hannah Nolan**, Rachelle Tallman**, T.E. Angela L. Quiros** * Davis High-School CA, **University of California Santa Cruz, Ecology and Evolutionary Biology Department Seagrasses are a key component in coastal ecosystems. Found in shallow marine environments, they make a large contribution to coastal ecosystem health by sustaining water quality, stabilizing the sea bottom, and providing habitat as well as food for other organisms. Seagrasses accumulate tiny grains of sediment, increasing water clarity. Just like barren hills are prone to erosion compared to vegetated, rooted down hills, we find a similar situation in the ocean. Seagrasses have broad roots that extend vertically and horizontally to help stabilize the seabed. Seagrasses support a whole ecosystem, because some organisms feed off of the seagrass alone, while others feed off the inhabitants of the seagrass. The quality of sediment is a vital part of seagrass health, just like nutrient rich soils are important to land plants. But what in seagrass sediment is a good indication of health? We hypothesize that seagrass health measures such as percent cover and seagrass species diversity are related to the abundance of foraminiferans relative to other seagrass sediment components. My mentor, T. E. Angela L. Quiros, from the University of California, Santa Cruz (UCSC), collected the sediment samples from seagrass beds in the Philippines. Samples were dried and brought to UCSC for sediment sieving. We used different sized sieves to sort the sediment. These sieves ranged from coarse to very fine sieves (Phi -2.0 (coarse) through +3.0 (fine) going in 0.5 intervals on a log scale). We weighed the sediment that was caught in each tray and separated them into bags of different size classes. To analyze each sample, we subsampled four size classes (Phi's -2.0, -1.5,-1.0, 0.0), and used a dissecting scope to identify and then weigh the

  5. Spatially explicit feedbacks between seagrass meadow structure, sediment and light: Habitat suitability for seagrass growth

    Science.gov (United States)

    Carr, Joel; D'Odorico, Paul; McGlathery, Karen; Wiberg, Patricia L.

    2016-01-01

    In shallow coastal bays where nutrient loading and riverine inputs are low, turbidity, and the consequent light environment are controlled by resuspension of bed sediments due to wind-waves and tidal currents. High sediment resuspension and low light environments can limit benthic primary productivity; however, both currents and waves are affected by the presence of benthic plants such as seagrass. This feedback between the presence of benthic primary producers such as seagrass and the consequent light environment has been predicted to induce bistable dynamics locally. However, these vegetated areas influence a larger area than they footprint, including a barren adjacent downstream area which exhibits reduced shear stresses. Here we explore through modeling how the patchy structure of seagrass meadows on a landscape may affect sediment resuspension and the consequent light environment due to the presence of this sheltered region. Heterogeneous vegetation covers comprising a mosaic of randomly distributed patches were generated to investigate the effect of patch modified hydrodynamics. Actual cover of vegetation on the landscape was used to facilitate comparisons across landscape realizations. Hourly wave and current shear stresses on the landscape along with suspended sediment concentration and light attenuation characteristics were then calculated and spatially averaged to examine how actual cover and mean water depth affect the bulk sediment and light environment. The results indicate that an effective cover, which incorporates the sheltering area, has important controls on the distributions of shear stress, suspended sediment, light environment, and consequent seagrass habitat suitability. Interestingly, an optimal habitat occurs within a depth range where, if actual cover is reduced past some threshold, the bulk light environment would no longer favor seagrass growth.

  6. Accelerating loss of seagrasses across the globe threatens coastal ecosystems

    Science.gov (United States)

    Waycott, Michelle; Duarte, Carlos M.; Carruthers, Tim J. B.; Orth, Robert J.; Dennison, William C.; Olyarnik, Suzanne; Calladine, Ainsley; Fourqurean, James W.; Heck, Kenneth L.; Hughes, A. Randall; Kendrick, Gary A.; Kenworthy, W. Judson; Short, Frederick T.; Williams, Susan L.

    2009-01-01

    Coastal ecosystems and the services they provide are adversely affected by a wide variety of human activities. In particular, seagrass meadows are negatively affected by impacts accruing from the billion or more people who live within 50 km of them. Seagrass meadows provide important ecosystem services, including an estimated $1.9 trillion per year in the form of nutrient cycling; an order of magnitude enhancement of coral reef fish productivity; a habitat for thousands of fish, bird, and invertebrate species; and a major food source for endangered dugong, manatee, and green turtle. Although individual impacts from coastal development, degraded water quality, and climate change have been documented, there has been no quantitative global assessment of seagrass loss until now. Our comprehensive global assessment of 215 studies found that seagrasses have been disappearing at a rate of 110 km2 yr−1 since 1980 and that 29% of the known areal extent has disappeared since seagrass areas were initially recorded in 1879. Furthermore, rates of decline have accelerated from a median of 0.9% yr−1 before 1940 to 7% yr−1 since 1990. Seagrass loss rates are comparable to those reported for mangroves, coral reefs, and tropical rainforests and place seagrass meadows among the most threatened ecosystems on earth. PMID:19587236

  7. Measuring the role of seagrasses in regulating sediment surface elevation

    KAUST Repository

    Potouroglou, Maria

    2017-09-13

    Seagrass meadows provide numerous ecosystem services and their rapid global loss may reduce human welfare as well as ecological integrity. In common with the other \\'blue carbon\\' habitats (mangroves and tidal marshes) seagrasses are thought to provide coastal defence and encourage sediment stabilisation and surface elevation. A sophisticated understanding of sediment elevation dynamics in mangroves and tidal marshes has been gained by monitoring a wide range of different sites, located in varying hydrogeomorphological conditions over long periods. In contrast, similar evidence for seagrasses is sparse; the present study is a contribution towards filling this gap. Surface elevation change pins were deployed in four locations, Scotland, Kenya, Tanzania and Saudi Arabia, in both seagrass and unvegetated control plots in the low intertidal and shallow subtidal zone. The presence of seagrass had a highly significant, positive impact on surface elevation at all sites. Combined data from the current work and the literature show an average difference of 31 mm per year in elevation rates between vegetated and unvegetated areas, which emphasizes the important contribution of seagrass in facilitating sediment surface elevation and reducing erosion. This paper presents the first multi-site study for sediment surface elevation in seagrasses in different settings and species.

  8. Measuring the role of seagrasses in regulating sediment surface elevation

    Science.gov (United States)

    Potouroglou, Maria; Bull, James C.; Krauss, Ken W.; Kennedy, Hilary A.; Fusi, Marco; Daffonchio, Daniele; Mangora, Mwita M.; Githaiga, Michael N.; Diele, Karen; Huxham, Mark

    2017-01-01

    Seagrass meadows provide numerous ecosystem services and their rapid global loss may reduce human welfare as well as ecological integrity. In common with the other ‘blue carbon’ habitats (mangroves and tidal marshes) seagrasses are thought to provide coastal defence and encourage sediment stabilisation and surface elevation. A sophisticated understanding of sediment elevation dynamics in mangroves and tidal marshes has been gained by monitoring a wide range of different sites, located in varying hydrogeomorphological conditions over long periods. In contrast, similar evidence for seagrasses is sparse; the present study is a contribution towards filling this gap. Surface elevation change pins were deployed in four locations, Scotland, Kenya, Tanzania and Saudi Arabia, in both seagrass and unvegetated control plots in the low intertidal and shallow subtidal zone. The presence of seagrass had a highly significant, positive impact on surface elevation at all sites. Combined data from the current work and the literature show an average difference of 31 mm per year in elevation rates between vegetated and unvegetated areas, which emphasizes the important contribution of seagrass in facilitating sediment surface elevation and reducing erosion. This paper presents the first multi-site study for sediment surface elevation in seagrasses in different settings and species.

  9. First experimental evidence of corals feeding on seagrass matter

    Science.gov (United States)

    Lai, S.; Gillis, L. G.; Mueller, C.; Bouma, T. J.; Guest, J. R.; Last, K. S.; Ziegler, A. D.; Todd, P. A.

    2013-12-01

    We present the first experimental evidence of a coral ( Oulastrea crispata) ingesting and assimilating seagrass material. Tropical seagrass meadows export a substantial portion of their productivity and can provide an important source of nutrients to neighbouring systems such as coral reefs; however, little is known about the mechanisms of this link. To investigate whether seagrass nutrient uptake via coral heterotrophy is possible, we conducted a feeding experiment with seagrass particulate and dissolved organic matter. Using gut extractions and stable isotope analyses, we determined that O. crispata ingested 15N-enriched seagrass particles and assimilated the nitrogen into its tissue at a rate of 0.75 μg N cm-2 h-1. Corals took up nitrogen from dissolved matter at a comparable rate of 0.98 μg N cm-2 h-1. While other ecological connections between seagrass meadows and reef ecosystems are well known, our results suggest a previously unstudied direct nutritional link between seagrasses and corals.

  10. Phytotoxicity of four photosystem II herbicides to tropical seagrasses.

    Directory of Open Access Journals (Sweden)

    Florita Flores

    Full Text Available Coastal waters of the Great Barrier Reef (GBR are contaminated with agricultural pesticides, including the photosystem II (PSII herbicides which are the most frequently detected at the highest concentrations. Designed to control weeds, these herbicides are equally potent towards non-target marine species, and the close proximity of seagrass meadows to flood plumes has raised concerns that seagrasses may be the species most threatened by herbicides from runoff. While previous work has identified effects of PSII herbicides on the photophysiology, growth and mortality in seagrass, there is little comparative quantitative toxicity data for seagrass. Here we applied standard ecotoxicology protocols to quantify the concentrations of four priority PSII herbicides that inhibit photochemistry by 10, 20 and 50% (IC10, IC20 and IC50 over 72 h in two common seagrass species from the GBR lagoon. The photosystems of seagrasses Zosteramuelleri and Haloduleuninervis were shown to be generally more sensitive to the PSII herbicides Diuron, Atrazine, Hexazinone and Tebuthiuron than corals and tropical microalgae. The herbicides caused rapid inhibition of effective quantum yield (∆F/F m ', indicating reduced photosynthesis and maximum effective yields (Fv/Fm corresponding to chronic damage to PSII. The PSII herbicide concentrations which affected photosynthesis have been exceeded in the GBR lagoon and all of the herbicides inhibited photosynthesis at concentrations lower than current marine park guidelines. There is a strong likelihood that the impacts of light limitation from flood plumes and reduced photosynthesis from PSII herbicides exported in the same waters would combine to affect seagrass productivity. Given that PSII herbicides have been demonstrated to affect seagrass at environmental concentrations, we suggest that revision of environmental guidelines and further efforts to reduce PSII herbicide concentrations in floodwaters may both help protect

  11. Fish responses to experimental fragmentation of seagrass habitat.

    Science.gov (United States)

    Macreadie, Peter I; Hindell, Jeremy S; Jenkins, Gregory P; Connolly, Rod M; Keough, Michael J

    2009-06-01

    Understanding the consequences of habitat fragmentation has come mostly from comparisons of patchy and continuous habitats. Because fragmentation is a process, it is most accurately studied by actively fragmenting large patches into multiple smaller patches. We fragmented artificial seagrass habitats and evaluated the impacts of fragmentation on fish abundance and species richness over time (1 day, 1 week, 1 month). Fish assemblages were compared among 4 treatments: control (single, continuous 9-m(2) patches); fragmented (single, continuous 9-m(2) patches fragmented to 4 discrete 1-m(2) patches); prefragmented/patchy (4 discrete 1-m(2) patches with the same arrangement as fragmented); and disturbance control (fragmented then immediately restored to continuous 9-m(2) patches). Patchy seagrass had lower species richness than actively fragmented seagrass (up to 39% fewer species after 1 week), but species richness in fragmented treatments was similar to controls. Total fish abundance did not vary among treatments and therefore was unaffected by fragmentation, patchiness, or disturbance caused during fragmentation. Patterns in species richness and abundance were consistent 1 day, 1 week, and 1 month after fragmentation. The expected decrease in fish abundance from reduced total seagrass area in fragmented and patchy seagrass appeared to be offset by greater fish density per unit area of seagrass. If fish prefer to live at edges, then the effects of seagrass habitat loss on fish abundance may have been offset by the increase (25%) in seagrass perimeter in fragmented and patchy treatments. Possibly there is some threshold of seagrass patch connectivity below which fish abundances cannot be maintained. The immediate responses of fish to experimental habitat fragmentation provided insights beyond those possible from comparisons of continuous and historically patchy habitat. ©2009 Society for Conservation Biology.

  12. Differences in nutrient concentrations and resources between seagrass communities on carbonate and terrigenous sediments in South Sulawesi, Indonesia

    NARCIS (Netherlands)

    Erftemeijer, P.L.A.

    1994-01-01

    Water column, sediment and plant parameters were studied in six tropical seagrass beds in South Sulawesi, Indonesia, to evaluate the relation between seagrass bed nutrient concentrations and sediment type. Coastal seagrass beds on terrigenous sediments had considerably higher biomass of

  13. Temporal variation of intertidal seagrass in Southern China (2008-2014)

    Science.gov (United States)

    Qiu, Guanglong; Short, Frederick T.; Fan, Hangqing; Liu, Guohua

    2017-07-01

    Understanding the temporal dynamics of seagrasses and the major influences on seagrass growth is critical for seagrass habitat conservation and administration. However, little work has been done regarding these issues in southern China. To examine inter-annual and seasonal variations of the intertidal Halophila ovalis community in southern China, we conducted quarterly sampling using the SeagrassNet methodology and assessed environmental conditions as well as direct anthropogenic impacts on the seagrass meadow from July 2008 to October 2014. Our study demonstrated strong inter-annual and seasonal dynamics of the intertidal seagrass meadow in the study area. Generally, the community performed best (highest seagrass cover, leaf area, shoot density, total biomass) in summer and worst in spring among the 4 seasons. The temporal variations in the seagrass community attributes (e.g. above-ground biomass) were significantly affected by precipitation, atmospheric visibility, and salinity, while leaf width was significantly negatively correlated with temperature, atmospheric visibility and salinity. Temperature was a major factor influencing the seagrass community (both macroalgae and seagrass), with temperature data showing an inverse relationship between seagrass and macroalgae. The above-ground: below-ground biomass ratio and leaf width of H. ovalis were the most sensitive plant parameters monitored when assessing environmental interactions. Human physical disturbances did not have a significant effect on seagrass dynamics in the study area. We concluded that long-term monitoring (like SeagrassNet) is valuable in understanding the relationship between environmental variables and seagrasses.

  14. Diurnal changes in pore water sulfide concentrations in the seagrass Thalassia testudinum beds: the effects of seagrasses on sulfide dynamics.

    Science.gov (United States)

    Lee; Dunton

    2000-12-20

    The dynamics of the seagrass-sulfide interaction were examined in relation to diel changes in sediment pore water sulfide concentrations in Thalassia testudinum beds and adjacent bare areas in Corpus Christi Bay and lower Laguna Madre, Texas, USA, during July 1996. Pore water sulfide concentrations in seagrass beds were significantly higher than in adjacent bare areas and showed strong diurnal variations; levels significantly decreased during mid-day at shallow sediment depths (0-10 cm) containing high below-ground tissue biomass and surface area. In contrast, diurnal variations in sediment sulfide concentrations were absent in adjacent bare patches, and at deeper (>10 cm) sediment depths characterized by low below-ground plant biomass or when the grasses were experimentally shaded. These observations suggest that the mid-day depressions in sulfide levels are linked to the transport of photosynthetically produced oxygen to seagrass below-ground tissues that fuels sediment sulfide oxidation. Lower sulfide concentrations in bare areas are likely a result of low sulfate reduction rates due to low organic matter available for remineralization. Further, high reoxidation rates due to rapid exchange between anoxic pore water and oxic overlying water are probably stimulated in bare areas by higher current velocity on the sediment surface than in seagrass beds. The dynamics of pore water sulfides in seagrass beds suggest no toxic sulfide intrusion into below-ground tissues during photosynthetic periods and demonstrate that the sediment chemical environment is considerably modified by seagrasses. The reduced sediment sulfide levels in seagrass beds during photosynthetic periods will enhance seagrass production through reduced sulfide toxicity to seagrasses and sediment microorganisms related to the nutrient cycling.

  15. Seagrass from Unified Florida Reef Tract Map (NODC Accession 0123059)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is a subset of the Unified Map representing Seagrass areas. Version 1.1 - December 2013. The Unified Florida Reef Tract Map (Unified Reef Map) provides...

  16. Antibacterial potential of three seagrasses against human pathogens

    Institute of Scientific and Technical Information of China (English)

    Rajasekaran Arumugam; Perumal Anantharaman

    2010-01-01

    Objective:To evaluate the antibacterial activity ofHalophila stipulacea (H. stipulacea), Cymodocea serrulata (C. serrulata) andHalodule pinifolia (H. pinifolia) against seven human bacterial pathogens.Methods:The antibacterial activities of the extracts on the various test organisms using disc diffusion method and Minimum Inhibitory Concentraction(MIC).Results:Methanol and chloroform extracts of all the three seagrasses were active against all the tested pathogens, whereas the hexane extract of seagrasses was not active againstStaphylococcus aureus (S. aureus). Antibacterial activity of three seagrass screened, was in the order ofH. pinifolia >H. stipulacea>C. serrulata.Conclusions: This antibacterial studies can further investigated on seagrasses for purification of bioactive substance and its possible utility in disease control.

  17. abundance and diversity of seagrass and macrofauna in the ...

    African Journals Online (AJOL)

    Mgina

    to activities associated with seaweed farming which contributed to the loss of diversity and biomass of flora ... coral reefs from turbid waters and beaches ... and some heavy metals which may damage ..... Links between humans and seagrass – ...

  18. Geospatial interface and model for predicting potential seagrass habitat

    Science.gov (United States)

    Restoration of ecosystem services provided by seagrass habitats in estuaries requires a clear understanding of the modes of action of multiple interacting stressors including nutrients, climate change, coastal land-use change, and habitat modification. We have developed a geos...

  19. Dynamics of seagrasses in a heterogeneous tropical reef ecosystem

    OpenAIRE

    Kneer, Dominik

    2014-01-01

    In tropical Southeast Asia seagrasses can be found in three types of habitats: "River estuaries" (including mud flats), "Shallow Coastal / Back Reef" (including reef flats and lagoons) and "Deep Water / Deep Coastal / Fore Reef". Especially those seagrass meadows growing on reef flats are characterized by high temporal and spatial dynamics. Research conducted in the Spermonde Archipelago, Southwest Sulawesi, Indonesia, revealed that water motion and water depth are important structuring agent...

  20. Geoengineering with seagrasses: is credit due where credit is given?

    Science.gov (United States)

    Johannessen, Sophia C.; Macdonald, Robie W.

    2016-11-01

    Blue carbon, the carbon fixed by vegetated coastal ecosystems including seagrasses, is reported to have a large potential to sequester atmospheric carbon dioxide. Planting, expanding or protecting seagrass meadows has, accordingly, been proposed as a form of geoengineering. Seagrasses are reported to account for up to 18% of the carbon burial in the world’s oceans, which is on the same order of magnitude as other proposed geoengineering techniques, including iron fertilization. International protocols have been developed to quantify carbon sequestration in seagrass meadows, with a view to awarding carbon credits under the Verified Carbon Standard. Unfortunately, because these protocols do not adequately account for post-depositional processes in marine sediment, they significantly overestimate carbon capture by seagrass beds and give an incorrect view of its distribution. Specifically, neglecting biomixing and remineralization of carbon in surface sediments biases burial rates high, while using sediment carbon inventory (soil carbon stock) over the top 1 m as a proxy for burial rate incorrectly identifies areas of high carbon burial. Seagrass beds likely provide a limited setting for geoengineering, because they generally comprise slowly-accumulating, fine to medium sand, which captures organic carbon less efficiently than fine-grained sediments or rapidly-accumulating delta deposits. While there is no question that seagrass meadows provide valuable habitat, nor that they are disappearing rapidly, their contribution to the global burial of carbon has not yet been established. The danger of geoengineering with seagrasses before reliable assessment methods have been established is that overestimated carbon offsets could lead to a net increase in emissions of carbon dioxide to the atmosphere.

  1. Accelerating loss of seagrasses across the globe threatens coastal ecosystems

    OpenAIRE

    Waycott, Michelle; Duarte, Carlos M.; Carruthers, Tim J.B.; Orth, Robert J.; Dennison, William C.; Olyarnik, Suzanne; Calladine, Ainsley; Fourgqurean, James W.; Heck, Jr., Kenneth L.; Hughes, A. Randall; Kendrick, Gary A.; Kenworthy, W. Judson; Short, Frederick T.; Williams, Susan L.

    2009-01-01

    Coastal ecosystems and the services they provide are adversely affected by a wide variety of human activities. In particular, seagrass meadows are negatively affected by impacts accruing from the billion or more people who live within 50 km of them. Seagrass meadows provide important ecosystem services, including an estimated $1.9 trillion per year in the form of nutrient cycling; an order of magnitude enhancement of coral reef fish productivity; a habitat for thousands of fish, bird, and inv...

  2. Marine algae and seagrasses of Tekirdag (Black Sea,Turkey)*

    OpenAIRE

    AYSEL, Veysel; Erdugan, Hüseyin; Dural, Berrin; SükranOkudan, E.

    2015-01-01

    Abstract In this study, marine algae and seagrasses in the upper infralittoral zone of the Black Sea coast of Tekirdag (Turkey) were investigated. A total 156 taxon (153 algae and 3 seagrasses) in species or inferior to the species category were determined. 15 of them belong to blue-green bacteria (Cyanophyta), 84 to red algae (Rhodophyta), 26 to brown algae (Heterokontophyta), 28 to green algae (Chlorophyta) and 3 to marineflowering plants (Magnoliophyta).

  3. Marine algae and seagrasses of Tekirdag (Black Sea,Turkey)*

    OpenAIRE

    AYSEL, Veysel; Erdugan, Hüseyin; Dural, Berrin; SükranOkudan, E.

    2006-01-01

    Abstract In this study, marine algae and seagrasses in the upper infralittoral zone of the Black Sea coast of Tekirdag (Turkey) were investigated. A total 156 taxon (153 algae and 3 seagrasses) in species or inferior to the species category were determined. 15 of them belong to blue-green bacteria (Cyanophyta), 84 to red algae (Rhodophyta), 26 to brown algae (Heterokontophyta), 28 to green algae (Chlorophyta) and 3 to marineflowering plants (Magnoliophyta).

  4. Biodiversity of seagrass bed in Balanan Resort - Baluran National Park

    Science.gov (United States)

    Soedarti, T.; Hariyanto, S.; Wedayanti, A.; Rahmawati, A. D.; Safitri, D. P.; Alificia, R. I.; Suwono

    2017-09-01

    Seagrass beds are flowering plants that live on the seabed. Seagrass provides a habitat for diverse flora and fauna, spawning ground, nursery ground, raising ground, and feeding ground. Balanan Resort - Baluran National Park has many beaches, such as Kajang Beach, Si Banjir Beach, Kakapa Beach, and Serondo Beach. This study was aimed to determine species composition, seagrass dominated, and the diversity index of seagrass and substrate in Resort Balanan - Baluran National Park. This research was carried out in Kajang Beach, Sibanjir Beach, Kakapa Beach, and Sirondo Beach from August to September 2015 using belt transect method, each transect consists of 15 plots (19 transects = 285 plots) and using the frame of 1x1 m. This research found seven genera and ten species : Cymodoce (C rotundata and C. serrulata), Syringodium (S. isoelifolium), Thallassodendron (T. ciliatum), Enhalus (E. acoroides) , Halodule (H. univernis and H. pinifolia), Halophila (H. ovalis and H. decipiens), and Thalassia (T. hemprichii). The diversity index of seagrass bed was moderate [H'=1.90] in Balanan Resort. The substrate of seagrass bed was mud, gravel, sand, clay sand and rubble in Balanan Resort. The dominance index was near zero [C = 0.194], that means no dominant species.

  5. Manatee grazing impacts on a mixed species seagrass bed

    Science.gov (United States)

    Lefebvre, Lynn W.; Provancha, Jane A.; Slone, Daniel H.; Kenworthy, W. Judson

    2017-01-01

    The endangered manatee Trichechus manatus is one of few large grazers in seagrass systems. To assess the long-term impacts of repeated grazing on seagrasses, we selected a study site within Kennedy Space Center in the northern Banana River, Brevard County, Florida, that was typically grazed by large numbers of manatees in spring. Two 13x13 m manatee exclosures and 2 paired open plots of equal size were established at the study site in October 1990. Shoot counts, biomass, and species composition of the co-dominant seagrass species, Syringodium filiforme and Halodule wrightii, were sampled 3 times per year in all 4 plots between October 1990 and October 1994. We used a Bayesian modelling approach, accounting for the influence of depth, to detect treatment (exclosed vs. open) effects. S. filiforme shoot counts, total biomass, and frequency of occurrence significantly increased in the exclosures. By July 1993, mean biomass values in the exclosures (167 g dry wt m-2) greatly exceeded those in the open plots (28 g dry wt m-2). H. wrightii decreased in the exclosures by 1994. Initially, both S. filiforme and H. wrightii responded positively to release from manatee grazing pressure. As S. filiforme continued to become denser in the exclosures, it gradually replaced H. wrightii. Our findings may be helpful to biologists and managers interested in predicting seagrass recovery and manatee carrying capacity of repeatedly grazed seagrass beds in areas of special significance to manatees and seagrass conservation.

  6. Rapid discrimination between four seagrass species using hybrid analysis.

    Science.gov (United States)

    Osathanunkul, M; Madesis, P; Ounjai, S; Suwannapoom, C; Jampeetong, A

    2015-04-27

    Biological species are traditionally identified based on their morphological features and the correct identification of species is critical in biological studies. However, some plant types, such as seagrass, are taxonomically problematic and difficult to identify. Furthermore, closely related seagrass species, such as Halophila spp, form a taxonomically unresolved complex. Although some seagrass taxa are easy to recognize, most species are difficult to identify without skilled taxonomic or molecular techniques. Barcoding coupled with High Resolution Melting analysis (BAR-HRM) offers a potentially reliable, rapid, and cost-effective method to confirm species. Here, DNA information of two chloroplast loci was used in combination with HRM analysis to discriminate four species of seagrass collected off the southern coast of Thailand. A distinct melting curve presenting one inflection point was generated for each species using rbcL primers. While the melting profiles of Cymodocea rotundata and Cymodocea serrulata were not statistically different, analysis of the normalized HRM curves produced with the rpoC primers allowed for their discrimination. The Bar-HRM technique showed promise in discriminating seagrass species and with further adaptations and improvements, could make for an effective and power tool for confirming seagrass species.

  7. Seagrasses in tropical Australia, productive and abundant for decades decimated overnight

    Indian Academy of Sciences (India)

    Peter C Pollard; Margaret Greenway

    2013-03-01

    Seagrass ecosystems provide unique coastal habitats critical to the life cycle of many species. Seagrasses are a major store of organic carbon. While seagrasses are globally threatened and in decline, in Cairns Harbour, Queensland, on the tropical east coast of Australia, they have flourished. We assessed seagrass distribution in Cairns Harbour between 1953 and 2012 from historical aerial photographs, Google map satellite images, existing reports and our own surveys of their distribution. Seasonal seagrass physiology was assessed through gross primary production, respiration and photosynthetic characteristics of three seagrass species, Cymodocea serrulata, Thalassia hemprichii and Zostera muelleri. At the higher water temperatures of summer, respiration rates increased in all three species, as did their maximum rates of photosynthesis. All three seagrasses achieved maximum rates of photosynthesis at low tide and when they were exposed. For nearly six decades there was little change in seagrass distribution in Cairns Harbour. This was most likely because the seagrasses were able to achieve sufficient light for growth during intertidal and low tide periods. With historical data of seagrass distribution and measures of species production and respiration, could seagrass survival in a changing climate be predicted? Based on physiology, our results predicted the continued maintenance of the Cairns Harbour seagrasses, although one species was more susceptible to thermal disturbance. However, in 2011 an unforeseen episodic disturbance – Tropical Cyclone Yasi – and associated floods lead to the complete and catastrophic loss of all the seagrasses in Cairns Harbour.

  8. The effects of water parameters on monthly seagrass percentage cover in Lawas, East Malaysia.

    Science.gov (United States)

    Ahmad-Kamil, E I; Ramli, R; Jaaman, S A; Bali, J; Al-Obaidi, J R

    2013-01-01

    Seagrass is a valuable marine ecosystem engineer. However, seagrass population is declining worldwide. The lack of seagrass research in Malaysia raises questions about the status of seagrasses in the country. The seagrasses in Lawas, which is part of the coral-mangrove-seagrass complex, have never been studied in detail. In this study, we examine whether monthly changes of seagrass population in Lawas occurred. Data on estimates of seagrass percentage cover and water physicochemical parameters (pH, turbidity, salinity, temperature, and dissolved oxygen) were measured at 84 sampling stations established within the study area from June 2009 to May 2010. Meteorological data such as total rainfall, air temperature, and Southern Oscillation Index were also investigated. Our results showed that (i) the monthly changes of seagrass percentage cover are significant, (ii) the changes correlated significantly with turbidity measurements, and (iii) weather changes affected the seagrass populations. Our study indicates seagrass percentage increased during the El-Nino period. These results suggest that natural disturbances such as weather changes affect seagrass populations. Evaluation of land usage and measurements of other water physicochemical parameters (such as heavy metal, pesticides, and nutrients) should be considered to assess the health of seagrass ecosystem at the study area.

  9. The Mediterranean

    Science.gov (United States)

    Suryawanshi, Vandana

    2017-04-01

    Learning is always a joyful experience for any human being and must always remain so. Children are happiest when they learn through play. The philosophy of my life is to keep encouraging children to think beyond they could achieve easily. I understand children are adaptive to change and take things with an open mind. They are ready to experiment new things and dare to dream big. I am fortunate to be a teacher by profession and thus I always attempt experimenting, observing and participating with other children and adults. Education is not about moulding children the way you think they should be. It is about organizing the natural longing in a human being to know. From birth children are active participants in building their own understanding. I always prepare the environment to help each child build on what they already know. It is such a great pleasure to observe every young kid become excited and curious to know when we teach them. Std 8 Geography the students are very excited to learn about this continent, with the help of Videos and a wall map the Political map of Europe with its countries shown I introduced the topic by asking 'If given a chance which place they would like to visit in Europe' , students are familiar with the countries of their favourite football players and happily pointed out their destination. The Mediterranean Region is a paradise the scenic beauty, the climate, the food along with a variety of fruits which are totally different from Asia increased the curiosity among the students. With the help of case study of the Mediterranean Sea the students were able to research and present the history, the adventure sports the aquatic life and the twenty three beautiful islands located in the Mediterranean Sea. Photos and videos helped me to explain the Mediterranean Sea The Formation of the Mediterranean Sea ( Youtube Video) which is otherwise completely enclosed by land. (The evaporating Mediterranean Sea - BBC (Video) Gibraltar Breach.mov . The

  10. AUTOMATED PRODUCTION OF SEAGRASS MAPS FROM SIDESCAN SONAR IMAGERY: ACCURACY, VARIABILITY AND PATCH RESOLUTION

    Science.gov (United States)

    Maps of seagrass beds are useful for monitoring estuarine condition, managing habitats, and modeling estuarine processes. We recently developed inexpensive methods for collecting and classifying sidescan sonar (SSS) imagery for seagrass presence in turbid waters as shallow as 1-...

  11. Status of a seagrass ecosystem: An ecologically sensitive wetland habitat from India

    Digital Repository Service at National Institute of Oceanography (India)

    Jagtap, T.G.; Komarpant, D.S.; Rodrigues, R.S.

    , and management points of views. In spite of being one of the predominant marine macrophytic floras, surprisingly, seagrasses have not been introduced in plant science studies, even at the university level. Unawareness regarding the functions of seagrasses...

  12. Distribution of algae, seagrasses, and coral communities from Lakshadweep islands, eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Jagtap, T.G.

    Marine algae, seagrasses and coral from the intertidal, lagoon, reef and subtidal regions (up to 22 m depth) at Kavaratti, Agatti, Bangaram and Suheli islands, of Lakshadweep were studied Marine algae and seagrasses were mainly confined...

  13. Patterns of shading tolerance determined from experimental light reduction studies of seagrasses

    Science.gov (United States)

    An extensive review of the experimental literature on seagrass shading evaluated the relationship between experimental light reductions, duration of experiment and seagrass response metrics to determine whether there were consistent statistical patterns. There were highly signif...

  14. Seasonal grazing and food preference of herbivores in a Posidonia oceanica meadow

    Directory of Open Access Journals (Sweden)

    Andrea Peirano

    2001-12-01

    Full Text Available Seasonal grazing of the fish Sarpa salpa (L., the urchin Paracentrotus lividus Lamarck and the isopods Idotea spp. was compared with the C/N ratio of adult and intermediate leaves and epiphytes of Posidonia oceanica (L. Delile, collected at three different depths. Despite seasonal differences in grazing, herbivores showed preferences throughout the year for adult leaves with more epiphyte and higher N contents. The maximum grazing on adult and intermediate leaves was observed in September and in June for fish and in March for urchins, whereas it was irregular for isopods. Grazing by the three herbivores was not related to their preference for leaves or epiphytes, notwithstanding the seasonal differences in their C and N contents. We concluded that herbivores show no preference for food type throughout the year and that seasonal consumption of P. oceanica is related mainly to herbivore behaviour.

  15. Activated carbon derived from marine Posidonia Oceanica for electric energy storage

    Directory of Open Access Journals (Sweden)

    N. Boukmouche

    2014-07-01

    Full Text Available In this paper, the synthesis and characterization of activated carbon from marine Posidonia Oceanica were studied. The activated carbon was prepared by a simple process namely pyrolysis under inert atmosphere. The activated carbon can be used as electrodes for supercapacitor devices. X-ray diffraction result revealed a polycrystalline graphitic structure. While scanning electron microscope investigation showed a layered structure with micropores. The EDS analysis showed that the activated carbon contains the carbon element in high atomic percentage. Electrochemical impedance spectroscopy revealed a capacitive behavior (electrostatic phenomena. The specific capacity per unit area of the electrochemical double layer of activated carbon electrode in sulfuric acid electrolyte was 3.16 F cm−2. Cyclic voltammetry and galvanostatic chronopotentiometry demonstrated that the electrode has excellent electrochemical reversibility. It has been found that the surface capacitance was strongly related to the specific surface area and pore size.

  16. Specificity in Mesograzer-Induced Defences in Seagrasses

    Science.gov (United States)

    Martínez-Crego, Begoña; Arteaga, Pedro; Ueber, Alexandra; Engelen, Aschwin H.; Santos, Rui; Molis, Markus

    2015-01-01

    Grazing-induced plant defences that reduce palatability to herbivores are widespread in terrestrial plants and seaweeds, but they have not yet been reported in seagrasses. We investigated the ability of two seagrass species to induce defences in response to direct grazing by three associated mesograzers. Specifically, we conducted feeding-assayed induction experiments to examine how mesograzer-specific grazing impact affects seagrass induction of defences within the context of the optimal defence theory. We found that the amphipod Gammarus insensibilis and the isopod Idotea chelipes exerted a low-intensity grazing on older blades of the seagrass Cymodocea nodosa, which reflects a weak grazing impact that may explain the lack of inducible defences. The isopod Synischia hectica exerted the strongest grazing impact on C. nodosa via high-intensity feeding on young blades with a higher fitness value. This isopod grazing induced defences in C. nodosa as indicated by a consistently lower consumption of blades previously grazed for 5, 12 and 16 days. The lower consumption was maintained when offered tissues with no plant structure (agar-reconstituted food), but showing a reduced size of the previous grazing effect. This indicates that structural traits act in combination with chemical traits to reduce seagrass palatability to the isopod. Increase in total phenolics but not in C:N ratio and total nitrogen of grazed C. nodosa suggests chemical defences rather than a modified nutritional quality as primarily induced chemical traits. We detected no induction of defences in Zostera noltei, which showed the ability to replace moderate losses of young biomass to mesograzers via compensatory growth. Our study provides the first experimental evidence of induction of defences against meso-herbivory that reduce further consumption in seagrasses. It also emphasizes the relevance of grazer identity in determining the level of grazing impact triggering resistance and compensatory

  17. Specificity in Mesograzer-Induced Defences in Seagrasses.

    Directory of Open Access Journals (Sweden)

    Begoña Martínez-Crego

    Full Text Available Grazing-induced plant defences that reduce palatability to herbivores are widespread in terrestrial plants and seaweeds, but they have not yet been reported in seagrasses. We investigated the ability of two seagrass species to induce defences in response to direct grazing by three associated mesograzers. Specifically, we conducted feeding-assayed induction experiments to examine how mesograzer-specific grazing impact affects seagrass induction of defences within the context of the optimal defence theory. We found that the amphipod Gammarus insensibilis and the isopod Idotea chelipes exerted a low-intensity grazing on older blades of the seagrass Cymodocea nodosa, which reflects a weak grazing impact that may explain the lack of inducible defences. The isopod Synischia hectica exerted the strongest grazing impact on C. nodosa via high-intensity feeding on young blades with a higher fitness value. This isopod grazing induced defences in C. nodosa as indicated by a consistently lower consumption of blades previously grazed for 5, 12 and 16 days. The lower consumption was maintained when offered tissues with no plant structure (agar-reconstituted food, but showing a reduced size of the previous grazing effect. This indicates that structural traits act in combination with chemical traits to reduce seagrass palatability to the isopod. Increase in total phenolics but not in C:N ratio and total nitrogen of grazed C. nodosa suggests chemical defences rather than a modified nutritional quality as primarily induced chemical traits. We detected no induction of defences in Zostera noltei, which showed the ability to replace moderate losses of young biomass to mesograzers via compensatory growth. Our study provides the first experimental evidence of induction of defences against meso-herbivory that reduce further consumption in seagrasses. It also emphasizes the relevance of grazer identity in determining the level of grazing impact triggering resistance and

  18. Seagrass meadows as a globally significant carbonate reservoir

    Science.gov (United States)

    Mazarrasa, I.; Marbà, N.; Lovelock, C. E.; Serrano, O.; Lavery, P. S.; Fourqurean, J. W.; Kennedy, H.; Mateo, M. A.; Krause-Jensen, D.; Steven, A. D. L.; Duarte, C. M.

    2015-08-01

    There has been growing interest in quantifying the capacity of seagrass ecosystems to act as carbon sinks as a natural way of offsetting anthropogenic carbon emissions to the atmosphere. However, most of the efforts have focused on the particulate organic carbon (POC) stocks and accumulation rates and ignored the particulate inorganic carbon (PIC) fraction, despite important carbonate pools associated with calcifying organisms inhabiting the meadows, such as epiphytes and benthic invertebrates, and despite the relevance that carbonate precipitation and dissolution processes have in the global carbon cycle. This study offers the first assessment of the global PIC stocks in seagrass sediments using a synthesis of published and unpublished data on sediment carbonate concentration from 403 vegetated and 34 adjacent un-vegetated sites. PIC stocks in the top 1 m of sediment ranged between 3 and 1660 Mg PIC ha-1, with an average of 654 ± 24 Mg PIC ha-1, exceeding those of POC reported in previous studies by about a factor of 5. Sedimentary carbonate stocks varied across seagrass communities, with meadows dominated by Halodule, Thalassia or Cymodocea supporting the highest PIC stocks, and tended to decrease polewards at a rate of -8 ± 2 Mg PIC ha-1 per degree of latitude (general linear model, GLM; p seagrass meadows, the mean PIC accumulation rate in seagrass sediments is found to be 126.3 ± 31.05 g PIC m-2 yr-1. Based on the global extent of seagrass meadows (177 000 to 600 000 km2), these ecosystems globally store between 11 and 39 Pg of PIC in the top metre of sediment and accumulate between 22 and 75 Tg PIC yr-1, representing a significant contribution to the carbonate dynamics of coastal areas. Despite the fact that these high rates of carbonate accumulation imply CO2 emissions from precipitation, seagrass meadows are still strong CO2 sinks as demonstrated by the comparison of carbon (PIC and POC) stocks between vegetated and adjacent un-vegetated sediments.

  19. Seagrass meadows as a globally significant carbonate reservoir

    KAUST Repository

    Mazarrasa, I.

    2015-03-06

    There has been a growing interest in quantifying the capacity of seagrass ecosystems to act as carbon sinks as a natural way of offsetting anthropogenic carbon emissions to the atmosphere. However, most of the efforts have focused on the organic carbon (POC) stocks and accumulation rates and ignored the inorganic carbon (PIC) fraction, despite important carbonate pools associated with calcifying organisms inhabiting the meadows, such as epiphytes and benthic invertebrates, and despite the relevance that carbonate precipitation and dissolution processes have in the global carbon cycle. This study offers the first assessment of the global PIC stocks in seagrass sediments using a synthesis of published and unpublished data on sediment carbonate concentration from 402 vegetated and 34 adjacent un-vegetated sites. PIC stocks in the top 1 m sediments ranged between 3 and 1660 Mg PIC ha-1, with an average of 654 ± 24 Mg PIC ha-1, exceeding about 5 fold those of POC reported in previous studies. Sedimentary carbonate stocks varied across seagrass communities, with meadows dominated by Halodule, Thalassia or Cymodocea supporting the highest PIC stocks, and tended to decrease polewards at a rate of -8 ± 2 Mg PIC ha-1 degree-1 of latitude (GLM, p < 0.0003). Using PIC concentration and estimates of sediment accretion in seagrass meadows, mean PIC accumulation rates in seagrass sediments is 126.3 ± 0.7 g PIC m-2 y-1. Based on the global extent of seagrass meadows (177 000 to 600 000 km2), these ecosystems globally store between 11 and 39 Pg of PIC in the top meter of sediment and accumulate between 22 and 76 Tg PIC y-1, representing a significant contribution to the carbonate dynamics of coastal areas. Despite that these high rates of carbonate accumulation imply CO2 emissions from precipitation, seagrass meadows are still strong CO2 sinks as demonstrates the comparison of carbon (POC and POC) stocks between vegetated and adjacent un-vegetated sediments.

  20. Turbulent mixing and fluid transport within Florida Bay seagrass meadows

    Science.gov (United States)

    Hansen, Jennifer C. R.; Reidenbach, Matthew A.

    2017-10-01

    Seagrasses serve an important function in the ecology of Florida Bay, providing critical nursery habitat and a food source for a variety of organisms. They also create significant benthic structure that induces drag, altering local hydrodynamics that can influence mixing and nutrient dynamics. Thalassia testudinum seagrass meadows were investigated to determine how shoot density and morphometrics alter local wave conditions, the generation of turbulence, and fluid exchange above and within the canopy. Sparsely vegetated and densely vegetated meadows were monitored, with shoot densities of 259 ± 26 and 484 ± 78 shoots m-2, respectively. The temporal and spatial structure of velocity and turbulence were measured using acoustic Doppler velocimeters and an in situ particle image velocimetry (PIV) system positioned both above and within the seagrass canopy. The retention of fluid within the canopy was determined by examining e-folding times calculated from the concentration curves of dye plumes released within the seagrass canopy. Results show that a shear layer with an inflection point develops at the top of the seagrass canopy, which generates instabilities that impart turbulence into the seagrass meadow. Compared to the overlying water column, turbulence was enhanced within the sparse canopy due to flow interaction with the seagrass blades, but reduced within the dense canopy. Wave generated oscillatory motion penetrated deeper into the canopy than unidirectional currents, enhancing fluid exchange. Both shoot density and the relative magnitude of wave- versus current-driven flow conditions were found to be important controls on turbulent exchange of water masses across the canopy-water interface.

  1. Mapping of seagrass meadows from the Lakshadweep Islands (India), using aerial photographs

    Digital Repository Service at National Institute of Oceanography (India)

    Jagtap, T.G.; Inamdar, S.N.

    Seagrass meadows from the Lakshadweep Islands were mapped with the help of black and white aerial photographs. A maximum of 40 ha seagrass cover was estimated in the lagoon of Minicoy, followEd. by Kavaratti (43 ha.). The total seagrass cover from...

  2. Utilization of seagrass habitats by juvenile groupers and snappers in Banten Bay, Banten Province, Indonesia

    NARCIS (Netherlands)

    Nuraini, S.; Carballo, E.C.; Densen, van W.L.T.; Machiels, M.A.M.; Lindeboom, H.J.; Nagelkerke, L.A.J.

    2007-01-01

    Coastal development in Banten Bay, Indonesia, decreased seagrass coverage to only 1.5% of its surface area. We investigated the importance of seagrass as habitat for juvenile groupers (Serranidae) and snappers (Lutjanidae), by performing beam trawl hauls on a weekly basis in two seagrass locations a

  3. Mass-Balance Constraints on Nutrient Cycling in Tropical Seagrass Beds

    NARCIS (Netherlands)

    Erftemeijer, P.L.A.; Middelburg, J.J.

    1995-01-01

    A relatively simple mass balance model is presented to study the cycling of nutrients (nitrogen and phosphorus) in tropical seagrass beds. The model is based on quantitative data on nutrient availability, seagrass primary production, community oxygen metabolism, seagrass tissue nutrient contents,

  4. First record of a Caribbean green turtle (Chelonia mydas) grazing on invasive seagrass (Halophila stipulacea)

    NARCIS (Netherlands)

    Becking, Leontine E.; van Bussel, Tineke C. J. M.; Debrot, Adolphe O.; Christianen, Marjolijn J. A.

    2014-01-01

    From Bonaire, we here provide the first documented case of the green turtle feeding on the invasive seagrass, Halophila stipulacea, in the Caribbean. The seagrass is rapidly invading existing seagrass meadows and altering key foraging habitat of this endangered marine reptile throughout the eastern

  5. First record of a Caribbean green turtle (Chelonia mydas) grazing on invasive seagrass (Halophila stipulacea)

    NARCIS (Netherlands)

    Becking, Leontine E.; van Bussel, Tineke C. J. M.; Debrot, Adolphe O.; Christianen, Marjolijn J. A.

    2014-01-01

    From Bonaire, we here provide the first documented case of the green turtle feeding on the invasive seagrass, Halophila stipulacea, in the Caribbean. The seagrass is rapidly invading existing seagrass meadows and altering key foraging habitat of this endangered marine reptile throughout the eastern

  6. Posidonia oceanica as a Renewable Lignocellulosic Biomass for the Synthesis of Cellulose Acetate and Glycidyl Methacrylate Grafted Cellulose

    Directory of Open Access Journals (Sweden)

    Elena Vismara

    2013-05-01

    Full Text Available High-grade cellulose (97% α-cellulose content of 48% crystallinity index was extracted from the renewable marine biomass waste Posidonia oceanica using H2O2 and organic peracids following an environmentally friendly and chlorine-free process. This cellulose appeared as a new high-grade cellulose of waste origin quite similar to the high-grade cellulose extracted from more noble starting materials like wood and cotton linters. The benefits of α-cellulose recovery from P. oceanica were enhanced by its transformation into cellulose acetate CA and cellulose derivative GMA-C. Fully acetylated CA was prepared by conventional acetylation method and easily transformed into a transparent film. GMA-C with a molar substitution (MS of 0.72 was produced by quenching Fenton’s reagent (H2O2/FeSO4 generated cellulose radicals with GMA. GMA grafting endowed high-grade cellulose from Posidonia with adsorption capability. GMA-C removes β-naphthol from water with an efficiency of 47%, as measured by UV-Vis spectroscopy. After hydrolysis of the glycidyl group to glycerol group, the modified GMA-C was able to remove p-nitrophenol from water with an efficiency of 92%, as measured by UV-Vis spectroscopy. α-cellulose and GMA-Cs from Posidonia waste can be considered as new materials of potential industrial and environmental interest.

  7. Impact of mooring activities on carbon stocks in seagrass meadows

    Science.gov (United States)

    Serrano, O.; Ruhon, R.; Lavery, P. S.; Kendrick, G. A.; Hickey, S.; Masqué, P.; Arias-Ortiz, A.; Steven, A.; Duarte, C. M.

    2016-03-01

    Boating activities are one of the causes that threaten seagrass meadows and the ecosystem services they provide. Mechanical destruction of seagrass habitats may also trigger the erosion of sedimentary organic carbon (Corg) stocks, which may contribute to increasing atmospheric CO2. This study presents the first estimates of loss of Corg stocks in seagrass meadows due to mooring activities in Rottnest Island, Western Australia. Sediment cores were sampled from seagrass meadows and from bare but previously vegetated sediments underneath moorings. The Corg stores have been compromised by the mooring deployment from 1930s onwards, which involved both the erosion of existing sedimentary Corg stores and the lack of further accumulation of Corg. On average, undisturbed meadows had accumulated ~6.4 Kg Corg m-2 in the upper 50 cm-thick deposits at a rate of 34 g Corg m-2 yr-1. The comparison of Corg stores between meadows and mooring scars allows us to estimate a loss of 4.8 kg Corg m-2 in the 50 cm-thick deposits accumulated over ca. 200 yr as a result of mooring deployments. These results provide key data for the implementation of Corg storage credit offset policies to avoid the conversion of seagrass ecosystems and contribute to their preservation.

  8. Impact of mooring activities on carbon stocks in seagrass meadows

    KAUST Repository

    Serrano, O.

    2016-03-16

    Boating activities are one of the causes that threaten seagrass meadows and the ecosystem services they provide. Mechanical destruction of seagrass habitats may also trigger the erosion of sedimentary organic carbon (Corg) stocks, which may contribute to increasing atmospheric CO2. This study presents the first estimates of loss of Corg stocks in seagrass meadows due to mooring activities in Rottnest Island, Western Australia. Sediment cores were sampled from seagrass meadows and from bare but previously vegetated sediments underneath moorings. The Corg stores have been compromised by the mooring deployment from 1930s onwards, which involved both the erosion of existing sedimentary Corg stores and the lack of further accumulation of Corg. On average, undisturbed meadows had accumulated ~6.4 Kg Corg m−2 in the upper 50 cm-thick deposits at a rate of 34 g Corg m−2 yr−1. The comparison of Corg stores between meadows and mooring scars allows us to estimate a loss of 4.8 kg Corg m−2 in the 50 cm-thick deposits accumulated over ca. 200 yr as a result of mooring deployments. These results provide key data for the implementation of Corg storage credit offset policies to avoid the conversion of seagrass ecosystems and contribute to their preservation.

  9. Florida seagrass habitat evaluation: A comparative survey for chemical quality

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Michael A. [U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, 1 Sabine Island Drive, Gulf Breeze, FL 32561 (United States)]. E-mail: lewis.michael@epa.gov; Dantin, Darrin D. [U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, 1 Sabine Island Drive, Gulf Breeze, FL 32561 (United States); Chancy, Cynthia A. [U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, 1 Sabine Island Drive, Gulf Breeze, FL 32561 (United States); Abel, Kathryn C. [Department of Biological Sciences, University of West Florida, Pensacola, FL 32514 (United States); Lewis, Christopher G. [Department of Water and Soil Science, University of Florida, Gainesville, FL 32103 (United States)

    2007-03-15

    Contaminant concentrations were determined for media associated with 13 Florida seagrass beds. Concentrations of 10 trace metals were more commonly detected in surface water, sediment and two seagrass species than PAHs, pesticides and PCBs. Concentrations of copper and arsenic in surface water exceeded Florida aquatic life criteria more frequently than other trace elements. Total organic carbon, mercury, chromium, zinc, total chlordane, total PAHs, total PCBs, DDD and DDE were significantly greater in seagrass-rooted sediments than adjacent non-vegetated sediments. Total DDT, DDD, DDE, total chlordane, arsenic, copper and nickel exceeded proposed sediment quality guidelines at six of 13 grass beds. Pesticides, PAHs, and PCBs were below detection in seagrass tissues. Mercury, cadmium, nickel, lead and silver were detected in 50% or more of the tissues for Thalassia testudinum (turtle grass) and Halodule wrightii (shoal grass). Spatial, interspecific and tissue differences were usually an order of magnitude or less. - Some anthropogenic contaminants were prevalent in seagrass and their rooted sediments but the biological significance is unknown.

  10. Seagrass species distribution, density and coverage at Panggang Island, Jakarta

    Science.gov (United States)

    Wahab, Iswandi; Madduppa, Hawis; Kawaroe, Mujizat

    2017-01-01

    This study aimed to assess species distribution, density and coverage of seagrass in Panggang Island, within Kepulauan Seribu Marine National Park, northern Jakarta. Seagrass sampling was conducted between March to April 2016 at three observation stations in the West, East, and South of Panggang Island. A total of 6 seagrass species was recorded during sampling period, including Cymodocea rotundata, C. serulata, Halodule uninervis, Syiringodium isoetifolium, Enhalus acoroides, and Thalassia hempricii. All species were observed in the South station, while in the West and East station found only three species (C. rotundata, E. acoroides, and T. hemprichii). While, C. rotundata and T. hemprichii were observed at all station. The highest density was observed for C. rotundata (520 ind/m2) and for T. hempricii (619 ind/m2) in the West station and South Station, respectively. The lowest density was observed in South Station for C. serulata (18 ind/m2), Halodule uninervis (20 ind/m2), and Syiringodium isoetifolium (15 ind/m2). Seagrass coverage of Thalassia hempricii was the highest (43.60%) and the lowest observed at Syiringodium isoetifolium (0.40%). This could be basic information for the management of seagrass ecosystem in the Kepulauan Seribu Marine National Park.

  11. Impact of mooring activities on carbon stocks in seagrass meadows.

    Science.gov (United States)

    Serrano, O; Ruhon, R; Lavery, P S; Kendrick, G A; Hickey, S; Masqué, P; Arias-Ortiz, A; Steven, A; Duarte, C M

    2016-03-16

    Boating activities are one of the causes that threaten seagrass meadows and the ecosystem services they provide. Mechanical destruction of seagrass habitats may also trigger the erosion of sedimentary organic carbon (Corg) stocks, which may contribute to increasing atmospheric CO2. This study presents the first estimates of loss of Corg stocks in seagrass meadows due to mooring activities in Rottnest Island, Western Australia. Sediment cores were sampled from seagrass meadows and from bare but previously vegetated sediments underneath moorings. The Corg stores have been compromised by the mooring deployment from 1930s onwards, which involved both the erosion of existing sedimentary Corg stores and the lack of further accumulation of Corg. On average, undisturbed meadows had accumulated ~6.4 Kg Corg m(-2) in the upper 50 cm-thick deposits at a rate of 34 g Corg m(-2) yr(-1). The comparison of Corg stores between meadows and mooring scars allows us to estimate a loss of 4.8 kg Corg m(-2) in the 50 cm-thick deposits accumulated over ca. 200 yr as a result of mooring deployments. These results provide key data for the implementation of Corg storage credit offset policies to avoid the conversion of seagrass ecosystems and contribute to their preservation.

  12. ESTIMATION OF SEAGRASS COVERAGE BY DEPTH INVARIANT INDICES ON QUICKBIRD IMAGERY

    Directory of Open Access Journals (Sweden)

    Muhammad Anshar Amran

    2010-01-01

    Full Text Available Management of seagrass ecosystem requires availability of information on the actual condition of seagrass coverage. Remote sensing technology for seagrass mapping has been used to detect the presence of seagrass coverage, but so far no information on the condition of seagrass could be obtained. Therefore, a research is required using remote sensing imagery to obtain information on the condition of seagrass coverage.The aim of this research is to formulate mathematical relationship between seagrass coverage and depth invariant indices on Quickbird imagery. Transformation was done on multispectral bands which could detect sea floor objects that are in the region of blue, green and red bands.The study areas covered are the seas around Barranglompo Island and Barrangcaddi Island, westward of Makassar city, Indonesia. Various seagrass coverages were detected within the region under study.Mathematical relationship between seagrass coverage and depth invariant indices was obtained by multiple linear regression method. Percentage of seagrass coverage (C was obtained by transformation of depth invariant indices (Xij on Quickbird imagery, with transformation equation as follows:C = 19.934 – 63.347 X12 + 23.239 X23.A good accuracy of 75% for the seagrass coverage was obtained by transformation of depth invariant indices (Xij on Quickbird imagery.

  13. Trophic cascades on the edge: fostering seagrass resilience via a novel pathway.

    Science.gov (United States)

    Hughes, Brent B; Hammerstrom, Kamille K; Grant, Nora E; Hoshijima, Umi; Eby, Ron; Wasson, Kerstin

    2016-09-01

    Despite widespread degradation, some coastal ecosystems display remarkable resilience. For seagrasses, a century-old paradigm has implicated macroalgal blooms stimulated by anthropogenic nutrient, loading as a primary driver of seagrass decline, yet relatively little attention has been given to drivers of seagrass resilience. In Elkhorn Slough, CA, an estuarine system characterized by extreme anthropogenic nutrient loading and macroalgal (Ulva spp.) blooms, seagrass (Zostera marina) beds have recovered concurrent with colonization of the estuary by top predators, sea otters (Enhydra lutris). Here, we follow up on the results of a previous experiment at the seagrass interior, showing how sea otters can generate a trophic cascade that promotes seagrass. We conducted an experiment and constructed structural equation models to determine how sea otters, through a trophic cascade, might affect the edge of seagrass beds where expansion occurs. We found that at the edge, sea otters promoted both seagrass and ephemeral macroalgae, with the latter contributing beneficial grazers to the seagrass. The surprising results that sea otters promote two potentially competing vegetation types, and a grazer assemblage at their boundary provides a mechanism by which seagrasses can expand in eutrophic environments, and contributes to a growing body of literature demonstrating that ephemeral macroalgae are not always negatively associated with seagrass. Our results highlight the potential for top predator recovery to enhance ecosystem resilience to anthropogenic alterations through several cascading mechanisms.

  14. Photorespiration and carbon limitation determine productivity in temperate seagrasses.

    Directory of Open Access Journals (Sweden)

    Pimchanok Buapet

    Full Text Available The gross primary productivity of two seagrasses, Zostera marina and Ruppia maritima, and one green macroalga, Ulva intestinalis, was assessed in laboratory and field experiments to determine whether the photorespiratory pathway operates at a substantial level in these macrophytes and to what extent it is enhanced by naturally occurring shifts in dissolved inorganic carbon (DIC and O2 in dense vegetation. To achieve these conditions in laboratory experiments, seawater was incubated with U. intestinalis in light to obtain a range of higher pH and O2 levels and lower DIC levels. Gross photosynthetic O2 evolution was then measured in this pretreated seawater (pH, 7.8-9.8; high to low DIC:O2 ratio at both natural and low O2 concentrations (adjusted by N2 bubbling. The presence of photorespiration was indicated by a lower gross O2 evolution rate under natural O2 conditions than when O2 was reduced. In all three macrophytes, gross photosynthetic rates were negatively affected by higher pH and lower DIC. However, while both seagrasses exhibited significant photorespiratory activity at increasing pH values, the macroalga U. intestinalis exhibited no such activity. Rates of seagrass photosynthesis were then assessed in seawater collected from the natural habitats (i.e., shallow bays characterized by high macrophyte cover and by low DIC and high pH during daytime and compared with open baymouth water conditions (where seawater DIC is in equilibrium with air, normal DIC, and pH. The gross photosynthetic rates of both seagrasses were significantly higher when incubated in the baymouth water, indicating that these grasses can be significantly carbon limited in shallow bays. Photorespiration was also detected in both seagrasses under shallow bay water conditions. Our findings indicate that natural carbon limitations caused by high community photosynthesis can enhance photorespiration and cause a significant decline in seagrass primary production in shallow

  15. Photorespiration and carbon limitation determine productivity in temperate seagrasses.

    Science.gov (United States)

    Buapet, Pimchanok; Rasmusson, Lina M; Gullström, Martin; Björk, Mats

    2013-01-01

    The gross primary productivity of two seagrasses, Zostera marina and Ruppia maritima, and one green macroalga, Ulva intestinalis, was assessed in laboratory and field experiments to determine whether the photorespiratory pathway operates at a substantial level in these macrophytes and to what extent it is enhanced by naturally occurring shifts in dissolved inorganic carbon (DIC) and O2 in dense vegetation. To achieve these conditions in laboratory experiments, seawater was incubated with U. intestinalis in light to obtain a range of higher pH and O2 levels and lower DIC levels. Gross photosynthetic O2 evolution was then measured in this pretreated seawater (pH, 7.8-9.8; high to low DIC:O2 ratio) at both natural and low O2 concentrations (adjusted by N2 bubbling). The presence of photorespiration was indicated by a lower gross O2 evolution rate under natural O2 conditions than when O2 was reduced. In all three macrophytes, gross photosynthetic rates were negatively affected by higher pH and lower DIC. However, while both seagrasses exhibited significant photorespiratory activity at increasing pH values, the macroalga U. intestinalis exhibited no such activity. Rates of seagrass photosynthesis were then assessed in seawater collected from the natural habitats (i.e., shallow bays characterized by high macrophyte cover and by low DIC and high pH during daytime) and compared with open baymouth water conditions (where seawater DIC is in equilibrium with air, normal DIC, and pH). The gross photosynthetic rates of both seagrasses were significantly higher when incubated in the baymouth water, indicating that these grasses can be significantly carbon limited in shallow bays. Photorespiration was also detected in both seagrasses under shallow bay water conditions. Our findings indicate that natural carbon limitations caused by high community photosynthesis can enhance photorespiration and cause a significant decline in seagrass primary production in shallow waters.

  16. Seagrass Health Modeling and Prediction with NASA Science Data

    Science.gov (United States)

    Robinson, Harold D.; Easson, Greg; Slattery, Marc; Anderson, Daniel; Blonski, Slawomir; DeCurtins, Robert; Underwood, Lauren

    2010-01-01

    Previous research has demonstrated that MODIS data products can be used as inputs into the seagrass productivity model developed by Fong and Harwell (1994). To further explore this use to predict seagrass productivity, Moderate Resolution Imaging Spectroradiometer (MODIS) custom data products, including Sea Surface Temperature, Light Attenuation, and Chlorophyll-a have been created for use as model parameter inputs. Coastal researchers can use these MODIS data products and model results in conjunction with historical and daily assessment of seagrass conditions to assess variables that affect the productivity of the seagrass beds. Current monitoring practices involve manual data collection (typically on a quarterly basis) and the data is often insufficient for evaluating the dynamic events that influence seagrass beds. As part of a NASA-funded research grant, the University of Mississippi, is working with researchers at NASA and Radiance Technologies to develop methods to deliver MODIS derived model output for the northern Gulf of Mexico (GOM) to coastal and environmental managers. The result of the project will be a data portal that provides access to MODIS data products and model results from the past 5 years, that includes an automated process to incorporate new data as it becomes available. All model parameters and final output will be available through the use National Oceanic and Atmospheric Administration?s (NOAA) Environmental Research Divisions Data Access Program (ERDDAP) tools as well as viewable using Thematic Realtime Environmental Distributed Data Services (THREDDS) and the Integrated Data Viewer (IDV). These tools provide the ability to create raster-based time sequences of model output and parameters as well as create graphs of model parameters versus time. This tool will provide researchers and coastal managers the ability to analyze the model inputs so that the factors influencing a change in seagrass productivity can be determined over time.

  17. Dugong dugon feeding in tropical Australian seagrass meadows: implications for conservation planning

    Directory of Open Access Journals (Sweden)

    Samantha J. Tol

    2016-07-01

    Full Text Available Dugongs (Dugong dugon are listed as vulnerable to extinction due to rapid population reductions caused in part by loss of seagrass feeding meadows. Understanding dugong feeding behaviour in tropical Australia, where the majority of dugongs live, will assist conservation strategies. We examined whether feeding patterns in intertidal seagrass meadows in tropical north-eastern Australia were related to seagrass biomass, species composition and/or nitrogen content. The total biomass of each seagrass species removed by feeding dugongs was measured and compared to its relative availability. Nitrogen concentrations were also determined for each seagrass species present at the sites. Dugongs consumed seagrass species in proportion to their availability, with biomass being the primary determining factor. Species composition and/or nitrogen content influenced consumption to a lesser degree. Conservation plans focused on protecting high biomass intertidal seagrass meadows are likely to be most effective at ensuring the survival of dugong in tropical north-eastern Australia.

  18. The influence of wave energy and sediment transport on seagrass distribution

    Science.gov (United States)

    Stevens, Andrew W.; Lacy, Jessica R.

    2012-01-01

    A coupled hydrodynamic and sediment transport model (Delft3D) was used to simulate the water levels, waves, and currents associated with a seagrass (Zostera marina) landscape along a 4-km stretch of coast in Puget Sound, WA, USA. A hydroacoustic survey of seagrass percent cover and nearshore bathymetry was conducted, and sediment grain size was sampled at 53 locations. Wave energy is a primary factor controlling seagrass distribution at the site, accounting for 73% of the variability in seagrass minimum depth and 86% of the variability in percent cover along the shallow, sandy portions of the coast. A combination of numerical simulations and a conceptual model of the effect of sea-level rise on the cross-shore distribution of seagrass indicates that the area of seagrass habitat may initially increase and that wave dynamics are an important factor to consider in predicting the effect of sea-level rise on seagrass distributions in wave-exposed areas.

  19. Impact of pond aquaculture effluents on seagrass performance in NE Hainan, tropical China.

    Science.gov (United States)

    Herbeck, Lucia S; Sollich, Miriam; Unger, Daniela; Holmer, Marianne; Jennerjahn, Tim C

    2014-08-15

    The impact of pond aquaculture effluents on the distribution and performance of seagrasses was examined in NE Hainan, tropical China. Samples were taken along transects in three back-reef areas with different extent of aquaculture production in their hinterland. High δ(15)N in seagrass leaves and epiphytes (6-9‰) similar to values in pond effluents documented aquaculture as dominant nitrogen source in the back-reefs with decreasing impact with distance from shore. Seagrass species abundance, shoot density and biomass were lower and concentrations of nutrients, chlorophyll and suspended matter were higher at nearshore sites with high and moderate pond abundance than at the control site. High epiphyte loads and low δ(34)S in seagrass leaves suggest temporal shading and sulphide poisoning of the nearshore seagrasses. Observed gradients in environmental parameters and seagrass performance indicate that the distance from the pond outlets and size of the adjacent pond agglomeration are major determinants of seagrass degradation.

  20. A preliminary evaluation of wave attenuation by four species of seagrass

    Science.gov (United States)

    Fonseca, Mark S.; Cahalan, Jennifer A.

    1992-12-01

    Seagrasses are able to modify current flow and sediment composition, yet little information exists describing their effect on waves. Four species of seagrass, Halodule wrightii, Syringodium filiforme, Thalassia testudinum and Zostera marina were evaluated for their ability to reduce wave energy under various combinations of shoot density and water depths over a 1 m test section in a wave tank. Percent wave energy reduction per meter of seagrass bed equaled 40% when the length of these seagrasses was similar to the water depth. Seagrasses are approximately equal to saltmarshes in reducing wave energy on a unit distance basis, but only when water depth is scaled to plant size. When seagrass beds occur as broad, shallow meadows, the influence of seagrasses on wave energy will be substantial.

  1. Quantifying and modelling the carbon sequestration capacity of seagrass meadows--a critical assessment.

    Science.gov (United States)

    Macreadie, P I; Baird, M E; Trevathan-Tackett, S M; Larkum, A W D; Ralph, P J

    2014-06-30

    Seagrasses are among the planet's most effective natural ecosystems for sequestering (capturing and storing) carbon (C); but if degraded, they could leak stored C into the atmosphere and accelerate global warming. Quantifying and modelling the C sequestration capacity is therefore critical for successfully managing seagrass ecosystems to maintain their substantial abatement potential. At present, there is no mechanism to support carbon financing linked to seagrass. For seagrasses to be recognised by the IPCC and the voluntary C market, standard stock assessment methodologies and inventories of seagrass C stocks are required. Developing accurate C budgets for seagrass meadows is indeed complex; we discuss these complexities, and, in addition, we review techniques and methodologies that will aid development of C budgets. We also consider a simple process-based data assimilation model for predicting how seagrasses will respond to future change, accompanied by a practical list of research priorities.

  2. Dugong dugon feeding in tropical Australian seagrass meadows: implications for conservation planning.

    Science.gov (United States)

    Tol, Samantha J; Coles, Rob G; Congdon, Bradley C

    2016-01-01

    Dugongs (Dugong dugon) are listed as vulnerable to extinction due to rapid population reductions caused in part by loss of seagrass feeding meadows. Understanding dugong feeding behaviour in tropical Australia, where the majority of dugongs live, will assist conservation strategies. We examined whether feeding patterns in intertidal seagrass meadows in tropical north-eastern Australia were related to seagrass biomass, species composition and/or nitrogen content. The total biomass of each seagrass species removed by feeding dugongs was measured and compared to its relative availability. Nitrogen concentrations were also determined for each seagrass species present at the sites. Dugongs consumed seagrass species in proportion to their availability, with biomass being the primary determining factor. Species composition and/or nitrogen content influenced consumption to a lesser degree. Conservation plans focused on protecting high biomass intertidal seagrass meadows are likely to be most effective at ensuring the survival of dugong in tropical north-eastern Australia.

  3. Monitoring in the Western Pacific region shows evidence of seagrass decline in line with global trends.

    Science.gov (United States)

    Short, Frederick T; Coles, Robert; Fortes, Miguel D; Victor, Steven; Salik, Maxwell; Isnain, Irwan; Andrew, Jay; Seno, Aganto

    2014-06-30

    Seagrass systems of the Western Pacific region are biodiverse habitats, providing vital services to ecosystems and humans over a vast geographic range. SeagrassNet is a worldwide monitoring program that collects data on seagrass habitats, including the ten locations across the Western Pacific reported here where change at various scales was rapidly detected. Three sites remote from human influence were stable. Seagrasses declined largely due to increased nutrient loading (4 sites) and increased sedimentation (3 sites), the two most common stressors of seagrass worldwide. Two sites experienced near-total loss from of excess sedimentation, followed by partial recovery once sedimentation was reduced. Species shifts were observed at every site with recovering sites colonized by pioneer species. Regulation of watersheds is essential if marine protected areas are to preserve seagrass meadows. Seagrasses in the Western Pacific experience stress due to human impacts despite the vastness of the ocean area and low development pressures.

  4. Protecting the hand that feeds us: seagrass (Zostera marina) serves as commercial juvenile fish habitat.

    Science.gov (United States)

    Bertelli, Chiara M; Unsworth, Richard K F

    2014-06-30

    Although fisheries are of major economic and food security importance we still know little about specific juvenile habitats that support such production. This is a major issue given the degradation to and lack of protection afforded to potential juvenile habitats such as seagrass meadows. In the present study we investigate the role of seagrass in supporting juvenile fish of commercial value. By assessing seagrass relative to adjacent sand we determined the presence of abundant juvenile fish. Nine commercial species were recorded and the most abundant of these were Plaice, Pollock and Herring. We provide the first quantitative evidence of the presence of juvenile fish of commercial value in seagrass surrounding Great Britain. Although the species that we found in seagrass as juveniles are not obligate seagrass users the resources that seagrass meadows offer to these fish provide significant long-term fitness benefits, potentially enhancing the whole population.

  5. Courage under fire: seagrass persistence adjacent to a highly urbanised city-state.

    Science.gov (United States)

    Yaakub, Siti Maryam; McKenzie, Len J; Erftemeijer, Paul L A; Bouma, Tjeerd; Todd, Peter A

    2014-06-30

    Due to increasing development Southeast Asia's coastlines are undergoing massive changes, but the associated impacts on marine habitats are poorly known. Singapore, a densely populated island city-state, is a quintessential example of coastal modification that has resulted in the (hitherto undocumented) loss of seagrass. We reconstructed the historic extent and diversity of local seagrass meadows through herbarium records and backwards extrapolation from contemporary seagrass locations. We also determined the current status of seagrass meadows using long-term monitoring data and identified the main threats to their presence in Singapore. Results show that, even though ∼45% of seagrass has been lost during the last five decades, species diversity remains stable. The main cause of seagrass loss was, and continues to be, land reclamation. We conclude that strict controls on terrestrial runoff and pollution have made it possible for seagrass to persist adjacent to this highly urbanised city-state.

  6. Local Knowledge and Conservation of Seagrasses in the Tamil Nadu State of India

    Directory of Open Access Journals (Sweden)

    Newmaster AF

    2011-11-01

    Full Text Available Abstract Local knowledge systems are not considered in the conservation of fragile seagrass marine ecosystems. In fact, little is known about the utility of seagrasses in local coastal communities. This is intriguing given that some local communities rely on seagrasses to sustain their livelihoods and have relocated their villages to areas with a rich diversity and abundance of seagrasses. The purpose of this study is to assist in conservation efforts regarding seagrasses through identifying Traditional Ecological Knowledge (TEK from local knowledge systems of seagrasses from 40 coastal communities along the eastern coast of India. We explore the assemblage of scientific and local traditional knowledge concerning the 1. classification of seagrasses (comparing scientific and traditional classification systems, 2. utility of seagrasses, 3. Traditional Ecological Knowledge (TEK of seagrasses, and 4. current conservation efforts for seagrass ecosystems. Our results indicate that local knowledge systems consist of a complex classification of seagrass diversity that considers the role of seagrasses in the marine ecosystem. This fine-scaled ethno-classification gives rise to five times the number of taxa (10 species = 50 local ethnotaxa, each with a unique role in the ecosystem and utility within coastal communities, including the use of seagrasses for medicine (e.g., treatment of heart conditions, seasickness, etc., food (nutritious seeds, fertilizer (nutrient rich biomass and livestock feed (goats and sheep. Local communities are concerned about the loss of seagrass diversity and have considerable local knowledge that is valuable for conservation and restoration plans. This study serves as a case study example of the depth and breadth of local knowledge systems for a particular ecosystem that is in peril. Key words: local health and nutrition, traditional ecological knowledge (TEK, conservation and natural resources management, consensus

  7. Local knowledge and conservation of seagrasses in the Tamil Nadu state of India.

    Science.gov (United States)

    Newmaster, A F; Berg, K J; Ragupathy, S; Palanisamy, M; Sambandan, K; Newmaster, S G

    2011-11-23

    Local knowledge systems are not considered in the conservation of fragile seagrass marine ecosystems. In fact, little is known about the utility of seagrasses in local coastal communities. This is intriguing given that some local communities rely on seagrasses to sustain their livelihoods and have relocated their villages to areas with a rich diversity and abundance of seagrasses. The purpose of this study is to assist in conservation efforts regarding seagrasses through identifying Traditional Ecological Knowledge (TEK) from local knowledge systems of seagrasses from 40 coastal communities along the eastern coast of India. We explore the assemblage of scientific and local traditional knowledge concerning the 1. classification of seagrasses (comparing scientific and traditional classification systems), 2. utility of seagrasses, 3. Traditional Ecological Knowledge (TEK) of seagrasses, and 4. current conservation efforts for seagrass ecosystems. Our results indicate that local knowledge systems consist of a complex classification of seagrass diversity that considers the role of seagrasses in the marine ecosystem. This fine-scaled ethno-classification gives rise to five times the number of taxa (10 species = 50 local ethnotaxa), each with a unique role in the ecosystem and utility within coastal communities, including the use of seagrasses for medicine (e.g., treatment of heart conditions, seasickness, etc.), food (nutritious seeds), fertilizer (nutrient rich biomass) and livestock feed (goats and sheep). Local communities are concerned about the loss of seagrass diversity and have considerable local knowledge that is valuable for conservation and restoration plans. This study serves as a case study example of the depth and breadth of local knowledge systems for a particular ecosystem that is in peril.

  8. Geomechanical and anisotropic acoustic properties of Lower Jurassic Posidonia shales from Whitby (UK)

    Science.gov (United States)

    Zhubayev, Alimzhan; Houben, Maartje; Smeulders, David; Barnhoorn, Auke

    2014-05-01

    The Posidonia Shale Formation (PSF) is one of the possible resource shales for unconventional gas in Northern Europe and currently is of great interest to hydrocarbon exploration and production. Due to low permeability of shales, economically viable production requires hydraulic fracturing of the reservoir. The design of hydrofractures requires an estimate of stress state within the reservoir and geomechanical properties such as Young's modulus and Poisson's ratio. Shales are often highly anisotropic and the models which neglect shale anisotropy may fail to predict the behaviour of hydrofractures. Seismic attenuation anisotropy, on the other hand, can play a key role in quantitative rock characterization. Where the attenuation anisotropy can potentially be linked to anisotropic permeability of shales, its fluid/gas saturation and preferred development of anisotropic fracture orientations. In this research, by utilizing the so-called Thomsen's notations, the elastic anisotropy of our (fractured and unfractured) shales has been investigated using a pulse transmission technique in the ultrasonic frequency range (0.3-1 MHz). Assuming transverse isotropy of the shales, and taking the axis x3 as the axis of rotational symmetry, directional Young's moduli and Poisson's ratios were obtained. The Young's modulus measured parallel to bedding (E1) is found to be larger than the Young's modulus measured orthogonal to bedding (E3). In case of the Poisson's ratios, we found that ν31 is larger than ν12, where νijrelates elastic strain in xj direction to stress applied in xi direction. Finally, attenuation anisotropy in dry and layer-parallel fractured Posidonia shale samples has been studied in the same frequency range. The attenuation of compressional (QP-1) and shear (QS-1) waves increases substantially with a macro (or wavelength) fracture introduction, especially for P and S waves propagating orthogonal to the bedding. In non-fractured and fractured dry shales, QP-1 is

  9. Diversity of European seagrass indicators. Patterns within and across regions

    DEFF Research Database (Denmark)

    Krause-Jensen, Dorte; Marbà, N.; Alcoverro, T.;

    as by differences in habitat conditions and associated community types but also seems to be determined by tradition. We encourage an evaluation of seagrass indicators on the basis of their responses to pressures in space and time and their associated uncertainty in order to identify the most suitable indicators...

  10. Seagrass biofilm communities at a naturally CO2 -rich vent.

    Science.gov (United States)

    Hassenrück, Christiane; Hofmann, Laurie C; Bischof, Kai; Ramette, Alban

    2015-06-01

    Seagrass meadows are a crucial component of tropical marine reef ecosystems. Seagrass plants are colonized by a multitude of epiphytic organisms that contribute to broadening the ecological role of seagrasses. To better understand how environmental changes like ocean acidification might affect epiphytic assemblages, the microbial community composition of the epiphytic biofilm of Enhalus acroides was investigated at a natural CO2 vent in Papua New Guinea using molecular fingerprinting and next-generation sequencing of 16S and 18S rRNA genes. Both bacterial and eukaryotic epiphytes formed distinct communities at the CO2 -impacted site compared with the control site. This site-related CO2 effect was also visible in the succession pattern of microbial epiphytes. We further found an increased relative sequence abundance of bacterial types associated with coral diseases at the CO2 -impacted site (Fusobacteria, Thalassomonas), whereas eukaryotes such as certain crustose coralline algae commonly related to healthy reefs were less diverse. These trends in the epiphytic community of E. acroides suggest a potential role of seagrasses as vectors of coral pathogens and may support previous predictions of a decrease in reef health and prevalence of diseases under future ocean acidification scenarios. © 2015 The Authors. Environmental Microbiology Reports published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. Seagrass productivity: the effect of light on carbon uptake

    Energy Technology Data Exchange (ETDEWEB)

    Williams, S.L.; McRoy, C.P.

    1982-08-01

    Productivity, as estimated by /sup 14/C uptake, was determined as a function of irradiance for six North American seagrasses (Thalassia testudinum Banks ex. Koenig, Syringodium filiforme Kuetz, Halodule wrightii Aschers., Halophila engelmanni Aschers., Phyllospadix scouleri Hook and Ruppia maritima L.s.l.) from temperature, subtropical and tropical environments. Light versus productivity curves were typical of those of aquatic plants. Seagrasses achieved high rates of uptake (up to 17.31 mg C (g dry)-1 h-1) and exhibited high saturation irradiances (greater than or equal to 40% surface irradiance). Within each environment half-saturation and saturation irradiances were similar, indicating no competition for light in the production systems of the various species. Between environments maximum productivity and saturation irradiances changed as a function of the differing irradiance. When rates were normalized for ambient irradiance, there were no differences in maximum rates, except for plants from Texas. In the subtropics and tropics where several species co-exist in the same seagrass bed, two types of responses occurred, corresponding to climax versus colonizer species. The difference in the responses appeared in the initial and maximum rates and in sensitivity to high irradiance. Productivity of seagrasses can be estimated, with certain limitations, from light measurements using the equations of Michaelis-Menten and Steele. (Refs. 35).

  12. A DIAGENETIC MODEL FOR SEDIMENT-SEAGRASS INTERACTIONS

    Science.gov (United States)

    The objective of this modeling effort was to better understand the dynamic relationship between seagrass beds and their sedimentary environment using a diagenetic model. The model was developed and optimized for sediments in the Laguna Madre, TX, which is one of the world's larg...

  13. CONTROLS OF SEAGRASS EPIPHYTE ABUNDANCE: DOES LIGHT TRUMP NUTRIENTS?

    Science.gov (United States)

    Epiphytes on seagrass growing in the lower intertidal were examined along an estuarine gradient within Yaquina Bay, Oregon over a period of 4 years. The Yaquina Estuary receives high levels of nutrients from the watershed during the wet season and from the ocean during the dry s...

  14. Carbon Stored on Seagrass Community in Marine Nature Tourism Park of Kotania Bay, Western Seram, Indonesia

    Directory of Open Access Journals (Sweden)

    Mintje Wawo

    2014-04-01

    Full Text Available Currently, the function of seagrass community as carbon storage has been discussed in line with “blue carbon” function of that seagrass has. Seagrass bed are a very valuable coastal ecosystem, however, seagrass bed is threatened if compared to other coastal ecosystems, such as mangroves and coral reefs. The threatened seagrass experienced also contributes to its capacity in absorbing CO2 emission from greenhouse gasses such as CO2 emission Temporal estimation shows that CO2 emission will increase in the coming decade. On the other side, efforts to decrease climate change can be influenced by the existence of seagrass. Informations about existence of seagrass as carbon storage are still very rare or limited. This study was aimed to estimate carbon storage on seagrass community in Marine Nature Tourism Park of Kotania Bay Area, Western Seram, Maluku Province. The quadrat transect method of 0.25 m2 for each plot was used to collect seagrass existence. The content of carbon in the sample of dry biomass of seagrass was analyzed in the laboratory using Walkley & Black method. The results showed that total carbon stored was higher in both Osi and Burung Islands of Kotania Bay than other studied areas (Buntal and Tatumbu Islands, Marsegu Island, Barnusang Peninsula, Loupessy and Tamanjaya Village. The average carbon stored in Kotania Bay waters was 2.385 Mg C ha-1, whereas the total of carbon stored was 2054.4967 Mg C.

  15. Bird colonies cause seagrass enrichment in a subtropical estuary: Observational and experimental evidence

    Science.gov (United States)

    Powell, George V. N.; Fourqurean, James W.; Kenworthy, W. Judson; Zieman, Joseph C.

    1991-06-01

    Colonies/roosts of piscivorous birds in Florida Bay, a subtropical estuary, concentrate nutrients by feeding away from their colonies/roosts and returning with food for young and to defaecate. Seagrass beds surrounding the colony islands were markedly different from those around similar islands that did not contain colonies. Seagrass standing crop was enhanced up to 200 m from bird colony islands compared with islands without colonies. The species of seagrass were also different at colonies, where Halodule wrightii and Ruppia maritima predominated in zones close to the colony islands. Around islands without colonies, only Thalassia testudinum was present. Experimental bird perches placed to stimulate concentrated bird presence produced changes in adjacent seagrass meadows that were similar to differences between islands with colonies and those without. Over 5 years, seagrass standing crop increased around the experimental perches, and species dominance shifted from T. testudinum to H. wrightii. No similar changes occurred at control locations. These experimental results indicate that the bird concentrations are responsible for the observed differences in seagrass communities surrounding islands that contain colonies. These enriched areas are significant to the seagrass ecosystem because many seagrasses in Florida Bay appear to be nutrient-limited. Demersal fish and invertebrate density and species richness have been shown to be a function of the seagrass standing crop and species composition, so the changes in seagrasses stimulated by localized bird concentrations have the capacity to alter the entire community structure.

  16. Zonation and structuring factors of meiofauna communities in a tropical seagrass bed (Gazi Bay, Kenya)

    Science.gov (United States)

    De Troch, Marleen; Gurdebeke, Shirley; Fiers, Frank; Vincx, Magda

    2001-02-01

    This study deals with the relation between tropical meiofauna and environmental variables by comparing the 'benthic' (i.e. in the bare sediment adjacent to seagrass plants) and the 'epiphytic' (i.e. in samples including seagrass plants) meiofauna associated with five seagrass species from the high intertidal to the high subtidal zone in Gazi Bay (Kenya). Ordination and variance analysis revealed three distinct 'benthic' and two 'epiphytic' meiofauna assemblages. These assemblages corresponded entirely with those identified for the seagrass species: a high intertidal pioneer association ( Halophila ovalis/ Halodule wrightii), an intertidal climax assemblage ( Thalassia hemprichii) and a high subtidal pioneer association ( Halophila stipulacea/ Syringodium isoetifolium). These data support the hypothesis that meiofaunal communities correspond to the characteristic zonation of the seagrass vegetation in Gazi Bay. In beds of the pioneer seagrass species, the close relationship between sediment characteristics and both 'benthic' and 'epiphytic' meiofauna communities suggests that these pioneer communities were mainly driven by physical factors. The 'benthic' communities adjacent to the climax seagrass species T. hemprichii were more structured by biogenic factors, e.g. % TOM, chlorophyll a and c, fucoxanthin, habitat complexity and growth form of the seagrass species. For its associated 'epiphytic' meiofauna the latter conclusion was even more striking. These data corroborate the importance of physical factors in disturbed environments (intertidal zone, near pioneer seagrasses) and of biotic factors in more stable conditions (subtidal zone, near climax seagrasses).

  17. Meadow fragmentation and reproductive output of the SE Asian seagrass Enhalus acoroides [rapid communication

    Science.gov (United States)

    Vermaat, Jan E.; Rollon, Rene N.; Lacap, Cristina Day A.; Billot, Claire; Alberto, Filipe; Nacorda, Hildie M. E.; Wiegman, Frank; Terrados, Jorge

    2004-11-01

    Flower and fruit production of the abundant, tall, long-lived, dioecious, surface-pollinating seagrass species Enhalus acoroides (L.) Royle were estimated at seven sites in the reef flats off Bolinao (NW Luzon, The Philippines) featuring different fragmentation of the seagrass meadows. Fragmentation of the seagrass meadow was quantified as cover of E. acoroides and all seagrass species present in 20×20 m plots. E. acoroides and overall seagrass cover were correlated positively. The proportion of female flowers of E. acoroides that developed a fruit increased sharply as overall seagrass cover was around 50%. Apparent sex ratio bore no relationship with overall seagrass cover. This threshold-type of relationship suggests that fragmentation of seagrass meadows can have a major effect on the reproductive output of this species. A possible mechanism underlying these results would be a non-linear increase of the efficiency of trapping the surface-dispersed pollen with increasing seagrass canopy density. This provides the first evidence based on real data that fragmentation can affect the population dynamics of seagrass species.

  18. Seagrass meadows as a globally significant carbonate reservoir

    KAUST Repository

    Mazarrasa, I.

    2015-08-24

    There has been growing interest in quantifying the capacity of seagrass ecosystems to act as carbon sinks as a natural way of offsetting anthropogenic carbon emissions to the atmosphere. However, most of the efforts have focused on the particulate organic carbon (POC) stocks and accumulation rates and ignored the particulate inorganic carbon (PIC) fraction, despite important carbonate pools associated with calcifying organisms inhabiting the meadows, such as epiphytes and benthic invertebrates, and despite the relevance that carbonate precipitation and dissolution processes have in the global carbon cycle. This study offers the first assessment of the global PIC stocks in seagrass sediments using a synthesis of published and unpublished data on sediment carbonate concentration from 403 vegetated and 34 adjacent un-vegetated sites. PIC stocks in the top 1 m of sediment ranged between 3 and 1660 Mg PIC ha−1, with an average of 654 ± 24 Mg PIC ha−1, exceeding those of POC reported in previous studies by about a factor of 5. Sedimentary carbonate stocks varied across seagrass communities, with meadows dominated by Halodule, Thalassia or Cymodocea supporting the highest PIC stocks, and tended to decrease polewards at a rate of −8 ± 2 Mg PIC ha−1 per degree of latitude (general linear model, GLM; p < 0.0003). Using PIC concentrations and estimates of sediment accretion in seagrass meadows, the mean PIC accumulation rate in seagrass sediments is found to be 126.3 ± 31.05 g PIC m−2 yr−1. Based on the global extent of seagrass meadows (177 000 to 600 000 km2), these ecosystems globally store between 11 and 39 Pg of PIC in the top metre of sediment and accumulate between 22 and 75 Tg PIC yr−1, representing a significant contribution to the carbonate dynamics of coastal areas. Despite the fact that these high rates of carbonate accumulation imply CO2

  19. The distribution of seagrasses in Dominica, Lesser Antilles.

    Science.gov (United States)

    Steiner, S C C; Macfarlane, K J; Price, L M; Willette, D A

    2010-10-01

    Seagrass beds are the largest organism-built marine habitat in Dominica, yet have only been surveyed since 2007. Standardized examinations along a depth gradient between 0 and 24 m, focusing on magnoliophyte species composition and benthic cover of shoots at 17 seagrass bed sites, were carried out between September 10 and December 7, 2008. The Cymodoceaceae Syringodium filiforme (Kuetzing 1860) and Halodule wrightii (Ascherson 1868), as well as the Hydrocharitaceae Halophila decipiens (Ostenfeld 1902), H. stipulacea (Fosskal & Ascherson 1867) and Thalassia testudinum (Banks ex König 1805) displayed distinct regional and horizontal distribution patterns. Syringodium filiforme is the island's dominant seagrass along the western and northern coasts, occurring at depths between 2 and 18 m and with a mean benthic cover ranging from 0.9-10% along the West coast. Along the North coast it grew between 0.2 and 1 m depth with a mean maximum benthic cover of 48.9%. Halodule wrightii grew along the North and West coasts, in depths between 1 and 14m in areas of recent and chronic disturbances. Its delicate morphology and sparse benthic cover (< 0.1%) did not constitute seagrass beds. Halophila decipiens grew along the deep, shallow and lateral margins of west coast S. filiforme beds and monospecifically in depths between 3 and 24m. Halophila stipulacea, an invasive species, was widespread along 45km of the West coast and was found in depths between 5 and 24m. Both Halophila species formed extensive beds at depths beyond the survey limit of 24m thus playing a potentially important role in the resettlement of shallow areas after storms. H. decipiens and H. stipulacea are currently the second and third most common seagrasses on the island respectively, despite their absence along the North coast. T. testudinum was confined to North coast's sheltered reef flats at depths Im or less with mean a benthic cover ranging from 2 to 76%. It grew monospecifically in the most turbulent and

  20. Temporal evolution of sand corridors in a Posidonia oceanica seascape: a 15-years study

    Directory of Open Access Journals (Sweden)

    S. GOBERT

    2016-11-01

    Full Text Available The spatial dynamic of Posidonia oceanica meadows is a process extending over centuries. This paper shows evidence of the natural dynamics of P. oceanica “shifting intermattes” or “sand corridors” (hereafter SCs: unvegetated patches within a dense meadow. We studied features and temporal evolution (2001-2015 of 5 SCs in the Calvi Bay (Corsica at 15 m depth and followed the characteristics the P. oceanica meadow lining the edge of patches. All SCs show a similar topography. The eroded side is a vertical edge where roots, rhizomes and sediments are visible, when on the opposite colonized side, the sand is at the same level as the continuous meadow. The vertical edge reaches a maximum height of 160 cm and is eroded by orbital bottom currents with a maximum speed of 12 cm.s-1, the erosion speed ranging from 0.6 to 15 cm.y-1. SCs progress toward the coastline with a mean speed of 10 cm.y-1, the rate of colonization by P. oceanica shoots ranging from 1.5 to 21 cm.y-1. We calculated that the studied SCs would reach the coastline within 500 to 600 years. We finally discuss the implication of such dynamic in the framework of meadows’ colonization assessment and the seascape dynamic.

  1. Short-term effect of beach replenishment on a shallow Posidonia oceanica meadow.

    Science.gov (United States)

    González-Correa, José M; Fernández-Torquemada, Yolanda; Sánchez-Lizaso, José Luis

    2009-09-01

    Putative perturbations on a Posidonia oceanica meadow produced by recent artificial beach nourishment were evaluated in relation to four undisturbed meadows. Temporal variations of putative impacted location vs. control locations of environmental (light availability and sediment features), plant (associated epiphytes, silt-clay fraction attached to epiphytes, herbivore attack, non-structural carbohydrate reserves) and structural parameters (cover and density) of meadows were tested by asymmetrical analysis of variance beyond BACI (Before/After, Control/Impact). Additionally, two asymmetrical analyses of variance were used to test for differences in vegetative growth of horizontal rhizomes (leaf production, horizontal rhizome growth, biomass production and net secondary rhizome recruitment) before and after beach replenishment. Environmental effects induced by dumping works were only detected in connection with a higher silt-clay deposition rate. This increase was consistent with the increase of silt-clay cover attached to epiphytes. As a consequence of silt-clay smothering, a decrease of filter feeding epiphytes, starch reserves, shoot surface and shoot biomass was observed. The sensitivity of plants to sediment inputs, leads us to recommend avoidance of dumping or sediment movement in the vicinity of P. oceanica meadows.

  2. Sp. Radicis-Lycopersici Using Mixture of Vegetable and Posidonia oceanica Compost

    Directory of Open Access Journals (Sweden)

    S. Kouki

    2012-01-01

    Full Text Available A compost of vegetable waste and Posidonia oceanica mixture (70 : 30% vol : vol was tested in vitro and in vivo for its efficacy against Fusarium oxysporum f.sp radicis-lycopersici (Forl, the causal agent of Fusarium wilt of Tomato (Lycopersicon esculentum cv. chourouk.The incorporation of non-sterilized VPC in the culture medium showed potent antifungal activity against Forl and complete inhibition of mycelium growth was observed for all the tested compost rates (0.5, 1, 2, 4, 6, 8, 10, 15 and 20%. However, only the highest rates (15 and 20% of a sterilized suspension of VPC were effective in preventing mycelial growth. Nine indigenous bacterial strains isolated from VPC exhibited antagonism against Forl. Based on 16S rDNA sequence analysis, the isolates were assigned to Bacillus sphaericus (B12 and BS2, Pseudomonas putida PPS7 and Burkholderia gladioli BuC16. Under green house condition, seed inoculation by B12, BS2, PP7 and BuC16 strains protected significantly tomato against Fusarium oxysporum f.sp radicis-lycopersici (Forl attacks.

  3. Testing for thresholds of ecosystem collapse in seagrass meadows.

    Science.gov (United States)

    Connell, Sean D; Fernandes, Milena; Burnell, Owen W; Doubleday, Zoë A; Griffin, Kingsley J; Irving, Andrew D; Leung, Jonathan Y S; Owen, Samuel; Russell, Bayden D; Falkenberg, Laura J

    2017-10-01

    Although the public desire for healthy environments is clear-cut, the science and management of ecosystem health has not been as simple. Ecological systems can be dynamic and can shift abruptly from one ecosystem state to another. Such unpredictable shifts result when ecological thresholds are crossed; that is, small cumulative increases in an environmental stressor drive a much greater change than could be predicted from linear effects, suggesting an unforeseen tipping point is crossed. In coastal waters, broad-scale seagrass loss often occurs as a sudden event associated with human-driven nutrient enrichment (eutrophication). We tested whether the response of seagrass ecosystems to coastal nutrient enrichment is subject to a threshold effect. We exposed seagrass plots to different levels of nutrient enrichment (dissolved inorganic nitrogen) for 10 months and measured net production. Seagrass response exhibited a threshold pattern when nutrient enrichment exceeded moderate levels: there was an abrupt and large shift from positive to negative net leaf production (from approximately 0.04 leaf production to 0.02 leaf loss per day). Epiphyte load also increased as nutrient enrichment increased, which may have driven the shift in leaf production. Inadvertently crossing such thresholds, as can occur through ineffective management of land-derived inputs such as wastewater and stormwater runoff along urbanized coasts, may account for the widely observed sudden loss of seagrass meadows. Identification of tipping points may improve not only adaptive-management monitoring that seeks to avoid threshold effects, but also restoration approaches in systems that have crossed them. © 2017 Society for Conservation Biology.

  4. Seagrass meadows as a globally significant carbonate reservoir

    Directory of Open Access Journals (Sweden)

    I. Mazarrasa

    2015-03-01

    Full Text Available There has been a growing interest in quantifying the capacity of seagrass ecosystems to act as carbon sinks as a natural way of offsetting anthropogenic carbon emissions to the atmosphere. However, most of the efforts have focused on the organic carbon (POC stocks and accumulation rates and ignored the inorganic carbon (PIC fraction, despite important carbonate pools associated with calcifying organisms inhabiting the meadows, such as epiphytes and benthic invertebrates, and despite the relevance that carbonate precipitation and dissolution processes have in the global carbon cycle. This study offers the first assessment of the global PIC stocks in seagrass sediments using a synthesis of published and unpublished data on sediment carbonate concentration from 402 vegetated and 34 adjacent un-vegetated sites. PIC stocks in the top 1 m sediments ranged between 3 and 1660 Mg PIC ha-1, with an average of 654 ± 24 Mg PIC ha-1, exceeding about 5 fold those of POC reported in previous studies. Sedimentary carbonate stocks varied across seagrass communities, with meadows dominated by Halodule, Thalassia or Cymodocea supporting the highest PIC stocks, and tended to decrease polewards at a rate of -8 ± 2 Mg PIC ha-1 degree-1 of latitude (GLM, p -2 y-1. Based on the global extent of seagrass meadows (177 000 to 600 000 km2, these ecosystems globally store between 11 and 39 Pg of PIC in the top meter of sediment and accumulate between 22 and 76 Tg PIC y-1, representing a significant contribution to the carbonate dynamics of coastal areas. Despite that these high rates of carbonate accumulation imply CO2 emissions from precipitation, seagrass meadows are still strong CO2 sinks as demonstrates the comparison of carbon (POC and POC stocks between vegetated and adjacent un-vegetated sediments.

  5. Biomass dynamics of seagrasses and the role of mangrove and seagrass vegetation as different nutrient sources for an intertidal ecosystem

    NARCIS (Netherlands)

    Boer, de W.F.

    2000-01-01

    The input of organic matter and nutrients produced by mangrove and seagrass vegetation in the intertidal bay on Inhaca island, Mozambique, was estimated. Mean mangrove tree height was 2.20 m, diameter at breast height was 6.4 cm and density was 6047 trees per hectare. Above-ground biomass of mangrov

  6. Seagrasses in the Age of Sea Turtle Conservation and Shark Overfishing

    Directory of Open Access Journals (Sweden)

    Michael R Heithaus

    2014-08-01

    Full Text Available Efforts to conserve globally declining herbivorous green sea turtles have resulted in promising growth of some populations. These trends could significantly impact critical ecosystem services provided by seagrass meadows on which turtles feed. Expanding turtle populations could improve seagrass ecosystem health by removing seagrass biomass and preventing of the formation of sediment anoxia. However, overfishing of large sharks, the primary green turtle predators, could facilitate turtle populations growing beyond historical sizes and trigger detrimental ecosystem impacts mirroring those on land when top predators were extirpated. Experimental data from multiple ocean basins suggest that increasing turtle populations can negatively impact seagrasses, including triggering virtual ecosystem collapse. Impacts of large turtle populations on seagrasses are reduced in the presence of intact shark populations. Healthy populations of sharks and turtles, therefore, are likely vital to restoring or maintaining seagrass ecosystem structure, function, and their value in supporting fisheries and as a carbon sink.

  7. Seagrass meadows globally as a coupled social-ecological system: implications for human wellbeing.

    Science.gov (United States)

    Cullen-Unsworth, Leanne C; Nordlund, Lina Mtwana; Paddock, Jessica; Baker, Susan; McKenzie, Len J; Unsworth, Richard K F

    2014-06-30

    Seagrass ecosystems are diminishing worldwide and repeated studies confirm a lack of appreciation for the value of these systems. In order to highlight their value we provide the first discussion of seagrass meadows as a coupled social-ecological system on a global scale. We consider the impact of a declining resource on people, including those for whom seagrass meadows are utilised for income generation and a source of food security through fisheries support. Case studies from across the globe are used to demonstrate the intricate relationship between seagrass meadows and people that highlight the multi-functional role of seagrasses in human wellbeing. While each case underscores unique issues, these examples simultaneously reveal social-ecological coupling that transcends cultural and geographical boundaries. We conclude that understanding seagrass meadows as a coupled social-ecological system is crucial in carving pathways for social and ecological resilience in light of current patterns of local to global environmental change.

  8. Habitat use of a multispecific seagrass meadow by green turtles Chelonia mydas at Mayotte Island

    OpenAIRE

    Ballorain, Katia; Ciccione, Stephane; Bourjea, Jerome; Grizel, Henri; Enstipp, Manfred; Georges, Jean-Yves

    2010-01-01

    We investigated the habitat use in green turtles exploiting a 13-ha multispecific seagrass meadow at Mayotte Island, south-western Indian Ocean. A phytoecological survey shows the occurrence of eight seagrass species, dominated by Halodule uninervis and Syringodium isoetifolium, distributed according to four distinct seagrass communities along the depth gradient. Direct underwater censuses show that green turtles occurred all over the meadow. Yet when community relative surface area was taken...

  9. Dietary preferences of two seagrass inhabiting gastropods: Allochthonous vs autochthonous resources

    Science.gov (United States)

    Doropoulos, C.; Hyndes, G. A.; Lavery, P. S.; Tuya, F.

    2009-06-01

    The movement of allochthonous resources between habitats can provide important trophic linkages in marine landscapes. In coastal south-western Australia, the kelp Ecklonia radiata is removed from reefs and accumulates in large quantities in neighbouring seagrass meadows. This study investigated the feeding preferences and grazing rates of two locally abundant gastropods, Pyrene bidentata and Cantharidus lepidus, which exhibit inverse distribution patterns with proximity to reefs in seagrass meadows, to determine whether allochthonous kelp has the potential to contribute to the seagrass food web. Using laboratory choice and no-choice feeding experiments, we tested whether detached kelp is consumed preferentially, and at greater rates, by these two species than autochthonous resources (i.e. seagrass, epiphytic red macroalgae and seagrass periphyton). Both species displayed a preference for macroalgae and seagrass periphyton over seagrass leaves. In choice experiments, neither species displayed any clear preference between kelp (fresh or aged), red macroalgae or periphyton (consumption rates ranged between 0.39 and 3.64 mg ind -1 day -1), but consumption rates were always higher relative to seagrass. In no-choice experiments, P. bidentata displayed minimal consumption of seagrass, but consumed fresh and aged kelp, red macroalgae and seagrass periphyton at similar rates (2.00-7.22 mg ind -1 day -1). In comparison, C. lepidus consumed periphyton at far greater rates than any other food source (3.61 vs 0.33-1.10 mg ind -1 day -1). The results indicate that both P. bidentata and C. lepidus showed a clear preference for macroalgae and periphyton over seagrass, but no consistent preference towards any autochthonous or allochthonous algal resource. Reef-derived kelp therefore has the potential to contribute to the food web of seagrass meadows, and subsidise secondary production.

  10. Coastal retreat and improved water quality mitigate losses of seagrass from sea level rise.

    Science.gov (United States)

    Saunders, Megan I; Leon, Javier; Phinn, Stuart R; Callaghan, David P; O'Brien, Katherine R; Roelfsema, Chris M; Lovelock, Catherine E; Lyons, Mitchell B; Mumby, Peter J

    2013-08-01

    The distribution and abundance of seagrass ecosystems could change significantly over the coming century due to sea level rise (SLR). Coastal managers require mechanistic understanding of the processes affecting seagrass response to SLR to maximize their conservation and associated provision of ecosystem services. In Moreton Bay, Queensland, Australia, vast seagrass meadows supporting populations of sea turtles and dugongs are juxtaposed with the multiple stressors associated with a large and rapidly expanding human population. Here, the interactive effects of predicted SLR, changes in water clarity, and land use on future distributions of seagrass in Moreton Bay were quantified. A habitat distribution model of present day seagrass in relation to benthic irradiance and wave height was developed which correctly classified habitats in 83% of cases. Spatial predictions of seagrass and presence derived from the model and bathymetric data were used to initiate a SLR inundation model. Bathymetry was iteratively modified based on SLR and sedimentary accretion in seagrass to simulate potential seagrass habitat at 10 year time steps until 2100. The area of seagrass habitat was predicted to decline by 17% by 2100 under a scenario of SLR of 1.1 m. A scenario including the removal of impervious surfaces, such as roads and houses, from newly inundated regions, demonstrated that managed retreat of the shoreline could potentially reduce the overall decline in seagrass habitat to just 5%. The predicted reduction in area of seagrass habitat could be offset by an improvement in water clarity of 30%. Greater improvements in water clarity would be necessary for larger magnitudes of SLR. Management to improve water quality will provide present and future benefits to seagrasses under climate change and should be a priority for managers seeking to compensate for the effects of global change on these valuable habitats.

  11. Familial Mediterranean fever

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000363.htm Familial Mediterranean fever To use the sharing features on this page, please enable JavaScript. Familial Mediterranean fever (FMF) is a rare disorder passed down through ...

  12. Identifying knowledge gaps in seagrass research and management: An Australian perspective.

    Science.gov (United States)

    York, Paul H; Smith, Timothy M; Coles, Rob G; McKenna, Skye A; Connolly, Rod M; Irving, Andrew D; Jackson, Emma L; McMahon, Kathryn; Runcie, John W; Sherman, Craig D H; Sullivan, Brooke K; Trevathan-Tackett, Stacy M; Brodersen, Kasper E; Carter, Alex B; Ewers, Carolyn J; Lavery, Paul S; Roelfsema, Chris M; Sinclair, Elizabeth A; Strydom, Simone; Tanner, Jason E; van Dijk, Kor-Jent; Warry, Fiona Y; Waycott, Michelle; Whitehead, Sam

    2017-06-01

    Seagrass species form important marine and estuarine habitats providing valuable ecosystem services and functions. Coastal zones that are increasingly impacted by anthropogenic development have experienced substantial declines in seagrass abundance around the world. Australia, which has some of the world's largest seagrass meadows and is home to over half of the known species, is not immune to these losses. In 1999 a review of seagrass ecosystems knowledge was conducted in Australia and strategic research priorities were developed to provide research direction for future studies and management. Subsequent rapid evolution of seagrass research and scientific methods has led to more than 70% of peer reviewed seagrass literature being produced since that time. A workshop was held as part of the Australian Marine Sciences Association conference in July 2015 in Geelong, Victoria, to update and redefine strategic priorities in seagrass research. Participants identified 40 research questions from 10 research fields (taxonomy and systematics, physiology, population biology, sediment biogeochemistry and microbiology, ecosystem function, faunal habitats, threats, rehabilitation and restoration, mapping and monitoring, management tools) as priorities for future research on Australian seagrasses. Progress in research will rely on advances in areas such as remote sensing, genomic tools, microsensors, computer modeling, and statistical analyses. A more interdisciplinary approach will be needed to facilitate greater understanding of the complex interactions among seagrasses and their environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Mangrove and seagrass beds provide different biogeochemical services for corals threatened by climate change

    National Research Council Canada - National Science Library

    Emma F Camp; David J Suggett; Gilberte eGendron; Jamaluddin eJompa; Carrie eManfrino; David J Smith

    2016-01-01

    .... Future ocean acidification scenarios have the potential to impact coral growth and associated reef function, although reports suggest such affects could be reduced in adjacent seagrass habitats...

  14. Rhizosphere microbiomes of European seagrasses are selected by the plant, but are not species specific

    Directory of Open Access Journals (Sweden)

    Catarina eCúcio

    2016-03-01

    Full Text Available Seagrasses are marine flowering plants growing in soft-body sediments of intertidal and shallow sub-tidal zones. They play an important role in coastal ecosystems by stabilizing sediments, providing food and shelter for animals, and recycling nutrients. Like other plants, seagrasses live intimately with both beneficial and unfavourable microorganisms. Although much is known about the microbiomes of terrestrial plants, little is known about the microbiomes of seagrasses. Here we present the results of a detailed study on the rhizosphere microbiome of seagrass species across the North-eastern Atlantic Ocean: Zostera marina, Zostera noltii and Cymodocea nodosa. High-resolution amplicon sequencing of 16S rRNA genes showed that the rhizobiomes were significantly different from the bacterial communities of surrounding bulk sediment and seawater. Although we found no significant differences between the rhizobiomes of different seagrass species within the same region, those of seagrasses in different geographical locations differed strongly. These results strongly suggest that the seagrass rhizobiomes are shaped by plant metabolism, but not coevolved with their host. The core rhizobiome of seagrasses includes mostly bacteria involved in the sulfur cycle, thereby highlighting the importance of sulfur-related processes in seagrass ecosystems.

  15. Sulfur cycling and sulfide intrusion in mixed Southeast Asian tropical seagrass meadows

    DEFF Research Database (Denmark)

    Holmer, Marianne; Pedersen, Ole; Ikejima, Kou

    2006-01-01

    Seagrass distribution and sediment biogeochemical conditions were measured around Libong Island in the Andaman Sea, Thailand. Seagrass diversity was moderate for a tropical site (four species found: Cymodocea rotundata, Enhalus acoroides, Halophila ovalis and Thalassia hemprichii), with the dimin...... and sulfide accumulation in concert exert sulfide stress on the seagrasses, as indicated by an accumulation of elemental sulfur in the plants examined, suggesting that tropical seagrasses are prone to sulfide intrusion, similar to findings for temperate seagrasses....... belowground biomass and sulfate reduction rates across the seagrass species examined indicates that stimulation of microbial activity in the rhizosphere sediments is controlled by the biomass of roots and rhizomes, rather than by specific seagrass characteristics (e.g., morphology, plant activity). The low...... iron contents in the seagrass tissues were within the range suggested for nutrient limitation. Sediment sulfur pools, in particular pyrite pools, were high and most of the available iron was bound in sulfides, which may cause iron limitation in seagrass tissues. High sediment sulfide production...

  16. Spatial analysis of carbon isotopes reveals seagrass contribution to fishery food web

    National Research Council Canada - National Science Library

    Connolly, Rod M; Waltham, Nathan J

    2015-01-01

    .... Pooling of modelled contributions from sources with similar isotope values indicated a role for organic matter from seagrass meadows or saltmarshes, but still did not define contributions well...

  17. Thermal evolution and shale gas potential estimation of the Wealden and Posidonia Shale in NW-Germany and the Netherlands : a 3D basin modelling study

    NARCIS (Netherlands)

    Bruns, B.; Littke, R.; Gasparik, M.; van Wees, J.-D.; Nelskamp, S.

    2016-01-01

    Sedimentary basins in NW-Germany and the Netherlands represent potential targets for shale gas exploration in Europe due to the presence of Cretaceous (Wealden) and Jurassic (Posidonia) marlstones/shales as well as various Carboniferous black shales. In order to assess the regional shale gas prospec

  18. On the role of Posidonia oceanica beach wrack for macroinvertebrates of a Tyrrhenian sandy shore

    Science.gov (United States)

    Colombini, Isabella; Mateo, Miguel Ángel; Serrano, Oscar; Fallaci, Mario; Gagnarli, Elena; Serrano, Laura; Chelazzi, Lorenzo

    2009-01-01

    The use of Posidonia oceanica beach wrack by macroinvertebrates of the sandy beach at Burano (Tuscany, Italy) was assessed by following the colonisation dynamics of the wrack and analysing the stable isotopes 'scenario' of the main local carbon and nitrogen sources and consumers. One-hundred experimental cylinders, filled with P. oceanica wrack, were placed on the beach and sampled over a 1-month period. Abundance and species richness of macroinvertebrates in wracks varied through time. Wrack was colonised by crustaceans almost immediately after deployment of the experimental cylinders. The amphipod Talitrus saltator largely dominated the faunal assembly and, together with the isopod Tylos europaeus, occupied the wracks closer to the sealine. These were followed by dipterans, staphylinids, pselaphids and tenebrionids that occurred in drier wracks higher up on the eulittoral. Moisture content of the wrack and sand decreased through space and time. This was the primary factor explaining the spatial and temporal changes observed in macroinvertebrate abundance, with species colonising or abandoning wracks according to thresholds of environmental parameters. Isotopic analysis clearly established the absence of any direct dietary link between P. oceanica wrack and macroinvertebrates. Terrestrial food sources were also discarded. Both our experimental data and a literature search showed that the organic matter from seston as filtered by the sand is the most plausible carbon and nitrogen source for beach food webs. Even if P. oceanica wrack is not a trophic source for macroinvertebrates, it is vitally important as a physical structure that provides detritivorous and predatory species with refuge from environmentally stressful conditions.

  19. Long-term effect of beach replenishment on natural recovery of shallow Posidonia oceanica meadows

    Science.gov (United States)

    González-Correa, José M.; Torquemada, Yolanda Fernández; Sánchez Lizaso, José Luis

    2008-03-01

    The recovery capacity of shallow Posidonia oceanica meadows degraded by beach replenishment eighteen years before was assessed in two impacted meadows and compared with other two undisturbed localities. Inside each locality, we selected randomly three sites separated by 500-1000 m. At site level we study the vitality of P. oceanica meadow assessing the vegetative growth, leaf characteristics, and non-structural carbohydrates of the plants. Additionally, at locality level, silt-clay fraction, organic matter, pH and light intensity incident on the sea bottom were measured to evaluate the environmental conditions. Covering of P. oceanica was significantly lower at the impacted localities while amount of dead "matte" was higher. Leaf production of horizontal rhizomes (14.6 ± 1.11 vs 19.47 ± 1.45 leaves y -1), net total rhizomes recruitment (2.33 ± 0.17 vs 4.3 ± 0.33 branches y -1) and starch concentration (43.625 ± 0.67 vs 54.45 ± 0.74 mg per g of rhizome) at impacted meadows were significantly lower than controls. Leaf features, epiphytes biomass, colonization, elongation and horizontal and vertical rhizome production did not show significant differences. Sediments at impacted localities contained higher silt-clay fraction and higher organic matter load while pH was lower. Light intensity on the sea bottom measured at all localities was over the minimum light requirements estimated for P. oceanica. Our results show that the press impact produced by beach replenishment was enduring in the time slowing natural recovery by 45%. This impact may be related with changes in the sediment features.

  20. MODELING THE DYNAMICS OF THREE FUNCTIONAL GROUPS OF MACROALGAE IN TROPICAL SEAGRASS HABITATS. (R828677C004)

    Science.gov (United States)

    A model of three functional groups of macroalgae, drift algae, rhizophytic calcareous algae, and seagrass epiphytes, was developed to complement an existing seagrass production model for tropical habitats dominated by Thalassia testudinum (Turtle-grass). The current modeling e...

  1. Molecular diversity of diazotrophs in oligotrophic tropical seagrass bed communities.

    Science.gov (United States)

    Bagwell, Christopher E; Rocque, Jeannine R; Smith, Garriett W; Polson, Shawn W; Friez, Michael J; Longshore, John W; Lovell, Charles R

    2002-02-01

    Denaturing gradient gel electrophoresis (DGGE) was employed to resolve PCR-amplified nifH sequences from vegetated and unvegetated sediments from two oligotrophic seagrass bed sites on San Salvador Island, Bahamas, in order to assess diazotroph species composition. All DGGE profiles from these sites showed the same prominent bands. These bands were sequenced, yielding 67 different nifH sequences, which were used in phylogenetic reconstructions. Most sequences were from anaerobes, but some were affiliated with the alpha- and (gamma-+beta-) Proteobacteria. Several NifH sequences were nearly identical to those from Azospirillum brasilense and Vibrio diazotrophicus. These seagrass bed sediments support a diverse diazotroph assemblage that is, at least superficially, similar to that associated with an intertidal grass (Spartina alterniflora).

  2. Photosynthetic carbon reduction by seagrasses exposed to ultraviolet A radiation

    Science.gov (United States)

    1979-01-01

    The seagrasses Halophila engelmannii, Halodule wrightii, and Syringodium filiforme were examined for their intrinsic sensitivity to ultraviolet-A-UV-A and ultraviolet-B-UV-B radiation. The effect of UV-A on photosynthetically active radiation (PAR) was also determined. Ultraviolet-A and ultraviolet-B were studied with emphasis on the greater respective environmental consequence in terms of seagrass distribution and abundance. Results indicate that an intrinsic sensitivity to UV-A alone is apparent only in Halophila, while net photosynthesis in Halodule and Syringodium seems unaffected by the level of UV-A provided. The sensitivity of Halophila to UV-A in the absense of (PAR) indicates that the photosynthetic reaction does not need to be in operation for damage to occur. Other significant results are reported.

  3. Seed germination in a southern Australian temperate seagrass

    Science.gov (United States)

    Jarvis, Jessie C.; Sherman, Craig D.H.; York, Paul H.; Smith, Timothy M.

    2017-01-01

    In a series of experiments, seeds from a temperate seagrass species, Zostera nigricaulis collected in Port Phillip Bay, Victoria, Australia were exposed to a range of salinities (20 PSU pulse/no pulse, 25 PSU, 30 PSU, 35 PSU), temperatures (13 °C, 17 °C, 22 °C), burial depths (0 cm, 1 cm, 2 cm) and site specific sediment characteristics (fine, medium, coarse) to quantify their impacts on germination rate and maximum overall germination. In southern Australia the seagrass Z. nigricaulis is a common subtidal species; however, little is known about the factors that affect seed germination which is a potential limiting factor in meadow resilience to natural and anthropogenic disturbances. Overall seed germination was low (large scale rainfall events. As a result, these populations may be particularly susceptible to disturbance with only a seasonally limited capacity for recovery.

  4. Patterns and mechanisms of dispersal in a keystone seagrass species.

    Science.gov (United States)

    Jahnke, Marlene; Christensen, Asbjørn; Micu, Dragos; Milchakova, Nataliya; Sezgin, Murat; Todorova, Valentina; Strungaru, Stefan; Procaccini, Gabriele

    2016-06-01

    Mechanisms and vectors of long-distance dispersal remain unknown for many coastal benthic species, including plants. Indications for the possibility for long-distance dispersal come from dispersal modelling and from genetic assessments, but have rarely been assessed with both methods. To this end, we assessed dispersal of the seagrass Zostera noltei, an important foundation species of the coastal zone. We investigate whether small scale seed dispersal and long-distance propagule dispersal do play a role for meta-population dynamics, using both genetic assessments based on eight microsatellite markers and physical modelling of ocean currents. Such assessments enhance our understanding of the biology and population dynamics of an important coastal foundation species. They are relevant for large scale conservation strategies as they give insights in the maintenance of genetic diversity and connectivity that may enhance resilience and resistance to stresses associated with seagrass loss.

  5. Seagrass meadows as a globally significant carbonate reservoir

    OpenAIRE

    I. Mazarrasa; N. Marbà; Lovelock, C.E.; SERRANO, O; P. S. Lavery; J. W. Fourqurean; H. Kennedy; Mateo, M.A.; D. Krause-Jensen; A. D. L. Steven; Duarte, C. M.

    2015-01-01

    There has been a growing interest in quantifying the capacity of seagrass ecosystems to act as carbon sinks as a natural way of offsetting anthropogenic carbon emissions to the atmosphere. However, most of the efforts have focused on the organic carbon (POC) stocks and accumulation rates and ignored the inorganic carbon (PIC) fraction, despite important carbonate pools associated with calcifying organisms inhabiting the meadows, such as epiphytes and benthic invertebrates, and...

  6. Seagrass meadows as a globally significant carbonate reservoir

    OpenAIRE

    I. Mazarrasa; N. Marbà; Lovelock, C.E.; SERRANO, O; P. S. Lavery; J. W. Fourqurean; H. Kennedy; Mateo, M.A.; D. Krause-Jensen; A. D. L. Steven; Duarte, C. M.

    2015-01-01

    There has been growing interest in quantifying the capacity of seagrass ecosystems to act as carbon sinks as a natural way of offsetting anthropogenic carbon emissions to the atmosphere. However, most of the efforts have focused on the particulate organic carbon (POC) stocks and accumulation rates and ignored the particulate inorganic carbon (PIC) fraction, despite important carbonate pools associated with calcifying organisms inhabiting the meadows, such as epiphytes and be...

  7. The perilous state of seagrass in the British Isles.

    Science.gov (United States)

    Jones, Benjamin L; Unsworth, Richard K F

    2016-01-01

    Seagrass ecosystems face widespread threat from reduced water quality, coastal development and poor land use. In recent decades, their distribution has declined rapidly, and in the British Isles, this loss is thought to have been extensive. Given increasing knowledge of how these ecosystems support fisheries production, the understanding of their potential rapid loss, and the difficulty in restoring them, it is vital we develop an understanding of the risks they are under, so that management actions can be developed accordingly. Developing an understanding of their environmental status and condition is therefore critical to their long-term management. This study provided, to our knowledge, the first examination of the environmental health of seagrass meadows around the British Isles. This study used a bioindicator approach and involved collecting data on seagrass density and morphology alongside analysis of leaf biochemistry. Our study provides, to the best of our knowledge, the first strong quantitative evidence that seagrass meadows of the British Isles are mostly in poor condition in comparison with global averages, with tissue nitrogen levels 75% higher than global values. Such poor status places their long-term resilience in doubt. Elemental nutrient concentrations and morphological change suggest conditions of excess nitrogen and probable low light, placing many of the meadows sampled in a perilous state, although others, situated away from human populations were perceived to be healthy. Although some sites were of a high environmental health, all sites were considered at risk from anthropogenic impacts, particularly poor water quality and boating-based disturbances. The findings of this study provide a warning of the need to take action, with respect to water quality and disturbance, to prevent the further loss and degradation of these systems across the British Isles.

  8. Seagrass feeding choices and digestive strategies of the herbivorous fish Sarpa salpa.

    Science.gov (United States)

    Goldenberg, S U; Erzini, K

    2014-05-01

    This is the first study investigating the plant-herbivore interaction between Sarpa salpa, which has overgrazed seagrass transplants in Portugal, and the seagrasses Cymodocea nodosa, Zostera marina and Zostera noltii, which have been considered for restoration. When offered the choice between the three seagrasses in outdoor tanks, adult S. salpa clearly preferred Z. noltii. Testing the seagrasses separately, mean ± s.d. feeding rates ranged from 21 ± 11 g seagrass fresh mass kg⁻¹ fish mass day⁻¹ for Z. marina to 32 ± 9 g seagrass fresh mass kg⁻¹ fish mass day⁻¹ for C. nodosa and 40 ± 11 g seagrass fresh mass kg⁻¹ fish mass day⁻¹ for Z. noltii (temperature = 16° C). Food-processing rate in S. salpa did not differ between seagrasses, and there was no evidence of a regulation of processing rate according to food intake. Seagrasses differed substantially in nitrogen content and C:N, with C. nodosa containing the highest nitrogen content and lowest C:N (2·5 ± 0·1% and 14·0 ± 1·0), followed by Z. noltii (2·1 ± 0·1% and 17·0 ± 1·0) and Z. marina (1·4 ± 0·1% and 26·0 ± 2·0). Food-processing rate in S. salpa and the nutritional value of the seagrasses were not correlated with the observed feeding preference and rate. The study suggests that C. nodosa and Z. marina are less at risk of overgrazing by S. salpa and might thus be preferable to Z. noltii for seagrass restoration in areas with noticeable abundances of this fish.

  9. Unravelling complexity in seagrass systems for management: Australia as a microcosm.

    Science.gov (United States)

    Kilminster, Kieryn; McMahon, Kathryn; Waycott, Michelle; Kendrick, Gary A; Scanes, Peter; McKenzie, Len; O'Brien, Katherine R; Lyons, Mitchell; Ferguson, Angus; Maxwell, Paul; Glasby, Tim; Udy, James

    2015-11-15

    Environmental decision-making applies transdisciplinary knowledge to deliver optimal outcomes. Here we synthesise various aspects of seagrass ecology to aid environmental decision-making, management and policy. Managers often mediate conflicting values and opinions held by different stakeholders. Critical to this role is understanding the drivers for change, effects of management actions and societal benefits. We use the diversity of seagrass habitats in Australia to demonstrate that knowledge from numerous fields is required to understand seagrass condition and resilience. Managers are often time poor and need access to synthesised assessments, commonly referred to as narratives. However, there is no single narrative for management of seagrass habitats in Australia, due to the diversity of seagrass meadows and dominant pressures. To assist the manager, we developed a classification structure based on attributes of seagrass life history, habitat and meadow form. Seagrass communities are formed from species whose life history strategies can be described as colonising, opportunistic or persistent. They occupy habitats defined by the range and variability of their abiotic environment. This results in seagrass meadows that are either transitory or enduring. Transitory meadows may come and go and able to re-establish from complete loss through sexual reproduction. Enduring meadows may fluctuate in biomass but maintain a presence by resisting pressures across multiple scales. This contrast reflects the interaction between the spatial and temporal aspects of species life history and habitat variability. Most management and monitoring strategies in place today favour enduring seagrasses. We adopt a functional classification of seagrass habitats based on modes of resilience to inform management for all seagrass communities. These concepts have world-wide relevance as the Australian case-studies have many analogues throughout the world. Additionally, the approach used to

  10. Genetic diversity of seagrass seeds influences seedling morphology and biomass.

    Science.gov (United States)

    Randall Hughes, A; Hanley, Torrance C; Schenck, Forest R; Hays, Cynthia G

    2016-12-01

    Genetic diversity can influence ecological processes throughout ontogeny, yet whether diversity at early life history stages is important in long-lived taxa with overlapping generations is unclear. Seagrass systems provide some of the best evidence for the ecological effects of genetic diversity among adult shoots, but we do not know if the genetic diversity of seeds and seedlings also influences seagrass ecology. We tested the effects of seagrass (Zostera marina) seed diversity and relatedness on germination success, seedling morphology, and seedling production by comparing experimental assemblages of seeds collected from single reproductive shoots ("monocultures") to assemblages of seeds collected from multiple reproductive shoots ("polycultures"). There was no difference in seedling emergence, yet seedlings from polycultures had larger shoots above and below ground than seedlings from monocultures at the end of the 1-yr experiment. Genetic relatedness of the seedlings predicted some aspects of shoot morphology, with more leaves and longer roots and shoots at intermediate levels of relatedness, regardless of seed diversity. Our results suggest that studies of only adult stages may underestimate the importance of genetic diversity if the benefits at early life history stages continue to accrue throughout the life cycle. © 2016 by the Ecological Society of America.

  11. Inhibition of seagrass photosynthesis by ultraviolet-B radiation

    Energy Technology Data Exchange (ETDEWEB)

    Trocine, R.P.; Rice, J.D.; Wells, G.N.

    1981-07-01

    Effects of ultraviolet-B radiation on the photosynthesis of seagrasses (Halophila engelmanni Aschers, Halodule wrightii Aschers, and Syringodium filiforme (Kuetz) were examined. The intrinsic tolerance of each seagrass to ultraviolet-B, the presence and effectiveness of photorepair mechanisms to ultraviolet-B-induced photosynthetic inhibition, and the role of epiphytic growth as a shield from ultraviolet-B were investigated. Halodule was found to possess the greatest photosynthetic tolerance for ultraviolet-B. Photosynthesis in Syringodium was slightly more sensitive to ultraviolet-B while Halophila showed relatively little photosynthetic tolerance. Evidence for a photorepair mechanism was found only in Halodule. Syringodium appeared to rely primarily on a thick epidermal cell layer to reduce photosynthetic damage. Halophila seemed to have no morphological or photorepair capabilities to deal with ultraviolet-B. This species appeared to rely on epiphytic and detrital shielding and the shade provided by other seagrasses to reduce ultraviolet-B irradiation to tolerable levels. The presence of epiphytes on leaf surfaces was found to reduce the extent of photosynthetic inhibition from ultraviolet-B exposure in all species. Halophila appears to obtain an increased photosynthetic tolerance to ultraviolet-B as an indirect benefit of chloroplast clumping to avoid photo-oxidation by intense levels of photosynthetically active radiation.

  12. Middle Eocene seagrass facies from Apennine carbonate platforms (Italy)

    Science.gov (United States)

    Tomassetti, Laura; Benedetti, Andrea; Brandano, Marco

    2016-04-01

    Two stratigraphic sections located in the Latium-Abruzzi (Monte Porchio, Central Apennines, Central Italy) and in the Apulian carbonate platform (S. Cesarea-Torre Tiggiano, Salento, Southern Italy) were measured and sampled to document the sedimentological characteristic and the faunistic assemblages of Middle Eocene seagrass deposits. The faunistic assemblages are dominated by porcellaneous foraminifera Orbitolites, Alveolina, Idalina, Spiroloculina, Quinqueloculina, Triloculina and abundant hooked-shaped gypsinids, associated with hooked red algae and green algae Halimeda. Fabiania, rotaliids and textulariids as well as nummulitids are subordinated. The samples were assigned to Lutetian (SBZ13-16) according to the occurrence of Nummulites cf. lehneri, Alveolina ex. gr. elliptica, Idalina berthelini, Orbitolites complanatus, Slovenites decastroi and Medocia blayensis. At Santa Cesarea reticulate nummulites occur in association with Alveolina spp. and Halkyardia minima marking the lower Bartonian (SBZ17). Three main facies associations have been recognised: I) larger porcellaneous foraminiferal grainstones with orbitolitids and alveolinids deposited into high-energy shallow-water settings influenced by wave processes that reworked the sediments associated with a seagrass; II) grainstone to packstone with small porcellaneous foraminifera and abundant permanently-attached gypsinids deposited in a more protected (e.g., small embayment) in situ vegetated environment; III) bioclastic packstone with parautochthonous material reworked from the seagrass by rip currents and accumulated into rip channels in a slightly deeper environment. The biotic assemblages suggest that the depositional environment is consistent with tropical to subtropical vegetated environments within oligotrophic conditions.

  13. Differences in nutrient concentrations and resources between seagrass communities on carbonate and terrigenous sediments in South Sulawesi, Indonesia

    NARCIS (Netherlands)

    Erftemeijer, P.L.A.

    1994-01-01

    Water column, sediment and plant parameters were studied in six tropical seagrass beds in South Sulawesi, Indonesia, to evaluate the relation between seagrass bed nutrient concentrations and sediment type. Coastal seagrass beds on terrigenous sediments had considerably higher biomass of phytoplankto

  14. Tsunami Impacts on Biodiversity of Seagrass Communities in the Andaman Sea, Thailand: (1) Seagrass Abundance and Diversity

    OpenAIRE

    Nakaoka, Masahiro; Tanaka, Yoshiyuki; Mukai, Hiroshi; Suzuki, Takao; Aryuthaka, Chittima

    2007-01-01

    Evaluation of the impact of a catastrophic disturbance on biodiversity is often difficult due to a lack of sufficient quantitative data on biological communities prior to the disturbance. Since 2001, we have been monitoring the abundance and biomass of seagrass and its associated animal community along the Andaman Sea coast of Thailand, an area that was hit by a tsunami originating in the Indian Ocean on Dec. 26, 2004. To quantitatively evaluate the effects of the disturbance on the biodivers...

  15. Caribbean mangroves and seagrass beds as diurnal feeding habitats for juvenile French grunts, Haemulon flavolineatum.

    NARCIS (Netherlands)

    Verwey, M.C.; Nagelkerken, I.; Wartenbergh, S.L.J.; Pen, I.R.; Velde, G. van der

    2006-01-01

    Abstract Caribbean seagrass beds are important feeding habitats for so-called nocturnally active zoobenthivorous fish, but the extent to which these fishes use mangroves and seagrass beds as feeding habitats during daytime remains unclear. We hypothesised three feeding strategies: (1) fishes feed

  16. EFFECTS OF GREEN MACROALGAE ON CLASSIFICATION OF SEAGRASS IN SIDE SCAN SONAR IMAGERY

    Science.gov (United States)

    High resolution maps of seagrass beds are useful for monitoring estuarine condition, managing fish habitats, and modeling estuarine processes. Side scan sonar (SSS) is one method for producing spatially accurate seagrass maps, although it has not been used widely. Our team rece...

  17. The role of seagrasses in coastal protection in a changing climate

    NARCIS (Netherlands)

    Ondiviela, B.; Losada, I.J.; Lara, J.L.; Maza, M.; Galván, C.; Bouma, T.J.; van Belzen, J.

    2014-01-01

    The contribution of seagrasses to coastal protection is examined through the review of the most relevant existing knowledge. Seagrasses are the largest submerged aquatic vegetation ecosystem protected in Europe and it is worth examining their contribution to coastal protection. The review performed

  18. Dynamics of organic and inorganic carbon across contiguous mangrove and seagrass systems (Gazi Bay, Kenya)

    NARCIS (Netherlands)

    Bouillon, S.; Dehairs, F.; Velimirov, B.; Abril, G.; Borges, A.V.

    2007-01-01

    We report on the water column biogeochemistry in adjacent mangrove and seagrass systems in Gazi Bay (Kenya), with a focus on assessing the sources and cycling of organic and inorganic carbon. Mangrove and seagrass-derived material was found to be the dominant organic carbon sources in the water colu

  19. The use of Sentinel-2 imagery for seagrass mapping: Kalloni Gulf (Lesvos Island, Greece) case study

    Science.gov (United States)

    Topouzelis, Konstantinos; Charalampis Spondylidis, Spyridon; Papakonstantinou, Apostolos; Soulakellis, Nikolaos

    2016-08-01

    Seagrass meadows play a significant role in ecosystems by stabilizing sediment and improving water clarity, which enhances seagrass growing conditions. It is high on the priority of EU legislation to map and protect them. The traditional use of medium spatial resolution satellite imagery e.g. Landsat-8 (30m) is very useful for mapping seagrass meadows on a regional scale. However, the availability of Sentinel-2 data, the recent ESA's satellite with its payload Multi-Spectral Instrument (MSI) is expected to improve the mapping accuracy. MSI designed to improve coastline studies due to its enhanced spatial and spectral capabilities e.g. optical bands with 10m spatial resolution. The present work examines the quality of Sentinel-2 images for seagrass mapping, the ability of each band in detection and discrimination of different habitats and estimates the accuracy of seagrass mapping. After pre-processing steps, e.g. radiometric calibration and atmospheric correction, image classified into four classes. Classification classes included sub-bottom composition e.g. seagrass, soft bottom, and hard bottom. Concrete vectors describing the areas covered by seagrass extracted from the high-resolution satellite image and used as in situ measurements. The developed methodology applied in the Gulf of Kalloni, (Lesvos Island - Greece). Results showed that Sentinel-2 images can be robustly used for seagrass mapping due to their spatial resolution, band availability and radiometric accuracy.

  20. Learning about Coastal Trends: What Is the Story with Seagrass... and How Does It Affect Me?

    Science.gov (United States)

    Ksiazek, Kelly; McGlathery, Karen; Reynolds, Laura; Schwarzschild, Arthur; Wilkerson, Carissa; Carruthers, Tim; Gurbisz, Cassie; Woerner, Joanna L.; Murray, Laura

    2009-01-01

    Flowering plants that live underwater in marine and estuarine habitats (seagrasses) are important because they support human food sources, such as crabs and fish, as well as endangered animals, such as turtles and manatees. Seagrasses are now known to be declining globally, largely as a result of increasing pressure from human populations living…

  1. Restoration scaling of seagrass habitats in the oceanic islands of Lakshadweep, India using geospatial technology

    Digital Repository Service at National Institute of Oceanography (India)

    Nobi, E.P.; Dilipan, E.; Thangaradjou, T.; DineshKumar, P.K.

    of 2000 and 2008. In situ observations were made by skin diving with GPS to verify the map produced for the seagrass denuded area and if seagrasses are found regenerated in those areas, necessary corrections were carried out in the map; incorporating...

  2. Phylogeny and temporal divergence of the seagrass family Zosteraceae using one nuclear and three chloroplast loci

    NARCIS (Netherlands)

    Coyer, J. A.; Hoarau, G.; Kuo, J.; Tronholm, A.; Veldsink, J.; Olsen, J. L.

    2013-01-01

    Seagrasses are among the most productive habitats in the marine realm, performing several crucial physical and biological ecosystem services. One group of seagrasses is the family Zosteraceae, which includes three to four genera and >20 species inhabiting temperate waters of both the northern and so

  3. Are Caribbean mangroves important feeding grounds for juvenile reef fish from adjacent seagrass beds?

    NARCIS (Netherlands)

    Nagelkerken, I.A.; Velde, G. van der

    2004-01-01

    Little evidence is available on how juvenile fishes utilise seagrass beds and adjacent mangroves as feeding habitats. In this study we tested the degree to which Caribbean mangroves are utilised as feeding grounds by the fish community from adjacent seagrass beds. Stable carbon and nitrogen isotope

  4. Expansion and fragment settlement of the non-native seagrass Halophila stipulacea in a Caribbean bay

    NARCIS (Netherlands)

    Smulders, Fee O.H.; Vonk, J.A.; Engel, M.S.; Christianen, Marjolijn J.A.

    2017-01-01

    The non-native seagrass species Halophila stipulacea has spread throughout the Eastern Caribbean since 2002, and could potentially impact the functioning of local seagrass ecosystems. Important characteristics for invasiveness, such as dispersal, recruitment and expansion of H. stipulacea at a lo

  5. Short-Term Sediment Burial Effects on the Seagrass Phyllospadix scouleri

    Science.gov (United States)

    2008-09-01

    they inhabit exposed, rocky shore intertidal and subtidal environments (den Hartog 1970, Phillips and Meñez 1988). Like other seagrasses...coast of Baja California Sur, Mexico. New Zealand Journal of Marine and Freshwater Research. 39: 425-435. den Hartog , C. 1970. The seagrasses of the

  6. Satellite-based monitoring of tropical seagrass vegetation: current techniques and future developments

    NARCIS (Netherlands)

    Ferwerda, J.G.; Leeuw, de J.; Atzberger, C.; Vekerdy, Z.

    2007-01-01

    Decline of seagrasses has been documented in many parts of the world. Reduction in water clarity, through increased turbidity and increased nutrient concentrations, is considered to be the primary cause of seagrass loss. Recent studies have indicated the need for new methods that will enable early

  7. Mangroves and seagrass beds as diurnal feeding habitats for juvenile Haemulon flavolineatum

    NARCIS (Netherlands)

    Verweij, M.C.; Nagelkerken, I.; Wartenbergh, S.L.J.; Pen, I.R.; Velde, G. van der

    2007-01-01

    Caribbean seagrass beds supposedly are important feeding habitats for so-called nocturnally active zoobenthivorous fish, but the extent to which these fishes use mangroves and seagrass beds as feeding habitats during daytime remains unclear. Therefore, we studied daytime behavior of large juvenile (

  8. Habitat restoration: Early signs and extent of faunal recovery relative to seagrass recovery

    Science.gov (United States)

    McSkimming, Chloe; Connell, Sean D.; Russell, Bayden D.; Tanner, Jason E.

    2016-03-01

    The overall intent of restoration is often not only to restore the habitat per se, but to restore the ecosystem services it supplies, and particularly to encourage the return of fauna. Seagrass meadows act as habitat for some of the most diverse and abundant animal life, and as the global loss of seagrass continues, managers have sought to restore lost meadows. We tested how quickly the epifaunal richness, abundances and community composition of experimental restoration plots recovered to that in an adjacent natural seagrass meadow relative to the recovery of seagrass per se. Seagrass structure in the restoration plots took three years to become similar to a nearby natural meadow. The recovery of epifaunal richness and total abundance, however, occurred within one year. These results suggest that although recovering habitats may not be structurally similar to undisturbed habitats, they can support similar richness and abundances of epifauna, and thus have greater economic and social value than otherwise might have been expected. Nevertheless, whilst epifaunal richness and total abundance recovered prior to the recovery of seagrass structure, full recovery of seagrass was required before the composition and relative abundances of the epifaunal community matched that of the natural seagrass meadow.

  9. Cover versus recovery: Contrasting responses of two indicators in seagrass beds

    NARCIS (Netherlands)

    Soissons, L.M.; Han, Q.; Li, B.; van Katwijk, M.M.; Ysebaert, T.; Herman, P.M.J.; Bouma, T.J.

    2014-01-01

    Despite being a highly valuable key-stone ecosystem, seagrass meadows are threatened and declining worldwide, creating urgent need for indicators of their health status. We compared two indicators for seagrass health: standing leaf area index versus relative recovery from local disturbance. Disturba

  10. Are Caribbean mangroves important feeding grounds for juvenile reef fish from adjacent seagrass beds?

    NARCIS (Netherlands)

    Nagelkerken, I.A.; Velde, G. van der

    2004-01-01

    Little evidence is available on how juvenile fishes utilise seagrass beds and adjacent mangroves as feeding habitats. In this study we tested the degree to which Caribbean mangroves are utilised as feeding grounds by the fish community from adjacent seagrass beds. Stable carbon and nitrogen isotope

  11. SEAGRASS STRESS RESPONSE MODEL: THE IMPORTANCE OF LIGHT, TEMPERATURE, SEDIMENTATION AND GEOCHEMISTRY

    Science.gov (United States)

    Our objective is to define interactions between seagrass and water-column and sediment stressors. The model was developed and optimized for sediments in Thalassia testudinum seagrass beds of Lower Laguna Madre, Texas, USA and is composed of a plant sub-model and a sediment diagen...

  12. Phylogeny and temporal divergence of the seagrass family Zosteraceae using one nuclear and three chloroplast loci

    NARCIS (Netherlands)

    Coyer, J. A.; Hoarau, G.; Kuo, J.; Tronholm, A.; Veldsink, J.; Olsen, J. L.

    2013-01-01

    Seagrasses are among the most productive habitats in the marine realm, performing several crucial physical and biological ecosystem services. One group of seagrasses is the family Zosteraceae, which includes three to four genera and >20 species inhabiting temperate waters of both the northern and

  13. Let it flow: how does an underlying current affect wave propagation over a natural seagrass meadow?

    NARCIS (Netherlands)

    Paul, M.; Gillis, L.G.

    2015-01-01

    Temperate seagrass beds can be found within intertidal and tidal areas of variable hydrodynamic forcing. To investigate the interaction between hydrodynamics and seagrass plants, Zostera noltii meadows were exposed to a range of combinations of waves and flow in a flume. Velocity profiles were obtai

  14. Ecology of seagrass bed of Halophila beccarii (Aschers) in Mandovi estuary, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Jagtap, T.G.; Untawale, A.G.

    of seagrass bed. Maximum average biomass of 26.44 g/m2 was recorded in October followed by a flowering period of the seagrass. Protein content was maximum (393.12 mg/g) in August while carbohydrate was maximum (476.18 mg/g) in May and August. Maximum organic...

  15. Leaf nutrient resorption, leaf lifespan and the retention of nutrients in seagrass systems

    NARCIS (Netherlands)

    Hemminga, M.A.; Marbà, N.; Stapel, J.

    1999-01-01

    Efficient nutrient resorption from senescing leaves, and extended leaf life spans are important strategies in order to conserve nutrients for plants in general. Despite the fact that seagrasses often grow in oligotrophic waters, these conservation strategies are not strongly developed in seagrasses.

  16. Satellite-based monitoring of tropical seagrass vegetation: current techniques and future developments

    NARCIS (Netherlands)

    Ferwerda, J.G.; Leeuw, de J.; Atzberger, C.; Vekerdy, Z.

    2007-01-01

    Decline of seagrasses has been documented in many parts of the world. Reduction in water clarity, through increased turbidity and increased nutrient concentrations, is considered to be the primary cause of seagrass loss. Recent studies have indicated the need for new methods that will enable early d

  17. DISTRIBUTION AND QUALITY OF SEAGRASS MEADOWS IN THE PENSACOLA BAY SYSTEM

    Science.gov (United States)

    Abstract for oral presentation: Seagrass meadows have 22 ecological benefits and have an estimated value of $20,500 per acre in Florida. Seagrass meadows support a variety of marine life that includes macroalgae (148 species), epiphytes (1 13 species), macroinvertebrates (230 spe...

  18. SEAGRASS EPIPHYTES AS A NUTRIENT STRESSOR INDICATOR: APPROACHES TOWARDS DEVELOPMENT OF THRESHOLD VALUES.

    Science.gov (United States)

    Epiphytes on seagrasses have been studied for more than 50 years, and proposed as an indicator of anthropogenic nutrient enrichment for over 30 years. Epiphytes have been correlated with seagrass declines, causally related to nutrient additions in both field and mesocosm experim...

  19. A Monte Carlo study of the seagrass-induced depth bias in bathymetric lidar.

    Science.gov (United States)

    Wang, Chi-Kuei; Philpot, William; Kim, Minsu; Lei, Hou-Meng

    2011-04-11

    A bathymetric lidar survey is the most cost efficient method of producing bathymetric maps in near shore areas where the ocean bottom is both highly variable and of greatest importance for shipping and recreation. So far, not much attention has been paid to the influence of bottom materials on the lidar signals. This study addresses this issue using a Monte Carlo modeling technique. The Monte Carlo simulation includes a plane parallel water body and a flat bottom with or without seagrass. The seagrass canopy structure is adopted from Zimmerman (2003). Both the surface of the seagrass leaves and the bottom are assumed to be Lambertian. Convolution with the lidar pulse function followed by the median operator is used to reduce the variance of the resultant lidar waveform. Two seagrass orientation arrangements are modeled: seagrass in still water with random leaf orientation and seagrass with a uniform orientation as would be expected when under the influence of a water current. For each case, two maximum canopy heights, 0.5 m and 1 m, three shoot densities, 100, 500, and 1000, and three bending angles, 5, 25, and 45 degrees, are considered. The seagrass is found to induce a depth bias that is proportional to an effective leaf area index (eLAI) and the contrast in reflectance between the seagrass and the bottom material.

  20. Surviving in changing seascapes : Sediment dynamics as bottleneck for long-term seagrass presence

    NARCIS (Netherlands)

    Suykerbuyk, Wouter; Bouma, Tjeerd J.; Govers, Laura L.; Giesen, Kris; de Jong, Dick J.; Herman, Peter; Hendriks, Jan; van Katwijk, Marieke M.

    2016-01-01

    Changes in the seascape often result in altered hydrodynamics that lead to coinciding changes in sediment dynamics. Little is known on how altered sediment dynamics affect long-term seagrass persistence. We studied the thresholds of sediment dynamics in relation to seagrass presence by comparing sed

  1. Caribbean mangroves and seagrass beds as daytime feeding habitats for juvenile French grunts, Haemulon flavolineatum

    NARCIS (Netherlands)

    Verweij, M.C.; Nagelkerken, I.; Wartenbergh, S.L.J.; Pen, I.R.; Van der Velde, G.

    2006-01-01

    Caribbean seagrass beds are important feeding habitats for so-called nocturnally active zoobenthivorous fish, but the extent to which these fishes use mangroves and seagrass beds as feeding habitats during daytime remains unclear. We hypothesised three feeding strategies: (1) fishes feed opportunist

  2. Losses and recovery of organic carbon from a seagrass ecosystem following disturbance.

    Science.gov (United States)

    Macreadie, Peter I; Trevathan-Tackett, Stacey M; Skilbeck, Charles G; Sanderman, Jonathan; Curlevski, Nathalie; Jacobsen, Geraldine; Seymour, Justin R

    2015-10-22

    Seagrasses are among the Earth's most efficient and long-term carbon sinks, but coastal development threatens this capacity. We report new evidence that disturbance to seagrass ecosystems causes release of ancient carbon. In a seagrass ecosystem that had been disturbed 50 years ago, we found that soil carbon stocks declined by 72%, which, according to radiocarbon dating, had taken hundreds to thousands of years to accumulate. Disturbed soils harboured different benthic bacterial communities (according to 16S rRNA sequence analysis), with higher proportions of aerobic heterotrophs compared with undisturbed. Fingerprinting of the carbon (via stable isotopes) suggested that the contribution of autochthonous carbon (carbon produced through plant primary production) to the soil carbon pool was less in disturbed areas compared with seagrass and recovered areas. Seagrass areas that had recovered from disturbance had slightly lower (35%) carbon levels than undisturbed, but more than twice as much as the disturbed areas, which is encouraging for restoration efforts. Slow rates of seagrass recovery imply the need to transplant seagrass, rather than waiting for recovery via natural processes. This study empirically demonstrates that disturbance to seagrass ecosystems can cause release of ancient carbon, with potentially major global warming consequences.

  3. Caribbean mangroves and seagrass beds as diurnal feeding habitats for juvenile French grunts, Haemulon flavolineatum.

    NARCIS (Netherlands)

    Verwey, M.C.; Nagelkerken, I.; Wartenbergh, S.L.J.; Pen, I.R.; Velde, G. van der

    2006-01-01

    Abstract Caribbean seagrass beds are important feeding habitats for so-called nocturnally active zoobenthivorous fish, but the extent to which these fishes use mangroves and seagrass beds as feeding habitats during daytime remains unclear. We hypothesised three feeding strategies: (1) fishes feed o

  4. Surviving in Changing Seascapes: Sediment Dynamics as Bottleneck for Long-Term Seagrass Presence

    NARCIS (Netherlands)

    Suykerbuyk, W.; Bouma, T.J.; Govers, L.L.; Giesen, K.; de Jong, D.J.; Herman, P.M.J.; Hendriks, J.; van Katwijk, M.M.

    2016-01-01

    Changes in the seascape often result in altered hydrodynamics that lead to coinciding changes in sediment dynamics. Little is known on how altered sediment dynamics affect long-term seagrass persistence. We studied the thresholds of sediment dynamics in relation to seagrass presence by comparing sed

  5. Predicting habitat distribution to conserve seagrass threatened by sea level rise

    Science.gov (United States)

    Saunders, M. I.; Baldock, T.; Brown, C. J.; Callaghan, D. P.; Golshani, A.; Hamylton, S.; Hoegh-guldberg, O.; Leon, J. X.; Lovelock, C. E.; Lyons, M. B.; O'Brien, K.; Mumby, P.; Phinn, S. R.; Roelfsema, C. M.

    2013-12-01

    Sea level rise (SLR) over the 21st century will cause significant redistribution of valuable coastal habitats. Seagrasses form extensive and highly productive meadows in shallow coastal seas support high biodiversity, including economically valuable and threatened species. Predictive habitat models can inform local management actions that will be required to conserve seagrass faced with multiple stressors. We developed novel modelling approaches, based on extensive field data sets, to examine the effects of sea level rise and other stressors on two representative seagrass habitats in Australia. First, we modelled interactive effects of SLR, water clarity and adjacent land use on estuarine seagrass meadows in Moreton Bay, Southeast Queensland. The extent of suitable seagrass habitat was predicted to decline by 17% by 2100 due to SLR alone, but losses were predicted to be significantly reduced through improvements in water quality (Fig 1a) and by allowing space for seagrass migration with inundation. The rate of sedimentation in seagrass strongly affected the area of suitable habitat for seagrass in sea level rise scenarios (Fig 1b). Further research to understand spatial, temporal and environmental variability of sediment accretion in seagrass is required. Second, we modelled changes in wave energy distribution due to predicted SLR in a linked coral reef and seagrass ecosystem at Lizard Island, Great Barrier Reef. Scenarios where the water depth over the coral reef deepened due to SLR and minimal reef accretion, resulted in larger waves propagating shoreward, changing the existing hydrodynamic conditions sufficiently to reduce area of suitable habitat for seagrass. In a scenario where accretion of the coral reef was severely compromised (e.g. warming, acidification, overfishing), the probability of the presence of seagrass declined significantly. Management to maintain coral health will therefore also benefit seagrasses subject to SLR in reef environments. Further

  6. Seagrass ecosystems reduce exposure to bacterial pathogens of humans, fishes, and invertebrates.

    Science.gov (United States)

    Lamb, Joleah B; van de Water, Jeroen A J M; Bourne, David G; Altier, Craig; Hein, Margaux Y; Fiorenza, Evan A; Abu, Nur; Jompa, Jamaluddin; Harvell, C Drew

    2017-02-17

    Plants are important in urban environments for removing pathogens and improving water quality. Seagrass meadows are the most widespread coastal ecosystem on the planet. Although these plants are known to be associated with natural biocide production, they have not been evaluated for their ability to remove microbiological contamination. Using amplicon sequencing of the 16S ribosomal RNA gene, we found that when seagrass meadows are present, there was a 50% reduction in the relative abundance of potential bacterial pathogens capable of causing disease in humans and marine organisms. Moreover, field surveys of more than 8000 reef-building corals located adjacent to seagrass meadows showed twofold reductions in disease levels compared to corals at paired sites without adjacent seagrass meadows. These results highlight the importance of seagrass ecosystems to the health of humans and other organisms.

  7. Photosynthethic carbon reduction by seagrasses exposed to ultraviolet b radiation. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    1979-03-15

    The species of seagrasses were selected on the basis of their dominance in the marine system, contribution to total productivity, and importance to the life histories of organisms in the Indian River lagoon system along the central Florida east coast. The three seagrasses were Halophilia engelmannii, Halodule wrightii, and Syringodium filiforme. These seagrasses form an excellent experimental system as their areas of dominance fall more or less along a natural gradient of UV-B and photosynthetically active radiation (PAR) penetration. The sensitivity of photosynthesis in the seagrasses was determined and their photosynthetic response to levels of UV-B simulating atmospheric ozone depletion was monitored. Further experiments explore the possible attenuation or repair of UV-B induced photosynthetic inhibition by PAR, the role of epiphytic growth upon seagrasses as a protective UV-B shield, and the inhibition of photosynthesis in response to UV-A is studied.

  8. A Meta-Analysis of Seaweed Impacts on Seagrasses: Generalities and Knowledge Gaps

    DEFF Research Database (Denmark)

    Thomsen, M. S.; Wernberg, T.; Engelen, A. H.

    2012-01-01

    are replaced with unstable sediments, turbid waters, hypoxia, and poor habitat conditions for fishes and invertebrates. Understanding the situations under which seaweeds impact seagrasses on local patch scales can help proactive management and prevent losses at greater scales. Here, we provide a quantitative......Seagrasses are important habitat-formers and ecosystem engineers that are under threat from bloom-forming seaweeds. These seaweeds have been suggested to outcompete the seagrasses, particularly when facilitated by eutrophication, causing regime shifts where green meadows and clear waters...... identified major knowledge gaps that need to be addressed before general predictive models on seaweed-seagrass interactions can be build, in order to effectively protect seagrass habitats from detrimental competition from seaweeds....

  9. Direct contribution of the seagrass Thalassia testudinum to lime mud production.

    Science.gov (United States)

    Enríquez, Susana; Schubert, Nadine

    2014-05-22

    Seagrass beds contribute to oceanic carbonate lime mud production by providing a habitat for a wide variety of calcifying organisms and acting as efficient sediment traps. Here we provide evidence for the direct implication of Thalassia testudinum in the precipitation of aragonite needles. The crystals are located internally in the cell walls, and as external deposits on the blade, and are similar in size and shape to the aragonite needles reported for modern tropical carbonate factories. Seagrass calcification is a biological, light-enhanced process controlled by the leaf, and estimates of seagrass annual carbonate production in a Caribbean reef lagoon are as significant as values reported for Halimeda incrassata. Thus, we conclude that seagrass calcification is another biological source for the aragonite lime mud deposits found in tropical banks, and that tropical seagrass habitats may play a more important role in the oceanic carbon cycle than previously considered.

  10. Seagrass status and trends in the northern Gulf of Mexico: 1940-2002

    Science.gov (United States)

    Handley, L.; Altsman, D.; DeMay, R.

    2007-01-01

    Over the past century, seagrass habitats from the bays of Texas to the gulf shores of Florida have decreased. Seagrass beds, which are highly dependent on water quality and clarity for survival, are home to a multitude of aquatic plants and animals and a source of economic activity through commercial and recreational fishing and ecotourism. The U.S. Environmental Protection Agency’s Gulf of Mexico Program (GMP) and its partners have made a commitment to restore, enhance, and protect this important ecosystem. As seagrass habitats decrease, the need for information on the causes and effects of seagrass loss, current mapping information, and education on the importance of seagrassess becomes greater. This report is the initial effort of the GMP’s research and restoration plan for seagrasses. The purpose of this report is to provide scientists, managers, and citizens with valuable baseline information on the status and trends of seagrasses in coastal waters of the Gulf of Mexico. Within the northern Gulf of Mexico region, 14 individual estuarine systems where seagrasses occur, as well as statewide summaries for Texas, Louisiana, Mississippi, Alabama, and Florida, are examined in this study. Each estuarine system is detailed in vignettes that address current and historical extent and quality of seagrasses, seagrass mapping and monitoring, causes of status change, restoration and enhancement activities, background information for the entire study area as well as the subareas for study, and the methodology employed to analyze and document the historical trends and current status of seagrasses. The systems, moving from west to east, include the Laguna Madre, Texas Coastal Bend region, and Galveston Bay in Texas; the Chandeleur Islands in Louisiana; the Mississippi Sound; and Perdido Bay, Pensacola/Escambia Bay, Choctawhatchee Bay, St. Andrew Bay, Florida’s Big Bend region, Tampa Bay/St. Joseph Sound, Sarasota Bay, Greater Charlotte Harbor, and Florida Bay in Florida

  11. Carbon sources supporting benthic mineralization in mangrove and adjacent seagrass sediments (Gazi Bay, Kenya

    Directory of Open Access Journals (Sweden)

    F. Dehairs

    2004-08-01

    Full Text Available The origin of carbon substrates used by in situ sedimentary bacterial communities was investigated in an intertidal mangrove ecosystem and in adjacent seagrass beds in Gazi bay (Kenya by δ13C analysis of bacteria-specific PLFA (phospholipid fatty acids and bulk organic carbon. Export of mangrove-derived organic matter to the adjacent seagrass-covered bay was evident from sedimentary total organic carbon (TOC and δ13CTOC data. PLFA δ13C data indicate that the substrate used by bacterial communities varied strongly and that exported mangrove carbon was a significant source for bacteria in the adjacent seagrass beds. Within the intertidal mangrove forest, bacterial PLFA at the surface layer (0-1 cm typically showed more enriched δ13C values than deeper (up to 10 cm sediment layers, suggesting a contribution from microphytobenthos and/or inwelled seagrass material. Under the assumption that seagrasses and mangroves are the dominant potential end-members, the estimated contribution of mangrove-derived carbon to benthic mineralization in the seagrass beds (16-74% corresponds fairly well to the estimated contribution of mangrove C to the sedimentary organic matter pool (21-71% across different seagrass sites. Based on these results and a compilation of literature data, we suggest that allochtonous carbon trapped in seagrass beds may often represent a significant fraction of the substrate for benthic mineralization - both in cases where seagrass C dominates the sediment TOC pool and in cases where external inputs are significant. Hence, it is likely that community respiration data systematically overestimate the role of mineralization in the overall seagrass C budget.

  12. Seagrass-Watch: Engaging Torres Strait Islanders in marine habitat monitoring

    Science.gov (United States)

    Mellors, Jane E.; McKenzie, Len J.; Coles, Robert G.

    2008-09-01

    Involvement in scientifically structured habitat monitoring is a relatively new concept to the peoples of Torres Strait. The approach we used was to focus on awareness, and to build the capacity of groups to participate using Seagrass-Watch as the vehicle to provide education and training in monitoring marine ecosystems. The project successfully delivered quality scientifically rigorous baseline information on the seasonality of seagrasses in the Torres Strait—a first for this region. Eight seagrass species were identified across the monitoring sites. Seagrass cover varied within and between years. Preliminary evidence indicated that drivers for seagrass variability were climate related. Generally, seagrass abundance increased during the north-west monsoon ( Kuki), possibly a consequence of elevated nutrients, lower tidal exposure times, less wind, and higher air temperatures. Low seagrass abundance coincided with the presence of greater winds and longer periods of exposure at low tides during the south-east trade wind season ( Sager). No seasonal patterns were apparent when frequency of disturbance from high sedimentation and human impacts was high. Seagrass-Watch has been incorporated in to the Thursday Island High School's Marine Studies Unit ensuring continuity of monitoring. The students, teachers, and other interested individuals involved in Seagrass-Watch have mastered the necessary scientific procedures to monitor seagrass meadows, and developed skills in coordinating a monitoring program and skills in mentoring younger students. This has increased the participants' self-esteem and confidence, and given them an insight into how they may participate in the future management of their sea country.

  13. Carbon sources supporting benthic mineralization in mangrove and adjacent seagrass sediments (Gazi Bay, Kenya

    Directory of Open Access Journals (Sweden)

    S. Bouillon

    2004-01-01

    Full Text Available The origin of carbon substrates used by in situ sedimentary bacterial communities was investigated in an intertidal mangrove ecosystem and in adjacent seagrass beds in Gazi bay (Kenya by δ13C analysis of bacteria-specific PLFA (phospholipid fatty acids and bulk organic carbon. Export of mangrove-derived organic matter to the adjacent seagrass-covered bay was evident from sedimentary total organic carbon (TOC and δ13CTOC data. PLFA δ13C data indicate that the substrate used by bacterial communities varied strongly and that exported mangrove carbon was a significant source for bacteria in the adjacent seagrass beds. Within the intertidal mangrove forest, bacterial PLFA at the surface layer (0-1cm typically showed more enriched δ13C values than deeper (up to 10cm sediment layers, suggesting a contribution from microphytobenthos and/or inwelled seagrass material. Under the simplifying assumption that seagrasses and mangroves are the dominant potential end-members, the estimated contribution of mangrove-derived carbon to benthic mineralization in the seagrass beds (16-74% corresponds fairly well to the estimated contribution of mangrove C to the sedimentary organic matter pool (21-71% across different seagrass sites. Based on the results of this study and a compilation of literature data, we suggest that trapping of allochtonous C is a common feature in seagrass beds and often represents a significant source of C for sediment bacteria - both in cases where seagrass C dominates the sediment TOC pool and in cases where external inputs are significant. Hence, it is likely that data on community respiration rates systematically overestimate the role of in situ mineralization as a fate of seagrass production.

  14. Food supply depends on seagrass meadows in the coral triangle

    Science.gov (United States)

    Unsworth, Richard K. F.; Hinder, Stephanie L.; Bodger, Owen G.; Cullen-Unsworth, Leanne C.

    2014-09-01

    The tropical seascape provides food and livelihoods to hundreds of millions of people, but the support of key habitats to this supply remains ill appreciated. For fisheries and conservation management actions to help promote resilient ecosystems, sustainable livelihoods, and food supply, knowledge is required about the habitats that help support fisheries productivity and the consequences of this for food security. This paper provides an interdisciplinary case study from the coral triangle of how seagrass meadows provide support for fisheries and local food security. We apply a triangulated approach that utilizes ecological, fisheries and market data combined with over 250 household interviews. Our research demonstrates that seagrass associated fauna in a coral triangle marine protected area support local food supply contributing at least 50% of the fish based food. This formed between 54% and 99% of daily protein intake in the area. Fishery catch was found to significantly vary with respect to village (p type significantly influenced this proportion (<0.05). Limited sustainability of fishery practices (high juvenile catch and a 51% decline in CPUE for the biggest fishery) and poor habitat management mean the security of this food supply has the potential to be undermined in the long-term. Findings of this study have implications for the management and assessment of fisheries throughout the tropical seascape. Our study provides an exemplar for why natural resource management should move beyond biodiversity and consider how conservation and local food security are interlinked processes that are not mutually exclusive. Seagrass meadows are under sustained threat worldwide, this study provides evidence of the need to conserve these not just to protect biodiversity but to protect food security.

  15. Inhibition of Seagrass Photosynthesis by Ultraviolet-B Radiation 1

    Science.gov (United States)

    Trocine, Robert P.; Rice, John D.; Wells, Gary N.

    1981-01-01

    Effects of ultraviolet-B radiation on the photosynthesis of seagrasses (Halophila engelmanni Aschers, Halodule wrightii Aschers, and Syringodium filiforme Kütz) were examined. The intrinsic tolerance of each seagrass to ultraviolet-B, the presence and effectiveness of photorepair mechanisms to ultraviolet-B-induced photosynthetic inhibition, and the role of epiphytic growth as a shield from ultraviolet-B were investigated. Halodule was found to possess the greatest photosynthetic tolerance for ultraviolet-B. Photosynthesis in Syringodium was slightly more sensitive to ultraviolet-B while Halophila showed relatively little photosynthetic tolerance. Evidence for a photorepair mechanism was found only in Halodule. This mechanism effectively attenuated photosynthetic inhibition induced by ultraviolet-B dose rates and dosages in excess of natural conditions. Syringodium appeared to rely primarily on a thick epidermal cell layer to reduce photosynthetic damage. Halophila seemed to have no morphological or photorepair capabilities to deal with ultraviolet-B. This species appeared to rely on epiphytic and detrital shielding and the shade provided by other seagrasses to reduce ultraviolet-B irradiation to tolerable levels. The presence of epiphytes on leaf surfaces was found to reduce the extent of photosynthetic inhibition from ultraviolet-B exposure in all species. Observations obtained in this study seem to suggest the possibility of anthocyanin and/or other flavonoid synthesis as an adaptation to long term ultraviolet-B irradiation by these species. In addition, Halophila appears to obtain an increased photosynthetic tolerance to ultraviolet-B as an indirect benefit of chloroplast clumping to avoid photo-oxidation by intense levels of photosynthetically active radiation. Images PMID:16661893

  16. Inhibition of seagrass photosynthesis by ultraviolet-B radiation.

    Science.gov (United States)

    Trocine, R P; Rice, J D; Wells, G N

    1981-07-01

    Effects of ultraviolet-B radiation on the photosynthesis of seagrasses (Halophila engelmanni Aschers, Halodule wrightii Aschers, and Syringodium filiforme Kütz) were examined. The intrinsic tolerance of each seagrass to ultraviolet-B, the presence and effectiveness of photorepair mechanisms to ultraviolet-B-induced photosynthetic inhibition, and the role of epiphytic growth as a shield from ultraviolet-B were investigated.Halodule was found to possess the greatest photosynthetic tolerance for ultraviolet-B. Photosynthesis in Syringodium was slightly more sensitive to ultraviolet-B while Halophila showed relatively little photosynthetic tolerance. Evidence for a photorepair mechanism was found only in Halodule. This mechanism effectively attenuated photosynthetic inhibition induced by ultraviolet-B dose rates and dosages in excess of natural conditions. Syringodium appeared to rely primarily on a thick epidermal cell layer to reduce photosynthetic damage. Halophila seemed to have no morphological or photorepair capabilities to deal with ultraviolet-B. This species appeared to rely on epiphytic and detrital shielding and the shade provided by other seagrasses to reduce ultraviolet-B irradiation to tolerable levels. The presence of epiphytes on leaf surfaces was found to reduce the extent of photosynthetic inhibition from ultraviolet-B exposure in all species.Observations obtained in this study seem to suggest the possibility of anthocyanin and/or other flavonoid synthesis as an adaptation to long term ultraviolet-B irradiation by these species. In addition, Halophila appears to obtain an increased photosynthetic tolerance to ultraviolet-B as an indirect benefit of chloroplast clumping to avoid photo-oxidation by intense levels of photosynthetically active radiation.

  17. Solar radiation and tidal exposure as environmental drivers of Enhalus acoroides dominated seagrass meadows.

    Directory of Open Access Journals (Sweden)

    Richard K F Unsworth

    Full Text Available There is strong evidence of a global long-term decline in seagrass meadows that is widely attributed to anthropogenic activity. Yet in many regions, attributing these changes to actual activities is difficult, as there exists limited understanding of the natural processes that can influence these valuable ecosystem service providers. Being able to separate natural from anthropogenic causes of seagrass change is important for developing strategies that effectively mitigate and manage anthropogenic impacts on seagrass, and promote coastal ecosystems resilient to future environmental change. The present study investigated the influence of environmental and climate related factors on seagrass biomass in a large ≈250 ha meadow in tropical north east Australia. Annual monitoring of the intertidal Enhalus acoroides (L.f. Royle seagrass meadow over eleven years revealed a declining trend in above-ground biomass (54% significant overall reduction from 2000 to 2010. Partial Least Squares Regression found this reduction to be significantly and negatively correlated with tidal exposure, and significantly and negatively correlated with the amount of solar radiation. This study documents how natural long-term tidal variability can influence long-term seagrass dynamics. Exposure to desiccation, high UV, and daytime temperature regimes are discussed as the likely mechanisms for the action of these factors in causing this decline. The results emphasise the importance of understanding and assessing natural environmentally-driven change when interpreting the results of seagrass monitoring programs.

  18. The ecology of the seagrass meadows of the west coast of Florida: A community profile

    Energy Technology Data Exchange (ETDEWEB)

    Zieman, J.C.; Zieman, R.T. (Virginia Univ., Charlottesville, VA (USA). Dept. of Environmental Sciences)

    1989-09-01

    This report summarizes information on the ecology of seagrass meadows on the west coast of Florida, from south of Tampa Bay to Pensacola. This area contains more than 3500 ha of seagrass beds, dominated by three species, Thalasia testudinum (turtle grass), Syringodium filiforme (manatee grass), and Halodule wrightii (shoal grass). Beds occur both on the shallow, zero-energy Continental Shelf and in inshore bays and estuaries. Species ecology, distribution, biomass, and productivity of these dominant seagrass species are discussed. Seagrass beds support a very diverse and abundant algal flora and fauna, and these organisms, and seagrass detritus form the base of a productive food chain. Seagrass beds are important nursery areas providing both cover and food, for a number of commercial and sports fishery species. Along the west Florida coast, estuarine grass beds are noticeably more stressed and impacted by human activities than the more pristine nearshore beds. Urban development and dredging and filling are the major threates to seagrass beds in this region. 500 refs., 28 figs., 14 tabs.

  19. Acute and additive toxicity of ten photosystem-II herbicides to seagrass

    Science.gov (United States)

    Wilkinson, Adam D.; Collier, Catherine J.; Flores, Florita; Negri, Andrew P.

    2015-11-01

    Photosystem II herbicides are transported to inshore marine waters, including those of the Great Barrier Reef, and are usually detected in complex mixtures. These herbicides inhibit photosynthesis, which can deplete energy reserves and reduce growth in seagrass, but the toxicity of some of these herbicides to seagrass is unknown and combined effects of multiple herbicides on seagrass has not been tested. Here we assessed the acute phytotoxicity of 10 PSII herbicides to the seagrass Halophila ovalis over 24 and/or 48 h. Individual herbicides exhibited a broad range of toxicities with inhibition of photosynthetic activity (∆F/Fm‧) by 50% at concentrations ranging from 3.5 μg l-1 (ametryn) to 132 μg l-1 (fluometuron). We assessed potential additivity using the Concentration Addition model of joint action for binary mixtures of diuron and atrazine as well as complex mixtures of all 10 herbicides. The effects of both mixture types were largely additive, validating the application of additive effects models for calculating the risk posed by multiple PSII herbicides to seagrasses. This study extends seagrass ecotoxicological data to ametryn, metribuzin, bromacil, prometryn and fluometuron and demonstrates that low concentrations of PSII herbicide mixtures have the potential to impact ecologically relevant endpoints in seagrass, including ∆F/Fm‧.

  20. Photosynthetic response to globally increasing CO2 of co-occurring temperate seagrass species.

    Science.gov (United States)

    Borum, Jens; Pedersen, Ole; Kotula, Lukasz; Fraser, Matthew W; Statton, John; Colmer, Timothy D; Kendrick, Gary A

    2016-06-01

    Photosynthesis of most seagrass species seems to be limited by present concentrations of dissolved inorganic carbon (DIC). Therefore, the ongoing increase in atmospheric CO2 could enhance seagrass photosynthesis and internal O2 supply, and potentially change species competition through differential responses to increasing CO2 availability among species. We used short-term photosynthetic responses of nine seagrass species from the south-west of Australia to test species-specific responses to enhanced CO2 and changes in HCO3 (-) . Net photosynthesis of all species except Zostera polychlamys were limited at pre-industrial compared to saturating CO2 levels at light saturation, suggesting that enhanced CO2 availability will enhance seagrass performance. Seven out of the nine species were efficient HCO3 (-) users through acidification of diffusive boundary layers, production of extracellular carbonic anhydrase, or uptake and internal conversion of HCO3 (-) . Species responded differently to near saturating CO2 implying that increasing atmospheric CO2 may change competition among seagrass species if co-occurring in mixed beds. Increasing CO2 availability also enhanced internal aeration in the one species assessed. We expect that future increases in atmospheric CO2 will have the strongest impact on seagrass recruits and sparsely vegetated beds, because densely vegetated seagrass beds are most often limited by light and not by inorganic carbon.

  1. Solar radiation and tidal exposure as environmental drivers of Enhalus acoroides dominated seagrass meadows.

    Science.gov (United States)

    Unsworth, Richard K F; Rasheed, Michael A; Chartrand, Kathryn M; Roelofs, Anthony J

    2012-01-01

    There is strong evidence of a global long-term decline in seagrass meadows that is widely attributed to anthropogenic activity. Yet in many regions, attributing these changes to actual activities is difficult, as there exists limited understanding of the natural processes that can influence these valuable ecosystem service providers. Being able to separate natural from anthropogenic causes of seagrass change is important for developing strategies that effectively mitigate and manage anthropogenic impacts on seagrass, and promote coastal ecosystems resilient to future environmental change. The present study investigated the influence of environmental and climate related factors on seagrass biomass in a large ≈250 ha meadow in tropical north east Australia. Annual monitoring of the intertidal Enhalus acoroides (L.f.) Royle seagrass meadow over eleven years revealed a declining trend in above-ground biomass (54% significant overall reduction from 2000 to 2010). Partial Least Squares Regression found this reduction to be significantly and negatively correlated with tidal exposure, and significantly and negatively correlated with the amount of solar radiation. This study documents how natural long-term tidal variability can influence long-term seagrass dynamics. Exposure to desiccation, high UV, and daytime temperature regimes are discussed as the likely mechanisms for the action of these factors in causing this decline. The results emphasise the importance of understanding and assessing natural environmentally-driven change when interpreting the results of seagrass monitoring programs.

  2. Acute and additive toxicity of ten photosystem-II herbicides to seagrass.

    Science.gov (United States)

    Wilkinson, Adam D; Collier, Catherine J; Flores, Florita; Negri, Andrew P

    2015-11-30

    Photosystem II herbicides are transported to inshore marine waters, including those of the Great Barrier Reef, and are usually detected in complex mixtures. These herbicides inhibit photosynthesis, which can deplete energy reserves and reduce growth in seagrass, but the toxicity of some of these herbicides to seagrass is unknown and combined effects of multiple herbicides on seagrass has not been tested. Here we assessed the acute phytotoxicity of 10 PSII herbicides to the seagrass Halophila ovalis over 24 and/or 48 h. Individual herbicides exhibited a broad range of toxicities with inhibition of photosynthetic activity (∆F/F(m)') by 50% at concentrations ranging from 3.5 μg l(-1) (ametryn) to 132 μg l(-1) (fluometuron). We assessed potential additivity using the Concentration Addition model of joint action for binary mixtures of diuron and atrazine as well as complex mixtures of all 10 herbicides. The effects of both mixture types were largely additive, validating the application of additive effects models for calculating the risk posed by multiple PSII herbicides to seagrasses. This study extends seagrass ecotoxicological data to ametryn, metribuzin, bromacil, prometryn and fluometuron and demonstrates that low concentrations of PSII herbicide mixtures have the potential to impact ecologically relevant endpoints in seagrass, including ∆F/F(m)'.

  3. Mapping seagrass beds and coral reefs in the coastal region of Vietnam using VNREDSAT-1 data

    Science.gov (United States)

    Lau, K. V.; Chen, C. F.; Nguyen, S. T.; Chen, C. R.; Tong Phuoc, H. S.; Nguyen, H. H.

    2015-12-01

    Seagrass beds and coral reefs are two important ecosystems in the coastal zone. They play an important role to protect and shelter various marine organisms. Both seagrass beds and coral reefs could prevent the coastline from erosion. While seagrass stabilizes sediments and acts as a biofilter, coral reefs can control carbon dioxide in the ocean water. Besides, seagrass also provides direct food for many fish and marine animals. Therefore, mapping seagrass beds and coral reefs is very important for coastal management and conservation. In May 2013, Vietnam launched the first satellite for earth observations, called Vietnam Natural Resources, Environment and Disaster Monitoring Satellite (VNREDSAT-1). It is a great opportunity for environmental monitoring in the country using the data from this satellite. The objective of this study is to use the VNREDSAT-1 data to map seagrass beds and coral reefs in the coastal region of Ninh Hai district, Ninh Thuan province, Vietnam, where the seagrass still remains in good a condition. We processed the VNREDSAT-1 image through four steps: (1) Atmospheric correction using Second Simulation of the Satellite Signal in the Solar Spectrum radiative transfer model (6S), (2) Sun glint removal by using Hedley method, (3) Water column correction using the depth-variant index (DII) proposed by Lyzenga, and (4) Image classification using the maximum likelihood algorithm. The mapping results verified with the ground reference data showed a good overall accuracy of 75% and Kappa coefficient of 0.7. The total area of seagrass beds was approximately 323.09 ha, which mainly distributed in My Hoa and Thai An villages. The total area of coral reefs was approximately 564.42 ha, located along the coast and on outer area to seagrass and shoreline reefs. This study demonstrates the applicability of VNREDSAT-1 for underwater habitat monitoring. The results could be useful for natural resources managers to devise strategies for management and

  4. The potential impact of bedform migration on seagrass communities in Torres Strait, northern Australia

    Science.gov (United States)

    Daniell, James J.; Harris, Peter T.; Hughes, Michael G.; Hemer, Mark; Heap, Andrew

    2008-09-01

    Seagrass communities in the northwest of Torres Strait are known to disappear episodically over broad areas. Sediment mobility surveys were undertaken within two study areas during the monsoon and trade wind seasons, in the vicinity of Turnagain Island, to find out if the migration of bedforms could explain this disappearance. The two study areas covered sand bank and sand dune environments to compare and contrast their migration characteristics. Repeat multibeam sonar surveys were used to measure dune-crest migration during each season. Our results show that seagrass beds occur in the troughs of sediment-starved dunes, but no seagrass occurs in association with full-bedded dunes that are superimposed on large sand bank features. The coincidence of seagrass beds with the sediment-starved dunes is in spite of the fact that they migrate faster (0.59 m day -1) than full-bedded dunes (0.13 m day -1), which indicates that some other factor (other than dune migration rate) limits seagrass growth within Torres Strait. We suggest that seagrasses are unable to colonise full-bedded dunes because of the semi-continuously transported sand that characterises this environment. In contrast, the troughs of sediment-starved dunes experience only limited bedload transport and are less hostile for seagrasses. A conceptual model is presented to explain the occurrence of seagrass beds in relation to their proximity to migrating sand dunes. Based on our analysis, we conclude that the widespread dieback of seagrasses documented for the Turnagain Island region was not caused by dune migration.

  5. Development of a DNA barcoding system for seagrasses: successful but not simple.

    Directory of Open Access Journals (Sweden)

    Christina Lucas

    Full Text Available Seagrasses, a unique group of submerged flowering plants, profoundly influence the physical, chemical and biological environments of coastal waters through their high primary productivity and nutrient recycling ability. They provide habitat for aquatic life, alter water flow, stabilize the ground and mitigate the impact of nutrient pollution. at the coast region. Although on a global scale seagrasses represent less than 0.1% of the angiosperm taxa, the taxonomical ambiguity in delineating seagrass species is high. Thus, the taxonomy of several genera is unsolved. While seagrasses are capable of performing both, sexual and asexual reproduction, vegetative reproduction is common and sexual progenies are always short lived and epimeral in nature. This makes species differentiation often difficult, especially for non-taxonomists since the flower as a distinct morphological trait is missing. Our goal is to develop a DNA barcoding system assisting also non-taxonomists to identify regional seagrass species. The results will be corroborated by publicly available sequence data. The main focus is on the 14 described seagrass species of India, supplemented with seagrasses from temperate regions. According to the recommendations of the Consortium for the Barcoding of Life (CBOL rbcL and matK were used in this study. After optimization of the DNA extraction method from preserved seagrass material, the respective sequences were amplified from all species analyzed. Tree- and character-based approaches demonstrate that the rbcL sequence fragment is capable of resolving up to family and genus level. Only matK sequences were reliable in resolving species and partially the ecotype level. Additionally, a plastidic gene spacer was included in the analysis to confirm the identification level. Although the analysis of these three loci solved several nodes, a few complexes remained unsolved, even when constructing a combined tree for all three loci. Our approaches

  6. Seagrass response to CO₂ contingent on epiphytic algae: indirect effects can overwhelm direct effects.

    Science.gov (United States)

    Burnell, Owen W; Russell, Bayden D; Irving, Andrew D; Connell, Sean D

    2014-11-01

    Increased availability of dissolved CO2 in the ocean can enhance the productivity and growth of marine plants such as seagrasses and algae, but realised benefits may be contingent on additional conditions (e.g. light) that modify biotic interactions between these plant groups. The combined effects of future CO2 and differing light on the growth of seagrass and their algal epiphytes were tested by maintaining juvenile seagrasses Amphibolis antarctica under three different CO2 concentrations representing ambient, moderate future and high future forecasts (i.e. 390, 650 vs. 900 µl l(-1)) and two light levels representing low and high PAR (i.e. 43 vs. 167 µmol m(-2) s(-1)). Aboveground and belowground biomass, leaf growth, epiphyte cover, tissue chemistry and photosynthetic parameters of seagrasses were measured. At low light, there was a neutral to positive effect of elevated CO2 on seagrass biomass and growth; at high light, this effect of CO2 switched toward negative, as growth and biomass decreased at the highest CO2 level. These opposing responses to CO2 appeared to be closely linked to the overgrowth of seagrass by filamentous algal epiphytes when high light and CO2 were combined. Importantly, all seagrass plants maintained positive leaf growth throughout the experiment, indicating that growth was inhibited by some experimental conditions but not arrested entirely. Therefore, while greater light or elevated CO2 provided direct physiological benefits for seagrasses, such benefits were likely negated by overgrowth of epiphytic algae when greater light and CO2 were combined. This result demonstrates how indirect ecological effects from epiphytes can modify independent physiological predictions for seagrass associated with global change.

  7. The short-term impacts of a cyclone on seagrass communities in Southwest Madagascar

    Science.gov (United States)

    Côté-Laurin, Marie-Claude; Benbow, Sophie; Erzini, Karim

    2017-04-01

    Cyclones are large-scale disturbances with highly destructive potential in coastal ecosystems. On February 22, 2013, a powerful tropical cyclone made landfall on the southwest coast of Madagascar, a region which is infrequently hit by such extreme weather events coming from the Mozambique Channel. Seagrass ecosystems, which provide valuable ecosystems services to local communities, are especially vulnerable because they thrive in shallow waters. The impact of Cyclone Haruna on seagrass diversity, height and coverage and associated fish diversity, abundance and biomass was assessed in 3 sites near Andavadoaka (22°07‧S, 43°23‧E) before and after the event using fish underwater visual census, video-transects, and seagrass quadrats. The cyclone caused a significant loss in seagrass cover at all 3 sites. Thalassia hemprichii and Syringodium isoetifolium were the most affected species. Andavadoaka beach, the most exposed site, which was also subject to human use and was most fragmented, suffered the largest negative effects of the cyclone. Cyclone Haruna was not found to significantly affect fish assemblages, which are highly mobile organisms able to use a diversity of niches and adjacent habitats after seagrass fragmentation. Extensive sampling and longer time-scale studies would be needed to fully evaluate the cyclone impact on communities of seagrass and fish, and track potential recovery in seagrass coverage. The intensity and destructive potential of cyclones is expected to increase with global warming, which is of concern for developing countries that encompass most of the world's seagrass beds. This study provided a unique and key opportunity to monitor immediate impacts of an extreme disturbance in a region where cyclones rarely hit coastal ecosystems and where local populations remain highly dependent on seagrass meadows.

  8. Mediterranean “regionalism"

    DEFF Research Database (Denmark)

    Pace, Michelle

    2017-01-01

    The concept of the Mediterranean ‘region’ has been contested both theoretically and empirically time and again. But, what are its current meanings if any? What do the never-ending internal divisions between and within countries in this imagined space tell us about the state of the Mediterranean t...

  9. Hurricane Paloma’s effects on seagrasses along Jardines de la Reina archipelago, Cuba

    OpenAIRE

    2013-01-01

    Seagrasses are one of the most important coastal ecosystems since they promote organic matter flow, nutrient cycling, food availability and refuge. Until now, reports on damages caused by storms and hurricanes on seagrass beds are uncommon and highly variable. The seagrass meadows of the East end of Jardines de la Reina archipelago were surveyed from Nov. 29th to Dec. 5th of 2008, in order to determinate the effects from the passing of Hurricane Paloma: a category three storm on the Saffir-Si...

  10. Chlorophyll content, productivities and biomass allocations of seagrasses in Talim Bay, Lian, Batangas, Philippines

    Directory of Open Access Journals (Sweden)

    Michael A. Clores

    2013-09-01

    Full Text Available This study determined the chlorophyll content, productivities and biomass allocations of three abundant species of seagrasses in Talim Bay, Lian, Batangas. Philippines: Enhalus acoroides, Cymodocea rotundata, and Thalassia hemprichii. Four seagrass meadows in the bay were selected based on their terrestrial sources of nutrient loads. Results reveal that seagrasses at South Matuod (a site which receives nutrient load drained mostly from corn- and cane-fields, yields the highest GPP (Gross Primary Productivity, but R (Respiration is higher than GPP, and therefore NPP (Net Primary Productivity was negative. The same pattern of productivity values were observed in the other sites implying that seagrasses were not making enough oxygen for their life processes at the time of the study (October to November 2010. Although the NPP of seagrasses was negative in Talim Point, (a site which does not receive nutrient load from terrestrial area serving as the control site, they had the highest chlorophyll a and b content with the other sites. R in this site is the lowest despite its low GPP, suggesting a more efficient primary production. Seagrasses in Kayreyna (which receives nutrient load from primarily from sewerage as well as farmland, i.e., near one creek that drains houses had the highest total average Wet weight (WW, Dry Weight (DW and Ash-Free Dry Weight (AFDW while those seagrasses collected in South Matuod had the lowest biomass. The low biomass of seagrasses in Matuod could be related to their very low productivity and low chlorophyll content needed for such production. Kayreyna is characterized by seagrasses with second highest chlorophyll content after Talim point, and in terms of productivity, two of seagrass species in this site E. acoroides and T. hemprichii are among those with the lowest R. Evidently, seagrasses in Talim Point, Shields Marine Station (the site which receives primarily agriculture run-off, i.e., near a creek that drains mostly

  11. Genetic connectivity between land and sea: the case of the beachflea Orchestia montagui (Crustacea, Amphipoda, Talitridae) in the Mediterranean Sea.

    Science.gov (United States)

    Pavesi, Laura; Tiedemann, Ralph; De Matthaeis, Elvira; Ketmaier, Valerio

    2013-04-25

    We examined patterns of genetic divergence in 26 Mediterranean populations of the semi-terrestrial beachflea Orchestia montagui using mitochondrial (cytochrome oxidase subunit I), microsatellite (eight loci) and allozymic data. The species typically forms large populations within heaps of dead seagrass leaves stranded on beaches at the waterfront. We adopted a hierarchical geographic sampling to unravel population structure in a species living at the sea-land transition and, hence, likely subjected to dramatically contrasting forces. Mitochondrial DNA showed historical phylogeographic breaks among Adriatic, Ionian and the remaining basins (Tyrrhenian, Western and Eastern Mediterranean Sea) likely caused by the geological and climatic changes of the Pleistocene. Microsatellites (and to a lesser extent allozymes) detected a further subdivision between and within the Western Mediterranean and the Tyrrhenian Sea due to present-day processes. A pattern of isolation by distance was not detected in any of the analyzed data set. We conclude that the population structure of O. montagui is the result of the interplay of two contrasting forces that act on the species population genetic structure. On one hand, the species semi-terrestrial life style would tend to determine the onset of local differences. On the other hand, these differences are partially counter-balanced by passive movements of migrants via rafting on heaps of dead seagrass leaves across sites by sea surface currents. Approximate Bayesian Computations support dispersal at sea as prevalent over terrestrial regionalism.

  12. Back to the sea twice: identifying candidate plant genes for molecular evolution to marine life

    Directory of Open Access Journals (Sweden)

    Reusch Thorsten BH

    2011-01-01

    Full Text Available Abstract Background Seagrasses are a polyphyletic group of monocotyledonous angiosperms that have adapted to a completely submerged lifestyle in marine waters. Here, we exploit two collections of expressed sequence tags (ESTs of two wide-spread and ecologically important seagrass species, the Mediterranean seagrass Posidonia oceanica (L. Delile and the eelgrass Zostera marina L., which have independently evolved from aquatic ancestors. This replicated, yet independent evolutionary history facilitates the identification of traits that may have evolved in parallel and are possible instrumental candidates for adaptation to a marine habitat. Results In our study, we provide the first quantitative perspective on molecular adaptations in two seagrass species. By constructing orthologous gene clusters shared between two seagrasses (Z. marina and P. oceanica and eight distantly related terrestrial angiosperm species, 51 genes could be identified with detection of positive selection along the seagrass branches of the phylogenetic tree. Characterization of these positively selected genes using KEGG pathways and the Gene Ontology uncovered that these genes are mostly involved in translation, metabolism, and photosynthesis. Conclusions These results provide first insights into which seagrass genes have diverged from their terrestrial counterparts via an initial aquatic stage characteristic of the order and to the derived fully-marine stage characteristic of seagrasses. We discuss how adaptive changes in these processes may have contributed to the evolution towards an aquatic and marine existence.

  13. Detection of Seagrass Distribution Changes from 1991 to 2006 in Xincun Bay, Hainan, with Satellite Remote Sensing

    Directory of Open Access Journals (Sweden)

    Chaoyu Yang

    2009-02-01

    Full Text Available Seagrass distribution is a very important index for costal management and protection. Seagrass distribution changes can be used as indexes to analyze the reasons for the changes. In this paper, in situ hyperspectral observation and satellite images of QuickBird, CBERS (China Brazil Earth Resources Satellite data and Landsat data were used to retrieve bio-optical models and seagrass (Enhalus acoroides,Thalassia hemperichii distribution in Xincun Bay, Hainan province, and seagrass distribution changes from 1991 to 2006 were analyzed. Hyperspectral results showed that the spectral bands at 555, 635, 650 and 675 nm are sensitive to leaf area index (LAI. Seagrass detection with QuickBird was more accurate than that with Landsat TM and CBERS; five classes could be classified clearly and used as correction for seagrass remote sensing data from Landsat TM and CBERS. In order to better describe seagrass distribution changes, the seagrass distribution area was divided as three regions: region A connected with region B in 1991, however it separated in 1999 and was wholly separated in 2001; seagrass in region C shrank gradually and could not be detected in 2006. Analysis of the reasons for seagrass reduction indicated it was mainly affected by aquaculture and typhoons and in recent years, by land use changes.

  14. Detection of seagrass distribution changes from 1991 to 2006 in xincun bay, hainan, with satellite remote sensing.

    Science.gov (United States)

    Yang, Dingtian; Yang, Chaoyu

    2009-01-01

    Seagrass distribution is a very important index for costal management and protection. Seagrass distribution changes can be used as indexes to analyze the reasons for the changes. In this paper, in situ hyperspectral observation and satellite images of QuickBird, CBERS (China Brazil Earth Resources Satellite data) and Landsat data were used to retrieve bio-optical models and seagrass (Enhalus acoroides, Thalassia hemperichii) distribution in Xincun Bay, Hainan province, and seagrass distribution changes from 1991 to 2006 were analyzed. Hyperspectral results showed that the spectral bands at 555, 635, 650 and 675 nm are sensitive to leaf area index (LAI). Seagrass detection with QuickBird was more accurate than that with Landsat TM and CBERS; five classes could be classified clearly and used as correction for seagrass remote sensing data from Landsat TM and CBERS. In order to better describe seagrass distribution changes, the seagrass distribution area was divided as three regions: region A connected with region B in 1991, however it separated in 1999 and was wholly separated in 2001; seagrass in region C shrank gradually and could not be detected in 2006. Analysis of the reasons for seagrass reduction indicated it was mainly affected by aquaculture and typhoons and in recent years, by land use changes.

  15. Seagrass ecophysiological performance under ocean warming and acidification.

    Science.gov (United States)

    Repolho, Tiago; Duarte, Bernardo; Dionísio, Gisela; Paula, José Ricardo; Lopes, Ana R; Rosa, Inês C; Grilo, Tiago F; Caçador, Isabel; Calado, Ricardo; Rosa, Rui

    2017-02-01

    Seagrasses play an essential ecological role within coastal habitats and their worldwide population decline has been linked to different types of anthropogenic forces. We investigated, for the first time, the combined effects of future ocean warming and acidification on fundamental biological processes of Zostera noltii, including shoot density, leaf coloration, photophysiology (electron transport rate, ETR; maximum PSII quantum yield, Fv/Fm) and photosynthetic pigments. Shoot density was severely affected under warming conditions, with a concomitant increase in the frequency of brownish colored leaves (seagrass die-off). Warming was responsible for a significant decrease in ETR and Fv/Fm (particularly under control pH conditions), while promoting the highest ETR variability (among experimental treatments). Warming also elicited a significant increase in pheophytin and carotenoid levels, alongside an increase in carotenoid/chlorophyll ratio and De-Epoxidation State (DES). Acidification significantly affected photosynthetic pigments content (antheraxanthin, β-carotene, violaxanthin and zeaxanthin), with a significant decrease being recorded under the warming scenario. No significant interaction between ocean acidification and warming was observed. Our findings suggest that future ocean warming will be a foremost determinant stressor influencing Z. noltii survival and physiological performance. Additionally, acidification conditions to occur in the future will be unable to counteract deleterious effects posed by ocean warming.

  16. Seagrass ecophysiological performance under ocean warming and acidification

    Science.gov (United States)

    Repolho, Tiago; Duarte, Bernardo; Dionísio, Gisela; Paula, José Ricardo; Lopes, Ana R.; Rosa, Inês C.; Grilo, Tiago F.; Caçador, Isabel; Calado, Ricardo; Rosa, Rui

    2017-01-01

    Seagrasses play an essential ecological role within coastal habitats and their worldwide population decline has been linked to different types of anthropogenic forces. We investigated, for the first time, the combined effects of future ocean warming and acidification on fundamental biological processes of Zostera noltii, including shoot density, leaf coloration, photophysiology (electron transport rate, ETR; maximum PSII quantum yield, Fv/Fm) and photosynthetic pigments. Shoot density was severely affected under warming conditions, with a concomitant increase in the frequency of brownish colored leaves (seagrass die-off). Warming was responsible for a significant decrease in ETR and Fv/Fm (particularly under control pH conditions), while promoting the highest ETR variability (among experimental treatments). Warming also elicited a significant increase in pheophytin and carotenoid levels, alongside an increase in carotenoid/chlorophyll ratio and De-Epoxidation State (DES). Acidification significantly affected photosynthetic pigments content (antheraxanthin, β-carotene, violaxanthin and zeaxanthin), with a significant decrease being recorded under the warming scenario. No significant interaction between ocean acidification and warming was observed. Our findings suggest that future ocean warming will be a foremost determinant stressor influencing Z. noltii survival and physiological performance. Additionally, acidification conditions to occur in the future will be unable to counteract deleterious effects posed by ocean warming. PMID:28145531

  17. Seagrass ecophysiological performance under ocean warming and acidification

    Science.gov (United States)

    Repolho, Tiago; Duarte, Bernardo; Dionísio, Gisela; Paula, José Ricardo; Lopes, Ana R.; Rosa, Inês C.; Grilo, Tiago F.; Caçador, Isabel; Calado, Ricardo; Rosa, Rui

    2017-02-01

    Seagrasses play an essential ecological role within coastal habitats and their worldwide population decline has been linked to different types of anthropogenic forces. We investigated, for the first time, the combined effects of future ocean warming and acidification on fundamental biological processes of Zostera noltii, including shoot density, leaf coloration, photophysiology (electron transport rate, ETR; maximum PSII quantum yield, Fv/Fm) and photosynthetic pigments. Shoot density was severely affected under warming conditions, with a concomitant increase in the frequency of brownish colored leaves (seagrass die-off). Warming was responsible for a significant decrease in ETR and Fv/Fm (particularly under control pH conditions), while promoting the highest ETR variability (among experimental treatments). Warming also elicited a significant increase in pheophytin and carotenoid levels, alongside an increase in carotenoid/chlorophyll ratio and De-Epoxidation State (DES). Acidification significantly affected photosynthetic pigments content (antheraxanthin, β-carotene, violaxanthin and zeaxanthin), with a significant decrease being recorded under the warming scenario. No significant interaction between ocean acidification and warming was observed. Our findings suggest that future ocean warming will be a foremost determinant stressor influencing Z. noltii survival and physiological performance. Additionally, acidification conditions to occur in the future will be unable to counteract deleterious effects posed by ocean warming.

  18. Distribution and community structure of ichthyoplankton in Laguna Madre seagrass meadows: Potential impact of seagrass species change

    Science.gov (United States)

    Tolan, J.M.; Holt, S.A.; Onuf, C.P.

    1997-01-01

    Seasonal ichthyoplankton surveys were made in the lower Laguna Madre, Texas, to compare the relative utilization of various nursery habitats (shoal grass, Halodule wrightii; manatee grass, Syringodium filiforme;, and unvegetated sand bottom) for both estuarine and offshore-spawned larvae. The species composition and abundance of fish larvae were determined for each habitat type at six locations in the bay. Pushnet ichthyoplankton sampling resulted in 296 total collections, yielding 107,463 fishes representing 55 species in 24 families. A broad spectrum of both the biotic and physical habitat parameters were examined to link the dispersion and distribution of both pre-settlement and post-settlement larvae to the utilization of shallow seagrass habitats. Sample sites were grouped by cluster analysis (Ward's minimum variance method) according to the similarity of their fish assemblages and subsequently examined with a multiple discriminant function analysis to identify important environmental variables. Abiotic environmental factors were most influential in defining groups for samples dominated by early larvae, whereas measures of seagrass complexity defined groups dominated by older larvae and juveniles. Juvenile-stage individuals showed clear habitat preference, with the more shallow Halodule wrightii being the habitat of choice, whereas early larvae of most species were widely distributed over all habitats. As a result of the recent shift of dominance from Halodule wrightii to Syringodium filiforme, overall reductions in the quality of nursery habitat for fishes in the lower Laguna Madre are projected.

  19. Public Seagrass Compilation for West Coast Essential Fish Habitat (EFH) Environmental Impact Statement

    Data.gov (United States)

    Pacific States Marine Fisheries Commission — These data are a compilation of currently available seagrass GIS data sets for the west coast of the United States. These data have been compiled from seventeen...

  20. Seagrass habitat complexity and macroinvertebrate abundance in Lakshadweep coral reef lagoons, Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A.; Rivonker, C.U.; Ramani, P.; Parulekar, A.H.

    Macrofauna of seagrass community in the five Lakshadweep atolls were studied and compared. The associated epifaunal and infaunal taxa comprising nine major taxonomic groups, showed significant differences in the total number of individuals (1041...

  1. Palm Beach County FL 2007 Seagrass GIS Maps and Trends Analysis (NODC Accession 0061752)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Geographic Information System (GIS) coverage of Palm Beach County seagrasses, mangrove habitat, oyster reef, and spartina. The mapped area is the Lake Worth Lagoon...

  2. Anthropogenic chemicals as drivers of change for coastal ecosystems: wetlands, mangroves and seagrass habitats.

    Science.gov (United States)

    Coastal wetlands, mangrove and seagrass habitats are rapidly declining worldwide which reduces their many ecological services. This presentation summarizes the results of a literature survey conducted to determine scientific understanding of contaminant uptake and toxicity of non...

  3. Processes affecting the spatial distribution of seagrass meadow sedimentary material on Yao Yai Island, Thailand

    NARCIS (Netherlands)

    Quak, M.S.Y.; Ziegler, A.D.; Benner, S.G.; Evans, S.; Todd, P.A.; Gillis, L.G.; Vongtanaboon, S.; Jachowski, N.; Bouma, T.J.

    2016-01-01

    Many islands throughout SE Asia are experiencing rapid development and land-cover conversion thatpotentially threaten sensitive coastal ecosystems, such as seagrasses, through increased loading ofsediment and nutrients originating from disturbed catchments draining to the sea. To evaluate this threa

  4. Development of an epiphyte indicator of nutrient enrichment: Threshold values for seagrass epiphyte load

    Science.gov (United States)

    Metrics of epiphyte load on macrophytes were evaluated for use as quantitative biological indicators for nutrient impacts in estuarine waters, based on review and analysis of the literature on epiphytes and macrophytes, primarily seagrasses, but including some brackish and freshw...

  5. A geospatial modelling approach to predict seagrass habitat recovery under multiple stressor regimes

    Science.gov (United States)

    Restoration of estuarine seagrass habitats requires a clear understanding of the modes of action of multiple interacting stressors including nutrients, climate change, coastal land-use change, and habitat modification. We have developed and demonstrated a geospatial modeling a...

  6. Cover versus recovery: contrasting responses of two indicators in seagrass beds.

    Science.gov (United States)

    Soissons, Laura M; Han, Qiuying; Li, Baoquan; van Katwijk, Marieke M; Ysebaert, Tom; Herman, Peter M J; Bouma, Tjeerd J

    2014-10-15

    Despite being a highly valuable key-stone ecosystem, seagrass meadows are threatened and declining worldwide, creating urgent need for indicators of their health status. We compared two indicators for seagrass health: standing leaf area index versus relative recovery from local disturbance. Disturbance was created by removing aboveground biomass and recording the rate of regrowth for Zostera marina meadows exposed to contrasting wave regimes and nutrient stress levels. Within the experimental period, relative regrowth in gaps was around 50% in most plots, except for the ambient nutrient treatment at the sheltered site, where it exceeded 100%. The two indicators showed an opposite response to disturbance: the higher the standing leaf area index, the lower the relative recovery from disturbance. This conflicting response raises the question on the proper interpretation of such indicators to estimate seagrass health and resilience, and how to ideally monitor seagrass ecosystems in order to predict collapse.

  7. Combined nutrient and macroalgae loads lead to response in seagrass indicator properties.

    Science.gov (United States)

    Han, Qiuying; Soissons, Laura M; Bouma, Tjeerd J; van Katwijk, Marieke M; Liu, Dongyan

    2016-05-15

    Excess nutrients are potential factors that drive phase shifts from seagrasses to macroalgae. We carried out a manipulative field experiment to study the effects of macroalgae Ulva pertusa loading and nutrient addition to the water column on the nitrogen (N) and carbon (C) contents (i.e., fast indicators) as well as on the morphology and structure (i.e., slow indicators) of Zostera marina. Our results showed rapid impact of increased macroalgae and nutrient load on Z. marina C/N ratios. Also, macroalgae addition resulted in a trend of decreasing belowground biomass of seagrasses, and nutrient load significantly decreased above to belowground biomass ratio. Although some morphological/structural variables showed relatively fast responses, the effects of short-term disturbance by macroalgae and nutrients were less often significant than on physiological variables. Monitoring of seagrass physiological indicators may allow for early detection of eutrophication, which may initiate timely management interventions to avert seagrass loss.

  8. Mapping seagrass coverage and spatial patterns with high spatial resolution IKONOS imagery

    Science.gov (United States)

    Pu, Ruiliang; Bell, Susan

    2017-02-01

    Seagrass habitats in subtidal coastal waters provide a variety of ecosystem functions and services and there is an increasing need to acquire information on spatial and temporal dynamics of this resource. Here, we explored the capability of IKONOS (IKO) data of high resolution (4 m) for mapping seagrass cover [submerged aquatic vegetation (%SAV) cover] along the mid-western coast of Florida, USA. We also compared seagrass maps produced with IKO data with that obtained using the Landsat TM sensor with lower resolution (30 m). Both IKO and TM data, collected in October 2009, were preprocessed to calculate water depth invariant bands to normalize the effect of varying depth on bottom spectra recorded by the two satellite sensors and further the textural information was extracted from IKO data. Our results demonstrate that the high resolution IKO sensor produced a higher accuracy than the TM sensor in a three-class % SAV cover classification. Of note is that the OA of %SAV cover mapping at our study area created with IKO data was 5-20% higher than that from other studies published. We also examined the spatial distribution of seagrass over a spatial range of 4-240 m using the Ripley's K function [L(d)] and IKO data that represented four different grain sizes [4 m (one IKO pixel), 8 m (2 × 2 IKO pixels), 12 m (3 × 3 IKO pixels), and 16 m (4 × 4 IKO pixels)] from moderate-dense seagrass cover along a set of six transects. The Ripley's K metric repeatedly indicated that seagrass cover representing 4 m × 4 m pixels displayed a dispersed (or slightly dispersed) pattern over distances of pattern of cover over 9-240 m. The spatial pattern of seagrass cover created with the three additional grain sizes (i.e., 2 × 24 m IKO pixels, 3 × 34 m IKO pixels, and 4 × 4 m IKO pixels) show a dispersed (or slightly dispersed) pattern across 4-32 m and a random or slightly clustered pattern across 33-240 m. Given the first report on using satellite observations to quantify seagrass

  9. Developing a methodology of bioindication of human-induced effects using seagrass morphological variation in Spermonde Archipelago, South Sulawesi, Indonesia.

    Science.gov (United States)

    Ambo-Rappe, Rohani

    2014-09-15

    Seagrass is particularly susceptible to environmental degradation. The objective of the study is to develop an effective bioindicator to assess human-induced effects using morphological variation and fluctuating asymmetry (FA) of seagrass. Samples were collected from eight islands situated at different distance from mainland with different human population density and therefore expected to experience different level of anthropogenic pressure. Cd, Pb, Cu, Zn, nitrate, and phosphate were measured. Metals were also measured in tissues of seagrass. Metal concentrations in sediment, water, and seagrass did not exceed the quality standards required for marine life. Heterogeneity of FA was found among sites suggesting that there are some factors changing developmental instability of seagrass which is not associated to particular toxicants. This baseline study indicates that the water condition is still natural and shows no signs of metal contamination, therefore it does not cause a detectable stress on morphological variation and FA of seagrass.

  10. The degree of urbanization across the globe is not reflected in the δ(15)N of seagrass leaves.

    Science.gov (United States)

    Christiaen, Bart; Bernard, Rebecca J; Mortazavi, Behzad; Cebrian, Just; Ortmann, Alice C

    2014-06-30

    Many studies show that seagrass δ(15)N ratios increase with the amount of urbanization in coastal watersheds. However, there is little information on the relationship between urbanization and seagrass δ(15)N ratios on a global scale. We performed a meta-analysis on seagrass samples from 79 independent locations to test if seagrass δ(15)N ratios correlate with patterns of population density and fertilizer use within a radius of 10-200 km around the sample locations. Our results show that seagrass δ(15)N ratios are more influenced by intergeneric and latitudinal differences than the degree of urbanization or the amount of fertilizer used in nearby watersheds. The positive correlation between seagrass δ(15)N ratios and latitude hints at an underlying pattern in discrimination or a latitudinal gradient in the (15)N isotopic signature of nitrogen assimilated by the plants. The actual mechanisms responsible for the correlation between δ(15)N and latitude remain unknown.

  11. Seagrass burial by dredged sediments: benthic community alteration, secondary production loss, biotic index reaction and recovery possibility.

    Science.gov (United States)

    Tu Do, V; de Montaudouin, Xavier; Blanchet, Hugues; Lavesque, Nicolas

    2012-11-01

    In 2005, dredging activities in Arcachon Bay (France) led in burying 320,000 m(2) of Zostera noltii intertidal seagrass. Recovery by macrobenthos and seagrass was monitored. Six months after works, seagrass was absent and macrobenthos drastically different from surrounding vegetated stations. Rapidly and due to sediment dispersal, disposal area was divided into a sandflat with a specific benthic community which maintained its difference until the end of the survey (2010), and a mudflat where associated fauna became similar to those in adjacent seagrass. Macrobenthic community needs 3 years to recover while seagrass needs 5 years to recover in the station impacted by mud. The secondary production loss due to works was low. In this naturally carbon enriched system, univariate biotic indices did not perform well to detect seagrass destruction and recovery. Multivariate index MISS gave more relevant conclusions and a simplified version was tested with success, at this local scale.

  12. Humans and Seagrasses in East Africa : A social-ecological systems approach

    OpenAIRE

    de la Torre-Castro, Maricela

    2006-01-01

    The present study is one of the first attempts to analyze the societal importance of seagrasses (marine flowering plants) from a Natural Resource Management perspective, using a social-ecological systems (SES) approach. The interdisciplinary study takes place in East Africa (Western Indian Ocean, WIO) and includes in-depth studies in Chwaka Bay, Zanzibar, Tanzania. Natural and social sciences methods were used. The results are presented in six articles, showing that seagrass ecosystems are ri...

  13. Characterization of Available Light for Seagrass and Patch Reef Productivity in Sugarloaf Key, Lower Florida Keys

    OpenAIRE

    2016-01-01

    Light availability is an important factor driving primary productivity in benthic ecosystems, but in situ and remote sensing measurements of light quality are limited for coral reefs and seagrass beds. We evaluated the productivity responses of a patch reef and a seagrass site in the Lower Florida Keys to ambient light availability and spectral quality. In situ optical properties were characterized utilizing moored and water column bio-optical and hydrographic measurements. Net ecosystem prod...

  14. The role of seagrass-associated resources in an estuarine benthic food web

    OpenAIRE

    Vafeiadou, Anna-Maria; Materatski, Patrick; Adão, Helena; Troch, Marleen; Moens, Tom

    2014-01-01

    Benthos have a key role in marine food webs by linking primary production to higher trophic levels, enhancing energy and nutrient transfer between the sediments and the pelagic zone. In seagrass ecosystems trophic relations are complex due to large resource variability. This study focuses on the benthic food web in a Zostera noltii seagrass habitat (Mira Estuary, Portugal). We examined resource utilization of the most abundant macroand meiobenthic taxa at genus, species or fami...

  15. Evaluation of aboveground and belowground biomass recovery in physically disturbed seagrass beds.

    Science.gov (United States)

    Di Carlo, Giuseppe; Kenworthy, W Judson

    2008-11-01

    Several studies addressed aboveground biomass recovery in tropical and subtropical seagrass systems following physical disturbance. However, there are few studies documenting belowground biomass recovery despite the important functional and ecological role of roots and rhizomes for seagrass ecosystems. In this study, we compared the recovery of biomass (g dry weight m(-2)) as well as the biomass recovery rates in ten severely disturbed multi-species seagrass meadows, after the sediments were excavated and the seagrasses removed. Three sites were located in the tropics (Puerto Rico) and seven in the subtropics (Florida Keys), and all were originally dominated by Thalassia testudinum. Total aboveground biomass reached reference values at four out of ten sites studied, two in the Florida Keys and two in Puerto Rico. Total belowground biomass was lower at the disturbed locations compared to the references at all sites, apart from two sites in the Florida Keys where the compensatory effect of opportunistic species (Syringodium filiforme and Halodule wrightii) was observed. The results revealed large variation among sites in aboveground and belowground biomass for all species, with higher aboveground recovery than belowground for T. testudinum. Recovery rates for T. testudinum were highly variable across sites, but a general trend of faster aboveground than belowground recovery was observed. Equal rates between aboveground and belowground biomass were found for opportunistic species at several sites in the Florida Keys. These results indicate the importance of belowground biomass when assessing seagrass recovery and suggest that the appropriate metric to assess seagrass recovery should address belowground biomass as well as aboveground biomass in order to evaluate the full recovery of ecological services and functions performed by seagrasses. We point out regional differences in species composition and species shifts following severe disturbance events and discuss

  16. Seagrass distribution and abundance in Eastern Gulf of Mexico coastal waters

    Science.gov (United States)

    Iverson, Richard L.; Bittaker, Henry F.

    1986-05-01

    The marine angiosperms Thalassia testudinum, Syringodium filiforme, and Halodule wrightii form two of the largest reported seagrass beds along the northwest and southern coasts of Florida where they cover about 3000 square km in the Big Bend area and about 5500 square km in Florida Bay, respectively. Most of the leaf biomass in the Big Bend area and outer Florida Bay was composed of Thalassia testudinum and Syringodium filiforme which were distributed throughout the beds but which were more abundant in shallow depths. A short-leaved form of Halodule wrightii grew in monotypic stands in shallow water near the inner edges of the beds, while Halophila decipiens and a longer-leaved variety of H. wrightii grew scattered throughout the beds, in monotypic stands near the outer edges of the beds, and in deeper water outside the beds. Halophila engelmanni was observed scattered at various depths throughout the seagrass beds and in monospecific patches in deep water outside the northern bed. Ruppia maritima grew primarily in brackish water around river mouths. The cross-shelf limits of the two major seagrass beds are controlled nearshore by increased water turbidity and lower salinity around river mouths and off-shore by light penetration to depths which receive 10% or more of sea surface photosynthetically active radiation. Seagrasses form large beds only along low energy reaches of the coast. The Florida Bay seagrass bed contained about twice the short-shoot density of both Thalassia testudinum and Syringodium filiforme, for data averaged over all depths, and about four times the average short-shoot density of both species in shallow water compared with the Big Bend seagrass bed. The differences in average seagrass abundance between Florida Bay and the Big Bend area may be a consequence of the effects of greater seasonal solar radiation and water temperature fluctuations experienced by plants in the northern bed, which lies at the northern distribution limit for American

  17. Genetic variability and nitrogenase activity of cyanobacterial communities associated with tropical seagrass meadows (western Indian Ocean)

    OpenAIRE

    Hamisi, Mariam

    2010-01-01

    Tropical seagrass ecosystems are highly productive and important for sustaining marine life and associated coastal societies. In this study, the diversity and role of nitrogen-fixing cyanobacteria associated with five common seagrass genera in coastal regions of the western Indian Ocean (WIO; Tanzania) were examined, as well as the impact of anthropogenic activities. Cyanobacteria were characterized morphologically and genetically (16S rRNA and nifH gene phylogeny), as were diel variations in...

  18. Brevetoxin persistence in sediments and seagrass epiphytes of east Florida coastal waters.

    Science.gov (United States)

    Hitchcock, Gary L; Fourqurean, James W; Drake, Jeana L; Mead, Ralph N; Heil, Cynthia A

    2012-01-01

    A bloom of Karenia brevis Davis developed in September 2007 near Jacksonville, Florida and subsequently progressed south through east Florida coastal waters and the Atlantic Intracoastal Waterway (ICW). Maximum cell abundances exceeded 10(6) cells L(-1) through October in the northern ICW between Jacksonville and the Indian River Lagoon. The bloom progressed further south during November, and terminated in December 2007 at densities of 10(4) cells L(-1) in the ICW south of Jupiter Inlet, Florida. Brevetoxins were subsequently sampled in sediments and seagrass epiphytes in July and August 2008 in the ICW. Sediment brevetoxins occurred at concentrations of 11-15 ng PbTx-3 equivalents (g dry wt sediment)(-1) in three of five basins in the northern ICW during summer 2008. Seagrass beds occur south of the Mosquito Lagoon in the ICW. Brevetoxins were detected in six of the nine seagrass beds sampled between the Mosquito Lagoon and Jupiter Inlet at concentrations of 6-18 ng (g dry wt epiphytes)(-1). The highest brevetoxins concentrations were found in sediments near Patrick Air Force Base at 89 ng (g dry wt sediment)(-1). In general, brevetoxins occurred in either seagrass epiphytes or sediments. Blades of the resident seagrass species have a maximum life span of less than six months, so it is postulated that brevetoxins could be transferred between epibenthic communities of individual blades in seagrass beds. The occurrence of brevetoxins in east Florida coast sediments and seagrass epiphytes up to eight months after bloom termination supports observations from the Florida west coast that brevetoxins can persist in marine ecosystems in the absence of sustained blooms. Furthermore, our observations show that brevetoxins can persist in sediments where seagrass communities are absent.

  19. Food-web structure of seagrass communities across different spatial scales and human impacts.

    Science.gov (United States)

    Coll, Marta; Schmidt, Allison; Romanuk, Tamara; Lotze, Heike K

    2011-01-01

    Seagrass beds provide important habitat for a wide range of marine species but are threatened by multiple human impacts in coastal waters. Although seagrass communities have been well-studied in the field, a quantification of their food-web structure and functioning, and how these change across space and human impacts has been lacking. Motivated by extensive field surveys and literature information, we analyzed the structural features of food webs associated with Zostera marina across 16 study sites in 3 provinces in Atlantic Canada. Our goals were to (i) quantify differences in food-web structure across local and regional scales and human impacts, (ii) assess the robustness of seagrass webs to simulated species loss, and (iii) compare food-web structure in temperate Atlantic seagrass beds with those of other aquatic ecosystems. We constructed individual food webs for each study site and cumulative webs for each province and the entire region based on presence/absence of species, and calculated 16 structural properties for each web. Our results indicate that food-web structure was similar among low impact sites across regions. With increasing human impacts associated with eutrophication, however, food-web structure show evidence of degradation as indicated by fewer trophic groups, lower maximum trophic level of the highest top predator, fewer trophic links connecting top to basal species, higher fractions of herbivores and intermediate consumers, and higher number of prey per species. These structural changes translate into functional changes with impacted sites being less robust to simulated species loss. Temperate Atlantic seagrass webs are similar to a tropical seagrass web, yet differed from other aquatic webs, suggesting consistent food-web characteristics across seagrass ecosystems in different regions. Our study illustrates that food-web structure and functioning of seagrass habitats change with human impacts and that the spatial scale of food-web analysis

  20. The Power of Three: Coral Reefs, Seagrasses and Mangroves Protect Coastal Regions and Increase Their Resilience.

    Science.gov (United States)

    Guannel, Greg; Arkema, Katie; Ruggiero, Peter; Verutes, Gregory

    2016-01-01

    Natural habitats have the ability to protect coastal communities against the impacts of waves and storms, yet it is unclear how different habitats complement each other to reduce those impacts. Here, we investigate the individual and combined coastal protection services supplied by live corals on reefs, seagrass meadows, and mangrove forests during both non-storm and storm conditions, and under present and future sea-level conditions. Using idealized profiles of fringing and barrier reefs, we quantify the services supplied by these habitats using various metrics of inundation and erosion. We find that, together, live corals, seagrasses, and mangroves supply more protection services than any individual habitat or any combination of two habitats. Specifically, we find that, while mangroves are the most effective at protecting the coast under non-storm and storm conditions, live corals and seagrasses also moderate the impact of waves and storms, thereby further reducing the vulnerability of coastal regions. Also, in addition to structural differences, the amount of service supplied by habitats in our analysis is highly dependent on the geomorphic setting, habitat location and forcing conditions: live corals in the fringing reef profile supply more protection services than seagrasses; seagrasses in the barrier reef profile supply more protection services than live corals; and seagrasses, in our simulations, can even compensate for the long-term degradation of the barrier reef. Results of this study demonstrate the importance of taking integrated and place-based approaches when quantifying and managing for the coastal protection services supplied by ecosystems.

  1. Community metabolism in shallow coral reef and seagrass ecosystems, lower Florida Keys

    Science.gov (United States)

    Turk, Daniela; Yates, Kimberly K.; Vega-Rodriguez, Maria; Toro-Farmer, Gerardo; L'Esperance, Chris; Melo, Nelson; Ramsewak, Deanesch; Estrada, S. Cerdeira; Muller-Karger, Frank E.; Herwitz, Stan R.; McGillis, Wade

    2016-01-01

    Diurnal variation of net community production (NEP) and net community calcification (NEC) were measured in coral reef and seagrass biomes during October 2012 in the lower Florida Keys using a mesocosm enclosure and the oxygen gradient flux technique. Seagrass and coral reef sites showed diurnal variations of NEP and NEC, with positive values at near-seafloor light levels >100–300 µEinstein m-2 s-1. During daylight hours, we detected an average NEP of 12.3 and 8.6 mmol O2 m-2 h-1 at the seagrass and coral reef site, respectively. At night, NEP at the seagrass site was relatively constant, while on the coral reef, net respiration was highest immediately after dusk and decreased during the rest of the night. At the seagrass site, NEC values ranged from 0.20 g CaCO3 m-2 h-1 during daylight to -0.15 g CaCO3 m-2 h-1 at night, and from 0.17 to -0.10 g CaCO3 m-2 h-1 at the coral reef site. There were no significant differences in pH and aragonite saturation states (Ωar) between the seagrass and coral reef sites. Decrease in light levels during thunderstorms significantly decreased NEP, transforming the system from net autotrophic to net heterotrophic.

  2. Mangroves as a major source of soil carbon storage in adjacent seagrass meadows

    Science.gov (United States)

    Chen, Guangcheng; Azkab, Muhammad Husni; Chmura, Gail L.; Chen, Shunyang; Sastrosuwondo, Pramudji; Ma, Zhiyuan; Dharmawan, I. Wayan Eka; Yin, Xijie; Chen, Bin

    2017-01-01

    Mangrove forests have the potential to export carbon to adjacent ecosystems but whether mangrove-derived organic carbon (OC) would enhance the soil OC storage in seagrass meadows adjacent to mangroves is unclear. In this study we examine the potential for the contribution of mangrove OC to seagrass soils on the coast of North Sulawesi, Indonesia. We found that seagrass meadows adjacent to mangroves had significantly higher soil OC concentrations, soil OC with lower δ 13C, and lower bulk density than those at the non-mangrove adjacent meadows. Soil OC storage to 30 cm depth ranged from 3.21 to 6.82 kg C m−2, and was also significantly higher at the mangrove adjacent meadows than those non-adjacent meadows. δ13C analyses revealed that mangrove OC contributed 34 to 83% to soil OC at the mangrove adjacent meadows. The δ13C value of seagrass plants was also different between the seagrasses adjacent to mangroves and those which were not, with lower values measured at the seagrasses adjacent to mangroves. Moreover, we found significant spatial variation in both soil OC concentration and storage, with values decreasing toward sea, and the contribution of mangrove-derived carbon also reduced with distance from the forest. PMID:28186151

  3. Seagrass resource assessment using remote sensing methods in St. Joseph Sound and Clearwater Harbor, Florida, USA.

    Science.gov (United States)

    Meyer, Cynthia A; Pu, Ruiliang

    2012-01-01

    In the event of a natural or anthropogenic disturbance, environmental resource managers require a reliable tool to quickly assess the spatial extent of potential damage to the seagrass resource. The temporal availability of the Landsat 5 Thematic Mapper (TM) imagery provided a suitable option to detect and assess damage of the submerged aquatic vegetation (SAV). This study examined Landsat TM imagery classification techniques to create two-class (SAV presence/absence) and three-class (SAV estimated coverage) SAV maps of the seagrass resource. The Mahalanobis Distance method achieved the highest overall accuracy (86%) and validation accuracy (68%) for delineating the seagrass resource (two-class SAV map). The Maximum Likelihood method achieved the highest overall accuracy (74%) and validation accuracy (70%) for delineating the seagrass resource three-class SAV map. The Landsat 5 TM imagery classification provided a seagrass resource map product with similar accuracy to the aerial photointerpretation maps (validation accuracy 71%). The results support the application of remote sensing methods to analyze the spatial extent of the seagrass resource.

  4. Familial Mediterranean Fever

    Science.gov (United States)

    ... don't use genetic tests as the sole method of diagnosing familial Mediterranean fever. There's no cure ... may be options, though these treatments are considered experimental. Other medications include rilonacept (Arcalyst) and anakinra (Kineret). ...

  5. Global analysis of seagrass restoration: the importance of large-scale planting

    KAUST Repository

    van Katwijk, Marieke M.

    2015-10-28

    In coastal and estuarine systems, foundation species like seagrasses, mangroves, saltmarshes or corals provide important ecosystem services. Seagrasses are globally declining and their reintroduction has been shown to restore ecosystem functions. However, seagrass restoration is often challenging, given the dynamic and stressful environment that seagrasses often grow in. From our world-wide meta-analysis of seagrass restoration trials (1786 trials), we describe general features and best practice for seagrass restoration. We confirm that removal of threats is important prior to replanting. Reduced water quality (mainly eutrophication), and construction activities led to poorer restoration success than, for instance, dredging, local direct impact and natural causes. Proximity to and recovery of donor beds were positively correlated with trial performance. Planting techniques can influence restoration success. The meta-analysis shows that both trial survival and seagrass population growth rate in trials that survived are positively affected by the number of plants or seeds initially transplanted. This relationship between restoration scale and restoration success was not related to trial characteristics of the initial restoration. The majority of the seagrass restoration trials have been very small, which may explain the low overall trial survival rate (i.e. estimated 37%). Successful regrowth of the foundation seagrass species appears to require crossing a minimum threshold of reintroduced individuals. Our study provides the first global field evidence for the requirement of a critical mass for recovery, which may also hold for other foundation species showing strong positive feedback to a dynamic environment. Synthesis and applications. For effective restoration of seagrass foundation species in its typically dynamic, stressful environment, introduction of large numbers is seen to be beneficial and probably serves two purposes. First, a large-scale planting

  6. Seasonal variations in seagrass percentage cover and biomass at Koh Tha Rai, Nakhon Si Thammarat Province, Gulf of Thailand

    Directory of Open Access Journals (Sweden)

    Anchana Prathep

    2010-10-01

    Full Text Available Seasonal variations in seagrass percentage cover and biomass at Koh Tha Rai, Nakhon Si Thammarat Province, Gulf ofThailand, were investigated between July 2006 - July 2008 using SeagrassNet protocol. The SeagrassNet protocol is astandard method for monitoring seagrass worldwide, and Koh Tha Rai is among the first few places using such protocol inThailand. The standard protocol such as SeagrassNet allows comparisons of findings among various sites worldwide. Fivespecies of seagrass found at Koh Tha Rai : Enhalus acoroides (L.f. Royle, Cymodocea rotundata Asch. & Schweinf.,Thalassia hemprichii (Ehrenb.Asch., Halophila ovalis (R.Br. Hook.f. and Halodule uninervis (Forssk. Asch. E. acoroidescovered the largest area, while C. rotundata covered only a small area. Most seagrass showed seasonal variations both inpercentage cover and biomass. There were also variations in above and below ground biomass as well as in the sediment.There was a decline of seagrass with increasing of sedimentation in a sheltered site. This study provides a systematic monitoringof seagrass in Thailand, which is still limited.

  7. Declines of seagrasses in a tropical harbour, North Queensland, Australia, are not the result of a single event

    Indian Academy of Sciences (India)

    Skye McKenna; Jessie Jarvis; Tonia Sankey; Carissa Reason; Robert Coles; Michael Rasheed

    2015-06-01

    A recent paper inferred that all seagrass in Cairns Harbour, tropical north-eastern Australia, had undergone ‘complete and catastrophic loss’ as a result of tropical cyclone Yasi in 2011. While we agree with the concern expressed, we would like to correct the suggestion that the declines were the result of a single climatic event and that all seagrass in Cairns Harbour were lost. Recent survey data and trend analysis from an on-ground monitoring program show that seagrasses in Cairns Harbour do remain, albeit at low levels, and the decline in seagrasses occurred over several years with cyclone Yasi having little additional impact. We have conducted annual on-ground surveys of seagrass distribution and the above-ground meadow biomass in Cairns Harbour and Trinity Inlet since 2001. This has shown a declining trend in biomass since a peak in 2004 and in area since it peaked in 2007. In 2012, seagrass area and above-ground biomass were significantly below the long-term (12 year) average but seagrass was still present. Declines were associated with regional impacts on coastal seagrasses from multiple years of above-average rainfall and severe storm and cyclone activity, similar to other nearby seagrass areas, and not as a result of a single event.

  8. Declines of seagrasses in a tropical harbour, North Queensland, Australia, are not the result of a single event.

    Science.gov (United States)

    McKENNA, Skye; Jarvis, Jessie; Sankey, Tonia; Reason, Carissa; Coles, Robert; Rasheed, Michael

    2015-06-01

    A recent paper inferred that all seagrass in Cairns Harbour, tropical north-eastern Australia, had undergone 'complete and catastrophic loss' as a result of tropical cyclone Yasi in 2011. While we agree with the concern expressed, we would like to correct the suggestion that the declines were the result of a single climatic event and that all seagrass in Cairns Harbour were lost. Recent survey data and trend analysis from an on-ground monitoring program show that seagrasses in Cairns Harbour do remain, albeit at low levels, and the decline in seagrasses occurred over several years with cyclone Yasi having little additional impact. We have conducted annual on-ground surveys of seagrass distribution and the above-ground meadow biomass in Cairns Harbour and Trinity Inlet since 2001. This has shown a declining trend in biomass since a peak in 2004 and in area since it peaked in 2007. In 2012, seagrass area and above-ground biomass were significantly below the long-term (12 year) average but seagrass was still present. Declines were associated with regional impacts on coastal seagrasses from multiple years of above-average rainfall and severe storm and cyclone activity, similar to other nearby seagrass areas, and not as a result of a single event.

  9. Influence of New Zealand cockles (Austrovenus stutchburyi) on primary productivity in sandflat-seagrass (Zostera muelleri) ecotones

    Science.gov (United States)

    Lohrer, Andrew M.; Townsend, Michael; Hailes, Sarah F.; Rodil, Iván F.; Cartner, Katie; Pratt, Daniel R.; Hewitt, Judi E.

    2016-11-01

    New Zealand cockles (Austrovenus stutchburyi) are ecologically important, intertidal bivalves that have been shown to influence nutrient cycles and the productivity of microphytobenthos on sandflats. Here, we investigated the potential for cockles to impact the productivity of seagrass, Zostera muelleri, and examined interactions between these habitat-defining species where they co-occur. We sampled bivalve densities and sizes, sediment properties, and seagrass shoot densities across the boundaries of two seagrass patches on an intertidal sandflat in northern New Zealand, and measured dissolved oxygen and nutrient fluxes in light and dark benthic incubation chambers in conjunction with a 0-97% gradient in seagrass cover. Although gross primary production (GPP, μmol O2 m-2 h-1) increased predictably with the cover of live seagrass, the density of cockles and sediment properties also contributed directly and indirectly. Seagrass cover was positively correlated with cockle density (ranging from 225 to 1350 individuals per m2), sediment mud percentage (0.5-9.5%), and organic matter content (0.5-2.2%), all of which can affect the efflux of ammonium (readily utilisable inorganic nitrogen) from sediments. Moreover, the cover of green seagrass blades plateaued (never exceeded 70%) in the areas of highest total seagrass cover, adding complexity to cockle-seagrass interactions and contributing to a unimodal cockle-GPP relationship.

  10. Mapping spatial resources with GPS animal telemetry: foraging manatees locate seagrass beds in the Ten Thousand Islands, Florida, USA

    Science.gov (United States)

    Slone, Daniel H.; Reid, James P.; Kenworthy, W. Judson

    2013-01-01

    Turbid water conditions make the delineation and characterization of benthic habitats difficult by traditional in situ and remote sensing methods. Here, we develop and validate modeling and sampling methodology for detecting and characterizing seagrass beds by analyzing GPS telemetry records from radio-tagged manatees. Between October 2002 and October 2005, 14 manatees were tracked in the Ten Thousand Islands (TTI) in southwest Florida (USA) using Global Positioning System (GPS) tags. High density manatee use areas were found to occur off each island facing the open, nearshore waters of the Gulf of Mexico. We implemented a spatially stratified random sampling plan and used a camera-based sampling technique to observe and record bottom observations of seagrass and macroalgae presence and abundance. Five species of seagrass were identified in our study area: Halodule wrightii, Thalassia testudinum, Syringodium filiforme, Halophila engelmannii, and Halophila decipiens. A Bayesian model was developed to choose and parameterize a spatial process function that would describe the observed patterns of seagrass and macroalgae. The seagrasses were found in depths <2 m and in the higher manatee use strata, whereas macroalgae was found at moderate densities at all sampled depths and manatee use strata. The manatee spatial data showed a strong association with seagrass beds, a relationship that increased seagrass sampling efficiency. Our camera-based field sampling proved to be effective for assessing seagrass density and spatial coverage under turbid water conditions, and would be an effective monitoring tool to detect changes in seagrass beds.

  11. Impact of drilling fluids on seagrasses: an experimental community approach

    Energy Technology Data Exchange (ETDEWEB)

    Morton, R.D.; Duke, T.W.; Macauley, J.M.; Clark, J.R.; Price, W.A.

    1985-06-01

    Effects of a used drilling fluid on an experimental seagrass community (Thalassia testudinum) were measured by exposing the community to the suspended particulate phase (SPP) in laboratory microcosms. Structure of the macroinvertebrate assemblage, growth and chlorophyll content of grass and associated epiphytes, and rates of decomposition as indicated by weight loss of grass leaves in treated and untreated microcosms were compared. There were statistically significant differences in community structure and function among untreated microcosms and those receiving the clay and drilling fluid. For example, drilling fluid and clay caused a significant loss in the number of the ten most numerically abundant (dominant) macroinvertebrates, and drilling fluid decreased the rate at which Thalassia leaves decomposed.

  12. 海草及海草场生态系统研究进展%Research progress on seagrass and seagrass ecosystems

    Institute of Scientific and Technical Information of China (English)

    王锁民; 崔彦农; 刘金祥; 夏曾润

    2016-01-01

    Seagrasses are underwater flowering plants widely distributed in shallow seas often forming vast seagrass based ecosystems.Seagrass ecosystems are one of the most productive aquatic ecosystems in the world and a globally significant carbon store due to the unique features of seagrass which allow efficient photosynthe-sis underwater.Seagrass ecosystems provide a range of important ecological service functions and they act as biological sentinels used to assess the health of coastal ecosystems.Recently,rapidly decreases in the number of individual seagrass species and the number of seagrass meadows caused by the multiple stressors including natural factors and human effects had led to a situation where 14% of all seagrass species are at risk of extinc-tion and about one-third seagrass meadows have disappeared worldwide.In response to this decline,there has been a significant increase in the number of marine protected areas during the last decade,including seagrass monitoring and restoration projects which aim to prevent the extinction of individual seagrass species and pre-vent the large scale loss of seagrass meadows throughout the world.Current restoration projects involve habitat improvement through reduction in eutrophication or alteration of hydrology and the use of artificial transplanta-tions which can be an effective method of restoration.Seagrass monitoring and restoration projects have a-chieved some positive preliminary results and provide useful guidelines for seagrass restoration.However there are challenges including limited theoretical approaches,appropriate technology,and uncertainty of outcome from seagrass transplantation and restoration projects and cost.This paper reviews the research on seagrasses and seagrass ecosystems globally,clarifies their importance to the biosphere and the risks to their survival to raise the awareness of the public,government and international agencies of the need to protect seagrass ecosys-tems.%海草是分布于全

  13. Biomechanical factors contributing to self-organization in seagrass landscapes

    Science.gov (United States)

    Fonseca, M.S.; Koehl, M.A.R.; Kopp, B.S.

    2007-01-01

    Field observations have revealed that when water flow is consistently from one direction, seagrass shoots align in rows perpendicular to the primary axis of flow direction. In this study, live Zostera marina shoots were arranged either randomly or in rows perpendicular to the flow direction and tested in a seawater flume under unidirectional flow and waves to determine if shoot arrangement: a) influenced flow-induced force on individual shoots, b) differentially altered water flow through the canopy, and c) influenced light interception by the canopy. In addition, blade breaking strength was compared with flow-induced force to determine if changes in shoot arrangement might reduce the potential for damage to shoots. Under unidirectional flow, both current velocity in the canopy and force on shoots were significantly decreased when shoots were arranged in rows as compared to randomly. However, force on shoots was nearly constant with downstream distance, arising from the trade-off of shoot bending and in-canopy flow reduction. The coefficient of drag was higher for randomly-arranged shoots at low velocities (< 30 cm s- 1) but converged rapidly among the two shoot arrangements at higher velocities. Shoots arranged in rows tended to intercept slightly more light than those arranged randomly. Effects of shoot arrangement under waves were less clear, potentially because we did not achieve the proper plant size?row spacing ratio. At this point, we may only suggest that water motion, as opposed to light capture, is the dominant physical mechanism responsible for these shoot arrangements. Following a computation of the Environmental Stress Factor, we concluded that even photosynthetically active blades may be damaged or broken under frequently encountered storm conditions, irrespective of shoot arrangement. We hypothesize that when flow is generally from one direction, seagrass bed patterns over multiple scales of consideration may arise as a cumulative effect of

  14. Spatial variation in reproductive effort of a southern Australian seagrass.

    Science.gov (United States)

    Smith, Timothy M; York, Paul H; Macreadie, Peter I; Keough, Michael J; Ross, D Jeff; Sherman, Craig D H

    2016-09-01

    In marine environments characterised by habitat-forming plants, the relative allocation of resources into vegetative growth and flowering is an important indicator of plant condition and hence ecosystem health. In addition, the production and abundance of seeds can give clues to local resilience. Flowering density, seed bank, biomass and epiphyte levels were recorded for the temperate seagrass Zostera nigricaulis in Port Phillip Bay, south east Australia at 14 sites chosen to represent several regions with different physicochemical conditions. Strong regional differences were found within the large bay. Spathe and seed density were very low in the north of the bay (3 sites), low in the centre of the bay (2 sites) intermediate in the Outer Geelong Arm (2 sites), high in Swan Bay (2 sites) and very high in the Inner Geelong Arm (3 sites). In the south (2 sites) seed density was low and spathe density was high. These regional patterns were largely consistent for the 5 sites sampled over the three year period. Timing of flowering was consistent across sites, occurring from August until December with peak production in October, except during the third year of monitoring when overall densities were lower and peaked in November. Seagrass biomass, epiphyte load, canopy height and stem density showed few consistent spatial and temporal patterns. Variation in spathe and seed density and morphology across Port Phillip Bay reflects varying environmental conditions and suggests that northern sites may be restricted in their ability to recover from disturbance through sexual reproduction. In contrast, sites in the west and south of the bay have greater potential to recover from disturbances due to a larger seed bank and these sites could act as source populations for sites where seed production is low.

  15. Ecophysiological Plasticity and Bacteriome Shift in the Seagrass Halophila stipulacea along a Depth Gradient in the Northern Red Sea.

    Science.gov (United States)

    Rotini, Alice; Mejia, Astrid Y; Costa, Rodrigo; Migliore, Luciana; Winters, Gidon

    2016-01-01

    Halophila stipulacea is a small tropical seagrass species. It is the dominant seagrass species in the Gulf of Aqaba (GoA; northern Red Sea), where it grows in both shallow and deep environments (1-50 m depth). Native to the Red Sea, Persian Gulf, and Indian Ocean, this species has invaded the Mediterranean and has recently established itself in the Caribbean Sea. Due to its invasive nature, there is growing interest to understand this species' capacity to adapt to new conditions, which might be attributed to its ability to thrive in a broad range of ecological niches. In this study, a multidisciplinary approach was used to depict variations in morphology, biochemistry (pigment and phenol content) and epiphytic bacterial communities along a depth gradient (4-28 m) in the GoA. Along this gradient, H. stipulacea increased leaf area and pigment contents (Chlorophyll a and b, total Carotenoids), while total phenol contents were mostly uniform. H. stipulacea displayed a well conserved core bacteriome, as assessed by 454-pyrosequencing of 16S rRNA gene reads amplified from metagenomic DNA. The core bacteriome aboveground (leaves) and belowground (roots and rhizomes), was composed of more than 100 Operational Taxonomic Units (OTUs) representing 63 and 52% of the total community in each plant compartment, respectively, with a high incidence of the classes Alphaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria across all depths. Above and belowground communities were different and showed higher within-depth variability at the intermediate depths (9 and 18 m) than at the edges. Plant parts showed a clear influence in shaping the communities while depth showed a greater influence on the belowground communities. Overall, results highlighted a different ecological status of H. stipulacea at the edges of the gradient (4-28 m), where plants showed not only marked differences in morphology and biochemistry, but also the most distinct associated bacterial consortium. We

  16. Ecophysiological Plasticity and Bacteriome Shift in the Seagrass Halophila stipulacea along a Depth Gradient in the Northern Red Sea

    Science.gov (United States)

    Rotini, Alice; Mejia, Astrid Y.; Costa, Rodrigo; Migliore, Luciana; Winters, Gidon

    2017-01-01

    Halophila stipulacea is a small tropical seagrass species. It is the dominant seagrass species in the Gulf of Aqaba (GoA; northern Red Sea), where it grows in both shallow and deep environments (1–50 m depth). Native to the Red Sea, Persian Gulf, and Indian Ocean, this species has invaded the Mediterranean and has recently established itself in the Caribbean Sea. Due to its invasive nature, there is growing interest to understand this species’ capacity to adapt to new conditions, which might be attributed to its ability to thrive in a broad range of ecological niches. In this study, a multidisciplinary approach was used to depict variations in morphology, biochemistry (pigment and phenol content) and epiphytic bacterial communities along a depth gradient (4–28 m) in the GoA. Along this gradient, H. stipulacea increased leaf area and pigment contents (Chlorophyll a and b, total Carotenoids), while total phenol contents were mostly uniform. H. stipulacea displayed a well conserved core bacteriome, as assessed by 454-pyrosequencing of 16S rRNA gene reads amplified from metagenomic DNA. The core bacteriome aboveground (leaves) and belowground (roots and rhizomes), was composed of more than 100 Operational Taxonomic Units (OTUs) representing 63 and 52% of the total community in each plant compartment, respectively, with a high incidence of the classes Alphaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria across all depths. Above and belowground communities were different and showed higher within-depth variability at the intermediate depths (9 and 18 m) than at the edges. Plant parts showed a clear influence in shaping the communities while depth showed a greater influence on the belowground communities. Overall, results highlighted a different ecological status of H. stipulacea at the edges of the gradient (4–28 m), where plants showed not only marked differences in morphology and biochemistry, but also the most distinct associated bacterial

  17. A GIS Analysis of Seagrass Resources and Condition Within Padre Island National Seashore, Texas

    Science.gov (United States)

    Onuf, Christopher P.; Ingold, Jaimie J.

    2007-01-01

    A survey of the seagrass resources of Padre Island National Seashore was conducted in fall 2002 and 2003, with additional sampling through 2006, to resolve distribution questions. Location coordinates were recorded to thousandths of minutes of latitude and longitude and converted to decimal degrees (minus decimal degrees for longitude) for import into ArcView (Environmental Systems Research Institute, Inc.). The seagrass core frequency data were developed as a theme in ArcView and overlaid on digital orthophoto quarter quadrangles of the U.S. Geological Survey to show sample depth with respect to mean sea level and frequency of occurrence of seagrass for five samples collected from every station sampled. These data were used to draw boundaries of area submerged at mean sea level and seagrass meadow in relation to the boundary of Padre Island National Seashore. Frequency of seagrass occurrence, mean plant height, shoot density, plant height multiplied by shoot density, live biomass, and dead biomass on a 1' latitude by 0.25' longitude grid were collected, and their distribution was plotted in space and according to depth. A User Guide for displaying data in ArcView is included at the end of this report. Seagrasses covered almost two-thirds of the regularly flooded part of Laguna Madre within the borders of Padre Island National Seashore. Comparisons with earlier surveys showed that substantial areas of seagrass cover had been lost in deep water between 1988 and 1998 as a result of a persistent phytoplankton bloom, and little recovery has occurred since. Maximum depth of seagrass occurrence responded to changes in water clarity. In contrast, much of the cover at shallow to intermediate depths lost at the south end of the study area between 1988 and 1998 was replaced by 2003. The seven stations with greatest plant height were located in this area of recent recolonization. Continuity of cover as measured by frequency of occurrence was high except near the edge of

  18. [Hurricane Paloma's effects on seagrasses along Jardines de la Reina Archipelago, Cuba].

    Science.gov (United States)

    Guimarais, Mayrene; Zúñiga, Adán; Pina, Fabián; Matos, Felipe

    2013-09-01

    Seagrasses are one of the most important coastal ecosystems since they promote organic matter flow, nutrient cycling, food availability and refuge. Until now, reports on damages caused by storms and hurricanes on seagrass beds are uncommon and highly variable. The seagrass meadows of the East end of Jardines de la Reina archipelago were surveyed from Nov. 29th to Dec. 5th of 2008, in order to determinate the effects from the passing of Hurricane Paloma: a category three storm on the Saffir-Simpsom scale. A rapid field assessment of the affected areas was carried out using the manta tow technique. In six sites, seagrass was quantitatively evaluated using a 15cm diameter core (four sampling units per site) and shoot density was calculated. Remote sensing techniques were used to estimate seagrass cover. To estimate the percentage of affected areas, a Region of Interest (ROI) was first created over a Landsat image. The percentage of seagrass affected within the ROI was estimated through direct georeferentiation of the contours of the damaged area and with a comparison to the total seagrass extension. To find possible explanations for damages, a false colour image was created using the near infrared band, to highlight the differences between emerged and submerged zones. The direction of winds was estimated using ArcGis 9.2 creating circular buffers, from the centre of the hurricane and generating lines tangent to the buffers. Seagrass in the region was dominated by the angiosperm Thalassia testudinum. Regional mean density was 1 321 +/- 721 shoots/m2, a value regarded as high for the Caribbean area. Seagrass meadows were partly affected by sediment accumulation on the shoots of T. testudinum and uprooting rhizomes. The 7.6 km2 disturbed area represented 1% of the total seagrass area. Other sites, closer to the centre of the hurricane, did not show any damages on the marine vegetation. The keys location with respect to the hurricane track was the most likely cause of the

  19. Trophic ecology of the seagrass-inhabiting footballer demoiselle Chrysiptera annulata (Peters, 1855); comparison with three other reef-associated damselfishes

    OpenAIRE

    Lepoint, G.; Michel, L.; Parmentier, E; Frédérich, B.

    2016-01-01

    Many damselfishes (Pomacentridae) are herbivorous or omnivorous with an important contribution from different kinds of algae in their diet. They display different levels of territoriality and farming behavior, from almost non territorial to monoculture farmers. In addition, a few species inhabit seagrass meadows but, presently, none can be considered as seagrass-eating specialists. The footballer demoiselle, Chrysiptera annulata, is found in the seagrass meadows on the reef flat of the Great ...

  20. Trophic ecology of the seagrass-inhabiting footballer demoiselle Chrysiptera annulata (Peters, 1855); comparison with three other reef-associated damselfishes

    OpenAIRE

    Lepoint, Gilles; Michel, Loïc; Parmentier, Eric; Frederich, Bruno

    2016-01-01

    Many damselfishes (Pomacentridae) are herbivorous or omnivorous with an important contribution of different kinds of algae in their diet. They display different levels of territoriality and farming behavior, from almost non territorial to monoculture farmers. In addition, few species inhabit seagrass meadows but, presently, none can be considered as seagrass-eating specialists. The footballer demoiselle, Chrysiptera annulata, is found in the seagrass meadows on the reef flat of the Great Reef...

  1. A Global Assessment of the Chemical Recalcitrance of Seagrass Tissues: Implications for Long-Term Carbon Sequestration

    Directory of Open Access Journals (Sweden)

    Stacey M. Trevathan-Tackett

    2017-06-01

    Full Text Available Seagrass ecosystems have recently been identified for their role in climate change mitigation due to their globally-significant carbon sinks; yet, the capacity of seagrasses to sequester carbon has been shown to vary greatly among seagrass ecosystems. The recalcitrant nature of seagrass tissues, or the resistance to degradation back into carbon dioxide, is one aspect thought to influence sediment carbon stocks. In this study, a global survey investigated how the macromolecular chemistry of seagrass leaves, sheaths/stems, rhizomes and roots varied across 23 species from 16 countries. The goal was to understand how this seagrass chemistry might influence the capacity of seagrasses to contribute to sediment carbon stocks. Three non-destructive analytical chemical analyses were used to investigate seagrass chemistry: thermogravimetric analysis (TGA and solid state 13C-NMR and infrared spectroscopy. A strong latitudinal influence on carbon quality was found, whereby temperate seagrasses contained 5% relatively more labile carbon, and tropical seagrasses contained 3% relatively more refractory carbon. Sheath/stem tissues significantly varied across taxa, with larger morphologies typically containing more refractory carbon than smaller morphologies. Rhizomes were characterized by a higher proportion of labile carbon (16% of total organic matter compared to 8–10% in other tissues; however, high rhizome biomass production and slower remineralization in anoxic sediments will likely enhance these below-ground tissues' contributions to long-term carbon stocks. Our study provides a standardized and global dataset on seagrass carbon quality across tissue types, taxa and geography that can be incorporated in carbon sequestration and storage models as well as ecosystem valuation and management strategies.

  2. Application of Landsat images to seagrass areal cover change analysis for Lawas, Terengganu and Kelantan of Malaysia

    Science.gov (United States)

    Hossain, M. S.; Bujang, J. S.; Zakaria, M. H.; Hashim, M.

    2015-11-01

    Seagrass mapping and monitoring using remote sensing has been established using various imageries and mapping methods, ranging from complex optical modeling to manual interpretations. Few attempts have been made to find relations between spatiotemporal changes within seagrass habitats and their surrounding environment in the mapping efforts. In this study, issues of spatiotemporal changes in seagrass habitat including water quality, and causes and processes of seagrass degradation were addressed through assessing the ability of integrated manual enhancement and seed pixel growing techniques on multi-date Landsat images for mapping and monitoring seagrass resources. This integrated approach was tested on a total of forty-nine Landsat 5, 7 and 8 images of the seagrass meadow spatial distribution and cover change analysis for Punag-Sari estuary (Lawas), Pengkalan Nangka (Kelantan) lagoon, and Paka (Terengganu) lagoon of Malaysia. The resulted maps demonstrated the ability of Landsat images for producing spatially extensive maps and allowed quantitative estimation of seagrass coverage, accretion/erosion, and describe changes in noticeable areas. The findings indicated that a noticeable loss of seagrass habitats at varying magnitude occurred between 2000 and 2014 for Punang-Sari, between 1998 and 2014 for Pegkalan Nangka, and between 1988 and 2014 for Paka. The natural event mainly sand shifting was the main cause of seagrass habitat loss for Punang-Sari Lawas. Coastline change was identified as the most significant factor that caused seagrass spatial cover loss of the Pengkalan Nangka lagoon. The seagrass meadows of Pengkalan Nangka and Paka were greatly affected by natural events including floods, and local human-induced interferences such as dredging, and sand mining. The mapping approach and the map products presented in this paper will be a useful information source for the coastal management agencies involved in monitoring and management programs.

  3. Seasonality in vegetation biometrics and its effects on sediment characteristics and meiofauna in Baltic seagrass meadows

    Science.gov (United States)

    Jankowska, Emilia; Włodarska-Kowalczuk, Maria; Kotwicki, Lech; Balazy, Piotr; Kuliński, Karol

    2014-02-01

    Seagrass meadows can act as ecosystem engineers, i.e., organisms that modify the availability of resources to other organisms. However, their possible positive impacts depend on the characteristics of the vegetation, and these can vary strongly seasonally. This study assesses seasonal variability in macrophyte taxonomic composition and seagrass biometrics in the temperate Baltic Sea eelgrass meadows. We hypothesize that the anticipated strong seasonality in vegetation cover induces parallel seasonal changes in seagrass engineering effects as indicated by changes in sediment characteristics and meiozoobenthic abundance, composition and diversity. Macrophytes, sediments, and fauna were sampled at two locations in the Puck Bay from vegetated bottoms and bare sands five times in one year. Zostera marina vegetation occurred throughout the year and showed strong seasonality with the highest values of shoot density, leaf length, and biomass in July (202.3 ± 30.0 95% CI shoots m-2) and the lowest in March (55.4 ± 15.0 shoots m-2). POC was significantly higher in vegetated sands, and these effects were evident throughout the study period regardless of variability in macrophyte vegetation. The density and diversity of meiofauna did not differ between the seagrass beds and bare sands even in summer months when vegetation was best developed. The lack of an effect of the seagrass meadows on the meiofauna can be explained by the relatively low shoot density and biomass of the studied seagrass meadows and/or higher macrobenthic predation on the vegetated bottom compared to bare sands. However, both the canopies of macrophytes and the effects of the vegetation on benthic systems could increase substantially over the course of the gradual, natural restoration of the seagrass meadows.

  4. Local competition and metapopulation processes drive long-term seagrass-epiphyte population dynamics.

    Science.gov (United States)

    Lobelle, Delphine; Kenyon, Emma J; Cook, Kevan J; Bull, James C

    2013-01-01

    It is well known that ecological processes such as population regulation and natural enemy interactions potentially occur over a range of spatial scales, and there is a substantial body of literature developing theoretical understanding of the interplay between these processes. However, there are comparatively few studies quantifying the long-term effects of spatial scaling in natural ecosystems. A key challenge is that trophic complexity in real-world biological communities quickly obscures the signal from a focal process. Seagrass meadows provide an excellent opportunity in this respect: in many instances, seagrasses effectively form extensive natural monocultures, in which hypotheses about endogenous dynamics can be formulated and tested. We present amongst the longest unbroken, spatially explict time series of seagrass abundance published to date. Data include annual measures of shoot density, total above-ground abundance, and associated epiphyte cover from five Zostera marina meadows distributed around the Isles of Scilly, UK, from 1996 to 2011. We explore empirical patterns at the local and metapopulation scale using standard time series analysis and develop a simple population dynamic model, testing the hypothesis that both local and metapopulation scale feedback processes are important. We find little evidence of an interaction between scales in seagrass dynamics but that both scales contribute approximately equally to observed local epiphyte abundance. By quantifying the long-term dynamics of seagrass-epiphyte interactions we show how measures of density and extent are both important in establishing baseline information relevant to predicting responses to environmental change and developing management plans. We hope that this study complements existing mechanistic studies of physiology, genetics and productivity in seagrass, whilst highlighting the potential of seagrass as a model ecosystem. More generally, this study provides a rare opportunity to test

  5. Low-canopy seagrass beds still provide important coastal protection services.

    Science.gov (United States)

    Christianen, Marjolijn J A; van Belzen, Jim; Herman, Peter M J; van Katwijk, Marieke M; Lamers, Leon P M; van Leent, Peter J M; Bouma, Tjeerd J

    2013-01-01

    One of the most frequently quoted ecosystem services of seagrass meadows is their value for coastal protection. Many studies emphasize the role of above-ground shoots in attenuating waves, enhancing sedimentation and preventing erosion. This raises the question if short-leaved, low density (grazed) seagrass meadows with most of their biomass in belowground tissues can also stabilize sediments. We examined this by combining manipulative field experiments and wave measurements along a typical tropical reef flat where green turtles intensively graze upon the seagrass canopy. We experimentally manipulated wave energy and grazing intensity along a transect perpendicular to the beach, and compared sediment bed level change between vegetated and experimentally created bare plots at three distances from the beach. Our experiments showed that i) even the short-leaved, low-biomass and heavily-grazed seagrass vegetation reduced wave-induced sediment erosion up to threefold, and ii) that erosion was a function of location along the vegetated reef flat. Where other studies stress the importance of the seagrass canopy for shoreline protection, our study on open, low-biomass and heavily grazed seagrass beds strongly suggests that belowground biomass also has a major effect on the immobilization of sediment. These results imply that, compared to shallow unvegetated nearshore reef flats, the presence of a short, low-biomass seagrass meadow maintains a higher bed level, attenuating waves before reaching the beach and hence lowering beach erosion rates. We propose that the sole use of aboveground biomass as a proxy for valuing coastal protection services should be reconsidered.

  6. Top-down control of epifauna by fishes enhances seagrass production.

    Science.gov (United States)

    Lewis, Levi S; Anderson, Todd W

    2012-12-01

    Predators can influence the structure and function of ecosystems by altering the composition or behavior of herbivore communities. Overexploitation of predators, therefore, may lead to habitat loss by altering important top-down interactions that facilitate habitat-forming species. In seagrass beds, top-down control of algal growth by mesograzers appears to facilitate seagrass production. The indirect consequences of higher-order trophic interactions, however, remain unclear. Although predators may limit the beneficial effects of algal mesograzers, it is also possible that they limit the abundance of invertebrates that consume and foul seagrasses. We used experimental enclosure and exclosure cages to explore the direct and indirect effects of microcarnivorous fishes on epifaunal invertebrates, epiphytic loads, and seagrass growth in a natural eelgrass (Zostera marina) bed in San Diego Bay, California, USA. Contrary to expectations, when fishes were excluded, invertebrate abundance increased by 300-1000%, fouling on eelgrass leaves increased by 600%, and eelgrass production declined by 50%. Despite high densities of predators in enclosures, subsequent effects did not differ from ambient conditions. When predators were excluded, however, abundances of epifauna (including tube-building crustaceans and an eelgrass-grazing limpet) increased dramatically, resulting in reduced seagrass production. Our results are supported by several studies of eelgrass communities in the northeastern Pacific, characterized by coastal upwelling, inverse estuaries, and a voracious seagrass-consuming limpet. These strong, positive, indirect effects of microcarnivores on seagrass production contrast with the beneficial mesograzer paradigm, highlighting the need for hypotheses to be tested across a variety of ecosystems with varying biophysical characteristics.

  7. Seagrass stems with attached roots from the type area of the Maastrichtian Stage (NE Belgium, SE Netherlands) : Morphology, anatomy, and ecological aspects

    NARCIS (Netherlands)

    van der Ham, R.W.J.M.; van Konijnenburg-van Cittert, J.H.A.; Jagt, J.W.M.; Indeherberge, L.; Meuris, R.; Deckers, M.J.M.; Renkens, S.; Laffineur, J.

    2017-01-01

    Seagrasses are the only seed plants to have invaded marine environments successfully. Seagrass fossils are both rare and have received scant attention so far. However, among the limited number of plant fossils from marine strata in the Maastrichtian type area, remains of seagrasses are relatively co

  8. Early warning indicators for river nutrient and sediment loads in tropical seagrass beds: A benchmark from a near-pristine archipelago in Indonesia

    NARCIS (Netherlands)

    Van Katwijk, M.; Van der Welle, M.E.W.; Lucassen, E.C.H.E.T.; Vonk, J.A.; Christianen, M.J.A.; Kiswara, W.; Inayat al Hakim, I.; Arifin, A.; Bouma, T.J.; Roelofs, J.G.M.; Lamers, L.P.M.

    2011-01-01

    In remote, tropical areas human influences increase, potentially threatening pristine seagrass systems. We aim (i) to provide a bench-mark for a near-pristine seagrass system in an archipelago in East Kalimantan, by quantifying a large spectrum of abiotic and biotic properties in seagrass meadows

  9. Seagrass stems with attached roots from the type area of the Maastrichtian Stage (NE Belgium, SE Netherlands) : Morphology, anatomy, and ecological aspects

    NARCIS (Netherlands)

    van der Ham, R.W.J.M.; van Konijnenburg-van Cittert, J.H.A.; Jagt, J.W.M.; Indeherberge, L.; Meuris, R.; Deckers, M.J.M.; Renkens, S.; Laffineur, J.

    Seagrasses are the only seed plants to have invaded marine environments successfully. Seagrass fossils are both rare and have received scant attention so far. However, among the limited number of plant fossils from marine strata in the Maastrichtian type area, remains of seagrasses are relatively

  10. Use of semi-quantitative kit methods to study the heterotrophic bacterial community of Posidonia oceanica meadows: Limits and possible applications

    Science.gov (United States)

    Richir, J.; Velimirov, B.; Poulicek, M.; Gobert, S.

    2012-08-01

    Rapid, easy and low cost semi-quantitative methods were tested to study the heterotrophic bacterial community of Posidonia oceanica meadows and were compared to techniques commonly used in microbial ecology. Free and pore-water bacterial densities were estimated by luminescence, and principal enzymatic activities, metabolic capabilities and benthic mineralisation processes were studied with microtitration methods: ApiZym galleries, Biolog microplates and BART™ tests. Bacterial densities varied little throughout the year and were around 5.0·105 and 6.0·106 cells ml-1 of free and pore-water, respectively. The combined use of the ApiZym gallery and the Biolog microtitration plate permitted highlighting bacterial enzymatic activities susceptible to degrade principal organic polymers present in the Posidonia meadow, and to correlate these enzymatic activities to the subsequent potential utilization of resulting monomeric products. Levels of enzymatic activities (1.80-8.36 nmolessubstrates h-1 ml-1) and energetic bacterial metabolism (1.80-6.42 nmolessubstrates h-1 ml-1) presented seasonality relying on the temperature regime and on the primary production (Posidonia and phytoplankton). Main mineralization processes of buried organic matter through sulfate and iron reduction activities were successfully detected. Despite the complexity of the studied ecosystem, results obtained by this semi-quantitative approach, compared to studies applying commonly used methods in microbial ecology, highlighted the same bacterial dominant key processes. Their low cost, rapid and easy use, and the low level of expertise and sophistication they require means that these techniques are of use to many employed in environmental surveys.

  11. Efecto de una posible interacción entre el pH y la salinidad sobre el crecimiento de Posidonia oceanica (L.) Delile, 1813

    OpenAIRE

    Fernández-Torquemada, Yolanda; Sánchez-Lizaso, José Luis

    2003-01-01

    La desalación de aguas marinas mediante ósmosis inversa es una actividad en desarrollo en la cuenca mediterránea cuyos posibles impactos ambientales son poco conocidos. El agua de rechazo de dichas plantas posee una elevada salinidad y un pH relativamente bajo. En el presente trabajo se realizaron experimentos en mesocosmos para estimar el efecto de una posible interacción entre dicho descenso del pH y el incremento de la salinidad sobre el crecimiento de la fanerógama marina Posidonia oce...

  12. Large-Scale Prediction of Seagrass Distribution Integrating Landscape Metrics and Environmental Factors: The Case of Cymodocea nodosa (Mediterranean–Atlantic)

    KAUST Repository

    Chefaoui, Rosa M.

    2015-05-05

    Understanding the factors that affect seagrass meadows encompassing their entire range of distribution is challenging yet important for their conservation. Here, we predict the realized and potential distribution for the species Cymodocea nodosa modelling its environmental niche in the Mediterranean and adjacent Atlantic coastlines. We use a combination of environmental variables and landscape metrics to perform a suite of predictive algorithms which enables examination of the niche and find suitable habitats for the species. The most relevant environmental variables defining the distribution of C. nodosa were sea surface temperature (SST) and salinity. We found suitable habitats at SST from 5.8 °C to 26.4 °C and salinity ranging from 17.5 to 39.3. Optimal values of mean winter wave height ranged between 1.2 and 1.5 m, while waves higher than 2.5 m seemed to limit the presence of the species. The influence of nutrients and pH, despite having weight on the models, was not so clear in terms of ranges that confine the distribution of the species. Landscape metrics able to capture variation in the coastline enhanced significantly the accuracy of the models, despite the limitations caused by the scale of the study. We found potential suitable areas not occupied by the seagrass mainly in coastal regions of North Africa and the Adriatic coast of Italy. The present study describes the realized and potential distribution of a seagrass species, providing the first global model of the factors that can be shaping the environmental niche of C. nodosa throughout its range. We identified the variables constraining its distribution as well as thresholds delineating its environmental niche. Landscape metrics showed promising prospects for the prediction of coastal species dependent on the shape of the coast. By contrasting predictive approaches, we defined the variables affecting the distributional areas that seem unsuitable for C. nodosa as well as those suitable habitats not

  13. Interrogating the Mediterranean 'Migration Crisis'

    NARCIS (Netherlands)

    Pallister-Wilkins, P.

    2016-01-01

    This Forum aims to uncover the socio-politics of the ‘migration crisis’ in the Mediterranean. The contributions explore the idea of the ‘migration crisis’ or ‘refugee crisis’ in the Mediterranean from the starting point that as scholars of the Mediterranean we can do two things: one, we can look at

  14. Processes affecting the spatial distribution of seagrass meadow sedimentary material on Yao Yai Island, Thailand

    Science.gov (United States)

    Quak, Michelle S. Y.; Ziegler, Alan D.; Benner, Shawn G.; Evans, Sam; Todd, Peter A.; Gillis, Lucy G.; Vongtanaboon, Sukanya; Jachowski, Nick; Bouma, Tjeerd J.

    2016-12-01

    Many islands throughout SE Asia are experiencing rapid development and land-cover conversion that potentially threaten sensitive coastal ecosystems, such as seagrasses, through increased loading of sediment and nutrients originating from disturbed catchments draining to the sea. To evaluate this threat for one such island in Southern Thailand (Yao Yai), we perform sediment source tracing via end-member mixing analysis using stable isotopes δ13C and δ15N in organic matter to explore sediment loading in a seagrass meadow. The analysis indicates that sedimentary material in the meadow originates mostly from ocean-associated sources (∼62% from seagrass detritus, seston, and ocean sediments). Terrestrial material comprises ∼19% of the organic material found in the seagrass meadow, with another 20% originating from an adjacent mangrove forest. Approximately one-fourth of the seagrass meadow material (24%) is detritus that has been (re)deposited internally. The high contribution of terrestrial-derived organic matter deposited near the river mouth demonstrates that substantial quantities of sediment are being transferred from upslope erosion sources into the seagrass meadow. However, only a small amount of this material is deposited throughout the entire bay because much of the terrestrial- and mangrove-derived sediment is transferred to the open ocean via channels that are periodically dredged to allow boat access to two small inland harbours. This positive affect of dredging has not received very much attention in existing literature. River water flowing to the channels during falling tide delivers sediment to these efficient pathways, where much of it bypasses the seagrass meadow at periods of time when sediment deposition would normally be the greatest. There is growing concern that ongoing land-cover changes and planned urbanization related to tourism and agriculture on the island may boost sediment/nutrients above a critical threshold, beyond that revealed in

  15. Factors influencing landscape pattern of the seagrass Halophila decipiens in an oceanic setting

    Science.gov (United States)

    Fonseca, Mark S.; Kenworthy, W. Judson; Griffith, Emily; Hall, Margaret O.; Finkbeiner, Mark; Bell, Susan S.

    2008-01-01

    The scale of landscape pattern formation of an ecological community may provide clues as to the processes influencing its spatial and temporal dynamics. We conducted an examination of the spatial organization of an annual seagrass ( Halophila decipiens) in an open ocean setting at two spatial scales and growing seasons to identify the relative influence of external (hurricanes) versus internal (clonal growth) factors. Visual surveys of seagrass cover were conducted over 2 years within three replicate 1 km 2 study areas each separated by ˜25 km in an inshore-offshore transect along the southwest coast of Florida at depths between ˜10 and 30 m. A towed video sled allowed observations of seagrass cover of 1 m 2 areas approximately every 6 m over thousands of meters of evenly spaced transects within the study areas (coarse scale). The towed video revealed that 17.5% of the seafloor was disturbed irrespective of location or sample time. Randomly selected 10 × 10 m quadrats within the larger, 1 km 2 study areas were completely surveyed for seagrass cover by divers at 0.625 m 2 resolution (fine scale). The coarse-scale observations were tested using both conventional geostatistics and an application of a time-series technique (Runs test) for scale of seagrass cover contiguity. Fine-scale observations were examined using conventional geostatistics and a least squares approach (cumulative logistic). The coarse-scale observations revealed little scale dependency and indicated that the structure was organized at spatial extents finer than our sample spacing; the cumulative logistic technique revealed potential fine-scale patterns not otherwise discerned. In contrast, surveys of the 10 × 10 m quadrats detected strong scale dependency with multiple small gaps, indicating scale-dependent patterns arising from processes operating at extents generally seeds. Spatial analysis revealed that the storm led to a shift to greater frequency of H. decipiens, but lower density coverage

  16. Lethal and sub-lethal chronic effects of the herbicide diuron on seagrass.

    Science.gov (United States)

    Negri, Andrew P; Flores, Florita; Mercurio, Phil; Mueller, Jochen F; Collier, Catherine J

    2015-08-01

    Photosystem II herbicides from agricultural sources have been detected throughout nearshore tropical habitats including seagrass meadows. While PSII herbicides have been shown to inhibit growth in microalgae at low concentrations, the potential impacts of chronic low concentration exposures to seagrass health and growth have not been investigated. Here we exposed two tropical seagrass species Halodule uninervis and Zostera muelleri to elevated diuron concentrations (from 0.3 to 7.2μgl(-1)) over a 79-day period followed by a 2-week recovery period in uncontaminated seawater. PAM fluorometry demonstrated rapid effect of diuron on photosystem II (PSII) in both seagrass species at 0.3μgl(-1). This effect included significant inhibition of photosynthetic efficiency (ΔF/Fm') and inactivation of PSII (Fv/Fm) over the 11 week exposure period. Significant mortality and reductions in growth was only observed at the highest exposure concentration of 7.2μgl(-1) diuron. However, biochemical indicators demonstrated that the health of seagrass after this prolonged exposure was significantly compromised at lower concentrations. For example, the drop in C:N ratios (0.6μgl(-1)) and reduced δ(13)C (1.7μgl(-1)) in seagrass leaves indicated reduced C-assimilation from photosynthesis. Critically, the energetic reserves of the plants (as measured by starch content in the root-rhizome complex) were approximately halved following diuron exposure at and above 1.7μgl(-1). During the 2-week recovery period, the photosynthetic capacity of the seagrass improved with only plants from the highest diuron treatment still exhibiting chronic damage to PSII. This study shows that, although seagrass may survive prolonged herbicide exposures, concentrations ≥0.6μgl(-1) diuron equivalents cause measureable impacts on energetic status that may leave the plants vulnerable to other simultaneous stressors. For example, tropical seagrasses have been heavily impacted by reduced light from coastal

  17. Understanding uncertainty in seagrass injury recovery: an information-theoretic approach.

    Science.gov (United States)

    Uhrin, Amy V; Kenworthy, W Judson; Fonseca, Mark S

    2011-06-01

    Vessel groundings cause severe, persistent gaps in seagrass beds. Varying degrees of natural recovery have been observed for grounding injuries, limiting recovery prediction capabilities, and therefore, management's ability to focus restoration efforts where natural recovery is unlikely. To improve our capacity for predicting seagrass injury recovery, we used an information-theoretic approach to evaluate the relative contribution of specific injury attributes to the natural recovery of 30 seagrass groundings in Florida Keys National Marine Sanctuary, Florida, USA. Injury recovery was defined by three response variables examined independently: (1) initiation of seagrass colonization, (2) areal contraction, and (3) sediment in-filling. We used a global model and all possible subsets for four predictor variables: (1) injury age, (2) original injury volume, (3) original injury perimeter-to-area ratio, and (4) wave energy. Successional processes were underway for many injuries with fast-growing, opportunistic seagrass species contributing most to colonization. The majority of groundings that exhibited natural seagrass colonization also exhibited areal contraction and sediment in-filling. Injuries demonstrating colonization, contraction, and in-filling were on average older and smaller, and they had larger initial perimeter-to-area ratios. Wave energy was highest for colonizing injuries. The information-theoretic approach was unable to select a single "best" model for any response variable. For colonization and contraction, injury age had the highest relative importance as a predictor variable; wave energy appeared to be associated with second-order effects, such as sediment in-filling, which in turn, facilitated seagrass colonization. For sediment in-filling, volume and perimeter-to-area ratio had similar relative importance as predictor variables with age playing a lesser role than seen for colonization and contraction. Our findings confirm that these injuries

  18. Depth-acclimation of photosynthesis, morphology and demography of Posidonia oceanica and Cymodocea nodosa in the Spanish Mediterranean Sea

    DEFF Research Database (Denmark)

    Olesen, B.; Enríquez, Susana; Duarte, Carlos M.

    2002-01-01

    and roots at greater depths, thereby promoting the balance between photosynthesis and respiration in the shoots. C. nodosa, being a potentially fast-growing species compared to P. oceanica, had higher maximum photosynthetic and respiration rates as well as light compensation points for photosynthesis....... Photosynthetic efficiency at low light, however, was almost the same for the 2 species as suggested by the relatively small differences in mass-specific light absorption. Only C. nodosa acclimated physiologically to depth as light-use efficiency increased, and light compensation point declined significantly from...... shallow to deep water. P. oceanica, however, possessed low respiration rates and slightly lower light compensation points values than C. nodosa throughout the depth range. Shoot mortality and recruitment rates were unaffected by rooting depth. C. nodosa stand experienced fast shoot turnover compared to P...

  19. Contrasting metabolic patterns among seagrass and sand-bottom habitats: relative roles of plankton and benthic metabolism

    Science.gov (United States)

    Human activities can alter the ecological function of estuaries, affecting the ecosystem metabolic balance, which in turn dictates the magnitude and mode of organic matter accumulation. Because human perturbations can cause a loss of seagrass habitat, seagrasses can be a sensitiv...

  20. Groundwater effects on diversity and abundance of lagoonal seagrasses in Kenya and on Zanzibar Island (East Africa)

    NARCIS (Netherlands)

    Kamermans, P.; Hemminga, M.A.; Tack, J.F.; Mateo, M.A.; Marbà, N.; Mtolera, M.; Stapel, J.; Verheyden, A.; Van Daele, T.

    2002-01-01

    Seagrass species diversity and abundance were studied in East African back-reef lagoons with contrasting groundwater-outflow rates. The selection of the lagoons was based on a groundwater flow model. A total of 10 seagrass species was observed at all sites together. Sites with a higher groundwater

  1. The effect of oyster aquaculture on seagrass (Zostera marina) at the estuarine landscape scale in Willapa Bay, Washington (USA)

    Science.gov (United States)

    Both seagrasses and bivalve shellfish provide valuable ecosystem services including nursery habitat in estuaries worldwide. Seagrasses are protected by no-net-loss provisions in US federal and state regulations resulting in a precautionary approach by managers that avoids any direct impacts from d...

  2. Effects of Nutrient Enrichment on Primary Production and Biomass of Sediment Microalgae in a Subtropical Seagrass Bed

    Science.gov (United States)

    Eutrophication of coastal waters often leads to excessive growth of microalgal epiphytes attached to seagrass leaves; however, the effect of increased nutrient levels on sediment microalgae has not been studied within seagrass communities. A slow-release NPK Osmocote fertilizer was added to sedimen...

  3. The Great Barrier Reef World Heritage Area seagrasses: Managing this iconic Australian ecosystem resource for the future

    Science.gov (United States)

    Coles, Robert G.; Rasheed, Michael A.; McKenzie, Len J.; Grech, Alana; York, Paul H.; Sheaves, Marcus; McKenna, Skye; Bryant, Catherine

    2015-02-01

    The Great Barrier Reef World Heritage Area (GBRWHA) includes one of the world's largest areas of seagrass (35,000 km2) encompassing approximately 20% of the world's species. Mapping and monitoring programs sponsored by the Australian and Queensland Governments and Queensland Port Authorities have tracked a worrying decrease in abundance and area since 2007. This decline has almost certainly been the result of a series of severe tropical storms and associated floods exacerbating existing human induced stressors. A complex variety of marine and terrestrial management actions and plans have been implemented to protect seagrass and other habitats in the GBRWHA. For seagrasses, these actions are inadequate. They provide an impression of effective protection of seagrasses; reduce the sense of urgency needed to trigger action; and waste the valuable and limited supply of "conservation capital". There is a management focus on ports, driven by public concerns about high profile development projects, which exaggerates the importance of these relatively concentrated impacts in comparison to the total range of threats and stressors. For effective management of seagrass at the scale of the GBRWHA, more emphasis needs to be placed on the connectivity between seagrass meadow health, watersheds, and all terrestrial urban and agricultural development associated with human populations. The cumulative impacts to seagrass from coastal and marine processes in the GBRWHA are not evenly distributed, with a mosaic of high and low vulnerability areas. This provides an opportunity to make choices for future coastal development plans that minimise stress on seagrass meadows.

  4. 15 CFR Appendix C to Subpart H of... - No-Anchoring Seagrass Protection Zones in Tomales Bay

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false No-Anchoring Seagrass Protection Zones in Tomales Bay C Appendix C to Subpart H of Part 922 Commerce and Foreign Trade Regulations Relating... 922—No-Anchoring Seagrass Protection Zones in Tomales Bay Coordinates listed in this Appendix...

  5. Nutrient dynamics in Indonesian seagrass beds : factors determining conservation and loss of nitrogen and phosp[h]orus

    NARCIS (Netherlands)

    Stapel, J.

    1997-01-01

    Seagrasses are marine angiosperms that occur in shallow coastal seas around the world. They have reached their highest species diversity in Southeast Asia, where they formextensive multi-species meadows. The seagrass beds in Indonesia maintain a high productivity despite a low nu

  6. Biogeography of Mediterranean Invasions

    Science.gov (United States)

    Groves, R. H.; di Castri, F.

    The Mediterranean basin, California, Chile, the western Cape of South Africa, and southern Australia share a Mediterranean climate characterized by cool, wet winters and hot, dry summers. These five regions have differing patterns of human settlement, but similarities in natural vegetation and some faunal assemblages. These likenesses are enhanced with time by an increasing level of biotic exchange among the regions. An initiative of a subcommittee of SCOPE (Scientific Committee on Problems of the Environment), which realized that the integrity of many natural ecosystems is being threatened by the ingress of invasive species, this book uniquely documents the introduced floras and faunas, especially plants, buds, and mammals, in these five regions of Mediterranean climate, and aims to increase our understanding of the ecology of biological invasions. In doing so, it points a way to more effectively manage the biota of these regions.

  7. Use of digital multispectral videography to assess seagrass distribution in San Quintin Bay, Baja California, Mexico

    Science.gov (United States)

    Ward, D.H.; Tibbitts, T.L.; Morton, Alexandra; Carrera-Gonzalez, Eduardo; Kempka, R.

    2004-01-01

    Apparent threats to the spatial distribution of seagrass in San Quinti??n Bay prompted us to make a detailed assessment of habitats in the bay. Six coastal habitats and three seagrass subclasses were delineated using airborne digital multispectral videography (DMSV), Eelgrass, Zostera marina, was the predominant seagrass and covered 40% (1949 ha) of the areal extent of the bay in 1999. Eelgrass grew over a wide range of tidal depths from about -3.0 in mean lower low water (MLLW) to about 1.0 m MLLW, but greatest spatial extent occurred in intertidal areas -0.6 m to 1.0 m MLLW. Exposed-continuous (i.e., high density) eelgrass was the most abundant habitat in the bay. Widgeongrass, Ruppia maritima, was the only other seagrass present and covered 3% (136 ha) of the areal extent of the entire bay. Widgeongrass grew in single species stands in the upper intertidal (??? 0.4 MLLW) and intermixed with eelgrass at lower tidal depths. Overall accuracy of the six habitat classes and three subclasses in the DMSV map was relatively high at 84%. Our detailed map of San Quintin Bay can be used in future change detection analyses to monitor the health of seagrasses in the bay.

  8. Genome-wide survey of the seagrass Zostera muelleri suggests modification of the ethylene signalling network.

    Science.gov (United States)

    Golicz, Agnieszka A; Schliep, Martin; Lee, Huey Tyng; Larkum, Anthony W D; Dolferus, Rudy; Batley, Jacqueline; Chan, Chon-Kit Kenneth; Sablok, Gaurav; Ralph, Peter J; Edwards, David

    2015-03-01

    Seagrasses are flowering plants which grow fully submerged in the marine environment. They have evolved a range of adaptations to environmental challenges including light attenuation through water, the physical stress of wave action and tidal currents, high concentrations of salt, oxygen deficiency in marine sediment, and water-borne pollination. Although, seagrasses are a key stone species of the costal ecosystems, many questions regarding seagrass biology and evolution remain unanswered. Genome sequence data for the widespread Australian seagrass species Zostera muelleri were generated and the unassembled data were compared with the annotated genes of five sequenced plant species (Arabidopsis thaliana, Oryza sativa, Phoenix dactylifera, Musa acuminata, and Spirodela polyrhiza). Genes which are conserved between Z. muelleri and the five plant species were identified, together with genes that have been lost in Z. muelleri. The effect of gene loss on biological processes was assessed on the gene ontology classification level. Gene loss in Z. muelleri appears to influence some core biological processes such as ethylene biosynthesis. This study provides a foundation for further studies of seagrass evolution as well as the hormonal regulation of plant growth and development.

  9. Toxic effects of increased sediment nutrient and organic matter loading on the seagrass Zostera noltii.

    Science.gov (United States)

    Govers, Laura L; de Brouwer, Jan H F; Suykerbuyk, Wouter; Bouma, Tjeerd J; Lamers, Leon P M; Smolders, Alfons J P; van Katwijk, Marieke M

    2014-10-01

    As a result of anthropogenic disturbances and natural stressors, seagrass beds are often patchy and heterogeneous. The effects of high loads of nutrients and organic matter in patch development and expansion in heterogeneous seagrass beds have, however, poorly been studied. We experimentally assessed the in situ effects of sediment quality on seagrass (Zostera noltii) patch dynamics by studying patch (0.35 m diameter) development and expansion for 4 sediment treatments: control, nutrient addition (NPK), organic matter addition (OM) and a combination (NPK+OM). OM addition strongly increased porewater sulfide concentrations whereas NPK increased porewater ammonium, nitrate and phosphate concentrations. As high nitrate concentrations suppressed sulfide production in NPK+OM, this treatment was biogeochemically comparable to NPK. Sulfide and ammonium concentrations differed within treatments, but over a 77 days period, seagrass patch survival and expansion were impaired by all additions compared to the control treatment. Expansion decreased at porewater ammonium concentrations >2,000 μmol L(-1). Mother patch biomass was not affected by high porewater ammonium concentrations as a result of its detoxification by higher seagrass densities. Sulfide concentrations >1,000 μmol L(-1) were toxic to both patch expansion and mother patch. We conclude that patch survival and expansion are constrained at high loads of nutrients or organic matter as a result of porewater ammonium or sulfide toxicity.

  10. Mediterranean, our sea

    Science.gov (United States)

    Markaki, Foteini

    2017-04-01

    My school (1o EPAL Ymittos -Athens, Greece) is a technical school of secondary education and throughout this school year being drafted a program of environmental education. The main theme is the Mediterranean Sea, the biggest closed sea extending between three continents. Topics studied: 1. Biodiversity and the risks threat. 2. The geophysics that characterize (earthquakes, volcanoes explosions, etc). 3. The Mediterranean Sea as environment anthropogenesis, a mosaic of other cultures and even place current notions of social phenomena (refugees). Pedagogical Objectives: Cognitive/Enviromental: 1. To investigate and understand the biodiversity of the Mediterranean Sea and the risks to threaten and phenomena that characterize. 2. To understand the position of the Mediterranean Sea in the land and the role of the historical, cultural and social human environment. 3. To come in contact with texts literary, social, articles on the Mediterranean. Psychomotor: 1. To work together and collect information for the Mediterranean Sea. 2. Experiential approach to the natural environment. 3. Develop critical thinking. 4. Undertake responsibilities for the presentation of the program. Emotional: 1. To feel joy from participation in the program. 2. Being sensitized and configure attitudes and actions of respect towards the environment. Methodology implementation: Teamwork. Interdisciplinary - holistic to dissemination of program recordings to courses curriculum. Study in the field. Gathering information from newspapers, magazines, internet, maps, and photographs. Experiential method- Project. Assessment methods and self-assessment. Fields of courses: Greek language- History- Biology- Chemistry- Technology Dissemination of results: Make a page of social media (facebook), a blog, enhancing environmental awareness via video, make an electronic poster.

  11. MICROHABITAT USE AND MULTIVARIATE PATTERN OF MOTILE EPIFAUNAL COMMUNITY IN RELATION TO SEDIMENT GRAIN SIZE IN A TROPICAL SEAGRASS MEADOW

    Directory of Open Access Journals (Sweden)

    PENAGOS GUILLERMO

    2010-05-01

    Full Text Available The relationship between habitat physical structure and motile epifauna community associated to a Seagrass bed dominated by Thalassia testudinum was study over the isobaths of 1 and 3 m, in terms of species diversity, organisms density, micro habitat use and multivariate species pattern in association with Seagrass biomass, shoot and leaf density, leaves long and wide, epiphytic and rizophytic algae biomass, sponges biomass and sediment grain size. Seagrass features showed significant differences between depths, instead epiphytic and rizophytic algae, sponges biomass and sediment grain size did not. Though differences exhibited by Seagrass, epifaunal species diversity and organism density neither were different between depths. In the same way none Seagrass feature showed strong correlations with faunal descriptors, tending even to be negative instead positive.

  12. Trophic implications and faunal resilience following one-off and successive disturbances to an Amphibolis griffithii seagrass system.

    Science.gov (United States)

    Gartner, Adam; Lavery, Paul S; Lonzano-Montes, Hector

    2015-05-15

    Disturbances in seagrass systems often lead to considerable loss of seagrass fauna. We examined the capacity for seagrass fauna, across multiple trophic levels, to recover from disturbances, using empirical and modelling techniques. Model outputs, using Ecosim with Ecopath (EwE), were consistent with the results of field investigations, highlighting the models robustness. Modelled outcomes suggest second and third order consumers are likely to be negatively effected by disturbances in the seagrass canopy. Particularly piscivores, which once disturbed, appear unlikely to recover following severe declines in primary productivity. EwE also revealed the complex interaction between the duration and intensity of disturbances on seagrass fauna, which may differentially affect higher order consumers. Further, modelling predicted a variable capacity of higher order consumers to recover from successive disturbances, suggesting taxa with comparatively fast reproductive cycles and short generation terms would be more resilient than taxa with comparatively long generation terms and slow reproductive cycles.

  13. Contrasting recovery of shallow and deep water seagrass communities following climate associated losses in tropical north Queensland, Australia.

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    Rasheed, Michael A; McKenna, Skye A; Carter, Alexandra B; Coles, Robert G

    2014-06-30

    Tropical seagrass decline and recovery from severe storm impacts was assessed via quarterly measurements of seagrass biomass, species composition and experimental investigations of recovery in north Queensland. Shallow and deep seagrass meadows suffered major declines. Significant recovery in the two years following loss only occurred at deeper sites. Halophila spp. in deep water areas had a high capacity for recovery through the availability of seed banks. In contrast, the shallow species did not recover quickly from experimental disturbance, had poor seed reserves and relied on asexual propagation. The potential for shallow species to recover rapidly from widespread losses was limited as seed banks were limited or non-existent. Understanding inter- and intra-specific differences in seagrass recovery and how this interacts with location is critical to predict the consequences of climate events to tropical seagrasses. This is especially important as more frequent severe storms are predicted as a consequence of climate change.

  14. Habitat fragmentation has some impacts on aspects of ecosystem functioning in a sub-tropical seagrass bed.

    Science.gov (United States)

    Sweatman, Jennifer L; Layman, Craig A; Fourqurean, James W

    2017-05-01

    Habitat fragmentation impacts ecosystem functioning in many ways, including reducing the availability of suitable habitat for animals and altering resource dynamics. Fragmentation in seagrass ecosystems caused by propeller scarring is a major source of habitat loss, but little is known about how scars impact ecosystem functioning. Propeller scars were simulated in seagrass beds of Abaco, Bahamas, to explore potential impacts. To determine if plant-herbivore interactions were altered by fragmentation, amphipod grazers were excluded from half the experimental plots, and epiphyte biomass and community composition were compared between grazer control and exclusion plots. We found a shift from light limitation to phosphorus limitation at seagrass patch edges. Fragmentation did not impact top-down control on epiphyte biomass or community composition, despite reduced amphipod density in fragmented habitats. Seagrass and amphipod responses to propeller scarring suggest that severely scarred seagrass beds could be subject to changes in internal nutrient stores and amphipod distribution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Recovery of floral and faunal communities after placement of dredged material on seagrasses in Laguna Madre, Texas

    Science.gov (United States)

    Sheridan, P.

    2004-03-01

    The objectives of this project were to determine how long alterations in habitat characteristics and use by fishery and forage organisms were detectable at dredged material placement sites in Laguna Madre, Texas. Water, sediment, seagrass, benthos, and nekton characteristics were measured and compared among newly deposited sediments and nearby and distant seagrasses each fall and spring over three years. Over this period, 75% of the estimated total surface area of the original deposits was either re-vegetated by seagrass or dispersed by winds and currents. Differences in water and sediment characteristics among habitat types were mostly detected early in the study. There were signs of steady seagrass re-colonization in the latter half of the study period, and mean seagrass coverage of deposits had reached 48% approximately three years after dredging. Clovergrass Halophila engelmannii was the initial colonist, but shoalgrass Halodule wrightii predominated after about one year. Densities of annelids and non-decapod crustaceans were generally significantly greater in close and distant seagrass habitats than in dredged material habitat, whereas densities of molluscs were not significantly related to habitat type. Nekton (fish and decapod) densities were almost always significantly greater in the two seagrass habitats than in dredged material deposits. Benthos and nekton communities in dredged material deposits were distinct from those in seagrass habitats. Recovery from dredged material placement was nearly complete for water column and sediment components after 1.5 to 3 years, but recovery of seagrasses, benthos, and nekton was predicted to take 4 to 8 years. The current 2 to 5 years dredging cycle virtually insures no time for ecosystem recovery before being disturbed again. The only way to ensure permanent protection of the high primary and secondary productivity of seagrass beds in Laguna Madre from acute and chronic effects of maintenance dredging, while ensuring

  16. Seagrass and Submerged Aquatic Vegetation (VAS Habitats off the Coast of Brazil: state of knowledge, conservation and main threats

    Directory of Open Access Journals (Sweden)

    Margareth S. Copertino

    Full Text Available Abstract Seagrass meadows are among the most threatened ecosystems on earth, raising concerns about the equilibrium of coastal ecosystems and the sustainability of local fisheries. The present review evaluated the current status of the research on seagrasses and submerged aquatic vegetation (SAV habitats off the coast of Brazil in terms of plant responses to environmental conditions, changes in distribution and abundance, and the possible role of climate change and variability. Despite an increase in the number of studies, the communication of the results is still relatively limited and is mainly addressed to a national or regional public; thus, South American seagrasses are rarely included or cited in global reviews and models. The scarcity of large-scale and long-term studies allowing the detection of changes in the structure, abundance and composition of seagrass habitats and associated species still hinders the investigation of such communities with respect to the potential effects of climate change. Seagrass meadows and SAV occur all along the Brazilian coast, with species distribution and abundance being strongly influenced by regional oceanography, coastal water masses, river runoff and coastal geomorphology. Based on these geomorphological, hydrological and ecological features, we characterised the distribution of seagrass habitats and abundances within the major coastal compartments. The current conservation status of Brazilian seagrasses and SAV is critical. The unsustainable exploitation and occupation of coastal areas and the multifold anthropogenic footprints left during the last 100 years led to the loss and degradation of shoreline habitats potentially suitable for seagrass occupation. Knowledge of the prevailing patterns and processes governing seagrass structure and functioning along the Brazilian coast is necessary for the global discussion on climate change. Our review is a first and much-needed step toward a more integrated

  17. Using MODIS data for understanding changes in seagrass meadow health: a case study in the Great Barrier Reef (Australia).

    Science.gov (United States)

    Petus, Caroline; Collier, Catherine; Devlin, Michelle; Rasheed, Michael; McKenna, Skye

    2014-07-01

    Stretching more than 2000 km along the Queensland coast, the Great Barrier Reef Marine Park (GBR) shelters over 43,000 square km of seagrass meadows. Despite the status of marine protected area and World Heritage listing of the GBR, local seagrass meadows are under stress from reduced water quality levels; with reduction in the amount of light available for seagrass photosynthesis defined as the primary cause of seagrass loss throughout the GBR. Methods have been developed to map GBR plume water types by using MODIS quasi-true colour (hereafter true colour) images reclassified in function of their dominant colour. These data can be used as an interpretative tool for understanding changes in seagrass meadow health (as defined in this study by the seagrass area and abundance) at different spatial and temporal scales. We tested this method in Cleveland Bay, in the northern GBR, where substantial loss in seagrass area and biomass was detected by annual monitoring from 2007 to 2011. A strong correlation was found between bay-wide seagrass meadow area and biomass and exposure to turbid Primary (sediment-dominated) water type. There was also a strong correlation between the changes of biomass and area of individual meadows and exposure of seagrass ecosystems to Primary water type over the 5-year period. Seagrass meadows were also grouped according to the dominant species within each meadow, irrespective of location within Cleveland Bay. These consolidated community types did not correlate well with the exposure to Primary water type, and this is likely to be due to local environmental conditions with the individual meadows that comprise these groupings. This study proved that remote sensing data provide the synoptic window and repetitivity required to investigate changes in water quality conditions over time. Remote sensing data provide an opportunity to investigate the risk of marine-coastal ecosystems to light limitation due to increased water turbidity when in situ

  18. Study of the interaction mechanism in the biosorption of copper(II) ions onto posidonia oceanica and peat

    Energy Technology Data Exchange (ETDEWEB)

    Izquierdo, Marta; Marzal, Paula; Gabaldon, Carmen [Departamento de Ingenieria Quimica, Escuela Tecnica Superior de Ingenieria, Universitat de Valencia, Valencia (Spain); Silvetti, Margherita; Castaldi, Paola [Dipartimento di Scienze Ambientali e Agrarie e Biotecnologie Agro-Alimentari, Sez. Chimica Agraria ed Ambientale, University of Sassari, Sassari (Italy)

    2012-04-15

    A systematic approach was used to characterize the biosorption of copper(II) onto two biosorbents, Posidonia oceanica and peat, focusing on the interaction mechanisms, the copper(II) sorption-desorption process and the thermal behavior of the biosorbents. Sorption isotherms at pH 4-6 were obtained and the experimental data were fitted to the Langmuir model with a maximum uptake (q{sub max}) at pH 6 of 85.78 and 49.69 mg g{sup -1}, for P. oceanica and peat, respectively. A sequential desorption (SD) with water, Ca(NO{sub 3}){sub 2}, and EDTA was applied to copper-saturated biosorbents. Around 65-70% copper(II) were desorbed with EDTA, indicating that this heavy metal was strongly bound. The reversibility of copper(II) sorption was obtained by desorption with HCl and SD. Fourier transform IR spectroscopy (FTIR) analysis detected the presence of peaks associated with OH groups in aromatic and aliphatic structures, CH, CH{sub 2}, and CH{sub 3} in aliphatic structures, COO{sup -} and COOH groups and unsaturated aromatic structures on the surface of both biosorbents, as well as peaks corresponding to Si-O groups on the surface of peat. The results of SEM-EDX and FTIR analysis of copper-saturated samples demonstrated that ion exchange was one of the mechanisms involved in copper(II) retention. Thermal analysis of biosorbent samples showed that copper(II) sorption-desorption processes affected the thermal stability of the biosorbents. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. The protection of sandy shores - Can we afford to ignore the contribution of seagrass?

    Science.gov (United States)

    Paul, Maike

    2017-08-15

    Shore nourishment is considered an effective soft coastal protection measure for sandy shorelines. However, sand demand and costs are high, especially as nourishment has to be repeated regularly due to ongoing erosion. Seagrass meadows are able to trap and stabilise sediment by reducing bed shear stress. Moreover, they reduce flow velocity and wave energy in regions beyond their boundaries. Especially small species may not provide these ecosystem services sufficiently to protect shorelines from erosion, but they may stabilise beach profiles enough to increase nourishment intervals. This review discusses the potential benefits of integrating ecosystem services provided by seagrass meadows, both existing and newly planted, in nourishment plans, and also addresses potential limitations such as unsuitable hydrodynamic conditions and seasonality. Finally, it highlights knowledge gaps that should be addressed by interdisciplinary research to improve nourishment plans and use seagrass ecosystem services to their full potential. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. The Genome of a Southern Hemisphere Seagrass Species (Zostera muelleri)1[OPEN

    Science.gov (United States)

    Golicz, Agnieszka A.; Paterson, Andrew H.; Sablok, Gaurav; Krishnaraj, Rahul R.; Chan, Chon-Kit Kenneth; Batley, Jacqueline; Ralph, Peter J.

    2016-01-01

    Seagrasses are marine angiosperms that evolved from land plants but returned to the sea around 140 million years ago during the early evolution of monocotyledonous plants. They successfully adapted to abiotic stresses associated with growth in the marine environment, and today, seagrasses are distributed in coastal waters worldwide. Seagrass meadows are an important oceanic carbon sink and provide food and breeding grounds for diverse marine species. Here, we report the assembly and characterization of the Zostera muelleri genome, a southern hemisphere temperate species. Multiple genes were lost or modified in Z. muelleri compared with terrestrial or floating aquatic plants that are associated with their adaptation to life in the ocean. These include genes for hormone biosynthesis and signaling and cell wall catabolism. There is evidence of whole-genome duplication in Z. muelleri; however, an ancient pan-commelinid duplication event is absent, highlighting the early divergence of this species from the main monocot lineages. PMID:27373688

  1. Effects of tributyltin (TBT) on the seagrass Ruppia maritima.

    Science.gov (United States)

    Jensen, H F; Holmer, M; Dahllöf, I

    2004-10-01

    The effects of tributyltin (TBT) on the seagrass Ruppia maritima were studied in two growth experiments. Plants were sampled at stations in Odense Fjord and Lunkebugten, Denmark, and replanted in reference sediment without TBT, reference sediment spiked with TBT, and in impacted sediment sampled in the highly TBT contaminated (7-57 microg kg (-1) dw) Odense Fjord. Plant performance was studied at weekly intervals for 3-4 weeks, by measuring net photosynthetic activity, respiration, relative growth rate (RGR) and number of leaves. Net photosynthetic activity in plants from spiked and impacted sediment was reduced by up to 60% relative to reference plants. Respiration both increased and decreased in response to TBT exposure, while RGR was generally lower in plants from contaminated sediments (reduced by 8-25%). The effects of spiked and impacted sediment differed between the experiments, which could be partly explained by the bioavailability of TBT in the two treatments, but also by adaptation of the plants from Odense Fjord to TBT. Measurements of enhanced TBT concentrations in the sediments in Odense Fjord suggest an impact of TBT on R. maritima is possible under in situ conditions.

  2. Faunal Communities Are Invariant to Fragmentation in Experimental Seagrass Landscapes.

    Directory of Open Access Journals (Sweden)

    Jonathan S Lefcheck

    Full Text Available Human-driven habitat fragmentation is cited as one of the most pressing threats facing many coastal ecosystems today. Many experiments have explored the consequences of fragmentation on fauna in one foundational habitat, seagrass beds, but have either surveyed along a gradient of existing patchiness, used artificial materials to mimic a natural bed, or sampled over short timescales. Here, we describe faunal responses to constructed fragmented landscapes varying from 4-400 m2 in two transplant garden experiments incorporating live eelgrass (Zostera marina L.. In experiments replicated within two subestuaries of the Chesapeake Bay, USA across multiple seasons and non-consecutive years, we comprehensively censused mesopredators and epifaunal communities using complementary quantitative methods. We found that community properties, including abundance, species richness, Simpson and functional diversity, and composition were generally unaffected by the number of patches and the size of the landscape, or the intensity of sampling. Additionally, an index of competition based on species co-occurrences revealed no trends with increasing patch size, contrary to theoretical predictions. We extend conclusions concerning the invariance of animal communities to habitat fragmentation from small-scale observational surveys and artificial experiments to experiments conducted with actual living plants and