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See detailPer- and polyfluoroalkyl substances in plasma and feathers of nestling birds of prey from northern Norway
Gómez-Ramírez, P.; Bustnes, J. O.; Eulaers, I. et al

in Environmental Research (2017), 158

Plasma samples from nestlings of two top predators, White-tailed eagle (Haliaeetus albicilla) and Northern goshawk (Accipiter gentilis) from northern Norway were analysed for a wide range of per- and ... [more ▼]

Plasma samples from nestlings of two top predators, White-tailed eagle (Haliaeetus albicilla) and Northern goshawk (Accipiter gentilis) from northern Norway were analysed for a wide range of per- and polyfluoroalkyl substances (PFASs). Body feathers from the White-tailed eagles were also analysed and significant associations between specific PFASs in blood plasma and body feathers were found (0.36 < R2 < 0.67; all p < 0.05). This result suggests that analysing body feathers of White-tailed eagle could potentially be a useful non-invasive strategy to monitor PFASs exposure in nestlings of this species. White-tailed eagles showed significantly higher levels of contaminants than Northern goshawks (plasma ∑PFASs Median = 45.83 vs 17.02 ng mL−1, p <0.05). The different exposure between both species seemed to be related to different dietary input, as quantified by stable carbon and nitrogen isotope analysis of body feathers. A priori, the bird of prey populations studied are not at risk for PFASs, since the levels in plasma of both species were hundreds to thousand times lower than the toxic reference values reported for predatory birds. However, further studies on larger sample sizes are needed to confirm this hypothesis since toxic thresholds for nestling birds of prey are not established. [less ▲]

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See detailSoil erosion in relation to land use changes in the Amik Lake sediments near the Antioch antique city during the last 4kyr
El Ouahabi, Meriam ULiege; Hubert, Aurelia ULiege; Lebeau, Héléne et al

in The Holocene (2017)

The Amik Basin in the Eastern Mediterranean region occupied since 6000-7000 BC has sustained a highly variable anthropic pressure culminating during the Late Roman Period when the Antioch city reached its ... [more ▼]

The Amik Basin in the Eastern Mediterranean region occupied since 6000-7000 BC has sustained a highly variable anthropic pressure culminating during the Late Roman Period when the Antioch city reached its golden age. The present 6m long sedimentary record of the Amik Lake occupying the central part of the Basin constrains major paleo-environmental changes over the last 4000 years using a multi-proxy analyses (grain-size, magnetic susceptibility and XRF geochemistry). An age model is provided by combining short-lived radionuclides with radiocarbon dating. A lake/marsh prevailed during the last 4kyrs with a level increase at the beginning of the Roman Period possibly related to optimum climatic condition and water channelling. The Bronze/Iron Ages are characterized by a strong terrigenous input linked to deforestation, exploitation of mineral resources and the beginning of upland cultivation. The Bronze/Iron Age transition marked by the collapse of the Hittite Empire is clearly documented. Erosion continues during the Roman Period and nearly stopped during the Early Islamic Period in conjunction with a decreasing population and soil depletion on the calcareous highland. The soil-stripped limestone outcrops triggered an increase in CaO in the lake water, and a general decrease in ZrO2 released in the landscape that lasts until the present day. During the Islamic Period, pastoralism on the highland sustained continued soil erosion of the ophiolitic Amanus Mountains. The modern Period is characterized by a higher pressure particularly on the Amanus Mountains linked to deforestation, road construction, ore exploitation and the drying of the lake for agriculture practices. [less ▲]

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See detailInhibition of ethylene synthesis reduces salt-tolerance in tomato wild relative species Solanum chilense
Gharbi, E.; Martínez, J.-P.; Benahmed, H. et al

in Journal of Plant Physiology (2017), 210

Exposure to salinity induces a burst in ethylene synthesis in the wild tomato halophyte plant species Solanum chilense. In order to gain information on the role of ethylene in salt adaptation, plants of ... [more ▼]

Exposure to salinity induces a burst in ethylene synthesis in the wild tomato halophyte plant species Solanum chilense. In order to gain information on the role of ethylene in salt adaptation, plants of Solanum chilense (accession LA4107) and of cultivated glycophyte Solanum lycopersicum (cv. Ailsa Craig) were cultivated for 7 days in nutrient solution containing 0 or 125 mM NaCl in the presence or absence of the inhibitor of ethylene synthesis (aminovinylglycine (AVG) 2 μM). Salt-induced ethylene synthesis in S. chilense occurred concomitantly with an increase in stomatal conductance, an efficient osmotic adjustment and the maintenance of carbon isotope discrimination value (Δ13C). In contrast, in S. lycopersicum, salt stress decreased stomatal conductance and Δ13C values while osmotic potential remained higher than in S. chilense. Inhibition of stress-induced ethylene synthesis by AVG decreased stomatal conductance and Δ13C in S. chilense and compromised osmotic adjustment. Solanum chilense behaved as an includer and accumulated high amounts of Na in the shoot but remained able to maintain K nutrition in the presence of NaCl. This species however did not stimulate the expression of genes coding for high-affinity K transport but genes coding for ethylene responsive factor ERF5 and JREF1 were constitutively more expressed in S. chilense than in S. lycopersicum. It is concluded that ethylene plays a key role in salt tolerance of S. chilense. © 2016 [less ▲]

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See detailExtreme intra-clutch egg size dimorphism is not coupled with corresponding differences in antioxidant capacity and stable isotopes between eggs
Poisbleau, Maud; Beaulieu, Michaël; Dehnhard, Nina et al

in Comparative Biochemistry and Physiology Part A : Molecular & Integrative Physiology (2017), 205

Oviparous females need to allocate resources optimally to their eggs in order to maximize their fitness. Among these resources, dietary antioxidants, acquired by females and transferred to the eggs during ... [more ▼]

Oviparous females need to allocate resources optimally to their eggs in order to maximize their fitness. Among these resources, dietary antioxidants, acquired by females and transferred to the eggs during egg formation, can greatly affect the development and survival of the embryo and chick. In crested penguins, incubation starts after the second and last egg is laid and, as opposed to many other bird species, this egg hatches first, thereby enhancing the survival of the chick. Here, we assessed whether antioxidant and isotopic composition could underlie these differences between eggs within clutches of southern rockhopper penguins (Eudyptes chrysocome chrysocome). The second-laid egg had higher total antioxidant capacity than the first-laid egg, although this was not due to higher antioxidant concentration but to its higher mass. This suggests that resources are allocated by females at a constant rate in both eggs within clutches. Accordingly, we found a strong correlation for isotopic compositions between eggs suggesting that resources were allocated similarly to each egg within the clutch. Overall, we found little evidence for a significant role of antioxidant and isotopic compositions to explain differences in terms of embryo/chick development between eggs in crested penguins. However, since our results suggest a constant rate of antioxidant transfer from females to eggs, limiting the mass of the first-laid egg might represent a strategy for females to spare antioxidant defences and preserve self-maintenance. [less ▲]

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See detailTrophic ecology of Southern Ocean sea stars inferred from stable isotopes ratios of C and N
Le Bourg, Baptiste ULiege; Blanchard, Alice; Danis, Bruno et al

Conference (2016, December 17)

The Southern Ocean undergoes strong and contrasted impacts of climate change. Increasing seawater temperature and sea ice cover reduction in Western Antarctic Peninsula and associated regions will likely ... [more ▼]

The Southern Ocean undergoes strong and contrasted impacts of climate change. Increasing seawater temperature and sea ice cover reduction in Western Antarctic Peninsula and associated regions will likely impact food web structure and function. Sea stars (Echinoderms: Asteroidea) are an important group of the Southern Ocean benthos. They typically have highly variable feeding habits and are potentially more resistant than other organisms to temperature changes. Consequently, they will likely be impacted by modifications of the food web rather than by direct warming. Investigating their trophic ecology is therefore necessary to infer how climate change will impact them. In this context, the aim of this study was to use stable isotopes ratios of C, N and S to infer sea stars trophic ecology. During austral summers 2006 and 2009, sea stars were sampled in Subantarctic and Antarctic locations, with most of the samples coming from South Shetland Islands and South Georgia. The isotopic niche (proxy of the trophic niche) associated to each sea star population was explored through SIBER (Stable Isotope Bayesian Ellipses in R) metrics. Stable isotope ratios of sea stars were clearly different between South Shetland Islands and South Georgia. Sea stars of South Shetland Islands had smaller isotopic niches than sea stars of South Georgia. The overlap between the isotopic niches of sea star species was also important in South Shetland Islands, while isotopic niches of South Georgia were well separated. Difference of niche width and overlap between the two regions may be the result of different environmental conditions. In South Shetland Islands, sea star species may exploit a common benthic community relying on organic matter released during sea ice summer melting. In contrast, South Georgia is an oligotrophic environment with no sea ice. As resources are more limited, a higher trophic segregation between sea stars may appear to limit competition. Ultimately, this project highlighted the importance of sea ice in the trophic ecology of Antarctic sea stars. Our results suggest that future reduction of sea ice extent in Western Antarctica may have deleterious effect on sea star populations. [less ▲]

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See detailHead shape disparity of the cod icefishes Trematominae (Notothenioidei, Teleostei)
Frederich, Bruno ULiege; Heindler, Franz M.; Dettai, Agnès et al

Poster (2016, December 16)

The suborder Notothenioidei (Teleostei) has undergone a remarkable adaptive radiation in the Southern Ocean. Within this suborder, the subfamily Trematominae is endemic to Antarctic waters and represents ... [more ▼]

The suborder Notothenioidei (Teleostei) has undergone a remarkable adaptive radiation in the Southern Ocean. Within this suborder, the subfamily Trematominae is endemic to Antarctic waters and represents a dominant component of the shelf fish fauna. After recent advances in molecular phylogenetics, 14 species of Trematomus are currently recognized (including Pagothenia and Cryothenia spp.) comprising both considerable morphological and ecological diversity. Here, we aim to illustrate the main axes of shape variation in Trematomus and explore the evolution of their morphology. A dataset of 96 specimens representing 10 species of Trematomus from the collection of the Natural History Museum of Paris was assembled, and landmark-based geometric morphometrics was applied to quantify head shape disparity. Regular regression analysis revealed significant interspecific allometry while a low percentage of shape variation was explained by size (R2 = 0.11; P < 0.001). Main shape variation across species was explored using a principal component (PC) analysis on shape variables. Two groups diverged along PC1: (1) T. bernacchii, T. hansoni, T. pennellii and T. tokarevi have short cephalic profiles with larger cheeks (lowest values along PC1); and (2) T. lepidorhinus, T. eulepidotus and T. newnesi show lengthened cephalic profiles with larger eyes (highest values along PC1). Trematomus scotti differed from all other species mainly along PC3 indicating more elongated cheeks. Phenogram based on Procrustes shape distances will be compared to molecular phylogenetic trees and morphometric data will be mapped onto phylogenetic trees in order to illustrate the mode of phenotypic diversification of Trematomus during evolution. [less ▲]

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See detailWho would want to live in there? A history of Posidonia oceanica detritus accumulations, the associated invertebrate community, and its food web…
Remy, François ULiege; Michel, Loïc ULiege; Darchambeau, François ULiege et al

Conference (2016, December 16)

Most seagrasses are rarely consumed directly by herbivore organisms. The "detrital pathway" thus represents a potentially important way of transfer of the seagrasses production to the coastal food webs ... [more ▼]

Most seagrasses are rarely consumed directly by herbivore organisms. The "detrital pathway" thus represents a potentially important way of transfer of the seagrasses production to the coastal food webs. The case of Posidonia oceanica is particularly interesting since up to 90% of its foliar primary production may constitute extensive and highly dynamic exported litter accumulations. Preliminary studies concerning these detritus accumulations suggest that an abundant community of vagile macro invertebrates (size > 500μm) lives inside them. We characterized for the first time this community in an exhaustive way (multi-site, seasonal and multi-year study), we linked the observed density and diversity variations to environmental parameters, but also described the trophic web these invertebrates compose. We sampled an abundant (up to 5000 organisms/m²) community composed of 115 species. We showed that crustaceans were massively dominant, followed by annelids and mollusks, and that one single amphipod species Gammarella fucicola represented from 20 to 85% of the whole sampled community. Observed variations appeared to be mostly linked to litter oxygen water concentration in a very species specific way. Most species were linked to no measured environmental parameter at all, but several dominant species were demonstrated (observation and in situ experimentation) to be linked positively or negatively to litter oxygen concentration. The described food web was composed of more than 3 trophic levels, indicating the presence of a trophic web composed of primary consumers/detritivore species, of omnivore species, but also of first and second order predators, each level occupying a distinct isotopic niche. From a specific point of view, we highlighted several different feeding preferences, with SIAR mixing model runs indicating that some species feed mostly on detrital material, other species feed on a mixture of detrital and algal material, other species feed on both animal and vegetal material and finally predator species feed exclusively on animal material. The fact that P. oceanica detritus constituted a non-negligible food source for some dominant species confirmed the importance of this macrofauna community as a key transfer link of seagrass organic matter from P. oceanica to the coastal food webs. [less ▲]

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See detailFeeding ecology of metamorphic and paedomorphic palmate newts (Lissotriton helveticus) in Larzac
Didaskalou, Emilie; Lejeune, Benjamin ULiege; Lepoint, Gilles ULiege et al

Poster (2016, December 16)

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See detailExploitation of coastal fish communities by harbour porpoises Phocoena phocoena during nursing periods in German Baltic waters.
Pinzone, Marianna ULiege; Michel, Loïc ULiege; Gallus, Anja et al

Conference (2016, December 11)

Baltic sub-populations of harbour porpoises Phocoena phocoena meet in in Southwestern waters in Spring when females reach the coastal areas for calving and nursing. In Autumn they separate again for ... [more ▼]

Baltic sub-populations of harbour porpoises Phocoena phocoena meet in in Southwestern waters in Spring when females reach the coastal areas for calving and nursing. In Autumn they separate again for reproduction : the Belt sea populations westwards in the Kattegat/Skarregat region, the Baltic proper population northwards in the central basin. The increased number of juvenile and newborn strandings along the German Baltic coasts give evidence for a possible existence of local calving grounds in this area. Calving and nursing habitats are the most important areas for management purposes. This project aimed to describe inhabitancy and diet of females and calves along the German Baltic coast, in order to achieve effective conservation measures. Nitrogen, carbon and, for the first time, sulphur stable isotopes (δ13C, δ15N and δ34S) were analysed in coastal species of fish and invertebrates in spring, autumn and winter 2015/2016 and in four different areas, to assess for seasonal and geographical variation of porpoises habitat use. The structure of ecological niches was inferred within and between communities using the SIBER model, and was compared to results from stomach content analysis. N, C and S values of fish and invertebrates strongly varied, seasonally and geographically, as a consequence of environmental factors characteristic of each sampling area. Additionally, each species presented large isotopic variability, suggesting possible intraspecific dietary specialisations. Females δ13C and δ34S signatures integrated both open-waters and coastal feeding, while juveniles presented a more coastal distribution. The absence of difference in δ15N values between age classes confirmed persistence of milk assimilation from the mothers. Niches structures and overlaps and stomach content analysis suggested gobies (Potamoschistus spp and Neogobius spp in particular), crabs and small coastal fish (ex. three-spined stickleback) as the main preys of juveniles. The integration of all three stable isotopes together permitted to well delineate even the highly dynamic food web of the Baltic German waters, confirming the use of sulphur isotopes in marine ecological studies. [less ▲]

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See detailAssessing edge-effects in Posidonia oceanica seagrass meadows: A multidisciplinary approach
Lapeyra, Jon; Abadie, Arnaud; Lejeune, Pierre et al

Conference (2016, December)

Structural boundaries in ecosystems play an important role both in the context of seascape architecture, ecological processes and biodiversity. The Mediterranean Seagrass Posidonia oceanica (L.) Delile is ... [more ▼]

Structural boundaries in ecosystems play an important role both in the context of seascape architecture, ecological processes and biodiversity. The Mediterranean Seagrass Posidonia oceanica (L.) Delile is considered an ecosystem engineer species, forming habitats of great ecological value and providing many ecosystem services. This study aims to (1) determine whether there are differences between seagrass-sand corridors edges and the adjacent continuous meadow, and (2) investigate whether anthropogenic pressures can cause disturbances in the measured parameters along the edges and the meadow. We have developed a multidisciplinary approach combining plant physiology, faunal canopy community studies and seagrass structural parameters characterization. We performed in situ chlorophyll fluorescence measurements using a Pulse Amplitude Modulated (Diving-PAM) fluorometry in order to assess the photosynthetic rate of the shoots. Vagile macrofauna of the leaf stratum was sampled by a hand-towed net, and the major taxonomic groups were sorted, counted, and identified. Meadow’s biometric measurements and the epiphytic biomass were also determined. Regarding edge-meadow matrix, results have shown highest differences on matrix structural parameters such as shoot density and shoot type proportions. Shoot density was found to decrease in edges considerably. We found c.a to 60 % plagiotropic shoots on edges while in continuous meadow orthotropics were predominant (up to 90 %). Howerver vagile-fauna population densities and diversity did not differ significantly among stations studied, neither by sites. Photosynthetic rate and leaf surface values also did not show changes between edges and continuous meadow. However, results did show that plagiotropic shoots had higher photosynthetic rate than orthotropics, and also that epiphyte abundance sorted out to be much higher (up to 54 %) on edges. [less ▲]

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See detailEcoNum, a research unit devoted to marine environment monitoring
Richir, Jonathan ULiege; Batigny, Antoine; Georges, Nadège et al

Conference (2016, October 27)

The monitoring of coastal environments remains a research domain of great interest and concern. Coastal ecosystems are threatened by natural and human-induced stressors and are, as transitional ... [more ▼]

The monitoring of coastal environments remains a research domain of great interest and concern. Coastal ecosystems are threatened by natural and human-induced stressors and are, as transitional environments, particularly sensitive to disturbances. EcoNum first research thematic revolves around hermatypic corals, calcifying organisms, and their adaptation potentials to environmental changes including by using original and patented chemostats. The studied organisms are grown and maintained in artificial mesocosms that simulate environmental conditions of a natural system. This infrastructure allows to perform long-term experiments, giving time to organisms to adapt to the tested conditions (e.g., increased temperature or lowered pH). Longer-term studies have demonstrated that many organisms are more resistant to environmental stressors than previously observed on the short-term. EcoNum also studies coastal plankton abundance and diversity. Plankton is particularly sensitive to physicochemical changes of water bodies. The classification and the enumeration of planktonic organisms require specialized tools in order to analyse time series of multiple samples. EcoNum has developed a software for the semi-automatic classification of planktonic organisms called Zoo/PhytoImage. This software has been used to study a 10-year time series of coastal Mediterranean zooplankton samples. The concomitant analysis of environmental parameters registered at high frequency with specific statistical tools such as the R package pastecs allows to understand the processes governing the changes observed in plankton assemblages. The use and the development of statistical tools in R (e.g., Zoo/Phytoimage, pastecs) is a priority of EcoNum to favour open access knowledge and reproductive sciences. EcoNum research topics also focus on coastal ecotoxicology. Chemicals, including trace elements, remain contaminants of concern, mainly in coastal environments that are the final sink of inland pollution sources. The chemical integrity of coastal ecosystems thus has to be accurately monitored. The partitioning of chemicals between their dissolved, particulate and sedimentary phases does not provide information on their bioavailability. EcoNum thus monitors coastal waters using bioindicator species such as seagrasses, mussels or sand worms. A global map of the contamination of the Mediterranean by trace elements has been drawn using seagrasses has bioindicator species. EcoNum also studies trace element ecology and toxicology. For instance, it has demonstrated the toxicity of copper on the coral Seriatopora hystrix and it's symbiont's photosynthetic processes, or its bioaccumulation and basipetal translocation towards rhizomes in the seagrass Posidonia oceanica as reserve nutrient for subsequent leaf growth. Finally, coastal vegetated systems are potential carbon thinks (or sources) in the global carbon cycle. Therefore, EcoNum studies the primary productivity of seagrass meadows, from the individual to the community, with measuring techniques as diverse as PAM-fluorometry or biomass production determination. To conclude, EcoNum is a research unit devoted to marine environment monitoring. It develops research thematics on major coastal communities such as coral reefs, seagrass beds or plankton assemblages and studies their natural dynamics and the effects of stressors on their global functioning. [less ▲]

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See detailA one year survey of seagrass primary productivity using the diving-PAM technique
Richir, Jonathan ULiege; Abadie, Arnaud; Grosjean, Philippe et al

Poster (2016, October 18)

Marine magnoliophytes are major primary producers in coastal benthic habitats worldwide. They play a crucial role in the global carbon cycle (one of the more efficient blue carbon wells). Hence, it is ... [more ▼]

Marine magnoliophytes are major primary producers in coastal benthic habitats worldwide. They play a crucial role in the global carbon cycle (one of the more efficient blue carbon wells). Hence, it is necessary to characterise the eco-systemic services seagrass meadows provide. Posidonia oceanica (L.) Delile, the main Mediterranean seagrass species, has high foliar and belowground biomass production. Several methods have been used so far to measure its primary production (e.g., using incubation bells, optodes, biomass and elementary content measurements). A less used method relies on chlorophyll fluorescence measurements through the Pulse Amplitude Modulated (PAM) fluorometry method (Diving - PAM). In the framework of the STARECAPMED project, this study aimed to determine weekly to bimonthly over a one-year period the photosynthetic responses (Yield, relative Electron Transfer Rate, Rapid Light Curve) of P. oceanica. The survey was performed at 10m depth in a pristine meadow (Calvi, Corsica, France). To obtain reliable and comparable data, the protocol was standardized: measurements were performed on the convex middle part of the third leaf, at zenith, during shiny and calm weather days. Results showed that the plant displayed a well-marked seasonality. The mean ETR (μmol e- m-2 s-1 ) of the plant ranged from 2.17 in winter to 21.9 in summer and was linearly correlated throughout the year with the in situ irradiance (PAR irradiance taken perpendicularly to the surface, in the average leaf orientation). The ETR plateaus of the RLCs, ranging from 10.9 to 35.0, and their corresponding maximum PAR intensities evolved similarly. These results demonstrated both the adaptation and the seasonal plasticity of the meadow’s photosynthetic system. Overall the non-destructive PAM technique is a powerful and cost-effective tool to assess the primary productivity of seagrass meadows where other techniques (e.g. optodes) cannot be used and when direct sampling (e.g. biomass measurements) is not allowed. [less ▲]

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See detailDiversity, dynamics and trophic ecology of animal communities associated to Posidonia oceanica (L.) Delile macrophytodetrital accumulation: synthesis of a ten year study
Lepoint, Gilles ULiege; Borges, Alberto ULiege; Champenois, Willy ULiege et al

Poster (2016, October 17)

In the Mediterranean, Neptune grass Posidonia oceanica, produces a huge quantity of detrital biomass. These macrophytodetritus may accumulate in shallow waters, forming litter accumulations colonised by ... [more ▼]

In the Mediterranean, Neptune grass Posidonia oceanica, produces a huge quantity of detrital biomass. These macrophytodetritus may accumulate in shallow waters, forming litter accumulations colonised by abundant, yet understudied, animal communities. These accumulations are especially foraged by juvenile and adult fishes. Here, we aim to synthesize results obtained over the last ten years regarding diversity, dynamics and trophic ecology of associated meio- and macrofauna. Accumulations are found throughout the year but important seasonal and short-term variability in composition, quantity and physico-chemical parameters inside the accumulation is observed. Accumulations are dominated by respiration (litter degradation), however, primary production occurs at exposed surfaces (epiphytic production). Meio- and macrofauna have distinct traits in comparison to adjacent habitats (seagrass meadows or epilithic algae communities). A physico-chemical gradient occurs inside accumulations which partially defines assemblage composition and distribution. Meiofauna, in particular harpacticoid copepods, is diverse, abundant and composed of species from seagrass meadows, water column and sediment. In contrast, macrofaunal assemblages are simplified compared to the ones occurring in the seagrass meadows and are dominated by amphipods. Litter accumulations display a lower macrofaunal diversity than do seagrass meadows, but a higher abundance and animal biomass. Meio- and macrofauna show a high trophic diversity, dominated by ingestion and assimilation of epiphytes (macroalgae and, probably, detrivorous microbiota). Moreover, direct or indirect assimilation of carbon originating from seagrass detritus is demonstrated for many species. Although diverse trophic niches were observed, the assemblage showed a simplified trophic web structure compared to the seagrass meadows. Detritivorous organisms dominate this assemblage and are more abundant in the litter than in the living meadows. Consequently, according to its abundance and the fact it consumes directly and indirectly seagrass material, fauna associated to litter accumulation may play a significant role in the degradation and transfer to higher trophic level of detrital seagrass carbon. [less ▲]

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See detailInvestigating the potential of Cymodocea nodosa (Ucria) Ascherson as a coastal carbon sink coupling marine habitat cartographies and in situ nondestructive sampling
Abadie, Arnaud ULiege; Richir, Jonathan ULiege; Pieraccini, Riccardo ULiege et al

Poster (2016, October)

Seagrass meadows are major carbon sinks, trapping about 10% of the total CO2 sequestrated in the oceans. In the Mediterranean, a major focus has been made on the climax species Posidonia oceanica (L ... [more ▼]

Seagrass meadows are major carbon sinks, trapping about 10% of the total CO2 sequestrated in the oceans. In the Mediterranean, a major focus has been made on the climax species Posidonia oceanica (L.) Delile, while other species remained little studied. In the framework of the STARECAPMED project, we thus chose to study Cymodocea nodosa (Ucria) Ascherson, a pioneer species with a rapid turnover and an expected high stocking capacity. Furthermore, the area covered by that species has been largely underestimated. In order to fill these two knowledge gaps, we first mapped all seagrass habitats within a Mediterranean bay (Calvi, Corsica, France) using side scan images, aerial photographs and ground truths. This cartography was followed by seasonal in situ density measurements and non-destructive shoot sampling (leaf cutting). Samplings were performed at different depths (5 to 23 m depth) in 6 contrasted stations (small patchy meadows to continuous beds) in order to cover all the existing facies of the bay. Elementary contents (carbon, nitrogen and stable isotope ratios) were measured in laboratory. This first work shows that C. nodosa meadows in Calvi Bay cover an area of 0.498 km2. Carbon stocks of the leaves reached 0.25 tons in winter and 2.72 tons in summer. Their nitrogen contents showed a marked seasonality with a maximum value of 0.020 mgN.m-2 in July and a minimum value of 0.005 mgN.m-2 in March. Some modifications in the trophic conditions of the water column at several stations were put in an obvious through the N stable isotopes values, mostly during the summer period. The actual underestimation of the area covered by that species in Calvi Bay has been properly mapped thanks to side scan sonar techniques revealing, together with elementary content analysis, its importance in the carbon balance of coastal areas. [less ▲]

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See detailPhenology of farmed seaweed Kappaphycus alvarezii infestation by the parasitic epiphyte Polysiphonia sp. in Madagascar
Tsiresy, Gaëtan; Preux, Jérémy; Lavitra, Thierry et al

in Journal of Applied Phycology (2016), 28(5), 29032914

epiphytic filamentous algae (EFA) disease has appeared in many regions of Madagascar. This infestation has dramatic consequences for local farmers as it alters drastically farmed algal growth and has ... [more ▼]

epiphytic filamentous algae (EFA) disease has appeared in many regions of Madagascar. This infestation has dramatic consequences for local farmers as it alters drastically farmed algal growth and has caused farming activity to collapse in many places. The present study characterizes the structure and ultrastructure of the stages observed in the life cycle of Polysiphonia sp. and gives the results of a monitoring of 18 months made in three Kappaphycus alvarezii farming sites in the southwest of Madagascar. Transmission electron microscopy (TEM) was used to analyze the ultrastructure of the cortex in infested K. alvarezii. Five stages have been observed in the life cycle of Polysiphonia sp.: the infesting stage that is a small dark spot observed at the surface of K. alvarezii, the male gametophyte, the female gametophyte, the tetrasporocysts, and the undifferentiated stage where individuals show normal thalli without sexual differentiation. EFA infestation was never recorded in Sarodrano, but often in the two other monitored villages (Lambohara, Tampolove). Prevalence of infestation varied from 40 to 100 % and the rates of infestation from 42 to 78 epiphytes cm−2. Prevalence of infestation showed significant seasonal variation and a between-sites variation; the rates of infestation were not significantly different between sites and did not vary with the period. The ways of infestation between K. alvarezii individuals in an infested field and from infested to healthy fields are discussed at the light of the present results. [less ▲]

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See detailAxIOM: Amphipod crustaceans from insular Posidonia oceanica seagrass meadows
Michel, Loïc ULiege; Sturaro, Nicolas ULiege; Heughebaert, André et al

in Biodiversity Data Journal (2016), 4

Background The Neptune grass, Posidonia oceanica (L.) Delile, 1813, is the most widespread seagrass of the Mediterranean Sea. This foundation species forms large meadows that, through habitat and trophic ... [more ▼]

Background The Neptune grass, Posidonia oceanica (L.) Delile, 1813, is the most widespread seagrass of the Mediterranean Sea. This foundation species forms large meadows that, through habitat and trophic services, act as biodiversity hotspots. In Neptune grass meadows, amphipod crustaceans are one of the dominant groups of vagile invertebrates, forming an abundant and diverse taxocenosis. They are key ecological components of the complex, pivotal, yet critically endangered Neptune grass ecosystems. Nevertheless, comprehensive qualitative and quantitative data about amphipod fauna found in Mediterranean Neptune grass meadows remain scarce, especially in insular locations. New information Here, we provide in-depth metadata about AxIOM, a sample-based dataset published on the GBIF portal. AxIOM is based on an extensive and spatially hierarchized sampling design with multiple years, seasons, day periods, and methods. Samples were taken along the coasts of Calvi Bay (Corsica, France) and of the Tavolara-Punta Coda Cavallo Marine Protected Area (Sardinia, Italy). In total, AxIOM contains 187 samples documenting occurrence (1775 records) and abundance (10720 specimens) of amphipod crustaceans belonging to 72 species spanning 29 families. The dataset is available at http://ipt.biodiversity.be/resource?r=axiom. [less ▲]

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See detailFeeding ecology of Southern Ocean seastars inferred from stable isotopes ratios
Le Bourg, Baptiste ULiege; Blanchard, Alice; Danis, Bruno et al

Poster (2016, September 05)

The Southern Ocean is currently subjected to strong and contrasted impacts of climate change. The Western Antarctic Peninsula is one of the most rapidly warming regions of the world, resulting in sea ice ... [more ▼]

The Southern Ocean is currently subjected to strong and contrasted impacts of climate change. The Western Antarctic Peninsula is one of the most rapidly warming regions of the world, resulting in sea ice cover decreases. Increasing seawater temperature and sea ice cover reduction in Western Antarctic Peninsula and associated regions will likely impact food web functioning through temperature-related changes in consumer physiology, modifications of benthic community structure (e.g. expansion of exogenous species such as predatory crabs), modifications of benthic-pelagic coupling intensity or disruption of benthic production. Asteroids (Echinoderms) are an important group of southern benthos. This group also has a great trophic variability and is potentially more resistant than other organisms to temperature changes (Peck et al. 2008). Consequently, they will be likely impacted by modifications in food webs functioning rather by direct warming and investigating their trophic ecology is necessary to infer how climate change will impact them. In this context, the aim of this study is to use stable isotopes ratios of C, N and S to infer sea stars trophic ecology. 16 species of sea stars spanning 10 different families sampled in multiple and contrasted habitats across Subantarctic (South Georgia, South Sandwich Islands, Falkland Islands) and Antarctic (South Shetland Islands, South Orkney Islands, Western Antarctic Peninsula) locations. In total, tegument samples from 213 specimens was analysed. Diversity and plasticity of asteroid diet along Southern Ocean coasts were explored through isotopic niche parametrisation (e.g. niche width and overlap between species and/or populations; Jackson et al. 2011). The data will also be used in a larger scale research project on the trophic ecology of Antarctic sea stars. This project will notably compare trophic resources supporting asteroid communities in Western Antarctic Peninsula, where sea ice cover is decreasing, and in Terre Adélie, where sea ice cover is increasing (Parkinson & Cavalieri 2012). Ultimately, this project will help understanding which ecological processes determine how an animal group copes with environmental modifications linked to climate change. [less ▲]

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