Feeding ecology of Southern Ocean seastars inferred from stable isotopes ratios

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

Trophic ecology of Southern Ocean sea stars inferred from stable isotopes ratios of C and N

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

Complete distribution of the genus Laevilitorina (Littorinimorpha: Littorinidae) in the Southern Hemisphere: remarks and natural history

Littorinid snails are present in most coastal areas globally, playing a significant role in the ecology of intertidal communities. Laevilitorina is a marine gastropod genus distributed exclusively in the Southern Hemisphere, with 21 species reported from South America, the sub-Antarctic islands, Antarctica, New Zealand, Australia and Tasmania. Here, an updated database of 21 species generated from a combination of sources is presented: 1) new field sampling data; 2) published records; 3) the Global Biodiversity Information Facility (GBIF) and The Atlas of Living Australia (ALA), to provide a comprehensive description of the known geographic distribution of the genus and detailed occurrences for each of the 21 species. The database includes 813 records (occurrences), 53 from field sampling, 174 from the literature, 128 from GBIF, and 458 from ALA. West Antarctica had the highest species richness (8 species), followed by sub-Antarctic islands of New Zealand (4 species) and the south-east shelf of Australia (4 species). The provinces of Magellan, New Zealand South Island, and sub-Antarctic Islands of the Indian Ocean include two species each. This study specifically highlights reports of L. pygmaea and L. venusta, species that have been almost unrecorded since their description. Recent advances in molecular studies of L. caliginosa showed that this species does not correspond to a widely distributed taxon, but to multiple divergent lineages distributed throughout the Southern Ocean. Ongoing molecular and taxonomic studies are necessary for a better understanding of the diversity and biogeography of this genus

Différenciation génétique et morphologique de Dissodactylus primitivus, crabe ectoparasite de deux échinides sympatriques, Meoma ventricosa et Plagiobrissus grandis -- Biologie des organismes et écologie

info:eu-repo/semantics/nonPublishe

Molecular ecology of a host-parasite relationship in an insular context ectoparasitic crabs of spantagoid sea-urchins in the Caribbean Sea

Comparer les structures génétiques des populations de deux espèces permet d’évaluer les facteurs environnementaux et les traits d’histoire de vie qui façonnent la dispersion des individus. Dans le cas d’un couple hôte-parasite, cette approche permet aussi de mettre en évidence l’adaptation locale de ces espèces. Le modèle étudié ici est le crabe ectoparasite Dissodactylus primitivus et son oursin-hôte Meoma ventricosa, deux espèces endémiques des Caraïbes et des côtes américaines voisines. Plusieurs outils moléculaires ont été utilisés à savoir des microsatellites ainsi qu’un marqueur mitochondrial (cytochrome oxydase I). De plus, des analyses morphométriques (analyse de contour) ont également été réalisées.En étudiant des populations le long de l’arc antillais et de la côte panaméenne, ce travail a mis en évidence que la structure génétique des populations du parasite D. primitivus diffère fortement de celle de son hôte M. ventricosa. En effet, alors que les populations du parasite présentent une différenciation au sein de cette région, celles de l’hôte sont génétiquement homogènes. Ce contraste peut être expliqué par des caractères biologiques et écologiques propres à chacune des deux espèces (fécondité, habilité à la nage, disponibilité de l’habitat) et suggère des potentialités d’adaptation locale distinctes selon l’espèce considérée. La distance géographique semble être un facteur important dans la structuration génétique des populations du crabe parasite mais la courantologie actuelle ou encore des évènements passés (glaciations) jouent également un rôle. A l’échelle locale d’une même île, les crabes ne présentent pas de différenciations génétique et morphologique entre des sites côtiers distincts. En outre, à cette même échelle (lagon jamaïcain), nous avons pu montrer que des crabes issus d’hôtes d’espèces différentes ne sont pas différenciés génétiquement. Cette absence de différenciation est liée au moins en partie à la mobilité des crabes adultes. Par des analyses de paternité, nous avons souligné cette mobilité et démontré non seulement que le mode de reproduction du crabe correspond à de la polygamie mais aussi que des accouplements pouvaient avoir lieu entre des crabes issus d’espèces d’hôtes distinctes.Comparing the population genetic structures of two species documents on the environmental factors and life history traits that shape the dispersal of the individuals. For host-parasite couple, this approach also permits to predict local adaptation of these species. The investigated species in this work are the ectoparasitic crab Dissodactylus primitivus and its sea urchin host Meoma ventricosa, both species being endemic to the Caribbean and neighboring American coasts. Several molecular markers were used, namely microsatellites and cytochrome oxidase I (mitochondrial). Moreover, morphometric analyses (shape) were also done. By studying populations across the Antilles arc and along the Panamanian coast, this work have shown that the genetic structure of the crab populations deeply differ from that of its host. Indeed, while the parasite populations are differentiated within this region, host populations are genetically homogeneous. This contrast can be explained by biological and ecological features (fecundity, swimming capacities, suitability of habitat) that are species specific and it suggests a distinct potentiality of local adaptation between host and parasite. Geographical distance seems to be a key parameter in the observed patterns but marine currents and historical events (glaciations) also play a role. At the local scale of a single island, crabs lack genetic and morphological differentiations when sites are compared along the coast. In addition, at the same scale (Jamaican lagoon), we demonstrated that crabs from different host species are not genetically differentiated. This lack of differentiation is at least partly explained by the mobility of adult crabs. Through paternity analyses, we underlined this mobility and we demonstrated that the crabs have a polygamous behavior but also that mating can occur among crabs from different host species

Ecologie moléculaire d'une relation hôte - parasite en contexte insulaire marin. Crabes parasites des oursins spatangues en Mer des Caraïbes

Comparing the population genetic structures of two species documents on the environmental factors and life history traits that shape the dispersal of the individuals. For host-parasite couple, this approach also permits to predict local adaptation of these species. The investigated species in this work are the ectoparasitic crab Dissodactylus primitivus and its sea urchin host Meoma ventricosa, both species being endemic to the Caribbean and neighboring American coasts. Several molecular markers were used, namely microsatellites and cytochrome oxidase I (mitochondrial). Moreover, morphometric analyses (shape) were also done. By studying populations across the Antilles arc and along the Panamanian coast, this work have shown that the genetic structure of the crab populations deeply differ from that of its host. Indeed, while the parasite populations are differentiated within this region, host populations are genetically homogeneous. This contrast can be explained by biological and ecological features (fecundity, swimming capacities, suitability of habitat) that are species specific and it suggests a distinct potentiality of local adaptation between host and parasite. Geographical distance seems to be a key parameter in the observed patterns but marine currents and historical events (glaciations) also play a role. At the local scale of a single island, crabs lack genetic and morphological differentiations when sites are compared along the coast. In addition, at the same scale (Jamaican lagoon), we demonstrated that crabs from different host species are not genetically differentiated. This lack of differentiation is at least partly explained by the mobility of adult crabs. Through paternity analyses, we underlined this mobility and we demonstrated that the crabs have a polygamous behavior but also that mating can occur among crabs from different host species.Comparer les structures génétiques des populations de deux espèces permet d’évaluer les facteurs environnementaux et les traits d’histoire de vie qui façonnent la dispersion des individus. Dans le cas d’un couple hôte-parasite, cette approche permet aussi de mettre en évidence l’adaptation locale de ces espèces. Le modèle étudié ici est le crabe ectoparasite Dissodactylus primitivus et son oursin-hôte Meoma ventricosa, deux espèces endémiques des Caraïbes et des côtes américaines voisines. Plusieurs outils moléculaires ont été utilisés à savoir des microsatellites ainsi qu’un marqueur mitochondrial (cytochrome oxydase I). De plus, des analyses morphométriques (analyse de contour) ont également été réalisées.En étudiant des populations le long de l’arc antillais et de la côte panaméenne, ce travail a mis en évidence que la structure génétique des populations du parasite D. primitivus diffère fortement de celle de son hôte M. ventricosa. En effet, alors que les populations du parasite présentent une différenciation au sein de cette région, celles de l’hôte sont génétiquement homogènes. Ce contraste peut être expliqué par des caractères biologiques et écologiques propres à chacune des deux espèces (fécondité, habilité à la nage, disponibilité de l’habitat) et suggère des potentialités d’adaptation locale distinctes selon l’espèce considérée. La distance géographique semble être un facteur important dans la structuration génétique des populations du crabe parasite mais la courantologie actuelle ou encore des évènements passés (glaciations) jouent également un rôle. A l’échelle locale d’une même île, les crabes ne présentent pas de différenciations génétique et morphologique entre des sites côtiers distincts. En outre, à cette même échelle (lagon jamaïcain), nous avons pu montrer que des crabes issus d’hôtes d’espèces différentes ne sont pas différenciés génétiquement. Cette absence de différenciation est liée au moins en partie à la mobilité des crabes adultes. Par des analyses de paternité, nous avons souligné cette mobilité et démontré non seulement que le mode de reproduction du crabe correspond à de la polygamie mais aussi que des accouplements pouvaient avoir lieu entre des crabes issus d’espèces d’hôtes distinctes

Data from: Dwarf brooder versus giant broadcaster: combining genetic and reproductive data to unravel cryptic diversity in an Antarctic brittle star

Poecilogony, or multiple developmental modes in a single species, is exceedingly rare. Several species described as poecilogenous were later demonstrated to be multiple (cryptic) species with a single developmental mode. The Southern Ocean is known to harbor a high proportion of brooders (Thorson's Rule) but with an increasing number of counter examples over recent years. Here we evaluated poecilogony versus crypticism in the brittle star Astrotoma agassizii across the Southern Ocean. This species was initially described from South America as a brooder before some pelagic stages were identified in Antarctica. Reproductive and mitochondrial data were combined to unravel geographic and genetic variation of developmental modes. Our results indicate that A. agassizii is composed of seven well supported and deeply divergent clades (I: Antarctica and South Georgia; II: South Georgia and Subantarctic locations including Kerguelen, Patagonian shelf, and New Zealand; III-VI-VII: Patagonian shelf, IV-V: South Georgia). Two of these clades demonstrated strong size dimorphism when in sympatry and can be linked to differing developmental modes (Clade V: dwarf brooder versus Clade I: giant broadcaster). Based on their restricted geographic distributions and on previous studies, it is likely that Clades III-VI-VII are brooders. Clade II is composed of different morphological species, A. agassizii and A. drachi, the latter originally used as the outgroup. By integrating morphology, reproductive and molecular data we conclude that the variation identified in A. agassizii is best described as crypticism rather than poecilogony

Characterization of eight microsatellite loci for the sea urchin Meoma ventricosa (Spatangoida, Brissidae) through Next Generation Sequencing

Eight microsatellite loci were characterized for Meoma ventricosa (Lamarck, 1816), a burrowing sea urchin that can be afflicted by a bacterial disease causing localized mass mortality. For the analyzed population (29 individuals from St. Croix, US Virgin Islands), we observed 8.125 mean number of alleles, 0.640 mean observed heterozygosity (Ho) and 0.747 mean expected heterozygosity (He). Two loci showed significant deviations from Hardy-Weinberg equilibrium. Overall, the described loci were characterized by a moderately highlevel of polymorphism suggesting that these markers are useful for a population genetic studyin the Caribbean Sea.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Data from: Dwarf brooder versus giant broadcaster: combining genetic and reproductive data to unravel cryptic diversity in an Antarctic brittle star

Poecilogony, or multiple developmental modes in a single species, is exceedingly rare. Several species described as poecilogenous were later demonstrated to be multiple (cryptic) species with a single developmental mode. The Southern Ocean is known to harbor a high proportion of brooders (Thorson's Rule) but with an increasing number of counter examples over recent years. Here we evaluated poecilogony versus crypticism in the brittle star Astrotoma agassizii across the Southern Ocean. This species was initially described from South America as a brooder before some pelagic stages were identified in Antarctica. Reproductive and mitochondrial data were combined to unravel geographic and genetic variation of developmental modes. Our results indicate that A. agassizii is composed of seven well supported and deeply divergent clades (I: Antarctica and South Georgia; II: South Georgia and Subantarctic locations including Kerguelen, Patagonian shelf, and New Zealand; III-VI-VII: Patagonian shelf, IV-V: South Georgia). Two of these clades demonstrated strong size dimorphism when in sympatry and can be linked to differing developmental modes (Clade V: dwarf brooder versus Clade I: giant broadcaster). Based on their restricted geographic distributions and on previous studies, it is likely that Clades III-VI-VII are brooders. Clade II is composed of different morphological species, A. agassizii and A. drachi, the latter originally used as the outgroup. By integrating morphology, reproductive and molecular data we conclude that the variation identified in A. agassizii is best described as crypticism rather than poecilogony