%0 Journal Article %J Polar Biology %D 2022 %T Passive acoustics suggest two different feeding mechanisms in the Atlantic walrus (Odobenus rosmarus rosmarus) %A Jézéquel, Youenn %A Mathias, Delphine %A Frédéric Olivier %A Amice, Erwan %A Chauvaud, Sylvain %A Jolivet, Aurélie %A Bonnel, Julien %A Sejr, Mikael K. %A Chauvaud, Laurent %K Bioacoustics %K bivalves %K Feeding Behavior %K Marine mammal %K Young Sound fjord %X The vocal repertoire of walruses has been widely described in the bioacoustic literature. These marine mammals produce several distinct types of vocalizations for intraspecific communication during the breeding season. In this study, we provide the first evidence of walrus-generated sounds during foraging dives when they feed on bivalves. We recorded two types of sounds that we associated to different feeding mechanisms. The first sound type was brief and low in frequency that we relate to the suction of soft parts from the bivalves’ shells through the use of walrus powerful tongues, which is the common feeding behavior reported in the walrus literature. We also recorded a second sound type composed of multiple broadband pulse trains. We hypothesize the latter were associated with bivalve shell cracking by walruses, which would represent a new feeding mechanism in the walrus literature. This new feeding mechanism is either related to bivalves’ ecology or to walruses removing the sediment when searching for food. During this study, we observed bivalves lying on the seafloor instead of being buried in the sediment in walrus feeding areas while scuba diving. As a result, walruses cannot use suction to feed on soft body part of bivalves and have to use another strategy, mastication. Our findings provide a first step towards using passive acoustics to quantify walrus behavior and feeding ecology. %B Polar Biology %8 Sep-06-2023 %G eng %U https://link.springer.com/10.1007/s00300-022-03055-y %! Polar Biol %R 10.1007/s00300-022-03055-y %0 Journal Article %J Ecosphere %D 2022 %T Pull the trigger: interplay between benthic and pelagic cues driving the early recruitment of a natural bivalve assemblage %A Androuin, Thibault %A Barbier, Pierrick %A Foret, Martin %A Tarik Meziane %A Thomas, Mathilde %A Archambault, Philippe %A Winkler, Gesche %A Tremblay, Rejean %A Frédéric Olivier %K bacteria %K bivalves %K Chausey Archipelago %K early larval recruitment %K fatty acids %K picoeucaryotes %K trophic settlement trigger %X Larval settlement and recruitment are crucial phases in the benthic-pelagic life cycle of marine benthic invertebrates that controls population dynamic and habitat connectivity. Our study investigated potential triggers driving the settlement of bivalve larvae in a highly dynamic intertidal coarse sand habitat. The early recruitment rate of five dominant bivalve families and abiotic conditions, particulate (<20 µm) organic matter and sediment organic matter, were monitored from May to October 2014. Pelagic particulate organic matter (<20 µm) was dominated by picoplankton throughout the sampling period, with a substantial diatom bloom in spring. Sediment was characterized by fresh organic matter in spring, as suggested by the dominant contribution of polyunsaturated fatty acids, and by a higher proportion of bacterial fatty acid markers during late summer. Different dynamics were also observed in early bivalve recruitment rates, with four different patterns observed over the sampling period. Multiple regression analysis on selected bivalve families showed species-specific responses to trophic settlement triggers. Indeed, the larva recruitment rate of Mytilidae paralleled pelagic concentration of picoeucaryotes, with the peak early recruitment rate occurring in spring. Surprisingly, the early recruitment rate of Mactridae larvae showed a significant relation to bacterial concentration in the surficial sediment at the end of summer. While the Mytilidae results in such a eutrophic system confirmed those of a previous study in oligotrophic lagoons, therefore supporting the trophic settlement trigger hypothesis, more work is needed to understand the potential role of bacteria in the early recruitment of Mactridae. These results highlight for the first-time inter-specific differences in trophic cues that potentially trigger primary settlement in natural bivalve assemblages. %B Ecosphere %V 13 %8 Jan-01-2022 %G eng %U https://onlinelibrary.wiley.com/toc/21508925/13/1 %N 1 %! Ecosphere %R 10.1002/ecs2.v13.110.1002/ecs2.3672 %0 Journal Article %J Marine Pollution Bulletin %D 2020 %T Realistic environmental exposure to microplastics does not induce biological effects in the Pacific oyster Crassostrea gigas %A Revel, Messika %A Châtel, Amélie %A Perrein-Ettajani, Hanane %A Bruneau, Mélanie %A Akcha, Farida %A Sussarellu, Rossana %A Rouxel, Julien %A Katherine Costil %A Decottignies, Priscilla %A Cognie, Bruno %A Lagarde, Fabienne %A Mouneyrac, Catherine %K biodeposits %K biomarkers %K bivalves %K Crassostrea gigas %K microplastics %X The aim of the present study was to evaluate the presence and potential toxic effects of plastic fragments(< 400μm) of polyethylene and polypropylene on the Pacific oysterCrassostrea gigas.Oysters were exposed toenvironmentally relevant concentrations (0, 0.008, 10, 100μg of particles/L) during 10 days, followed by adepuration period of 10 days in clean seawater. Effects of microplastics were evaluated on the clearance rate oforganisms, tissue alteration, antioxidant defense, immune alteration and DNA damage. Detection and quanti-fication of microplastics in oyster's tissues (digestive gland, gills and other tissues) and biodeposits using infraredmicroscopy were also conducted. Microplastics were detected in oyster's biodeposits following exposure to alltested concentrations: 0.003, 0.006 and 0.05 particles/mg of biodeposits in oysters exposed to 0.008, 10 and100μg of particles/L, respectively. No significant modulation of biological markers was measured in organismsexposed to microplastics in environmentally relevant conditions. %B Marine Pollution Bulletin %V 150 %P 110627 %8 Jan-01-2020 %G eng %U https://linkinghub.elsevier.com/retrieve/pii/S0025326X19307751 %! Marine Pollution Bulletin %R 10.1016/j.marpolbul.2019.110627