@article {9472, title = {Recruitment dynamics of Hiatella arctica within a high Arctic site (Young Sound Fjord, NE Greenland)}, journal = {Polar Biology}, volume = {46}, year = {2023}, month = {Jan-12-2023}, pages = {1275 - 1286}, abstract = {Recruitment dynamics including what determines the success or failure of Arctic benthic invertebrates are poorly known despite their important role for population dynamics. The main objective of this study was to assess the potential influence of extreme physical constraints related to freshwater discharge on the recruitment of a dominant bivalve Hiatella arctica within a High Arctic fjord (Young Sound, NE Greenland). We collected young recruits over several sampling periods from 2016 to 2018 at two contrasting sites (inner vs. middle fjord) for 5-weeks to 12-months and measured their abundance, size at metamorphosis and lipid class composition. Young stages of H. arctica settled from June to the end of October, when trophic conditions are optimal. We hypothesize that growth stops during winter due to poor trophic conditions. Data suggest that abundance of recruits, their total lipid concentration and composition of lipid classes are similar at both sites. However, size classes were different with six separate cohorts detected at one station and one at the inner station, which may be attributed to discrete spawning events and possible secondary migration. Based on an assessment of their potential age, we hypothesize that spat batches recruiting earlier in the summer exhibit better growth performance probably related to better food quality and quantity.}, keywords = {Arctic, Bivalve recruitment, Lipids classes, prodissoconch II}, issn = {0722-4060}, doi = {10.1007/s00300-023-03201-0}, url = {https://link.springer.com/10.1007/s00300-023-03201-0}, author = {Veillard, Delphine and Tremblay, Rejean and Sejr, Mikael K. and Chauvaud, Laurent and Cam, Emmanuelle and Olivier, Fr{\'e}d{\'e}ric} } @article {9473, title = {Seasonal lipid dynamics of four Arctic bivalves: Implications for their physiological capacities to cope with future changes in coastal ecosystemsAbstract}, journal = {Ecology and Evolution}, volume = {13}, year = {2023}, month = {Jan-11-2023}, abstract = {The Arctic is exposed to unprecedented warming, at least three times higher than the global average, which induces significant melting of the cryosphere. Freshwater inputs from melting glaciers will subsequently affect coastal primary production and organic matter quality. However, due to a lack of basic knowledge on the physiology of Arctic organisms, it remains difficult to understand how these future trophic changes will threaten the long-term survival of benthic species in coastal habitats. This study aimed to gain new insights into the seasonal lipid dynamics of four dominant benthic bivalves (Astarte moerchi, Hiatella arctica, Musculus discors, and Mya truncata) collected before and after sea ice break-up in a high-Arctic fjord (Young Sound, NE Greenland). Total lipid content and fatty acid composition of digestive gland neutral lipids were analyzed to assess bivalve energy reserves while the fatty acid composition of gill polar lipids was determined as a biochemical indicator of interspecies variations in metabolic activity and temperature acclimation. Results showed a decrease in lipid reserves between May and August, suggesting that bivalves have only limited access to fresh organic matter until sea ice break-up. The lack of seasonal variation in the fatty acid composition of neutral lipids, especially essential ω3 fatty acids, indicates that no fatty acid transfer from the digestive glands to the gonads occurs between May and August, and therefore, no reproductive investment takes place during this period. Large interspecies differences in gill fatty acid composition were observed, which appear to be related to differences in species life span and metabolic strategies. Such differences in gill fatty acid composition of polar lipids, which generally influence metabolic rates and energy needs, may imply that not all benthic species will be equally sensitive to future changes in primary production and organic matter quality in Arctic coastal habitats.}, keywords = {Arctic coastal ecosystems, Bivalve, Climate Change, energy reserves, fatty acids, homeoviscous adaptation, meltwater inputs, metabolic rate depression}, issn = {2045-7758}, doi = {10.1002/ece3.v13.1110.1002/ece3.10691}, url = {https://onlinelibrary.wiley.com/toc/20457758/13/11}, author = {Bridier, Guillaume and Olivier, Fr{\'e}d{\'e}ric and Grall, Jacques and Chauvaud, Laurent and Sejr, Mikael K. and Tremblay, Rejean} } @article {8739, title = {Passive acoustics suggest two different feeding mechanisms in the Atlantic walrus (Odobenus rosmarus rosmarus)}, journal = {Polar Biology}, year = {2022}, month = {Sep-06-2023}, abstract = {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{\textquoteright} 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{\textquoteright} 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.}, keywords = {Bioacoustics, bivalves, Feeding Behavior, Marine mammal, Young Sound fjord}, issn = {0722-4060}, doi = {10.1007/s00300-022-03055-y}, url = {https://link.springer.com/10.1007/s00300-022-03055-y}, author = {J{\'e}z{\'e}quel, Youenn and Mathias, Delphine and Fr{\'e}d{\'e}ric Olivier and Amice, Erwan and Chauvaud, Sylvain and Jolivet, Aur{\'e}lie and Bonnel, Julien and Sejr, Mikael K. and Chauvaud, Laurent} } @article {7804, title = {Food source diversity, trophic plasticity, and omnivory enhance the stability of a shallow benthic food web from a high-Arctic fjord exposed to freshwater inputs}, journal = {Limnology and Oceanography}, volume = {66}, year = {2021}, month = {01/2021}, pages = {S259-S272}, type = {Research}, abstract = {
Under climate change, many Arctic coastal ecosystems receive increasing amounts of freshwater, with ecological consequences that remain poorly understood. In this study, we investigated how freshwater inputs may affect the small-scale structure of benthic food webs in a low-production high-Arctic fjord (Young Sound, NE Greenland). We seasonally sampled benthic invertebrates from two stations receiving contrasting freshwater inputs: an inner station exposed to turbid and nutrient-depleted freshwater flows and an outer station exposed to lower terrestrial influences. Benthic food web structure was described using a stable isotope approach (δ13C and δ15N), Bayesian models, and community-wide metrics. The results revealed the spatially and temporally homogeneous structure of the benthic food web, characterized by high trophic diversity (i.e., a wide community isotopic niche). Such temporal stability and spatial homogeneity mirrors the high degree of trophic plasticity and omnivory of benthic consumers that allows the maintenance of several carbon pathways through the food web despite different food availability. Furthermore, potential large inputs of shelf organic matter together with local benthic primary production (i.e., macroalgae and presumably microphytobenthos) may considerably increase the stability of the benthic food web by providing alternative food sources to locally runoff-impacted pelagic primary production. Future studies should assess beyond which threshold limit a larger increase in freshwater inputs might cancel out these stability factors and lead to marked changes in Arctic benthic ecosystems.
}, doi = {https://doi.org/10.1002/lno.11688}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.1002/lno.11688}, author = {Bridier, Guillaume and Fr{\'e}d{\'e}ric Olivier and Chauvaud, Laurent and Sejr, Mikael K. and Grall, Jacques} } @article {5830, title = {Coastal waters freshening and extreme seasonality affect organic matter sources, quality, and transfers in a High Arctic fjord (Young Sound, Greenland)}, journal = {Marine Ecology Progress Series}, volume = {610}, year = {2019}, pages = {15-31}, abstract = {

Arctic benthic ecosystems are expected to experience strong modifications in the dynamics of primary producers and/or benthic-pelagic coupling under climate change. However, lack of knowledge about the influence of physical constraints (e.g. ice-melting associated gradients) on organic matter sources, quality, and transfers in systems such as fjords can impede predictions of the evolution of benthic-pelagic coupling in response to global warming. Here, sources and quality of particulate organic matter (POM) and sedimentary organic matter (SOM) were characterized along an inner-outer gradient in a High Artic fjord (Young Sound, NE Greenland) exposed to extreme seasonal and physical constraints (ice-melting associated gradients). The influence of the seasonal variability of food sources on 2 dominant filter-feeding bivalves (Astarte moerchi and Mya truncata) was also investigated. Results revealed the critical impact of long sea ice/snow cover conditions prevailing in Young Sound corresponding to a period of extremely poor and degraded POM and SOM. Freshwater inputs had a very local impact during summer, with relatively more degraded POM at the surface compared to bottom waters that were less nutritionally depleted but more heterogeneous among the sampled stations. Terrestrial inputs contributed to the SOM composition but showed a large variability along the fjord. Finally, diet analyses underlined the contrasted nutritional conditions, showing much higher lipid reserves in A. moerchi than in M. truncata during winter. Under a scenario with increased freshwater input, such results suggest a decline in organic matter quality and production in Young Sound, with subsequent impacts on benthic food webs.

}, doi = {10.3354/meps12857}, url = {https://www.int-res.com/abstracts/meps/v610/p15-31/}, author = {Bridier, Guillaume and Tarik Meziane and Grall, Jacques and Laurent Chauvaud and Sejr, Mikael K. and Menneteau, Sylvain and Fr{\'e}d{\'e}ric Olivier} }