@article {7187, title = {Shells of the bivalve Astarte moerchi give new evidence of a strong pelagic-benthic coupling shift occurring since the late 1970s in the North Water polynya}, journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences}, volume = {378}, year = {2020}, month = {Feb-10-2020}, pages = {20190353}, abstract = {Climate changes in the Arctic may weaken the currently tight pelagic-benthic coupling. In response to decreasing sea ice cover, arctic marine systems are expected to shift from a {\textquoteleft}sea-ice algae{\textendash}benthos{\textquoteright} to a {\textquoteleft}phytoplankton-zooplankton{\textquoteright} dominance. We used mollusc shells as bioarchives and fatty acid trophic markers to estimate the effects of the reduction of sea ice cover on the food exported to the seafloor. Bathyal bivalve\ Astarte moerchi\ living at 600 m depth in northern Baffin Bay reveals a clear shift in growth variations and Ba/Ca ratios since the late 1970s, which we relate to a change in food availability. Tissue fatty acid compositions show that this species feeds mainly on microalgae exported from the euphotic zone to the seabed. We, therefore, suggest that changes in pelagic-benthic coupling are likely due either to local changes in sea ice dynamics, mediated through bottom-up regulation exerted by sea ice on phytoplankton production, or to a mismatch between phytoplankton bloom and zooplankton grazing due to phenological change. Both possibilities allow a more regular and increased transfer of food to the seabed.

This article is part of the theme issue {\textquoteleft}The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning{\textquoteright}.}, issn = {1364-503X}, doi = {10.1098/rsta.2019.0353}, url = {https://royalsocietypublishing.org/doi/10.1098/rsta.2019.0353}, author = {Fr{\'e}d{\'e}ric Olivier and Gaillard, Blandine and Thebault, Julien and Tarik Meziane and Tremblay, Rejean and Dumont, Dany and B{\'e}langer, Simon and Gosselin, Michel and Jolivet, Aur{\'e}lie and Chauvaud, Laurent and Martel, Andr{\'e} L. and Rysgaard, S{\o}ren and Olivier, Anne-H{\'e}l{\`e}ne and Pettr{\'e}, Julien and Mars, J{\'e}r{\^o}me and Gerber, Silvain and Archambault, Philippe} } @article {3488, title = {Veliger Size at Metamorphosis and Temporal Variability in Prodissoconch II Morphometry in the Blue Mussel (Mytilus edulis): Potential Impact on Recruitment}, journal = {Journal of Shellfish Research}, volume = {33}, year = {2014}, month = {08/2014}, pages = {443-455}, abstract = {

Examination of the larval shell (prodissoconch) of molluscs with planktotrophic development can provide valuable information on their planktonic and early benthic life. We examined temporal variability of abundance and size among 11,994 veligers of the blue mussel (Mytilus edulis) in a coastal lagoon during settling periods between 1995 and 2009. Size and date at metamorphosis during the recruitment season were determined for 1,925 postlarvae (shell length, 255{\textendash}900 {\textmu}m) with prodissoconch II (PII) measurements. Emphasizing the recurrence of metamorphosis delay in the field, our study reveals a net increase in mean size at metamorphosis through time, with means for PII size ranging from 255{\textendash}288 {\textmu}m early in summer (after peak spawning events) to 400{\textendash}422 {\textmu}m (PII) during late July to early September. By estimating the {\textquotedblleft}true{\textquotedblright} settlement date using the amount of dissoconch secreted after metamorphosis, such time-series analyses appropriately recapitulated the temporal pattern of mean pediveliger (competent larvae) size in the plankton. Our results demonstrate that greater settlement success rates were related to small size at metamorphosis{\textemdash}in particular, less than 320 {\textmu}m. Seasonal increase in mean PII size occurring during the latter part of the settling period may be explained by competent veligers remaining adrift and delayed metamorphosis as a result of the lack of favorable encounters with a suitable substrate or the absence of specific trophic signals, or cues, required for stimulating settlement, thus forcing larvae to continue planktonic growth. The difference between the smallest and largest means for PII size corresponds to 122 {\textmu}m of larval shell growth, or 47.8\%, potentially representing a 322\% difference in larval body mass at settlement.

}, keywords = {blue mussel, delayed metamorphosis, larval settlement, Mytilus edulis, prodissoconch II, recruitment, veligers}, doi = {http://dx.doi.org/10.2983/035.033.0213}, url = {http://www.bioone.org/doi/full/10.2983/035.033.0213}, author = {Martel, Andr{\'e} L. and R{\'e}jean Tremblay and Nicolas Toupoint and Fr{\'e}d{\'e}ric Olivier and Myrand, B} }