Data from: Shells of the bivalve Astarte moerchi give new evidence of a strong pelagic-benthic coupling shift occurring since the late 1970s in the NOW Polynya

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 'sea-ice algae-benthos' to a 'phytoplankton-zooplankton' dominance. We used mollusk shells as bioarchives and fatty acid trophic markers to estimate the effects of the reduction of sea ice cover on the exported food to the seafloor. Bathyal bivalve Astarte moerchi that lives at 600 m depth in northern Baffin Bay reveals a clear shift in growth variations and Ba/Ca ratios since the late 1970s that we relate to a change in food availability. Fatty acid compositions of tissues show that this species feeds mainly on microalgae exported from the euphotic zone to the seabed. We thus suggest that changes in pelagic-benthic coupling are likely due to either 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 change in their phenology. Both possibilities allow a more regular and increased transfer of food to the seabed.Funding provided by: ArcticNetCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100000003Award Number: Funding provided by: CHONe*Crossref Funder Registry ID: Award Number: Funding provided by: Natural Sciences and Engineering Research Council of CanadaCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100000038Award Number: Funding provided by: Canadian Healthy Oceans Network*Crossref Funder Registry ID: Award Number: Funding provided by: Québec-Océan*Crossref Funder Registry ID: Award Number: Funding provided by: Fonds de recherche du Québec – Nature et technologiesCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100003151Award Number: Funding provided by: Muséum National d'Histoire NaturelleCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100007522Award Number: Funding provided by: CHONeCrossref Funder Registry ID: Funding provided by: Canadian Healthy Oceans NetworkCrossref Funder Registry ID: Funding provided by: Québec-OcéanCrossref Funder Registry ID:see MS for all the detail