Year of Publication
2020

Journal

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Volume
378
Issue
2181
Date Published
Feb-10-2020
Number of Pages
20190353
DOI
10.1098/rsta.2019.0353
URL
https://royalsocietypublishing.org/doi/10.1098/rsta.2019.0353
ISSN Number
1364-503X
HCERES category
ACL - Articles in international or national peer-reviewed journals indexed by HCERES or in international databases
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 ‘sea-ice algae–benthos' to a ‘phytoplankton-zooplankton’ 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&nbsp;Astarte moerchi&nbsp;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.<br>
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This article is part of the theme issue ‘The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.