Multi-decadal trends in biomarkers in harp seal teeth from the North Atlantic reveal the influence of prey availability on seal trophic position

• Published in: Global Change Biology
• Main Authors: de la Vega, Camille, Kershaw, Joanna, Stenson, Garry B, Frie, Anne Kirstine, Biuw, Martin, Haug, Tore, Norman, Louisa, Mahaffey, Claire, Smout, Sophie, Jeffreys, Rachel M
• Other Authors: NERC, University of St Andrews. School of Biology, University of St Andrews. Sea Mammal Research Unit, University of St Andrews. Scottish Oceans Institute, University of St Andrews. Centre for Research into Ecological & Environmental Modelling, University of St Andrews. Coastal Resources Management Group
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: DAS; MCP; Arctic; Arctic Ocean; Barents Sea; Greenland; Greenland Sea; Harp Seal; North Atlantic; Northwest Atlantic
• Online Access: http://hdl.handle.net/10023/28024; https://doi.org/10.1111/gcb.16889

This work resulted from the ARISE project (NE/P006035 awarded to RJ and CM at Liverpool University, NE/P00623X awarded to SS at St. Andrews), part of the Changing Arctic Ocean programme, funded by the UKRI Natural Environment Research Council (NERC). Arctic food webs are being impacted by borealisation and environmental change. To quantify the impact of these multiple forcings, it is crucial to accurately determine the temporal change in key ecosystem metrics, such as trophic position of top predators. Here, we measured stable nitrogen isotopes (δ15 N) in amino acids in harp seal teeth from across the North Atlantic spanning a period of 60 years to robustly assess multi-decadal trends in harp seal trophic position, accounting for changes in δ15 N at the base of the food web. We reveal long-term variations in trophic position of harp seals which are likely to reflect fluctuations in prey availability, specifically fish- or invertebrate-dominated diets. We show that the temporal trends in harp seal trophic position differ between the Northwest Atlantic, Greenland Sea and Barents Sea, suggesting divergent changes in each local ecosystem. Our results provide invaluable data for population dynamic and ecotoxicology studies. Publisher PDF Peer reviewed