Abstract

Climate change, eutrophication, and fishing are main pressures associated with changes in the abiotic and biotic environment in several sub-basins of the Baltic Sea. Identifying the nature of such changes is of relative importance for fisheries and environmental management. The Bothnian Bay is the northernmost sub-basin in the Baltic Sea and the responses of the foodweb to long-term changes in combined pressures have not been investigated. In this study, we explore long-term changes in the Bothnian Bay foodweb, represented by key species across all trophic levels over the past 34 years, and identify potential environmental and anthropogenic drivers. The results indicate that salinity is the most important driver to explain changes in the composition of the offshore biota in the Bothnian Bay. These changes are probably driven by indirect effects of salinity rather than bottom-up effects. A decline in the herring spawning-stock biomass was most plausibly attributed to an increased competition for food due to a parallel increase in vendace, which uses the same food resources (zooplankton and zoobenthos) and may benefit from declining salinity due to its limnic origin. A strong increase in the abundance of grey seal and ringed seal populations was seen in the late 2000s but was not related to any of the pressure variables analysed. Temperature and nutrients were not identified as important drivers of changes in the overall biota. Our study explores correlative relationships between variables and identifies potential interactions in the foodweb to generate hypotheses for further studies.

Keywords

climate; fisheries; grey seal; herring spawning-stock biomass; ringed seal; salinity

Published in

ICES Journal of Marine Science
2016, Volume: 73, number: 7, pages: 1739-1749
Publisher: OXFORD UNIV PRESS

SLU Authors

• Hekim, Zeynep

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

• Gårdmark, Anna

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

• Karlsson, Agnes

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

• Bergenius Nord, Mikaela

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

• Bergström, Lena

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

Sustainable Development Goals

Conserve and sustainably use the oceans, seas and marine resources for sustainable development


UKÄ Subject classification

Fish and Aquacultural Science
Ecology


Publication identifier

DOI: https://doi.org/10.1093/icesjms/fsw032

Permanent link to this page (URI)

https://res.slu.se/id/publ/79888