Synergistic Effects of Climate and Fishing in a Marine Ecosystem

• Published in: Ecosystems (New York) 2009-06, Vol.12 (4), p.548-561
• Main Authors: Kirby, Richard R., Beaugrand, Gregory, Lindley, John A.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Benthos; Biological and medical sciences; Biomedical and Life Sciences; Biosphere; Climate change; Climate effects; Climate models; Ecological effects; Ecology; Ecosystem studies; Ecosystems; Environmental Management; Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.); Fisheries; Fisheries management; Fishery policy; Fundamental and applied biological sciences. Psychology; General aspects; Geoecology/Natural Processes; Hydrology/Water Resources; Larvae; Larval development; Life Sciences; Marine; Marine ecology; Marine ecosystems; Overfishing; Phytoplankton; Plankton; Plant Sciences; Resource management; Sea surface temperature; Seas; Synecology; Synergistic effect; Time series; Trophic levels; Zoology
• ISSN: 1432-9840; 1435-0629
• DOI: 10.1007/s10021-009-9241-9

Current climate change and overfishing are affecting the productivity and structure of marine ecosystems. This situation is unprecedented for the marine biosphere and it is essential to understand the mechanisms and pathways by which ecosystems respond. We report that climate change and overfishing are likely to be responsible for a rapid restructuring of a highly productive marine ecosystem with effects throughout the pélagos and the benthos. In the mid-1980s, climate change, consequent modifications in the North Sea plankton, and fishing, all reduced North Sea cod recruitment. In this region, production of many benthic species respond positively and immediately to temperature. Analysis of a long-term, spatially extensive biological (plankton and cod) and physical (sea surface temperature) dataset suggests that synchronous changes in cod numbers and sea temperature have established an extensive trophic cascade favoring lower trophic level groups over economic fisheries. A proliferation of jellyfish that we detect may signal the climax of these changes. This modified North Sea ecology may provide a clear indication of the synergistic consequences of coincident climate change and overfishing. The extent of the ecosystem restructuring that has occurred in the North Sea suggests we are unlikely to reverse current climate and human-induced effects through ecosystem resource management in the short term. Rather, we should understand and adapt to new ecological regimes. This implies that fisheries management policies will have to be fully integrated with the ecological consequences of climate change to prevent a similar collapse in an exploited marine ecosystem elsewhere.