Trophic cascades triggered by overfishing reveal possible mechanisms of ecosystem regime shifts

Large-scale transitions between alternative states in ecosystems are known as regime shifts. Once described as healthy and dominated by various marine predators, the Black Sea ecosystem by the late 20th century had experienced anthropogenic impacts such as heavy fishing, cultural eutrophication, and...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2007-06, Vol.104 (25), p.10518-10523
Main Authors: Daskalov, Georgi M, Grishin, Alexander N, Rodionov, Sergei, Mihneva, Vesselina
Format: Article
Language:English
Subjects:
Animals
Aquatic ecosystems
Biological Sciences
Biomass
Brackish
Coastal zone management
Ctenophora - physiology
Ecosystem
Ecosystems
Eutrophication
Fish
Fisheries - methods
Fishes - physiology
Fishing
Food Chain
Marine Biology
Marine conservation
Marine ecosystems
Mnemiopsis leidyi
Models, Theoretical
Oceans and Seas
Phytoplankton
Plankton
Population Density
Predation
Predators
Trophic cascades
Trophic levels
Zooplankton
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Summary:Large-scale transitions between alternative states in ecosystems are known as regime shifts. Once described as healthy and dominated by various marine predators, the Black Sea ecosystem by the late 20th century had experienced anthropogenic impacts such as heavy fishing, cultural eutrophication, and invasions by alien species. We studied changes related to these "natural experiments" to reveal the mechanisms of regime shifts. Two major shifts were detected, the first related to a depletion of marine predators and the second to an outburst of the alien comb jelly Mnemiopsis leidyi; both shifts were triggered by intense fishing resulting in system-wide trophic cascades. The complex nature of ecosystem responses to human activities calls for more elaborate approaches than currently provided by traditional environmental and fisheries management. This implies challenging existing practices and implementing explanatory models of ecosystem interactions that can better reconcile conservation and ecosystem management ideals.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0701100104