Publication Abstract

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

G.M. Daskalov, A.N. Grishin, S. Rodionov and V. Mihneva

Large-scale transitions between alternative states in ecosystems are known as regime shifts. The Black Sea ecosystem has experienced large-scale disturbances such as fish stock collapse, eutrophication, and alien introduction. We studied changes related to these “natural experiments” in order 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 a challenge to the existing paradigms and to deliver explanatory models that can better reconcile conservation and ecosystem management ideals.

Reference

G.M. Daskalov, A.N. Grishin, S. Rodionov and V. Mihneva (2007) Trophic cascades triggered by overfishing reveal possible mechanisms of ecosystem regime shifts. America, 104(25): 10518-10523