Trophic cascades promote threshold-like shifts in pelagic marine ecosystems.

Casini, M., Hjelm, J., Molinero, Juan Carlos, Lövgren, J., Cardinale, M., Bartolino, V., Belgrano, A. and Kornilovs, G. (2009) Trophic cascades promote threshold-like shifts in pelagic marine ecosystems. PNAS Proceedings of the National Academy of Sciences of the United States of America, 106 . pp. 197-202. DOI 10.1073/pnas.0806649105.

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Fisheries can have a large impact on marine ecosystems, because the effects of removing large predatory fish may cascade down the food web. The implications of these cascading processes on system functioning and resilience remain a source of intense scientific debate. By using field data covering a 30-year period, we show for the Baltic Sea that the underlying mechanisms of trophic cascades produced a shift in ecosystem functioning after the collapse of the top predator cod. We identified an ecological threshold, corresponding to a planktivore abundance of ≈17 × 1010 individuals, that separates 2 ecosystem configurations in which zooplankton dynamics are driven by either hydroclimatic forces or predation pressure. Abundances of the planktivore sprat above the threshold decouple zooplankton dynamics from hydrological circumstances. The current strong regulation by sprat of the feeding resources for larval cod may hinder cod recovery and the return of the ecosystem to a prior state. This calls for the inclusion of a food web perspective in management decisions.

Document Type: Article
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EOE-N Experimental Ecology - Food Webs
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1073/pnas.0806649105
ISSN: 0027-8424
Projects: Future Ocean
Date Deposited: 28 Jan 2009 15:45
Last Modified: 14 Nov 2016 12:18

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