@article {446,
	title = {Trophic cascades in benthic marine ecosystems: lessons for fisheries and protected-area management},
	journal = {Environmental Conservation},
	volume = {27},
	year = {2000},
	abstract = {<p>An important principle of environmental science is that changes in  single components of systems are likely to have consequences elsewhere  in the same systems. In the sea, food web data are one of the few  foundations for predicting such indirect effects, whether of fishery  exploitation or following recovery in marine protected areas (MPAs). We  review the available literature on one type of indirect interaction in  benthic marine ecosystems, namely trophic cascades, which involve three  or more trophic levels connected by predation. Because many indirect  effects have been revealed through fishery exploitation, in some cases  we include humans as trophic levels. Our purpose is to establish how  widespread cascades might be, and infer how likely they are to affect  the properties of communities following the implementation of MPAs or  intensive resource exploitation. We review 39 documented cascades (eight  of which include humans as a trophic level) from 21 locations around  the world; all but two of the cascades are from shallow systems  underlain by hard substrata (kelp forests, rocky subtidal, coral reefs  and rocky intertidal). We argue that these systems are well represented  because they are accessible and also amenable to the type of work that  is necessary. Nineteen examples come from the central-eastern and  north-eastern Pacific, while no well-substantiated benthic cascades have  been reported from the NE, CE or S Atlantic, the Southern Oceans, E  Indian Ocean or NW Pacific. The absence of examples from those zones is  probably due to lack of study. Sea urchins are very prominent in the  subtidaL examples, and gastropods, especially limpets, in the intertidal  examples; we suggest that this may reflect their predation by fewer  specialist predators than is the case with fishes, but also their  conspicuousness to investigators. The variation in ecological resolution  amongst studies, and in intensity of study amongst systems and regions,  indicates that more cascades will likely be identified in due course.  Broadening the concept of cascades to include pathogenic interactions  would immediately increase the number of examples. The existing evidence  is that cascade effects are to be expected when hard-substratum systems  are subject to artisanal resource exploitation, but that the particular  problems of macroalgal overgrowth on Caribbean reefs and the expansion  of coralline barrens in the Mediterranean rocky-sublittoral will not be  readily reversed in MPAs, probably because factors other than  predation-based cascades have contributed to them in the first place.  More cascade effects are likely to be found in the soft-substratum  systems that are crucial to so many large-scale fisheries, when  opportunities such as those of MPAs and fishing gradients become  available for study of such systems, and the search is widened to less  conspicuous focal organisms such as polychaetes and crustaceans.</p>},
	keywords = {Atlantic, Carribean, ecosystem, fishery, fishery impact, food web, forest, Indian ocean, management, marine protected area, Mediterranean sea, ocean, Pacific, predation, protected area, reefs, review, rocky shore, sea urchin, trophic cascad},
	author = {J.K. Pinnegar and M. Zabala and B. Hereu and M. Harmelin-Vivien and R. Chemello and F. Badalamenti and P. Francour and N-V-C. Polunin and G. D{\textquoteright}Anna and C. Pipitone}
}
