Dietary niche expansion of a kelp forest predator recovering from intense commercial exploitation

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Hamilton, S. L., Newsome, S. D., & Caselle, J. E. (2014). Dietary niche expansion of a kelp forest predator recovering from intense commercial exploitation. Ecology, 95(1), 164-172.
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TitleDietary niche expansion of a kelp forest predator recovering from intense commercial exploitation
AuthorsL. Hamilton, D. Newsome, E. Caselle
AbstractMarine ecosystems are increasingly at risk from overexploitation and fisheries collapse. As managers implement recovery plans, shifts in species interactions may occur broadly with potential consequences for ecosystem structure and function. In kelp forests off San Nicolas Island, California, USA, we describe striking changes in size structure and life history traits (e.g., size at maturation and sex change) of a heavily fished, ecologically important predator, the California sheephead (Semicossyphus pulcher). These changes occurred in two phases: (1) after intense commercial fishery exploitation in the late 1990s and (2) following recovery in the late 2000s, nearly a decade after management intervention. Using gut contents and stable-isotope values of sheephead and their prey, we found evidence for a dietary niche expansion upon recovery of population size structure to include increased consumption of sea urchins and other mobile invertebrate grazers by larger sized fish. By examining historical diet data and a time series of benthic community composition, we conclude that changes in dietary niche breadth are more likely due to the recovery of size structure from fishing than major shifts in prey availability. Size-dependent predator-prey interactions may have ecosystem consequences and management measures that preserve or restore size structure, and therefore historical trophic roles of key predators, could be vital for maintaining kelp forest ecosystem health. © 2014 by the Ecological Society of America.
JournalEcology
Date2014
Volume95
Issue1
Start page164
End page172
ISSN0012-9658
SubjectsCalifornia sheephead, Fishery, Niche breadth, Predatory-prey interactions, San Nicolas Island, Sea urchin, Semicossyphus pulcher, Stable isotopes, Trophic ecology
NoteFish and Fisheries

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