Publication Date

Summer 2011

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Moss Landing Marine Laboratories

Advisor

Gregor M. Cailliet

Keywords

benthic invertebrates, diet, feeding ecology, Goper Rockfish, marine protected areas

Subject Areas

Ecology; Conservation biology

Abstract

Marine protected areas (MPAs) can potentially impact food web dynamics by increasing the density of predatory fishes within their borders. Such increases in density can cause shifts in the prey use of generalist predators. This study investigated the effects of increased conspecific density on the diet of Gopher Rockfish (Sebastes carnatus) at a 35-year-old MPA at Point Lobos and four newly established central California MPAs at Año Nuevo, Point Lobos, Piedras Blancas, and Point Buchon. Analysis of 710 stomachs collected in 2007-2009 indicated the most important overall prey were crabs, especially of the family Pisidae and the genus Cancer, as well as brittle stars and mysids. Diets did not differ inside versus outside the old Point Lobos MPA in terms of prey richness, evenness, and composition. Trophic level and individual specialization also did not differ. No consistent differences in these metrics were observed inside versus outside the four new MPAs, although prey evenness and composition did differ significantly among geographic locations. Diets at Año Nuevo, the most northern and shallow collection location, were dominated by Cancer crabs and porcelain crabs, while diets from southern, deeper locations were dominated by brittle stars. The case study of the old Point Lobos MPA indicates that changes in fish feeding ecology in MPAs may take decades to occur, if at all. Differences in prey observed among geographic locations suggest variation in the community composition among central California's new MPAs, which may influence the effect of each MPA on food web dynamics over time.

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