Abstract: Local species richness and evenness of a prey assemblage can change in a variety of patterns as the intensity of predation by fishes increases. Documenting this pattern requires measurements of prey diversity at a minimum of three widely spaced predation intensities. The particular pattern that occurs depends largely upon: (1) the processes structuring the prey assemblage in the absence of fish predation (recruitment limitation, physical disturbances, non-fish predators, mutualisms, competitive networks, or competitive hierarchies); (2) the pattern of prey population reduction by fish predation (equivalent, disproportionate on competitive dominants, or disproportionate on competitive subordinates); and (3) the processes governing local extinctions and immigrations in the prey assemblage (prey refuges, recruitment patterns, and local versus global species richness). A literature review of the impact of fish predation on other fishes, plankton, and benthos in a variety of freshwater and marine systems indicated that local effects on prey diversity are seldom documented adequately. Only seven experiments documented both prey diversity as a function of at least three predation intensities, as well as the probable mechanisms underlying the prey diversity response. Of these, two studies of freshwater benthos detected virtually no effects on prey diversity, apparently due to rapid prey recolonization or predator inefficiency. Two studies of freshwater zooplankton and three studies of coral-reef algae detected keystone-predator induced hump-shaped patterns characteristic of the intermediate-disturbance hypothesis. Two additional studies of coral-reef benthos detected negative effects on prey diversity over a range of at least three predation intensities, but the underlying mechanisms were unclear. Spatial prey refuges, particularly those provided by aquatic plants on soft bottoms and crevices on hard bottoms, have been shown to minimize the effects of fish predation on the diversity of benthic assemblages in both freshwater and marine systems. The concepts summarized in this paper suggest improvements for future studies of the impact of fishes on prey community structure.
Publication Year: 1986
Publication Date: 1986-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
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Cited By Count: 49
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