MEPS 138:83-92 (1996)  -  doi:10.3354/meps138083

Consumer mobility and the relative importance of consumption and competition following physical disturbance

Breitburg DL

Simple models and an example from the published literature suggest how consumer mobility can alter the relative importance to producers of consumption (predation and herbivory) and competition following a disturbance that opens habitat for colonization. Highly mobile consumer species often can colonize disturbed habitat at juvenile and adult life stages with high per capita consumption rates. In contrast, consumers with limited mobility, as well as sessile or sedentary prey, can be restricted to colonization of disturbed habitat by reproductive propagules, and initially have low per capita consumption, and low biomass and per capita production, respectively. Following a disturbance, the relationship between potential consumption and production can differ in important ways from that prior to the disturbance if consumer and prey species differ markedly in mobility, but may be similar to that prior to the disturbance if consumers and prey are both limited to colonization by reproductive propagules. Functional responses of consumers, and growth rates of consumers relative to producers, can determine how strongly consumer mobility will influence post-disturbance interactions. In California (USA) kelp forests, sea urchins may be able to colonize disturbed patches as adults or can be restricted to colonization by larval settlement depending on habitat characteristics and how their foraging behavior affects sea urchin susceptibility to winter storms. On Naples Reef, near Santa Barbara, California, recovery of macroalgae including giant kelp was inhibited under grazing by adult urchins but was rapid when sea urchins colonized through larval settlement.

Competition . Consumers . Kelp bed . Mobility . Model . Physical disturbance . Predation . Sea urchin

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