Damselfish as Keystone Species in Reverse: Intermediate Disturbance and Diversity of Reef Algae

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Science  29 Apr 1983:
Vol. 220, Issue 4596, pp. 511-513
DOI: 10.1126/science.220.4596.511


Substrates located within the defended territories of Hawaiian damselfish for 1 year were subjected to intermediate grazing intensity and, as a result, showed greater diversity of algae than substrates either protected within fish-exclusion cages or exposed to intense fish grazing outside territories. Thus, this damselfish enhances local diversity on reefs through "intermediate-disturbance" effects, and is a keystone species that decreases rather than increases overall predation intensity relative to areas where it is absent.