ABSTRACT: Five species of fish, Clinocottus analis, Girella nigricans, Hypsoblennius gilberti, Gobiesox rhessodon, and Gibbonsia elegans, commonly occur in southern California's rocky intertidal zone. To examine the extent to which tidepool habitat is segregated by the 5 fishes, habitat partitioning patterns among and within the species were determined at 2 sites in San Diego. Fish density, species composition, and fish size were measured in 105 tidepools every 3 mo from November 1996 to August 1997. Hypotheses were tested pertaining to the segregation of habitat among different species and different size classes within species relative to the tidepool characteristics of intertidal height, surface area, depth, rugosity, and percent algal cover. A manipulative field experiment was conducted to further investigate these results. Tidepools were partitioned among and within fish species. Tidepool characteristics most important in partitioning were intertidal height, depth, and rugosity, with the order of importance of these characteristics different for each species. Habitat partitioning between size classes within species, although not as great as partitioning among species, was also based largely on tidepool intertidal height and rugosity. Although fish abundance changed seasonally, species' distribution patterns, with the exception of C. analis, were seasonally stable. The seasonal change in C. analis distribution was due to the arrival of new recruits rather than a seasonal change in adult habitat. The use of different types of tidepools by different species and by different size classes within species serves to limit contact among these groups, and therefore both direct and indirect competition, during low tide.

KEY WORDS: Fish · Rocky intertidal zone · Clinocottus analis · Girella nigricans · Hypsoblennius gilberti · Gobiesox rhessodon · Gibbonsia elegans

Published in MEPS Vol. 196 (2000) on April 18
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 2000