Spatial and seasonal patterns of habitat partitioning in a guild of southern California tidepool fishes

Five species of fish, Clinocottus analis, Girella nigricans, Hypsoblennius gilberti, Gobiesox rhessodon, and Gibbonsia elegans, commonly occur in sout hern California's rocky intertidal zone. To examine the extent to which tid epool 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 pertai ning to the segregation of habitat among different species and different si ze classes within species relative to the tidepool characteristics of inter tidal height, surface area, depth, rugosity, and percent algal cover. A man ipulative field experiment was conducted to further investigate these resul ts. Tidepools were partitioned among and within fish species. Tidepool char acteristics most important in partitioning were intertidal height, depth, a nd rugosity, with the order of importance of these characteristics differen t for each species. Habitat partitioning between size classes within specie s, although not as great as partitioning among species, was also based larg ely on tidepool intertidal height and rugosity. Although fish abundance cha nged seasonally, species' distribution patterns, with the exception of C. a nalis, were seasonally stable. The seasonal change in C. analis distributio n was due to the arrival of new recruits rather than a seasonal change in a dult 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 lo w tide.