SMALL-SCALE RECRUITMENT VARIATION IN A TEMPERATE FISH - THE ROLES OF MACROPHYTES AND FOOD-SUPPLY

The availability of reef-related resources, particularly food and shel ter can play a significant role in determining the distribution and ab undance of reef fishes. Much of the structure on temperate reefs is pr ovided by macroalgae, and variability in the density of temperate reef fishes at large spatial scales (100's of meters) can often be explain ed by variation in macroalgal cover or density. In this study I invest igated the role of macrophytes and associated food resources on the re cruitment of a temperate fish, Tautogolabrus adspersus, at a small spa tial scale (0.25 m(2)). No relationship between the density of new rec ruits and the percent cover of kelp, foliose or filamentous algae was observed. Multiple regressions revealed that less than 8% of variabili ty in recruitment could be explained by variability in macroalgal cove r. However, recruits were found in higher abundance in patches contain ing many functional forms of seaweeds than in patches dominated by a s ingle form. A wide variety of prey were available for use by cunner re cruits; however, crustaceans and mussels were the only common componen ts of their diet, and crustaceans were clearly the most preferred prey . The prey composition in patches where fish were present was compared to randomly selected patches. Significantly greater numbers of isopod s, amphipods and newly settled mussels were present in patches where f ish were present than in randomly selected patches. The data presented in this study contradict previous work that has shown algal structure to be important in determining patterns of abundance and food supply to be of little significance. A conceptual model is proposed suggestin g that settling fish select habitats in a hierarchical manner largely based on their dispersal tendencies. Hierarchical selection of habitat s results in different attributes of the habitat being selected during different life-history intervals.