CONTRASTS IN ALGAL FOOD-PROCESSING AMONG 5 HERBIVOROUS CORAL-REEF FISHES

There were significant differences among five sympatric herbivorous re ef fish species in their ranking of seven food-processing characters. Between them Zebrasoma scopas and Stegastes nigricans had the lowest b ite rates, longest filling times, lowest defaecation activities and sl owest gut turnover. Acanthurus nigrofuscus and Scarus sordidus were si milar in having the fastest filling times, and high bite rates, gut-co ntents masses, gut turnover and defaecation activities. Ctenochaetus s triatus was intermediate between those species pairs in five out of se ven characters. Rich algal diets of S. nigricans and Z. scopas were co ntrasted with the carbonate intake of S. sordidus. The food-processing pattern of C. striatus was related to the siliceous content of a diat om diet. Food-processing characteristics of A. nigrofuscus were attrib uted to a diet which is readily absorbed and/or is of high nutritional quality. (C) 1995 The Fisheries Society of the British Isles