POSTSETTLEMENT GROWTH AND BODY-COMPOSITION IN RELATION TO FOOD AVAILABILITY IN A JUVENILE TROPICAL REEF FISH

Pomacentrus amboinensis is an abundant, predominantly planktivorous reef fish which settles into a range of habitats from sheltered lagoons to exposed windward reefs. Recruits are exposed to differences in food availability as a function of the physical dynamics of the habitat. This study examines the effects of a variable food supply on somatic development and the deposition of energy reserves in recently settled fish. Food availability had a complex and significant effect on levels of energy reserves. Trends in lipid content between treatments were similar to those for somatic growth. A 3.5-fold difference in total lipid existed between fully fed and field fish. The lipid content of field fish was similar to starved fish. Trends in the water content of tissues were the inverse of those of total lipid; fish in 'poor' condition and with a slower growth rate had a relatively higher water content. Food availability had no effect on the levels of protein, but elevated levels of protein were detected in field fish compared to all experimental fish. There was a close relationship between feeding history, somatic growth, and levels of energy reserves, principally total lipid concentration.