Habitat and diet preferences of the fishes Lethrinus lentjan, Siganus fuscescens and Siganus guttatus in a tropical estuary, Pujada Bay, Philippines

Abstract

The mangrove-seagrass-reef continuum is considered extremely important for many (reef) fish species providing nursery-, foraging- and hiding places. In the nursery habitat post-larvae grow out to juveniles followed by a migration from the nursery habitat to the adult habitat. These habitat migrations are set by factors related to ontogeny and could be instigated or promoted by diet shifts. Stomach-content analysis done for different size classes of fish species in different habitats may provide information on the day/night activity, habitat- and food preferences and the influence of the tidal cycle on the diet of these species. The research was performed in Pujada Bay, Philippines. Mangroves, seagrass beds and coral reefs were sampled simultaneously with bottom-set gillnets of 100 m in length. Four replicates, both for day and night catches, were performed. Stomach-content analysis was done for three species with high commercial value in the Philippines. Lethrinus lentjan is nocturnal and feeds mainly on crustaceans and polychaetes but many other prey items are present in the diet. No indication of habitat preferences could be found. Siganus fuscescens forages at night in the seagrass beds feeding mainly on different types of plant material. Many types of epifauna are present in the diet. During daytime this species hides in the mangroves. Siganus guttatus has a diurnal lifestyle and the diet consists mainly out of seagrass. No indication of habitat preferences could be found. Some of the results of the current study are inconsistent with previous research on these fish species. The inconsistency may be due to specificity of Pujada Bay, requiring further research in the Pujada Bay.