Species composition and food preference of fishes in two seagrass beds in Taklong Island, Guimaras

Abstract

Seagrass bed is known as one of the most important biological system that serves as nursery areas, resting and hiding place of small organisms and feeding ground for fishes. Investigations on population structure and composition of fishes have been done to monitor species diversity, abundance, and distribution in seagrass ecosystem. However, few studies have related food preference to community structure. This study aims to determine the species composition and food preference of fishes in Bagatnan and Kalirohan seagrass beds in Taklong Island, Guimaras. Once-a-month sampling in Taklong Island was conducted during the months of October, November, and December 1996. The collection of fishes was done using gill net. It was casted —50 meters from the shore and parallel to the shore during high tide and hauled during the next low tide. All gathered fishes were measured and preserved in 10% formalin. For stomach content analysis, stomachs of fishes were excised, preserved and brought to the laboratory for analysis. Contents were flushed out from the stomach, sorted and identified to major groups (as food items). Based on the results of the study,Siganus fuscecens, Scarus psittacus, and Dichistodus chrysopoecilus were the most abundant species of fish collected in Bagatnan and Kalirohan seagrass beds Kalirohan had a slightly higher species diversity and species richness value than Bagatnan. Most of the fishes caught were omnivores and this feeding mode was clearly reflected in the results of the stomach content analyses Also, the most abundant and common species (e.g. S. fuscecens & Dischistodus spp) had various food items on their stomach. Seagrass blades, algae, foraminiferans and other seagrass-associated organisms (e g. fishes, sipunculids, crustaceans and molluscs) were present in the stomach of many species. Of these, foraminiferans are the most frequently encountered among the food items. A few species fed on single item such as Synodus variegatus, Atherioromorus sp. and Amanses scopes which were found to feed exclusively on fish, algae and seagrass respectively. Although factors like type of fishing gear used and its mesh size and the time of sampling may have biased the kind and size of fish collected, it was clear that the extent of seagrass cover and availability of other food sources (algae and meio- & macrofauna) have influenced the abundance, species diversity & richness and the food consumed (and perhaps, also preferred) by the fish fauna.