Diet and feeding strategy of the common silver-biddy, Gerres oyena (Forsskål 1775) in the seagrass beds of Karang Congkak Island, Kepulauan Seribu National Park

Abstract

Abstract Diet and feeding ecology studies are a principal tool to understand the functional role of fish within their habitat. Like most coastal habitats, seagrass meadow provides food and refuge for many biotas. Karang Congkak Island is a small uninhabited island situated in the northern part of the Kepulauan Seribu National Park and surrounded by a seagrass ecosystem. The current study aims to analyze diet composition changes and trophic attributes of the common silver-biddy, Gerres oyena, in the seagrass ecosystem of the Karang Congkak Island. The research was carried out monthly from March to September 2018 by towing the beach seine net. Data analysis includes diet composition, niche breadth, and feeding strategy. During the study period, 1,196 individuals of G. oyena were captured, and most of them were juveniles. Fifty-nine types of prey were documented and arranged into six groups, namely phytoplankton, algae, zooplankton, zoobenthos, crustaceans, and unidentified material. G. oyena shows an ontogenetic change, from zooplanktivore to crustacivore and zoobenthivore. Moreover, this species has a TROPH value ranging from 3.00-3.31 and is categorized as omnivorous that tend to feed on animals. The interpretation of prey-specific abundance and niche breadth confirms that this species developed specialized and generalized feeding strategies.