Spatio-temporal variations in abundance and assemblage patterns of fish larvae and their relationships to environmental variables in Sirindhron Reservoir of the Lower Mekong Basin, Thailand

Abstract

The spatio-temporal dynamics of fish larvae in Sirindhron Reservoir, north-east Thailand, were investigated from February 2008 to January 2009. The five most abundant species accounted for 53.6% of the total catch and comprised Clupeicthys aesarnensis, Rasbora borapetensis, Barbonymus gonionotus, Esomus metallicus and Oreochromis niloticus. Total larval abundance and species richness varied among sampling months but did not vary with zones in the reservoir. The abundance and species richness of fish larvae showed correlation with flooding, vegetation cover, water level, water temperature and turbidity. A self-organising map (SOM) was used to represent the larval fish assemblage patterns and three assemblage patterns were clearly distinguished primarily according to seasons. In conclusion, the fish larval abundance was greatest during the wet season and the most diverse assemblages were found in the zones adjacent to the connected river upstream during the wet season.