Abundance and distribution of Stolephorus baganensis Hardenberg 1933 and Thryssa kammalensis (Bleeker 1849) larvae in relation to ontogeny and environmental factors in a Malaysian estuary

Abstract

Larval abundance and distribution of Stolephorus baganensis Hardenberg 1933 and Thryssa kammalensis (Bleeker 1849), two species of anchovies in the Selangor River estuary, were related to water parameters, planktonic biomass and individual developmental stages. Ontogenetic shifts in these relationships were observed for both species, suggesting that larval adaptiveness is crucial to the estuary’s use as a nursery area. Both species are multiple spawners, spawning all year round but with peaks of intensity. In the case of S. baganensis, mass spawning occurred from April to July in clear and relatively deep coastal waters and was associated with an increase in dissolved oxygen and food availability. At approximately 10.0 mm SL, larvae moved towards shallower and more turbid waters where they remained until the juvenile stage. T. kammalensis spawning peaks were observed at approximately 3-month intervals without any strong association with the abiotic parameters considered. Their spawning ground was located in the shallow waters of the estuary. At approximately 10.0 mm SL, larvae moved upstream where they remained until the juvenile stage. This study does not fully support the match-mismatch hypothesis for tropical waters.