Larval fish assemblages in south-east Australian coastal waters: Seasonal and spatial structure

Seasonal, vertical and horizontal differences in the larval fish assemblage s occurring in temperate inner continental shelf waters off Sydney, south-e astern Australia, between December 1989 and February 1993 are assessed and related to the regional oceanography. Carangids, clupeids and bothids numer ically dominated the diverse larval fish fauna, which comprised 173 identif iable taxa from 119 families. Assemblages were depth stratified between the surface and mid-water depths of 20-30 m during the day in all seasons, wit h greater numbers of taxa and individuals generally occurring in the mid-wa ter strata. Multivariate analyses showed that there were differences in ass emblages sampled at sites 0.5-5 km from shore, but there were no consistent cross-shelf (<5 km) differences in abundances of larvae, probably because of the dynamic nature of currents in the study region. Recurrent and distin ct autumn (April-June), winter (July-August) and spring/summer (September-M arch) larval fish groups were evident in surface and mid-waters, but these groups were not restricted to any particular oceanographic condition. Membe rship of the seasonal groups was dynamic as many taxa occurred across more than one season, and some year round. The recurrent nature of the larval gr oups most likely reflected the temporal coherence of spawning of adults, la rval behaviour and interactions with dominant currents. (C) 2000 Academic P ress.