RESPONSE OF LARVAL FISH ASSEMBLAGES TO A RIVERINE PLUME IN COASTAL WATERS OF THE CENTRAL GREAT-BARRIER-REEF LAGOON

Ichthyoplankton assemblages were compared among stations in the vicini ty of a riverine plume in coastal wafers of the central Great Barrier Reef lagoon, Australia, during January 1991. Although the plume dramat ically influenced both community structure and abundance of larval fis h, effects were temporally dynamic and taxon-specific. Mullids were th e only family to show significantly higher densities at the plume fron t than either inside or outside the plume. Samples from the plume fron t and coastal waters outside the plume showed similar taxonomic affini ties. These affinities appeared to be driven by the offshore movement of the plume translocating coastal larvae offshore, which also led to accumulation of these larvae at the plume front. Given the large area that the plume covered and the high zooplankton biomass and secondary production in these waters, we suggest that the plume may have affecte d larval fish survival and recruitment more than the associated plume front.