Fish of Trinity Inlet system of north Queensland with notes on the ecology of fish faunas of tropical Indo-Pacific estuaries

Abstract

The fish faunas of tropical Trinity estuary and adjacent Trinity Bay are described. The fauna of the estuary is compared with that of other tropical Indo-Pacific estuaries and is found to be similar: all are dominated by juvenile marine fish. Numbers of planktivores are high and swimming prawns are an important food for many species. Absence of extensive shallow areas and a low biomass of benthic animals in Trinity estuary apparently limits the numbers of benthic feeding fish. Piscivores are few in the estuary and mainly represented by juveniles. Trinity Bay has fewer species represented by juveniles than the estuaries. higher numbers of piscivores, mainly adults, and fewer planktivores. The species diversity of Mugilidae in all areas is probably influenced by substrate diversity. Physical data indicate that substrate, turbidity and depth, together with relatively calm water in estuaries, affect the distribution ofjuvenile marine fish. If Trinity Bay is representative of areas of open water adjacent to tropical estuaries, the significantly lower numbers of piscivores in the estuaries may increase their advantage as sanctuaries for juvenile fish.