Habitat-specific distributions of some fishes in a tropical estuary

Abstract

The species richness of fishes and the distributions of six fish species were compared among four habitat types, snaggy banks, clear banks, mud banks and mid channels, in an estuary in tropical Australia. Both day and night samples were collected in fish traps, on four occasions, three months apart. On each sampling trip the highest number of species was trapped from snaggy habitats, intermediate numbers from clear banks or mud banks, and the fewest species from mid channels. Although more species occurred in night than in day samples, the pattern of difference among habitats was consistent. The probability of capture of the six most abundant species, Acanthopagrus australis, Acanthopagrus berda, Arothron manilensis, Arius argyropleuron, Epinephelus coioides and Lutjanus russelli, was compared among habitat types and between day and night samples. Overall, snag habitats tended to be associated with high probabilities of capture of a number of species, particularly A. berda and L. russelli. At night, mid channels were characterized by high numbers of A. argyropleuron. Clear and mud banks, and day samples from mid channels were associated with low numbers of most species.