Hydrology and fish diversity of a North Queensland tropical stream

Abstract The diversity and distribution of fish and the hydrology of the Black-Alice River System, North Queensland, are described from a 2-year study (September 1972 to August 1974). Most physico-chemical parameters measured exhibited seasonal patterns which are influenced by rainfall and discharge. A total of forty-one species of fishes belonging to four groups: freshwater tolerant, saltwater tolerant, diadromous and sporadic, were recorded during the study. The diversity of fish species decreased with increasing distance from the mouth of the system. Fluctuations in total diversity (H') were due to variations in ‘species richness’ (D) rather than to equitability (E). The ability of the fish community to ‘recover’ its diversity and longitudinal distribution after a flood of above-average magnitude is demonstrated.