Biology of the Black-stripe minnow Galaxiella nigrostriata, (Galaxiidae) in an acidic, black-water lake in Melaleuca Park near Perth, Western Australia

WA Museum Records and Supplements | Updated 6 years ago

ABSTRACT – Individuals of GalaxieIla nigrostriata (Shipway) from acidic, temporary, black-water wetland designated EPP 173 at Melaleuca Park, Ellen Brook, Western Australia, are compared with members from the main area of distribution of the species some 350+ km further south in Western Australia. They were found to be similar to the southern populations in size frequency distribution and habitat. Adult fish from EPP 173 were first sampled, and breed, one month later than those from southern sites. Diets of all populations were similar, comprising predominantly microcrustaceans, dipterans and rotifers; however, prey items at the water surface were consumed less commonly by the northern specimens. G. nigrostriata was found to be sensitive to high water temperatures. Laboratory trials showed that the fish cannot tolerate, for more than a few seconds, temperatures >26°C but preferred a temperature of 14.5°C. The survival of the G. nigrostriata population in EPP 173 is related to the strong thermal stratification which develops on hot days, with the surface water temperature typically reaching values >26°C but overlying cooler bottom water around 15°C which provides a cool water refuge for the resident fish population. The northern outlier population in EPP 173 occurs in the path of the urban expansion of Perth and, since it has high intrinsic conservation value, its management for conservation is paramount.