EFFECTS OF SALINITY ON THE DISTRIBUTION OF CALOGLOSSA LEPRIEURII (RHODOPHYTA) IN THE BRISBANE RIVER,AUSTRALIA1

The role of salinity as a factor determining the distribution of two red algal taxa, Caloglossa leprieurii (Mont.) J. Ag. var. leprieurii and Caloglossa leprieurii var. angusta Jao, along the course of the Brisbane River, Queensland, Australia, was investigated. In the field, C. leprieurii var. angusta tolerated a narrower salinity range (mean salinity = 0.0–18.9) than C. leprieurii var. leprieurii (mean salinity = 2.0–33.8) and occupied areas of lower salinity (salinity expressed according to the Practical Salinity Scale of 1978). Both taxa coexisted for a distance of 23 km along the middle reaches of the river. Cell measurements of specimens of both taxa collected along the river showed an increase in cell sizes upstream from the mouth. Results of a reciprocal transplant experiment and growth responses in a series of laboratory culture studies of the two taxa in a range of salinities are presented. These could be correlated with the field distribution of the algae, demonstrating their euryhalinity and the presence of distinct salinity ecotypes.