BENTHIC MACROINVERTEBRATE COMMUNITY STRUCTURE IN STREAMS OF DIFFERENTSALINITIES

The likely effect of salinization on stream invertebrates was studied by comparing macroinvertebrate community structure at nine sites in si x lowland, perennially flowing streams. The salinity of these streams ranged from 51 to 1100 mg L-1 total dissolved solids (TDS) (and were h istorically higher, up to about 2000 mg L-1 TDS). There was no correla tion between either number of taxa or faunal abundance with salinity. However, multivariate analyses showed distinct invertebrate communitie s associated with different salinities. Fidelity analysis identified g roups of taxa associated with either low or high salinity. Existing in formation on the distribution of the common taxa within these groups i ndicated that they were tolerant of wider ranges in salinity than thos e found in this study. The rare taxa most clearly distinguished betwee n sites of different salinities and are possibly more sensitive to cha nges in salinity.