High and often variable salinity is an obvious feature of salt lakes. Correspondingly, salinity is usually assumed to be an important ecological determinant in such lakes. An investigation of the macroinvertebrate fauna of 79 lakes (salinities from 0.3 to 343 g 1-') in the Western District of Victoria, Australia, examined this assumption. Over the total range of salinity, species richness and composition are highly correlated with salinity. However, these relationships become nonsignificant over intermediate ranges of salinity. Furthermore, many taxa have very broad tolerances to salinity at these intermediate ranges, implying that factors other than salinity may determine their distribution. An appreciation of scale (that is, the range of salinity over which observations are considered) resolves the paradox that, despite these broad tolerances by most taxa, species richness and composition strongly reflect salinity over the entire salinity range. 16.5, 20.0 2

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Surveys were made of the macroinvertebrates at several locations on the Blackwood River, Western Australia, and the Glenelg River,Victoria. Both rivers have drainage basins subject to salinization from agricultural practices. The Blackwood River has a clear longitudinal salinity profile in which the upper reaches are more saline than lower ones. Multivariate analysis using DECORANA and TWINSPAN did not reveal relationships between macroinvertebrate community composition and salinity. It is suggested that either the present macroinvertebrate fauna of Australian rivers is more tolerant to salinity than has been assumed, or now represents only halotolerant forms of a once more diverse fauna.