A single measure of salinity: Is this representative of a river's past salinity?

Ecological surveys of streams frequently relate aquatic biota to a single instantaneous measurement of water quality and assume that this measurement reflects past water quality. How well a single instantaneous measurement of electrical conductivity (EC), μS cm−1, represented EC over the past 28 days was assessed in three rivers in southwest Victoria, Australia. Results showed that an instantaneous measurement of EC did represent both spatial and temporal variations at a site over the past 28 days, suggesting that it is appropriate to relate biota at a site to concurrent single instantaneous measurements of salinity.