Floodplain biodiversity: why are there so many species?

Spring surveys of 112 temporary floodplain waters on River Murray tributari es demonstrated a heterogeneous habitat series, with ca. 500 species of mic rofauna encountered. Rotifers comprised the most diverse group (>250 taxa), however mean diversity was low (10.93 +/- 7.5), in part reflecting predati on by copepods and macroinvertebrates. Notably, only 10 rotifer species cou ld be considered widespread in the study area. Ephemeral pool microfaunal c ommunities were distinct from those of adjacent permanent billabongs; their community variability is seen as a function of, or response to, habitat he terogeneity. The significance of high species diversity in ephemeral waters is considered in the context of age of the Murray-Darling Basin, which has persisted in its present location since the breakup of Gondwana, >65 MY BP .