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
.