An Australian estuary is primarily a marine-dominated environment, subjecte
d to major salinity changes only after heavy rains and during flood conditi
ons. In southeastern Australia estuarine biota are similar to those in shal
low coastal bays and some of the coastal lagoons, and most taxonomic studie
s on estuarine fauna have occurred in this region. Several major surveys of
estuarine and coastal bays have been undertaken in Australia during the pa
st three decades and these surveys have largely provided the material for t
axonomic studies of the major groups of macrobenthos. All these studies hav
e revealed a diverse and abundant benthic macrobenthos. The composition of
estuarine invertebrate fauna is compared with open exposed coasts, includin
g fauna found in soft strata and on hard strata. Australia has a limited sp
ecialized estuarine biota much of which is restricted to particular habitat
s, and a highly diverse marine community which thrives in the sheltered pro
tected waters of estuaries and the associated soft sediments. Currently, in
teractive computer-based keys are being developed which should greatly assi
st the student and the benthic ecologist to identify the fauna and prevent
potential loss of data. Some aspects of the current debate of the level of
taxonomic resolution required to answer various ecological questions are di
scussed. Finally, some comments are suggested as to future directions in wh
ich taxonomists and estuarine ecologists should proceed in order to be able
to detect changes or losses of estuarine biodiversity and the loss of the
associated biological information which may be critical in understanding th
e functioning of the estuarine ecosystem.