Aspects of the life history and population dynamics of Paratya australiensis
were examined in headwater streams of the Conondale Range, south-eastern
Queensland, particularly in relation to spatial and temporal variation in
temperature and flow dynamics. Breeding period and population structure at
nine sites in three subcatchments were examined during three years of monthly
sampling using a non-destructive, photographic method. Breeding was restricted
to the warmer months of late spring and summer. Peak abundances of ovigerous
females and release of larvae occurred earlier at warmer, lower-altitude sites
than at cooler, upper-altitude sites. This is consistent with the general
trend for seasonal breeding in temperate and subtropical species of atyids,
and perennial breeding in tropical species, and suggests that the summer
breeding period of P. australiensis was strongly influenced by temperature. In
subtropical, south-eastern Queensland, larvae were released just before and
during the wet season. Although populations were quite resilient, disturbance
from high-flow events also shaped the life history. Hydrology modified the
breeding period by influencing overall abundance and recruitment success and
by favouring the early release of larvae before peak flows. The reasonably
well defined seasonal cycle and synchronized development appear to result from
the combined effects of temperature and hydrology.