Population Dynamics and Life History of Paratya australiensis Kemp, 1917 (Decapoda:Atyidae) in Upland Rainforest Streams, South-Eastern Queensland, Australia

Abstract

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.