Macroinvertebrate community succession under variable flow regimes in subtropical Australia

Abstract

Seasonal changes in hydrology are important factors influencing abiotic conditions and subsequently the biota. Although these effects have been studied in tropical catchments and in central arid Australia, subtropical ephemeral streams have largely been ignored. In the present study, three ephemeral streams in Central Queensland were monitored over 15 months. We hypothesised that macroinvertebrate abundance would increase gradually following the initial flow pulse and that abundance would increase until the pools began drying, with sensitive taxa only present during higher flow. In all, 69 families from 14 orders were collected in 128 samples. Significant relationships were not detected between low flow conditions and taxa richness (P > 0.05). Principal component analysis showed that the macroinvertebrate communities did not change in response to the drying of pools. Significant differences were not observed between taxa richness, abundance nor tolerant taxa during varied periods of flow (P > 0.05). Sensitive taxa were most abundant during high-flow periods with comparatively less abundance during no flow and drying periods. This study provides novel information on the flow-linked succession of macroinvertebrate communities in subtropical ephemeral streams and the results are important in informing the development of riverine indices and models used to manage subtropical environments