The effects of river regulation and response of invertebrates to a pulse flow release in the upper Hunter Catchment, NSW

Abstract

The deleterious effects of river regulation have been well-documented in rivers worldwide. Although river regulation affects physio-chemical parameters, invertebrate density, richness, community composition and interactions within food webs, these impacts are not always consistent. Restoration of components of natural flow regimes may be beneficial in recovering the ecological integrity of riverine ecosystems. However, the mechanisms are unclear and rigorous testing of the effects of pulsed flow releases has rarely occurred. This thesis aimed firstly to document the effects of river regulation on physio-chemical attributes and invertebrate communities and then test the response to a pulsed flow release. It was hypothesised that regulated rivers would have fewer invertebrate taxa, higher density, altered community composition and increased contribution of autochthonous sources to their diets. A pulsed flow release was hypothesised to decrease the density of invertebrates positively affected by regulation, alter the community composition to more closely resemble that of an unregulated river and increase the contribution of allochthonous sources to their diets. The study was conducted in the upper Hunter Catchment in north-eastern New South Wales, Australia.