Ecological Responses of Algal Community to Hydrological Changes in the MacKenzie River, Australia: Implications for River Basin Management

Today, many rivers and wetlands have been heavily regulated to ensure adequate provision of water resources for anthropogenic uses. Aquatic ecosystems, especially those in arid and semi-arid regions, are experiencing severe stress due to the increasing demands on the ecosystem services they provide. In this study, samples of diatoms, soft algae and measurements of water quality were analysed at ten sampling sites for three years (between February ۲۰۱۲ and November ۲۰۱۴) along the MacKenzie River to understand the spatial and temporal variation in the relationship between algal communities, water quality and stream condition. Baseline information on algal communities and water quality was collected during base flow conditions, while experiments on the effect of water releases on algal communities were based on flow regime variations(manipulated flow regimes), specifically on the algae community structure, water quality and ecosystem function. Algal species composition changed along the river under different flow regimes and different seasons. Under base flow, diatoms were more abundant upstream and filamentous green algae were more abundant downstream. The results showed that the algal composition shifted downstream after water release events. Green algae, Cyanobacteria and Chrysophyta gradually increased from upstream to downstream under base flow conditions, and before water releases, whereas diatoms were greater upstream and increased downstream after water releases. The results suggest that by tailoring the discharge and duration of the river flows, through the amalgamation of consumptive and environmental flows would improve the condition of the stream, and supplementing the positive effects of the flows dedicated to improving environmental outcomes.

کلیدواژه ها:

Algae ، Ecology ، River management ، Biodiversity