Environmental Water Requirements of Vallisneria nana in the Daly River, Northern Territory

N. Rea, P. Dostine, P. Cook, I. Webster and D. Williams
Department of Infrastructure, Planning and Environment, Repo2t 35/2002

This project focuses on the major riverine plant, Vallisneria nana R.Br., beds of which are a keystone habitat. Macrophytes play a role in providing food, breeding sites and refuge for animals, and in the cycling of nutrients, metals and carbon. They slow currents, trap organic matter, sediments and nutrients, reduce turbidity, stabilise banks, increase shade and reduce water temperatures. Vallisneria species were once considerably abundant in the regulated inland rivers of south-eastern Australia. Their loss is attributed to adverse changes in water quality and flow. The loss of V. nana would cause a cascade of adverse changes across the food web. The overall project objective was to make recommendations about the environmental conditions needed to sustain V. nana and its functional role in the Daly River.