|Title||How flow and nutrients affect plants and algae in the Daly River, N.T., Riversymposium Conference, Perth 2010|
|Year of Publication||2010|
|Keywords||4: Material Budgets|
Primary production in the Daly River, a perennial tropical river in the Northern Territory, is dominated by benthic algae and periphyton, and limited in the dry season by low phosphorus and nitrogen availability. In the clear, shallow water of the river, photosynthesis exceeds biomass generation, with a significant proportion of the carbon fixed believed to be exuded as EPS. Plants observed in the river include the benthic algae, Spirogyra, Nitella and Chara, the flowering aquatic plant Vallisneria, and the emergent macrophytes, Schoenplectus. Changes in biomass of each of these groups over the course of the dry season are determined by the availability of suitable substrate, shear stress (in part, a function of flow), nutrient uptake and grazing. A numerical model incorporating these factors, driven by our observations in the river, can be used to explore how the river might respond to future changes in nutrient loads and flow. The results indicate that the river is likely to be sensitive to any increase in nutrient loads, with algal biomass increasing at the expense of more complex plants.