|Title||Nutrients and primary production in the Flinders River|
|Year of Publication||2011|
|Authors||Faggotter, SJ, Burford, MA, Robson, BJ, Webster, I|
|Institution||Charles Darwin University|
|Keywords||chlorophyll, nitrogen, nutrient budget, phosphorus, phytoplankton, primary production, waterhole|
Dryland tropical rivers have until now been relatively little-studied, which has limited our capacity to predict how they might respond to catchment changes. Previous preliminary work in the Flinders River had raised the possibility that primary productivity in this system was not limited by light or nutrients, but by top-down control. To test this hypothesis and improve understanding of the biogeochemical and ecological functioning of Australian dryland tropical rivers, we measured water quality, primary productivity, fish and zooplankton numbers in in-channel and off-channel waterhole sites of the Flinders River (Queensland) in the early- mid- and late-dry season of 2009. We found that waterhole depth influenced water quality as well as hydrology and that phytoplankton reached a maximum biomass early in the dry season, limited by dissolved inorganic nutrient availability. Nutrient and chlorophyll concentrations increased over the course of the dry season, but this was due to evapo-concentration as waterhole volumes declined rather than to any biological effect. We found no evidence for top-down control of primary productivity in this system.