TRaCK: Tropical Rivers and Coastal Knowledge

Science and knowledge that governments, communities, industries for sustainable use of Australia's tropical rivers and estuaries

Effect of sewage nutrients on algal production, biomass and pigments in tropical tidal creeks

TitleEffect of sewage nutrients on algal production, biomass and pigments in tropical tidal creeks
Publication TypeJournal Article
Year of Publication2012
AuthorsBurford, MA, Revill, AT, Smith, J, Clementson, L
JournalMarine Pollution Bulletin
Start Page2671
Date Published12/2012
KeywordsPhytoplankton; Benthic microalgae; Microphytobenthos; Sewage markers; Coprostanol; Nitrogen

Microalgal blooms can result from anthropogenic nutrient loadings in coastal ecosystems. However, differentiating sources of nutrients remains a challenge. The response of phytoplankton and benthic microalgae (BMA) to nutrient loads was compared across tropical tidal creeks with and without secondary treated sewage. Primary productivity in the water column was limited by nitrogen availability in absence of sewage, with nitrogen saturation in the presence of sewage. Phytoplankton primary productivity rates and chlorophyll a concentrations increased in response to sewage, and there was a greater response than for BMA. There was no change in algal pigment proportions within the phytoplankton or BMA communities. Concentrations of the sewage marker, coprostanol, were higher near sewage discharge points decreasing downstream, correlating with a decline in nutrient concentrations. This suggests that sewage was the main source of nitrogen and phosphorus. This study highlights the scale and type of response of algal communities to sewage nutrients.