Ecologically based targets for bioavailable (reactive) nitrogen discharge from the drainage basins of the Wet Tropics region, Great Barrier Reef. Issue 1 (15th August 2015)

• Record Type: Journal Article
• Authors: Wooldridge, Scott A.; Brodie, Jon E.; Kroon, Frederieke J.; Turner, Ryan D.R.
• Is Part Of: Marine pollution bulletin. Volume 97:Issue 1/2(2015:Aug.)
• Page Start: 262
• Page End: 272
• Publication Date: 2015-08-15
• Subjects: Water quality -- Coral bleaching -- Crown-of-thorns starfish -- Coral health -- Nutrient enrichment -- Resilience; Marine pollution -- Periodicals; Marine Biology -- Periodicals; Water Pollution -- Periodicals; Mer -- Pollution -- Périodiques; Publications périodiques; Pollution des mers; Lutte antipollution; Electronic journals; 363.7394
• DOI: 10.1016/j.marpolbul.2015.06.007
• Languages: English
• ISSNs: 0025-326X

Abstract

Highlights: A marine eutrophication indicator is modelled for variable river discharge quality. End-of-river dissolved inorganic nitrogen (DIN) reductions (%) are simulated. ∼20–40% reductions limit the risk of primary crown-of-thorns starfish outbreaks. ∼60–80% reductions are required to reverse declines in reef biodiversity. Abstract: A modelling framework is developed for the Wet Tropics region of the Great Barrier Reef that links a quantitative river discharge parameter (viz. dissolved inorganic nitrogen concentration, DIN) with an eutrophication indicator within the marine environment (viz. chlorophyll- a concentration, chl- a ). The model predicts catchment-specific levels of reduction (%) in end-of-river DIN concentrations (as a proxy for total potentially reactive nitrogen, PRN) needed to ensure compliance with chl- a 'trigger' guidelines for the ecologically distinct, but PRN-related issues of crown-of-thorns starfish (COTS) outbreaks, reef biodiversity loss, and thermal bleaching sensitivity. The results indicate that even for river basins dominated by agricultural land uses, quite modest reductions in end-of-river PRN concentrations (∼20–40%) may assist in mitigating the risk of primary COTS outbreaks from the mid-shelf reefs of the Wet Tropics. However, more significant reductions (∼60–80%) are required to halt and reverse declines in reef biodiversity, and loss of thermal bleaching resistance.