Monitoring water quality and coral reefs adjacent to Douglas Shire

Bordering the Great Barrier Reef (GBR), Douglas Shire has well-developed coral reefs at several locations along its coast. These reefs are particularly at risk from changes in water quality due to land use practices in adjacent catchments.

AIMS contributed to the Douglas Shire Water Quality Improvement Project (WQIP) in 2005 by producing a baseline description of coral reefs and water quality in the Shire’s coastal waters. AIMS been undertaking surveys of regional reefs since 1985 and twice-yearly surveys of water quality off Douglas Shire and Cairns since 1989, the longest and most comprehensive monitoring of water quality in GBR coastal waters.

The waters of the GBR lagoon that border Douglas Shire are generally characterised by low concentrations of dissolved nutrients, phytoplankton biomass and suspended particulate matter, conditions that favour the establishment and growth of coral reefs. During the monitoring period, phytoplankton biomass and nutrient concentration remained low, with small increases in suspended sediment, dissolved organic nitrogen and phosphorus.

Similar results were observed for near-shore and off-shore reefs. In-shore reefs are more at risk from episodic disturbances including increases in nutrients, suspended sediments and pesticides, as well as low salinity seen during the wet season, but also coral bleaching and cyclonic waves. In these areas the dominant coral and algae species are either naturally adapted to survive these events or quickly recolonise. There is no evidence that observed levels and variability in suspended sediment and nutrients impeded normal reef processes.

March 6, 2008