Waterloo Bay received a “D+” grade in the 2009 Report Card (previously “A”), the largest reduction in grade for any zone within Moreton Bay indicating a major deterioration in ecosystem health.  This decline in grade was due to a combination of factors with the most important being increases in the sewage nitrogen signal (δ¹⁵N), increased phytoplankton abundance (Chl-a) and to a lesser extent reduced water clarity (Secchi depth).  Lyngbya also occurred within the zone in 2008/2009 whereas it was not previously monitored from Waterloo Bay in 2007/2008.  However, the zone remained 99% compliant for nutrient concentrations (TN) and the seagrass extent and depth range remained good and relatively stable.  There was only a slight reduction in coral density observed (seagrass distribution, seagrass depth range and coral cover being the three BHR indicators for the bay zones).

Waterloo Bay is assessed against a Western Embayment guideline along with Bramble and Deception Bays. As much of Waterloo Bay is considered of high ecological value due to the presence of relatively stable and diverse seagrass meadows and coral communities, its water quality conditions have previously provided the reference condition used for the Western Embayment guideline.

Abbreviations glossary

A description of the indicators and methods used can be downloaded as a PDF file.

ECOSYSTEM HEALTH INDEX (EHI)

The EHI is a measure of the proportion of a reporting zone that complied with the water quality objectives for key indicators monitored as part of the Ecosystem Health Monitoring Program. The water quality objectives are defined in the South East Queensland Regional Water Quality Management Strategy (2001).

• EHI 1 = 100% of area complies with the environmental objectives.
• EHI 0 = 0% of the area complies with the environmental objectives.

BIOLOGICAL HEALTH RATING (BHR)

The BHR forms 20% of the the Report Card Grade. The values in this sheets are calculated using the original method used since 2002-03 and is presented for comparison.