Organisms exposed to pollutants often develop subtle cellular differences and may accumulate certain toxicants. The assessment of body burdens of pollutants in key ecosystem indicator organisms can provide a sensitive, early warning of the presence of pollutants. Extensive surveys of inshore Queensland crab pollutant concentrations have demonstrated this type of organism as a useful monitoring vehicle to use to assess changes in pesticide concentrations in nearshore marine biota. This program will be augmented by new methodologies as they become routinely available. Outcomes: Information about current status and long-term (10 year) trends in water quality and marine ecosystem status in the GBRWHA.