Water quality in the Great Barrier Reef World Heritage Area: Past perspectives, current issues and new research directions

Elevated sediment and nutrient concentrations have long been regarded as th e pre-eminent water quality threats to the Great Barrier Reef,,vith the pot ential risk posed by other pollutants such as heavy metals, persistent chlo rohydrocarbons, PCBs and petroleum related compounds considered to be of le sser consequence. However, the management focus on these latter types of po llutants has recently shifted to acknowledge the potential impact posed by diuron, dioxins, dieldrin, and mercury and cadmium concentrations detected in sediments and biota along the Great Barrier Reef and southern Queensland coastline. In general, these threats originate from areas dominated by int ensive cropping agriculture and are exacerbated by high rainfall and erosio n rates in the wet tropics region of the Queensland coast. Maintenance of l ong-term monitoring programmes, which utilize innovative data acquisition t echniques will enable assessment of change in environmentally relevant poll utant concentrations over time. However, improved land management practices , which include an immediate minimization of vegetation clearance and respo nsible use of pesticides and fertilizers in Queensland are essential if wat er quality in the Great Barrier Reef World Heritage Area is to be maintaine d and protected. (C) 2000 Elsevier Science Ltd. All rights reserved.