Fresh waters and estuaries of the Great Barrier Reef catchment: Effects and management of anthropogenic disturbance on biodiversity, ecology and connectivity

Highlights: • GBR catchment waterways provide key ecosystem services and have high biodiversity. • Both are threatened by the impacts of development and land use. • Threats: sediment, nutrients, hypoxia, alien species, pesticides, barriers, climate • Effects: loss of habitat, connectivity, endemic species, ecosystem function • Integrated management of freshwater, estuarine and marine systems is required. We review the literature on the ecology, connectivity, human impacts and management of freshwater and estuarine systems in the Great Barrier Reef catchment (424,000 km²), on the Australian east coast. The catchment has high biodiversity, with substantial endemicity (e.g., lungfish). Freshwater and estuarine ecosystems are closely linked to the land and are affected by human disturbance, including climate change, flow management, land clearing, habitat damage, weed invasion, and excessive sediments, nutrients and pesticides. They require holistic integrated management of impacts, interactions, and land-sea linkages. This requirement is additional to land management aimed at reducing pollutant delivery to reef waters. Despite advances in research and management over recent decades, there are substantial deficiencies that need addressing, including understanding of physical and biological processes and impacts in ground waters, large rivers and estuaries; ecological effects of pesticides; management and mitigation for invasive species and climate change; and explicit protection of non-marine waters.