Pollution issues affecting biodiversity in Australia can generally be categorised as relatively local in nature (e.g. specific waste streams from poorly managed activities or legacy sources in groundwater, such as plumes under industrial sites) or relating to broad landscape processes (e.g. nutrient enrichment in the Great Barrier Reef from farming or inappropriate pesticide use). The Coasts report describes impacts from pollution on coastal ecosystems in Australia. Common contaminants found in coastal rivers and estuaries around Australia include metals, pesticides, herbicides, terrigenous sediments and debris (predominantly plastics). The current state of coastal river and estuary pollution is poor, and has been deteriorating since 2011. Nationally, pollution pressure on many coastal waters is moderate to strong, but varies greatly among waterways. In the eastern states, pollution is most intense in more developed estuaries, although overall pressures appear to be moderate.
Perhaps the largest pollution issue of concern for biodiversity in Australia that has risen in prominence during the past 5 years is marine debris and ingestion of plastics by marine animals. The Coasts and Marine environment reports both describe the impact of marine debris on coastal and marine fauna. Debris may directly entangle fauna, such as in the Gulf of Carpentaria where an estimated 5000–15,000 turtles become ensnared in discarded fishing nets each year. Shorebirds, turtles and invertebrates may ingest and accumulate plastics. The ecological effects of microplastics are largely unknown, but include bioaccumulation of toxins, which potentially transfer up the food chain and enter human diets. Four states and territories have banned single-use plastic bags in the past 7 years (South Australia—2009, the Australian Capital Territory—2011, the Northern Territory—2011 and Tasmania—2013) as a direct measure to decrease impacts on marine life.
Although global concern regarding micropollutants has increased during the past 5 years, micropollutants have not yet been formally recognised as a threat to Australian marine fauna. Pesticides used to spray insect pests, such as fenitrothion for locust plagues, has an impact on some species. Of serious concern is the cumulative impact of many threats, including the impact of pesticides on the plains-wanderer (Pedionomus torquatus) in southern Australia. The National recovery plan for the plains-wanderer (DoE & DEWNR 2016) reports that the actual impact of pesticides is unknown, but that the concentration of fenitrothion that is used for spraying can kill birds that come in contact with the chemical.
Several Queensland rivers and estuaries have recorded moderate to strong environmental impacts of sediments and pesticides. A report card system is in place for south-east Queensland, Gladstone Harbour, the Great Barrier Reef and Mackay. However, monitoring has shown little improvement in water quality in the past 5 years, which can be explained by the scale of the problem, and the necessary transition and cost of agricultural reform.