Pollution is mentioned as a significant pressure in most jurisdictional SoE reports, especially in relation to coastal settlements and chemical run-off from farmland into rivers and the ocean. Few generalisations can be made, because the effect varies from place to place and from situation to situation. Pollution is a contributing factor to the decline of several threatened species. Kingsford et al.89 reported, on the basis of a literature review, that pollution was a major pressure on 18% of species on the 2007 International Union for Conservation of Nature (IUCN) Red List of species (species of significance for conservation) and on 30% of species on that list that are classed as threatened.
Forms of pollution that affect marine biodiversity include sediment, nutrient and chemical run-off from agricultural and urban land; alterations to natural water temperature in waterways due to the release of colder water from dams; accumulation of plastics; discarded or lost fishing gear; and dredging and release of oil and other chemicals from commercial shipping in marine and coastal systems. Most state and territory SoE reports express most concern about urban and agricultural run-off. Carbon is also widely regarded as an atmospheric pollutant in relation to biodiversity, because it directly affects the functioning of plants and the composition of plants as food for native herbivores.
A particularly concerning emerging pollution problem is ‘micropollutants’, which include:
- chemical residues potentially affecting growth, causing birth defects and having other toxic effects on humans and other animals and plants at low concentrations92-93
- the build-up of microscopically small particles of plastics in waterways94
- nanometre-sized particles of silver, which are components of many nanotechnology products and are likely to have effects on all living organisms from microbes to vertebrates.94