Document ID: chunk:federal_register_of_legislation:F2016L00043:reg:5:p8
Version: federal_register_of_legislation:F2016L00043
Segment Type: reg
Provision Reference: reg 5 (pt 8/15)
Character Range: 38834–42023

Chronic pollution may arise from both local and widespread sources. Migratory shorebirds may be exposed to chronic pollution during their time in Australia and along their migration routes, although the extent and implications of this exposure remains largely unknown. In their feeding areas, shorebirds are most at risk from bioaccumulation of human-made chemicals such as organochlorines from herbicides and pesticides and industrial waste. Agricultural, residential and catchment run-off carries excess nutrients, heavy metals, sediments and other pollutants into waterways, and eventually wetlands.

           Acute pollution

           Wetlands and intertidal habitats are threatened by acute pollution caused by, for example, oil or chemical spillage. Acute pollution generally arises from accidents, such as chemical spills from shipping, road or industrial accidents. Generally, migratory shorebirds are not directly affected by oil spills, but important habitat may be affected for many years through catastrophic loss of marine benthic food sources.

  Invasive species

  Introduced plant species such as Water hyacinth (Eichhornia crassipes), Ludwigia peruviana, Salvinia sp. and Mimosa pigra have adversely affected the ecological character and biodiversity of wetlands across Australia; introduced animals such as pigs  (Sus sp.), cane toads (Rhinella marina) and European carp (Cyprinus carpio) are also well known for their destructive impacts on wetland areas. There is also a constant risk of new introductions of exotic pasture, aquarium and garden species, such as Sea spurge (Euphorbia paralias), and exotic marine pests from ballast water and hull transport. Of specific concern for migratory shorebirds is the introduction of exotic marine pests resulting in loss of benthic food sources at important intertidal habitat (Neira et al. 2006). Predation by invasive animals, such as cats (Felix catus) and foxes (Vulpes vulpes) in Australia has not been quantified, but anecdotal evidence suggests some individuals are taken as prey.

  Outside Australia, invasive species are negatively affecting coastal habitat, causing local species to be displaced by species accidentally or deliberately introduced from other areas. With an increase in global shipping trade the influx of such species is increasing, especially in the coastal zone. Examples include Spartina grass in China, Zebra mussels (Dreissena polymorpha), and Tilapia (Tilapia spp.) in wetlands and estuaries and along coasts (MacKinnon et al. 2012).

  Altered hydrological regimes

  Altered hydrological regimes can directly and indirectly threaten migratory shorebird habitats. Water regulation, including extraction of surface and ground water (for example, diversions upstream for consumptive or agricultural use), can lead to significant changes to flow regime, water depth and water temperature. Changes to flows can lead to permanent inundation or drying down of connected wetlands, and changes to the timing, frequency
  and duration of floods. These changes affect both habitat availability and type (for example, loss of access to mudflats through permanent higher water levels, or a shift