Document ID: chunk:federal_register_of_legislation:F2019L00106:body:0:p54
Version: federal_register_of_legislation:F2019L00106
Segment Type: other
Provision Reference: 
Character Range: 144232–147120

River is likely to have been removed (along with all other fish species) through heavy metal contamination from the collapses of the Captains Flat Mine tailings dam between the 1930s–1940s (Lintermans 2002).
Pollution has the potential to affect all aspects of the life history of the Macquarie perch. Of particular concern are endocrine disrupting chemicals such as pesticides, sewage effluent and plasticisers. The most prominent effect of endocrine disruption in fish is in the reproductive system affecting gonaopodium development, demonstrated in fish such as eastern gambusia (Batty & Lim 1999; Pait & Nelson 2002). The introduction of chemicals and biodegradable material to water has obvious effects on fish, depleting dissolved oxygen levels resulting in fish kills. From what is known of fish at a similar trophic level a healthy level of dissolved oxygen for Macquarie perch would be in the order of 7.5 mg/L and above (Davis & Cornwell 2008). Fish kills for Macquarie perch were reported from Hughes Creek in Autumn 2009 when dissolved oxygen dropped below 3 mg/L as a result of low flows and other poor water quality factors (Kearns 2009, cited in ARI pers. comm., 2017).
Poor water quality is also likely to affect Macquarie perch feeding, breeding and migration. Poor water quality is likely to lead to a lowered immune system in fish making them susceptible to disease (see also section 6.2.5). There are also many effects on the fish that may be unknown such as the bio-accumulation of fat-soluble chemicals. Poor water quality is also likely to limit the expansion of Macquarie perch into other areas.

6.2.8 Climate change
Freshwater environments, and the organisms that inhabitat them, are particularly vulnerable to climate change because they are isolated and fragmented within a terrestrial landscape (Morrongiello et al., 2011). Surface water, which determines the quality and availability of aquatic habitat depends heavily on rainfall and temperature regimes which will drastically change under climate change predictions (Carpenter et al., 1992; Hobday & Lough 2011). Climate change projections for the Murray-Darling Basin predict increases in temperature and evaporation and less rainfall and snowfall, which will likely result in reduced runoff to rivers and wetlands especially in the southern Basin (CSIRO 2008; Dunlop & Brown 2008; Morongiello et al., 2011). Median runoff is predicted to decline by up to 12 per cent and flood frequency is predicted to decrease (Balcombe et al., 2011). However, extreme events such as storms (and associated floods) and droughts are projected to rise in frequency and/or intensity under climate change (Aldous et al., 2011; Hobday & Lough 2011). As are extreme fire weather events, with the resultant greater risks of secondary water pollution and sedimentation (Morongiello et al., 2011).
Tonkin et al. (2017b) suggests