Environmental research in Macquarie Harbour: interim synopsis of benthic and water column conditions

The Macquarie Harbour water column is highly stratified due to the significant freshwater inputs from the Gordon and King Rivers, deep central basin (maximum depth ~ 50m) and shallow sill at its mouth (<5 m) that restricts exchanges with the ocean. This isolation of deep waters in the Harbour has resulted in a naturally low dissolved oxygen (DO) environment (Creswell et al., 1989; Koehnken 1996). The dark tannin rich freshwater layer limits light penetration and as a consequence productivity is low; the sediments are naturally depauperate of fauna (O’Connor et al. 1996; Talman et al. 1996; Edgar et al. 1999)