Shancho et al, 2010). Dead zones are now thought to affect more than 245 000 km2 of marine ecosystems, predominantly in the northern hemisphere (Diaz and Rosenberg, 2008), equivalent to the total global area of coral reefs.

Toxicity, saphrogens and mutagens A wide range of toxic pollutants from land based sources are found in both fresh and marine waters ranging from agricul- tural and industrial chemicals such as organic compounds, heavy metals to personal-care products and pharmaceuticals. The impacts of these are wide-ranging. In the north east of Australia, run-off of agricultural herbicides caused the loss of 30 km2 of mangrove between 1999 and 2002. In areas where mangroves were lost, the near shore zone suffered greater tur- bidity, nutrient loading and sediment loading as well as greater

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