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45
Shancho
et al
, 2010). Dead zones are now thought to affect
more than 245 000 km
2
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 km
2
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