European colonization of New Zealand and Australia drastically altered the aquatic landscape. Development of catchments, damming of rivers, control of water levels, and the construction of reservoirs have led to a general deterioration of water quality. The water quality issues are similar to other countries, though they tend to be have arisen more recently, and organic chemical contaminants are not generally a major concern. Nutrients, cyanobacteria and pathogens are the principal water quality concerns. The first documented recording of toxicity by algae was made by George Francis in an article published in Nature in 1878. Francis noted a bloom of the toxic cyanobacte-rium Nodularia spumigena in Lake Alexandrina in South Australia (Figure 6) and the same species of alga still forms blooms in the lake today.
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