Baseline surveys and metal binding proteins as metal pollution indicators

Doctoral Thesis


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University of Cape Town

The field of metal determination as a part of pollution studies, has been critically examined and metal pollution may be defined in one simple statement: The presence of metal binding proteins confirms toxic metal pollution. It has been shown that current methods of metal determination in biological systems are of little use. This has been illustrated by both a review of metal concentration in Southern African coastal water, sediments and biotopes, and by a comparative baseline study of organisms from Gough Island and Mar ion Island. These showed that extrapolation of results from one geographical area to another are invalid and that this interpretation is made difficult by factors such as age, sex, size life stage of the organisms. Furthermore, it was shown that many reports on metal pollution do not even mention fundamental information such as the size or the sex of the animals. Metal pollution could be linked to metal binding protein through an independent pollution er i ter ia, for example, the out of season moulting of crayfish. The new definition of metal pollution has then been tested by application to five different organisms (crayfish, Jasus lalandii; hermit crab, Diogenes brevirostris; shrimp, Palaemon pacificus; black mussel, Choromytilus meridionalis and limpet, Patella granularis) kept under identical conditions and it was shown that a much more meaningful interpretation of the results could be made. The new definition was al so tested with two naturally occurring metal accumulating organisms (whelk, Bullia digitalis and "kikuyu" grass) and it was shown that dramatic increases in metal may not necessarily be toxic. It was concluded that less effort and time should be spent on metal analysis in determination of metal pollution and attention should rather be directed to the presence or absence of metal-binding proteins.

Bibliography: pages 304-309.