ABSTRACT

Although there is much evidence to point to the presence of pollutants/toxicants in the aquatic environment, the link to incidences of ‘disease’ is often unclear. The situation is not helped by confusion among individuals about the precise meaning of the term disease. Therefore, mortalities in animals and plants resulting from a chronic discharge of pollutants do not necessarily conjure up the image of a disease situation. Conversely, an infection caused by bacteria or viruses would fulfill most individuals’ notion of a disease. However, it would be pertinent to enquire whether or not long-term damage to an organism resulting from chronic discharges of noxious material would be regarded as disease. A complication is that the damage might well occur long after the pollutant has been removed from the vicinity of the aquatic organism. Therefore, proof of cause and effect may be notoriously difficult to acquire. In addition, it should be emphasised that where a choice exists motile organisms are likely to move away from polluted areas.