What can be the toxicity of the different pollutants on aquatic ecosystems?
The effects of pollutants on the whole organism are considered under three main headings, namely neurophysiological, behavioural and reproductive effects. These effects can often be inter-related: neurological changes can affect behaviour; changes in behaviour can affect reproduction and so on. A compound doesn’t always exert an effect on a target organism or a community. It always depends on the concentration of that compound and the time of exposure to it. These effects eventually can be either acute or chronic. Acute toxicity occurs rapidly, are clearly defined, often fatal and rarely reversible. Chronic effects develop after long exposure to low doses or long after exposure and may ultimately cause death. A poison is lethal when it causes death, or sufficient to cause it, by direct action. And it is sub lethal when the poison is below the level that directly causes death. Then it results in the regression of the physiological or behavioural processes of the organism, and its overal
