ABSTRACT
In reviewing the differences between temperate and tropical organisms and their implications for aquatic pollution management, a useful starting point is to describe the biophysical conditions of tropical and temperate zones. At one extreme, ice crystals disrupt cells and terminate metabolic activity, while at the other, high temperatures impair physiological integration, inactivate enzymes, alter the cytoplasm, and lead to behavioral changes. The high water temperatures of the tropics are also to be found in transitional regimes of the subtropical zone. For any organism, no matter how precise its acclimation mechanisms, there are eventual limits, so that all organisms are constrained by environmental temperature in some way. To measure the temperature tolerance of organisms, the concept of critical thermal maximum and minimum was introduced, although subsequently modified. Temperature tolerance also may differ in different stages in the life cycle of the particular organism. Temperature tolerances in invertebrates also are related to thermal history, whether in the laboratory or in the field.
