The fishes and the aquatic environment of the central Amazon basin, with particular reference to respiratory patterns

This paper surveys the biology of central Amazonian fishes and the physicochemical condi- tions of their habitats, with particular emphasis on factors related to respiration, in order to place in an ecological perspective the studies of respiratory physiology carried out on the 1976 Alpha Helix Amazon Expedition.
The environment is strongly influenced hy the annual flood cycle and is characterized by high temper,Ilures and widespread hvnoxia. Important differences exisr arnona habitars in thc absolute
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levels and degree of daiiy and searonal variation in lernpcrature and oxvfen supply. Air-breathing fishes are nurnerotls and d~versein comparison with other types of aquatic environment, hut make u p only a small proportion of rhe total Fauna, even rn the more hypoxic hahirats. Many other s p c i e s use the oxvgenated surface lavers Tor brunchial respiration. The potential intelrelarionshipr hetween respiratory stralegies and other aspects of the species
binlcigy such as feeding niche. habitat type, nn~ipredarorstwtegiex. ant1 capability of overland movements ar?:discus&.