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

Abstract

This paper surveys the biology of central Amazonian fishes and the physicochemical conditions 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 by the annual flood cycle and is characterized by high temperatures and widespread hypoxia. Important differences exist among habitats in the absolute levels and degree of dairy and seasonal variation in temperature and oxygen supply.Air-breathing fishes are numerous and diverse in comparison with other types of aquatic environment, but make up only a small proportion of the total fauna, even in the more hypoxic habitats. Many other species use the oxygenated surface layers for branchial respiration. The potential interrelationships between respiratory strategies and other aspects of the species biology such as feeding niche, habitat type, aniipredator strategies, and capability of overland movement s are discussed.