Ecology, Evolution and Behavior

Pollution of estuaries has become a major concern in recent years because of degradation of water quality for domestic, industrial and recreational uses. Studies of pollution effects on aquatic life have taken many approaches, among these being the determination of species diversity, with a species diversity index based on one or more trophic levels used as a tool to assess adverse water quality conditions. Doudoroff and Warren (1957) stated that there was more published information on the environmental requirements of fish than on the requirements of species of any other group of aquatic organisms, with the exception of a few commercially important invertebrates. In spite of this, the use of fish as indicators of pollution has received less attention than other major plant and animal groups, microscopic and macroscopic. There are few published accounts of studies using fish diversity as a pollution indicator. The great difficulty of adequately sampling fish populations with the standard methods of collection, coupled with the great mobility of most fishes, has probably precluded the use of fish for such studies. As a part of the Texas Water Quality Board's extensive Galveston Bay pollution study, the fish populations of the bay were sampled with an otter trawl to test the thesis that fish diversity could be used as an indicator of water quality and that the fish diversity indices developed adequately represented the state of health of Galveston Bay at the time of sampling. The sampling periods were February 18 to 27, 1969; April 15 to 24, 1969; July 14 to 18, 1969; and October 14 to 17, 1969