Ecological investigations of a disturbed Texas coastal estuary.

Rollover Pass, a cut through Bolivar Penisula on the Gulf coast of eastern Texas, was constructed in January 1955, and introduced Gulf waters of high salinity into the upper portion of East Bay. The present study was concerned with ascertaining what changes occurred in the physical, chemical, and the biological charisteristies of the bay following the excavation of the pass. A nearly two-fold increase in salinity from 1954 to 1955 was detected in the upper region of the bay. Temperatures were comparable for the two years, but turbidity was slightly greater in the upper bay in 1955 than in 1954. The number of species of fishes in 1955 (51 forms) was nearly the same as for 1954 (50 species). However, nine forms recorded in 1954 were not noted in 1955. Ten species were found in 1955 which were not caught in 1954, and some of these were salt-loving species whose presence reflected the increased salinity in the bay. Most of the fish population mass in 1955 was composed of the same species which made up the bulk of the catch in 1954. Noticeable increases in the catches of menhaden and anchovy were recorded, while the relative abundance of young croaker and spot appeated to be less in 1955 than in 1954. The proportions of the various species in the 1955 catch varied also from those of 1954. Three species of shrimps were found in the bay during 1955. The brown shrimp was less abundant and the white shrimp more abundant than in 1954. The sea bob, not caught in 1954, was taken in 1955.