Species composition, distribution, and abundance of macrobenthic organisms in the intake and discharge areas before and after the construction and operation of the Cedar Bayou Electric Power Station.




McBee, J.T., Jr.

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Texas A&M University.


The species composition, distribution, and abundance of macrobenthic organisms in the intake and discharge areas of the Cedar Bayou Electric Power Station, Baytown, Texas, were investigated using data obtained from October 1969 through May 1973. Two types of quantitative bottom sampling devices were used; a modified Birge-Ekman dredge (16 stations) and a frame sampler (5 stations). Each gear was used every 4 weeks, but alternately; with a 2-week time interval between use of the dredge and frame. Data from each gear type were treated separately. Hydrological measurements including water temperature, dissolved oxygen, and conductivity accompanied each biological sample. Data were analyzed using cluster analysis. Because the plant was off-line during most of the summer of 1971 and a cooling pond was in operation during the following summer, little elevation of temperature occurred in the discharge area of Trinity Bay. Bottom salinities were usually higher in the discharge area than in the surrounding water. Changes in species composition, distribution, and abundance determined by cluster analysis were correlated with natural and plant-induced changes in the ecosystem. Periods of relatively low and high salinity in 1970 and 1971, respectively were related to abundance and frequency of occurrence of some species. Littoridina sphinctostoma, Odostomia barretti, and Vioscalba louisianae were most abundant in 1970 and were absent or taken infrequently during 1971 while Glycinde solitaria, Eteone heteropoda, Heteromastus filiformis, and Mulinia lateralis were most abundant in 1971 and absent or infrequently taken during 1970. The only effect of the plant in the discharge area was a change in species composition associated with scouring of the substrate by the discharge effluent. The abundance of Neanthes succines, Polydora ligni, Polydora websteri, Leptochelia dubia, and gammarid amphipods increased at that location. A change in Cedar Bayou below the plant intake was related to the removal of low quality water and the ingress of bottom organisms created by the reversed flow in the bayou. A slight increase in abundance of Mediomastus californiensis, Macoma mithcelli, Streblospio benedicti, and Rhynchocoel #1 in lower Cedar Bayou corresponded to the pumping of cooling water by the plant.


205 p., Dissertation


power plants, benthic environment, dredged samples, temperature effects, salinity effects, benthos, ecological distribution, thermal pollution, abundance, cooling water, sampling, check lists