Abundance, distribution, and injury of four decapod crustaceans collected from the Dickinson Bayou and Bay and the revolving screens, intake and discharge canals of the P.H. Robinson Generating Station.
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Four species of commercially important decapod crustaceans collected in the intake area and discharge canal of the P.H. Robinson Generating Station were studied for 13 months. Salinity did not seem to have a great deal to do with abundance of the shrimps Penaeus aztecus and P. setiferus, or the blue crab, Callinectes sapidus. C. similis, on the other hand, although taken at fairly low salinities, seemed to prefer salinities near 15 ppt and higher and their presence in the collecting area was related to changes in salinity. Temperature had a definite affect on abundance in the discharge and intake canals. Maximum summer temperatures in the discharge canal appeared to be lethal. As temperatures approached 40 C, fewer animals were collected from the discharge canal than in the intake canal. The reverse occurred during the winter when temperatures dropped to below 18 C. When temperatures were low in the intake canal, numbers of crustaceans in the discharge canal were usually higher than in the intake canal. Although individuals of P. aztecus, P. setiferus, and C. sapidus were present during the entire study, there were definite annual cycles in abundance. P. aztecus increased in the collections in April and left in September. P. setiferus moved in during late July and left during November. C. sapidus were present throughout the year in larger numbers than the shrimp but the majority were taken from April through October. C. similis probably has a similar cyclic nature but because of the low salinities in the collecting area during the first part of the study, they did not move up into the bay. When salinities increased in July and August, they moved into the area. They began moving out in late October. Injury to crustaceans resulted from both plant operations and techniques used in conducting the research. This prevented a true assessment of plant related damage. Plant related injury was much lower than total injury recorded.