ABUNDANCE OF MACROCRUSTACEANS IN A NATURAL MARSH AND 

 A MARSH ALTERED BY DREDGING, BULKHEADING, AND FILLING^ 



Lee Trent,2 Edward J. Pullen,^ and Raphael Proctor^ 



ABSTRACT 



Indices of abundance of macrocrustaceans during March-October 1969 in West Bay, Tex., were 

 determined for day and night and statistically compared between 1) a natural marsh area, 2) upland 

 and bayward canal areas of a housing development, and 3 ) an open bay area. Significance levels of 5% or 

 1% were used in the statistical comparisons. Catches of brown shrimp, Penaeus aztecus; white shrimp, 

 P. setiferus;h\ue crab, Callinectes sapidus;and pink shrimp, P. duorarum, were significantly greater at 

 night than during the day at one or more stations in the marsh. More grass shrimp, Palaemonetes sp., 

 were caught at night than during the day, but the differences were not statistically significant. 

 Individuals of each species appeared to migrate into the more shallow areas of the marsh at night. At 

 night, brown shrimp and blue crabs were significantly more abundant in the marsh and bayward canal 

 areas than in the upland canal and bay areas, white shrimp were significantly more abundant in the 

 marsh area than in the other three areas, and pink shrimp were significantly more abundant in the 

 marsh than in the upland and bayward canal areas. During the day, brown shrimp were significantly 

 more abundant in the bayward canal area than in the upland canal and bay areas, while pink shrimp 

 were significantly more abundant in the marsh area than in the upland canal area. The generally lower 

 catches of each species in the open bay and upland canal areas when compared with the marsh and 

 bayward canal areas were attributed to: 1 ) permanent loss of intertidal vegetation in the housing 

 development; 2) low abundance of detrital material and benthic macroinvertebrates in the open bay 

 and upland canal areas; and 3) eutrophic conditions in the upland canal area. 



Development of bayshore property into housing 

 sites by dredging, bulkheading, and filling is oc- 

 curring in many estuaries. When this property is 

 developed, shallow bay and tidal marsh areas are 

 often dredged or filled with spoil, thus changing 

 the environment for marine organisms. Informa- 

 tion is available on some of the environmental 

 changes that are critical, but the effects of these 

 changes on the abundance of macrocrustaceans in 

 Gulf coast estuaries are poorly known. 



Ecological studies conducted by personnel of the 

 National Marine Fisheries Service in the Jamaica 

 Beach housing development in West Bay, Tex., 

 during 1969 were reported by Trent et al. (1972). 

 That report described the study area and included 

 summary information on phytoplankton produc- 

 tion, oyster production, benthic organisms, sedi- 

 ments, hydrology, and the abundance of macro- 

 crustaceans and fishes. Detailed analyses were 

 reported by Corliss and Trent (1971) on phyto- 



iContribution No. 398, Gulf Coastal Fisheries Center, Na- 

 tional Marine Fisheries Service, NOAA, Galveston, TX 77550. 



^Present Address: Gulf Coastal Fisheries Center Panama City 

 Beach Laboratory, NMFS, NOAA, Panama City, FL 32401. 



^Present address: Department of the Army, U.S. Corps of En- 

 gineers, Galveston, TX 77550. 



Manuscript accepted April 1975. 



FISHERY BULLETIN: VOL. 74, NO. 1, 1976. 



plankton production, Moore and Trent (1971) on 

 oyster production, and Gilmore and Trent (1974) 

 on benthic organisms and sediments. 



Mock (1966) studied the abundance of brown 

 shrimp, Penaeus aztecus, and white shrimp, P. 

 setiferus, in Galveston Bay, Tex., after the 

 bayshore was altered by bulkheading. He stated 

 that catches of brown shrimp were 2.5 times 

 greater, and catches of white shrimp were 14 

 times greater in a natural habitat than in a bulk- 

 head area. 



The objectives of this study in the Jamaica 

 Beach area during 1969 were to evaluate relative 

 abundance of selected macrocrustaceans be- 

 tween: 1) day and night; 2) housing development 

 canals, natural marsh areas, and open bay areas; 

 and 3) areas with different concentrations of dis- 

 solved oxygen. 



STUDY AREA AND METHODS 



The study area, located in West Bay, included a 

 natural marsh area, an open bay area, and a 

 canal area. The canal area was similar to the 

 natural marsh before it was altered by channeli- 

 zation, bulkheading, and filling (Figure 1). The 

 altered area, which included, prior to alteration, 



195 



