FISHERY BULLETIN: VOL. 82, NO. 2 



and reliability of our analyses were improved over 

 previous studies. 



METHODS 



Study Site 



A salt marsh on the West Bay side of Galveston 

 Island was selected as the study site (Fig. 1). The 

 marsh extended into the island for about 2.5 km, 

 allowing tidal circulation throughout numerous 

 coves and bayous. The intertidal marsh was domi- 

 nated by vegetation, S. alterniflora , and the sub- 

 tidal was not vegetated. Water depth was gener- 



ally <1 m, but subtidal bottom was always 10 to 20 

 cm deeper than adjacent intertidal vegetation. 

 Vegetation occurred in irregular patches, creating 

 a reticulated effect on marsh macrostructure, and 

 occupied about 25% of the area (Fig. 2). 



Experimental Design 



A paired sampling design was employed to com- 

 pare shrimp densities between marsh habitats. 

 Each sample pair consisted of one sample taken in 

 vegetated habitat and another in adjacent non- 

 vegetated habitat as close as practically possible. 



Sampling was scheduled to coincide with the 



GALVESTON BAY 



SALT MARSH 

 STUDY SITE 



OUTER ZONE 



MIDDLE ZONE 



INNER ZONE 



H 



3 "ARSH 

 C3 "ATER 



94°58'W 

 29°12N 



To City of Galveston 



u L F OF MEXICO 



FIGURE 1.— Galveston Island State Park showing the salt marsh study site in Carancahua Cove fronting Galveston West Bay. (Redrav 



from Texas Parks and Wildlife Leaflet 4000-42.) 



FIGURE 2. — Upper: Reticulation between vegetated and non- 

 vegetated habitats in a salt marsh on Galveston Island. Areal 

 view at about 500 ft altitude. Lower: Stands of intertidal Spar- 

 tina alterniflora and adjacent subtidal nonvegetated bottom in a 

 salt marsh at Galveston Island State Park. 



326 



