Habitat availability and utilization by benthos and nekton in Hall's Lake and west Galveston bay.
Webb, J.W., Jr.
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Salt marsh habitats along the shoreline of Hall's Lake are threatened by wave erosion, but the reconstruction of barrier islands to reduce this erosion will modify or destroy nonvegetated habitats in West Bay. In order to provide information on the relative value of these estuarine habitats for fishery species, we identified the habitats present and sampled vegetation, sediments, and benthic and nektonic organisms in May 1990. In comparison with nonvegetated bottom, Spartina alterniflora marshes had higher sediment organic content and densities of infaunal crustacea, Macrocrustacea (brown shrimp, grass shrimp, and blue crabs), and pinfish. Nonvegetated sites had greater numbers of forage fish such as anchovies. Both trawls and drop samples were used to sample nonvegetated bottom, and there appeared to be little difference among the nonvegetated sites. Mean densities of animals collected in trawls, however, were less than 50% of densities measured with the drop sampler. The value of salt marsh habitats for estuarine animals varied, and within Hall's Lake there was a significant correlation between marsh elevation and density of most macrofauna. In addition, densities of brown shrimp and pinfish were significantly greater in the well-established marshes of Hall's Lake compared with the narrow intermittent marsh present along the West Bay shoreline. Conclusions on relative habitat value based on samples collected at one point in time can be misleading, but data from historical samples, collected in the Hall's lake marsh, suggest that densities of macrofauna observed in our study are not anomalous. In conjunction with other published data on habitat value in Galveston Bay, our results indicate that for most crustacea the Hall's Lake marshes are more valuable than the other habitats examined. The relative value of the habitats for fishes was highly dependent upon the species. A survey of the West Bay shoreline indicated that valuable salt marsh habitats could be established on created barrier islands if direction of exposure and shoreline slope were controlled.