Decapod Crustacean Communities in Texas Seagrasses




Penn, Gary J.

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University of Houston


An investigation of the decapod fauna in eight seagrass beds along the Texas coast reveals three distinct communities. The seagrass Halodule has two communities, separable geographically into northern and southern components, and the seagrass Thalassia contains the third community. These communities differ in abundance of individuals, number of species, diversity, dominant species and characteristic species. Additionally, the northern-most Halodule grassbeds demonstrate seasonal changes in the dominant species over time. The grassbeds in the southern portion of Texas' coastline maintain a constant proportional distribution of species. Factor analysis is employed to reduce 26 environmental parameters to a few factors. The abundance of a given species is regressed against factor scores for the collections to determine which environmental parameter(s) are significantly related to that species' abundance. Most species are found to be related to the standing crop of seagrasses and/or a substrate factor if burrowing. Based on these relationships, the factor limiting populations appears to be space. The grassbeds appear to be trophically rich thus eliminating food as a limiting factor. Physico-chemical parameters such as temperature and salinity were not found to be significantly related to species abundance. An investigation of the reproductive strategies of Palaemonetes congeners indicates that P. vulgaris is more fecund than P. pugio, probably because of differential predation pressures. The differences in community structure and the relationships of individual species to the standing crop of seagrasses indicate that seagrass beds are a vital aspect of the estuarine ecosystem and are an important element to be considered in any estuarine management program.


126 pages


crustaceans, aquatic communities, sea grass, decapods