The use of Juncus and Spartina marshes by fisheries species in Lavaca Bay, Texas, with reference to effects of floods
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The use of Juncus and Spartina marshes by fisheries species in Lavaca Bay, Texas, with reference to effects of floods
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    "Coastal Spartina marshes, deltaic Juncus marshes, and subtidal bottom without vegetation in Lavaca Bay were compared for usage by aquatic fauna. Faunal densities were measured using drop trap sampling methodology at coast and delta locations during spring, summer and fall seasons, in salinities that ranged from 13 to 30 ppt (mesohaline and polyhaline regimes). In general, the coast and delta habitats were used similarly. The same species were abundant in both areas. In particular, densities of penaeid shrimps, blue crab and economically important fishes were usually not significantly different between coast and delta habitats. Within locations abundances were usually significantly higher in marsh as compared to bare subtidal habitat. Variations in distributions and abundances were attributed more to seasonal differences in tidal inundation patterns than to coastal or deltaic locations. In a related study, the effect of freshwater flooding on utilization of delta marshes was examined. Animal densities before and after three floods occurring between the fall of 1986 and the spring of 1987 were compared. After the first two floods (October 1986 and May 1987), salinities returned to background levels within a week. After the third flood, in late May and early June 1987, background salinities of 5 to 8 ppt declined to 0 ppt for at least 2 weeks. For the most part, the floods caused no change in densities of decapod crustaceans and fishes in marsh or bare habitats. Where significant changes did occur, the effect was usually negative for decapod crustaceans and positive for fishes. The mere presence of estuarine crustaceans and fishes after Flood 3, when salinities decreased to near zero, suggested a high degree of physiological tolerance to freshwater flooding. These results suggest that short term lowering of salinity does not deter estuarine animals from using deltaic marshes, but rather it may be longer term habitat changes that cause such responses"--Abstract.
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