The use of Juncus and Spartina marshes by fisheries species in Lavaca Bay, Texas, with reference to effects of floods.




Zimmerman, R.J.
Minello, T.J.
Smith, D.L.
Kostera, J.

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U.S. National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Galveston Laboratory.


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 parts per thousand. In general, the coast and delta habitats were used similarly. The same species were abundant in both areas. Densities of penaeid shrimps, blue crab, and economically important fishes were usually not significantly different between coast and delta habitats. 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. For the most part, the floods caused no change in densities of decapod crustaceans and fishes in marsh or bare habitats. Results suggest that short term lowering of salinity does not deter estuarine animals from using deltaic marshes.


40 p.


floods, marshes, Spartina sp., Juncus