Temporal development of salt marsh value for nekton and epifauna: Utilization of dredged material marshes in Galveston Bay, Texas, USA

Densities of nekton and other fauna were measured in three created salt marshes to examine habitat development rate. All three marshes were located on Pelican Spit in Galveston Bay, Texas, USA and were created on dredged material from the Gulf Intracoastal Waterway. The youngest marsh was planted on 1-m centers in July of 1992. At the time sampling was initiated in fall 1992, the marshes were 9, 5, and less than 1 year in age; sampling continued in the fall and spring through spring 1994. Animal densities were measured within the vegetation at two elevations using an enclosure sampler. In the fall of 1992, 4 months following the planting of the 92Marsh, densities of most marsh organisms were lower in this marsh compared with the older two marshes. Significantly lower densities were observed for dominant crustaceans (including three species of grass shrimps, two species of commercially-important penaeid shrimps, thinstripe hermit crabs Clibanarius vittatus, and juvenile blue crabs Callinectes sapidus), a dominant fish (Gobionellus boleosoma), and the dominant mollusc (Littoraria irrorata). By the fall of 1993, however, densities of most nekton species were similar among the three created salt marshes. In contrast, reduced densities of less mobile epifauna (C. vittatus and L. irrorata) persisted in the 92Marsh throughout the 2 years of sampling. The patterns of nekton utilization exhibited in these marshes suggest that the 92Marsh reached its maximum habitat support function for these animals in less than 1 year. Comparisons of the older marshes with natural marshes in the bay system, however, suggest that all three of these created marshes are functioning at lower levels than natural marshes in terms of supporting production of commercially important fishery species such as penaeid shrimps and C. sapidus