Intertidal wetland habitats may be utilized extensively by early life stages of estuarine nekton species. These organisms facilitate the transfer of detrital-based energy from productive intertidal habitats to shallow subtidal areas and, ultimately, to deeper coastal waters. Previous research on intertidal nekton communities has identified determinants of communty structure and distribution; however, few studies have compared nekton utilization of disparate intertidal habitats.
In this study, abundance and distribution patterns of marsh-resident nekton were objectively compared between tidal freshwater and salt marshes, using standardized sampling methodology. Despite phyico-chemical differences and variation in general community composition, the resident nekton community of disparate tidal marsh surfaces is similar, characterized by a few ubiquitous species with broad environmental tolerances. Microtopography, hydroperiod, and location along the estuarine salinity gradient were investigated as potential variables influencing patterns of intertidal habitat use by sub-adult nekton. A positive correlation was observed between hydroperiod and nekton abundance at salt marshes; an opposite pattern was observed at tidal freshwater marshes. In addition, between-site differences in species and size-specific utilization patterns were observed. Tidal flooding is an important determinant of the abundance and distribution of intertidal nekton, however, the effect may be confounded by other environmental variables, such as the seasonal presence of submerged aquatic vegetation in adjacent sub-tidal areas.
Intertidal freshwater meiofauna may represent an important trophic link in tidal freshwater wetlands; ostracods, copepods and other meiofauna are frequently consumed by juvenile Cyprinodonts (Fundulus spp.) and other nekton utilizing the surface of tidal freshwater wetlands as a nursery area. Meiofauna were sampled from intertidal microhabitats at a tidal freshwater marsh in order to determine community composition, seasonality and microhabitat distribution. Nematodes, ostracods, tardigrades, oligochaetes (Naididae), copepods (Harpacticoida and Cyclopoida), and the sabellid polychaete Manayunkia numerically dominated monthly collections. Nematodes were abundant in all seasons and represented 37% of total meiofauna. Ostracods and copepods were significantly more abundant in intertidal pools; nematodes, naidids, and Manayunkia spp. were significantly more abundant on vegetative hummock surfaces. These data represent one of few studies on the dynamics of intertidal invertebrate communities in low-salinity estuarine habitats.