Benthic and Epibenthic Fauna


    The species composition, dominance, abundance, and diversity of benthic and epibenthic organisms are monitored as an indicator of potential biotic consequences of changes in tidal amplitude, tidal excursion, or salinity resulting from the channel deepening project. Changes in wetland inundation regimes and the location of salinity isoclines may have dramatic effects on recruitment success and survival of benthic infauna and habitat availability to wetland associated fish and decapods. Channel alterations may lead to changes in relative composition and distribution of benthic and epibenthic organisms.





Preliminary Results

    The benthic infaunal community is currently dominated by polychaetes (~40%, Maranzellaria, Polydora, Streblospio ) and oligochaetes (~50%) in the saline areas and by oligochaetes (~40%, Tubificoides), insect larvae (~25%), and polychaetes (~25% , Hobsonia) in the fresh areas. The epibenthic community consists of wetland associated fish and decapods, such as Palaeomonetes, Lagodon, Fundulus, Leiostomus, Gobionellus in the saline areas and Paralichthys, Uca, Leiostomus, Anguilla in the fresh areas.


    Vegetation assemblages at each station were characterized in August 2000. Dominant vascular plant species were surveyed and noted along each transect in each of three strata: canopy, shrub and herb. In the portion of each transect closest to the stream, a stand of sensitive herbaceous species has been identified and its location has been recorded using GPS. Sensitive vegetation is defined as any perennial herb that is characteristic of fresh or brackish marsh/ swamp habitats. Sensitive vegetation was not found at all stations. See table 1 for a list of dominant herbaceous species found at each station in August 2000. These stands will be re-evaluated each year for changes in dominant sensitive herbaceous species.


Table 1. List of dominant sensitive herbaceous species