The Effects of Smothering a 'Spartina alterniflora' Salt Marsh with Dredged Material.

摘要

A study of the capability of high salt marsh to recover from disposal of dredged material indicates that smothering high marsh could be a feasible disposal alternative but should be used with caution and should only be employed when other alternatives are economically or physically infeasible. The study investigated the impact of smothering short form Spartina alterniflora in Glynn County, Ga., with three types of dredged material (coarse sand, sand and clay mixed, and clay), at six depths (8, 15, 23, 30, 61, and 91 cm), and at different stages of plant growth (february, July, and November) over two growing seasons. Spartina alterniflora was able to penetrate up to 23 cm of each type of dredged material and exhibited biological growth and production nearly equal to that in undisturbed marsh. These depths, being within the elevational range of the marsh, indicate that accurate tidal and elevational data should be collected before disposal on a marsh and that deposition should not exceed the elevational limit of the existing marsh. The study also assessed the impact of smothering on selected species of crabs and snails. Crabs were able to recolonize areas covered with up to 23 cm of clay dredged material and 15 cm of sand. Snails rapidly recolonized material placed 8 and 15 cm deep. Faunal recovery may depend on the proximity of the disposal area to natural populations and the extent of the smothered areas.