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Environmental concentrations and biological effects of certain metals and organic compounds found in wood preservatives were examined. The study focused on leachates from private residential docks in South Carolina tidal creeks. Copper, chromium, arsenic, and polynuclear aromatic hydrocarbons (PAHs) were measured in composite samples of surficial sediments and naturally occurring oyster populations (Crassostrea virginica) from creeks with high densities of docks, and from nearby reference creeks with no docks. In some cases, metal concentrations in sediments and oysters were higher immediately adjacent to dock pilings than they were elsewhere in the same creek. Sediments from most sites had concentrations of metals and total PAHs which were below levels reported to cause biological effects, however. Solid-phase Microtox(R) bioassays using whole sediments and rotifer bioassays using sediment pore water showed no significant differences in acute toxicity between creeks with and without docks. Oysters growing directly on dock pilings had significantly higher concentrations of copper than oysters growing at least 10 m away; however, there was no significant difference in the physiological condition of these oysters. Four-day field bioassays measuring percent survival of mummichogs (Fundulus heteroclitus), mud snails (Ilyanassa obsoleta), juvenile red drum (Sciaenops ocellatus), and juvenile white shrimp (Penaeus setiferus) showed no significant differences between sites near to and distant from newly constructed docks. Hatchery-reared oysters showed no significant differences between dock and reference sites in percent survival, growth, or bioaccumulation of metals after six weeks of exposure. The results suggest that, in estuarine environments with a moderate tidal range (1.5-2.0 m), wood preservative leachates from dock pilings have no acutely toxic effects on four common estuarine species, nor do they affect the short-term survival or growth of juvenile oysters.

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We examined the recovery of vegetation and salt marsh macrofauna in a pipeline construction corridor at two locations where it intersected intertidal salt marshes near Charleston, SC. The impacts of construction were evaluated prior to construction and for subsequent periods of 34 and 46 months at the two sites using aerial photography and three field sampling methods. Quadrats were used to estimate densities of selected salt marsh invertebrates, as well as stem densities and aboveground wet-weight biomass of Spartina alterniflora; pit traps were employed to simulate natural tidal pools for sampling small, motile epibenthic macrofauna that remained on the marsh surface at low tide; and flume nets were used to sample the natant macrofauna that used the marsh edge at high tide. The analyses of vegetation by quadrat and aerial imagery clearly showed that the recovery of Spartina was more rapid and complete at the Ashley River site (88%) than at Wappoo Creek (48%). In contrast to this apparent, if partial, vegetative recovery, several salt marsh invertebrates, including Littorina irrorata and Geukensia demissa, were eliminated from the corridor during construction and showed scant recovery by the end of our study, Differences in species composition and abundance of natant organisms in the flume net collections also supported the conclusion that faunal recovery was incomplete after 3-4 years at these sites. The recovery of functional equivalency of the excavations, compared with natural marshes, was not evaluated during our study, but we speculate that their functioning may equilibrate over time, since preexisting hydrologic conditions are more or less intact, seedstock for Spartina revegetation is nearby, and macrofauna will probably eventually reestablish themselves from adjacent areas.

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