Restoration of a Spartina alterniflorasalt marsh following a fuel oil spill, New York City, NY

In the seven years since 2.5 million liters of No. 2fuel oil spilled into the Arthur Kill, the Salt MarshRestoration Team of New York City Parks has restoredSpartina alterniflora(Salt Marsh Cordgrass)to 2.43 ha of shoreline, planting seedlings andtransplants in areas of low salt marsh severelyimpacted by oil. Restoration was undertaken to haltsurface erosion and the loss of surviving vegetationand remnant peat. Biomass, stem density, flowerdensity, height of plants, rhizome spread, basal areaand plant cover were monitored for a minimum of threeyears between 1993 and 1997. Unplanted SeverelyImpacted (USI) reference sites and Existing Vegetation(EV) in the severe impact zone were also monitored.Ninety-five percent of the surface area denuded ofvegetation by oil at USI reference sites remainedunvegetated seven years after the spill. SedimentTotal Petroleum Hydrocarbon (TPH) content was measuredbefore and after plantings and these results indicateda high level of persistent contamination. Residual oilwas not the determining factor in the survival or lossof Spartina alternifloraseedlings andtransplants at planting sites. Instead, plantspacing, shoreline morphology, wave energy generatedby passing vessels, and predation by Brantacanadensis(Canada Goose) were the most criticalfactors. Three years after planting, the abovegroundbiomass at two of the three restoration sites wascomparable to the biomass at existing and restoredeastern North American salt marshes. Seedlings spaced30 cm apart provided rapid cover at two of three sitesand contributed to overall survival. Where initialsurvival was high, goose predation was low. Whereinitial survival was low, shoreline morphology andwave energy were the primary causes of mortality, withgoose predation an important secondary cause. Bedformsat one planting site indicated a high energyshoreline as did sediment texture results for allsites. The fetch along the Arthur Kill is not longenough to generate such high-wave energy, but passingvessels do generate plunging and surging breakers ona regular basis. A reduction in the frequency of oilspills since 1990 has been beneficial to the saltmarshes along the Arthur Kill. A reduction in otheranthropogenic stresses would further enhance theplanted and existing vegetation.