I. INTRODUCTION

On January 1 and 2, 1990, an oil spill of 576,000 gal of No. 2 heating oil from an underwater Exxon pipeline seriously affected wildlife and aquatic plant communities of the Arthur Kill, the strait separating Staten Island, New York, from New Jersey (Burger 1994; Figure 1 and Figure 2). The leak occurred at Morses Creek in the northern reach of the Kill, and affected areas as far north as the Kill van Kull and Newark Bay, and as far south as the Outerbridge Crossing. The total petroleum hydrocarbon (TPH) content of sediments in the area was as high as 120,000 µg/g, and exceeded 1000 µg/g in about 50% of the sediments tested (Louis Berger and Associates 1991). In areas closest to the spill, the dominant vegetation of the low marsh -- saltmarsh cordgrass (Spartina alterniflora) -- was eradicated, and mussel beds were heavily damaged, locally experiencing up to 100% mortality (Louis Berger and Associates 1991). Approximately 700 aquatic birds were killed outright, and the 1990 breeding season was seriously disrupted.

The New York City Department of Parks and Recreation's Salt Marsh Restoration Team (SMRT) implemented a multiyear restoration and monitoring project to restore those parts of the marshes directly impacted by the 1990 oil spill. Restoration activities included the successful reintroduction of over 9 acres of Arthur Kill-propagated S. alterniflora (Bergen et al. 2000). The SMRT has been monitoring several parameters both in oiled marshes that were replanted and in oiled marshes that were left for natural recovery. Those parameters included: peak standing biomass, stem and flower density, and height of saltmarsh cordgrass; sediment TPH; density of ribbed-mussels (Geukensia demissa); fish abundance and diversity; and wading bird (egret) foraging success (Bergen et al. 2000; C. Alderson et al., Salt Marsh Restoration Team, Natural Resources Group, New York City Parks, 200 Nevada Ave., Staten Island, NY, pers. comm. and unpubl. data).

Understanding the development and functional value of restored salt marshes requires an understanding of how natural salt marshes function. There have been several studies comparing the relative and functional value of restored marshes to natural marshes (e.g., Cammen 1976; Race and Christie 1982; Pacific Estuarine Research Laboratory 1990; LaSalle et al. 1991; Minello and Zimmerman 1992; Zedler 1993; Matthews and Minello 1994; Sacco et al. 1994; Havens et al. 1995; Thompson et al. 1995; Levin et al. 1996; Simenstad and Thom 1996; see also Kentula 2000). However, many restored wetlands have not been scientifically evaluated for their success in approaching the equivalent functional levels of natural wetland habitats; indeed, determining the "functional equivalency" of a restored wetland compared to a natural wetland is very difficult, and appraising the success of a restoration is problematic (e.g., see Simenstad and Thom 1996; Kentula 2000; Zedler and Callaway 2000). Lewis (2000) noted that "no generally accepted and applied criteria for establishing goals for coastal wetland restoration projects exist even today," although authors such as Short et al. (2000) are in the process of developing success criteria for estuarine restoration projects. In fact, the term "restored" itself is not quite correct: most current research in this field focuses on created or constructed salt marshes [marshes created in response to mitigation efforts; e.g., Zedler et al. (1997)], rather than those that have been restored or rehabilitated as a result of a severe environmental impact. Thus, although the replanting of S. alterniflora in the Arthur Kill was considered both successful and exceptional, and some SMRT monitoring results showed increased aquatic faunal and avian abundances at replanted sites (C. Alderson et al., Salt Marsh Restoration Team, Natural Resources Group, New York City Parks, 200 Nevada Ave., Staten Island, NY, pers. comm. and unpubl. data), questions remain as to the ecological viability and functional equivalency of these marshes.

The problem is compounded because not only was almost every low marsh within the Arthur Kill affected to some extent by the 1990 spill, but this estuary is also heavily urbanized, and the marshes are continuously impacted by urban runoff, contaminants, floatables, bank erosion, and illegal dumping which together can severely restrict natural recolonization of S. alterniflora. Thus, it may be difficult to detect differences in the ecosystem functions between the replanted marshes and the pre-existing marshes within the Arthur Kill. Even if differences are detected, it may be impossible to attribute these differences to the replanting efforts or to the oil from the spill after so many years. These difficulties are often encountered when undertaking environmental impact or restoration studies, particularly in urban wetland habitats (Ehrenfeld 2000). Thus, as a first step, Ehrenfeld (2000) states: "Measures of restoration success and functional performance [in urban wetlands] must start with an appreciation and assessment of the particular conditions imposed by the urban environment. These conditions can be identified, measured, and incorporated into assessment protocols for individual wetland functions."

Therefore, the primary goal of this study is to supplement the SMRT monitoring efforts via a preliminary characterization and assessment of marshes that were oiled and replanted, marshes that were oiled but not planted, and nearby pre-existing S. alterniflora reference marshes, with a view toward noting any differences among sites, especially those that might be attributable to the replanting efforts. Measured parameters include trace metals and hydrocarbon contaminants in ribbed-mussels and sediments, sediment biogeochemistry, age and growth of ribbed-mussels, macrobenthic distribution and abundance, and diets of the common mummichog (Fundulus heteroclitus). Monitoring by itself often centers only on the structural attributes of the wetland; explicit measures of function, such as biogeochemistry and the trophic linkages between the fish and benthic communities (e.g., Moy and Levin 1991) can provide a more integrated assessment of ecosystem processes, as well as measure the progress of restoration (Simenstad and Thom 1996). Thus, this preliminary characterization, although limited, both complements and goes beyond the current monitoring studies of New York's SMRT, and may allow us to better evaluate our ability to restore the functional attributes of this habitat, as well as to identify potential indicators of habitat and living marine resource health, impacts, and recovery within a heavily urbanized and degraded estuary.

SITE DESCRIPTIONS

Six Arthur Kill marshes were selected: two oiled and replanted, two oiled but unplanted, and two pre-existing S. alterniflora reference marsh sites (Figure 1 and Figure 2). For the trace metals and hydrocarbon analysis studies, mussels were collected farther south and east in the relatively pristine Sandy Hook Bay (Figure 1) to use as an additional reference.

Sampling occurred in September 1996 and May 1997. Mummichogs were scarce in spring 1997, so that year, sampling for those fish occurred from May until early August.

Replanted and Unplanted Sites

Old Place Creek and marsh surrounds the Goethal's Bridge in the northern end of the Arthur Kill between Elizabethport Reach and Gulfport Reach. The site is almost directly across from the origin of the spill and was heavily oiled, with replanting occurring around 1993. Oily residues were still found at this site in 1996-97. The shoreline was heavily impacted by tugboat and wind-generated waves. The combination of wave energy and Old Place Creek's close proximity to the Bayway Refinery have left parts of the shoreline devoid of both vegetation and the thick layers of peat generated since the last glaciation. Some parts of the marsh (outside of our study area) were fouled by an asphalt spill in the 1980s, and the substrate was later stripped. For a further description of this marsh, the impact of the oil spill, and subsequent replanting, see Bergen et al. (2000), as well as Blanchard et al. (2001).

The Consolidated Edison Tower (i.e., "Con Ed Tower") site is located at the junction of the northern end of Prall's Creek and the Arthur Kill. The area was not replanted (although it may be in the near future) and was barren; the substrate consisted of a combination of asphalt-covered peat, exposed peat, and sand-and-gravel-covered peat or asphalt. The substrate still had oily residues at the time of our sampling.

The Saw Mill Creek North marsh site is located on the northern shoreline of Saw Mill Creek. The replanted site occupied a narrow 3-6 m wide band which ran 91 m in length from the mouth of the creek east into the full marsh. Damage and destruction by oil at this site consisted of the loss of S. alterniflora and subsequent erosion of peat and adjacent high marsh. Replanting occurred in 1992.

The unplanted Saw Mill Creek South site is on the opposite (south) shore of the creek. The width of the denuded area was not as wide as that on the north shore. Since the oil spill, erosion of the denuded south banks has occurred, but S. alterniflora has re-established itself without the need for replanting. Unlike the barren Con Ed Tower site, the unplanted Saw Mill Creek South site was visually indistinguishable from the replanted Saw Mill Creek North site by 1996.

Reference Sites

Many authors have noted the importance of choosing reference sites that adequately reflect the conditions of the restoration site, and that encompass the known variation of the group of wetlands in the study (e.g., Brinson and Rheinhardt 1996; Kentula 2000; Short et al. 2000). Reference sites in urban areas will, and should, reflect the realities of the urban context [see Ehrenfeld (2000) and authors cited therein for an extended discussion of reference sites in urban wetland restoration studies]. Thus, at least one of the two pre-existing S. alterniflora reference marshes we chose was affected to some degree by the oil spill, and both are continually affected by anthropogenic impacts, as are all marshes within the Arthur Kill itself. In fact, it would not have been possible or even feasible to find or use a "pristine" marsh within the Arthur Kill.

The first site, Tufts Point, is located midway on the New Jersey side, and extends out into the Kill where it turns sharply to the west between Fresh Kills Reach and Port Reading Reach. After the oil spill, the site suffered some "medium oiling" according to Louis Berger and Associates (1991). There was a high mortality of the ribbed-mussel, a common bivalve mollusk residing in the low marsh and predominantly attached to the stems and roots of S. alterniflora. Nevertheless, relative to the more northern marshes, the site did not suffer extensive damage after the 1990 spill, and was considered by SMRT to be in good condition. Therefore, we considered it as a reference marsh.

The second reference site, Mill Creek marsh, is located in the Outerbridge Reach, just to the south of the Outerbridge Crossing on Staten Island. It was our southernmost site. The study marsh itself was located on an island right at the mouth of the creek; at very low tides the water over the surrounding mudflats was shallow enough to allow easy access to the mainland. Although Mill Creek marsh was located in the "lightly-impacted" zone (Louis Berger and Associates 1991) of the 1990 spill, Louis Berger and Associates (1991) nevertheless observed no oiling there, and declared it a control site.

The Sandy Hook reference site used for contaminant analyses was located on the western shoreline of the barrier beach peninsula, in Sandy Hook Bay (Figure 1), where there are a series of marshes and mud flats that are exposed during periods of low tide in an area south of Spermaceti Cove and north of Plum Island. The site was considered to be relatively clean, especially compared to the Arthur Kill.

REFERENCES CITED

Bergen, A.; Alderson, C.; Bergfors, R.; Aquila, C.; Matsil, M.A. 2000. Restoration of a Spartina alterniflora salt marsh following a fuel oil spill, New York City, NY. Wetlands Ecol. Manage. 8:185-195.

Blanchard, P.P., III; Kerlinger, P.; Stein. M.J. 2001. An islanded nature -- natural area conservation in western Staten Island, including the Harbor Herons Region. Washington, DC: The Trust for Public Land, and, New York City Audubon Society; 224 p.

Brinson, M.M.; Rheinhardt, R. 1996. The role of reference wetlands in functional assessment and mitigation. Ecol. Appl. 6:69-77.

Burger, J., editor. 1994. Before and after an oil spill: the Arthur Kill. New Brunswick, NJ: Rutgers Univ. Press; 305 p.

Cammen, L.M. 1976. Abundance and production of macroinvertebrates from natural and artificially established salt marshes in North Carolina. Am. Midl. Nat. 96:487-493.

Ehrenfeld, J.G. 2000. Evaluating wetlands within an urban context. Ecol. Eng. 15:253-265.

Havens, K.J.; Varnell, L.M.; Bradshaw, J.G. 1995. An assessment of ecological conditions in a constructed tidal marsh and two natural reference tidal marshes in coastal Virginia. Ecol. Eng. 4:117-141.

Kentula, M.E. 2000. Perspectives on setting success criteria for wetland restoration. Ecol. Eng. 15:199-209.

LaSalle, M.W.; Landin, M.C.; Sims, J.G. 1991. Evaluation of the flora and fauna of a Spartina alterniflora marsh established on dredged material in Winyah Bay, South Carolina. Wetlands 11:191-208.

Levin, L.; Tally, D.; Thayer, G. 1996. Succession of macrobenthos in a created salt marsh. Mar. Ecol. Prog. Ser. 141:67-82.

Lewis, R.R., III. 2000. Ecologically based goal setting in mangrove forest and tidal marsh restoration. Ecol. Eng. 15:191-198.

Louis Berger and Associates, Inc. 1991. Arthur Kill oil discharge study. Vol 1. Final report, and, Vol. 2. Appendices. Submitted to: New Jersey Department of Environmental Protection and Energy, Trenton, NJ.

Matthews, G.A.; Minello, T.J. 1994. Technology and success in restoration, creation, and enhancement of Spartina alterniflora marshes in the United States. Vol. 1 -- Executive summary and annotated bibliography. NOAA Coast. Ocean Prog. Decision Anal. Ser. 2.

Minello, T.J.; Zimmerman, R.J. 1992. Utilization of natural and transplanted Texas salt marshes by fish and decapod crustaceans. Mar. Ecol. Prog. Ser. 90:273-285.

Moy, L.D.; Levin, L.A. 1991. Are Spartina marshes a replaceable resource? A functional approach to evaluation of marsh creation efforts. Estuaries 14:1-16.

Pacific Estuarine Research Laboratory. 1990. A manual for assessing restored and natural coastal wetlands with examples from southern California. Calif. Sea Grant Rep. T-CSGCP-021.

Race, M.S.; Christie, D.R. 1982. Coastal zone development: mitigation, marsh creation, and decision-making. Environ. Manag. 6:317-328.

Simenstad, C.A.; Thom, R.M. 1996. Functional equivalency trajectories of the restored Gog-Le-Hi-Te estuarine wetland. Ecol. Appl. 6:38-56.

Sacco, J.N.; Seneca, E.D.; Wentworth, T.R. 1994. Infaunal community development of artificially established salt marshes in North Carolina. Estuaries 17:489-500.

Short, F.T.; Burdick, D.M.; Short, C.A.; Davis, R.C.; Morgan, P.A. 2000. Developing success criteria for restored eelgrass, salt marsh and mud flat habitats. Ecol. Eng. 15:239-252.

Thompson, S.P.; Paerl, H.W.; Go, M.C. 1995. Seasonal patterns of nitrification and denitrification in a natural and a restored salt marsh. Estuaries 18:399-408.

Zedler, J.B. 1993. Canopy architecture of natural and planted cordgrass marshes: selecting habitat evaluation criteria. Ecol. Appl. 3:123-138.

Zedler, J.B.; Callaway, J.C. 2000. Evaluating the progress of engineered tidal wetlands. Ecol. Eng. 15:211-225.

Zedler, J.B.; Williams, G.D.; Desmond, J.S. 1997. Wetland mitigation: can fishes distinguish between natural and constructed wetlands? Fisheries 22:26-28.

To Chapter 2