Introduction

The reshaping of New York Harbor by European settlers first occurred in the mid 1600s with the construction of two small, wooden piers along the East River to accommodate shipping and trade (Buttenwieser, 1987). From this modest start, the East River became an active seaport by the 1700s and efforts then were already underway to reshape its shoreline and construct larger piers in its waters. In contrast, waterfront development in the lower Hudson River lagged behind because the hard, rocky bottom of the Battery Park area tended to make pier building difficult (Buttenwieser, 1987). Eventually, the development of powerful pile-driving machinery overcame this obstacle and by the late 1800s the Hudson River supported hundreds of piers and docks.

Many eighteenth and nineteenth century piers were built upon filled, closed bases and were often situated in parallel and in close proximity to one another. These designs made piers more stable and capable of servicing larger ships, but they also obstructed water flow (Bone, 1997). Other early piers were made of wood and floated on the surface of the water in closed squares or rectangles, also restricting flow and allowing the buildup of stagnant water and refuse. In 1870, health concerns prompted open hearings held by the Department of Docks (1870-1942) where the construction of open-piling finger piers was suggested (Buttenwieser, 1987). This form, piers built on open piling bases and at right angles to the shoreline, is now common in New York Harbor.

The goalof the Department of Docks was to modernize the harbor for commercial shipping and they oversaw the construction of stone, iron, and concrete finger piers on amassive scale. Environmental impacts were largely ignored in favor of expanding trade capacity (Bone, 1997). During this era, Chelsea Piers were created as were numerous ferry terminals, warehouses, and immense stone and iron piers. In addition, the Department radically transformed the geography of Manhattan's waterfront, straightening the natural contours, dredging, and constructing an extensive system of riverwalls and bulkheads (Betts, 1997). Yet in spite of these efforts, the decline of New York Harbor as a commercial port was evident by the 1920s. Noncommercial interests along the Upper West Side had already defeated measures to commercialize the principally residential neighborhoods and pushed instead to develop open, recreational spaces. The creation of Riverside Park and the later construction of recreational piers and athletic facilities effectively halted maritime commercial activity on the West Side. The continued decline of major shipping in New York Harbor came in the 1960s when commerce relocated to New Jersey's Elizabeth Seaport (Butten-wieser, 1987).

Today much of the New York Harbor waterfront stands in disuse and disrepair. There is a strong interest in revitalizing the city's waterfront including construction of the Hudson River Park (www.hudsonriverpark.org). When completed, this park will be a five-mile-long public walkway along the HudsonRiver stretchingfrom Battery Place to 59th Street, and its development includes the restoration of thirteen preexisting piers (Wise, Woods, and Bone, 1997). Other plans for the waterfront include Trump Place on the Hudson River front between 59th and 72nd streets. Though the city is in need of more open space, there are apprehensions about the impacts of pier restoration and construction activity on the surprisingly resilient biological resources of the Hudson River Estuary (Able and Duffy-Anderson, 2005).

The concern for the Hudson River Estuary ecosystem is not misplaced. The progressive transformation of the Hudson River has taken its toll on near-shore habitats. Over the years, the practices of dredging, filling, and bulkheading have eliminated the naturally sloping land-sea interfaces of tidal marshes and beaches (Squires, 1992). Nearly 50,000 acres of tidal wetlands have been lost inNew York Harbor, and over 20 percent of that loss has occurred recently, between 1950 and 1970 (Bone, 1997). Landfill and piers have been pushed out farther and farther into the Hudson River channel and have gradually created a passageway that is considerably more narrow than its pre-European state. These changes have likely affected local circulation patterns, water velocity, and bottom topography.

In spite of these perturbations, the Hudson River and its estuary are functional ecosystems that support a complex mosaic of animal life in their waters. Biological productivity is high and a variety of species of zooplankton (Stepien, Malone, and Chervin, 1981; Pace, Findlay, and Lints, 1992), deposit feeders (Rice et al., 1995), and suspension feeders (Strayer et al., 1994) are supported. An array of larger invertebrate organisms such as sevenspine bay shrimp (Crangon septemspinosa), daggerblade grass shrimp (Palaemonetes pugio), blue crabs (Callinectes sapidus), and a variety of molluscs are also common (Stanne, Panetta, and Forist, 1996), and many of these serve as prey for economically valuable species including Atlantic sturgeon (Acipenser oxyrinchus) (Dovel and Berggren, 1983; Van Eenennaam et al., 1996), shortnose sturgeon (Acipenserbrevirostrum) (Hoff, Klauda, and Young, 1988), American shad (Alosa sapidissima) (Smith, 1985), striped bass (Morone saxatilis) (Waldman et al., 1990), and blue crabs (Wilson and Able, 1992). The estuary also provides critical spawning and juvenile habitat for a variety of ecologically important fish species such as Atlantic tomcod (Microgadus tomcod) (Dew and Hecht, 1994a; 1994b), winter flounder (Pseudo-pleuronectes americanus) (Able, Manderson, and Studholme, 1998), bluefish (Pomatomus saltatrix) (Chiarella and Conover, 1990), alewife (Alosa pseu-doharengus) (Dovel, 1981), and bay anchovy (Anchoa mitchilli) (Dovel, 1981), among a variety of others (Able and Fahay, 1998). Finally, the Hudson River Estuary is an important migratory pathway for striped bass (Secor and Piccoli, 1996) and shad (Limburg, 1996), and provides important overwintering grounds for striped bass as well (Hurst and Conover, 1998).

The Hudson River Estuary is resilient but its aquatic species assemblage continues to be vulnerable to anthropogenic stress. Factors that degrade water quality such as chemical pollution, industrial discharge, municipal runoff, and sewage effluents compete with biological uses of the estuary. Efforts have been made to improve water and sediment quality in the lower Hudson River (Brosnan and O'Shea, 1996; O'Connor, Ranasinghe, and Adams, 1998), but there has been little effort to remedy the effects of centuries of shorezone modifications.

There have only been a few studies that examined the impact of man-made structures on estuarine fauna (Cantelmo and Wahtola, 1992; Stoecker, Collura, and Fallon, 1992) and as a result, we were interested in determining the impacts of man-made structures, especially large piers, on

fr- Pile Field - Open Water

Hudson River fr- Pile Field - Open Water

Figure 29.1. Location of the study areas in the lower Hudson River. Adapted from Able et al. (1998).

fishes in the lower Hudson River. In this chapter, we focus on the lower Hudson River and synthesize the results of our efforts from 1993 to 1999 to assess the effects of large municipal piers on juvenile fishes and selected invertebrates. Results of these studies may be representative of the effects of piers in general and could be of considerable interest to managers, developers, and conservationists working in the Hudson River Estuary and in other urban estuaries.

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