...Bay, Little Egg Harbor, Little Bay, Reeds Bay, Absecon Bay, and contiguous nearshore ocean waters (including the Long-term Ecosystem Observatory at 15 m). Acquisition of these data is necessary to effectively address coastal resource management problems in this region of the state. Located in southern New Jersey at ~39[degrees]N, 74[degrees]W the JCNERR system encompasses more than 27,000 ha of open water habitat. Between 1976 and 1996, Rutgers University monitored temperature, salinity, and turbidity at single site (i.e., Rutgers University Marine Field Station) in the JCNERR. Since 1996, the most comprehensive database on water quality in the reserve has been collected as part of the System-wide Monitoring Program (SWM P) established by the National Estuarine Research Reserve System. The JCNERR currently monitors six water quality variables (i.e., water temperature, salinity, dissolved oxygen, turbidity, pH, and depth) semi-continuously at five sites. Three SWMP monitoring sites are located along a salinity gradient in the Mullica River Great Bay Estuary. A long-term SWMP data set compiled at the JCNERR enables the accurate determination of both intra-annual (seasonal) and inter-annual patterns of physical-chemical variables, which are analyzed here for the 1996-2000 monitoring period. Results of this analysis indicate that the Mullica River-Great Bay Estuary is a well-oxygenated system with no evidence of hypoxic conditions. In addition, the estuary remains remarkably pristine and characterized by minimal anthropogenic impacts. Thus, it serves as an excellent reference site for comparison with other estuaries. This type of study is important not only because it can be used to delineate the factors responsible for biotic co mmunity changes in the estuary but also because it can provide essential data to decision-makers who address coastal resource management problems.

KEY WORDS: Mullica River-Great Bay Estuary, physical-chemical variables, water quality, system-wide monitoring

INTRODUCTION

The Jacques Cousteau National Estuarine Research Reserve (JCNERR) is the 25th program site of the National Estuarine Research Reserve System (NERRS) (Figure 1). The principal mission of the JCNERR program is to conduct long-term scientific research and monitoring to characterize the natural and anthropogenic processes governing stability and change in the Mullica River, Great Bay, Lower Barnegat Bay, Little Egg Harbor, Little Bay, Reeds Bay, Absecon Bay, and contiguous nearshore ocean waters, and to provide the data necessary to effectively address coastal resource management problems. The reserve program also focuses on improving the protection of estuarine resources for designated uses such as public health, recreation, and support of the estuarine ecosystem. In addition, it enhances public awareness and understanding of the estuarine and watershed areas in the region through public education, interpretation, and outreach.

The Institute of Marine and Coastal Sciences at Rutgers University is the lead institution overseeing operations of the JCNERR program. Rutgers University has been collecting water quality data and conducting basic and applied research within the Mullica River-Great Bay estuarine system since the 1950s (Durand and Nadeau, 1972; Durand, 1988). With the acquisition of its marine field station on Great Bay in 1972, the University began collecting extensive environmental data on Great Bay and contiguous waters. Other collaborative agencies and partners in the program include the Richard Stockton College of New Jersey, New Jersey Department of Environmental Protection, U.S. Fish and Wildlife Service, U.S. Geological Survey, Pinelands Commission, and Tuckerton Seaport.

The JCNERR is unique for several reasons. The Mullica River-Great Bay Estuary exhibits exceptional environmental quality, and is generally considered one of the most pristine and least (anthropogenically) impacted estuarine systems in the densely populated urban corridor of the northeastern United States (Durand, 1988; Able et al., 1992, 1999). As such, it serves as an ideal reference site for comparison with other estuaries. This is largely attributed to the extensive undeveloped lands of the Pinelands National Reserve (PNR), state wildlife management areas, and federal refuges surrounding these waters (Figure 1). The PNR, totaling nearly 450,000 ha, encompasses much of the forested land in surrounding watershed areas, and it restricts future development in the system (Psuty et al., 1993; Zampella et al., 2001). The terrestrial, wetland, and aquatic habitats of the JCNERR are entirely in public ownership, and the state and federal managed lands provide a significant level of resource protection.

The boundaries for the JCNERR are designed to constitute a natural ecological unit. They enclose a core area of contiguous wetlands, riparian habitats, open waters in Great Bay, and nearshore ocean areas off Little Egg Inlet. The buffer zone includes upland-forested areas adjacent to the core wetland habitats. The Mullica River-Great Bay Estuary forms a highly productive system, which supports a rich diversity and high population abundance of finfish, shellfish, and wildlife.

A major component of the reserve program is the monitoring of estuarine water quality. Water quality data are important because they help to characterize the overall environmental quality of the estuarine system. The purpose of this article is to analyze water quality conditions at three designated system-wide monitoring sites in the reserve (i.e., Lower Bank, Chestnut Neck, and Buoy 126). A primary reason for selecting these station locations is the well-defined salinity gradient occurring along the Mullica River-Great Bay Estuary.

PHYSICAL-CHEMICAL CHARACTERISTICS

The JCNERR is located in southern New Jersey (~39[degrees]N, 74[degrees]W) approximately 15 km north of Atlantic City. It consists of a wide array of aquatic, terrestrial, and wetland habitats, which cover an area of more than 45,000 ha (Figure 1). The areal extent includes a part of the Mullica River-Great Bay drainage basin as well as Lower Barnegat Bay, Little Egg Harbor, Great Bay, and the back bays (i.e., Little Bay, Reeds Bay, and Absecon Bay) as far south as Absecon. The downstream boundary extends about 9 km onto the adjacent inner continental shelf to the Long-term Ecosystem Observatory (LEO-15), a 2.8 [km.sup.2] offshore research site of Rutgers University. LEO-15 is located at a shallow (~15 m deep) sand ridge (Beach Haven Ridge) that measures about 4.5 km long and 1 km wide on the inner continental shelf off Little Egg Inlet (Figure 2).

Open water is the predominant habitat in the reserve, encompassing 27,599 ha (~60% of the area). Marsh blankets an additional 13,034 ha (>28% of the area) and forest cover, 4,616 ha (~10% of the area). Developed landscape provides the least cover (slightly over 1% of the area), accounting for 553 ha. Domestic development near the reserve is relatively sparse; it is concentrated in two small communities, Mystic Island and Tuckerton, whose boundaries extend to within 3 km of the Great Bay shoreline (Psuty et al., 1993). Thus, natural habitats dominate the reserve, being comprised of lowland and upland forests, wetlands, open estuarine and nearshore ocean waters, and barrier islands.

The Great Bay-Little Egg Harbor estuarine complex, which lies in the central portion of the Mid-Atlantic Bight, comprises shallow, polyhaline embayments bordered by extensive salt marshes and more than 280 km of shoreline. Covering an area of 41.6 [km.sup.2], Great Bay forms a roughly circular embayment with a diameter of about 7 km. Little Egg Harbor is a larger, irregularly-shaped, bar-built estuary, covering approximately 125 [km.sup.2]. Both are shallow water bodies with an average depth of 1.1 m near the mouth of Great Bay) (Szedlmayer and Able, 1996). Salinity in the embayments generally ranges from ~10[right arrow]32%.

Subtidal motion in the coastal bays of the JCNERR is principally driven by coastal pumping remotely forced by coastal sea level (Chant, 2001). In the Intracoastal Waterway channel inside of Little Egg Inlet, strong tidal movement is distorted by overtides and residual motion (Chant et al., 2000). Flood currents moving northward into Little Egg Harbor diverge into northwestward- and northeastward-flowing components, producing complex circulation patterns in the central basin. During ebb tide, the currents are reversed, and they flow southward. Tidal currents typically range from ~0.5-1.0 m/s in the lower estuary, decreasing in magnitude upestuary (Chant, 1997).

Tidal currents enter Great Bay through Little Egg Inlet at a velocity of greater than 2 m/s. They flow eastward along the northern part of the bay and merge with freshwater discharging from the Mullica River that flows along the southern margin of the bay westward toward Little Egg Inlet. This current flow pattern creates a counterclockwise gyre in the central basin (Durand, 1988).

The JCNERR is characterized by temperate climatic conditions typical of the Mid-Atlantic region. The seasons are well defined; however, seasonal air temperatures vary considerably from year to year as in other temperate systems. The coldest temperatures occur during January, and the warmest temperatures, during July. The average winter temperature range is 0-2.2[degrees]C, compared to an average summer temperature range of 22-24[degrees]C. The Atlantic Ocean moderates seasonal temperatures in the lower drainage basin and bays. Farther inland away from the influence of the ocean, air temperature extremes can be great. For example, winter air temperatures less than -20[degrees]C have been recorded in the Pine Barrens region, with summer air temperatures occasionally exceeding 38[degrees]C (Forman, 1998).

Winds predominate from the northwest and southwest. The prevailing winds during the December through March period are from the northwest. Southerly onshore winds predominate in the late spring and summer. Wind velocities are generally less than 15 km/ hr. Warm tropical air masses from the south and southwest deliver hot, humid weather conditions during summer. Afternoon sea breezes reduce summer temperatures within 10-15 km of the coastline (Kennish, 2001).

Precipitation, mainly in the form of rain, averages between 100 and 122 cm/yr (Able et al., 1999). It is relatively evenly distributed year-round. Heavy precipitation accompanies northeasters in the winter; thunderstorms caused by localized convection frequently develop during the summer and early fall. The northeasters typically form in waters off the southeast coast of the United States and move north and northeast producing strong winds, heavy surf, and occasional tidal flooding. The thunderstorms are usually of high intensity and short duration. Extratropical storms and hurricanes arise during late summer and early fall, although they often pass east of the reserve. These storms can also generate destructive winds and considerable precipitation (e.g., 10 cm or more) that have the potential to cause serious flooding problems, soil erosion, and structural damage (Kennish, 2001).

The Gulf Stream plays a vital role in the development of northeasters. This northward flowing, warm-water current parallels the eastern seaboard, heating the overlying air and creating a front along the coast. Subsequently, surface low pressure systems can form as jet stream disturbances move over...

NOTE: All illustrations and photos have been removed from this article.



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