Chesapeake Ecotox Research Program: Research

Regions of Concern

The Chesapeake Bay Program has identified three areas within the Chesapeake Bay ecosystem as Regions of Concern (ROC) due to elevated levels and impacts of chemical contaminants in sediment (Chesapeake Bay Program; 1994). A synoposis follows of what is known about chemical contaminant levels in the Baltimore Harbor, Anacostia River and Elizabeth River.

Baltimore Harbor

The Baltimore Harbor system, including the Patapsco River estuary, is surrounded by the Baltimore metropolitan region. During the past several years, extensive studies have been conducted of the levels of metals, mercury and organic contaminants in Baltimore Harbor sediments (Ashley and Baker, 1999; McGee et al.; 1999; Mason and Lawrence; 1999), surface waters (Bamford et al.; 1999), and the atmosphere (Offenberg and Baker; 1999). Large spatial gradients in contaminant levels in the sediments due to relatively poor mixing result in "hot spots" near storm water outfalls and industrial areas. Elevated levels of polycyclic aromatic hydrocarbons (PAHs) and metals are found around Sparrow's Point, historically the site of intensive coal coking and steel production. Organochlorines, including polychlorinated biphenyls (PCBs), are elevated adjacent to storm water outfalls. Forty percent of the sites within the Baltimore Harbor have PCB levels that exceed the "effects range-medium" value of Long et al. (1995). Survival of the estuarine amphipod Leptocheirus plumulosus was reduced in seven of twenty-five Baltimore Harbor sediment sites studied by McGee et al. (1999). Toxicity at stations in Bear and Colgate Creeks may have been due to sediment-associated metals, while sediment toxicity in the Inner Harbor was likely due to both metals and organic contaminants (polycyclic aromatic hydrocarbons). In addition to the studies above, several current research programs are ongoing to characterize the sources and transport of nutrients and chemical contaminants in the Baltimore Harbor system, including the NSF Long-Term Ecological Research Baltimore Ecosystem Study and the Comprehensive Harbor Assessment and Regional Modeling Study sponsored by the Maryland Department of the Environment. For a recent article on contaminants in Baltimore Harbor, see "Taking on Toxics in Baltimore Harbor" in Maryland Marine Notes.

Anacostia River

Most of the Anacostia's relatively small watershed (440 km²) is within the highly urbanized and suburbanized regions surrounding Washington D.C. The sediments of the Anacostia River are contaminated with a number of pollutants, including organics – polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and pesticides – and trace elements – arsenic (As), cadmium (Cd), copper (Cu), mercury (Hg), lead (Pb), nickel (Ni) and zinc (Zn) (Velinsky et al. 1994; 1997; Wade et al. 1994) that have had substantial biological impacts to benthos (Schlekat et al. 1994). Levels of PCBs, chlordanes and other hydrophobic organic chemicals (HOCs) in wild fish tissues from the Anacostia and the Potomac have also been documented (Velinsky and Cummins 1994, 1996). These two chemicals, and possibly others, pose an ongoing concern for consumers of fish from these rivers in the District of Columbia (DC), Maryland and Virginia and have resulted in fish consumption advisories being posted by the DC government. Current studies of fish tissue concentrations indicate that concentrations of many bio-accumulative organics (e.g., PCBs, chlorates and others) are highest in the bottom-dwelling channel catfish (Ictalurus punctatus) and common carp (Cyprinus carpio) in the Anacostia River (Velinsky and Cummins 1994, 1996). The benthos in this system has also been highly impacted, with observations of substantial decreases in species richness of oligochaete and chironomids, the dominant infaunal benthos in the more impacted areas of the river (Schlekat et al. 1994). For information on Anacostia Restoration, see "Bringing the Anacostia Back" in Maryland Marine Notes.

Elizabeth River

The Elizabeth River watershed is a complex system of branches and small tributaries that also contains a deep water harbor used by the U.S. Navy and many maritime industries. The watershed is approximately 600 km² and ambient water and sediment quality is influenced by the highly industrialized commercial and military activities and densely populated urban areas of the metropolitan Hampton Roads Region. The water and sediment within the river contain at least trace amounts of most pollutants – they come from the use of the harbor system since colonial times, the intensity of industrial and military activities, and the relatively dense urban population. Polycyclic aromatic hydrocarbons (PAHs) occur in sediments in moderate concentrations throughout most of the Elizabeth River and occur in extremely high concentrations in the sediments in the vicinity of sites where creosote was historically used to treat wood for use in the marine environment (Greaves 1990; Alden and Winfield 1995). Trace elements and tributyl tin (TBT), an antifoulant used on ship hulls, are also of concern. The Elizabeth River is closed for harvesting fish and shellfish. Residue concentrations PAHs, PCBs, 4,4'-DDE as well as trace elements – silver (As), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), nickel (Ni) and zinc (Zn) – are present in the muscle and hepatopancreas of the blue crab (Greaves 1990; Alden and Winfield 1993). The macrobenthic communities of the Elizabeth River are considered to be highly impacted with lower species diversity, lower abundance of individuals, lower biomass, and dominance by pollution indicative taxa (Hawthorne and Dauer 1983; Dauer et al. 1993; Dauer 1993; Dauer et al. 1998). Currently, several studies of the occurrence, impact, and efficacy of remediation strategies are underway in the Elizabeth River system.

Common Carp, Cyprinus carpo. Carp are the largest members of the minnow family. They are heavy-bodied fish and are usually bronze colored with large scales, each with a dark spot at the base. Their dorsal fin is long, containing one serrated spine in the front of the fin and more than 16 soft rays. They have two barbels on each side of the upper jaw. First introduced into the U.S. from Europe in 1876, the carp has since spread from coast to coast. They are widely distributed in New York. Carp tolerate most aquatic habitats, but prefer warm streams or lakes with muddy bottoms where they feed primarily on plankton, insects, and aquatic plants. Carp spawn in late spring. Their small, adhesive eggs are broadcast in shallow, weedy water.

[Common Carp]

Source: Photograph and text – Cornell Cooperative Extension.

Channel catfish, Ictalurus punctatus. Ictalurus is Greek, and punctatus is Latin, meaning "fish cat" and "spotted", respectively. Channel catfish are easily distinguished from all others, except blue catfish, by their deeply forked tail fin. Unlike flathead catfish the upper jaw projects beyond the lower jaw. Coloration is olive-brown to slate-blue on the back and sides, shading to silvery-white on the belly. Typically, numerous small, black spots are present, but may be obscured in large adults. The anal fin has 24-29 soft rays, as opposed to blue catfish which always have 30 or more rays in the anal fin.

[Channel Catfish]

Source: Photograph – Cornell Cooperative Extension; text – Texas Parts and Wildlife.