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Contaminant Trends in Great Lakes Fish


by
Robert J. Hesselberg
National Biological Service
John E. Gannon
National Biological Service
The Great Lakes region is home to many large industrialized cities and extensive agricultural areas that produce and use an array of potentially toxic chemicals. Some of these chemicals entering the lakes' food chain have been related to environmental health problems including poor egg-hatching success, reproductive abnormalities, and birth defects in fish, fish-eating birds, and mammals. Tumors and other deformities in some fish and wildlife species are also attributed to exposure to toxic contaminants. In addition, fish consumption advisories are issued annually by the Great Lakes' states and the Province of Ontario for certain fish species and larger sizes of Great Lakes fish that accumulate toxic contaminants.
To measure progress in reducing chemicals in the Great Lakes ecosystem, the National Biological Service's (NBS's) Great Lakes Science Center began a contaminant trend-monitoring program in Lake Michigan in 1969. The program was expanded in 1977 to include all of the Great Lakes and additional species of fish through a cooperative agreement between the NBS Great Lakes Science Center and the U.S. Environmental Protection Agency (USEPA), Great Lakes National Program Office. Fish are sampled for this program from 12 sites. All sites were sampled annually through 1982 and thereafter were divided into odd- and even-year sampling regimes. Results from these long-term monitoring programs are extremely valuable in understanding the dynamics of contaminants, developing predictive models for contaminant trends, and determining the effectiveness of regulatory programs.
This article presents data from the top predators sampled during even years for the NBS/USEPA monitoring program, lake trout (Salvelinus namaycush) or walleye (Stizostedion vitreum vitreum, Lake Erie only). In addition, information is presented on locations in the Great Lakes where tumors and other deformities in fish have been observed, indicating potentially contaminated sediments.

Methods
Lake trout from 600 to 700 mm (23.6-27.6 in) total length were collected from Lakes Superior, Michigan, Huron, and Ontario from even-year sampling sites by using gill nets (Fig. 1). Walleye from 400 to 500 mm (15.8-19.7 in) total length were collected from Lake Erie near Sandusky, Ohio, by using gill nets (Fig. 1). All fish were stored frozen until analyzed. Fish were prepared for analysis by thawing, compositing fish into five samples, and homogenizing. Contaminants were extracted and separated into nonpolar (polychlorinated biphenyls [PCBs]) and polar (DDT [sum of DDT, DDE, and DDD] and dieldrin) fractions and analyzed by a gas chromatograph equipped with an electron capture detector. Contaminants were reported as total DDT, total PCBs, and dieldrin.

Fig. 1. Sampling sites for the NBS/USEPA Fish Contaminant Monitoring Program and "hot spots" of sediment contamination where tumors and other deformities have been detected in fish.
Tumor surveys were conducted by the NBS Great Lakes Science Center and other agencies in highly industrialized rivers and harbors. Most of the work focused on the brown bullhead (Ameiurus nebulosus), a bottom-feeding fish especially exposed to tumor-causing chemicals in contaminated sediments.

Contaminant Trends
Results of DDT, PCB, and dieldrin trends during an approximately two-decade period are presented in Figs. 2-6. Data are from DeVault et al. 1985; Hesselberg et al. 1990; and DeVault and Hesselberg, in press. In general, concentrations of contaminants in fish consistently declined until the mid-1980's, but since then the downward trend has leveled off. Similar trends have been observed in fish in Canadian waters of the Great Lakes (Baumann and Whittle 1988).
Lake Michigan
Fig. 2. Contaminant results from Lake Michigan lake trout, 1970-90.
Contaminants were higher in Lake Michigan lake trout than in fish of any of the other Great Lakes. Both total DDT and PCBs declined (Fig. 2), yet total PCBs did not decline after the voluntary control in 1972 but did after the mandatory ban in 1976.
In lake trout dieldrin reached a high in 1978 and a low in 1987 (Fig. 2). Dieldrin is higher in Lake Michigan fish than in fish from the other Great Lakes, and changes in fish tissue concentrations do not follow use patterns for reasons that are not well understood.
Lake Superior
Total DDT and PCB concentrations in lake trout from Lake Superior were the lowest of all the Great Lakes and generally declined from 1977 to 1990 (Fig. 3). Dieldrin was always low and varied little from 1977 to 1990. Contaminant concentrations are lowest in Lake Superior because of the low density of agriculture and industry in the lake basin.

Fig. 3. Contaminant results from Lake Superior lake trout, 1977-90.
Lake Huron
Concentrations of total DDT and PCBs in lake trout from Lake Huron were intermediate between Lake Michigan and Lake Superior. Similar trends of declining concentrations of these chemicals were observed in Lake Huron (Fig. 4). Dieldrin concentrations were similar to Lake Superior but declined from a high in 1979 to a low by 1988. With the exception of the Saginaw Valley, both agriculture and industry are much less developed surrounding Lake Huron than Lake Michigan, thereby resulting in lower contaminants in Lake Huron fish.

Fig. 4. Contaminant results from Lake Huron lake trout, 1977-90.
Lake Ontario
The contaminants in Lake Ontario fish are relatively high (Fig. 5), second only to Lake Michigan. Trends in total DDT concentrations in lake trout from Lake Ontario were fairly constant from 1977 to 1990. Total PCBs in lake trout declined significantly from a high in 1977 to a low in 1990, a slower decline than in Lake Michigan. The relatively high contaminant concentrations in Lake Ontario fish are a result of the highly urbanized, industrial, and agricultural basin. In addition, it is the lowermost of the Great Lakes, receiving pollutants from upstream through the Niagara River. Dieldrin concentrations in lake trout from Lake Ontario reached a high in 1979 and then declined to a low by 1988.

Fig. 5. Contaminant results from Lake Ontario lake trout, 1977-90.
Lake Erie
Total DDT, PCB, and dieldrin concentrations in Lake Erie walleye (Fig. 6) were lower and more similar to concentrations in lake trout in Lake Superior than those of other Great Lakes. Total DDT and PCBs peaked in 1977 and declined to a low in 1982; no consistent trend was noted for dieldrin. Low concentrations of contaminants in Lake Erie were similar to those in Lake Superior even though Lake Erie is surrounded by the largest urbanized, industrial, and agricultural basin of all the Great Lakes. Lake Erie, however, is the shallowest of all the Great Lakes and contains the highest amount of particulate matter. Contaminants flush more quickly through the shallow lake and are removed from the water column as they adhere to particulate matter and settle to the bottom. These factors work together in reducing the amount of contaminants available to fish in Lake Erie.

Fig. 6. Contaminant results from Lake Erie walleye, 1977-90.
Contaminant Effects
Fig. 7. Lip tumor and stubbed barbels on a brown bullhead. Courtesy Marc Blouin, NBS/GLSC
Reduced reproductive success in fish-eating birds has been linked with DDT and PCBs (Giesy et al. 1994). As the concentrations of these contaminants have declined, populations of fish-eating birds such as the bald eagle (Haliaeetus leucocephalus) are beginning to recover in the Great Lakes basin. In lake trout, PCBs are also linked to reduced egg hatchability and may also be responsible for fry deformities and mortality (Mac et al. 1993). In spite of reductions in PCBs in lake trout in all of the Great Lakes, substantial natural reproduction occurs only in Lake Superior (Mac and Edsall 1991). The role of contaminants and other factors in lake trout reproductive problems in the other four Great Lakes is still under investigation.
Another fish health problem associated with toxic chemicals is found in Great Lakes harbors and tributaries where heavy industry was located (Baumann et al. 1991). Bottom sediments in these areas are heavily contaminated with polycyclic aromatic hydrocarbons (PAHs). Presence of liver tumors and other deformities such as lip papillomas, stubbed barbels, or skin discolorations in bottom-feeding fishes, such as the brown bullhead, have been linked to the presence of PAHs in the sediment (Baumann et al. 1991; Smith et al. 1994; Fig. 7). Tumors and other deformities have been detected in 15 locations (Hartig and Mikol 1992; Fig. 1).

Conclusions
The monitoring program for contaminants in Great Lakes fish has documented successful reduction of contaminants in response to usage bans for DDT and PCBs. Trends in dieldrin are less clear and concentrations of this pesticide remain especially high in Lake Michigan in comparison to the other Great Lakes. Fish communities are rebounding in some Great Lakes harbors, tributaries, embayments, and connecting channels that formerly were so contaminated that only the most pollution-tolerant organisms could survive. More reductions in contaminants are required, however. Monitoring results clearly indicate that the downward trend in contaminants leveled off in the mid-1980's, and resource-management agencies and research institutions are investigating the potential to further reduce sources of contamination in Great Lakes fish.
Reproductive problems, tumors, and other deformities are still being detected in certain fish and wildlife populations in most of the Great Lakes. Similarly, consumption advisories recommending restrictions on eating certain species and sizes of Great Lakes fish still remain. The United States and Canada have agreed upon a virtual elimination policy for toxic contaminants under the auspices of the Great Lakes Water Quality Agreement. Remedial action plans are being developed by federal and state agencies in cooperation with local municipalities and local citizens to eliminate beneficial use impairments in the most contaminated rivers, harbors, and bays in the Great Lakes. Continued long-term monitoring of contamination in fish is required to determine the success of these programs and to guide where further corrective actions may be necessary.
For further information:
Robert J. Hesselberg
National Biological Service
Great Lakes Science Center
1451 Green Road
Ann Arbor, MI 48105
References
Baumann, P.C., M.J. Mac, S.B. Smith, and H.C. Harshbarger. 1991. Tumor frequencies in walleye (Stizostedion vitreum) and brown bullhead (Ictalurus nebulosus) and sediment contaminants in tributaries of the Laurentian Great Lakes. Canadian Journal of Fisheries and Aquatic Sciences 48:1804-1810.

Baumann, P.C., and D.M. Whittle. 1988. The status of selected organics in the Laurentian Great Lakes: an overview of DDT, PCBs, dioxins, furans, and aromatic hydrocarbons. Aquatic Toxicology 11:241-257.

DeVault, D.S., and R.J. Hesselberg. 1995. Contaminant trends in lake trout and walleye from the Laurentian Great Lakes. Journal of Great Lakes Res. 21. In press.

DeVault, D.S., W.A. Willford, R.J. Hesselberg. 1985. Contaminant trends in lake trout (Salvelinus namaycush) from the upper Great Lakes. U.S. Environmental Protection Agency, Great Lakes National Program Office, Chicago, IL, EPA 905/3-85-001. 22 pp.

Giesy, J.P., J.P. Ludwig, and D.E. Tillitt. 1994. Deformities in birds of the Great Lakes region: assigning causality. Environmental Science and Technology 28:128A-135A.

 Hartig, J., and G. Mikol. 1992. "How clean is clean?" An operational definition for degraded areas in the Great Lakes. Journal of Environmental Engineering and Management 2:15-23.

Hesselberg, R.J., J.P. Hickey, D.A. Nortrup, and W.A. Willford. 1990. Contaminant residues in the bloater (Coregonus hoyi) of Lake Michigan, 1969-1986. Journal of Great Lakes Research 16:121-129.

Mac, M.J., and C.C. Edsall. 1991. Environmental contaminants and the reproductive success of lake trout in the Great Lakes: an epidemiological approach. Journal of Toxicology and Environmental Health 33:375-394.

Mac, M.J., T.R. Schwartz, C.C. Edsall, and A.M. Frank. 1993. PCBs in Great Lakes lake trout and their eggs: relations to survival and congener composition 1979-1988. Journal of Great Lakes Research 19:752-765.

Smith, S.B., M.A. Blouin, and M.J. Mac. 1994. Ecological comparisons of Lake Erie tributaries with elevated incidence of fish tumors. Journal of Great Lakes Res. 20:701-716.


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