Aromatic Hydrocarbons in Biota from the Detroit River and Western Lake Erie

J. Great Lakes Res. 23(2):160-168 Internal. Assoc. Great Lakes Res., 1997

Aromatic Hydrocarbons in Biota from the Detroit River and Western Lake Erie Chris D. Metcalfe l , Tracy L. Metcalfe l , Geoffrey Riddle2 , and G. Douglas Haffner2 1 Environmental

and Resource Studies Trent University Peterborough, Ontario K9J 7B8 2 Great Lakes Institute

University of Windsor Windsor, Ontario N9B 3P4 ABSTRACT. Polynuclear aromatic hydrocarbons (PAHs) and PCBs in zebra mussels were elevated to concentrations greater than 5,000 ng/g lipid and 15,000 ng/g lipid, respectively, at the Ambassador Bridge in the Detroit River and concentrations gradually declined at downstream locations, which included three stations in the western basin of Lake Erie (Middle Sister Island, East Sister Island, Pelee Island). PCB concentrations in zebra mussels collected at the stations in western Lake Erie were elevated relative to the concentrations in mussels at the upstream end of the Detroit River (Stoney Point). There is no evidence that PAH contamination in the Detroit River elevated PAH concentrations in zebra mussels in western Lake Erie relative to mussels at Stoney Point. Fluorescent aromatic compounds (FACs) representing metabolites of PAHs were analyzed in the bile of gizzard shad (Dorosoma cepedianum) and freshwater drum (Aplodinotus grunniens) collected from several sites in the Detroit River and western Lake Erie. Mean FAC concentrations were >1,000 ng BaP equivalents per mL of bile in fish from the Trenton Channel and Boblo Island in the Detroit River, but FAC data provided no evidence that fish captured at two sites in western Lake Erie (East Sister Island, Pelee Island) were exposed to elevated concentrations of PAHs through ingestion of contaminated biota or exposure to contaminated sediments. INDEX WORDS:

PAH, PCB, Detroit River, bile, zebra mussel, Lake Erie.

or PAHs (Fallon and Horvath 1985, Furlong et al. 1988). This class of organic contaminants, which includes several known genotoxic and carcinogenic compounds, is probably responsible for the mutagenic activity detected in sediments from the Detroit River (Maccubbin et al. 1991). The presence of aromatic-DNA adducts in liver tissue from Detroit River fish (Maccubbin et al. 1990), and the high prevalences of tumors in benthic fish species from the Detroit River (Maccubbin and Ersing 1990), are indicators that these compounds are affecting the health of fish from this region. Because PAHs are hydrophobic, suspended solids playa primary role in the transport of PAHs in the Great Lakes (Baker and Eisenreich 1989). Although there are data on the levels of PAHs in sediments within the Detroit River, the distribution of these com-

INTRODUCTION Sediments in the Detroit River system are contaminated with several classes of organic contaminants, including PCBs, organochlorine compounds, and polynuclear aromatic hydrocarbons (Fallon and Horvath 1985, Hamdy and Post 1985, Furlong et al. 1988). With an average flow of nearly 5,600 m 3 per second, the Detroit River has the potential to be a major source of many of the compounds that contaminate the sediments and biota of western Lake Erie. Field studies of the distribution of organic contaminants in clams, fish, and gulls from this region (Pugsley et al. 1985, Suns et al. 1985, Macdonald et al. 1992) clearly show that the Detroit River is an ongoing source of contamination. Parts of the Detroit River system are heavily contaminated with polynuclear aromatic hydrocarbons,

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Aromatic Hydrocarbons in Western Lake Erie pounds and their metabolites in biota from the Detroit River and western Lake Erie has not been adequately studied. Freshwater mussels, such as Elliptio compZanata, have been deployed in cages to monitor contaminants in the Great Lakes basin (Pugsley et al. 1985, Kauss and Hamdy 1985, Koenig and Metcalfe 1990). These bivalves bioconcentrate organic contaminants from water, sediment, and suspended particulates through their filter-feeding activities and they integrate contaminant fluctuations with time. In recent years, the invasion of the Great Lakes system with the zebra mussel, Dreissena poZymorpha, has provided an opportunity to use this bivalve species as an in situ biomonitoring organism (Fisher et aZ. 1993, Marvin et aZ. 1994). This species is particulari1y useful for monitoring contaminants in the aquatic environment because there are large numbers in the benthic food-web (Yankovich and Haffner 1993) and they have high filtration rates (Mackie 1991). Bivalve molluscs do not metabolize PAHs rapidly (Lee 1981), so it is not surprising that high concentrations of PAHs have been detected in zebra mussels from contaminated regions of the Great Lakes (Marvin et aZ. 1994). However, PAHs are metabolized and eliminated rapidly by fish (GokslZlyr and Farlin 1992, Niimi and Palazzo 1986). Therefore, analysis of fish bile for concentrations of aromatic metabolites is a better indicator of exposure to PAHs. Analysis of fluorescent bile metabolites has been shown to be an excellent biomarker for PAH contamination in flatfish from Puget Sound, Washington (Krahn et aZ. 1986) and in brown bullheads, Ameiurus nebuZosus, from the Great Lakes basin (Maccubbin et al. 1988, Balch et aZ. 1995). There is some evidence that tumor-bearing benthic fish in the Great Lakes are exposed to carcinogenic PAHs through the diet (Maccubbin et aZ. 1985). This introduces the possibility that benthic fish in the Detroit River and western Lake Erie region may be exposed to PAHs through consumption of contaminated benthic organisms, including zebra mussels. In this study, we determined the distribution of PAHs in zebra mussels at sampling stations extending from the upstream end of the Detroit River (i.e., Stoney Point) to the eastern margin of the western Lake Erie basin (i.e., Pelee Island). PCBs were also analyzed in these zebra mussel tissues. The purpose of this part of the study was to determine the spatial distribution of PAHs relative to PCBs in this area, and to evaluate the contribution of the Detroit River

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to PAH contamination in western Lake Erie. In addition, fluorescent aromatic compounds (FACs) representing metabolites of PAHs were analyzed in the bile of gizzard shad (Dorosoma cepedianum) and freshwater drum (ApZodinotus grunniens) that were collected from several sites in the Detroit River and western Lake Erie. The purpose of this part of the study was to determine whether benthic fish from the region show evidence of exposure to elevated concentrations of PAHs.

METHODS Sample Collection Zebra mussels with a valve length of 1-1.5 cm were collected from littoral regions (0-3 m depth) by removing them from hard substrates such as rocks and concrete. Mussels were collected while snorkeling or wading in May and June of 1994 at Stoney Point, Ambassador Bridge, and Turkey Island in the Detroit River and at Middle Sister Island, East Sister Island, and Pelee Island in western Lake Erie (Fig. 1). After collection, mussels were returned to the laboratory at the University of Windsor where they were immediately shucked, without a depuration period. The shucked soft tissues from each site were pooled into replicate samples (n = 3) of approximately 10 g wet weight and were wrapped in solvent-washed aluminum foil before storage at - 4°C. Gizzard shad (n = 13) and freshwater drum (n = 13) were collected during May to August, 1994 using overnight sets of 4- and 4.5-inch gill nets. The sites sampled were Pelee Island, East Sister Island, and Middle Sister Island in the western basin of Lake Erie, and Boblo Island, Grassy Island, and the Trenton Channel in the lower Detroit River (Fig. 1). Nets were checked as early as possible on the morning after setting and captured fish were immediately sampled for bile. Freshwater drum were between 25-40 cm in length and there were 11 females and 2 males sampled. Gizzard shad were 31-42 cm in length and the sex of these fish was not identified. The liver and gall bladder were exposed through an incision on the ventral region of the fish and a bile sample (1-2 mL) was removed by puncturing the gall bladder with a 10 mL tuberculin syringe with a 23 G needle. Bile was immediately stored in plastic provials on dry ice and returned to the laboratory, where it was stored at -60°(:.

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Lake St. Clair

5!Legend To Sampling Sites 1 2 3 4 5 6

Stoney Point Ambassador Bridge Turkey Island Middle Sister Island East Sister Island Pelee Island

Lake Erie Western Basin

FIG 1. Map of study area showing sampling sites in the Detroit River and western Lake Erie for collection of zebra mussels (sites 1-6) and collection of bile from fish (Boblo Island, Grassy Island, Trenton Channel, East Sister Island, Pelee Island).

Chemical Analysis Organic contaminants were extracted from zebra mussels by mixing the tissue with sodium sulfate (approximately 30 g) in a 150 mL beaker and homogenizing this mixture with 100 mL of methylene chloride (OCM) in a polytron homogenizer. The OCM was decanted off and the mixture was homogenized with a further 75 mL of OCM. The extraction was repeated twice more with 50 mL and 35 mL, respectively, of OCM. The OCM extracts were passed separately through a Buchner funnel packed with a solvent-washed glass fibre filter (Whatman GF-A3H) topped with sodium sulphate. Finally, the tissue mixture was scraped into the Buchner funnel and rinsed with a further 50 mL of OCM. Extracts were prepared for analysis of PAH

and PCB analytes using methods described previously (Harris et al. 1994, Bennett et al. 1996). Briefly, lipids were separated from extracts by gel permeation chromatography (GPC) on Biobeads SX3 (BioRad). Lipids eluted from the GPC column were weighed to determine the lipid content of the mussels. The samples were then fractionated by column chromatography on activated silica gel (Baker, 60-200 mesh). Elution with 40 mL of hexane produced a fraction containing primarily PCBs and further elution with 70 mL of 50:50 hexane:OCM yielded a fraction containing PAHs. The fractions were rotary evaporated to a volume of approximately 2 mL and further concentrated under a stream of nitrogen to a volume appropriate for analysis. The individual PCB congeners analyzed in mus-

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Aromatic Hydrocarbons in Western Lake Erie sel samples were (in order GC of elution) 18, 31, 28, 52, 49, 47, 44, 66, 101, 99, 87, 110, 149, 151, 118, 153, 105, 138, 156, 180, 170, 199, 196, 195, 194, and 209. These congeners were analyzed by high resolution gas chromatography using a Varian 3500 GC with a 60 m DB-5 column and a 63Ni electron capture detector, using instrument conditions described previously (Harris et ai. 1994). PCB congeners were quantitated against a PCB standard (CLB -1) purchased from the National Research Council, Halifax. "Total PCBs" were calculated as the sum of the concentrations of all PCB analytes. PAH compounds analyzed were the 16 "priority PAHs" identified by the USEPA, which include napthalene, acenapthylene, acenapthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo [a] anthracene, chrysene, benzo [b] fl uoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-c,d]pyrene, dibenzo[a,h] anthracene, and benzo[g,h,i]perylene. These compounds were analyzed by gas chromatography-low resolution mass spectrometry in selected-ion mode (GC-LRMSSIM) using a Hewlett Packard 5890 Series II gas chromatograph equipped with a 30 m DB-5 column and a Hewlett Packard 5971A mass selective detector. GC-MS conditions and ions monitored for PAH analytes were described previously (Bennett et ai. 1996). PAH analytes were quantitated against a PAH standard purchased from Supelco. The two benzofluoranthene isomers (b and k) could not be resolved chromatographically, so they were quantitated as

total fluoranthenes. "Total PAHs" were calculated as the sum of the concentrations of all PAH analytes. PCB and PAH concentrations were calculated as ng/g wet weight and were also lipid-normalized to ng/g lipid. Statistical analysis of analytical data was conducted by t-tests (a = 0.05) of mean total PAH and PCB concentrations (wet weight and lipid normalized) in mussels at paired sites. FACs in bile were analyzed by a modification of the assay described by Krahn et ai. (1986), as described previously by Balch et al. (1995). Briefly, unhydrolized bile was analyzed with a Waters mode1600E HPLC with a model 470 scanning fluorescence detector and a 5 flm C 18 reverse-phase column (0.46 cm x 25 cm ID). The FACs were eluted with a solvent gradient varying from 100% of 0.5% acetic acid in water (Solvent A) to 100% methanol (Solvent B). Total fluorescence was measured at an excitation/emission wavelength pair of 380/430 nm, which is specific for benzo[a]pyrene (BaP). The peak areas of samples were quantitated against the peak areas for a BaP standard (0.4 ng/flL). Concentrations of total FACs were quantitated in units of ng of BaP equivalents per mL of bile.

RESULTS Zebra mussels collected at the three Detroit River stations had higher lipid contents (i.e., > 1.2%) than mussels collected at the three sites in western Lake Erie (Table 1). Since bioaccumulation of lipophilic

TABLE 1. Mean and standard deviation (in brackets) of% lipid and total PAH and total PCB concentrations in zebra mussel samples (n = 3) from six sites in the Detroit River and western Lake Erie. PAH and PCB concentrations are presented on both a wet weight and a lipid-normalized basis. Stoney Pt.

Mean Concentration (ng/g) Ambassador Br. Turkey Is. M. Sister Is.

% Lipid

1.21 (0.23)

1.79 (0.08)

Total PAHs ng/g wet wt.

19.8 (7.7)

98.7 (2.3)

67.6 (15.4)

Total PAHs ng/g lipid

1,619.6 (372.9)

5,164.4 (40.9)

Total PCBs ng/g wet wt.

17.1 (4.4) 767.2 (92.0)

Total PCBs ng/g lipid

1.45 (0.08)

0.78 (0.13)

E. Sister Is.

Pelee Is.

1.07 (0.15)

0.85 (0.23)

16.7 (10.1)

13.9 (6.6)

12.6 (9.7)

3,158.5 (432.5)

1,375.6 (462.4)

789.8 (370.1)

1,840.3 (1,465.7)

301.2 (185.9)

51.7 (7.8)

28.3 (7.5)

23.8 (11.9)

20.0 (14.7)

15,103.0 (8,767.3)

3,398.3 (107.3)

3,659.3 (481.5)

2,442.3 (1,326.2)

4,971.2 (1,017.6)

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TABLE 2. Mean proportions (%) of PAH analytes relative to total PAHs in zebra mussel samples (n = 3) from six sites in the Detroit River and western Lake Erie. Stoney Pt.

Mean Proportions (%) Ambassador Br. Turkey Is.

Naphthalene Acenaptylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Benz[a]anthrac. Chrysene Benzofluoranth. 1 Benzo[a]pyrene Indenopyrene Dibenzanthrac. Benzoperylene

1.39 0.64 0.42 0.54 1.17 0.56 1.9 1.32 12.34 6.26 1.84 1.78 29.32 11.12 14.64 9.48 7.26 16.66 16.6 22.08 9.62 18.19 3.08 7.9 0.41 0 0 0 0 3.49 lTotal fluoranthenes are reported, as benzo[b]fluoranthene

contaminants such as PARs and PCBs is partially dependent on the lipid content of biota, lipid-normalized monitoring data (ng/g lipid) may give a better indication of trends in contaminant concentrations. Total PAR concentrations in zebra mussels varied between 12.6 and 98.7 ng/g wet weight and between 789.8-5,164.4 ng/g lipid in the study area (Table 1). There were significantly higher wet weight and lipid-normalized PAR concentrations in mussels collected at the Ambassador Bridge station in the Detroit River relative to mussels from the upstream location at Stoney Point. Downstream of the Ambassador Bridge, there was a trend of declining PAR concentrations with distance downstream. The wet weight and lipid-normalized PAR concentrations in mussels from the Turkey Island station were significantly lower than concentrations in mussels from the station upstream (i.e., Ambassador Bridge) and the station downstream (i.e., Middle Sister Island). The mean wet weight and lipid-normalized PAR concentrations in mussels from the three stations in western Lake Erie (i.e., Middle Sister, East Sister, and Pelee Island) were not significantly different from each other. There was considerable variability in the lipid-normalized PAR concentrations in mussel samples collected from Pelee Island (Table 1). There were no significant differences in the mean PAR concentrations in mussels from all western Lake Erie stations relative to mussels from the Stoney Point station at the upstream end of the Detroit River.

M. Sister Is.

E. Sister Is.

0.33 4.85 1.54 0.54 0.99 0.68 0.5 0.7 0.22 1.73 2.01 0.73 16.02 9.94 3.4 2.19 1.38 1.1 29.53 16.55 10.68 17.03 8.02 4.45 7.63 0 0 11.95 19.13 24.8 28.61 9.3 50.07 3.05 6.14 2.24 0.22 1.65 0 0 0 0 0 0 0 and benzo[k]fluoranthene were not resolved.

Pelee Is. 8.75 0.98 1.04 .32 7.53 1.34 13.62 5.66 0 35.88 16.39 5.08 1.44 0 0

The dominant PAR compounds in these samples were phenanthrene, fluoranthene, chrysene, and benzofluoranthenes (Table 2). There appeared to be a trend to higher proportions of naphthalene, acenapthylene, chrysene, and benzofluoranthenes in mussels from the Lake Erie stations. On the other hand, proportions of benz[a]anthracene were relatively high (7-18%) at the Detroit River stations, while this compound was not detected in any of the mussel samples from western Lake Erie (Table 2). The trend in concentrations of total PCBs in mussel samples was consistent with the PAR data. Mean total PCB concentrations were once again highest in mussels from the Ambassador Bridge station and declined gradually with distance downstream (Table 1). Concentrations varied between 17.1-3,091.2 ng/g wet weight and 767.2-15,103 ng/g lipid. There were significant differences between the mean wet weight and lipid-normalized PCB concentrations in mussels collected at Stoney Point and the Ambassador Bridge. There were significantly lower mean PCB concentrations on a wet weight and lipid-normalized basis in mussels collected from the Turkey Island station relative to the Ambassador Bridge mussels. For mussels collected at Turkey Island and Middle Sister Island, the mean PCB concentrations at the two stations were significantly different on a wet weight basis, but not on a lipid-normalized PCB basis. There were no significant differences between the mean wet weight and lipid-normalized PCB concentrations in mussels

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Aromatic Hydrocarbons in Western Lake Erie

20

greater than the mean lipid-normalized PCB concentration in mussels from Stoney Point. All PCB analytes were detected in the mussels, but the dominant PCBs in all mussel samples were congeners 101, 110, 153, 138, and 180. However, as illustrated in a comparison between PCB congener patterns in zebra mussels at the Ambassador Bridge and East Sister Island stations (Fig. 2), the mussels from the Detroit River tended to have higher proportions of some tetra- and pentachlorobiphenyls (e.g., congeners 52, 101, 110, 118), while the Lake Erie mussels tended to have higher proportions of trichlorobiphenyls (e.g., congeners 18, 31, 28) and hexa- and heptachlorobiphenyls. There were only limited numbers of gizzard shad (n = 13) and freshwater drum (n = 13) captured for bile analysis, and these fish species were captured simultaneously at only one site; the Trenton Channel in the Detroit River. As summarized in Table 3, both gizzard shad and drum from the Trenton Channel had the highest mean concentrations of bile FACs. The highest FAC concentration measured in the survey was in the bile of a gizzard shad captured in the Trenton Channel (12,289.6 ng/mL BaP equivalents). Mean bile FACs were also high in drum from Boblo Island in the Detroit River. Gizzard Shad captured at Turkey Island (Detroit River)

PCB Congener Patterns Zebra Mussels -,---~-------~c----------~

-

;g 15 o c:

~ 10 o

c.

~

0..

5

[•

Ambassador Sr. If§ East SisteriS."]

FIG. 2. Proportions (%) of congeners relative to total PCBs in zebra mussels collected at the Ambassador Bridge site in the Detroit River and the East Sister Island site in western Lake Erie.

from the Middle Sister, East Sister, and Pelee Island stations in western Lake Erie. Mean lipid-normalized PCB concentrations in mussels from all stations in western Lake Erie were significantly

TABLE 3. Mean, standard deviation about the mean, and the range (in brackets) of concentrations of fluorescent aromatic compounds (FACs) in the bile of gizzard shad and freshwater drum collected at stations in the Detroit River and western Lake Erie. FAC concentrations are reported as ng of BaP equivalents per mL of bile. FACs (ng/ml BaP) ~ean

S.D.

Species

N

(Range)

FWDrum G. Shad

1 6

1,220.9 3,921.6 (101.9-12,289.6)

Boblo Island

FWDrum

3

1,596.0 (925.3-2,452.9)

424.1

Grassy Island

FWDrum

3

442.9 (332.8-539.1)

20.7

Turkey Island

G. Shad

Western Lake Erie: East Sister Island

FWDrum

6

188.2 (58.6-447.4)

19.8

Pelee Island

G. Shad

6

128.5 (35.6-239.8)

32.4

Location

Detroit River: Trenton Channel

875.3

1l0.4

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Metcalfe et al.

and Pelee Island (Lake Erie), and freshwater drum captured at Grassy Island (Detroit River) and East Sister Island (Lake Erie) had mean concentrations of FACs in the bile that were an order of magnitude lower than the mean bile FACs in fish captured at Boblo Island and the Trenton Channel.

DISCUSSION The concentrations of PAHs and PCBs in the soft tissues of zebra mussels from the most contaminated site in this survey (i.e., Ambassador Bridge) were in the 0.1- 0.3 ppm range on a wet weight basis and approximately 5 and 15 ppm, respectively, on a lipid weight basis. These PCB concentrations are consistent with previously published contaminant data for zebra mussels in the Lake St. Clair-Lake Erie corridor (Morrison et aZ. 1996) and other moderately contaminated regions. PCB concentrations in zebra mussels from the Mosel River in Europe varied between 2.5-10 ppm on a lipid weight basis (Mersch et at. 1992). In Lake Cretail, France, PCB concentrations in zebra mussels were all below 1 ppm wet weight (Chevreuil and Testard 1991). PCB concentrations in zebra mussels from contaminated regions of the St. Lawrence River ranged from 0.1-2 ppm wet weight (Pilote 1995). PAH concentrations in zebra mussels from the highly contaminated Hamilton Harbour in western Lake Ontario varied between approximately 0.3-10 ppm wet weight in homogenates of whole zebra mussels that included the shells (Marvin et aZ. 1994). It is likely that concentrations of both PAHs and PCBs would have been higher in zebra mussels collected near more grossly contaminated regions of the Detroit River. For example, PAHs have been detected at almost part per thousand concentrations in sediments from some parts of the Trenton Channel (Furlong et aZ. 1988), and freshwater mussels (E. compZanata) deployed near the River Rouge just south of the Ambassador Bridge accumulated very high concentrations of PCBs (Kauss and Hamdy 1985). Unfortunately, attempts to obtain mussel samples from these grossly contaminated regions were not successful, perhaps because poor water quality conditions at these sights were not suitable for the colonization and survival of zebra mussels. The trends in concentrations of PCBs in zebra mussels are consistent with inputs of these hydrophobic contaminants into the Detroit River. PCBs were analyzed along with PAHs in mussel tissues because the former compounds are more resistent to environmental degradation and metabolic

biotransformation, and it is known that tissue concentrations of PCBs in marine mussels are highly correlated with surrounding dissolved PCB concentrations (Bergen et aZ. 1993). Lipid-normalized PCB data indicate that the mean PCB concentration in zebra mussels at Pelee Island was significantly elevated above the mean PCB concentration in mussels from the most upstream station on the Detroit River (i.e., Stoney Point). This indicates that PCB contamination in the Detroit River contributes to the PCB burden in zebra mussels from western Lake Erie, even at the eastern boundary of this basin. In contrast to the PCB data, there was no significant difference between the mean lipid-normalized PAH concentrations in mussels from Stoney Point and mussels from the stations in western Lake Erie. Mussels with elevated PAH concentrations are primarily confined to the Detroit River. There is no evidence that PAH contamination in the Detroit River contributes to increased PAH concentrations in mussels from western Lake Erie relative to the PAH concentrations in mussels from the upstream end of the Detroit River. There were differences observed in the proportions of individual PAH compounds and PCB congeners in Detroit River mussels in comparison to mussels from western Lake Erie. It is possible that additional inputs of contaminants into the Detroit River between the Turkey Island station and Lake Erie changed the pattern of PAHs and PCBs entering Lake Erie. Alternatively, physicochemical processes such as volatilization, photodegradation, and sedimentation could have affected contaminant patterns, or the partitioning of PAHs and PCBs between water and mussel tissues. It was hypothesized that benthic fish species could be exposed to elevated concentrations of PAHs in the Detroit River and western Lake Erie. This would be especially true if consumption of contaminated benthic organisms, including zebra mussels, was a vector for PAH bioaccumulation in these benthic fish (Maccubbin et aZ. 1985). There is anecdotal evidence that freshwater drum consume zebra mussels in the Detroit River-Lake Erie region. Gizzard shad are detritivores, and Mundahl (1991) estimated that these species process a dry mass of sediments equivalent to 13% of their biomass each day. Therefore, there is potential for accumulation of contaminants by gizzard shad through direct ingestion of sediment, and consumption of infauna. Mean bile FACs in gizzard shad and freshwater

Aromatic Hydrocarbons in Western Lake Erie drum were elevated to concentrations> 1,000 ng BaP equivalents per mL of bile at the Trenton Channel and Boblo Island sites. Krahn et al. (1986) reported mean FAC concentrations in the bile of English sole from contaminated sites in Puget Sound, Washington ranging from 1,300-2,100 ng/mL BaP equivalents. Brown bullheads collected from the highly contaminated Buffalo River had mean FAC concentrations ranging from 350-47,600 ng/mL BaP equivalents (Maccubbin et ai. 1988). Bullheads from the contaminated Black Creek and the Cuyahoga River in Ohio had mean bile FAC concentrations of 246 ng/mL and 352 ng/mL BaP equivalents, respectively (Lin et ai. 1994). In this latter study, bile FACs in bullheads from a reference location in Old Woman Creek, Ohio were 63 ng/mL BaP equivalents. Although it is difficult to compare FAC data for different fish species, it appears that bile FACs in fish from sites in western Lake Erie were near the levels expected in fish from relatively uncontaminated locations. Elevated bile FACs in fish from several locations in the Detroit River, and in particular, the highly contaminated Trenton Channel indicated that these fish had been exposed to high concentrations of aromatic contaminants. In conclusion, it appears that discharges of contaminants in the Detroit River increase the PCB burdens in zebra mussels in western Lake Erie relative to upstream sites in the Detroit River. However, PAH concentrations in zebra mussels from western Lake Erie do not appear to be elevated relative to concentrations in mussels from Stoney Point. Concentrations of both PAHs and PCBs were elevated in mussels collected at two sites in the industrialized region of the Detroit River. There is no evidence that benthic fish in western Lake Erie are exposed to elevated concentrations of PAHs through ingestion of contaminated biota or exposure to contaminated sediments. Benthic fish were obviously exposed to high concentrations of PAHs in grossly contaminated regions of the Detroit River, such as the Trenton Channel and Boblo Island.

ACKNOWLEDGMENTS This work was funded through a Great Lakes University Research Fund (GLURF) Grant by Environment Canada and the Natural Sciences and Engineering Research Council (NSERC) of Canada, with GDH as the Principal Investigator. Brenda Koenig prepared samples for analysis and inter-

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preted analytical data. PAHs were analyzed by Erin Bennett.

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