USGS



BIOLOGICAL AND ECOTOXICOLOGICAL CHARACTERISTICS OF TERRESTRIAL VERTEBRATE SPECIES RESIDING IN ESTUARIES

Double-Crested Cormorant Double-Crested Cormorant photo by Jeff Spendelow
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Biological Characteristics 

Species

Phalacrocorax auritus, 76-89 cm in length, is an all black bird with a thin yellow bill hooked at its tip. Males tend to have a greater average mass (1.8 kg) than females (1.5 kg), though sexes are generally similar in appearance (Bull and Farrand, 1977; Dunning, 1993).

Status in Estuaries

A colonial breeder that may nest with other species, this species can be found either in coastal areas or freshwater areas located further inland. Nests are found on the ground, on cliffs, or in trees (Spendelow and Patton, 1988). Typical clutch size is 4 eggs, but may range from 3-6 eggs (Lewis, 1929). Young are altricial (Ehrlich et al., 1988). This maximum age for this cormorant recorded from nature is 17 years (Clapp et al., 1982).

Abundance and Range

Double-crested cormorants breed from Alaska and Newfoundland south to Mexico (Bull and Farrand, 1977).  Wintering occurs to southern Alaska and Long Island, new York.  More than 740,000 individuals are estimated in North America (NACWCP, 2001).

Site Fidelity

Breeding birds typically use the same colony and nesting location year after year (Lewis, 1929).

Ease of Census

Simple.

Feeding Habits

Generalist. This species prefers to feed in moderately shallow water (less than 30 feet) (Clapp et al., 1982). Its diet is predominantly composed of fish, though it will take crustaceans, aquatic insects and plants (Clapp et al., 1982). Specific prey include sculpins, shrimps, sandlance, insects, herring, eel, cod, crustaceans, and mollusks (Lewis, 1929).


Double-Crested Cormorant Contaminant Exposure Data

I.

Organochlorine Contaminants

A.

Concentrations in Adults, Juveniles, and Nestlings

1.

DCCs were collected from Muscongus Bay, Maine in 1966-67 (Kury, 1969). In 1966, 25 adults contained the following mean concentrations of DDE: 1.5 mg/g brain, 6.5 mg/g gonads, and 3.0 mg/g heart. In 1967, 18 adults contained a mean DDE concentration of 0.34 mg/g in brain and of 23 pooled samples of nestlings (representing 89 birds), only 5 had measurable concentrations of DDE, ranging from a trace to 0.29 mg/g.  Analysis of the habitat and distribution of contaminants in the birds indicated that exposure to the pesticides occurred in some other area, possibly its wintering grounds in Florida.

2.

DCCs were collected from the Bay of Fundy in the Gulf of Maine area (Zitko et al., 1972; Zitko and Hutzinger, 1972). Mean concentrations of PCB (Aroclor 1254) were 3.38 mg/g wet weight muscle, 2.13 mg/g liver, 38 mg/g subcutaneous fat, and 52 mg/g abdominal fat. Mean concentrations of DDE were 8.40 mg/g muscle, 4.16 mg/g liver, 164 mg/g subcutaneous fat, and 162 mg/g abdominal fat.

3.

One DCC collected between 1969 and 1972 from Alberta contained geometric mean liver concentrations of 0.12 mg/g dry weight DDE and 0.004 mg/g PCB (Gilbertson and Reynolds, 1974).

4.

Adult DCCs were collected from rookeries on Dry Lake and South Waubay Lake, South Dakota, for analysis of chlorinated hydrocarbons and Hg (Greichus et al., 1973). Average total concentrations of organochlorine pesticides in "body", muscle, and liver were 10.7, 6.7, and 3.6 mg/g wet weight, respectively. Concentrations of individual pesticides were predominately in the DDT family. Mean concentrations of these compounds were 107.84 mg/g DDE, 2.11 mg/g DDD, and 2.16 mg/g parent DDT in fat, and 2.70 mg/g DDE, 0.44 mg/g DDD and 0.31 mg/g parent DDT in liver. Dieldrin concentrations were 1.38 mg/g in fat, 0.13 mg/g in liver, and 0.12 mg/g in brain. Heptachlor epoxide and lindane were detected at concentrations of 0.25 mg/g and 0.26 mg/g in fat, and <0.05 mg/g in liver and brain. PCB residues in fat, liver, brain and bodies were 22.4, 2.0, 1.3, and 4.6 mg/g, respectively.

5.

Organochlorines were measured in two DCCs collected from Florida in 1974 (Johnston, 1976). Concentrations detected in adipose tissue were 0.70 and 2.21 mg/g wet weight DDE, and 0.79 and 3.01 mg/g total DDT. In uropygial glands, values were 0.73 and 1.38 mg/g DDE, and 1.23 and 1.68 mg/g total DDT. Dieldrin was detected in the uropygial gland only of one bird at 0.34 mg/g. PCB was not detected.

6.

Adult DCCs were collected in November, 1982, in the Houston Ship Channel, Texas, shortly after completion of the fall migration (N=10), and in late February, 1983, after overwintering (N=10) (King et al., 1987). Carcasses were analyzed after removal of skin, bills, feet, and gastrointestinal tract. DDE was detected in all samples, at a geometric mean (range) of 0.66 (0.21-2.5) mg/g wet weight in the November samples and 0.93 (0.4-2.3) mg/g in the February samples. DDD, dieldrin, chlordane, HCB, and heptachlor epoxide were not detected in November samples, but were detected in some of the February samples (maximum concentrations were 0.25 mg/g for dieldrin and 0.28 mg/g for HCB). PCBs were found in 9 of 10 samples in November, 1.54 (0.8-6.0) mg/g, and in all samples collected in February, 1.58 (1.1-3.3). Mean and range of PCS were 0.13 (0.17-0.4) mg/g in 6 of 10 November samples and 0.34 (0.18-0.68) mg/g in all 10 February samples.

7.

Nestling DCC (N=3) were collected in 1983 from Spider Island and Gravelly Island in Lake Michigan for analysis of organochlorine contaminants (Stalling et al., 1985). Mean concentrations of contaminants detected were 4 ng/kg TCDD, 25 ng/kg total PCDDs, 2 ng/kg 2,3,7,8-TCDF, 10 ng/kg total PCDFs, and 1.0 DDE mg/kg non-ortho PCB.

8.

As part of a more extensive 1984 evaluation of nesting success and analysis of eggs, residues of chlorinated hydrocarbons were determined in breast muscle of 3 adult DCCs found dead near Williamson Rocks in Washington (Henny et al., 1989). Concentrations ranged from 0.14 to 0.35 mg/g wet weight DDE and from 0.49 to 0.73 mg/g PCB.

9.

Eggs (N=127) and juvenile (N=84) DCCs were collected in 1984 and 1985 from ten aquatic systems in Alberta and one in Saskatchewan (Somers et al., 1993). The geometric means of DDE and PCB residues in young were 0.95 and 0.94 mg/g wet weight lipid, respectively. HCB, BHC, oxychlordane, heptachlor epoxide, dieldrin, mirex, endrin were not detected in young.

10.

Adult DCC (N=20) were collected from the Caimanero Lagoon in northwest Mexico in 1986 (Mora and Anderson, 1991). Residues were determined in carcass samples after removing feathers, wings, head, feet and stomach contents. DDE was found in all birds at a geometric mean (range) concentration of 5.05 (0.77-13.46) mg/g wet weight. Parent DDT was found in 19 birds with values ranging from 0.007-0.041 mg/g. Dieldrin was detected in 14 specimens with concentrations ranging from 0.004-0.079 mg/g. PCBs were found in less than 50% (7/20) of the birds with a mean value of 0.116 mg/g. Values of HCH, detected in 19 birds, were low, ranging from 0.008-0.071 mg/g. Concentrations of HCB, DDD, oxychlordane, heptachlor epoxide, endosulfan, and endrin were <0.1 mg/g.

11.

In 1989, DCC eggs and chicks were collected from 8 sites in the Great Lake region and assayed for total PCBs, and TCDD-equivalents using the in vitro H4IIE rat hepatoma bioassay (Jones et al., 1994). The TCDD-equivalents ranged from 141.7 to 382.3 pg/g wet weight in eggs and from 17.9 to 398.9 pg/g in chicks from the 7 sites. Concentrations of both PCBs and TCDD-equivalents decreased immediately upon hatching of the chicks. Rates of accumulation of both contaminants in growing chicks were directly correlated with concentrations in forage fish consumed by the chicks.

12.

Mean (standard deviation) organochlorine residues found in DCC livers (N=3) collected from Clear Lake, California, in 1993, were 0.204 (0.266) mg/g wet weight (Wolfe and Norman, 1998).

13.

In 1994 and 1995, DCC 10-day old chicks were collected from Wisconsin, Minnesota, and South Dakota (Custer et al., 2001). Geometric mean (range) total PCB concentrations (N=10/colony) at Marsh Lake & Piyas Lake, Spider Island, Hat Island, and Cat Island were, respectively: 0.13 (0.02-0.44), 1.64 (1.2-2.3), 1.89 (1.6-2.6), and 3.45 (2.6-5.0) mg/g wet weight. cis-Nonachlor concentrations were less than 1 mg/g in chicks at all test sites and were not detected in samples from the reference sites (Marsh and Piyas Lakes).

Geometric mean dieldrin concentrations (N=5/colony/year) in 1994 were 0.012, 0.118, 0.083, and 0.067 mg/g at Piyas Lake, Spider Island, Hat Island, and Cat Island, respectively, and in 1995 were 0.0006, 0.061, 0.077, and 0.051 mg/g at Marsh Lake, Spider Island, Hat Island, and Cat Island, respectively. Geometric mean heptachlor epoxide concentrations (N=5/colony/year) in 1994 were 0.006, 0.035, 0.025, and 0.018 mg/g at Piyas Lake, Spider Island, Hat Island, and Cat Island, respectively and in 1995 were ND, 0.020, 0.020, and 0.012 mg/g at Marsh Lake, Spider Island, Hat Island, and Cat Island, respectively. Geometric mean oxychlordane concentrations (N=5/colony/year) in 1994 were 0.006, 0.020, 0.017, and 0.015 mg/g at Piyas Lake, Spider Island, Hat Island, and Cat Island, respectively and in 1995 were ND, 0.011, 0.012, and 0.011 mg/g at Marsh Lake, Spider Island, Hat Island, and Cat Island, respectively. Geometric mean DDE concentrations (N=5/colony/year) in 1994 were 0.177, 0.549, 0.652, and 0.530 mg/g at Piyas Lake, Spider Island, Hat Island, and Cat Island, respectively and in 1995 were 0.126, 0.379, 0.463, and 0.547 mg/g at Marsh Lake, Spider Island, Hat Island, and Cat Island, respectively. Geometric mean Van den Berg TEQs in 1994 were 1, 30, 46, and 48 pg/g at Piyas Lake, Spider Island, Hat Island, and Cat Island, respectively and in 1995 were 1, 9, 17, and 24 pg/g at Marsh Lake, Spider Island, Hat Island, and Cat Island, respectively.

14.

In 1995, 20 DCC hatchlings, ages 0 11 days, were collected from Dor Lake, Saskatchewan, Canada and raised at the Animal Care Unit, University of Saskatchewan (Kuiken et al., 1999).  These birds were euthenized at ages 5 to 27 weeks.  In 1992, ten four-week-old DCC with normal bills were collected from each of the following places, and euthanized: Churchill Lake, Saskatchewan, Canada; Pigeon Island, eastern Lake Ontario, Canada; Little Gull Island, upper Green Bay, Lake Michigan, USA.  Total PCBs in livers of captive cormorants with a normal bill (n = 1) were 0.085 mg/g wet weight; DDE was 0.011 mg/g.  Total PCBs in livers of captive cormorants with crossed-bills were 0.118 0.013 mg/g, and DDE was 0.013 0.001 mg/g.  Total PCBs in livers of free-living cormorants collected at Churchill Lake, Lake Ontario, and Lake Michigan, respectively, were: 0.027, 0.658, and 0.656 mg/g (each number represents an average from 10 birds).  DDE in livers of free-living cormorants collected at Churchill Lake, Lake Ontario, and Lake Michigan, respectively, were:  0.018, 0.162, and 0.131 (each number represents an average from 10 birds). 

B.

Concentrations in Eggs and Embryos

1.

DCC eggs (N=89) were collected from several colonies in the Prairie states and Canadian provinces in the vicinity of the Great Lakes (Anderson et al., 1969). Mean concentrations detected in 35 egg pools were 10.4 mg/g wet weight DDE and 8 mg/g PCBs. DDD and DDT were only rarely detected.

2.

DCC nestlings and eggs were collected from Muscongus Bay, Maine in 1966-67 (Kury, 1969). In 1966, 24 eggs contained a mean of 1.5 mg/g DDT, 0.7 mg/g DDD, and 6.2 mg/g DDE. In 1967, 11 eggs averaged 4.5 mg/g DDT, 1.5 mg/g DDD, and 7.6 mg/g DDE. In the same year, of 23 samples (representing 89 nestlings), only 5 had measurable concentrations of DDE, ranging from a trace to 0.29 mg/g.

3.

Composite samples of 10 DCC eggs collected from sixteen colonies in Alberta and Saskatchewan in 1968 and 1969 were analyzed for organochlorine residues (Vermeer and Reynolds, 1970). Mean concentrations for each colony ranged from 3.43-9.00 mg/g wet weight DDE and from 0.112-0.681 mg/g dieldrin. Heptachlor epoxide was measured in ten of the colonies and means ranged from 0.015-0.075 mg/g. b-BHC was detected in eight of ten colonies evaluated, and means ranged from 0.065-0.280 mg/g. Variation in DDE was calculated in one of colonies, Lake Therien, which had a mean level of 3.57 mg/g, a range 1.5-6.4 mg/g, and a coefficient of variation of 41.65.

4.

Crushed and intact eggs were collected in 1969 in southern California and northwest Baja California from the west inlet of Anacopa Island, South Los Coronados Island, and San Martin Island (Gress et al., 1973). Yolk of intact eggs was analyzed for chlorinated hydrocarbon residues. Mean (range) DDE residues in yolk lipids were 754 (510-1000) mg/g in the eggs from Anacapa Island, 574 (180-1300) mg/g from Los Coronados Island and 41.4 (24-63) mg/g in eggs from the San Martin colony. PCB was detected at concentrations of 87 (55-130), 422 (66-1100), and 17.6 (12-25) mg/g, respectively. DDD was present in eggs from the Anacapa Island (2.1, 0.66-6.8 mg/g) and Los Coronados Island (13.8, 3.6-36 mg/g) but not detected in samples from San Martin. Parent DDT was found at each of the sites: 7.0 (0.0-11) mg/g at Anacapa Island, 5.5 (0.0-12) mg/g at Los Coronados Island, and 0.28 (0.14-0.41) mg/g at San Martin.

5.

DCC eggs collected from various locations in Canada were analyzed for DDE and PCBs (Gilbertson and Reynolds, 1974). The following geometric means were determined for DDE and PCB respectively for each region (mg/g dry weight): British Columbia (N=1), 21.9 and 75.3; Alberta (N=2), 20.9 and 13.2; Saskatchewan (N=1), 22.2 and 4.29; Manitoba (N=2), 46.9 and 8.34; and Lake Nipigon (N=52), 56.8 and 77.5.

6.

Mean DDE concentrations in 90 DCC eggs collected during 1970-1976 from 11 colonies in eastern Canadian coastal waters ranged from 1.49-8.57 mg/g wet weight (Pearce et al, 1979). The highest mean and individual concentrations were generally found in 1972 and 1973, declining markedly by 1976. PCB means ranged from 5.66-19.3 mg/g and dieldrin from 0.07-0.21 mg/g.

7.

Eggs (N=17) from DCC rookeries on Dry Lake and South Waubay Lake, South Dakota, were collected for analysis in the early 1970s and analyzed for organochlorine residues (Greichus et al., 1973). Average DDE and PCB concentrations were 10.38 mg/g weight and 5.9 mg/g, respectively. Heptachlor epoxide, lindane, and dieldrin were found at levels of 0.05, 0.05, and 0.13 mg/g, respectively. Hepatic concentrations of PCBs in nestlings averaged 0.60 mg/g.

8.

One egg per 4-egg clutch was collected from Lake Ontario, Lake Erie, Georgian Bay in Lake Huron, the North Channel of Lake Huron, Lake Superior, Lake Nipigon, and Lake-of-the-Woods in 1970-72, 1975, 1979, 1981, 1983, 1984, 1989, 1990, and 1995 and analyzed for organochlorine pesticides, PCBs, dioxins, and dibenzofurans (Ryckman et al., 1998).  Mean DDE concentrations were greatest at Georgian Bay compared to other sites in 1972-73 at 18.56 g/g wet weight but declined at all sites until the means ranged from 2.26-2.83 g/g in 1995.  Mean dieldren was highest at Lake Huron in 1972-73 at 0.47 g/g, but declined at all sites until the means ranged from 0.05-0.09 g/g in 1995.  Mean mirex was highest at Lake Ontario in 1981 at 0.87 g/g, but declined at all sites until the means ranged from 0.03-0.29 g/g in 1995.  Mean photomirex was highest at Lake Ontario in 1984 at 0.28 g/g, but declined at all sites until the means ranged from 0.01-0.03 g/g in 1995. Mean oxychlordane was highest at Lake Superior in 1984 at 0.13 g/g, but declined at all sites until the means ranged from 0.03-0.04 g/g in 1995.  Mean heptachlor epoxide was 0.26 and 0.18 g/g at Georgian Bay and Lake Nipigon, respectively in 1972-73 and 0.15 g/g at Lake Superior in 1984, but <0.1 g/g at all other sites in all collection periods.  Mean HCB was 0.18 g/g at Georgian Bay in 1970-72 and <0.1 g/g at all other sites in all collection periods. Mean concentrations of trans-nonachlor, and cis-nonachlor were <0.1 g/g at all sites in all collection periods.  Mean total PCBs were greatest at Lake Erie in each collection period, with a peak in 1979 at 35.5 g/g, but declined at all sites until the means ranged from 2.52-15.46 g/g in 1995.  For eggs collected between 1989-91, mean concentrations of TCDD, 1,2,3,7,8-PnCDD, 1,2,3,6,7,8-HxCDD, 1,2,3,4,6,7,8-HpCDD, OCDD, 1,2,3,4,7,8-HxCDD, and 1,2,3,7,8,9-HxCDD ranged from 9-20, 14-27, 11-25, 8-21, 4-22, 1-3, and 3-8 pg/g, respectively.  For eggs collected between 1989-91, mean concentrations of 2,3,7,8-TCDF, 2,3,4,7,8-PCDF, 1,2,3,4,7,8/1,2,3,4,6,7-HxCDF, 1,2,3,6,7,8-HxCDF, and 2,3,4,6,7,8-HxCDF ranged from ND-2, 8-21, 2-7, 1-4, and 1-4 ng/g.

9.

The mean (standard deviation) concentration of DDE in 11 eggs collected in 1971 from Fatpot Island, Bay of Fundy, Maine, was 29.4 (8.5) mg/g wet weight (Zitko et al., 1972; Zitko and Choi, 1972; Zitko and Hutzinger, 1972) Four eggs collected at the same time from Hospital Island, Passamaquoddy Bay in New Brunswick, Canada had a mean DDE concentration of 8.63 (1.25) mg/g. PCB (Aroclor 1254) residues in eggs from these sites were 43.5 (2.6) and 17.2 (0.79) mg/g, respectively. Trace quantities of hexachlorobenzene, DDT, heptachlor epoxide, and dieldrin were present in most samples. Chlorinated dibenzodioxins and dibenzofurans were not detected.

10.

Eggs (9-10/year, 1 egg/nest) were collected in early May 1971 through 1975 from the DCC colony on Whitehorse Island, Bay of Fundy, for determination of chlorinated hydrocarbons in yolk (Zitko, 1976). Annual arithmetic means (standard deviation) of DDE residues from 1971-1975 were 9.70 (0.86), 6.72 (3.59), 2.89 (1.54), 1.92 (0.45), and 2.01 (5.21) mg/g wet weight, respectively. Mean DDD and DDT concentrations were <0.2 mg/g during the sampling period. PCB concentrations were 14.3 (0.86), 9.06 (3.42), 5.57 (2.46), 5.25 (1.90), and 5.23 (3.67) in samples from 1971-1975, respectively. Dieldrin was present in the 1972 samples at a concentration of 0.297 mg/g but generally lower (<0.20 mg/g) thereafter. HCB and mirex were found but at very low levels (generally <0.1 mg/g).

11.

Fresh and intact eggs (N=10), and dented and cracked eggs (N=8), were collected in 1972 from 5 colonies in the Lake Huron area and analyzed for contaminants (Weseloh et al., 1983). The overall mean (standard deviation) for DDE concentration was 14.5 (6.2) mg/g wet weight, with colony means ranging from 5.12-16.4 mg/g. Mean concentrations of parent DDT and DDD were 0.22 (0.20) and 0.17 (0.15) mg/g, respectively. Mean PCB concentration was 23.8 (9.6) mg/g, ranging from 10.3- 25.6 mg/g in the 5 colonies. Mean dieldrin concentration was 0.33 (0.33) mg/g, and heptachlorobenzene and heptachlor epoxide were found, and averaged mean levels < 0.05 mg/g.

12.

DCC eggs collected in 1973 from the Bay of Fundy and Passamaquoddy Bay contained pentachlorophenol at a concentration of 0.36 ng/g wet weight (Zitko et al., 1974).

13.

From 1973-1976, DCC eggs (N=4) were collected from Ugaiusyak Island, Gulf of Alaska (N=4) and from Shaiak Island, Bristol Bay, Alaska (N=3) (Ohlendorf et al., 1982). Concentrations of DDE and PCB were <1 mg/g wet weight in all samples. In eggs from Ugaiusyak Island, heptachlor epoxide, oxychlordane, and HCB were detected at concentrations <1 mg/g. In eggs from Shaiak Island, DDD, dieldrin, heptachlor epoxide, oxychlordane, cis-nonachlor and HCBs were found at <1 mg/g.

14.

Eggs collected from 1977-1980 in rookeries around Green Bay, Wisconsin and Lake Michigan were analyzed for organochlorine contaminants (Heinz et al., 1985). Mean contaminant concentrations ranged from 0.40 to 5.3 mg/g wet weight DDE and from 2.0 to 16.5 mg/g PCB. TDE, heptachlor epoxide, oxychlordane, cis-chlordane, trans-nonachlor, cis-nonachlor, endrin, toxaphene, HCB, mirex, PCS, and PBB were detected at concentrations <1 mg/g.

15.

Organochlorine contaminants were quantified in eggs (N=10) collected in 1979 from the Oregon coast (Henny et al., 1982). Geometric mean (standard deviation) concentrations of DDE and PCBs were 1.6 (0.77-5.2) and 1.3 (0.45-10) mg/g fresh wet weight, respectively. Dieldrin was detected in 2 eggs at 0.09 and 0.19 mg/g, oxychlordane in 2 eggs at 0.12 and 0.16 mg/g; and cis-nonachlor in 1 egg at 0.09 mg/g.

16.

Twenty eggs were collected in both 1981 and 1992, from Lakes Ontario and Erie by the Canadian Wildlife Service (Haffner et al., 1997). Concentrations were recorded in mg/g wet weight.

1981 Lake Erie; PCB congener #52 31, #97 5.89, #101 132, #118 1,066, #153 2,216, #105 165, #138 2,445, #180 1,756, #203 280, #77 0.08, #126 2.60, #169 0.45, Aroclor1254-1260 33,044.

1992 Lake Erie; PCB congener #52 15, #97 1.67, #101 61, #118 601, #153 1,804, #105 106, #138 1,758, #180 1,626, #203 246, #77 0.04, #126 2.08, #169 0.39, Aroclor1254-1260 23,754.

1981 Lake Ontario; PCB congener #52 24, #97 3.09, #101 76, #118 647, #153 1,070, #105 108, #138 994, #180 691, #203 136, #77 0.15, #126 2.14, #169 0.16, Aroclor1254-1260 13,573.

1992 Lake Ontario; PCB congener #52 12, #97 0.04, #101 35, #118 653, #153 528, #105 104, #138 981, #180 913, #203 146, #77 0.09, #126 2.54, #169 0.36, Aroclor1254-1260 13,381.

17.

Eggs collected in 1984 from Protection Island National Wildlife Refuge (N=11) and Colville Island (N=36), Washington, were analyzed for organochlorine contaminants and heavy metals (Henny et al., 1989). Geometric mean concentrations of DDE were 0.59 mg/g wet weight at Protection Island National Wildlife Refuge and 0.58 mg/g at Colville. The highest concentrations detected were 3.2 mg/g at Colville Island and 1.7 mg/g at Protection Island. Mean PCB levels were 2.19 mg/g at Colville Island and 1.37 mg/g at Protection Island, with highest values of 25 and 12 mg/g at each site, respectively.

18.

In 1984, DCC eggs (N=127) were collected from 12 sites in southern Alberta, Canada for analysis of organochlorine contaminants (Somers et al., 1993). Major contaminants were DDE and PCBs. The overall geometric mean DDE concentration was 3.90 mg/g wet weight, with means from the 12 sites ranging from 2.59-6.16 mg/g. The overall mean PCB concentration was 2.22 mg/g with the 12 sites ranging from 1.16-5.58 mg/g. The mean dieldrin concentration, based on analysis of eggs from 3 sites, was 0.068 mg/g. Cis-chlordane was not detected in any of the eggs, and DDD and parent DDT were detected in only 7 eggs. Other chlorinated chemicals found at concentrations <0.01 mg/g included HCB, BHC, oxychlordane, heptachlor epoxide, mirex and endrin.

19.

Between 1986-1988, DCC eggs were collected from 11 colonies in 5 locations around the Great Lakes and a distant reference site outside the lake region (Tillitt et al., 1992). Samples were analyzed for total PCBs and for TCDD-equivalents via an in vitro H4IIE rat hepatoma bioassay. Reproductive success was also monitored at these sites. Mean total PCB concentrations ranged from 0.1 to 14.8 mg/g wet weight from the sites in the Great Lakes compared to 0.08 mg/g in eggs from the reference location. Concentrations of H4IIE bioassay-derived TCDD-equivalents ranged from 85 to 344 pg/g in eggs from the Great Lakes sample regions compared to 35 pg/g from the reference eggs.

20.

DDE, PCB, TEQs and other organochlorine contaminants were determined in DCC eggs collected in 1988 from the upper areas of the Great Lakes for correlations with toxicological endpoints (Yamashita et al., 1993). PCB concentrations in the DCC eggs ranged from 3600 to 7300 pg/g wet weight and DDE levels ranged from 2200-6300 pg/g. Other organochlorines were present at concentrations <60 pg/g.

21.

In 1989, DCC eggs and chicks were collected from 8 sites in the Great Lake region and assayed for total PCBs, and TCDD-equivalents using the in vitro H4IIE rat hepatoma bioassay (Jones et al., 1994). The TCDD-equivalents ranged from 141.7 to 382.3 pg/g wet weight in eggs and from 17.9 to 398.9 pg/g in chicks from the 7 sites. Concentrations of both PCBs and TCDD-equivalents decreased immediately upon hatching of the chicks. Rates of accumulation of both contaminants in growing chicks were directly correlated with concentrations in forage fish consumed by the chicks.

22.

In 1989, one DCC egg was collected from each of 1000 nests on Spider Island, near Green Bay, Wisconsin (Williams et al., 1995). Nine pools of three eggs each were randomly selected for contaminant analysis. Mean (range) concentration of total PCBs was 15.5 (9.71-38.4) mg/g wet weight. Mean concentrations were determined for non-ortho-substituted PCB congeners 77 (2.03 ng/g), 81 (2.23 ng/g), 126 (6.12 ng/g), 169 (1.27 ng/g), and mono-ortho-substituted congeners 105 (224 ng/g), 118 (595 ng/g), 138 (924 ng/g) and 153 with co-eluting congener 132 (1530 ng/g). Mean TEQs and TCDD-EQ were determined to be 150 and 350 pg/g, respectively. PCB congeners contributed <50% of the total TCDD-EQs in these samples.

23.

In 1990 and 1991, DCC eggs were collected from one highly contaminated colony (Pigeon Island, Lake Ontario, N=4), three moderately contaminated colonies (two near the Straight of Georgia, British Columbia--near Crofton, N=6, and on Christy Island, N=12,--and one from an ecological reserve on the southern tip of Vancouver Island, N=15), and one reference colony (Lost Mountain Lake, Saskatchewan, N=12) (Henshel et al., 1997).  Mean TCDD concentrations were 5.6 pg/g wet weight at the reference site, 20.8-33.4 pg/g at intermediate sites, and 37.3 at Lake Ontario.  Concentrations of individiual PCB congeners, respectively, were 83, 41-76, and 342 pg/g PCB-77; 520, 256-784, and 3731 pg/g PCB-126; 89, 49-104, and 430 pg/g PCB-169, 133,000, 26,000-62,000, and 173,000 pg/g PCB-188; 18,300, 26,000-62,000, and 173,000 pg/g PCB-105.  TEQs values are reported for several methods of calculation; mean values as calculated by Safe were 241.44 pg/g at the reference site, 253.37-611.88 pg/g at intermediate sites, and 1276.58 pg/g at Lake Ontario.

24.

About 1000 DCC eggs were collected from Big Sister Island, Green Bay, Lake Michigan and combined to form one 41,293 gram sample (Meadows et al., 1996). Total PCB concentration for the sample was 5849 ng/g. Individual PCB congeners analyzed included non-ortho-substituted: 81 (883 pg/g), 77 (570 pg/g), 126 (3667 pg/g), and mono-ortho-substituted: 105 (301 ng/g), 114 (19 ng/g), 118 (704 ng/g), 123 (7.4 ng/g), 156 (59 ng/g), 157 (20 ng/g), 167 (49 ng/g), and 189 (7.8 ng/g). Concentrations of dieldrin and DDE were quantified as .0257 and 1.155 mg/g, respectively. Concentrations of HCB, a-BHC, b-BHC, oxychlordane, heptachlor epoxide, trans-nonachlor, cis-chlordane, o,p=-DDD, endrin, cis-nonachlor, DDD, DDT , and mirex were <0.1 mg/g.

25.

As part of a reproductive study, 75 DCC eggs were collected for contaminant analysis from nests on Cat Island, Green Bay, Wisconsin in 1994 and 1995 (Custer et al., 1999).  Mean concentrations for both years combined were 13.6 g/g wet weight total PCBs, 3.9 g/g DDE, 0.25 g/g dieldrin, 0.08 g/g heptachlor epoxide, 0.5 g/g oxychlordane, 0.04 g/g cis-nonachlor, 0.02 g/g mirex, and 0.01 g/g HCB.  trans-Nonachlor, cis-chlordane, endrin, toxaphene, DDD, and DDT were detected in less than half the samples.  HCH isomers, trans-chlordane, o,p-DDE, o,p-DDD, and o,p-DDD were not detected in any samples.

26.

In 1994 and 1995, DCC pipping embryos were collected from Wisconsin (Spider Island, Hat Island, and Cat Island), Minnesota (Marsh Lake), and South Dakota (Piyas Lake) (Custer et al., 2001).  Geometric mean (range) total PCB concentrations (N=10/colony) at Marsh Lake & Piyas Lake, Spider Island, Hat Island, and Cat Island were, respectively: 0.9 (0.1-4.6), 9.6 (5.2-20.1), 10.0 (7.1-15.0), and 13.4 (9.0-22.8) mg/g wet weight. For all four sites, mean concentrations of cis-nonachlor, oxychlordane, HCB, mirex, and congeners 114, 128, 156, 157, 158, 167, and 189 were all below 1 mg/g. Concentrations of congener 126 were nine- to ten-fold higher at Spider, Hat, and Cat Islands than at the reference sites, Marsh and Piyas Lakes. Wisconsin sites had significantly higher concentrations of all organochlorines except mirex and HCB.

 

Geometric mean dieldrin concentrations (N=5/colony/year) in 1994 were 0.066, 0.391, 0.212, and 0.140 mg/g at Piyas Lake, Spider Island, Hat Island, and Cat Island, respectively and in 1995 were 0.029, 0.095, 0.114, and 0.088 mg/g at Marsh Lake, Spider Island, Hat Island, and Cat Island, respectively.  Geometric mean heptachlor epoxide concentrations (N=5/colony/year) in 1994 were 0.023, 0.113, 0.086, and 0.048 mg/g at Piyas Lake, Spider Island, Hat Island, and Cat Island, respectively and in 1995 were ND, 0.064, 0.042, and 0.044 mg/g at Marsh Lake, Spider Island, Hat Island, and Cat Island, respectively. Geometric mean DDE concentrations (N=5/colony/year) in 1994 were 1.15, 3.63, 4.14, and 1.94 mg/g at Piyas Lake, Spider Island, Hat Island, and Cat Island, respectively and in 1995 were 0.67, 1.74, 2.42, and 3.59 mg/g at Marsh Lake, Spider Island, Hat Island, and Cat Island, respectively.

Geometric mean congener 77 concentrations (N=5/colony/year) in 1994 were 0.0001, 0.0004, 0.0004, and 0.0003 mg/g at Piyas Lake, Spider Island, Hat Island, and Cat Island, respectively and in 1995 were ND, 0.0001, ND, and 0.0002 mg/g at Marsh Lake, Spider Island, Hat Island, and Cat Island, respectively. Geometric mean congener 105 concentrations (N=5/colony/year) in 1994 were 0.014, 0.102, 0.102, and 0.092 mg/g at Piyas Lake, Spider Island, Hat Island, and Cat Island, respectively and in 1995 were 0.011, 0.132, 0.176, and 0.373 mg/g at Marsh Lake, Spider Island, Hat Island, and Cat Island, respectively. Geometric mean congener 169 concentrations (N=5/colony/year) in 1994 were ND, 0.0002, 0.0001, and 0.0001 mg/g at Piyas Lake, Spider Island, Hat Island, and Cat Island, respectively and in 1995 were ND, 0.0001, 0.0001, and 0.0001 mg/g at Marsh Lake, Spider Island, Hat Island, and Cat Island, respectively. Geometric mean Van den Berg TEQs in 1994 were 13, 188, 128, 106 pg/g at Piyas Lake, Spider Island, Hat Island, and Cat Island, respectively and in 1995 were 6, 98, 120, and 227 pg/g at Marsh Lake, Spider Island, Hat Island, and Cat Island, respectively.

27.

Fresh eggs (N=5) were collected in 1995 from a colony of DCC on Cat Island, Green Bay, Wisconsin that was contaminated with PCBs (Custer et al., 1997). Samples consisting of egg contents (excluding shell and chorioallantoic membrane) and sibling embryos (head, yolk sac, liver, fecal sac and remaining carcass) were analyzed for organochlorine contaminants including PCB congeners. A total of 20 organochlorine compounds including 13 PCB congeners were detected in all eggs and sibling embryos. In eggs and embryos, DDE concentrations were 2.22 and 2.17 mg/g wet weight, respectively, and total PCBs were 12.9 and 14.0 mg/g, respectively. Dieldrin, concentrations were 0.147 and 0.157 mg/g in the eggs and embryos, respectively. Oxychlordane, cis-nonachlor, and heptachlor epoxide were detected at values <0.05 mg/g. The most common PCB congeners were 118/106 and 138.

28.

Freshly laid DCC eggs were collected from Lake Huron and Lake Superior, Michigan, sites in May 1998 (Kannan et al., 2001). Mean (range) concentrations (N=3) from Little Charity Island, Lake Huron, were (in pg/g wet weight), respectively: 1,650,000 (1,250,000-2,370,000) total PCBs, 1200 (620-2400) total PCNs, 62 (25-97) 2,3,7,8-PCDDs, and 48 (28-76) 2,3,7,8-PCDFs. Mean (range) concentrations (N=3) from Scarecrow Island, Lake Huron, were (in pg/g), respectively: 1,420,000 (1,220,000-1,680,000) total PCBs, 1100 (520-1900) total PCNs, 16 (7.4-26) 2,3,7,8-PCDDs, and 37 (22-57) 2,3,7,8-PCDFs. Mean (range) concentrations (N=3) from Taquamenon, Lake Superior, were (in pg/g), respectively: 1,790,000 (1,130,000-2,960,000) total PCBs, 1100 (380-2000) total PCNs, 26 (18-37) 2,3,7,8-PCDDs, and 27 (20-37) 2,3,7,8-PCDFs. No significant differences between sites were found. Low concentrations of 2,3,7,8-substituted PCDDs and PCDFs were reported.

Mean TCDD equivalents, totaling 55 pg/g, for Little Charity Island were (in pg/g): 33 PCBs, 1.1 PCNs, 13 PCDDs, and 7.8 PCDFs. Mean TCDD equivalents, totaling 35 pg/g, for Scarecrow Island were (in pg/g): 25 PCBs, 1 PCNs, 3.2 PCDDs, and 6 PCDFs. Mean TCDD equivalents, totaling 38, for Taquamenon were (in pg/g): 28 PCBs, 0.89 PCNs, 6.3 PCDDs, and 3.1 PCDFs. PCNs only contributed 2-3% of the total TEQs while PCBs contributed 60-73%.

II.

Cholinesterase-Inhibiting Pesticides

 

No direct exposure data available.

III.

Trace Elements, Metals, and Metalloids

A.

Concentrations in Adults, Juveniles, and Nestlings

1.

Tissues from DCCs (N=10) were collected in the early 1970s from rookeries on Dry Lake and South Waybay Lake, South Dakota (Greichus et al., 1973). Mercury concentrations in adult body, muscle, kidney, and liver were 0.64, 0.78, 1.51, and 7.98 mg/g wet weight. Hepatic concentrations of Hg in nestlings averaged 0.28 mg/g.

2.

Adult DCC were collected in the early 1970s from 3 sites on the Cheyenne river system in South Dakota (N=6), and controls (N=3) were collected from Lewis and Clark Lake and the Missouri River, South Dakota (Hesse et al., 1975). Mean (SE) Hg concentrations in pectoris muscle, liver, and kidney from the Cheyenne River birds were 2.28 (0.74), 30.9 (15), and 7.49 mg/g wet weight, respectively, compared to 0.94 (0.29), 7.61 (3.66), and 3.02 (1.04) mg/g in birds from the control site.

3.

Concentrations of Hg in breast muscle and liver were determined in one adult DCC collected from the Savannah area of Georgia in 1978 and one collected from the same area in 1980 (Odom, 1981). Mercury concentrations in the muscle and liver were 1.70 and 13.69 mg/g wet weight, respectively, in the bird collected in 1978, and 0.64 and 2.13 mg/g in the bird collected in 1980.

4.

Concentrations of Hg were determined in tissues from adult DCC (N=3) collected from the Quoddy area of New Brunswick (Braune, 1987). One bird was field collected during the period of 1978-1984 and two were received from the New Brunswick Museum as obtained in 1978-1979. Mean tissue Hg concentrations in muscle, liver, kidney and brain were 0.606, 7.048, 5.345, and 0.360 mg/g wet weight, respectively.

5.

Concentrations of several elements were determined in liver of three adult DCCs found dead in 1984 near Williamson Rocks, Washington (Henny et al., 1989). Concentrations in the birds ranged from of 5.7-12.0 mg/g wet weight Hg, 3.4 to 4.2 mg/g Se, 3.6-5.2 mg/g Cu, 180-309 mg/g Fe, and 20.8-27.1 mg/g Zn.

6.

Concentrations of several elements were determined in nine adult DCC collected in 1986 from the Mexicali Valley in northeastern Baja, California (Mora and Anderson, 1995). Mean (range) Se liver concentrations were 5.1 (2.9-7.3) mg/g wet weight which were significantly higher than in tissues of 4 other species of birds collected at the same time. Levels of Zn, Cd, Cu, Cr, and B were similar in DCC and the other 4 species and considered to be well below thresholds for biological effects in birds.

7.

Adult DCC were collected during the 1988 breeding season from Heron and Manawagonish Islands, New Brunswick, and juveniles about 6 weeks of age were collected from Manawagonish Island and from Ile au Pommes, Quebec (Elliott et al., 1992). Tissues were analyzed for toxic metals (Cd, Hg, and Pb) plus 18 other trace elements. Mean (range) concentrations of Hg in adult liver samples from the 2 sites were 9.2 (3.1-29) and 21 (1.0-82) mg/g dry weight while values in the juvenile birds were lower, 1.68 (1.2-2.20) and 1.18 (0.70-2.10) mg/g. In kidneys, Hg values in adults from the 2 sites were 10.5 (2.45-42.6) and 12.9 (3.61-27.7) mg/g compared to 1.09 (0.83-1.55) and 0.77 (0.50-1.50) mg/g in the juveniles. Mean Pb levels in tissues of adult and juveniles were generally <0.5 mg/g except in bone of adults from one site where the mean was 0.84 (0.12-2.87) mg/g. Selenium levels varied greatly but were in the broad range normally expected. Histological examination of liver and kidney failed to reveal any indications of tissue damage associated with elevated levels of heavy metals. Levels of the essential trace elements were in close agreement with previously reported literature values.

8.

From 1993 to 1994, double-crested cormorant nestlings were collected near a Hg mine in Clear Lake, California (Wolfe and Norman, 1998).  Mean (range) Hg concentrations in tissues were 0.63 (0.54-0.72) mg/g wet weight in brain, and 2.42 (1.91-2.94) mg/g in liver. 

In 1993, at Quercus Point, mean (standard deviation) Hg concentrations in tissues of five young double-crested cormorants (in mg/g wet weight) were 0.72 (0.15) in brain, 2.94 (1.07) in liver, and 2.95 (0.31) in feathers.

In 1994, at Quercus Point, mean (standard deviation) Hg concentrations in tissues of 10 young double-crested cormorants (in mg/g) were 0.54 (0.09) in brain, 1.91 (0.39) in liver, and 4.05 (1.32) in feathers.

Mercury concentrations were not correlated to distance from the Hg mine.

9.

In 1994, adult DCC feathers were collected at Agassiz NWR in Minnesota (Burger and Gochfeld, 1996). Mean heavy metal concentrations in adult feathers were: 1930310 ng/g dry weight Pb, 957167 ng/g Cd, 4840878 ng/g Hg, 1510135 ng/g Se, 790111 ng/g Cr, and 40,1006764 ng/g Mn.

10.

In 1995, 20 DCC hatchlings, ages 0 11 days, were collected from Dor Lake, Saskatchewan, Canada and raised at the Animal Care Unit, University of Saskatchewan (Kuiken et al., 1999).  These birds were euthenized at ages 5 to 27 weeks.  In 1992, ten four-week-old DCC with normal bills were collected from each of the following places, and euthanized: Churchill Lake, Saskatchewan, Canada; Pigeon Island, eastern Lake Ontario, Canada; Little Gull Island, upper Green Bay, Lake Michigan, USA.  Pb concentration in the liver of a captive cormorant with a normal bill (n = 1) was 0.21mg/g dry weight; Cd was 1.12 mg/g, Hg was 1.10 mg/g, and Se was 5.06 mg/g.  Pb concentration in the kidenys of captive cormorants with crossed-bills were <0.08 mg/g, Cd was 2.44 0.37 mg/g, Hg was 0.93 0.26 mg/g, and Se was 4.23 0.53 mg/g.  In kidneys of free-living cormorants collected at Churchill Lake, Lake Ontario, and Lake Michigan, respectively: Pb concentrations were <0.04, 0.07, and <0.04 mg/g; Cd concentrations were <0.16, 0.64, and 0.82 mg/g; Hg concentrations were 0.27, 1.26, and 0.78 mg/g; and Se concentrations were 3.4, 15.3, and 8.2 mg/g (each number represents an average from 10 birds). 

11.

Sick or injured birds were collected from southern Florida between 1994-97, and analyzed for Hg and Se (Sepulveda et al. 1998).  Mean Hg concentration in liver, kidney, and brain was 48, 12, and 1.5 g/g wet weight, respectively in adults and 12, 4.8, and 1.6 g/g in juveniles. Mean Se concentration in liver, kidney, and brain was 19, 9.9, and 1.2 g/g in adults and 4.1, 3.5, and 0.45 g/g in juveniles.

12.

In 1995, blood, liver, muscle, and feathers were collected from DCC nestlings at Caballo and Elephant Butte reservoirs in New Mexico (Caldwell et al., 1999).   The number of samples ranged from 3-18.  Blood was collected twice, at 7-10 days after hatching and again 10-12 days later.  Mean (range) blood Hg concentrations for Caballo and Elephant Butte, respectively, were 0.36 (0.20-0.70) and 0.36 (0.22-0.72) g/g wet weight at the first collection, and 0.39 (0.39-0.40) and 0.34 (0.22-0.50) g/g at the second collection.  Concentrations of Hg in other tissues for the two reservoirs were 0.40 (0.34-0.48) and 0.40 (0.30-0.51) g/g in liver, 0.18 (0.16-0.21) and 0.17 (0.12-0.23) g/g in muscle, 3.54 (2.20-4.60) and 2.42 (1.40-5.30) g/g in primary feather, 4.89 (2.40-10.0) and 2.06 (1.40-3.20) g/g in secondary feather, and 4.01 (2.40-7.60) and 2.34 (1.50-5.0) g/g in tail feather.  Concentrations of Hg in feathers were not strongly correlated with concentrations in other tissues. 

B.

Concentrations in Eggs and Embryos

1.

Mean Hg concentration in DCC eggs (N=5) collected about 1970 from rookeries on Dry Lake and South Waubay Lake in South Dakota was 0.29 mg/g wet weight (Greichus et al., 1973). Hepatic concentrations of Hg in nestlings averaged 0.28 mg/g.

2.

Mean Hg concentrations in 90 DCC eggs collected during 1970-1976 from 11 colonies in eastern Canadian coastal waters ranged from 0.21-0.50 mg/g wet weight (Pearce et al, 1979).

3.

Mean (SD, where N>1) Hg values in DCC eggs (N=18) collected in 1972 from 3 sites in the North Channel of Lake Huron were 0.32, 0.34 (0.12), and 0.38 (0.11) mg/g wet weight, and 0.83 (0.09) and 0.53 (0.04) mg/g from 2 sites from the Georgian Bay area (Weseloh et al., 1983). The overall mean concentration of Hg in eggs from the 5 sites was 0.46 (0.20) mg/g.

4.

Mean Hg concentrations in DCC eggs (N=19) collected from 1977 to 1980 from sites around Green Bay and Lake Michigan were <0.32 mg/g wet weight (Heinz et al., 1985).

5.

DCC eggs were collected in 1984 from 2 nesting sites in northwest Washington (Henny et al., 1989). Mean Hg and Se concentrations were 0.26 and 0.28 mg/g wet weight in eggs (N=11) from Protection Island, respectively, and 0.27 and 0.31 mg/g in eggs (N=12) from Colville Island. Both elements were found in all eggs. Maximum concentrations at each site were 0.67 and 0.44 mg/g Hg and 0.41 and 0.47 mg/g Se.

6.

In 1994, DCC eggs were collected at Agassiz NWR in Minnesota (Burger and Gochfeld 1996). The mean heavy metal concentrations in the eggs were: 12839 ng/g dry weight Pb, 39046 ng/g Cd, 1610128 ng/g Hg, 196087 ng/g Se, 60026 ng/g Cr, and 2990128 ng/g Mn.

7.

In 1995, eggs collected from DCCs nests at Caballo (n=36) and Elephant Butte (n=36) reservoirs in New Mexico contained mean (range) Hg concentrations of  0.30 (0.13-0.46) and 0.23 (0.13-0.46) mg/g wet weight, respectively (Caldwell et al.,  1999).  

VI.

Petroleum

1.

Petroleum hydrocarbons in DCC (N=20) collected from the Houston Ship Channel in late 1982 and early 1983 consisted of aliphatic as well as aromatic hydrocarbons (King et al., 1987). Concentrations in the carcass (after removal of skin, bills, feet and gastrointestinal tract) remained relatively constant or declined slightly during the 3-4 month over wintering period. The mean (range) concentration of n-C15 was 1.52 (0.56-3.00) mg/g wet weight in the first samples but declined to 0.69 (0.12-1.70) mg/g in the spring samples. Levels of n-C17 and pristane were high in the November samples, 1.22 and 4.44 mg/g, respectively, but declined markedly by spring. Mean levels of other petroleum were generally <0.5 mg/g in November.

V.

Other

1.

DCC were collected in mined (N=6 composite samples) and unmined (N=4 composite samples) areas from both northern and central Florida (Myers et al., 1989). Mean (range) Ra-226 concentrations in bone in mined areas, Bq/kg fresh weight, were 4.6 (4.4-4.8) in the north and 4.4 in central sites. In unmined areas, bone concentrations were 3.0 (2.6-3.3) in the north and 3.7 (3.0-4.4) in the central area. Concentrations in muscle of other duck species were 1-2 orders of magnitude lower than in bone but muscle levels in DCC were not determined.

2.

Examination of 497 DCC nests on 3 islands in the Gulf of Maine during 1987 and 1988 revealed the presence of plastic debris in 188 or 37% of the nests (Podolsky and Kress, 1989). The debris, consisting primarily of sections of lobster trap line, plastic bags and plastic fishing line, was considered potentially hazardous to adults by entanglement during nest restoration.

3.

DCC livers had the following concentrations (in ng/g) of perfluorooctane sulfonate: 59, 76, 145, 170, and 333 from St. Martinville, Louisiana; and 10, 52, 100, 152, and 212 from Naples, Florida (Minnesota Mining and Manufacturing Company, 2000).

Double-Crested Cormorant Contaminant Response Data

I.

Organochlorine Contaminants

A.

Eggshell Thinning and Reproduction

1.

Eggshell weight and thickness in DCC were found to be highly correlated with concentrations of DDE and PCBs (Anderson et al., 1969). Population status of 11 colonies of cormorants was related to contaminant residues and eggshell thickness.

2.

Reproductive success of DCCs from southern California colonies relative to DDE concentration in eggs was compared (Gress et al., 1973). On the west islet of Anacapa Island, 76 nesting attempts were found in 1969 in the 2 colonies, but none produced young. Crushed and discarded shells were strewn about the colony sites. On the South Los Coronados Island, 32 active nests produced only 1 young bird in 1969. Crushed shells and fragments were also scattered around the nests. On San Martin Island, the cormorant population numbered approximately 5000 birds in 1969 and the colony did not have any apparent reproduction problems. Mean concentration of DDE was 754 and 574 mg/g yolk lipid (or about 32 and 24 mg/g wet weight) from the Anacapa and Los Coronados colonies compared to 41.4 mg/g yolk lipid in eggs from the San Martin colony. Shell thickness of intact and crushed eggs from the Anacapa colony was decreased by 10.5% and 41.5%, respectively, compared to thickness of pre-1946 eggs. In the Los Coronados colony, shell thickness in intact and crushed eggs was decreased 30.4% and 41.2%.

3.

DDE levels of 10 mg/g wet weight in eggs collected during 1970-1976 from 11 colonies in eastern Canadian coastal waters were associated with a 20% reduction of shell thickness (Pearce et al, 1979).

4.

DCC colonies at Lake Huron in 1972 were small and nests showed high rates of egg breakage and loss (95%), and nearly total reproductive failure (Weseloh et al., 1983). Eggshell thickness was 23.9% lower than normal and was associated with high concentrations of DDE (14.5 mg/g wet weight) and PCBs (23.8 mg/g). Concentrations of other chlorinated hydrocarbons and Hg were <1 mg/g. Colony size declined further in 1973, although reproductive success improved somewhat.

5.

DCC eggs (N=10) were collected in 1979 along the Oregon coast for residue analysis and the measurement of eggshell thickness (Henny et al, 1982). The limited eggshell thickness data provided evidence that thickness in 1979 was similar to, or slightly thicker than, eggs collected on this coast in the 1950s. The mean DDE concentration and range was 1.6 (0.77-5.2) mg/g wet weight. The authors concluded that residue levels in eggs posed no threat to the welfare to DCC.

6.

In 1984, reproduction (young produced) was markedly reduced in northwestern Washington, and associated with small clutch size and late egg laying (Henny et al., 1989). Mean DDE concentrations in eggs from 2 sites in the area were 0.58 and 0.59 mg/g wet weight which were considered to be below levels associated with reproduction problems. Eggshell thickness, when compared to pre-1947 values was 5.6% thinner at 1 site, and 5.1% thicker at a second location. After 1984, populations shifted to other sites in the study area, and by 1988, nesting populations were the highest recorded. Decreases in 1984 were considered to be related to disturbance in the nesting areas by humans.

7.

Mean shell thickness of 14 DCC eggs collected "opportunistically" in 1984 from Goose Island in Grays Harbor on the Washington coast was 5% greater than that measured in pre-1947 eggs, although the change was not statistically significant (Speich et al., 1992).

8.

In Alberta, Canada, east of the Canadian Rockies, eggshell thickness was not correlated with DDE concentrations in eggs (Somers et al., 1993).

9.

The potency of PCB-containing extracts from DCC eggs collected from Great Lakes colonies in 1986-87 were bioassayed by their ability to induce cytochrome P-450IA1-associated EROD activity in H4IIE rat hepatoma cells using TCDD as a standard (Tillitt et al, 1991). TCDD-EQs for DCC egg extract from the Great Lakes study areas ranged from 94.0-344.1 pg/g. Even though the biological significance of these values have not been established and may not be predictive of toxicological effects, highest values were found in areas with the most severely affected reproduction effects.

10.

TCDD-EQs of PCB-containing extracts from DCC eggs were highly correlated with hatching success of eggs collected from 11 Great Lakes colonies in 1986-1987, whereas simple PCB residue concentrations were poorly correlated with successful hatching from these same colonies (Tillitt et al., 1992). TCDD-EQs were in the range of 35-344 pg/g. PCB concentrations were 0.05 to 14.8 mg/g wet weight and egg mortality ranged from 8-39%. Egg mortality was more highly correlated with TCDD-EQs than with PCB concentrations.

11.

One egg per 4-egg clutch was collected from Lake Ontario, Lake Erie, Georgian Bay in Lake Huron, the North Channel of Lake Huron, Lake Superior, Lake Nipigon, and Lake-of-the-Woods in 1989 and 1995 and the eggshell was examined for thinning (Ryckman et al., 1998).  Eggshell thinning in 1989 ranged from 3.6-9.5 %, and in 1995 from 0-3.9 %.  There were no significant difference among sites in 1995, and thickness in 1995 was 2.2% greater than in museum specimens from 1947.  No correlations were found between eggshell thickness and DDE.

12.

In 1994 and 1995, 423 DCC nests were monitored for reproductive success on Cat Island, Green Bay, Wisconsin (Custer et al., 1999).  For both years combined, 32% of eggs laid did not hatch.   The mean number of chicks raised to 12 days was 2.2 in 1994 and 2.0 in 1995.  Egg success (% eggs hatched in a clutch) was positively correlated with eggshell thickness (mean=0.410 mm) and negatively correlated with DDE and dieldrin concentrations.  Eggshell thickness was negatively correlated with DDE and dieldrin concentrations.  Concentrations of DDE, but not dieldrin or PCBs, were determined to be a significant factor in hatching success, as determined by logistic regression. 

13.

In 1994 and 1995, DCC pipping embryos were collected from Wisconsin (Spider Island, Hat Island, and Cat Island), Minnesota (Marsh Lake), and South Dakota (Piyas Lake) (Custer et al., 2001). Mean eggshell thickness was less at Spider Island (0.395 mm; N=74) and Hat Island (0.384 mm; N=53) than at Cat Island (0.412 mm; N=271) or the reference locations (0.415 mm; N=51; Priyas and Marsh Lakes).  Mean thickness was 3.5 to 10.7% less than pre-1947 values.

14.

Egg yolks were injected prior to incubation with 1.3, 5.4, 10.7, or 11.7 ng/g TCDD or 70, 175, 349, or 698 ng/g PCB 126 (Powell et al., 1998).  Embryo mortality was 41.9-44.7% in controls, 62.7% at 1.3 ng/g TCDD, 84.9% at 11.7 ng/g TCDD, 61.2% at 70 ng/g PCB 126, and 94.1% at 689 ng/g PCB 126.  Embryo LD50 was 4.0 ng/g  for TCDD and 177 ng/g for PCB 126.

B.

Biochemical and Morphological Responses

1.

Contaminant effects other than impaired reproduction and population dynamics in DCC have been reported, as populations have shown recovery trends (Fox et al., 1991a, 1991b). The initial 1991 paper reviewed reproductive outcomes for 6 species, including the DCC, and recommended the use of cormorants in biomonitoring programs to measure exposure and effects of polyhalogenated aromatic hydrocarbons and other contaminants in aquatic food chains in the Great Lakes. In the second study, conducted from 1979 to 1987, a greater incidence of congenital malformations was observed in the Great Lakes when compared to a reference area. In the Great Lakes sites, 31,168 DCC chicks were examined during 147 visits to 42 colonies and 70 of the chicks had crossed bills or bills where the mandibles differed in length. In the reference areas, only 2 of 20,962 chicks during 82 visits to 35 colonies had bill defects. Other studies in Lake Michigan suggested that chemicals such as PCBs that induce arylhydrocarbon hydroxylase are responsible for the observed effects.

2.

Chicks at Lake Ontario, Lake Erie, Georgian Bay in Lake Huron, the North Channel of Lake Huron, Lake Superior, Lake Nipigon, and Lake-of-the-Woods were surveyed for bill deformities between 1979-87 and 1988-1996 (Ryckman et al., 1998).   Prevalence of bill deformities ranged from none observed at the reference sites at Lake Nipigon and Lake-of-the-Woods to 2.8/10,000 chicks at the Great Lakes sites.  Prevalence of bill deformities did not differ significantly among Great Lakes sites, and only Georgian Bay showed a decrease in the prevalence of bill deformities between the two time periods.

3.

DDE, PCB, TEQ and other organochlorine contaminants were determined in DCC eggs collected in 1988 from the upper areas of the Great Lakes for correlations with toxicological endpoints (Yamashita et al., 1993). The relationship between rates of reproductive abnormalities (dead but normal, dead abnormal or infertile eggs) and contaminant concentrations revealed higher rates of live-deformity (hard tissue malformations such as crossed-bill and club-foot) in DDC eggs with greater TEQ. It was also concluded that non-ortho-coplanar PCBs contributed much more toxicity than PCDDs and PCDFs.

4.

The effects of various chlorinated contaminants and TCDD-EQs on liver microsomal EROD activity were determined in DCC eggs collected from 5 areas across Canada (Sanderson et al., 1994). A brain malformation was found in 1 of 7 chicks from the Crofton colony, and a deformed liver was seen in 1 of 11 chicks from the Lake Ontario colony. Hepatic EROD activity was directly related to TCDD-EQs, and yolk weight and wing length were inversely related to TCDD-EQs.

5.

Dose-responses curves were estimated for hepatic microsomal EROD induction by TCDD in 4 avian species (including DCC hatchlings) to compare their relative sensitivity (Sanderson and Bellward, 1995). DCC were 1-2 orders of magnitude less sensitive than chicken, possibly due to lower affinity of TCDD to the arylhydrocarbon receptor.

6.

In 1990 and 1991, DCC eggs were collected from one highly contaminated colony (Pigeon Island, Lake Ontario), three moderately contaminated colonies (two near the Straight of Georgia, British Columbia--near Crofton and on Christy Island--and one from an ecological reserve on the southern tip of Vancouver Island), and one reference colony (Lost Mountain Lake, Saskatchewan) (Henshel et al., 1997).  Eggs were incubated until hatching, sacrificed and examined for brain asymmetry.  Birds from Lake Ontario, where TEQ and PCB values are greatest, had the highest frequency of brain asymmetry, with 8 of 10 asymmetric in at least one measurement, and 6 asymmetric in three or four measurements.  Chicks from the reference colony exhibited asymmetry in one measurement only in just two of the brains.  Frequency of asymmetry at other sites was intermediate.  TCDD and TEQ explained more of the variability in asymmetry measurements than concentrations of individual PCB congeners.

7.

In 1994 and 1995, DCC pipping embryos and 10-day old chicks were collected from Wisconsin (Spider Island, Hat Island, and Cat Island), Minnesota (Marsh Lake), and South Dakota (Piyas Lake) (Custer et al., 2001). Pipping embryo liver EROD activity varied by year, site, and interaction. In 1994, EROD activities were significantly lower at the reference location (Piyas Lake) and Spider Island, significantly higher at Cat Island, and Hat Island was not different from the other locations. In 1995, Hat Island embryo livers had significantly higher EROD activity than the other locations. Spider Island and Cat Island EROD activities were significantly higher than Marsh Lake (reference site). Ten-day old chick liver EROD activities were significantly different between years but not between locations.

8.

In 1995, 20 DCC hatchlings, ages 0 11 days, were collected from Dor Lake, Saskatchewan, Canada and raised at the Animal Care Unit, University of Saskatchewan (Kuiken et al., 1999).  These birds were euthenized at ages 5 to 27 weeks.  In 1992, ten four-week-old DCC with normal bills were collected from each of the following places, and euthanized: Churchill Lake, Saskatchewan, Canada; Pigeon Island, eastern Lake Ontario, Canada; Little Gull Island, upper Green Bay, Lake Michigan, USA.  Bill deformites were not attributable to organochlorine contaminants in the DCC.

9.

EROD activity was measured in hepatic microsomes and primary hepatocyte cultures in DCC eggs collected in 1993 and 1994 from Humboldt Bay and San Francisco Bay, California, and a reference site in coastal Oregon (Davis et al., 1997). Median microsomal EROD activities were four- to eightfold higher in the California colonies, indicating exposure to TCDD-like compounds. EROD response in cultured hepatocytes showed a large degree of variation between individuals and populations. Most individuals displayed a consistent dose-response profile, though some individuals showed no increase in activity with increasing dose of inducer.

10.

DCC eggs collected from a colony in Manitoba, Canada, in 1994 were injected with either PCB 126, TCDD, or an extract derived from field-collected DCC eggs (Powell et al., 1997). An LD50 of 158 mg/kg egg was determined for PCB 126. Mortality of chicks injected with the highest dose of TCDD, 4.0 mg/kg egg, was significantly higher than mortality of controls, though data was insufficient to determine an LD50. There was no difference in mortality between controls and those inject with the DCC extract. There was no significant difference in the incidence of structural abnormalities and no consistent changes in organ weights for any of the treatment groups.

11.

In 1994 and 1995, 423 DCC nests were monitored for reproductive success on Cat Island, Green Bay, Wisconsin (Custer et al., 1999).  Of 1570 eggs laid, 6 (0.4%) had deformed embryos, though PCB concentrations did not differ in eggs collected from nests containing deformed embryos and egg collected from nests where all eggs hatched and no embryos were deformed.  EROD activity, measured at a mean of 57.0 pmol/min/mg in 210 pipping embryos, was positively correlated with PCB concentrations in sample eggs. 

12.

Eggs yolks were injected prior to incubation with either 1.3, 5.4, 10.7, or 11.7 ng/g TCDD or 70, 175, 349, or 698 ng/g PCB 126 (Powell et al., 1998).  Bursa mass was 0.030 g in controls, and ranged from 0.023- 0.029 g in TCDD-injected eggs, and from 0.027-0.030 g in PCB-injected eggs.  Spleen mass was 0.077 g in controls, and ranged from 0.045-0.074 g in TCDD-injected eggs, and from 0.050-0.087 g in PCB-injected eggs.  Liver mass was 0.72 g in controls, and ranged from 0.72-0.74 g in TCDD-injected eggs, and from 0.75- 0.80 g in PCB-injected eggs.  EROD activity was 92.0 pmol/min/mg in controls, and ranged from 462 -707 pmol/min/mg in TCDD-injected eggs, and from 673-886 pmol/min/mg in PCB-injected eggs.  No effect on hatchling weights, hatchling sex ratio, gonadal histopathology, or spleen histopathology was noted in any treatment.

II.

Cholinesterase-Inhibiting Pesticides

 

No response data available

III.

Trace Elements, Metals and Metalloids

1.

Twenty-two cormorants, approximately age 8 weeks, were dosed for 8 weeks with none, 3.5 or 0.5 mg methyl HgCl/kg diet/day (Samuelson and Szabo 1999).  The eyes were analyzed for Hg content and by light and electron microscopy.  Light microscopy in the 3.5 group showed vacuoles in the nerve fiber layer and a thin and disrupted outer plexiform layer.  Electron microscopy showed swollen photoreceptor outer segments with fragmentation of disc lamellae.

IV.

Petroleum

 

No response data available  

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