USGS



BIOLOGICAL AND ECOTOXICOLOGICAL CHARACTERISTICS OF TERRESTRIAL VERTEBRATE SPECIES RESIDING IN ESTUARIES

American Alligator American Alligator photo by USFWS
 Photo by United States Fish & Wildlife Service


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Biological Characteristics   

Species

Alligator mississippiensis is the largest reptile species in North America; they are distinguished from crocodiles by their long, broad snout (Conant and Collins, 1998; Behler and King, 1979).  As adults, they range from 6 feet to 19 feet 2 inches long, young are 8 to 10 inches at hatching.  The average weight of an adult male is 350 pounds; females are generally smaller than males (Barkley, 1998).  Adults are dark all over, almost black, and young are dark with bold yellow markings (Conant and Collins, 1998).

Status in Estuaries

They live in fresh and brackish marshes, ponds, lakes, rivers, swamps, and bayous (Conant and Collins, 1998; Behler and King, 1979). From November to March, alligators will often enter their dens and go into a state similar to hibernation (Barkley, 1998).  The female builds a nest out of soil and vegetation, approximately 4 to 7 feet in diameter, and 1 to 3 feet high (Barkley, 1998; Conant and Collins, 1998).  Eggs usually number 25-60 per mound, are 3 inches long, and have hard white shells (Behler and King, 1979).  The female guards the nest, assists the hatchlings out of the mound, and carries them to water in her mouth (Barkley, 1998).  The oldest captive animal was 56 years.

Abundance and Range

American alligators are found from North Carolina to southeast Texas, along the Atlantic and Gulf coasts, and in large rivers  (Conant and Collins, 1998).  The population is recovering after being extirpated from many areas due to hunting and human encroachment, and their status was revised from endangered to threatened by the federal government in 1987.  More than one million wild alligators may currently reside in Florida. Current threats include continuing human encroachment and environmental contaminants. 

Site Fidelity

Young stay together in groups with their mother for 1-3 years, not moving far from their hatching site (Barkley, 1998; Behler and King, 1979). Extremely territorial during nesting season.

Ease of Census

Difficult.

Feeding Habits

Alligators have a diverse diet, eating fish, mammals, birds, turtles, snakes, frogs, and invertebrates (Behler and King, 1979).  They are primarily nocturnal when the weather is hot. 


American Alligator Contaminant Exposure Data

I.

Organochlorine Contaminants

A.

Concentrations in Adults

1.

In 1985, alligator tail muscle was collected from 32 alligators at eight Florida lakes: Iamonia, Newnans, Orange, Rodman, George, Apopka, Hancock, and Trafford (31 male, 1 female; mean length 3.3 m) (Delany et al., 1988) .  Concentrations of chlorinated hydrocarbons in muscle (μg/g wet weight), in the order of lakes listed above, were: DDE 0.06, ND for all others; DDD 0.12, ND, ND, ND, ND, 0.03, 0.02, 0.02; DDT 0.10, ND, 0.42, ND, ND, 0.16, ND, ND; Dieldrin 0.08, 0.05, 0.03, 0.02, 0.12, 0.10, 0.04, 0.02; heptachlor epoxide 0.14, 0.05, 0.11, 0.09, 0.20, 0.13, 0.08, 0.04; lindane 0.04, ND, ND, ND, 0.02, 0.03, ND, 0.01; PCBs 1.5, 0.1, 1.4, 0.7, 1.5, 2.1, 1.1, 0.2. 

            2.

Fifteen adult females were collected from Lakes Apopka, Griffin, and Lochloosa during June 2001 and 2002 (Raushenberger et al. 2004).  Total organochlorine pesticide concentrations ranged from <0.8 in blood to >44,000 ng/g ww in adipose tissue. 

B.

Concentrations in Juveniles

1.

Blood serum was collected from juvenile alligators on Lake Woodruff National Wildlife Refuge, Lake Apopka, and Orange Lake, Florida in September 1995 (Guillette et al., 1999b). 

Serum from Lake Woodruff (N=14 male and 6 female) contained the following mean concentrations (ng/ml) of contaminants: alpha-chlordane ND; dieldrin 0.24 male, 0.31 female; endrin 0.90 male, 0.86 female; gamma-chlordane ND male, trace female; mirex trace; oxychlordane trace male, ND female; trans-nonachlor trace male, 0.41 female; o,p-DDT 0.53 male, 0.63 female; p,p-DDT trace; o,p-DDE trace; p,p-DDE 0.92 male, 1.28 female; p,p-DDD trace. 

Serum from Lake Apopka (N=6 male and 7 female) contained the following mean concentrations (ng/ml) of contaminants: alpha-chlordane trace; dieldrin 1.68 male, 2.87 female; endrin 1.43 male, 1.19 female; gamma-chlordane trace; mirex 0.28 male, 0.34 female; oxychlordane 0.39 male, 0.63 female; trans-nonachlor 0.39 male, 0.91 female; o,p-DDT 0.45 male, 0.70 female; p,p-DDT trace; o,p-DDE trace male, 0.62 female; p,p-DDE 7.35 male, 17.98 female; p,p-DDD ND male, 0.58 female. 

Serum from Orange Lake (N=11 male and 7 female) contained the following concentrations (ng/ml) of contaminants; alpha-chlordane ND; dieldrin 0.75 male, 0.39 female; endrin 0.87 male, 0.71 female; gamma-chlordane trace; mirex trace; oxychlordane ND; trans-nonachlor ND; o,p-DDT 0.69 male, 0.49 female; p,p-DDT trace; o,p-DDE trace; p,p-DDE 0.92 male, 0.77 female; p,p-DDD trace male, ND female. 

Other contaminants were not different among sites, mean concentrations were as follows (N=52): aldrin (N=46) 0.34; β-HCH ND; δ- HCH ND; HCB (N=44) 0.25; heptachlor epoxide (N=3) 0.42; heptachlor (N=27) trace.  Congeners of PCBs were quantified, the highest concentration was 0.42 ng/ml of PCB-66 in a female from Lake Woodruff; only congeners 66, 74, 105, 146, 153, 156, 170, and 180 were found in greater than trace concentrations at any site.

            2.

Eggs were collected from reference sites and sites downstream from a  coal-burning electric power plant between june and august 1997, 1999, and 2000 (Roe et al. 2004).  Eggs were artificially incubated and hatchlings and remaining chorioallantoic membranes were collected for trace element analysis.  Selenium concentrations were generally higher from sites near the power plant.  Selenium in chorioallantoic membranes ranged from 5.0-27.2 ug/g dw.  Hatchling selenium concentrations ranged from 1.41-7.75 ug/g dw.

C.

Concentrations in Eggs

1.

In 1984, two eggs were collected from nests in Lakes Okeechobee (N=7), Griffin (N=6), and Apopka (N=3), and in 1985, one egg was collected from nests in Griffin (N=21) and Apopka (N=23) (Heinz et al., 1991) .  In 1984, p,p-DDT, heptachlor epoxide, oxychlordane, and endrin were not detected.  Mean concentrations (μg/g, wet weight) in 1984, for Okeechobee, Griffin, and Apopka, respectively, were: toxaphene ND, 0.06, 0.09; dieldrin ND, 0.06, 0.24; p,p-DDE 0.87, 0.45, 5.8; p,p-DDD ND, ND, 0.82; cis-chlordane ND, ND, 0.09; trans-nonachlor ND, 0.05, 0.11; cis-nonachlor ND, ND, 0.07; PCBs ND, 0.08, 0.17.  In 1985, HCB, HCH, heptachlor epoxide, PCBs, o,p-DDD, o,p-DDT, endrin, cis-nonachlor, mirex, and dicofol (plus metabolites) were not detected.  Mean concentrations (μg/g) in 1985, for Griffin and Apopka, respectively, were: toxaphene 1.1, 2.4; dieldrin 0.05, 0.11; p,p-DDE 0.58, 3.5; p,p-DDD 0.0007, 0.37; p,p-DDT ND, 0.02; o,p-DDE 0.05, 0.007; trans-chlordane 0.02, 0.006; cis-chlordane 0.03, 0.06; trans-nonachlor 0.09, 0.15; oxychlordane 0.03, 0.03.  Hatching success in Apopka in 1985 was 19 5.42% and at Griffin it was 46.4 7.97%.  Mean eggshell thickness index was 2.91 for Apopka and 2.90 for Griffin, and was not correlated with DDE residues. 

2.

Eggs were collected from Bear Island (N=20) (reference site) and Yawkey Wildlife Center on Winyah Bay (N=21), South Carolina (Cobb et al., 1997). Mean total PCB concentrations in chorioallantoic membranes were 711 ng/g lipid weight from Bear Island (N=15) and 1671 ng/g from Yawkey.  Mean total PCBs in the egg were 386 ng/g from Bear Island (N=19) and 3763 ng/g from Yawkey. 

3.

Eggs collected from Bear Island wildlife management area of the Ashepoo, Combahee, Edisto river basin, South Carolina were incubated in the lab until hatching, chorioallantoic membranes (CAMs) were collected (N=13), and neonates were euthanized after 3 weeks (Bargar et al., 1999).  Maximum DDE concentrations were 7542 ng/g lipid weight in fat, 2632 ng/g in yolk, and 1489 ng/g in CAM. Concentrations of PCB congeners ranged from ND to approximately 250 ng/g in CAM and yolk, and from ND to approximately 750 ng/g in fat. 

            4.

Eggs from 15 clutches were collected from Lakes Apopka, Griffin, and Lochloosa during June 2001 and 2002 (Raushenberger et al. 2004).  Eggs collected from Lake Apopka contained the highest total organochlorine pesticide concentrations (15,108 ng/g ww), with DDE and toxaphene being the main constituents.  Eggs from Lake Griffin and Lake Lochloosa contained 393 and 124 ng/g ww organochlorine pesticides, respectively. 

            5.

American alligator eggs were collected early in incubation from reference sites and sites downstream from a  coal-burning electric power plant between june and august 1997, 1999, and 2000 (Roe et al. 2004).  Selenium concentrations were generally higher in samples collected near the power plant.  Selenium concentrations in egg contents ranged from 2.21-7.64 ug/g dw.

II.

Cholinesterase-Inhibiting Pesticides

 

No direct exposure data available

III.

Trace Elements, Metals, and Metalloids

1.

Breeding female alligators were collected between 1977 and 1982 at the Rockafeller Refuge, Grand Chenier Louisiana (Lance et al., 1983).  Blood was collected from the heart and analyzed for Ca, Mg, Zn, Cu, Fe, and Se.  Wild alligator data was combined with captive alligators that were being fed either nutria or fish.  Sample size was 2 to 15 alligators per month, per feeding category.  Mean Ca concentrations ranged from 8.51 mM/L (May, nutria-fed) to 2.74 mM/L (July, wild); Mg from 1.73 mM/L (May, nutria-fed) to 1.06 mM/L (July, nutria-fed); Zn from 1.84 ug/mL (April, fish-fed) to 0.46 ug/mL (July, nutria-fed); Cu from 0.70 ug/mL (June and July, fish-fed) to 0.52 ug/mL (July , nutria-fed); Fe from 2.35 ug/mL (April, wild) to 0.32 ug/mL (July, fish-fed); Se from 0.27 ug/mL (June and July, fish-fed) to 0.15 ug/mL (June, wild).  Concentrations in males did not vary among months.

2.

In 1984, two eggs were collected from nests in Lakes Okeechobee (N=7), Griffin (N=6), and Apopka (N=3), and in 1985, one egg was collected from nests in Griffin (N=21) and Apopka (N=23) (Heinz et al., 1991) .  Mean concentrations (μg/g wet weight) in eggs in 1984, for Okeechobee, Griffin, and Apopka, respectively, were: Al 1.5, 2.0, 1.3; Cr 0.09, 0.08, 0.09; Cu 0.32, 0.78, 0.52; Fe 13, 13, 11; Pb 0.14, 0.22, ND; Mn 0.14, 0.15, 0.14; Ni 0.07, 0.05, 0.09; Se 0.31, 0.37, 0.30; Zn 6.7, 7.6, 5.6.  Arsenic, Be, Cd, Hg, Mo, Tl, V were not detected after corrections for moisture loss. 

3.

In 1985, alligator tail muscle was collected from 32 alligators at eight Florida lakes: Iamonia, Newnans, Orange, Rodman, George, Apopka, Hancock, and Trafford (31 male, 1 female, mean length 3.3 m) (Delany et al., 1988) .  Metal concentrations (μg/g wet weight), in the order of lakes listed above, were: Cu 0.49, 0.41, 0.39, 0.28, 6.03, 0.40, 0.34, 1.02; Zn 25.25, 36.00, 27.88, 19.00, 22.17, 14.20, 25.50, 19.75; Fe 8.74, 15.38, 17.71, 7.42, 22.76, 4.56, 8.45, 10.26; Cr 0.05, 0.05, 0.05, 0.05, 0.06, 0.03, 0.05, 0.11; Hg 0.61, 0.27, 0.37, 0.51, 0.04, 0.11, 0.10, 0.43; Pb 0.08, 0.12, 0.04, 0.07, 0.09, 0.07, 0.10, 0.09; Cd 0.01, 0.02, 0.06, 0.02, 0.03, 0.03, 0.01, 0.06.

4.

In 1989 tail muscle was collected from wild alligators in canals and other nuisance alligators in Florida (Hord et al. 1990) .  Samples collected in February from Water Conservation Areas 2 and 3 (N=8) contained 1.6 ug/g Hg; those collected in June (N=10) contained 2.92 ug/g Hg; samples from the Ft. Lauderdale area (N=19) contained 0.74 ug/g Hg; samples from alligator meat processing plants (N=58) contained 0.39 ug/g Hg

5.

Blood was collected from alligators at Rockefeller Wildlife Refuge in Louisiana (Lance et al., 1995).  Mean concentrations and ranges of plasma Zn were 0.44 (0.18-0.70) ug/mL in males; 0.50 (0.32-0.90) ug/mL in females not breeding; and 1.83 (1.28-3.48) ug/mL in breeding females. 

6.

In 1992, 24 alligators from Water Conservation Area 3 in the Florida Everglades and from Aluchua, Brevard, and Collier counties outside the Everglades were collected, as well as six captive (control) alligators (Heaton et al., 1997) .  The size ranged from 185.5 cm to 303.5 cm.  Alligators from the Everglades and 6 of 12 wild-caught outside the Everglades exceeded state and federal allowable levels of Hg for safe human consumption.  Mean Hg concentrations (ug/g wet weight) for Everglades, non-Everglades, and farm raised alligators, respectively, were: liver 39.99, 2.52, 0.10; kidneys 25.85, 1.58, 0.09; spleen 3.70, 0.45, 0.09; tail muscle 2.61, 0.33, 0.10; leg muscle 2.70, 0.28, 0.11; heart 2.31, 0.30, 0.11; brain 1.37, 0.16, 0.08; spinal cord 1.34, 0.97, 0.16; ovaries 0.70, 1.30, 0.12; oviducts 1.19, 1.20, 0.20; testes 1.17, 0.19, 0.18; tail scales 1.03, 0.34, 0.08; lungs 0.98, 0.27, 0.10; leg scales 0.82, 0.35, 0.08; bile 0.17, 0.23, 0.10. 

7.

In 1994, alligators (mostly under 2 years old) were collected from the Everglades in south Florida (N=18), the northwest Florida peninsula (N=21), the Okefenokee Swamp in south Georgia (N=9), and the U.S. Department of Energys Savannah River site (SRS) in South Carolina (N=49) (Jagoe et al., 1998) .  Concentrations of Hg in muscle and scutes did not differ between SRS and Everglades; central Florida and Okefenokee samples had significantly less Hg.  Concentrations in the liver and kidney were lowest from Okefenokee, and highest from the Everglades.  Mean Hg (μg/g, dry weight) from Everglades, central Florida, Okefenokee, and SRS, respectively, were: muscle 5.57, 1.85, 0.80, 4.83; liver 41.03, 14.61, 4.30, 14.90; kidney 36.42, 12.59, 4.82, ND; scute 5.83, 0.52, 0.29, 5.14; claw ND, 2.69, 1.67, ND.  Mean Hg in other tissues (N=8-11) were: whole blood from SRS, 2.19; bone from Okefenokee, 0.16; fat from Okefenokee, 0.19; spleen from Okefenokee, 0.63; brain from Okefenokee, 0.46. 

8.

In 1994 and 1995, alligators were sampled from Water Conservation Area 3A (6 males, 4 females) and Holiday Park (4 males, 4 females) in Broward County, Florida, and from Par Pond at the Savannah River (25 males, 15 females, 9 unknown), near Aiken, South Carolina (Yanochko et al., 1997) .  Those from Florida were approximately 5 to 6.5 years old and those from South Carolina 10 years old.  Concentrations of Hg (μg/g dry weight) for Holiday Park, WCA-3A, and Par Pond, respectively, were: kidney 38.46 (N=7), 35.00 (N=10), not determined; tail scute 5.12 (N=7), 6.33 (N=10), 4.58 (N=39); liver 39.75 (N=8), 42.15 (N=10), 17.73 (N=17); muscle 5.43 (N=8), 5.68 (N=10), 4.08 (N=21). 

9.

In July 1997, seven dead and two dying 1-year old alligators were collected from an alligator farm (Camus et al., 1998) .  The alligators had little fat on their abdomen and fascial side of their tails, little stomach contents, and fragments of Pb bullets in their stomachs (found in 5 of 7).  One individual had clear mucoid exudates in its lungs.  Compared to controls, the epithelial cell nuclei were enlarged and had marginated chromatin.  Blood Pb ranged from 0.07-2.80 mg/L, and 0.03-0.04 mg/L in controls.  In three samples, Pb was 1.14, 1.20, and 1.30 μg/g in kidney, and 1.50, 1.70, and 1.20 mg/L in blood Pb.  Kidney Pb concentrations in 3 dead alligators were 0.40, 2.70, and 5.60 μg/g.  Liver Pb concentrations were 0.46 and 0.37, and controls were 0.03 and 0.06 μg/g.  Muscle Pb concentrations were all below 0.1 μg/g.  In kidneys of 3 individuals, As was below 0.1 μg/g. 

10.

Tail muscle (N=41) was collected from alligators in southern Louisiana in 1998 (Elsey et al., 1999) .  Mean (range) Hg was 0.131 (0.047-0.386) μg/g.  Samples from the southwest were significantly higher than those from the southeast (N=14 and 27, respectively).  There was not a significant difference between males and females pooled from all sites. 

11.

Yearling alligators were collected from Lake Apopka, Orange Lake, and Lake Woodruff, Florida (Burger et al., 2000).  Mean concentrations of metals are given below, in μg/g wet weight. 

Lake Apopka (N=20):  Fat: 19.6 Pb, 73.8 Cd, 256 Se, 113 Cr, 369 Mn, 35.1 As, 165 Sn, 10.0 Hg; Liver: 9.86 Pb, 127 Cd, 429 Se, 133 Cr, 1380 Mn, 41.0 As, 231 Sn, 108 Hg; Abdominal muscle: 4.67 Pb, 33.3 Cd, 141 Se, 69.8 Cr, 209 Mn, 11.2 As, 51.0 Sn, 16.6 Hg; Skin: 10.9 Pb, 88.0 Cd, 143 Se, 144 Cr, 221 Mn, 31.6 As, 58.0 Sn, 11.4 Hg; Proximal tail muscle: 26.7 Pb, 78.0 Cd, 187 Se, 252 Cr, 802 Mn, 24.1 As, 72.6 Sn, 57.0 Hg; Tail tip: 218 Pb, 104 Cd, 132 Se, 225 Cr, 613 Mn, 40.4 As, 330 Sn, 21.1 Hg.

Orange Lake and Lake Woodruff (N=30):  Fat: 23.0 Pb, 48.6 Cd, 102 Se, 72.7 Cr, 295 Mn, 8.89 As, 114 Sn, 68.1 Hg; Liver: 36.2 Pb, 122 Cd, 742 Se, 70.9 Cr, 1140 Mn, 31.8 As, 160 Sn, 543 Hg; Abdominal muscle: 20.5 Pb, 30.6 Cd, 108 Se, 54.7 Cr, 345 Mn, 11.2 As, 65.9 Sn, 105 Hg; Skin: 23.7 Pb, 38.7 Cd, 126 Se, 96.5 Cr, 456 Mn, 14.0 As, 101 Sn, 75.8 Hg; Proximal tail muscle: 47.1 Pb, 55.9 Cd, 138 Se, 230 Cr, 663 Mn, 11.8 As, 111 Sn, 64.9 Hg; Tail tip: 34.7 Pb, 97.1 Cd, 175 Se, 174 Cr, 1090 Mn, 12.2 As, 211 Sn, 68.7 Hg.

Alligators with regenerated tails (N=3) had more than 3 times the amount of Mn in their tails than in normal tails (N=27).  Females (63.0 μg/g) had more Hg in fat than males (34.7 μg/g), and less Sn in their tails (153 μg/g versus 396 μg/g).

IV.

Petroleum

 

No residue data available

V.

Other

1.

Hatchling alligators (N=12) were sampled in 1986 from the U.S. Department of Energys Savannah River Plant, in the Pond B reservoir, in South Carolina (Brisbin, 1986).  The average pCi radiocesium/g wet weight was 13.2. 

American Alligator Contaminant Response Data

I.

Organochlorine Contaminants

1.

In 1992, eggs were collected from 25 nests on Lake Apopka (whole clutches), Florida, and 25 nests on Lake Woodruff (2 viable eggs per nest and all dead eggs), Florida, and incubated at 31.5C to produce a 1:1 sex ratio (Guillette et al., 1994) .  At 6 months, subjects were injected with luteinizing hormone (10 IU, twice), and then sacrificed.  Mean clutch size for Lake Apopka was 47.8 young, with 13.9 hatching (8 clutches produced no viable eggs, and 5 produced over 75% viable eggs).  Mortality of hatchlings to 10 days was 41% for Apopka, and <1% for Woodruff.  Mortality of juveniles from 10 days to 6 months was 9 of 25 for Apopka, and 2 of 25 for Woodruff.  Females from Apopka had higher estradiol than Woodruff females and all males.  Males from Woodruff had four times higher testosterone than Apopka males and all females.  Testosterone in males from Apopka was not different than either group of females.  With the administration of luteinizing hormone, males from Apopka had the strongest response, producing large amounts of estradiol, and females from Apopka had the weakest response.  Two Apopka individuals with testes did not have a penis, and two with a penislike structure had ovaries.  Ovaries of females from Apopka contained polyovular follicles and polynuclear oocytes, females from Woodruff did not.  Males from Apopka had poorly organized seminiferous tubules in comparison to Woodruff males, and Apopka males had cuboidal epithelium lining the seminiferous tubules and the nuclei in the seminiferous tubules of Apopka males were bar-shaped, unlike Woodruff males.  The authors suggest contamination with an estrogenic xenobiotic is responsible for the observed abnormalities in alligators from Apopka. 

2.

Alligator eggs were collected from Lake Apopka and Lake Woodruff, Florida, incubated, and raised for 6 months, when blood serum was collected (Guillette et al., 1995).  Ovaries from Lake Apopka, in an in vitro test, synthesized significantly less estradiol-17 than those from Lake Woodruff.  Testes from Lake Apopka synthesized significantly more estradiol-17 than those from Lake Woodruff, and the amount was not different from ovaries from Lake Apopka.  The addition of lueteinizing hormone (LH) to the cultures only affected ovaries from Lake Apopka.  In an in vitro test, ovaries produced less testosterone than testes, neither was affected by addition of LH, and amounts did not differ between sites.  The authors suggest that environmental contaminants have modified the gonadal steroidogenesis by reducing gonadotropin releasing hormone, reducing LH, reducing cholesterol, modifying enzymes required for steroidogenesis, and modifying cellular receptor number and function. 

3.

In 1995, juvenile male and female alligators were collected from Lake Apopka (N=14) and Lake Woodruff (N=21), Florida ( Guillette et al., 1997 ).  Initial plasma testosterone concentrations were higher in males from Lake Woodruff, compared to Lake Apoka, which is contaminated with organochlorines; plasma estradiol and corticosterone did not differ between lakes.  Concentrations of testosterone and estradiol did not change in the two hours after capture; corticosteroids increased 29-32 fold in alligators from both lakes.  The authors suggest that the contaminants do not affect juvenile alligator glucocorticoid response if they are exposed in ovo.

4.

Blood serum was collected from juvenile alligators on Lake Apopka, Lake Woodruff National Wildlife Refuge, and Lake Okeechobee, Florida in April and May 1995 (Crain et al., 1998).  There were no differences among lakes for triiodothyronine and estrogen concentration in males or females, testosterone in males, and thyroxine in females.  Mean testosterone concentrations were higher in males from Woodruff compared to the other sites.  Thyroxine concentrations were lower in males from Woodruff than in males from Okeechobee.

Testosterone was positively correlated with body size in males at Okeechobee and Woodruff, but not Apopka.  There was no relationship of body size to estrogen in males.  Estrogen was related to body size in females from Okeechobee and Woodruff, but not Apopka.  Testosterone was positively correlated with body size in females from Woodruff, but not Okeechobee or Apopka.  Triiodothyronine and thyroxine were negatively correlated with size in males and females from Woodruff, and in males from Apopka and Okeechobee, but not in the females from those sites.  Thyroxine was negatively correlated with body size in females from Apopka. 

The authors suggest the differences among lake and between males and females are due to gender-specific effects of endocrine disrupting chemicals.

5.

Juvenile alligators were collected from Lake Apopka, Lake Woodruff National Wildlife Refuge, and Orange Lake, Florida in September 1995 (Guillette et al., 1999b).  Serum testosterone concentrations were significantly lower in male alligators from Lake Apopka and Orange Lake compared to those from Lake Woodruff, and were not significantly different from the females from all sites.  Males from Lake Apopka had significantly shorter phallus tip length than those from Lake Woodruff.  Testosterone concentrations and phallus length were not correlated with concentrations of any specific contaminant.  The authors suggest the effects may be due to embryonic exposure to a mixture of contaminants.

6.

Approximately 250 alligator eggs were collected from Bear Island Wildlife Management, Beaufort County, South Carolina (Matter et al., 1998) .  Eggs were treated with TCDD, o,p-DDE, p,p-DDE, coumestrol, indole-3carbinol, and ethynylestradiol, incubated at male-producing temperatures, and reared to 21 days.  Of the control eggs, 18 out of 20 hatched as males, and 2 as females.  Of the eggs treated with 1-10 μg/g ethynylestradiol, 9 were male and 4 were female.  The TCDD and p,p-DDE treatments also produced significant numbers of females at male producing temperatures.  Females treated with ethynylestradiol and coumestrol had increased medullary vacuoles in size and number, and females treated with TCDD exhibited the opposite.  Testes of males treated with TCDD had masses of abherent cells in the lumen of the seminiferous tubuoles.

7.

Juvenile alligators were collected in Florida in April and May of 1995, at Lake Apopka, Lake Griffin, Lake Monroe, Orange Lake, Lake Okeechobee, Lake Woodruff National Wildlife Refuge, and Lake Jessup (Guillette et al., 1999a) .  Lake Apopka is known to be contaminated with organochlorines.  Males from Apopka, Griffin, and Jessup had significantly lower blood plasma testosterone than males from Woodruff, and males from Monroe, Orange and Okeechobee were intermediate.  Females from Monroe had significantly higher testosterone in plasma than those from Apopka, Griffin, Okeechobee, Woodruff, and Monroe.  Plasma estradiol concentrations in males did not differ among lakes.  Plasma estradiol concentrations in females were significantly higher than Woodruff at Griffin, Apopka, Orange, and Okeechobee, females from Jessup and Monroe were intermediate.  Alligators from all lakes except Apopka showed significant correlation between body size and penis tip length and diameter of the penis cuff.  Testosterone concentrations also explained some of the variation in penis tip length and diameter of the penis cuff.  Penis size of males that were 40-79 cm total length from Apopka and Griffin was significantly smaller, compared to males from all other lakes; larger males from these lakes did not differ from alligators captured in other lakes. 

8.

Juvenile alligators were collected from Lake Woodruff and Lake Apopka, Florida (Pickford et al., 2000).  Alligators from Woodruff were significantly longer (snout-vent length) than those of the same sex from Apopka.  Apopka males were longer than Apopka females.  Phallus length and cuff diameter were smaller in Apopka males than in Woodruff males.  Concentrations of 5α-dihydrotestosterone in blood plasma were not different between males from different lakes, but were higher in females from Apopka than from Woodruff.  The authors suggest that an anti-androgen, such as DDE, may be causing the differences in alligators between the sites.

II.

Cholinesterase-Inhibiting Pesticides

 

No response data available

III.

Trace Elements, Metals, and Metalloids

 

No response data available

IV.

Petroleum

 

No response data available

V.

Other

1.

In 1995, eggs were collected from six nests on Lake Woodruff National Wildlife Refuge, Florida, and six nests on Lake Apopka, Florida, incubated in the laboratory at female temperatures, and raised to 9 months (Crain et al., 1997) .  Gonadal aromatase activity was significantly higher in alligators from Woodruff compared to Apopka.  Concentrations of testosterone were significantly lower in Apopka alligators compared to Woodruff alligators.  In 1995, eggs were collected from seven nests on Lake Woodruff National Wildlife Refuge, Florida, incubated in the laboratory and treated with estradiol, tomoxifen, vinclozolin, atrazine, or 2,4 dichlorophenoxyacetic acid (2,4-D), with 5 eggs in each treatment.  Estradiol and tamoxifen caused 100% sex reversal; no other chemicals caused sex reversals.  Eggs incubated at male producing temperatures hatched into males that may have had increased estrogen when exposed to atrazine, though this was not confirmed.  There were no significant effects of 2,4-D treatment.

References for American Alligator

Barger, T.A., C. Sills-McMurry, R.L. Dickerson, W.E. Rhodes and G.P. Cobb.  1999.  Relative distribution of polychlorinated biphenyls among tissues of neonatal American Alligators (Alligator mississippiensis).  Arch. Environ. Contam. Toxicol. 37:364-368.

Barkley, S.  1998.  The American Alligator.  Arkansas Game and Fish Commission, Little Rock Arkansas.

Behler, J.L. and F.W. King.  1979.  The Audubon Society Field Guide to North American Reptiles and Amphibians.  Knopf, New York.

Brisbin, I.L. Jr.  1986.  Radiocesium levels in a population of American Alligators: a model for the study of environmental contaminants in free-living crocodiles.  Proceedings of the 8th Working Meeting of the Crocodile Specialist Group of the Species Survival Commission of the International Union for Conservation of Nature and Natural Resources, Quito, Ecuador 60-73.

Burger, J., M. Gochfeld, A.A. Rooney, E.F. Orlando, A.R. Woodward, and L.J. Guillette, Jr.  2000.  Metals and metalloids in tissues of American Alligators in three Florida lakes.  Arch. Environ. Contam. Toxicol. 38:501-508.

Camus, C., M.M Mitchell, J.F. Williams, and P.L. Jowett.  1998.  Elevated lead levels in farmed American Alligators Alligator mississippiensis consuming Nutria myocastor coypus meat contaminated by lead bullets.  J. World Aquacult. Soc. 29:370-376.

Cobb, G.P., P.T. Wood, and M. OQuinn.  1997.  Polychlorinated biphenyls in eggs and chorioallantoic membranes of American Alligators (Alligator mississippiensis) from coastal South Carolina.  Environ. Toxicol. Chem. 16:1456-1462. 

Conant, R., and Collins, J.T.  1998.  A Field Guide to Reptiles and Amphibians Eastern and Central North America.  Third Edition, Expanded.  Houghton Mifflin Company, New York.

Crain, D.A., L.J. Guillette, Jr., A.A. Rooney, and D.B. Pickford.  1997.  Alterations in steroidogenesis in alligators (Alligator mississippiensis) exposed naturally and experimentally to environmental contaminants.  Environ. Health Perspect. 105:528-533.

Crain, D.A., L.J. Guillette, Jr., D.B. Pickford, H.F. Percival, and A. Woodward. 1998.  Environ. Toxicol. Chem. 17:446-452.

Delany, M. F., J.U. Bell, and S.F. Sundlof. 1988. Concentrations of contaminants in muscle of the American Alligators in Florida USA. J. Wildl. Dis. 24:62-66.

Elsey, R. M., V.A. Lance, and L. Campbell.  1999.  Mercury levels in alligator meat in south Louisiana.  Bull. Environ. Contam. Toxicol. 63: 598-603.

Guillette, L.J. Jr., T.S. Gross, G.R. Masson, J.M. Matter, H.F. Percival, and A.R. Woodward.  1994.  Developmental abnormalities of the gonad and abnormal sex hormone concentrations in juvenile alligators from contaminated and control lakes in Florida.  Environ. Health Perspect. 102:680-688.

Guillette, L.J. Jr., T.S. Gross, D.A. Gross, A.A. Rooney, and H.F. Percival.  1995.  Gonadal steroidogenesis in vitro from juvenile alligators obtained from contaminated or control lakes.  Environ. Health Perspect. 103(Suppl 4):31-36. 

Guillette,L.J.Jr., D.A. Crain, A.A. Rooney, and A.R.Woodward.  1997.  Effect of acute stress on plasma concentrations of sex and stress hormones in juvenile alligators living in control and contaminated lakes.  J. Herpetol. 31:347-353.

Guillette,L.J.  Jr., A.R. Woodward, D.A. Crain, D.B. Pickford, A.A. Rooney, and H.F. Percival.  1999.  Plasma steroid concentrations and male phallus size in juvenile alligators from seven Florida lakes.  Gen. Comp. Endocrinol.  1999.  116:356-372.

Guillette, L.J. Jr., J.W. Brock, A.A. Rooney, and A.R. Woodward.  1999.  Serum concentrations of various environmental contaminants and their relationship to sex steroid concentrations and phallus size in juvenile American Alligators.  Arch. Environ. Contam. Toxicol. 36:447-455. 

Heaton-Jones, T.G., B.L. Homer, D.L. Heaton-Jones, and S.F. Sundlof. 1997.  Mercury distribution in American Alligators (Alligator mississippiensis) in Florida.  J. Zoo Wildl. Med. 28:62-70.

Heinz, G. H., H. F. Percival, and M. L. Jennings. 1991. Contaminants in American Alligator eggs from Lake Apopka Lake Griffin Lake Okeechobee Florida USA.  Environ. Monitor. Assess.16: 277-286.

Hord L.J., M. Jennings, and A. Brunell. 1990. Mercury contamination of Florida alligators.  Proceedings of the 10th Working Meeting of the Crocodile Specialist Group of the Species Survival Commission of IUCN.  Gainesville, Florida, USA, 229-240.

Jagoe, C.H., B. Arnold-Hill, G.M. Yanochko, P.V. Winger, and I.L. Brisbin.  1998.  Mercury in alligators (Alligator mississippiensis) in the southeastern United States.  Sci. Total Environ. 213:255-262.

Lance, V., T. Joanen, and L. McNease. 1983. Selenium, vitamin E, and trace elements in the plasma of wild and farm-reared alligators during the reproductive cycle.  Can. J. Zoo. 61:1744-1751.

Matter, J.M., C.S. McMurry, A.B. Anthony, and R.L. Dickerson.  1998.  Development and implementation of endocrine biomarkers of exposure and effects in American Alligators (Alligator mississippiensis).  Chemosphere 37:1905-1914.

Pickford, D.B., L.J. Guillette, Jr., D.A. Crain, A.A. Rooney, and A.R. Woodward.  2000.  Plasma dihydrotestosterone concentrations and phallus size in juvenile American Alligators (A. mississippiensis) from contaminated and reference populations.  J. Herpetol. 34:233-239. 

Raushenberger, R.H., M.S. Sepulveda, J.J. Wiebe, N.J. Szabo, and T.S. Gross.  2004.  Predicting maternal body burdens of organochlorine pesticides from eggs and evidence of maternal transfer in Alligator mississippiensis.  Environ. Toxicol. Chem. 23:2906-2915.

Roe, J.H., W.A. Hopkins, J.A. Baionno, B.P. Staub, C.L. Rowe, and B.P. Jackson.  2004.  Maternal transfer of selenium in Alligator mississippiensis nesting downstream from a coal-burning power plant.  Environ. Toxicol. Chem. 23:1969-1972.

Yanochko, G. M., Jagoe, C. H., and Brisbin, I. L. Jr.  1997.  Tissue mercury concentrations in alligators (Alligator mississippiensis) from the Florida everglades and the Savannah River site, South Carolina.  Arch. Environ. Contam. Toxicol. 32: 323-328.

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