USGS



BIOLOGICAL AND ECOTOXICOLOGICAL CHARACTERISTICS OF TERRESTRIAL VERTEBRATE SPECIES RESIDING IN ESTUARIES

California Sea Lion Sea Lion Photo by David Kelly, USGS
Photo by David Kelly, USGS


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Biological Characteristics 

Species

Adult male California sea lions (Zalophus californianus) are around 200 to 250 cm in length and can weigh 200 to 300 kg, Females measure 150 to 200 cm and weigh 50 to 100 kg (Peterson and Bartholomew, 1967). Adult males are distinctive in having a sagittal crest on the skull and a much thicker neck than females (Odell, 1981). The sea lion’s snout is rounded and their pelage is short and coarse (Reidman, 1990). The pelage of adult males is generally brown, varying in shades from dark to light, while that of females and young males are tan (Odell, 1981). Newborn pups are dark brown from birth up to 6 months when they start molting to the tan colored fur of adults. Sea lions have small external ears that are flaps of skin supported by cartilage just behind the eye. Their bodies are insulated by both a layer of fatty tissue called blubber and by thick “waterproof” hair (Reijnders et al., 1993). Three subspecies of the California sea lion are recognized: Z.c.califorianus, Z.c.wollebaeki, and Z.c.japonicus (Reijnders et al., 1993).

Status in Estuarine and Coastal Areas

At sea, sea lions are found in pelagic and near shore waters to surf zone while on land they rest and breed in groups of various sizes and are often found in large rookeries containing thousands of animals (Reidman, 1989). Sea lions sometimes travel up rivers and bays (Reidman, 1989). Although males are known to migrate away from breeding areas along the California coast as far away as Washington and British Columbia after breeding season, little is known concerning whether females and young migrate (Odell, 1981). Females gestate for about 11 months and give birth to a single pup around June. Females then come into estrus about two weeks after parturition (Peterson and Bartholomew, 1967). Pups are precocial with their eyes open at birth, capable of highly coordinated motor activities 10 to 15 minutes after delivery, and able to walk within 30 minutes (Peterson and Bartholomew, 1967). The life span of a sea lion is estimated at 15 to 24 years (Reijnders et al., 1993).

Abundance and Range

The population of Z.c.californianus was estimated at 145,000 individuals in 1983 (Reijnders et al., 1993). The Marine Mammal Center’s current estimate is 200,000 individuals. Z.c.californianus are found along the Pacific coast of North America from British Columbia southward to Mazatlan and the Tres Marias Islands in Mexico (Odell, 1981). The population of Z.c.wollebaeki was estimated at 30,000 sea lions and is found exclusively on the Galapagos Islands (Reijnders et al., 1993). The Japanese sea lion Z.c. japonicus from coastal Japan is probably extinct. (Reijnders et al., 1993).

Site Fidelity

Females and young (Z.c.californianus) are thought to remain in proximity to breeding rookeries year round, while males migrate north after breeding season ends. Males return to southern rookeries at the start of breeding season. Migratory patterns for Z.c.wollebaeki are unknown (Odell, 1981).

Ease of Census

Moderate

Feeding Habits

Little is known about the feeding behavior of the California sea lion, however, it has been noted that they may feed both at night and during the day, and that their excellent dark vision assists in foraging in deep waters (Odell, 1981). Sea lions feed opportunistically on fish and cephalopods, including Pacific whiting, rockfish, anchovy, hake, flatfish, small sharks, squid, and octopus (Reidman, 1989). Sea lions were observed to forage in large groups when extensive schools of fish or squid are present. Sea lions are capable of diving to depths of 170 and 250 meters (Odell, 1981).

 

Sea Lion Contaminant Exposure Data

I.

Organochlorine Contaminants

1.

Blubber, brain, muscle, and liver samples taken from sick and healthy sea lions collected from central California beaches (including San Miguel and Ano Nuevo Islands) between September 19 and December 10, 1970 were examined for DDT contamination (LeBoeuf and Bonnell, 1971). The following mean concentrations of SDDT were found in the sea lions and are listed in order of (μg/g wet wt./ μg/g lipid wt.): Healthy-killed (blubber, n=5, 906 / 1220; brain, n=4, 8.6 / 85). Sick-killed (blubber, n=6, 689 / 1022; brain, n=5, 13 / 140). Fresh carcasses (blubber, n=14, 1006 / 1687; brain, n=6, 14 / 173). Total of all specimens (blubber, n=25, 911 / 1452; brain, n=15, 12 / 138).

The following mean percentages of DDT metabolites (using μg/g lipid wt.) were found in the sea lion tissues that were analyzed: blubber, n=26 (DDE=93.9 %, DDD=3.9%, DDT=2.2%) and brain, n=15 (DDE=94.1%, DDD=3.3%, DDT=2.6%).

Blubber and brain samples were taken from a single fresh sea lion carcass immediately upon death and at 2 days and 5 days following death. The ΣDDT concentrations (μg/g lipid wt.) found were as follows and are listed in order of (day 0, day 2, day 5): blubber (1267, 1167, 1268); brain (146, 147, 147).

Muscle (N=4) and liver (n=7) tissue samples taken from healthy sea lions were analyzed for ΣDDT. The following mean concentrations (μg/g wet wt./ μg/g lipid wt.) were found: muscle (1.2 / 418), brain (17 / 677).

2.

Selected tissues taken from healthy and sick California sea lions found on beaches in Oregon in fall 1970, fall and winter 1971, and October 1973 were analyzed for organochlorine and PCB contamination (Buhler et al., 1975). Tissue samples from Healthy animals were compared with those of Sick animals. The following mean concentrations (μg/g wet wt.) were found in the tissues listed: Healthy Animals: liver (1971, n=6, DDE = 11.1, PCB = 4.87; 1973, n=3, DDE = 12.9, PCB = 2.39); muscle (1971, n=6, DDE = 3.12, PCB = 0.70; 1973, n=3, DDE = 2.65, PCB = 0.36); cerebrum (1971, n=5, DDE = 9.16, PCB = 2.82; 1973, n=3, DDE = 3.02, PCB = 0.49); fat (1971, n=6, DDE = 253, PCB = 34.1; 1973, n=3, DDE = 342, PCB = 21.2). Sick Animals: liver (1970, n=8, DDE = 23.9, PCB = 2.79; 1971, n=2, DDE = 11.2, PCB = 1.95); muscle (1970, n=8, DDE = 3.20, PCB = 0.32; 1971, n=2, DDE = 5.7, PCB = 0.86); cerebrum (1970, n=5, DDE = 8.27, PCB = 1.6; 1971 – No Data); fat (1970, n=7, DDE = 358, PCB = 24.2; 1971, n=2, DDE = 475, PCB = 28.5).

The distribution of DDT metabolites were examined for the sea lion tissue samples. The following are the mean concentrations (μg/g wet wt.) of ΣDDT in each tissue sample followed by metabolite percentages listed as (% DDE / %DDD / %DDT): Healthy Animals: liver, n=5, 11.6 (95.7 / 3.28 / 1.0); muscle, n=2, 3.24 (94.3 / 4.45 / 1.25); cerebrum, n=2, 7.54 (93.3 / 4.10 / 2.55); fat, n=2, 199 (92.7 / 4.10 / 3.25). Sick Animals: liver, n=2, 11.4 (97.6 / 1.65 / 0.40); muscle, n=2, 5.89 (96.9 / 2.56 / 0.60).

3.

Liver and blubber samples taken from premature parturient female sea lions and their pups were analyzed for organochlorine and PCB contamination, and compared to the analysis of samples taken from full- term female sea lions and their pups (Gilmartin et al., 1976). The premature parturient females were collected during March and April 1972 and the full term females were collected in June 1972; both sets of sea lions were collected from San Miguel Island, California.

The following concentrations were found in individual premature partus female sea lions and are listed in respective order of the ten individuals: Blubber samples: DDE (580, 879, 355, 927, 350, NA, 633, 375, NA, 939); DDD (15.1, 15.8, 11.5, 19.7, 8.73, NA, 9.67, 13.7, NA, 18.7); DDT (2.97, 5.56, 4.13, 10.1, 5.74, NA, 4.88, 11.2, NA, 15.8); PCB (49.4, 67.4, 33, 57.5, 47.1, NA, 54.1, 56.4, NA, 92.4); Liver Samples: DDE (26.6, 13.7, 8.54, 24.1, 13, NA, 19.6, 12.4, 20.7, 30.4); DDD (3.22, 0.25, 0.034, 0.157, 0.051, 0.139, 0.273, 0.174, 0.91); PCB (4.34, 3.1, 0.63, 1.22, 0.77, NA, 2.53, 4.13, 4.35, 6.08).

The following concentrations were found in individual full-term partus female sea lions and are listed in respective order of the ten individuals: blubber samples: DDE (82.6, 24.1, 141, 342, 24.3, 16.3, 17.4, 31.5, 23.3, 127); DDD (3.02, 1.17, 2.41, 5.55, 1.14, 1.04, 0.65, 2.65, 1.41, 5.50); DDT (3.09, 1.15, 3.67, 3.87, 2.06, 1.17, 1.84, 2.26, 2.53, 0.72); PCB (12.1, 5.19, 20.8, 39.5, 8.31, 5.39, 4.73, 6.33, 5.16, 24.1). Liver samples : DDE (5.98, 1.42, 4.72, 18.2, 0.93, 1.08, 1.15, 1.38, 1.17, 5.54); DDD (0.41, 0.057, 0.063, 0.15, 0.044, 0.061, 0.028, 0.041, 0.064, 0.087); PCB (1.86, 0.43, 1.07, 1.98, 0.28, 0.19, 0.24, 0.41, 0.43, 1.04).

The DDE concentrations in the blubber and liver of the premature parturient female sea lions were 7.6 and 4.8 times greater (respectively) than corresponding concentrations in full-term sea lions, while PCB concentrations were 4.4 and 3.8 times greater (respectively) than for the same tissues of full-term sea lions. The differences in concentrations of DDE and PCB in both blubber and liver between the two groups (pre-mature versus full-term) are highly significant. The premature parturient females had a significantly higher DDE/PCB ratio than did the full-term parturient female sea lions.

4.

Blubber tissue samples collected from carcasses of sub-adult and adult male sea lions found on beaches in San Mateo and Santa Cruz counties, California between April 1988 and July 1992 were analyzed for DDE and DDT content (Lieberg-Clark et al., 1995). The geometric mean concentrations (μg/g wet wt.) were compared with mean concentrations determined from an earlier study in 1970. The following are the concentrations found: 1988-1992, n=7, DDE = 5.0, DDT = 0.16; 1970, n=12, DDE = 740, DDT = 17. The significant decline in concentrations of both contaminants over the twenty year period was over two orders of magnitude.

5.

Milk samples taken from five pinniped species, including one California sea lion, between January and March 1989 were analyzed for organochlorine and PCB contamination (Bacon et al., 1992). The following concentrations (ng/g wet wt) of individually numbered (#) PCB congeners were found in the sea lion milk sample: #52 (2.8), #44 (8.4), #66 (17), #99 (26), #101 (31), #118 (53), #153 (93), #138 (66), #187 (22), #180 (39), #170 (12), #195 (2). The following organochlorines were found in the sea lion milk (ng/g): p,p’-DDE (1400), o,p’-DDE (3.7), p,p’-DDT (4.3), o,p’-DDT (3.3), p,p’-DDD (29), o,p’-DDD (7.3), trans-chlordane (2.6), trans-nonachlor (4.9), heptachlor epoxide and oxychlordane (0.7), cis-chlordane (4.6), dieldrin (1.1).

6.

Blubber and liver samples from fifteen California sea lions found stranded along the central coast of California from June 1991 to November 1997 were analyzed for organochlorine and PCB contamination (Kajiwara et al., 2001). The sea lions were taken for rehabilitaton to the Marine Mammal Center in California and died during rehabilitation. The following concentrations (μg/g lipid wt.) of the listed contaminants were found in the individual blubber samples (n=13): PCBs (39, 63, 1300, 1100, 1300, 310, 7.2, 13, 520, 32, 18, 24, 840); ΣDDT (130, 180, 540, 2900, 2900, 450, 13, 29, 1200, 110, 60, 71, 140); ΣCHL (2.7, 7.2, 44, 71, 86, 35, 0.51, 1.0, 41, 2.3, 1.1, 2.6, 44); tris(4-chlorophenyl)methane(TCPMe) (0.58, NA, 2.7, 36, NA, 3.0, 0.12, 0.20, NA, 1.1, 0.45, 0.96, NA); tris(4-chlorophenyl)methanol(TCPMOH) (0.47, 1.3, 8.0, 12, 15, 5.1, 0.096, 0.19, 6.0, 0.38, 0.26, 0.36, 7.2); ΣHCH (0.8, 1.2, 4.0, 7.0, 7.0, 2.9, 0.15, 0.25, 4.7, 0.45, 0.10, 0.38, 0.89), HCB (NA for all individuals tested).

The following concentrations (μg/g lipid wt.) of the listed contaminants were found in the individual liver samples (n=9): PCBs (84, 380, 56, 410, 11, 93, 56, 110, 290); ΣDDT (130, 970, 100, 860, 12, 150, 79, 170, 570); ΣCHL (2.6, 37, 4.7, 23, 0.44, 2.4, 2.3, 6.6, 21); tris(4-chlorophenyl)methane(TCPMe) (1.4, 24, 0.68, 50, 0.13, NA, 6.9, NA, 17); tris(4-chlorophenyl)methanol(TCPMOH) (0.66, 5.9, 0.45, 7.5, 0.044, 1.3, 0.51, 2.0, 4.5); ΣHCH (0.71, 2.9, 0.69, 4.5, 0.17, 0.44, 0.26, 0.86, 2.1), HCB (NA for all individuals tested).

The concentration of ΣDDT in the blubber and liver of California sea lions was 15 to 20 times higher than in the two species sampled co ly, the elephant seal and harbor seals. DDE accounted for 97 to 100 percent of the total DDT concentration in the three species of pinnipeds. A significant negative correlation between DDT and PCB concentrations and fat content in the blubber of the sea lions was noted. A significant positive correlation between total DDT and TCPMe concentrations in pinniped tissues was found, suggesting that DDT is a possible source of TCPMe and TCPMOH founding pinniped tissue.

 

7.

Livers from adult California sea lions found stranded and sick on central California beaches from 1994 to 1997 were analyzed for perfluorooctane sulfonate or PFOs (Kannan et al., 2001). The following concentrations (ng/g wet wt) were found in individual sea lions: Female A (38.4), Female B (49.4), Female C (4.6), Female D (20.5), Male A (22.7), Male B (23.7).

             8.

Blubber samples were collected from 18 carcasses of California sea lions stranded between 2000 and 2001 along Todos Santos Bay, Ensenada, Baja California, Mexico (Del Toro et al. 2006).   Samples were collected from juvenile and adult individuals at varying stages of decay.  Contaminants were reported as geometric means and detected at the following levels (µg/g lipid weight): 2.96 total PCBs, 0.01 αHCH, 0.005 γHCH, 0.04 βHCH, 0.003 δHCH, 3.33 DDE, 0.28 DDD, 0.07 DDT, 0.03 γChlordane, 0.11 αChlordane, 0.03 Heptachlor Epoxide, and 0.10 Endosulfan sulfate.  

II.

Cholinesterase-inhibiting pesticides

 

No residue data is available.

III.

Trace Elements, Metals and Metalloids

1.

Liver samples taken from three post-partum female California sea lions and their pups at San Miguel Island, California in 1970 were analyzed for mercury contamination (DeLong et al., 1973). The sea lions were premature parturient females taken 20-24 April. The Hg concentrations (μg/g wet wt ) ranged from 38 to 64, while the Hg concentrations in their pups ranged from 0.4 to 1.8.

2.

Selected tissues from sick or dead California sea lions (n=10) collected on Oregon beaches during October to December, 1970 were analyzed for mercury content (Buhler and Mate, 197 ). The following Hg concentrations (μg/g, wet wt) were found for the ten individual sea lions in the tissue indicated with respective order of individuals in parenthesis maintained: muscle (0.977, 1.65, 1.40, 1.68, 1.29, 1.44, 1.35, 0.795, 2.68, 0.83); liver (91.0, 225, 100, 2.82, 249, 114, 206, 121, NA, 106); kidney (2.03, 4.32, 6.06, 5.15, 3.24, 3.04, 5.17, 2.27, 1.98, NA); heart (NA, NA, 0.721, 0.778, 0.457, 0.817, 0.850, 0.576, NA, NA); pancreas (NA, NA, 0.463, 0.995, 7.09, 3.52, 10.5, 1.53, NA, NA); fat (0.326, 0.196, 0.108, 0.109, 0.067, 0.165, 0.165, 0.138, 0.318, 0.055); cerebrum (0.657, 1.09, NA, NA, 0.656, 0.629, 0.855, 0.326, 1.14, 0.391); cerebellum (NA, 0.618, NA, NA, NA, NA, NA, NA, 0.882, 0.397); spinal chord (NA, NA, NA, NA, NA, NA, NA, NA, 0.698, 0.235); stomach Contents (NA, NA, NA, NA, NA, NA, NA, NA, 0.227, 0.778); hair (NA, NA, NA, NA, NA, NA, NA, NA, 19.7, 11.5).

3.

Selected tissues taken from healthy and sick California sea lions found on beaches in Oregon in fall 1970, fall and winter 1971, and October 1973 were analyzed for mercury and methylmercury contamination (Buhler et al., 1975). Tissue samples from Healthy animals were compared with those of Sick animals. The following mean concentrations (μg/g wet wt.) were found in the tissues listed: Healthy Animals: liver (1971, n=5, Hg = 74.1, MeHg = 2.59; 1973, n=3, Hg = 95.7, MeHg = 1.50); kidney (1971, n=5, Hg = 6.96, MeHg = 0.73; 1973, n=3, Hg = 5.43, MeHg = 0.66); muscle (1971, Hg = 1.23 n=6, MeHg = 1.17 n=5; 1973, n=3, Hg = 0.84, MeHg = 0.84); heart (1971, n=5, Hg = 0.59, MeHg = 0.51; 1973, n=3, Hg = 0.51, MeHg = 0.32); cerebellum (1971, Hg = 0.53 n=3,, MeHg = 0.35 n=2; 1973, n=3, Hg = 0.36, MeHg = 0.15); cerebrum (1971, n=1, Hg = 0.48, MeHg = NA; 1973, n=3, Hg = 0.66, MeHg = 0.14); fat (1971, n=6, Hg = 0.19, MeHg = NA; 1973, NA).

Sick Animals: liver (1970, n=8, Hg = 170.1, MeHg = 3.04; 1971, n=2, Hg = 127.5, MeHg = 2.92); kidney (1970, n=8, Hg = 3.76, MeHg = 0.90; 1971, n=2, Hg = 4.57, MeHg = 0.79); muscle (1970, Hg = 1.64 n=9, MeHg = 1.39 n=8; 1971, n=2, Hg = 1.38, MeHg = 1.36); heart (1970, n=5, Hg = 0.80, MeHg = 0.70; 1971, n=2, Hg = 0.95, MeHg = 0.72); cerebellum (1970, n=3, Hg = 0.90, MeHg = 0.68; 1971, NA); cerebrum (1970, Hg = 0.87 n=8, MeHg = 0.49 n=7; 1971, NA); fat (1970, n=9, Hg = 0.17, MeHg = NA; 1971, n=2, Hg = 0.16, MeHg = NA).

Selected tissues from sea lions were also analyzed for cadmium contamination. The following mean Cd concentrations (μg/g wet wt.) were found and are compared for healthy and sick sea lions: Healthy Animals: liver (1971, n=4, 2.29), (1973, n=3, 1.61); kidney (1971, n=5, 12.0) (1973, n=3, 7.22); muscle (1971, n=5, 0.16), (1973, n=3, 0.085); heart (1971, NA), (1973, n=3, 0.14); cerebellum (1971, n=2, 0.079), (1973, n=3, 0.032); cerebrum (1971, n=2, 0.042); (1973, n=3, 0.032); fat (1971, NA), (1973, n=3, 0.043)

Sick Animals: liver (1970, n=7, 2.35), (1971, n=2, 3.46); kidney (1970, n=7, 9.70) (1971, n=2, 11.5); muscle (1970, n=7, 0.076), (1971, n=2, 0.069); heart (1970, NA), (1971, NA); cerebellum (1970, n=1, 0.061), (1971, NA); cerebrum (1970, n=4, 0.17); (1973, NA); Fat (1971, NA), (1973, NA).

4.

Various sub-samples from the organs, bone and tissues of six immature sea lions collected along the coast of San Luis Obispo between May 1971 and May 1972 were analyzed for lead content (Braham, 1973). The following are the mean lead concentrations ( mg/g, dry wt) found in the listed bones and tissues, in respective order of the six sea lions: humerus (62.8 / 17.5 / 29.1 / 44.1 / NA / 17.7); femur (25.6 / 16.8 / 25.3 / 22.6 / 14.0 / 16.0); tooth (NA / NA / 11.3 / 12.2 / 15.1 / 13.1); rib (14.3 / 11.9 / 8.4 / 14.8 / 0.6 / 0.3); cerebral hemisphere (NA / 7.4 / 0.7 / 8.1 / 1.1 / 0.0); small intestine (1.2 / 0.7 / 3.8 / 12.7 / 1.3 / 0.6); gonad (5.6 / 2.7 / 5.6 / NA / 0.0 / 0.0); cerebellum (NA / NA / 2.2 / 8.2 / 0.0 / 0.2); kidney cortex (NA / 0.6 / 1.8 / 8.8 / 0.7 / 0.4); aorta (NA / 0.8 / 6.0 / 2.9 / 0.3 / 0.1); lung (1.4 / NA / 4.4 / 0.9 / 0.8 / 2.8); kidney medulla (1.6 / 1.1 / 2.7 / 5.1 / 0.8 / 2.8); hair-skin (NA / 1.0 / 3.3 / 3.1 / 0.0 / 0.5); large intestine (1.0 / 0.3 / 4.2 / 2.8 / 0.1 / 0.0); liver (1.2 / 1.0 / 1.6 / 3.0 / 1.0 / 0.2); spleen (1.7 / 0.9 / NA / 2.3 / 1.3 / 0.0); muscle (1.7 / 0.6 / 0.3 / 3.2 / 0.2 / 0.9); stomach (NA / NA / 0.6 / 1.1 / 0.2 / 0.1); fat (NA / 0.3 / 0.0 / 0.6 / 0.0 / 0.03). Lead was found to be significantly higher in hard tissue (bone and teeth) than in soft tissue and was calculated to be significantly higher in females than in males.

5.

Liver and kidney samples taken from premature parturient female sea lions and their pups were analyzed for trace metals and compared to metal analysis of samples taken from full- term female sea lions and their pups (Martin et al., 1976). The premature parturient females were collected during March and April 1972 and the full term females were collected in June 1972; both sets of sea lions were collected from central California beaches.

The following are the mean concentrations (μg/g dry wt) found for the premature mothers and are listed as (liver / kidney): Hg (204 / 7.06); Se (79 / 12.1); Br (38 / 98); Cd (10 / 97); Ag (0.4 / NA); Cu (135 / 29.3); Zn (201 / 149); Fe (1125 / 446); Mn (15.7 / 4.5); K (8800 / NA); Na (3160 / NA); Mg (660 / NA); Ca (113 / NA).

The following are the mean concentrations (μg/g dry wt) found for the full-term mothers and are listed as (liver / kidney): Hg (747 / 28.4); Se (260 / 22); Br (270 / 121); Cd (15.1 / 115); Ag (0.5 / NA); Cu (86 / 22.4); Zn (220 / 173); Fe (2000 / 448); Mn (19.2 / 4.7); K (9190 / NA); Na (4270 / NA); Mg (670 / NA); Ca (99 / NA).

The following are the mean concentrations (μg/g dry wt) found for the premature pups and are listed as (liver / kidney): Hg (1.79 / 0.89); Se (2.9 / 3.7); Br (74 / 85.6); Cu (194 / 19); Zn (425 / 103.5); Fe (4540 / 413); Mn (9.2 / 2.7); K (12820 / NA); Na (8530 / NA); Mg (800 / NA); Ca (574 / NA).

The following are the mean concentrations (μg/g dry wt) found for the full-term pups and are listed as (liver / kidney): Hg (9.56 / 4.62); Se (4.1 / 6.1); Br (53 / 96.7); Cu (146 / 28.4); Zn (505 / 117); Fe (3340 / 280); Mn (12.2 / 2.9); K (12170 / NA); Na (5540 / NA); Mg (810 / NA); Ca (225 / NA).

The following are the concentrations (μg/g dry wt) found for individual samples and listed in respective order of sample number (1 – 10 are the premature / 11 – 29 are the full term):

Livers of sea lion mothers : Hg ( 206, 220, 165, 174, 207, 291, 355, 250, 185, 73 / 966, 308, 502, 874, 912, 284, 1015, 837, 1026, 498); Se ( 78, 91, 64, 59, 75, NA, 151, 92, 73, 28 / 347, 110, 175, 328, 302, 92, 352, 289, 349, 162); Br (26, 51, 36, 56, 27, NA, 26, 36, 45, 39 / 335, 141, 184, 307, 304, 140, 352, 305, 359, 182); Cd (15.3, 8.5, 15.1, 5, 10.4, 14.4, 13.8, 9.8, 7.7, 4.3 / 19.1, 7.8, 12.2, 20.4, 16.4, 5.7, 21.1, 16.2, 17.1, 90); Ag (0.2, 0.4, 0.3, 1.2, 0.3, 0.6, 0.1, 0.5, 0.3, 0.4 / 0.6, 0.7, 0.5, 0.3, 0.5, 0.1, 0.9, 0.4, 0.9, 0.5); Cu (130, 136, 139, 150, 117, 206, 192, 113, 129, 112 / 117, 121, 63, 82, 64, 61, 83, 114, 67, 285); Zn (192, 192, 245, 202, 203, 258, 238, 156, 216, 167 / 239, 212, 217, 266, 176, 166, 288, 220, 196, 346); Fe (1910, 840, 860, 1070, 820, 790, 750, 1760, 1370, 750 / 1340, 730, 1340, 1650, 3420, 2180, 1050, 750, 5590, 750); Mn (21, 16.4, 16, 13.2, 17.5, 16, 16.3, 15.7, 15.2, 10.3 / 17.5, 16.8, 18.9, 17.1, 19.5, 14.7, 23.6, 24.4, 20.3, 20.7); K (8330, 6950, 9820, 8790, 9770, 10400, 8280, 9580, 9000, 8720); Na (1320, 4630, 3540, 3450, 2900, 2740, 2200, 3600, 3300, 3470 / 3830, 4640, 3420, 2890, 5120, 6020, 3060, 4050, 5430, 4170); Mg (620, 560, 690, 850, 660, 690, 560, 780, 630, 580 / 640, 660, 690, 700, 670, 600, 700, 720, 670, 850); Ca (82, 110, 89, 348, 80, 91, 58, 90, 96, 68 / 62, 107, 95, 97, 130, 115, 56, 66, 159, 108).

Kidneys of sea lion mothers : Hg (4.13, 5.58, 5.12, 15.71, 6.31, NA, 5.63, 6.46, 5.31, 9.26 / 25.57, 17, 31.56, 31.84, 34.35, 17.58, 43.15, 21.70, 32.55, 12.05); Se (16.9, 11.6, 11.8, 13.7, 11.1, NA, 10.2, 8.4, 11.8, 13.6 / 19.2, 10, 29.4, 24.5, 28.6, 9.2, 33.8, 21.2, 22.1, 17); Br (99, 105, 71, 104, 98, NA, 99, 104, 104, 100 / 131, 98, 123, 113, 130, 96, 129, 140, 128, 113); Cd (85, 74, 111, 155, 84, NA, 68, 132, 96, 70 / 113, 85, 129, 159, 120, 101, 115, 89, 123, 569); Cu (32.5, 23.7, 26.3, 36.3, 32.9, NA, 23.1, 26.7, 28.6, 33.2 / 23.5, 21.3, 21.2, 23.1, 22.4, 25, 22.2, 21.3, 21.2, 52.3); Zn (135, 158, 151, 195, 139, NA, 129, 131, 144, 156 / 172, 146, 170, 201, 163, 176, 205, 152, 169, 353); Fe (477, 593, 442, 352, 433, NA, 521, 493, 373, 330 / 395, 429, 365, 373, 618, 547, 349, 434, 524, 351); Mn (4.7, 5.8, 4.8, 5, 3.8, NA, 3.6, 4.2, 4.0, 4.9 / 4.1, 4.1, 5.1, 5, 4.9, 4.5, 5, 5, 4.5, 5.6).

Livers of sea lion pups : Hg (1.25, 2.11, 1.13, 0.91, 2.67, 3.19, NA, 1.75, 1.45, 1.61 / 9.71, 7.35, 12.23, 10.83, 15.95, 6.78, 12.64, 6.03, 11.8, 2.28); Se (2.4, 3.1, 2.4, 3.3, 3.7, 3.4, NA, 2.7, 2.1, 3.4 / 4.2, 3.7, 4.7, 5.7, 6, 2.9, 4.1, 2.9, 5.4, 1.9); Br (42, 72, 80, 116, 60, 46, NA, 84, 75, 89 / 48, 39, 52, 54, 49, 46, 54, 50, 79, 64); Cu (233, 293, 87, 57, 386, 314, NA, 158, 139, 75 / 114, 147, 100, 178, 241, 189, 83, 83, 105, 217); Zn (402, 449, 271, 249, 985, 655, NA, 428, 158, 229 / 510, 519, 483, 607, 55, 488, 582, 316, 610, 380); Fe (2060, 6720, 6810, 2700, 8540, 4570, NA, 6780, 1830, 860 / 4470, 2170, 5280, 9120, 1840, 2900, 2820, 1210, 1410, 2140); Mn (9.7, 11.3, 9.8, 4.4, 12.8, 13.3, NA, 11.1, 7.2, 3.2 / 13.7, 16.1, 11.1, 13.7, 13.9, 12.4, 9.5, 8.9, 11.7, 11.2); K (17200, 13430, 6950, 9690, 16080, 16650, NA, 13020, 15000, 7330 / 14450, 13390, 12270, 13140, 10500, 11760, 11900, 12510, 10370, 11440); Na (4700, 7630, 10900, 13170, 7280, 6000, NA, 9590, 8000, 9470 / 5460, 4210, 4760, 5250, 5380, 5070, 3970, 6310, 7820, 7200); Mg (810, 900, 690, 790, 890, 910, NA, 800, 940, 500 / 920, 850, 750, 900, 820, 840, 710, 830, 780, 750); Ca (370, 335, 885, 2250, 162, 290, NA, 332, 220, 325 / 142, 93, 130, 202, 183, 635, 110, 380, 207, 163).

Kidneys of sea lion pups : Hg (0.67, 0.79, 0.56, 1.01, 1.13, 1.25, NA, 0.97, 0.82, 0.84 / 4.44, 2.72, 5.48, 4.53, 6.69, 3.8, 6.38, 3.97, 6.63, 1.56); Se (3.1, 4.3, 2.2, 4.1, 3.3, 5.4, NA, 2.7, 4.3, 3.6 / 6.2, 4.5, 8.4, 7.9, 8.2, 3.8, 7.0, 4.7, 6.9, 3.9); Br (82.3, 65.3, 64.7, 74.4, 63.6, 116.4, NA, 100.1, 106.1, 97.8 / 78.1, 76, 110.5, 87.2, 112.2, 87.6, 108.4, 113.9, 98, 94.7); Cu (14.5, 21.1, 16.1, 14.9, 19.5, 31.1, NA, 18.4, 18.5, 17.2 / 29.6, 27.2, 30.1, 26.8, 33.5, 32.6, 25.3, 21.5, 23.9, 33.3); Zn (96.3, 89.1, 93.8, 126.2, 105.8, 112.3, NA, 95.9, 77.6, 134.6 / 116.3, 105.1, 100.8, 120.8, 144.3, 118.6, 136, 97.3, 105.7, 126.6); Fe (253, 417, 598, 629, 288, 240, NA, 273, 395, 626 / 242, 233, 277, 385, 206, 308, 240, 326, 333, 257); Mn (2.9, 2.5, 2.5, 2.4, 2.9, 3.6, NA, 2.3, 2.6, 2.3 / 2.8, 3.3, 2.6, 2.7, 3.6, 3.2, 2.6, 1.5, 3.4, 2.9)

 

6.

Liver and kidney samples taken from healthy California sea lions collected along the Oregon coast were analyzed for metals and metal-binding proteins (Ridlington et al., 1981). The following concentrations of the indicated metals were found in the sea lion tissues ( Kidney μg/g dry wt, Liver μg/g dry wt): Copper (K=5.4, L=40.5); Zinc (K=32.1, L=62.9); Cadmium (K=9.2, L=0).

7.

Liver, kidney, and muscle samples taken from healthy California sea lions collected along the Oregon coast were analyzed for mercury and cadmium (Lee et al., 1977). Additional analysis of tissues determined subcellular distribution of cadmium and mercury. Sea lion livers (n=3) contained concentrations (μg/g ww) of Hg (51.5, 45.6, 122.5) and Cd (1.2, 0.60, 0.68) in whole tissues and had the following subcellular concentration distributions listed in order of ( Nuclear, Mitochondrial, MIcrosomal, Soluble): Sea Lion A Cd (N=0.2, M=0.32, MI=0.1, S=.58), Sea Lion A Hg (N=30.4, M=12, MI=6, S=1.6); Sea Lion B Cd (N=0.16, M=0.02, MI=0.01, S=0.41), Sea Lion B Hg (N=27.7, M=12.3, MI=2.2, S=1.3); Sea Lion C Cd (N=0.26, M=0.12, MI=0.01, S=0.29), Sea Lion C Hg (N=80.9, M=34.5, MI=4.3, S=2.8).

Sea lion kidneys (n=3) contained concentrations (μg/g ww) of Hg (9.6, 1.6, 3.2) and Cd (11.3, 6.1, 3.75) in whole tissues and had the following subcellular concentration distributions listed in order of ( Nuclear, Mitochondrial, MIcrosomal, Soluble): Sea Lion A Cd (N=1.8, M=2.2, MI=0.50, S=6.8), Sea Lion A Hg (N=4.5, M=1.7, MI=1.5, S=1.8); Sea Lion B Cd (N=1.2, M=0.9, MI=0.13, S=3.7), Sea Lion B Hg (N=0.44, M=0.26, MI=0.05, S=0.51); Sea Lion C Cd (N=0.96, M=0.59, MI=0.17, S=3.2), Sea Lion C Hg (N=1.4, M=0.75, MI=0.20, S=1.0).

Sea lion muscle (n=2) contained concentrations (μg/g ww) of Hg (1.03, 0.43) and Cd (0.12, 0.08) in whole tissues and had the following subcellular concentration distributions listed in order of ( Nuclear, Mitochondrial, MIcrosomal, Soluble): Sea Lion A Cd (N=0.040, M=0.004, MI=0.004, S=0.08), Sea Lion A Hg (N=0.91, M=0.003, MI=0.003, S=0.11); Sea Lion B Cd (N=0.05, M=0.013, MI=0.015, S=0.11), Sea Lion B Hg (N=0.36, M=0.003, MI=0.006, S=0.06).

Individual Sea Lion kidney and liver samples were analyzed and found to have the following metal concentrations: Kidney Cd (8, 10, 16, 20, 27), Liver Cd (0.52, 2.2, 2.55, 3.85, 5.0), Kidney Hg (1.11, 1.9, 5.0, 16.0, 27), Liver Hg (3.7, 50, 65, 90, 97).

 

8.

Liver and kidney samples taken from two captive, performing sea lions that died inexplicably after a show on October 24, 1988 were examined for heavy metal contamination (Alexander et al., 1990). The following are the concentrations ( liver μg/g wet weight / kidney μg/g wet weight) that were found where sea lion A is the larger of the two sea lions A and B: Arsenic, A (0.33 / 0.42), B (0.28 / 0.48); Copper, A (48.1 / 11.4), B (65.5 / 15.0), Iron, A (233.0 / 403), B (905 / 343); Lead, A (0.49 / 0.43), B (0.45 / 0.32); Zinc, A (34.0 / 42.0), B (75.0 / 47.0); Selenium, A (49.4 / 32.8), B (88.4 / 22.1). The Se concentration found in blood was: A (5.2) and B (5.1). The mercury concentrations found in brain tissue of A was (0.015) and in the kidney of B was (0.78). In comparison with known significant concentrations of Se in land mammals, the authors considered that blood, liver, and kidney concentrations in these two sea lions were significantly elevated and were the cause of death.

9.

Various tissue samples from an 18 year old captive female California sea lion that died from drowning subsequent to epileptiform seizures were analyzed for metal contamination (van Heeckeren and Skoch, 1987). The tissues analyzed were Brain (B), Liver (L), Heart (H), Muscle (M), Fat (F). The following concentrations (μg/g dry weight) were found for the metals indicated and listed in order of (B, L, H, M, F): Cadmium (B=0.18, L=3.03, H=0.62, M=0.56, F=0.68), Chromium (B=1.37, L=1.66, H=1.51, M=2.39, F=1.24), Copper (B=17.15, L=87.74, H=17.83, M=5.16, F=1.86), Lead (B=77.21, L=77.32, H=94.51, M=79.18, F=110.90), Selenium (B=222.01, L=too high to calculate, H=253.17, M=229.13, F=255.89), Zinc (B=68.45, L=240.28, H=118.59, M=115.18, F=4.89).

10.

Blubber and liver samples from fifteen California sea lions found stranded along the central coast of California from June 1991 to November 1997 were analyzed for butyltin contamination (Kajiwara et al., 2001). The sea lions were taken for rehabilitaton to the Marine Mammal Center in California and died during rehabilitation. The following concentrations (ng/g wet w t.) of the listed butyltin contaminants (MBT or monobutyltin, DBT or dibutyltin, and TBT or tributyltin) were found in the individual liver samples (n=10): MBT (35, 17, 21, 16, 30, 12, 11, 9.2, 21, 46); DBT (24, 20, 14, 7.3, 36, 25, 11, 17, 18, 40); TBT (1.0, 2.5, 2.8, 1.0, 1.7, 2.2, 1.6, 0.8, 0.56, 1.3).

IV.

Petroleum

 

No residue data available.

V.

Other

 

No residue data available.


Sea Lion Contaminant Response Data

I.

Organochlorine Contaminants

1.

Livers, brain and blubber samples taken from post-partum female sea lions and their pups at San Miguel Island, California in 1970 were analyzed for organochlorine contaminants (DeLong et al., 1973). The sea lions were divided into two groups, a premature parturient group (taken 20-24 April) and a full-term parturient group (taken 24-26 June). The following contaminant concentrations (μg/g wet wt ) were compared to determine whether the organochlorine contaminants may be related to premature partus in the California sea lions, listed in order (ΣDDT / PCBs): Premature group, Blubber from female, n=6 (824.4 / 112.4), Liver from female, n=3, (25.24 / 5.74), Brain from pup, n=6 (2.38 / 0.45); Full-term group, blubber from female, n=4 (103.2 / 17.1), liver from female (6.67 / 1.32), brain from pup, n=4 (1.20 / 0.19).

The following differences between the two groups indicates a possible cause and effect relationship between high concentrations of organochlorine contaminants in tissues and early termination of pregnancy in California sea lions: 1) All tissues that were analyzed from females that gave birth prematurely in 1970 contained higher concentrations of total DDTs and PCBs than the tissues of the full-term sea lions. (DDE comprised 80 to 93 percent of the total DDTs content). 2) The brains of premature pups contained twice the residue concentratons as the brains of full-time pups. 3) The PCB concentrations in blubber, liver and brain of the premature parturient group were 6.6, 4.4, and 2.4 times higher than those in the full-term group.

II.

Cholinesterase-Inhibiting Pesticides

 

No response data available.

III.

Trace Elements, Metals, and Metalloids

1.

Selected tissues from sick or dead California sea lions (n=10) collected on Oregon beaches during October to December, 1970 were analyzed for mercury content (Buhler and Mate, 197 ). The concentration levels in the sea lions were compared to documented pathological symptoms. Since the animal with the lowest concentration of mercury (animal 4 had 2.82 μg/g wet wt of Hg in liver) also had the most severe symptoms of mercury poisoning and was very lethargic, there did not appear to be a correlation with mercury concentration in the liver and the severity of the disease symptoms.

2.

Liver and kidney samples taken from two captive, performing sea lions that died inexplicably after a show on October 24, 1988 were examined for heavy metal contamination (Alexander et al., 1990). In comparison with known significant concentrations of Se in land mammals, the authors considered that blood, liver, and kidney concentrations in these two sea lions were significantly elevated and were the cause of death. The following histopathological observations were made concurrently: The brain of sea lion A had areas of perivascular infiltrate of lymphocytes, foci of glial cells, neuronophagia, mild infiltrates of lymphocytes in the meninges and neuronal degenerations. The lesions were similar in the brain of B (smaller sea lion) but were milder. A nonsupperative encephalitis was diagnosed in both sea lions. There were gross lesions in the stomach of sea lion A which were interpreted as necrosis but not confirmed microscopically. Ulcers in sea lion B were chronic and consisted of mucosal necrosis and fibroplasias. Both sea lions’ lungs were hyperemic and had no lesions of pneumonia. The liver, heart, kidneys, testes, pancreas, intestine and mesenteric lymph nodes had no significant lesions in either sea lion. Brain tissues were negative for viral infection.

3.

Various tissue samples from an 18 year old captive female California sea lion that died from drowning subsequent to epileptiform seizures were analyzed for metal contamination (van Heeckeren and Skoch, 1987). The tissues analyzed were Brain (B), Liver (L), Heart (H), Muscle (M), and Fat (F). The sea lion did not have unusual metal concentrations in any tissues except for cadmium and selenium in the liver tissue samples. Selenium may have accounted for two conditions noted in this sea lion that was being rehabilitated in captivity after stranding itself: 1) epileptiform seizures and 2) large amounts of clear yellow fluid in the thoracic cavity as well as a report of anorexia two days before death.

IV.

Petroleum

 

No response data available

V.

Other

 

No response data available


  References for Sea Lion

Alexander, J.W., M.A. Solangi, W.C. Edwards, D. Whitenack. 1990. Selenium toxicosis in two California Sea Lion s (Zalophus Californianus). Proc. Int. Assoc. Aquat. Anim. Med. 21: 25-28.

Bacon, C.E., W.M. Jarman, D.P. Costa. 1992. Organochlorine, and polychlorinated biphenyl levels in pinniped milk from the Arctic, the Antarctic, California, and Australia. Chemosphere 24(6):779-791.

Braham, H.W. 1973. Lead in California sea lion (Zalophus californianus). Environ. Pollut. 5:253-258.

Buhler, D. R., B.R. Mate. 1971. Mercury levels in California sea lions, in Mercury in the Western Environment: Proceedings of a Workshop, Portalnd, Oregon, February 25 – 26, 1971. Continuing Education Publications. Corvallis, OR. 360 pp.

Buhler, D.R., R.R. Claeys, B.R. Mate. 1975. Heavy metal and chlorinated hydrocarbon residues in California sea lions (Zalophus californianus californianus). J.Fish.Res.Board Can. 32:2391-2397.

DeLong, R.L., W.G. Gilmartin, J.G. Simpson. 1973. Premature births in California sea lions: Association with high organochlorine pollutant residue levels. Science 181:1168-1170.

Del Toro, L., G. Heckel, V.F. Camacho-Ibar, Y. Schramm.  2006.  California sea lions (Zalophus californianus californianus) have lower chlorinated hydrocarbon contents in northern Baja California, Mexico, than in California, USA.  Environ. Pollut. 142:83-92.

Gilmartin, W.G., R.L. DeLong, A.W. Smith, J.C. Sweeney, B.W. De Lappe, R.W. Risebrough, L.A. Griner, M.A. Dailey, Peakall, D.B. 1976. Premature parturition in the California sea lion. J.Wildl.Dis. 12:104-115.

Kajiwara, N., K.Kannan, M. Muraoka, M. Watanabe, S. Takahasi, F. Gulland, H.Olsen, A.L. Blankenship, P.D. Jones, S. Tanabe, J.P. Giesy. 2001. Organochlorine pesticides, polychlorinated biphenyls, and butyltin compounds in blubber and livers of stranded California sea lions, elephant seals, and harbor seals from coastal California, USA. Arch. Environ. Contam.Toxicol. 41:90-99.

Kannan, K., J. Koistinen, K. Beckmen, T. Evans, J.F. Gorzelany, K.J. Hansen, P.D. Jones, E. Helle, M. Nyman, J.P. Giesy. 2001. Accumulation of perfluorooctane sulfonate in marine mammals. Environ.Sci.Technol. 35:1593-1598.

LeBoeuf, B.J., M.L. Bonnell. 1971. DDT in California sea lions. Nature 234:108-110.

Lee, S.S., B.R. Mate, K.T. von der Trenck, R.A. Rimerman, D.R. Buhler. 1977. Comp. Biochem. Physiol. 57C: 45-53.

Lieberg-Clark, P., C.E. Bacon, S.A. Burns, W.M. Jarman, B.J. Le Boeuf. 1995. DDT in California sea lions: A follow up study after twenty years. Mar. Pollut. Bull. 30(11):744-745.

Martin, J.H., P.D. Elliott, V.C. Anderlini, D. Girvin, S.A. Jacobs, R.W. Risebrough, R.L. DeLong, W.G. Gilmartin. 1976. Mercury-Selenium-Bromine imbalance in premature parturient California sea lions. Marine Biology 35:91-104.

Odell, D.K. 1981. California Sea Lion, Zalophus californianus in Handbook of Marine Mammals, Volume 1: The Walrus, Sea Lions, Fur Seals and Sea Otter. Academic Press. London, UK. 235 pp.

Peterson, R.S., G.A. Bartholomew. 1967. The Natural History and Behavior of the California Sea Lion. The American Society of Mammalogists, special publications number one. Stillwater, OK. 79 pp.

Reidman, M. 1989. California Sea Lion in California Wildlife Habitat Relationships System. California Department of Fish and Game, California Interagency Wildlife Task Group, Sacramento. 3 pp.

Reidman, M. 1990. The Pinnipeds: Seals, Sea Lions, and Walruses. University of California Press. Berkeley, CA. 439 pp.

Reijnders, P., S. Brasseur, J. van der Toorn, P. van der Wolf, I. Boyd, J. Harwood, D. Lavigne, and L. Lowry. Seals, Fur Seals, Sea Lions, and Walrus. 1-8. 1993. IUCN The World Conservation Union. Status Survey and Conservation Action Plan.

Ridlington, J.W., D.C. Chapman, D.E. Goeger, P.D. Whanger. 1981. Metallothionein and Cu-chelatin: characterization of metal-binding proteins from tissues of four marine animals. Comp. Biochem.Physiol. 70B:93-104.

Van Heeckeren, A., E.J. Skoch. 1987. Potential heavy metal influence on the death of several species of pinnipeds. Proc. Int. Assoc. Aquat. Anim. Med. 18:51-61.

Return to Introduction--BIOLOGICAL AND ECOTOXICOLOGICAL CHARACTERISTICS OF TERRESTRIAL VERTEBRATE SPECIES RESIDING IN ESTUARIES