Anchorage Field Office Ecological Services U.S. Fish and Wildlife Service

Transcription

1 Technical Report W AES-TR Habitat Conservation ;--,. Environmental Contaminants TISSUE CONCENTRATIONS OF ELEMENTAL AND ORGANOCHLORINE COI\WOUNDS IN SEA OTTERS FROM TWO ALEUTIAN. ISLANDS IN ALASKA Endangered Species January 1997 Anchorage Field Office Ecological Services U.S. Fish and Wildlife Service

2 TISSUE CONCENTRATIONS OF ELEMENTAL AND ORGANOCHLORINE CO:MPOUNDS IN SEA OTTERS FROM TWO ALEUTIAN ISLANDS IN ALASKA Mark Giger and Kimberly A. Trust January 1997 Ecological Services Anchorage Field Office 605 West 4th Avenue, Room G62 Anchorage, Alaska Fish and Wildlife Service U.S. Department of the Interior USFWS Technical Report WAES-llt-97-01

3 Contents Tables and Figures ii Introduction Materials and Methods Field Methods Laboratory Methods Quality Assurance/Quality Control Results and Discussion Heavy Metals and Trace Elements Arsenic Cadmium Selenium Chromium Mercury Organochlorines and Total PCB Organochlorines Total PCB Conclusions Acknowledgments Literature Cited

4 Tables and Figures Figure 1. Island Locations of Sea Otter Carcass Collections Table 1. Sea Otter Collection Table 2. Sea Otter Tissue Analysis: Metals and Trace Elements (ppm dry wt.)... 5 Table 3. Sea Otter Tissue Analysis: Organochlorines and Total PCB (ppm wet wt.)

5 Introduction The sea otter (Enhydra lutris) population along the coast of Adak, Alaska (51 50' 00" N: ' 00" W) has markedly declined since the late 1980's. Based on surveys of the entire island conducted by the U.S. Fish and Wildlife Service (Service) and the U.S. Geological Survey-Biological Resources Division (BRD) otters have decreased from approximately 2000 in the early 1990s to less than 700 animals by 1996 (Jim Estes, pers. com). Population influences such as emigration, hunting, poaching, and fishery interactions have not been documented (C.Gorbics, pers. com.). More likely factors contributing to this dramatic decline include limited food resources, increased predation by killer whales and exposure to environmental contaminants (J. Estes, pers. com.). Evidence exists which suggests sea otters around Adak may be exposed to elevated concentrations of environmental contaminants, especially organochlorine compounds. Otter carcasses collected in from the Aleutians Islands had higher concentrations of total polychlorinated biphenyls (PCB) in their liver tissue than those collected from either southeast Alaska or California (Bacon 1994). Additionally, concentrations of DDT and DDE were elevated in Aleutian otters. In , four sea otter carcasses were collected on Adak and one from Shemya Island by Alaska Maritime National Wildlife Refuge (Refuge) personnel incidentally and during oil spill beach surveys (Figure 1 ). This report presents the results of organochlorine pesticide, total PCB, and elemental analyses conducted on liver and kidney tissues taken from these carcasses. Materials and Methods Field Methods Beach-cast sea otter carcasses were collected by Refuge personnel (Table 1) and frozen the same day. The otter collected on Shemya Island was frozen and sent to Adak prior to dissection. Carcasses were thawed and dissected in April 1994, by Ecological Services Anchorage Field Office (W AES) and Refuge personnel. Only liver and kidney tissues from intact carcasses were sampled. Approximately 25 g samples were removed with acid washed dissection tools and stainless steel, sterilized scalpel blades. They were placed in pre-cleaned glass jars (I-CHEM 300), frozen, and shipped to analytical laboratories. 1

6 'c ' N Bering Sea~ Alaska ' rv ~ ~ Shemya I. C).. ~.-... '\ : ~ 200 ~I ell.- ~ 0 (/ilh \ () ~, \. 0 0 ~~ Kilometers ~~&~0 Adak I. \s\ands ot:> ~ #~~ Figure l. Locations of Sea Otter Collections

7 Table 1. Sea Otter Collection Collection Date Sample# Sex ~ Carcass Location 07/24/93 Mll6 F < 1 yr Kuluk Beach, Adak 10/29/93 MilS F < 1 yr Adak 01/31/94 Ml21 M 6-7yrs Clam Lagoon, Adak 03/17/94 M137 F yrs Fuel Pier, Adak 03/17/94 M138 M < 1 yr Shemya Island Laboratory Methods Heavy metal I trace element analyses were done by Research Triangle Institute, (Research Triangle Park, North Carolina). Aluminum, boron, barium, beryllium, chromium, copper, iron, magnesium, manganese, molybdenum, nickel, strontium, vanadium, and zinc were measured by Inductively Coupled Plasma Emission following nitric acid preconcentration digestion. Concentrations of arsenic, cadmium, lead, and selenium were measured by Graphite Furnace Atomic Absorption following nitric acid digestion. Concentrations of mercury were measured by Cold Vapor Atomic Absorption following nitric acid digestion. Mercury was reduced by tin chloride (SnCl 4 ) for determination. Analyses for organochlorine pesticides and total PCB were done by Mississippi State Chemical Laboratory (Mississippi State, Mississippi), using the Micro Method as described by the U.S. Environmental Protection Agency (1980). Quality Assurance/Quality Control (QA/QC) Analytical accuracy and precision of metal, organochlorine pesticide and total PCB measurements were assessed via spike recovery and duplicate analysis on 10% of the samples. Data was screened for acceptable QA/QC values based upon the following modified criteria (Quakenbush and Snyder-Conn 1993; K. Mueller, pers. comm.): 1. For accuracy, an average spike recovery between % was acceptable. 2. Precision was quantified by determining a relative percent difference (RPD) based on a comparison of duplicates: RPD = ([0 1 - D:J/(0 1 + DJ/2]) * 100 Where, D 1 =concentration measured in the first analysis and D 2 =concentration measured in the second analysis. 3

8 For samples with both duplicates above the limit of detection, an average RPD <20% was acceptable. 3. For procedural blanks, a concentration <15% of the mean sample concentration was acceptable. Data not meeting these criteria are identified and tabulated in this report. However, further interpretation should be strictly qualitative. Results and Discussion The results (in ppm diy wt.) of elemental analyses are presented in Table 2. The following elements were below the limit of detection and are not reported in the table: barium (<0.5 ppm), beryllium (<0.1 ppm), and lead (<0.8 ppm). All elements met QNQC criteria, except for aluminum (kidney), arsenic (kidney), boron (kidney, liver), chromium (kidney), mercury (kidney), and nickel (liver), which had RPD for duplicates >20%. Table 3 presents the results (in ppm wet wt.) of the organochlorine analyses. The following compounds were below the limit of detection ( <0. 01 ppm) and are not reported in the table: HCB, alpha BHC, alpha chlordane, delta BHC, endrin, gamma BHC, gamma chlordane, mirex, o,p' -DDD, o,p' -DDE, o,p' -DDT, p,p' -DDT, and toxaphene. All elements met QNQC criteria, except p,p' -DDE (liver), which had RPD for duplicates >20%; and p,p' -DDD(liver) and p,p' DDE(liver), which had spike recoveries less than 80%. Although both kidneys and livers were analyzed for all compounds, discussion is limited to the tissue which is either the site of concentration for a particular chemical or is the tissue most referenced in the literature. For some elements, data reference values exist for both tissues, and in such cases concentrations in both tissues are addressed. Heavy Metals and Trace Elements Marine mammals often have presumably elevated concentrations of potentially toxic metals in their tissues, but controlled studies examining the physiological effects of metals in marine mammals are limited to a few experiments in which seals were fed diets containing methylmercury (Law 1996). Therefore, interpreting tissue residue concentrations of metals in relation to health and reproduction in sea otters is difficult because basic toxicological information is lacking, and limited baseline data exists for interspecies comparisons. Additionally, this study only analyzed tissues for chemical residues. No endpoints were measured (i.e., histopathology) which may have indicated physiological impairment. Elemental concentrations are reported in Table 2 on a diy weight basis. However, comparative literature values are often presented in wet weights. In order to remain consistent, data from this 4

9 Table 2. Sea Otter Tissue Analysis: Metals and Trace Elements (ppm dry wt.) Sample ID % Moisture AI As B Cd Cr Cu Fe Hg Mg Mn Mo Ni Se Sr v Zn Kidney M116K <5.13* <0.50* 0.83 <0.10* <0.51* M118K <0.50* <0.50* M121K <0.51* M137K <5.04* <0.50* <0.51* <0.50* M138K <4.99* <0.50* Liver M116L <5.03* <0.51* 1.18 <0.10* <0.50* <0.50* M118L <5.02* 0.87 <0.50* <0.50* <0.50* M121L <5.04* M137L <5.09* <0.51* M138L <5.05* <0.51* <0.51* <0.51* Notes: ( *) Concentration below the detection limit. AI (kidney), As (kidney), B (kidney, liver), Cr (kidney), Hg (kidney), Mn (kidney), and Ni (liver) had duplicates with relative percent differences greater than 20%.

10 Table 3. Sea Otter Tissue Analysis: Organochlorines and Total PCB ( ppm wet wt. ) Sample ID % Lipid %Moisture PCB Total beta BHC cis-nonachlor dieldrin heptachlor epoxide oxychlordane p,p'-ddd p,p'-dde trans-nonachlor Kidney M116K <0.01* M118K <0.01* <0.01* M121K <0.01* <0.01* <0.01* <0.01* <0.01* <0.01* <0.01* M137K <0.01* <0.01* <0.01* <0.01* <0.01* 0.01 <0.01* M138K <0.01* <0.01* <0.01* <0.01* <0.01* Liver M116L <0.01* 0.01 <0.01* <0.01* <0.01* M118L M121L <0.01* <0.01* <0.01* <0.01* <0.01* M137L <0.01* <0.01* <0.01* 0.01 <0.01* M138L <0.01* Notes: ( * ) Concentration below the detection limit p,p'-dde (liver) duplicate had a relative percent difference greater than 20%. p,p'-ddd and p,p-dde(iivers) had spike recoveries less than 80%.

11 study are discussed as dry weights with concurrent wet weight values included in parentheses. Additionally, the following discussion does not include every element reported in Table 2. The individual element summaries are limited to those elements which are known to have adverse effects in marine mammals or other wildlife or there exists literature values for inter- or intraspecies comparisons. Arsenic Arsenic is thought to be a biologically essential element, however the nutritional requirement in marine mammals is unknown (Law 1996). Miles et al. (1992) reported levels of arsenic in harbor seal (Phoca vitu/ina richardsi) liver tissue, collected between from Kodiak, Alaska, ranging from below the limit of detection ( <0. 05 ppm wet wt.) to 0. 9 ppm wet wt. Concentrations of arsenic in sea otter liver tissue collected during this survey ranged from < ppm dry wt. {< ppm wet wt.). Cadmium Cadmium is neither biologically essential nor beneficial (Eisler 1985a). Eisler {1985a) lists concentrations of cadmium in kidney tissue from sea otters ranging from ppm dry wt. Concentrations in kidney tissue collected during this survey ranged from < ppm dry wt. Comparatively, Warburton and Seagars {1993) reported concentrations of cadmium in kidney tissue from Pacific walrus (Odobenus rosmarus divergens) from the Bering Sea ranging from ppm dry wt. Richard and Skoch {1986) reported a mean concentration of cadmium in kidney tissue from northern fur seals (Callorhinus ursinus) from St. Paul Island, Alaska, of ppm dry wt. Although cadmium was measured in liver tissue, concentrations have been found to be consistently higher in kidney than in liver tissue both in cetaceans and in seals (Law 1996). Cadmium is reported to accumulate with age, and this relationship is prevalent in carnivores and marine vertebrates (Eisler 1985a). In both harbor seals (Miles, et al. 1992) and northern fur seals (Goldblatt and Anthony 1983), kidney cadmium concentrations increased with age. Warburton and Seagars (1993) found a similar correlation for Pacific walrus, though it was not strongly represented by a regression model. In an earlier study on Pacific walrus, however, no correlation between cadmium and age was found (Taylor et al. 1989). The two oldest sea otters collected during this survey had the highest concentrations of cadmium, indicating a possible relationship with age. However, the sample size is small, and the survey was not designed to accommodate rigorous statistical comparisons. Selenium Selenium is nutritionally important as an essential trace element, but a comparatively narrow concentration range separates selenium deficiency from selenium toxicity. (Eisler 1985b). Nutritional requirements for marine mammals are unknown. Warburton and Seagars (1993) reported concentrations of selenium in Pacific walrus kidney and liver tissue ranging 7

12 from ppm dry wt. and ppm dry wt., respectively. For sea otter tissues collected during this survey, the range of concentrations in kidney was ppm dry wt. and in liver was ppm dry wt. Selenium has been reported to have an antagonistic relationship with mercury and possibly other heavy metals such as cadmium (Eisler 1985b ). Selenium and cadmium concentrations were positively correlated in liver tissues from minke whales (Balaenoptera acutorostrata), belugas (De/phinapteras leucas), and narwhals (Monodon monoceros) from West Greenland (Law 1996). The data presented here for sea otters suggests a similar relationship. Concentrations of selenium and cadmium are correspondingly higher in kidney and liver tissue samples from the two oldest sea otters, however the data precludes statistical validation. Chromium Chromium is an essential trace element for most species, although at elevated concentrations, chromium is mutagenic, teratogenic, and carcinogenic. Nutritional requirements, tissue accumulation rates and sensitivity to chromium are unknown for sea otters. Concentrations of chromium in sea otter liver tissue collected during this survey ranged from ppm dry wt. Concentrations of chromium in kidney tissue did not meet QA/QC criteria and are considered unreliable. Warburton and Seagars (1993) reported concentrations of chromium in Pacific walrus liver tissue ranging from ppm dry wt. Attributing adverse physiological effects of chromium from tissue residue values would be presumptuous but, available evidence suggests that tissues offish and wildlife containing >4.0 ppm dry wt. may be indicative of chromium contamination (Eisler 1986). Mercury Among mammals, marine pinnipeds usually contain the highest reported concentrations of mercury in tissues (Eisler 1987). Concentrations of mercury in sea otter liver tissue collected during this survey ranged from ppm dry wt. ( ppm wet wt.). Although, mercury and its compounds have no known normal metabolic function, their presence in living cells are potentially hazardous. The concentrations of mercury reported here are not thought to cause adverse physiological effects, and reported relationships of mercury concentrations with age and selenium (Eisler 1987) are not suggested by this data Organochlorines Organochlorines and Total PCB Concentrations of chlorinated organics were low in sea otters from this study. Liver concentrations of DDT and it's metabolites (p,p 1 -DDE and p,p 1 -DDD) were similar to those reported by Bacon (1994). Although, higher than values reported for Southeast Alaskan sea 8

13 otters, concentrations found in the Aleutian otters were significantly lower than those found in California (Bacon 1994). Total PCB Concentrations of total P9Bs in liver tissue from sea otters in this study ranged from ppm wet wt. Bacon (1994) reported mean liver PCB concentrations of0.309 ppm wet wt. from 7 sea otter carcasses collected from the Aleutian islands between Surprisingly, concentrations ofpcbs in tissues of sea otters from the Aleutians were significantly higher than for those collected along the California coast, an area known to be highly contaminated with industrial waste. Sea otters collected from southeast Alaska had significantly lower concentrations ofpcbs than those from California or the Aleutian Islands (Bacon 1994). The total PCB concentrations detected in sea otters from this study are similar to or higher than concentrations causing reproductive impairment in other mustelids. The earliest experimental studies linking PCBs with reproductive problems in wildlife were conducted on ranch mink (Mustela vison). Reproductive failure occurred in mink fed meat from cows that had been given Aroclor 1254 at doses which resulted in liver tissue concentrations ranging from ppm wet wt (Platonow and Karstad 1973). Doses which resulted in liver concentrations of ppm wet wt. were lethal. Additionally, mink died after being fed PCB contaminated fish that resulted in liver tissue concentrations of 4.2 ppm wet wt (Aulerich et al. 1973). However, field studies of marine mammals linking PCB tissue concentrations with toxic effects, particularly reproductive impairment, are limited and most do not control for confounding variables, such as other contaminants, microorganisms and food availability (Kamrin and Ringer 1996). Conclusions Sea otter numbers at Adak, Alaska are declining for unknown reasons. Exposure to environmental contaminants may be influencing otter populations either by causing direct mortality or by impairing physiological or behavioral mechanisms necessary for survival. However, a myriad of chemicals exist that may be potentially toxic to otters. Determining which compounds Adak otters are exposed to is the initial step in discovering the impacts environmental pollutants may be exerting on the population. Opportunistic collection of sea otter carcasses by Refuge personnel resulted in a small sample size, thus precluding rigorous statistical analyses of the data. However, the results may suggest an age-dependent increase of some elements, such as cadmium. Older sea otters had higher concentrations of cadmium in their kidneys than younger animals. Additionally, concentrations of selenium were higher in older sea otters, suggesting a relationship with either age and/or cadmium. Concentrations of other elements of concern (i.e. mercwy and arsenic) were low in sea otter tissues. Concentrations of organochlorine pesticides such as DDT were not elevated in sea otters from this study. However, total liver PCB concentrations were considerably higher than in otters

14 previously collected from the Aleutian Islands (Bacon 1994). The PCB concentrations reported in this study are within ranges known to cause reproductive failure in other mustelids, but physiological implications to sea otters are unknown. Acknowledgments We thank the Alaska Maritime National Wildlife Refuge personnel for carcass collections, especially Jeff Williams and Joe Meehan. We would also like to express our appreciation to Julian Fischer and Angela Palmer for assisting with dissections. Tim Bowman produced the lone figure for this document, and Jeff Williams and Carol Gorbics provided constructive reviews of the paper. Literature Cited Aulerich, R J., R K. Ringer, and S. Iwamoto Reproductive failure and mortality in mink fed Great Lakes fish. J. Reprod. Fertil. 19(Suppl. ): Bacon, C. E An ecotoxicological comparison of organic contaminants in sea otters (Enhydra lutris) among populations in California and Alaska MS Thesis. University of California, Santa Cruz, CA. 56pp. Eisler, R 1985a Cadmium hazards to fish, wildlife, and invertebrates: a synoptic review. Contaminant Hazard Review Reports No. 2. U.S. Fish and Wildlife Service Biological Report 85(1.2). Washington, DC. 46pp. Eisler, R 1985b. Selenium hazards to fish, wildlife, and invertebrates: a synoptic review. Contaminant Hazard Review Reports No. 5. U.S. Fish and Wildlife Service Biological Report 85(1.5). Washington, DC. 57pp. Eisler, R Chromium hazards to fish, wildlife, and invertebrates: a synoptic review. Contaminant Hazard Review Reports No. 6. U.S. Fish and Wildlife Service Biological Report 85(1.6). Washington, DC. 60pp. Eisler, R Mercwy hazards to fish, wildlife, and invertebrates: a synoptic review. Contaminant Hazard Review Reports No. I 0. U.S. Fish and Wildlife Service Biological Report 85(1.10). Washington, DC. 90pp. Eisler, R Arsenic hazards to fish, wildlife, and invertebrates: a synoptic review. Contaminant Hazard Review Reports No. 12. U.S. Fish and Wildlife Service Biological Report 85(1.12). Washington, DC. 92pp. Estes, J.A U.S. Geological Survey-Biological Resources Division, A-316 Earth & Marine Sciences Buildling, University of California, Santa Cruz, California

15 Estes, I. A., C. E. Bacon, W. M Jarman, R I. Norstrom, R G. Anthony, and A. K. Miles Organochlorines in sea otters and bald eagles from the Aleutian Archipelago. In press, Marine Pollution Bulletin. Goldblatt, C. I., and R G. Anthony Heavy metals in northern fur seals (Callorhinus ursinus) from the Priboloflslands, Alaska I. Environ. Qual. 12(4): Gorbics, C U.S. Fish and Wildlife Service. Marine Mammals Management East Tudor Road. Anchorage, Alaska Kamrin, M A., and R K. Ringer Toxicological implications ofpcb residues in Mammals. Pp in Beyer, N. W., G. H Heinz, and A. W. Redmon-Norwood Environmental contaminants in wildlife: interpreting tissue concentrations. SETAC Special Publication Series, CRC, Lewis, NY. 494pp. Law, R Metals in marine mammals. Pp in Beyer, N. W., G. H Heinz, and A. W. Redmon-Norwood Environmental contaminants in wildlife: interpreting tissue concentrations. SETAC Special Publication Series, CRC, Lewis, NY. 494pp. Miles, A. K. D. G. Calkins, and N.C. Coon Toxic elements and organochlorines in harbor seals (Phoca vitulina richardsi), Kodiak, Alaska, USA. Bull. Environ. Contam. Toxicol. 48: Platonow, N. S., and L. H. Karstad Dietary effects of polychlorinated biphenyls on mink. Can. I. Comp. Med. 37: Quakenbush, L. T., and E. Snyder-Conn Pathology and contaminants case report on three Steller's eiders from Alaska Unpublished technical report NAES-TR U.S. Fish and Wildlife Service, Fairbanks, AK. 32pp. Richard, C. A., and E. I. Skoch Comparison of heavy metal concentrations between specific tissue sites in the northern fur seal. IAAAM Proceedings 17: Taylor, D. L., S. Schliebe, and H Metsker Contaminants in blubber, liver, and kidney tissue ofpacific walruses. Mar. Pollut. Bull. 20{9): U.S. Environmental Protection Agency Manual of analytical methods for analysis of pesticides in human and environmental samples. EPA-600/ , Section 5, A{2). Warbuton, J., and D. I. Seagars Heavy metal concentrations in liver and kidney tissues of Pacific walrus. Marine Mammals Management, U.S. Fish and Wildlife Service, Region 7, Anchorage, Alaska 23 pp. 11