Harry M. Ohlendorf

EMBRYONIC MORTALITY AND ABNORMALITIES OF AQUATIC BIRDS: APPARENT IMPACTS OF SELENIUM FROM IRRIGATION DRAINWATER

Abstract Severe reproductive impacts were found in aquatic birds nesting on irrigation drainwater ponds in the San Joaquin Valley of California. Of 347 nests studied to late incubation or to hatching, 40.6% had at least one dead embryo and 19.6% had at least one embryo or chick with an obvious external anomaly. The deformities were often multiple and included missing or abnormal eyes, beaks, wings, legs and feet. Brain, heart, liver and skeletal anomalies were also present. Mean selenium concentrations in plants, invertebrates, and fish from the ponds were 22–175 ppm (dry weight), about 12 to 130 times those found at a nearby control area. Bird eggs (2.2–110 ppm) and livers (19–130 ppm) also contained elevated levels of selenium. Aquatic birds may experience similar problems in other areas where selenium occurs at elevated levels.

Selenium toxicosis in wild aquatic birds

Severe gross and microscopic lesions and other changes were found in adult aquatic birds and in embryos from Kesterson Reservoir (a portion of Kesterson National Wildlife Refuge), Merced County, Calif., during 1984. Adult birds from that area were emaciated, had subacute to extensive chronic hepatic lesions, and had excess fluid and fibrin in the peritoneal cavity. Biochemical changes in their livers included elevated glycogen and non-protein-bound sulfhydryl concentrations and glutathione peroxidase activity but lowered protein, total sulfhydryl, and protein-bound sulfhydryl concentrations. Congenital malformations observed grossly in embryos were often multiple and included anophthalmia, microphthalmia, abnormal beaks, amelia, micromelia, ectrodactyly, and hydrocephaly. Mean concentrations of selenium in livers (94.4 ppm, dry weight) and kidneys (96.6 ppm) of birds collected at the Kesterson ponds were about 10 times those found at a nearby control area (8.3 and 12.2 ppm). We conclude that selenium present in the agricultural drainage water supplied to the Kesterson ponds accumulated in the food chain of aquatic birds to toxic concentrations and caused the lesion and other changes observed.

Biogeochemical cycling of selenium in the San Joaquin Valley, California, USA

Subsurface agricultural drainage waters from western San Joaquin Valley, California, were found to contain elevated concentrations of the element selenium in the form of selenate. In 1978, these drainage waters began to replace previous input to Kesterson Reservoir, a pond system within Kesterson National Wildlife Refuge; this substitution was completed by 1982. In the 1983 nesting season, unusual rates of deformity and death in embryos and hatchlings of wild aquatic birds (up to 64% of eared grebe and American coot nests) occurred at the refuge and were attributed to selenium toxicosis. Features necessary for contamination to have taken place included geologic setting, climate, soil type, availability of imported irrigation water, type of irrigation, and the unique chemical properties of selenium. The mechanisms of biogeochemical cycling raise questions about other ecosystems and human exposure.

Ecological assessment of selenium in the aquatic environment.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Background and Need for Workshop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 Workshop Purpose and Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Participation and Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Workgroup Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Workgroup 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Problem formulation: Context for selenium risk assessment . . . . . . . . . . . . . . . . . . . . . 9 Selenium is a global problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Case studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Conceptual model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 How to investigate a potential selenium problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Workgroup 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Environmental partitioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Workgroup 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Bioaccumulation and trophic transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Workgroup 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Selenium toxicity to aquatic organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Workgroup 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Risk characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Importance of problem formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Risk characterization: Unique challenges concerning selenium . . . . . . . . . . . . . . . . . . 26 Risk management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Uncertainties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Overall Workshop Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Appendix: SETAC Pellston Workshop Participants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 List of Figures Figure 1 Conceptual model depicting Se dynamics and transfer in aquatic ecosystems . . . . . . . . . . . . .11 Figure 2 Hierarchy of effects across levels of biological organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 Figure 3 Potential sources of Se to aquatic systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 Figure 4 Selenium species associated with major processes in aquatic systems . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Figure 5 Partitioning of Se among environmental compartments in a typical aquatic system. . . .16 Figure 6 Selenium enrichment and trophic transfer in aquatic food webs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Figure 7 Selenium accumulation in different species of algae, invertebrates, and fish . . . . . . . . . . . . . . . .20 Figure 8 Conceptual pathway of Se transfer in aquatic ecosystems and relative certainty with which Se concentrations in environmental compartments can be assessed in making accurate characterizations of risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28 List of Tables Table 1 Assessment endpoints and measures of exposure and effect for aquatic and aquaticlinked organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 Table 2 Uncertainties and recommendations for future research pertaining to toxicity of Se species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 Ecological Assessment of Selenium in the Aquatic Environment 4

Selenium teratogenesis in natural populations of aquatic birds in Central California

The frequency and types of malformations are described that were encountered during the spring of 1983 in a natural population of aquatic birds exposed to agricultural drainwater ponds and food items containing high concentrations of selenium in central California. A total of 347 nests of aquatic birds containing 1,681 eggs was selected for study at Kesterson Reservoir located in the Kesterson National Wildlife Refuge (NWR), Merced County, California. Embryos collected during incubation or from eggs that failed to hatch were examined to determine the age at death and presence of malformations. Embryonic death was generally high; approximately 17–60% of the nests of different species contained at least one dead embryo. The incidence of malformed embryos was also high; approximately 22–65% of the nests where at least two embryos were examined contained abnormal embryos. American coots (Fulica americana) and black-necked stilts (Himantopus mexicanus) experienced the highest incidence of malformed embryos. For all species, the average percentage of eggs containing dead or live abnormal embryos was 16.1 whereas the average percentage containing live abnormal embryos was 10.7. Multiple gross malformations of the eyes, brain, and feet were often present. Brain defects included hydrocephaly and exencephaly. Eye defects included both unilateral and bilateral anophthalmia and microphthalmia. Eye and foot defects with ectrodactyly and swollen joints were the most common in coots. Beak defects also occurred frequently and most often included incomplete development of the lower beak of ducks (Anas spp.) and stilts. Wing and leg defects were most prevalent in stilts and ducks, with ectromelia and amelia most prevalent in stilts. Other malformations occurring at lower frequencies included enlarged hearts with thin ventricular walls, liver hypopiasia, and gastroschisis. Based upon simultaneous examination of a control population of aquatic birds of the same species and published studies, the incidences of embryonic mortality and deformities were 9–30 times greater than expected. The role of the form of selenium responsible for teratogenesis in laboratory studies is discussed.

Bioaccumulation of selenium in birds at Kesterson Reservoir, California.

This study was conducted to determine selenium (Se) concentrations in tissues of birds collected during the 1983–1985 nesting seasons at Kesterson Reservoir (an area receiving high-Se irrigation drainage water), compare them with birds from reference sites within Californias Central Valley, and relate them to food-chain Se concentrations at the study sites. Within years, Se in livers of adult birds collected early and late in the nesting season changed significantly at both Kesterson and the primary reference site (Volta Wildlife Area). These changes were related to the length of time birds had been present at the study sites and the associated accumulation (at Kesterson) or depuration (at Volta) of Se. All species showed significant location differences, which were greatest in species that occurred at Kesterson throughout the year or fed more consistently within the reservoir. There were few species differences in Se for birds at the reference sites (where food-chain Se levels were “normal” [⩽2 μg/g, dry wt]). At Kesterson (where bird foods generally contained >50 μg Se/g), species patterns varied by year, probably because of varying periods of residence and other factors. Se concentrations in kidneys and livers of American coots (Fulica americana) were significantly correlated (r=0.9845); Se concentrations in breast muscles and livers of juvenile ducks (Anas spp.) also were correlated (r=0.8280). Body weights of adult coots were negatively correlated with liver Se concentration. Lateseason resident breeding birds or pre-fledging juvenile birds reared at a site usually provided the best indication of sitespecific Se bioaccumulation.

Association between PCBs and lower embryonic weight in black-crowned night herons in San Francisco Bay

Reproductive problems, including congenital malformations, reduced hatching success, and decreased survival of hatchlings, have been observed in colonial-nesting water birds at the San Francisco Bay National Wildlife Refuge (SFBNWR). Twenty-four black-crowned night heron (Nycticorax nycticorax) eggs were collected from SFBNWR in 1983. Twelve of these were collected from separate nests when late-stage embryos were pipping, and an additional egg was randomly collected from each nest for organochlorine analysis. Overt anomalies and skeletal defects were not apparent. Embryonic weights (with partially absorbed yolk sacs removed) were 15% lower (p less than 0.05) in SFBNWR embryos compared to control embryos from the Patuxent Wildlife Research Center (PWRC). Crown-rump length and femur length were shorter for SFBNWR embryos. The geometric mean polychlorinated biphenyl (PCB) concentration in SFBNWR eggs was 4.1 ppm wet weight, with a range of 0.8-52.0 ppm. A negative correlation (r = -0.61; p less than 0.05) existed between embryonic weight and log-transformed PCB residues in whole eggs collected from the same nest at SFBNWR, suggesting a possible impact of PCBs on embryonic growth. A correlation with embryonic weight did not occur for DDE [1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene] residues. Liver microsomal aryl hydrocarbon hydroxylase activity was neither significantly elevated nor correlated with PCB, DDE, or PCB plus DDE log-transformed residues. It is unknown whether the apparent association between PCBs and lower weight is persistent through hatching.

Contaminants in foods of aquatic birds at Kesterson Reservoir, California, 1985

Plants, aquatic insects, and mosquitofish (Gambusia affinis) were collected from Kesterson Reservoir, Merced County, California, and a nearby reference site (Volta Wildlife Area) to compare concentrations of three contaminants found in 1985 with those reported in 1983 and 1984. Mean selenium concentrations in food-chain organisms from sites at Kesterson in 1985 ranged from 26.0 μg/g (dry wt) in water boatman (Corixidae) to 119 μg/g in mosquitofish. All mean selenium concentrations at Kesterson were significantly higher than those from Volta and were sufficient to have caused the impaired avian reproduction observed at Kesterson. Boron concentrations were also significantly higher at Kesterson, and, at one pond, the mean concentration in widgeongrass (Ruppia mari-tima) (1,630 μg/g) was high enough to impair avian reproduction. There were no differences in arsenic concentrations between locations, and concentrations in all food-chain organisms (<1.9 μg/g) were lower than those reported to cause adverse effects in wildlife. Within-location differences were observed for all three contaminants at Kesterson and for selenium at Volta, but there was no consistent pattern to these differences. Between-year comparisons showed that selenium concentrations in mosquitofish generally decreased at Kesterson, but remained about the same at Volta over the 3 years. Selenium concentrations in insects from 1985 were lower at Kesterson than 1983, but were similar to 1984. Concentrations in plants were generally higher in 1983 and lower in 1984 compared with 1985. Boron concentrations in plants were generally higher in 1985, but in mosquitofish and insects, boron concentrations remained about the same all 3 years. Most arsenic concentrations did not change significantly between years.

Within- and among-clutch variation of organochlorine residues in eggs of black-crowned night-herons.

Within-clutch variability of DDE and PCB residues in eggs from 62 clutches of black-crowned night-herons (Nycticorax nycticorax) was small (12% and 17%) compared to among-clutch variability (88% and 83%). Significant correlations between concentrations of DDE (median r=0.8885) and of PCBs (median r=0.8244) occurred when 501 correlations were run on two randomly selected eggs from within the same clutch; no significant correlation occurred for either concentrations of DDE (median r=0.0353) or PCBs (median r=−0.0843) when eggs were not restricted to the same clutch but were restricted to the same colony. The probability of finding infrequently detected organochlorine contaminants (e.g., DDT, cis-chlordane) in eggs from the same clutch varied from 43–96% and increased as the chemical became more prevalent and the number of eggs per clutch became smaller. These results further support one of the basic assumptions of the sample egg technique, that the chemical residues in one egg in a clutch accurately reflect residues in the remaining eggs of the clutch.

Mercury, selenium, cadmium and organochlorines in eggs of three Hawaiian seabird species

Abstract Eggs of three representative species of seabirds (wedge-tailed shearwater Puffinus pacificus ; red-footed booby Sula sula ; and sooty tern Sterna fuscata ) were collected in 1980 to determined differences in heavy metal, Se, and organochlorine residues among species nesting in the Hawaiian Archipelago and among the four nesting sites sampled (Oahu, French Frigate Shoals, Laysan, and Midway). Hg and Se were present in all eggs analysed, but Cd was not detected. Hg was usually highest in booby eggs, and there was a southeast-to-northeast trend toward higher concetrations in this species; booby eggs from Midway contained the highest mean concentration of Hg (0·36 μg g −1 , wet weight). Se consistently occurred at lowest concentrations in booby eggs. When Se and Hg concentrations were expressed as nanomoles per gram, Se constituted 94–96% of the combined total at each location for shearwater and tern eggs. In booby eggs, the proportion as Se declined significantly ( α = 0·05) from Oahu (93·4%) westward to Midway (85·9%). Although DDT occurred in most of the shearwater eggs from each site, it was not found in booby or tern eggs. DDE occured in all eggs, but mean concentrations did not exceed 0·6 μg g −1 . DDE concentrations were higher in eggs from the two south-eastern nesting sites and were consistently highest in shearwater eggs. PCBs were found in most of the shearwater and booby eggs, but were not detected in tern eggs. Other organochlorines usually occurred more frequently in eggs of shearwaters than in other species. The only exception were α-HCH and HCB, which occurred more frequently in booby eggs. Kepone, heptachlor epoxide, chlordane compounds, and toxaphene were not detected. Differences in residue concentrations seem to reflect differences in diets and seasonal movements of the birds, and perhaps other factors such as atmospheric and oceanic transport of chemicals and physiological differences among the species.