Effects of Selenium on American Dippers and Spotted Sandpipers in the Elk River Valley, British Columbia
Draft Final Report, 2002
Disclaimer
This report is the property of The Elk Valley Mines Environmental Management Committee, comprised of the Elkview Coal Corporation, Fording Coal Ltd. and Line Creek Mine Ltd. It may be provided in confidence to government agencies on the Elk Valley Selenium Task Force. The report contains proprietary and business information and may not be shared with people or agencies other than those listed above. It is a work in progress and disclosure of the information contained in the report, beyond the Task Force, could potentially harm the owners of the information.
Executive Summary
Elevated concentrations of selenium have recently been found in water, sediments and aquatic biota in portions of the Elk River and some of its tributaries, particularly those downstream of several coal mines. A government-industry task force, the Elk Valley Selenium Task Force, is directing studies to determine whether adverse effects of selenium may be occurring in various environmental compartments. A consortium of coal mining companies in the Elk Valley, including the Elkview Coal Corporation, Fording Coal Ltd. and Line Creek Mine Ltd. (functioning under the Elk Valley Mines Environmental Management Committee) retained SciWrite Environmental Sciences Ltd. to determine if selenium is affecting waterbirds in lotic (flowing streams) environments. This study complements others that have been completed or are being conducted on fish and invertebrates in lotic environments and fish, aquatic birds and amphibians in lentic environments. The study area includes portions of the Elk and FordingRivers and their tributaries, Line Creek and lower MichelCreek, where elevated levels of selenium have been measured; and reference areas in the upper Elk River, upper MichelCreek, Boivin Creek, AlexanderCreek, Gold Creek and Lynx Creek.
Based on the preliminary analysis and reconnaissance surveys completed in 2001 and discussions with the Elk Valley Selenium Task Force, this study focused on measures of productivity in two species of waterbirds: American dippers and spotted sandpipers. Measures of productivity were the number of eggs laid per nesting pair, the proportion of eggs that hatched and the proportion of those that fledged successfully. Productivity data were collected by observation during the spring and summer of 2002 in exposed (elevated selenium concentrations in water and sediment samples from previous studies) and reference (background concentrations of selenium) streams. To relate observed differences in productivity between exposed and reference areas to selenium concentrations, eggs were sampled from a subset of nests and analyzed for selenium. These eggs were also examined for viability and evidence of teratogenicity.
During March and April, investigators visited survey streams in the southern portions of the study area to determine when American dippers and spotted sandpipers began exhibiting nesting behaviour and to locate pairs and their nesting territories. Streams were surveyed on foot, using binoculars or spotting scopes to locate nests and observe courtship and nesting behaviour. American dippers were present throughout the later winter period, but spotted sandpipers were absent until May 13. Egg collections and quantitative observations of productivity began on May 15. Surveys of productivity continued through mid August.
Eggs were collected under a Canadian Wildlife Service Scientific Permit, which allowed for 14 eggs of each species (seven each from reference and exposed areas). To ensure that both study species (particularly the migratory spotted sandpipers) had time to equilibrate their tissue body burdens of selenium to the local environment, eggs were collected only from birds that had begun laying after at least two weeks in the study area.
Investigators observed broods from as soon as they appeared in May until they dispersed from their nests about mid-August. The data collected included the number of eggs laid, the number that hatched and the number of hatchlings surviving to fledging. After hatching, observers checked nestlings to identify any obvious teratogenic effects or mortality. Dead eggs and nestlings found in or near the nests were collected, examined for external abnormalities, and retained for chemical analysis. In cases of nest abandonment, investigators collected any remaining, unhatched eggs for examination and chemical analysis.
To supplement water and benthos selenium concentration data that had been previously collected in other studies, water and benthos samples were collected from selected creeks. Water samples were collected from the upper Elk River, Gold Creek, Boivin Creek and Lynx Creek. Samples of benthic macroinvertebrates were collected at Gold Creek, Lynx Creek and Boivin Creek. All samples were analyzed by ALS Environmental.
In addition to the productivity study reported here, results of analysis of American dipper feathers collected during October-November 2001 are also reported.
Selenium concentrations in water from Boivin Creek, upper Elk River, Lynx Creek and Gold Creek were <0.001, <0.001, <0.001 and 0.001 mg/L, respectively. Benthos samples from the three new reference creeks had a mean selenium concentration of 1.8 µg/g wet weight. This was less than the mean of 4.2 µg/g wet weight found previously in benthos from two exposed areas (Fording River and Line Creek) and consistent with selenium concentrations in benthos from other studies, which show modest elevations in some samples from reference areas elsewhere in the Elk Valley.
In 45 territories monitored, 36 American dipper pairs built nests and one pair re-nested, making 37 active nests observed. However, nine nests were destroyed by snow and floods, leaving 28 nests from which eggs were collected or observations made. American dipper clutch sizes averaged 4.5 ± 0.5 eggs per nest in the exposed areas and 80% (16 of 20) of them hatched. In the reference areas, clutch sizes averaged 4.4 ± 1.4 and 95% (42 of 44) of them hatched. All of the American dipper pairs that bred produced either four or five eggs except for one pair in a reference area that re-nested after producing three fledglings and then produced three more. Of the eggs that hatched in the exposed areas, 73% (19 of 26) fledged. In the reference areas, 78% (36 of 46) of the eggs that hatched, fledged. There were no significant differences between reference areas and exposed groups for clutch size, hatching success or fledging success. Over the full set of nests for which there was egg selenium concentration data, there was also no correlation between selenium concentrations and eggs laid, eggs hatched or hatchlings fledged. Overall, the mean egg selenium concentration from the exposed areas was slightly higher (1.08 µg/g wet weight) than in the reference areas (0.95 µg/g wet weight), but these differences were not significantly different. No teratogenic effects or dead embryos were observed in American dipper eggs. In the few infertile eggs found, the range of selenium concentrations spanned the range for dipper eggs from lowest (0.6 µg/g) to highest (1.4 µg/g). There was therefore no effect of selenium concentration on egg size or health or on productivity, and no significant differences between exposed and reference areas.
For spotted sandpipers, 82 territories were observed, in which 43 nests were located. In addition to the 14 eggs collected as per the federal scientific permit (seven each from exposed and reference areas), 26 eggs were collected that were observed to be dead in the field, or that were left after nest abandonment and had no chance of successful fledging. Most (19) of these were on the lower MichelCreek. The total sample size was 40 sandpiper eggs, 14 from reference areas and 26 from exposed. The mean egg selenium concentration in the exposed areas was 2.2 ±0.5 µg/g wet wt. and in the reference areas, 1.2 ±0.14. This difference was significant.
Spotted sandpiper clutch sizes averaged 3.8 ± 0.5 eggs per nest in the exposed areas and 75% ((79 of 105) of them hatched. In the reference areas, clutch sizes averaged 4.0 ± 0.0 and 92% (97 of 106) of them hatched. Almost all spotted sandpiper pairs (96%) produced four eggs; one pair produced one egg and three pairs produced three eggs. Of the eggs that hatched, 100% fledged in the exposed (79 of 79) and reference (97 of 97) areas. There were no significant differences between reference and exposed groups for clutch size, hatching success or fledging success. However, the differences in clutch sizes between reference and exposed areas was close to significant, because four nests in the exposed group had fewer eggs and there was total uniformity among the clutches in the reference sites. There was no correlation between selenium concentration and any of the measures of productivity.
No teratogenic effects were observed, but two dead embryos were observed in eggs from a nest on lower MichelCreek. Although two-thirds of both exposed area eggs and reference area eggs were infertile or inviable, there was no significant difference in health status between the exposed and reference sites, and no relationship between selenium concentrations and the eggs’ health status.
The lack of effects is supported by the toxicological literature, which places the threshold for toxicity generally above the mean egg selenium concentrations found in this study. For spotted sandpipers’ eggs, which had higher selenium concentrations than American dippers and significantly more selenium in exposed than in reference areas, the higher concentrations measured in this study were near the reported toxicity thresholds.
This study shows that selenium, although present, is not being taken up through the food chain as much as expected from uptake models in the toxicological literature. One reason might be the mechanism of bioaccumulation. Organic detritus is a key uptake pathway, and depends on bacterial conversion of selenium to organic forms, which occurs mostly the high sediment accumulation and high organic content sediment types that are typical of lentic (standing or stagnant water, such as ponds and swamps) systems. Most studies of selenium uptake and effects have been in such systems. The streams sampled for this study, by contrast, are lotic (rapidly flowing), arising from glaciers and permanent snowfields and running at high velocity over clean boulders and gravel. Such streams have little sediment and short residence times. This results in lower availability of selenium compared to lentic systems as described above. Where this study differs from most in the literature is therefore most likely a lower rate of transfer of selenium from the water phase to the macroinvertebrates via the detrital food web.
Table of Contents
Disclaimer
Executive Summary
Table of Contents
List of Figures
List of Tables
Introduction
Background to the Study
Selenium Toxicology
Selenium Concentrations in the Study Area
Objectives
Biology of the Study Species
Methods
Study Design
Weather Data
Field Collections and Observations
Surveys
Selenium in American Dipper Feathers
Selenium in Water and Benthic Insects
Egg Collections
Productivity Observations
Chemical Analysis
Data Analysis
Statistical Analysis
Results
Weather
Selenium in Water and Benthos
Selenium in American dipper feathers
Selenium in Eggs and Effects on Productivity
American Dippers
Spotted Sandpipers
Discussion
Conclusions
Acknowledgements
References
Appendices
Appendix 1. Chemical Results
Appendix 2. Summary of Productivity Observations
Appendix 3. Feather Clipping Protocol.
Appendix 4. Productivity Results
List of Figures
Figure 1. Study area locations.
Figure 2. 2002 minimum temperature compared to 1980-2001 average for Sparwood, B.C.
Figure 3. 2002 total precipitation compared to 1980-2001 mean.
Figure 4. 2002 total monthly snowfall compared to 1980-2001 mean.
Figure 5. Selenium (µg/g wet weight) in benthic insects (exposed sites from EVS Environment Consultants 2002 for comparison).
Figure 6. Relationship of arsenic, mercury and vanadium to selenium in benthic macroinvertebrates mg/kg wet wt.).
Figure 7. American dippers, productivity results and selenium concentrations (µg/g wet weight in eggs). % hatched and % fledged are given as decimal fractions.
Figure 8. Comparison of mercury and selenium concentrations in American dipper eggs (mg/kg wet weight).
Figure 9. American dipper egg measurements compared to selenium concentrations.
Figure 10. Spotted sandpiper productivity results and selenium concentrations (µg/g wet weight). % hatched and % fledged are given as decimal fractions.
Figure 11. Mean concentration of selenium in spotted sandpiper eggs by site (exposed sites shaded).
Figure 12. Comparison of mercury and selenium concentrations in spotted sandpiper eggs.
Figure 13. Spotted sandpiper egg measurements compared to selenium concentrations.
Figure 14. Mean concentration of selenium in spotted sandpiper eggs by condition.
Figure 15. Hazard profile for selenium in water, benthic macroinvertebrates and birds’ eggs from this study (based on Lemly 1996).
Figure 16. Dose-response curves relating mortality of mallard chicks to mean egg selenium (MES) concentrations (from Fairbrother et al. 2000).
List of Tables
Table 1. Survey schedule.
Table 2. Sampling locations for water and benthos.
Table 3. Metals and selenium in macrobenthic insects (mg/kg wet weight).
Table 4. Metals and selenium in American dipper feathers (mg/kg).
Table 5. Sample sizes and mean egg selenium concentrations and productivity results for each stream for American dippers.
Table 6. Sample sizes and mean egg selenium concentrations and productivity results for each stream for spotted sandpipers.
Table A-7. Results of chemical analysis, American dippers.
Table A-8. Results of chemical analysis, spotted sandpipers.
Table A-9. Summary of Elk Valley American dipper surveys as of August 31, 2002.
Table A-10. Summary of Elk Valley spotted sandpiper surveys as of August 31, 2002.
Table A-11. American dipper egg productivity data (Se is mean egg selenium µg/g wet wt. for the nest).
Table A-12. Spotted sandpiper egg productivity data (Se is mean egg selenium µg/g wet wt. for the nest).
Table A-13. American dipper egg statistics (Se µg/g wet wt., dimensions mm, weightg).
Table A-14. Spotted sandpiper egg data (Se µg/g wet wt., dimensions mm, weightg).
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Introduction
Background to the Study
Elevated concentrations of selenium have recently been found in water, sediments and aquatic biota in portions of the Elk River and its tributaries (Kennedy et al. 2000; McDonald and Strosher 1998, 2000). The selenium concentrations are particularly high downstream of several coal mines. Although selenium is not elevated generally throughout the watershed, based on concentrations found in water, somewhat elevated concentrations occur in biota from some locations.
Despite selenium concentrations above generally accepted criteria for the protection of aquatic life and wildlife (Environmental Protection Agency 1998; Nagpal and Howell 2000) in creeks affected by mine water runoff, apparently healthy, breeding populations of fish (McDonald and Strosher 1998) and birds (SciWrite Environmental Sciences Ltd. 2001a) are present throughout the area. A government-industry task force, the Elk Valley Selenium Task Force, is directing studies to determine whether adverse effects of selenium may be occurring in various environmental compartments. A consortium of coal mining companies in the ElkValley, including the Elkview Coal Corporation, Fording Coal Ltd. and Line Creek Mine Ltd. (functioning under the Elk Valley Mines Environmental Management Committee) retained SciWrite Environmental Sciences Ltd. to determine if selenium is affecting waterbirds in lotic (flowing streams) environments. This study complements others that have been conducted or are being conducted on fish and invertebrates in lotic environments (EVS Environment Consultants 2000) and fish, aquatic birds and amphibians in lentic environments (Minnow Environmental Inc 2002).
The study area includes portions of the Elk and FordingRivers and their tributaries including Line Creek and lower MichelCreek, where elevated levels of selenium have been measured. In addition, reference areas including the upper Elk River, upper Michel Creek, Boivin Creek, Alexander Creek, Gold Creek and Lynx Creek were studied (Figure 1).
Figure 1. Study area locations.
Selenium Toxicology
Selenium bioaccumulates and has a wide variety of toxic effects in birds, including metabolism, growth and reproduction. In birds (and other taxa) selenium most obviously affects reproduction through mortality (of the egg or hatchling) and teratogenesis. Elevated dietary intake of selenium can cause dramatic teratogenic and other reproductive effects in waterbirds at dietary levels only a few times greater than those that are nutritionally essential. Teratogenic deformities can include anophthalmy (no eyes), spinal and bill deformations, defects in internal organs and histological abnormalities. Selenium can cause teratogenic effects and mortality in embryos and chicks even when adults seem unaffected. Reproductive effects in fish and aquatic birds are the most sensitive biological indicators of aquatic ecosystem-level impacts of selenium (Lemly 1999) and bird-egg residues are the best tool for assessing potential risk to birds from selenium (Adams et al. 1998).
Most of the field studies of selenium toxicity in birds have been in lentic systems. By contrast, lotic (rapidly flowing) systems, which predominate in the study area, have not been well studied. This study was designed to determine whether any effects that could be associated with selenium are observable under field conditions in lotic environments of the study area.
Selenium Concentrations in the Study Area
Earlier studies (Kennedy et al. 2000; McDonald and Strosher 1998) found water concentrations in creeks exposed to coal mine runoff – Erickson Creek and Line Creek and the Fording River – in the 20 μg/L to 60 μg/L range, while reference sites in the Elk River had 1.0 μg/L or less. UpperMichelCreek had intermediate values from around 2.0 μg/L to over 5.0 μg/L . In sediments, quite low concentrations of 1.3 μg/L were found at an Elk River reference site and from 1.8 μg/L in Line Creek to 2.4 μg/L in lower MichelCreek and 2.4 μg/L in the FordingRiver. More recently, selenium concentrations of around 15 – 25 µg/L have been found in the Fording River and Line Creek, over 9.0 µg/L in Michel Creek and up to around 130 µg/L in Erickson Creek (M. Graham, Elkview Coal, unpubl. data in lit. to L. Harding, December 12, 2002). Benthic macroinvertebrates in those studies had less than 2.0 mg/kg dry weight selenium at an Elk River reference site and from 4.3 mg/kg dry weight to 10.7 mg/kg dry weight selenium in the FordingRiver and Michel and Line Creeks. Fish had a mean of 21.0 mg/kg dry weight selenium (Kennedy et al. 2000). Based on the selenium toxicity of Lemly (1996), these values suggest a high hazard of selenium toxicity in parts of the Fording River and Line and lower Michel Creeks to insectivorous waterbirds based on the concentrations in water and aquatic invertebrates, but a low hazard based on the sediment concentrations (Lemly 1996). Moreover, the studies suggested that selenium was not partitioning among the environmental media as it does in many other areas; and the relative lack of toxicity in fish suggested than selenium in this environment is less biologically active that in other situations (see Discussion).