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What are the Ecosystem Services Impacts of Mercury Mining and the use of Mercury for Gold Mining? 

Follow the Story Map Below to Find out!
First:
What are Ecosystem Services?

** Ecosystem Services are NOT simply a way to quantify the monetary value of individuals or processes provided by ecosystems, such as carbon budgeting.

Ecosystem Services are the life-supporting benefits humans and wildlife receive from ecosystems such as food, clean air and clean water etc.
(Sukhdev et al, 2008) 

Mercury is a potent neurotoxin that threatens human and wildlife health. What does that mean for the services within the categories of Ecosystem Services?

A synthesis of many mercury studies in the Cache Creek Watershed provides insight into Ecosystem Services impacts as shown by the story map on this page. 

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Thanks to all of the scientists referenced here for their work on this problem. 

Map shows total mercury concentrations in stream sediment at deposition points along Cache Creek and Bear Creek. The background level of mercury in sediment in the Cache Creek Watershed is 0.2-0.4 ppm which was used for the classification (< 0.2 ppm). Data Source: Foe and Bosworth, 2008

Mercury in sediment provides the basis for methylation of mercury and thus biomagnified transfer of methylmercury through the food web (Domagalski et al., 2004)

  • The map to the right shows measurement locations and averages of mercury in silt, sand and gravel per location.

           Data for map: Foe and Bosworth, 2008. 

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  • This map tell an important story. Mercury in stream sediment is highest directly downstream from mine sites. 

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  • The black triangles on the map are mine locations. 

Is the mercury in stream sediment making it into the food web?

  • The map to the right tells an important story considering the map above it.

 

  • Methylmercury measurements in invertebrates are highest downstream from, or in the vicinity of, mine sites. 

Remember, mercury increases in concentration as it transfers to subsequent trophic levels!
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US EPA says mercury in fish
> 0.3 ppm is unsafe! 
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Map shows Methylmercury concentrations in invertebrates throughout the Cache Creek Watershed. Data source: Slotten et al., 2004

What are the levels of mercury in fish in the Cache Creek Watershed?

Fish, birds, amphibians, and other species eat invertebrates!

  • To answer this question, maps of trophic levels 3 and 4 fish were made to better identify Ecosystem Services impacts.

  • Data for these maps: CEDEN scientific data repository http://www.ceden.org/

  • The map to the right shows mercury measurements in trophic level 3 fish.

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  • Trophic level 3 fish are small fish that are commonly eaten by larger fish.

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  • Notice the locations of measurements where mercury is highest in fish is either in the vicinity of or directly downstream from mercury mines.

Average total Hg concentrations (per location) in trophic level 3 fish 1974-2013. Data source: California Environmental Data Exchange Network - http://www.ceden.org/.

US EPA and California EPA safety Thresholds for mercury in fish in California inland waters are shown in this table (Torres, 2017) (US EPA Region 9, 2018).

  • The map above of mercury levels in trophic level 3 fish reveals that average levels are well above the US EPA's and California EPA's safety thresholds for humans and wildlife as listed in the table to the left.

  • "Subsistence" means people who eat fish regularly as a primary source of protein such as Native Americans and low-income people who live around Clear Lake. 

  • The map to the right shows the average mercury levels in trophic level 4 fish at specific measurement locations.

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  • Sport fishermen/women prefer large fish such as Largemouth Bass, Crappie and Catfish which are trophic level 4 fish.

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  • The map shows that trophic level 4 fish in Clear Lake are not safe to eat. 

If mercury levels are so high in trophic level 3 fish, how high are they in trophic level 4 fish?!

  • Invertebrates and fish have clearly been negatively impacted by mercury bioaccumulation in the Cache Creek Watershed. 

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  • Invertebrates and fish are important members of the food web as well as food source for humans

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  • What about birds? They eat invertebrates and fish! 

Map above shows Average total mercury concentrations (per location) in trophic level 4 fish 1974-2013. Data source: California Environmental Data Exchange Network - http://www.ceden.org/.

  • The map on the right shows measurements of methylmercury in Cliff Swallow eggs throughout the Cache Creek Watershed. Data for the map: Hothem et al., 2008. 

 

  • Cliff Swallows eat invertebrates so they are an important ecological indicator of biomagnification of mercury

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  • Lethal amounts of mercury in wildlife have been found to be 0.1 to 1.0 ppm while sub-lethal adverse effects have been found to be in the range of 0.03 - 0.1ppm, which are the levels used for classification on the map (figure 18) (Eisler, 1987).

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The map above shows methylmercury concentrations in Cliff swallow eggs. Data source: Hothem et al., 2008.

Methylmercury measurements in Cliff Swallow eggs in the Cache Creek Watershed are at levels considered to be sub-lethal or lethal.

  • Remember, mercury is a potent neurotoxin.

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  • Neurotoxins impede the ability of the brain to function correctly.

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  • For wildlife this means they may not be able to forage for food or fend for themselves thus possibly decreasing their survival rate

What does all of this mean for Ecosystem Services?

All 4 categories of Ecosystem Services have services within them that have been impacted by mercury mining and/or the use of mercury for gold mining in the Cache Creek Watershed

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Habitat/Supporting Services:

  • Food for wildlife and water quality have been impacted by mercury in the watershed system as shown by the indicator maps.

  • Mercury in invertebrates makes that food source within the food web unsafe as does mercury in fish. 

  • Maintenance of biodiversity may be at risk as well due to the neurotoxic nature of mercury.

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Provisioning Services:

  • Fish are not safe for human consumption as shown by the indicator maps and comparison to the EPA's and California EPA's safety thresholds. 

  • Food as medicine (holistic dietary considerations) has been impacted as well since this important protein and essential fatty acid source is contaminated with mercury.

Regulating Services:

  • Biogeochemistry cycling has been impacted due to the overabundance of mercury (greater than normal background rates) in stream sediment being supplied from point sources (mines). 

  • Water quality has been impacted due to this overabundance of mercury in the watershed system.

  • Erosion prevention has been impacted at mine sites due to lack of vegetation and presence of mine waste.

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Cultural Services:

  •  Cultural experience and/or Sense of Place has been impacted since the watershed and its ecosystem is damaged from mining and fish have unsafe Hg concentrations. Spiritual connectivity to nature is found by many through the act of fishing and preparing the fish for loved ones as a meal to share (Khakza and Griffith, 2016).

  • Cultural Services of recreation and tourism are at risk of being impacted due to Hg levels which may be a threat to local economies. Sport fishing is large part of the economy in the Cache Creek Watershed especially at Clear Lake which is referred to as the Bass Capital of the West (Kukura, 2016).

  • It is possible that fishermen/women will choose a different location for fishing especially considering the signage warning against the ingestion of certain species of fish and the ingestion of fish by women of child-bearing age and children throughout the watershed (figure 24). The local economy could suffer if those sport fishermen/women choose other locations to fish.

  • Those who enjoy whitewater rafting may choose a different river for rafting due to fears of Hg exposure which may also reduce the annual income and impact local businesses.  

Notice some of the methylmercury measurements in invertebrates are greater than

0.3 ppm!

  • Ecosystem Services as a theoretical framework provide the ability to understand holistic ecosystem impacts such as those of mercury bioaccumulation shown in this story map.

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  • Commonly accepted environmental management frameworks, such as Ecosystem Services, increases the ability to manage global-scale environmental problems (Ostrom, 2009).

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  • Applying a framework for environmental management that includes human influence over ecosystems provides for even greater insights. Go to the next section to see the outcome of the employment of Ostroms' SES conceptual model!

Sources for this page:

Domagalski, Joseph L., Darell G. Slotton, Charles N. Alpers, Thomas H. Suchanek, Ronald Churchill, Nicolas Bloom, Shaun A. Ayers, and John Clinkenbeard. 2004. “Summary and Synthesis of Mercury Studies in the Cache Creek Watershed, California, 2001--01.” A Geological Survey. pubs.usgs.gov/wri/wri034335/wri_034335.pdf.

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Eisler, Ronald. 1987. “Mercury Hazards to Fish, Wildlife and Invertebrates: A Synoptic Review.” Biological 10. Contaminant Hazard Reviews. U. S. Fish and Wildlife Service, Patuxent Wildlife Research Center. http://www.pwrc.usgs.gov/eisler/CHR_10_Mercury.pdf.

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Foe, Chris, and David Bosworth. 2008. “Mercury Inventory in the Cache Creek Canyon.” Staff Report. California EPA. http://www.swrcb.ca.gov/rwqcb5/water_issues/tmdl/central_valley_projects/cache_sulphur_creek/cache_crk_rpt.pdf.

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Hothem, Roger L., Bonnie S. Trejo, Marissa L. Bauer, and John J. Crayon. 2008. “Cliff Swallows Petrochelidon Pyrrhonota as Bioindicators of Environmental Mercury, Cache Creek Watershed, California.” Archives Environmental Contamination Toxicology 55: 111–121.

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Khakza, Sorna, and David Griffith. 2016. “The Role of Fishing Material Culture in Communities’ Sense of Place as an Added-Value in Management of Coastal Areas.” Journal of Marine and Island Cultures 5 (2): 95–117.

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Kukura, Joe. 2016. “Get Hooked on Lake County’s Fishing Paradise.” Californa’s Lake County (blog). 2016.

Ostrom, Elinor. 2009. “A General Framework for Analyzing Sustainability of Social-Ecological Systems.” Science 325 (5939): 419–22. https://doi.org/10.1126/science.1172133.

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Slotton, Darell G., Shaun M. Ayers, Thomas H. Suchanek, Ronald D. Weyand, and Anne M. Liston. 2004. “Mercury Bioaccumulation and Trophic Transfer in the Cache Creek Watershed of California, in Relation to Diverse Aqueous Mercury Exposure Conditions.” CALFED. UC Davis. http://loer.tamug.edu/calfed/Report/Final/UCDavis_Cache_Bio_Final.pdf.

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Sukhdev, Pavan, Joshua Bishop, Patrick Ten Brink, Haripriya Gundimeda, Katia Karousakis, Pushpam Kumar, Carsten Neßhöver, et al. 2008. “The Economics of Ecosystems and Biodiversity – An Interim Report.”

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Torres, Tomas. United States Environmental Protection Agency. 2017. “Re: Water Quality Control Plan for Inland Surface Waters, Enclosed Bays, and Estuaries of California -Tribal and Subsistence Fishing Beneficial Uses and Mercury Provisions,” 2017.

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US EPA Region 9. 2017. “Monitoring, Assessment and TMDLs.” US Environmental Protection Agency (blog). 2017. https://www3.epa.gov/region9/water/tmdl/.

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