Mercury in the Biostrome Community of the Great Salt Lake

Transcription

1 Utah State University Watershed Sciences Faculty Publications Watershed Sciences 2009 Mercury in the Biostrome Community of the Great Salt Lake Wayne A. Wurtsbaugh Utah State University Caleb Izdepski Follow this and additional works at: Part of the Aquaculture and Fisheries Commons, Environmental Sciences Commons, and the Fresh Water Studies Commons Recommended Citation Wurtsbaugh, Wayne A. and Izdepski, Caleb, "Mercury in the Biostrome Community of the Great Salt Lake" (2009). Watershed Sciences Faculty Publications. Paper This Presentation is brought to you for free and open access by the Watershed Sciences at It has been accepted for inclusion in Watershed Sciences Faculty Publications by an authorized administrator of For more information, please contact

2 Mercury in the Biostrome Community of the Great Salt Lake Wayne Wurtsbaugh & Caleb Izdepski Utah State University SETAC 2009

3 NASA MODIS Terra Satellite, 12 August 2005 Great Salt Lake Area ~ 4300 km 2 Mean depth 4.5 m Mean Chl a 21 µg/l 110 km NASA

4 Birds Western Hemispheric Shorebird Reserve (1991) Abundant Artemia

5 Great Salt Lake Modifications Gunnison Bay (30% salinity) Railway Causeway Gilbert Bay (10-15%) 15%) Mining District Farmington Bay (0-9%) Automobile Causeway Greater Metropolitan Salt Lake City

6 Extremely high Mercury Levels in the Great Salt Lake Generally, mercury in the Great Salt Lake is times higher than in other lakes that have been measured* Great Salt Lake Total Hg % Methyl Hg 2 8 µg/l % Idaho µg/l ---- Maryland µg/l 1 27% *Data of David Naftz, USGS

7 Source of High Mercury Unknown Natural concentration in salt lake? Long-range atmospheric deposition? Legacy mining contributions & recycling? Current atmospheric Hg deposition to lake 1 is not abnormally high 36 kg/yr Legacy gold/silver mining Hg use in Utah 2 (1864-present) 19,900,000 kg (136,000 kg/yr) 1 Peterson & Gustin (2009) 2 C.L. Ege, Selected Mining Districts of Utah, UGS Misc. Pub

8 River Inflows Farmington Bay South Arm Oxygen Buoy Causeway Gilbert North Bay Causeway Arm 10-15% salinity Fresher, Less Dense Water Fresher, Less Dense Water 30% 0 Oxygen & Sulfide ( mg L -1 ) Deep-brine Layer Deep-Brine Layer Saltier, Denser Water Saltier, Denser Water Depth ( m ) Oxygen Hydrogen Sulfide Mercury methylation rates are likely high: Hg 0 Methyl Hg 7 8 SO = 4 H 2 S 9

9 Few fish, but still there is a Human Health Issue Consumption Advisories on 3 Species of Ducks Northern shoveler Cinnamon teal Goldeneye (Diet: 70 % brine fly larvae)

10 Goldeneye increase Hg levels ~8X after arriving at Great Salt Lake and feeding on brine fly larvae. Vest et al. Mercury (ug / g wet weight) Nov Dec Jan Feb Mar Arp

11 Biostrome Distribution in Gilbert Bay Biostrome Structures Antelope Island Flat, plate-like Oolitic sand 31% Biostromes 11% 11% (23%) (23%) Fine alluvium 7% Seiche-influenced alluvium 4% Beneath deep brine layer (47%) Study Sites Bahamas Photo: Dave Liddell Mounds, ca. 1-m high

12 Distribution in Gilbert Bay Anoxic deep brine layer) Stromatolites (Biostromes) Dominant hard substrate for periphyton, brine fly larvae & pupae Antelope Island Aphanothece sp. (cyanobacteria) Food Web Importance: Principal Brine Fly Habitat Ephydra cinerea

13 Adult fly Simple Food Web Larvae Brine Fly Pupae Cyanobacteria Brine fly larvae Goldeneye, grebes, and adults avocets, gulls, etc.

14 Stromatolite Sampling Methods Brine fly larvae & pupae: Bucket Sampler & SCUBA Scrub stromatolite surface with brush Sampled 5 times (June December) at 3 stations and 2 depths per station Sample pumped to boat & sieved

15 Biostrome Sampling Methods Stromatolite chunks broken off underwater Chl a extracted Periphyton removed - With & without acidification to remove carbonates Adult brine flies collected on shore with net All Hg analyses by cold vapor atomic fluorescence spectrometry at the U.S. Geological Survey Wisconsin Mercury Research Laboratory

16 Abundance of Periphyton on Stromatolites Compared to Phytoplankton Area (km 2 ) A Area (km 2 ) Phytoplankton Periphyton (Stromatolites) Chlorophyll Conc. B Chlorophyll Conc. (mg / m 2 ) Phytoplankton Periphyton (Stromatolites) Total Chlorophyll C Total Chlorophyll (tonnes) Phytoplankton Periphyton (Stromatolites) Periphyton on biostromes is a very important component of primary production for Gilbert Bay *Based on May-October phytoplankton in Gilbert Bay ( ), and summer periphyton values

17 Brine fly larvae very abundant on biostromes Larvae / m 2 30,000 25,000 20,000 15,000 10,000 Brine Fly Larvae Abundance (2008) Station Stansbury Island Kennecott Freemont Island 5,000 0 JUN JUL SEP OCT DEC

18 Dissolved Mercury Concentrations Over Biostromes + sd Mercury ( ng / L ) Dissolved Mercury Draft Data Total Dissolved Hg Dissolved Methyl Hg Station

19 Mercury Concentrations In Brine Flies were High & Increased Significantly Through Successive Stages Total Mercury ( u g / kg dry wt) + S.E ANOVA P < * Draft Data 1 Larvae Pupae Adults ** ***

20 Biomagnification (???) of Mercury in Great Salt Lake Food Web Draft Data 290X Biomagnification Total Mercury (ug / kg) + S.E Water Biostrome Periphyton 1 Larvae Goldeneye* * Winter Concentrations (dry wt) From Vest, J. et al. (2009)

21 Se (ug / L) or (ug / g) +- s.e Selenium Concentrations 4X Biomagnification 0 Water Periphyton Brine Fly Larvae Brine Fly Pupae Brine Fly Adult Goldeneye * Wurtsbaugh, WA (2009) *Goldeneye data from Vest, J. et al. 2009

22 Conclusions Stromatolites/periphyton and brine flies are important in the economy of the lake, and important in the diets of many bird species, likely rivaling the importance of brine shrimp as a food source. Mercury concentrations are high in biostromes and in brine flies, but biomagnification not important in the periphyton brine fly larvae transfer. Goldeneye ducks have very high mercury concentrations: either there is very high biomagnification in the brine fly duck transfer, or the ducks are obtaining mercury from elsewhere.

23 Questions? Funding provided by the Utah Division of Water Quality

24 Avocets Selenium study Hypothesized, literature 48% Misc. Invertebrates Freshwater Periphyton & detritus Gilbert Bay Food Web BN stilts 80% 52% 20% Goldeneye Falaropes Eared grebe Brine Shrimp 70% 56% Calif. gulls 11% 69% Brine fly adults Brine Fly Larvae Biostrome Periphyton Sediment Periphyton/detritus Phytoplankton Sediment Periphyton

25 Substrate Summary: All Sites Density (# / m 2 ) +- s.e Brine Fly Larvae & Pupae Densities (2006) Mud Sand Biostromes