Monitoring Mercury Bioaccumulation in Central Valley & Delta Wetlands

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1 Monitoring Mercury Bioaccumulation in Central Valley & Delta Wetlands Josh Ackerman & Collin Eagles-Smith U.S. Geological Survey, Western Ecological Research Center, University of California, Davis Field Station (4 February 2010)

2 Landscape Factors Influencing MeHg Cycling Sources Habitat Type Land Use Hydroperiod

3 Sacramento-San Joaquin Delta Mosaic of Agricultural, Perennial, Seasonal, and Tidal Wetlands

4 A Mercury Friendly Delta? Lund et al PPIC report

Sediment: Yolo Mercury Study Components USGS-WRD Water Column:

Production Sulfate Reduction S, Fe & C Chemistry Plant-Mercury

metrics Bioaccumulation: USGS-WRD CA DFG Battelle Labs Bachand

5 Sediment: Yolo Mercury Study Components USGS-WRD Water Column: Photodemethylation DOC interactions Hg speciation Loads MeHg Production Sulfate Reduction S, Fe & C Chemistry Plant-Mercury Interactions: Hg Uptake / release Veg / Deveg plots Plant metrics Bioaccumulation: USGS-WRD CA DFG Battelle Labs Bachand Assoc. Invertebrate sampling Caged fish studies USGS-WRD USGS-BRD

6 Yolo Bypass Wildlife Area R31 W32 R64 W65 PW R = White Rice W = Wild Rice PW = Permanent Wetland PW

7 Questions 1) Does Hg bioaccumulation differ among wetland types?! 2) Does Hg increase from wetland inlets to outlets?! 3) Does Hg change over the rice growing season?! 4) Are fish and invertebrate Hg concentrations correlated with MeHg concentrations in water and sediment?! 5) Are biota Hg concentrations above toxic levels?!

8 Bioindicators for Mercury in Wetlands Invertebrates Water boatmen (omnivorous) Backswimmers (predatory) Caged Fish Western mosquitofish Wild Fish Western mosquitofish Mississippi silversides

9 Methods: Caged Fish Experimental Design White Rice Wild Rice Permanent Wetland 3 wetland types 2 replicates per wetland type Cages at inlet, center, and outlet 30 and 60 day exposure

10 Methods: Wild Fish Collected before rice harvest when caged fish removed Analyzed for THg

11 Methods: Invertebrates Collected upon flood-up & before rice harvest Sweep nets & light traps Sorted by species Analyzed for MeHg & THg

12 Caged Fish Exposed in Yolo Wetlands for 60 Days Inlet Center Outlet [THg] (!g g -1 dw) THg Concentration c b a a White rice b c Wild rice a a a Permanent wetland THg burden (!g fish -1 dw) THg Burden a b c White rice a a a Wild rice a b b Permanent wetland Fish at Introduction TMDL Wildlife Threshold! (0.03 ppm ww; 0.15 ppm dw)!

13 High Bioaccumulation Rate in Wetlands [!THg!] (!!!g g! -!1! dw!)! 2.0! 1.5! 1.0! 0.5! 0.0! Caged!mosquitofish! 0! 30! 60! White rice! Wild rice! Permanent wetlands! Increase in 60 Days 12 times higher 6 times higher 3 times higher

Wild Fish at Rice Harvest Inlet Outlet 2.0 A) Wild mosquitofish 2.0 B) Wild silversides [THg] (!g g -1 dw) 1.5 1.0 0.5 * * ns 1.5 1.0 0.5 * * ns 0.0 White rice Wild rice Permanent wetland 0.

14 Wild Fish at Rice Harvest Inlet Outlet 2.0 A) Wild mosquitofish 2.0 B) Wild silversides [THg] (!g g -1 dw) * * ns * * ns 0.0 White rice Wild rice Permanent wetland 0.0 White rice Wild rice Permanent wetland TMDL Wildlife Threshold THg burden (!g fish -1 dw) * White rice * Wild rice ns Permanent wetland * White rice ns Wild rice ns Permanent wetland (0.03 ppm ww; 0.15 ppm dw)

15 Invertebrate Mercury by Time Flood-up Pre-harvest 2.4 Water Boatmen Invertebrate [THg] (!g/g dw) Backswimmers

16 Invertebrate Mercury by Site Inlet 2.4 Water Boatmen Center Outlet Invertebrate [THg] (!g/g dw) Backswimmers

17 Invertebrate Hg not Correlated with Fish Hg Caged gambusia Wild gambusia Caged Mosquitofish [THg] (µg/g dw) Water boatmen [MeHg] (µg/g dw) Wild Mosquitofish [THg] (µg/g dw) Water boatmen [MeHg] (µg/g dw) Wild silverside Backswimmers Wild Silverside [THg] (µg/g dw) 1 Backswimmers [THg] (µg/g dw) Water boatmen [MeHg] (µg/g dw) Water boatmen [MeHg] (µg/g dw)

18 Biota Hg Correlations with Water and Sediment 3 2 Caged Mosquitofish [THg] (ug/g dw) R 2 = R 2 < Water Boatmen [MeHg] (ug/g dw) 1 R 2 = *Water [MeHg] (unfiltered) *Sediment [MeHg] R 2 =0.41 *water and sediment data courtesy of Marvin-DiPasquale, Windham-Myers, Fleck, Alpers, & Stephenson

19 Mercury Risk to Foraging Birds in Yolo Wetlands -Initial Flood-up-

20 Mercury Risk to Foraging Birds in Yolo Wetlands -Rice Growing Season-

21 Mercury Risk to Foraging Birds in Yolo Wetlands -Post Rice Harvest-

22 Mercury Risk to Invertebrate Eating Birds Dietary effect levels for birds! 0.50 µg g -1 dw caused reduced reproduction in mallards (Heinz 1979)! 0.70 µg g -1 dw caused reduced reproduction in kestrels (Albers et al. 2007)! Water boatmen [MeHg]! 75% >0.50 µg g -1 dw! 48% >0.70 µg g -1 dw!

Mercury Risk to Fish Eating Birds Caged Fish Wild Fish >0.03!g/g ww 100% 100% >0.30!g/g ww 52% 26% Central Valley Water Board s TMDL target to protect wildlife*! 0.

23 Mercury Risk to Fish Eating Birds Caged Fish Wild Fish >0.03!g/g ww 100% 100% >0.30!g/g ww 52% 26% Central Valley Water Board s TMDL target to protect wildlife*! 0.03 µg/g ww for Trophic Level 2 fish (<50 mm, e.g. silversides)! Causes reduced reproduction in birds**! 0.30 µg/g ww! *Wood ML, Foe C, Cooke J, Louie SJ, Bosworth DH. Regional Water Quality Control Board Central Valley Region, Sacramento-San Joaquin Delta Estuary TMDL for Methylmercury. Staff Report. February **Albers et al. 2007; Burgess and Meyer 2008

Egg [THg] (µg g -1 fww) 2.0 1.8 1.6 1.4 1.2 1.0 2005-2007 P<0.001* F 2,341 =13.

24 Egg [THg] (µg g -1 fww) P<0.001* F 2,341 =13.58 N=52 failed eggs in successful nests *Statistically controlled for effects of colony site and year

Chick Down Feather [THg] (µg g -1 fw) 20 15 10 5 Newly Hatched Live

25 Chick Down Feather [THg] (µg g -1 fw) Newly Hatched Live chicks Dead chicks 0 Avocets Stilts Ackerman et al., Ecotoxicology, 2008

26 Conclusions 1. Fish Hg highest in rice fields and lower in permanent wetlands! 2. Invertebrate Hg highest in permanent wetlands! 3. Hg increased from inlets to outlets, implying MeHg production in rice fields! 4. Fish Hg increased by 12, 6, and 3 times over reference levels in white rice, wild rice, and permanent wetlands outlets in just 60 days! 5. Hg levels exceeded dietary effects levels for birds and Yolo wetlands should be considered a Hg hot-spot!

27 Future Delta Studies Proposed Cosumnes River Preserve Study! Invited to Submit Full 319h Proposal, Nonpoint Source Grant! Focus on Agricultural & Wetland Management Practices that Reduce Methyl Mercury! Wetland habitats?! Rice: bailing, discing, or mowing rice straw residues?! Seasonal Wetlands: timing and duration of flooding?!

28 Questions? Funding! California State Water Resources Control Board! US Geological Survey! Support! Vic Fazio Yolo Wildlife Area, Dave Feliz, Jack DeWit and DeWit Farms, Yolo Basin Foundation, Yolo Mercury Study Team Members! Contact!

Methylmercury Cycling in Wetlands Managed for Rice Agriculture and Wildlife: Implications for Methylmercury Production, Transport, and Bioaccumulation

Methylmercury Cycling in Wetlands Managed for Rice Agriculture and Wildlife: Implications for Methylmercury Production, Transport, and Bioaccumulation L. Windham-Myers 1, M. Marvin-DiPasquale 1, C. Alpers