THE UC DAVIS BIOSENTINEL MERCURY MONITORING PROGRAM: Feedback Tool for Watershed Management

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1 THE UC DAVIS BIOSENTINEL MERCURY MONITORING PROGRAM: Feedback Tool for Watershed Management Darell G. Slotton Shaun M. Ayers Ronald D. Weyand Department of Environmental Science and Policy University of California, Davis

2 Biosentinel Mercury Monitoring Using small, young fish as localized, time-sensitive measures of methylmercury exposure Spatial patterns to a local scale Interannual trends and variability Within-year seasonal trends Performance measures for restoration and remediation

3 Linkage to Aqueous Exposure Aqueous Hg fractions vs small fish MeHg Mid Bear Creek ( )

4 Linkage to Large Fish Mercury Temporally pooled site data regressions Cache Creek watershed ( ) vs adult piscivorous fish (normalized to 270 mm smallmouth bass) Sierra Nevada: Yuba watershed (2002) vs adult rainbow trout muscle Hg (normalized to 250 mm length) Direct site data regressions r 2 = 0.81 p < 0.04 r 2 = 0.94 p < 0.02

5 CALFED Central Area With Heaviest Fish Mercury Monitoring Project Coverage Intensive Sites Index Sites Restoration- Related Sites Yolo Bypass and North Delta Sacramento Mile 44 Petaluma Marsh Napa- Sonoma Marsh San Pablo Bay Suisun Bay Grizzly Bay Suisun Marsh Honker Bay Dutch Slough Prospect Slough Cosumnes McCormack Williamson Tract Frank s Tract San Joaquin Vernalis (40 mi)

6 Entire Biosentinel Monitoring Region Thousands of individual small fish analyses Clear Creek Sacramento Cache Ck Hamilton City Lower Sacramento Series Vernalis San Joaquin Tuolumne Merced Mud Slough Region

7 Biosentinel Program Goals and Objectives Develop baseline data and ongoing performance data at major restoration and remediation sites. Track spatial and inter-annual trends in biotic mercury, at project sites and across the system. Seasonal trends and inter-species relationships at a subset of sites. Help define conditions leading to greater or lesser levels of methylmercury exposure to fish. Refine the use of biosentinels as reliable feedback tools.

8 Central Project Area Primary Species: Mississippi Silverside (Menidia audens)

9 Primary Species in Salmon Restoration Areas: Prickly Sculpin (Cottus asper) Merced Tuolumne Clear Creek (Sacramento ) (San Joaquin, Vernalis)

10 Primary Species in parts of the Delta where sculpin and silversides are scarce or absent: Juvenile Largemouth Bass (Micropterus salmoides) Big Break / Dutch Slough South Delta Dead Horse Slough (Frank s Tract) (Cosumnes ) (San Joaquin ) (Sacramento )

11 Spatial Distribution of Primary Biosentinels Clear Creek Prickly sculpin in salmon tributaries, Sacramento, and San Joaquin at Vernalis Sacramento Hamilton City Mississippi silversides widespread in lower watershed and west Petaluma Marsh Napa- Sonoma Marsh Yolo Bypass, North Delta Suisun Marsh RM 44 Juvenile largemouth bass in Central Delta and rivers Vernalis San Joaquin Tuolumne Merced Mud Slough Region

12 Multiple Individual Fish Analyses (n = 30) Within pre-defined size ranges with consistent Hg Mean Hg ± 95% C.I. 45 ± 2 ng/g Strong statistical power Detailed individual information

13 Fall 1999 UC Davis Silversides Established clear, regional pattern: elevated periphery, lower central Silversides ideal biosentinels: widespread; consistent Hg trends; site-specific

14 Invertebrate Biosentinel and Trout Mercury in Northwestern Sierra Nevada Watersheds ( ) Strong signal of residual, bioavailable Hg Centered on historic gold mining zone Trout Trout muscle muscle (250 (250 g normalized) g normalized) 2 2 Predators Predators 1 1 Predators Predators Drift Drift Feeders Feeders Herbivores Herbivores ppm ppm Hg Hg (dry (dry wt) wt)

15 Silverside Fall 2005 Mercury Spatial Distribution: Entire CBDA Range With Silversides High spots: Yolo Bypass, Cosumnes, Mud Sl Lower in central Delta S Bay Salt Pond Project, Alviso Slough below New Almaden Hg Mine: app. mean silverside Hg (~205 ng/g, ) (90 mi) (40 mi)

16 Seasonal Studies (selected data) Yolo Bypass (Toe Drain) 869 ± Prospect Slough Sacramento Cosumnes ng Hg/g (wet wt) San Pablo Bay Suisun Bay Grizzly Bay Honker Bay Feb-06 Nov high-flooding events: Winter rain flooding Late spring snowmelt flooding May-06 Frank s Tract Jul-06 Sep ±47 San Joaquin San Joaquin Vernalis

17 Methyl Hg concentrations in water vs Mississippi silversides. San Joaquin at Vernalis. Silverside fish water (Water data from Foe et al., Central Valley RWQCB, 2008)

18 Seasonal Studies 869 ±209 Massive spike concentrations after large flooding, July ±2 200 Next year data, 2007, after drought season, no flooding Cosumnes ± San Pablo Bay Suisun Bay Grizzly Bay Honker Bay 25± 2 0 ng Hg/g (wet wt) App. 10-fold decline, year-on-year, July San Joaquin Vernalis

19 Intensive Sites, Multiple Species Data San Joaquin at Vernalis November, 2005 November, 2005: All species uniformly low to moderate in Hg

20 Intensive Sites, Multiple Species Data San Joaquin at Vernalis July, 2006 In July, following major flooding upstream, all species up dramatically

21 Hg (ng/g wet wt. whole body) Intensive Sites, Multiple Species Data San Joaquin at Vernalis Mississippi Silverside Largemouth Bass Prickly Sculpin Threadfin Shad Red Shiner Green Sunfish Logperch Carp Hitch September, Total length (mm) By September, quick-changing species down, indicating reduced exposure; other species declined more slowly

22 Intensive Sites, Multiple Species Data San Joaquin at Vernalis November, 2006 Long-lasting effect in some species: bass, sculpin, red shiner

23 Intensive Sites, Multiple Species Data Cosumnes November, 2005 Note mercury scale ( ng/g); consistently high exposure site

24 Intensive Sites, Multiple Species Data Cosumnes July, 2006 In July, following major flooding upstream, all species up dramatically

25 Intensive Sites, Multiple Species Data Cosumnes September, 2006 By September, quick-changing species down, indicating reduced exposure; residual elevation in other species

26 Intensive Sites, Multiple Species Data Cosumnes November, 2006 Residual, significant elevations persisted in some species

27 Juvenile Largemouth Bass Seasonal Trend At Three, Diverse Intensive Sites Long-lasting, residual flood effect in a more long-term sentinel species

28 Hg (ng/g wet wt, whole body) 140 Suisun Marsh Managed Seasonal Flooding: Suisun Slough North, October through February Feb 7: 100 ± 5 Dec 21: 75 ± 5 Oct 18: 43 ± 3 Oct 6: 44 ± Individual silverside total length (mm) Discharge from seasonally flooded, managed ponds

29 Prickly Sculpin Regional Mercury Trends Merced Tuolumne Clear Creek Significant increase on Sac. Sac R. Hamilton City Sac R. RM44

30 Biosentinels for source identification: Sacramento sculpin series (Fall 2006) Ham. City (100 mi) Feather R Colusa Colusa Drain Drain Cache Ck Yolo Bypass American Approximate 2-fold increase Sculpin data suggest Colusa Drain as a source of MeHg Putah Ck RM 44

31 North Bay Silverside Mercury Trend, Fall 2005, Fall 2006 Town of Petaluma Gambonini Upper Petaluma sites highly elevated Marsh area not relatively elevated Tule Slough (Mid-Petaluma) Black John Slough High marsh: cyclical drying vs ponds - always wet

32 Conclusions Main cases of highly elevated exposure appear to have been associated with some form of episodic flooding: Winter, rain-runoff flooding Sacramento Rice/ Waterfowl Spring, snow-melt flooding Episodic tidal flooding Managed flooding (summer/fall) Petaluma Marsh Napa- Sonoma Marsh Yolo Bypass, North Delta Suisun Marsh Cosumnes Floodplain * Some may have realistic management solutions Vernalis San Joaquin Mud Slough Region