Fish Mercury in the Everglades: Management Implications for Everglades Restoration Ted Lange, Fish and Wildlife Research Institute, FWC
Collaborators/Acknowledgements SFWMD Water Quality Monitoring Section, South Florida Water Management District, West Palm Beach Florida DEP Division of Environmental Assessment and Restoration, Florida Department of Environmental Protection, Tallahassee Florida DOH Bureau of Epidemiology, Division of Disease Control and Health Protection, Florida Department of Health, Tallahassee USGS Mercury Research Laboratory, Madison WI FGCU Coastal Watershed Institute, Ft Myers
Current Sport Fish THg in FW EPA WCA1, WCA2, WCA3, and ENP-Harvestable size USEPA Human Health MeHg Tissue Criterion = 0.3 mg/kg 3.5 3.0 2.5 Black bass Bluegill Redear Sunfish Spotted Sunfish Warmouth Brown Bullhead Yellow Bulhead Bowfin Mayan Cichlid Bullseye Snakehead Butterfly Peacock Blue Tilapia Spotted Tilapia Alligator (2011) Pig Frog (2008) 2.0 1.5 1.0 Fillet THg (mg/kg) 0.5 0.0 Black Bass Sunfish Catfish Bowfin Exotic Alligator Frog
S. FL. Black Bass vs State FWC Regions-Harvestable size USEPA Criterion - 0.3 mg/kg 2.5 2.0 Lake River Canal Marsh NW Lake NW River NW Canal NW Marsh NC Lake NC River NC Canal NC Marsh NE Lake NE River NE Canal NE Marsh SW Lake SW River SW Canal SW Marsh South Lake South River South Canal South Marsh 1.5 1.0 THg (mg/kg) 0.5 0.0
Human and Ecological Risk Fish & Wildlife TL3= Carnivores feeding on Omnivores (YOY and MOSQ) 0.20 Prey Fish THg (mg/kg) 0.15 0.10 0.05 0.00 E Lk Tohopekaliga Lk Tohopekaliga Hillsborough Riv Peace Riv Lk Istokpoga STA1 West L-7 Canal LNWR Marsh Holeyland WMA WCA2U3 Marsh L-35B Canal L-67A Canal WCA3A15 Marsh ENP Lostmans Cr ENP North Prong Cr 2.0 1.5 1.0 0.5 Chipola Riv Suwannee Riv 0.0 Left Axis: Bass USEPA Human Health (0.3 mg/kg) Bass EHg3 (2001-14) Right Axis: Mosq and YOY Bluegill USEPA WL @ TL 4 (0.346 mg/kg) USEPA WL @ TL 3 (0.077 mg/kg) MOSQ THg (mg/kg) 2009-14 YOY THg (mg/kg) 2008-15 Bass EHg3 (mg/kg)
Ecological Risk Fish Wild Fish Pop Effects (MeHg in Diet) Depew et al. 2012 Growth 2.5 mg/kg Behavior 0.5 mg/kg Reproduction sub-clinical effects - <0.2 mg/kg 1.0 EPA Sites Whole slot Bluegill (102-178 mm) 100 Grass shrimp Crayfish Small fish Large fish Herps 0.8 80 Mean THg (mg/kg) 0.6 0.4 % by weight 60 40 20 0.2 0.0 1998 2000 2002 2004 2006 2008 2010 2012 2014 0 <200 200-299 >300 Size class U3 Bass
Compartmentalized EPA-Site Specific Trends 0.35 0.30 WCA2U3 0.25 0.20 0.15 0.10 r = 0.788, p = 0.0001 0.05 1998 2000 2002 2004 2006 2008 2010 2012 2014 0.30 WC33ALT 0.25 0.20 0.15 0.10 r = 0.676, p = 0.01 0.05 1998 2000 2002 2004 2006 2008 2010 2012 2014 Water Year Slot Bluegill (102-178 mm) Increasing Trends 2 locations
0.8 Compartmentalized EPA WCA-1 0.6 0.4 0.2 0.0 0.8 WCA-2 0.6 0.4 0.2 0.0 0.8 0.6 0.4 WCA-3 Total Mercury in Sunfish (mg/kg, wet wt) 0.2 0.0 0.8 ENP 0.6 0.4 0.2 0.0 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Mean THg in TL3 sunfish WY1999 WY2013. Error bars = 1 SD. Water Year
Trends in Bass WCA1, 2 and 3 Restricted Cubic spline with knots selected to best fit data. 1988 to 2001 - Decline (t 4023 = -27.86, P < 0.001). 2001 to 2013 - Increase (t 4023 = 5.38, P < 0.001) ENPSRS 1989 to 2014-Delcine (F 5,691 = 5.85, P < 0.001)
Risk Management-Consumption Advisories Based on USEPA MeHg Rfd of 0.1 µg / kg BW day Encourages 2 fish meals/week FL Dept of Health Criteria Sensitive population: Women of childbearing age and young children General population: All other individuals Florida Department of Health Guidelines Meal Frequency 1 Sensitive Population General Population 2 meals per week < 0.1 mg/kg < 0.3 mg/kg methylmercury 2 methylmercury 1 meal per week < 0.2 < 0.6 1 meal per month < 0.85 < 1.5 DNE > 0.85 > 1.5 Seek to encourage consumption of fish for health benefits but guide decisions toward selecting fish meals low in mercury.
Managing Public Health-Advisories FW Fish Consumption Recommendations LOCATION SPECIES Sensitive All Others WCA2A Mayan cichlid 1/WK 2/WK Bluegill, Redear sunfish 1/MO 2/WK Butterfly Peacock, Spotted Sunfish, 1/MO 1/WK Bass < 14" Bass > 14 DNE 1/MO LOCATION SPECIES Sensitive All Others Other Advisories Pig frogs, Alligators 55 Coastal species; 7 are elevated in FL Bay & Keys ENP SRS Redear sunfish, Gray snapper 1 / MO 2 / WK Bluegill, Spotted sunfish 1 / MO 1 / WK Mayan cichlid 1 / MO 1 / MO Common snook, Red drum, Bass < 14", Yellow bullhead catfish DNE 1 / MO Bass > 14 inches DNE 1 / MO
Managing Public Health- Alternatives Direct Harvest away from EPA Urban Fisheries STAs-Alligator hunts, fisheries Other CERP Projects Exploit new species Mean THg (mg/kg) 0.30 0.25 0.20 0.15 0.10 0.05 0.00 BUSN MACI RESU Fillet THg (mg/kg) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 Alternative Bass Fisheries EPA STA Urban Canals Bullseye Snakehead Channa marulius Excellent edibility; up to 15 lbs, top-water baits
Managing Sources-EPA Nearly all of the Hg entering the EPA is derived from atmospheric deposition. Deposition remains relatively constant with an N-S increase in loading Deposition of mercury and subsequent methylation is the source of MeHg in EPA biota FL BAY: Atm Dep likely more important than inflows (Rumbold 2010) E-MCM predicts decadal timeframe for reductions in fish THg Immediate response Protracted due to labile sed mercury supporting methylation DEP, 2003. Integrating Atmospheric Mercury Deposition and Aquatic Cycling in the Florida Everglades TMDL Approach.
Statewide Mercury TMDL (October 2013) DEP completed a statewide TMDL for mercury in fresh water and estuaries in September 2012. Two Approaches for risk assessment Market Basket: examine distributional characteristics of fish consumption by the sensitive population and the likelihood of mercury exposure from eating fish. Indicator species: calculate a reduction factor for 90% of largemouth bass populations to reach desired target for consumption Both approaches support reductions to limit human exposure 86% reduction from all emission sources (local, regional, and global) Waste load allocation of 23 kg/yr (MINIMAL)
Mercury TMDL for the state of Florida Appendix F: Deterministic Atmospheric Modeling and Receptor Modeling Figure 7. Annual (2009) total mercury deposition (μg/m2) results from CMAQ partitioned into Florida and non-florida sources (partition based on Florida and non-florida tags) for 7 sites.
Statewide Distribution in Bass THg15 < 0.20 ppm 0.20 0.49 ppm 0.50 0.99 ppm > 1.0 ppm Deposition, Methylation and bioaccumulation of Hg into the food web is a statewide issue
Managing Methylation and Bioaccumulation Processes Everglades: Hydrologically altered and spatially fragmented EPA consists of nearly independently operating Marsh Impoundments where methylation processes, Varies between impoundments Varies within impoundments along gradients of biogeochemical parameters (e.g. Organic Carbon, Sulfate, and Nutrients) which are influenced by management (Quantity and Quality of surface waters). Similarly, bioaccumulation processes vary across the EPA
Managing Mercury Bioaccumulation: Influence of Food Webs on Biota MeHg 3.00 Whole-body Hg (µg/g) 2.50 2.00 1.50 1.00 ENR U3 L35B L67A 3A15 0.50 0.00 <200 200-299 300-399 >400 Size class (mm) Can Variability in Fish Hg concentrations can be explained by site specific characteristics (length/complexity of food web, trophic position, growth, and availability of MeHg)
Fish and prey mercury varied by location and trophic position All Sites WCA3 Site 3A15 Log THg (ng/g ww) 4 3 2 1 0 LB CPIK BOW CPIK FGAR FGAR FGAR FGAR BLCR FGAR BOW RPIK SPSU CPIKYEBU SPSU BLCR CPIK BLCR RESU SPSU FROG SPSU SPSU BOW RESU YEBUYEBU FGAR YEBU RESU YEBU SPSU YEBU RESU YEBU RESU RESU BLCR BOW FROG YEBU YEBU YEBU YEBU LUE FGAR FGAR MACI SPSU SPSU RESU RPIK SPSU SPSU MACI FROG RESU SPSU SPSU SPSU YEBU RESU SPSURESU SPSU BLCR RESU RESU RESU SPSU WACA SPSU YEBU RESU SPSU SPTI RESU RESU LACH RESU SPSU SPTI RESU RESU RESU RESU FGAR RESU RESUGOSH YEBU GOTO GOSH SPSU GOTO SPSU SPSU LACH GOSH GOSHGOSH LACH GSHR RESU RESU SPSU RESU GOSH RESU RESU GOSH LACH LACH LACH GAFL GOSH BLKI GOSH CRAY GOTO LEKI LACH RESU FGAR BLCR GOSH SEKI SPSU BOW YEBU BLCR FGAR LACH WGYR GOSH GSHR LACH LACH YEBU FGAR BOW LACH SAMO DMFN BLKI GOSH BLKI YEBU FGAR SNAK RESU GOSH YEBU BLCR FGAR MITE YEBU SPSU BRBU BLCR SPSU GSHR CRAY RESU RESU BRBU SPSU BOWLEKI BOW DRGN GSHR SPSU GOTO SPSU YEBU GSHR SPTI SPSUBRBU GOSH RESU GOSH DMFN HYAL GOSH GOSH BRBU GOSH GOSHGOSH GOSH GOSH BRBU BRBU BRBU BRBU BRBU BRBU BRBU 1.0 4.5 8.0 11.5 15.0 15 N ( l ) BETI Log THg (ng/g ww) 4 3 2 1 WCA3A 3A-15 WCA2A U3 / MGH WCA3A L-67 Canal WCA2A L-35 Canal ENR Outflow ENR Cell 3 WGYR FROG CRAY GOTO GSHR CRAY DRGN 0 BETI GAST 0 3 6 9 12 15 15 N (l ) CPIK GOSH BRBU BOW FGAR RPIK CPIK BOW SPSU BLCR BOW YEBU YEBU RESU MACI BOW MACI RPIK FGAR RESU YEBU SPSU SPSU SPSU RESU SPTI LACH WACA RESU GOTO GOSH GOTO GSHR GOSH GAFL LACHBLKI LEKI YEBU SEKI FGAR FGAR BLCR GRSH BOW BOW SAMO SNAK BLKI MITE BRBU RESU SPSU BRBU DMFN LEKI BRBU BOW GSHR GOTO SPTI HYAL Mean Whole-Body THg (µg/g) 2.0 1.5 1.0 0.5 Pearson Correlation Coefficient = 0.929 P < 0.005; n = 8 Spotted sunfish Redear sunfish Bluegill Bowfin Largemouth bass Warmouth Chain pickerel Florida gar 0.0 1.5 2.0 2.5 3.0 3.5 Trophic Score Isotopes and Food habits estimated trophic position show consistent positive relationships to biota THg Slopes not sig different Intercepts sig different
Variations in Trophic Position do not explain variations in bass THg 0.80 Trophic Class 4 3A15 Trophic Class 5 Whole-body THg (µg g -1 ) 0.60 0.40 0.20 L67A U3 L35B ENR 0.00 2.8 2.9 3.0 3.1 3.2 3.3 3.4 Trophic Score
Management of Mercury in the EPA Monitoring spatial and temporal trends in fish and wildlife mercury Support risk assessment for humans and piscivorous wildlife Means to evaluate influence of Everglades management Evidence suggests that variations in food web dynamics (complexity, length, and trophic position) are less influential than the availability of MeHg at the base of the food web Field studies suggest that methylation and bioaccumulation processes vary among Marsh Impoundments and are influenced by gradients of biogeochemical parameters (e.g. hydroperiod, Organic Carbon, Sulfate) This compartmentalization and complexity impedes development of concise empirical relationships between fish THg and environmental variables that influence MeHg production and bioaccumulation. Fish and Wildlife Hg will be reduced through Reductions in Deposition Managing for reductions in the rate of methylation