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Variability of Mercury Concentrations in Fishwith Season, Year, and Body ConditionA Synthesis of the Literatureand Considerations for Advisory Programs: 

Variability of Mercury Concentrations in Fish with Season, Year, and Body Condition A Synthesis of the Literature and Considerations for Advisory Programs 2005 National Forum on Contaminants in Fish September 18-21, 2005 Baltimore Marriott Inner Harbor, Baltimore MD Paul Cocca Office of Science and Technology Office of Water US EPA

Overview: 

Overview Seasonal and interannual variability of fish mercury concentrations is significant Caused primarily by fluctuations in fish growth and nutrition Ideas for advisory programs to consider

Measured Seasonality in Fish Hg: 

Measured Seasonality in Fish Hg Whitemouth croaker in Brazilian estuaries (Kehrig et al, 1998) Explanatory hypotheses: Concentrations increase when fish lose weight Spring bioproduction dilutes the available mercury micropogonias furnieri whitemouth croaker * All concentrations normalized to 700 g fish, wet wt.

Measured Seasonality in Fish Hg: 

Measured Seasonality in Fish Hg Perch in the southern Baltic Sea (Szefer et al, 2003) concentrations not normalized Perca fluviatilis European Perch Seasonal differences supported through factor analysis

Measured Interannual Variability in Fish Hg: 

Striped bass in San Francisco Bay (Greenfield et al, 2005) 1997 statistically different from other years Explanatory hypotheses (Greenfield et al, 2005): Higher Hg bioavailability from 1997 flood event Different populations exposed to different MeHg concentrations Variability in movement patterns or diets Measured Interannual Variability in Fish Hg

Measured Interannual Variability in Fish Hg: 

Largemouth bass in Oregon reservoirs (Park & Curtis, 1997) Explanatory hypotheses Environmental conditions influence MeHg production, bioavailability Concentration decreases caused by growth dilution Cottage Grove Reservoir, OR Fig. 6 Park and Curtis, 1997 1993 1994 1995 Measured Interannual Variability in Fish Hg Micropterus salmonides Largemouth Bass

Measured Interannual Variability in Fish Hg: 

Measured Interannual Variability in Fish Hg Yellow perch yearlings in 16 Ontario lakes, whole fish, unadjusted (Suns and Hitchin 1990) Monitored over 10 year period, ~7 sampling events per lake High concentration : Low concentration ratio ranges from 1.5 to 2.2 for most lakes

A Partial Cause: Depuration LossDuring Reduced Hg Bioavailability: 

A Partial Cause: Depuration Loss During Reduced Hg Bioavailability Fish MeHg depuration half-lives (Huckabee et al, 1979) Northern pike: 100 days Bullheads: 178 – 277 days Ling: 433 – 707 days Rainbow trout: 1000 days Central tendency: 300 days Depuration may account for some literature reported variability Were depuration fast, fish MeHg would mirror ambient levels Instead MeHg depuration is slow which dampens variability

More Important: Variable Fish Nutrition : 

More Important: Variable Fish Nutrition Fish Hg levels decrease during Growth Dilution Negative correlation with growth rate (r2 = 0.92) (Simoneau et al, 2005) Higher concentrations in dwarf than normal fish (Doyon, et al 1998) Faster growth reflects efficiency; flesh added with proportionally less food and mercury intake (Greenfield et al, 2001) Fish Hg levels increase during Starvation Concentration Higher concentrations in skinny than robust fish (Hinners, 2004; Cizdziel et al., 2002 & 2003) Starved, non-starved lose MeHg same rate (Burrows & Krenkel, 1973) Starving fish can lose muscle quicker than mercury

Fish Body Condition: 

Fish Body Condition How to quantify fish body condition Condition Factor, K (Williams, 2000) W/L3 x 100; where W is weight (g) L is the standard length (cm) Results in an index value close to 1 Online calculator: http://www.hac.org.nz/cf.htm What the condition factor measures Relative robustness, degree of well-being, nutritional status Reflects both seasonal and longer term nutritional trends Potentials for growth dilution and starvation concentration Brown trout, K Factor: 0.78 Brown trout, K Factor: 1.66 from: Barnham & Baxter 1998

Measured Variability with Fish Body Condition: 

Fish Hg negatively correlates with condition factor Striped bass (r2 = 0.79) (Hinners 2004; Cizdziel et al. 2003) Yellow perch yearlings (r2 = 0.66) (Suns and Hitchin 1990) whole fish composites Yellow perch (r2 = .35) (Greenfield et al. 2001) whole fish Measured Variability with Fish Body Condition

Body Condition: Cause or Effect?: 

Body Condition: Cause or Effect? Body Condition Affects Hg Levels Condition varies by factor 1.4 - 1.7 (Lizama et al 2002) Hg Levels Affect Body Condition Less protein synthesis enzymes at higher Hg levels (Nicholls et al 1987; Suns & Hitchin 1990)

Summary of the Literature: 

Summary of the Literature Seasonal and interannual variability is significant High concentration : Low concentration = 1.5 to 2.0 Higher concentrations in colder months Higher concentrations in skinnier fish Mercury depuration is too slow to explain all variability Variable body condition affects fish mercury Growth Dilution Starvation Concentration

Considerations for Advisory ProgramsMonitoring Design and Data Analysis: 

Considerations for Advisory Programs Monitoring Design and Data Analysis Measure weight as well as length => condition factor Measure age as well as length => growth rate Correlations: length, weight, age, growth rate, condition Regressions on a sampling event basis Always sample the same season Conversely, sample all seasons and: Normalize concentrations to a standard season Develop seasonality safety factors Sample enough to estimate long-term means and variances

Considerations for Advisory ProgramsAdvisory messages, etc.: 

Considerations for Advisory Programs Advisory messages, etc. Include seasons in advisories (e.g. “special note to ice fishers”) Include condition in advisories (e.g. “skinny bad, fat good”) Use condition factor as an inexpensive Hg index Promote fisheries health to reduce human exposure

Acknowledgements: 

Acknowledgements Tom Hinners, US EPA, Las Vegas Ben Greenfield and Larry Curtis for permission to use figures from cited works Fish pictures from http://www.fishbase.org

References: 

References Barnham and Baxter, 1998. Fisheries Notes: Condition Factor, K, for Salmonid Fish. State of Victoria, Department of Primary Industries. ISSN 1440-2254. Burrows and Krenkel, 1973. Studies on Uptake and Loss of Methylmercury-203 by Bluegills (Lepomis marcochirus Raf.). ES&T vol. 7, No. 13, 1127-1130. Cizdziel, J.V., T.A. Hinners, J.E. Pollard, E.M. Heithmar, and C.L. Cross. 2002. Mercury concentrations in fish from Lake Mead, USA, related to fish size, condition, trophic level, location, and consumption risk. Arch. Environ. Contam. Toxicol. 43: 309-317. Cizdziel, J.V., T.A. Hinners, C.L. Cross, and J.E. Pollard. Distribution of mercury in the tissues of five species of freshwater fish from Lake Mead, USA. 2003. J. Environ. Monit. 5: 802-807. Doyon, J.F., R. Schentagne, and R. Verdon, 1998. Different mercury bioaccumulation rates between sympatric populations of dwarf and normal lake whitefish (Coregonus clupeaformis) in the La Grande complex watershed, James Bay, Quebec. Biogeochemistry 40: 203-216, 1998. Foster, Drake, and DiDomenico, 2000. Seasonal Changes and Tissue Distribution of Mercury in Largemouth Bass (Micropterus salmoides) from Dorena Reservoir, Oregon. Contamination and Toxicology. Fulton, T. 1902. Rate of growth of seas fishes. Sci. Invest. Fish, Div. Scot. Reprt, 20. Giblin and Massaro, 1973. Pharmacodynamics of methylmercury in the rainbow trout (Salmo gairdneri): Tissue uptake, distribution and excretion. Toxicology and Applied Pharmacology. Volume 24, Issue 1, January 1973, Pages 81-91. Greenfield, B.K., T.R. Hrabik, C.J. Harvey, and S.R. Carpenter, 2001. Predicting mercury levels in yellow perch: use of water chemistry, trophic ecology, and spatial traits. Can. J. Fish. Aquat. Sci. 58: 1419-1429 (2001). Greenfield, B.K., J.A. Davis, R.Fairey, C. Roberts, D. Crane, and G. Ichikawa, 2005. Seasonal, interannual, and long-term variation in sport fish contamination, San Francisco Bay. Science of the Total Environment 336(2005) 25-43. Hinners, T.A. 2004. Possible ramifications of higher mercury concentrations in fillet tissue of skinnier fish. 2004 National Forum on Contaminants in Fish, San Diego, California, January 25-28. Huckabee, J.W., J.W. Elwood, and S.G. Hildebrand, 1979. Accumulation of mercury in freshwater biota. Nriagu (ed.) The biogeochemistry of mercury in the environment. Elsevier/North-Holland Biomedical Press 1979. Kehrig, Malm, and Moreira, 1998. Mercury in a widely consumed fish Micropogonias furnieri (Demarest, 1823) from four main Brazilian estuaries. The Science of the Total Environment 213 (1998) 263-271. Lizama, M. Delos A.P. and Ambrosio, A..M. Condition factor in nine species of fish of the Characidae family in the upper Paraná River floodplain, Brazil. Braz. J. Biol., Feb. 2002, vol.62, no.1, p.113-124. ISSN 1519-6984. McKim, J.M., G.F. Olson, G.W. Holcombe, and EP. Hunt, 1976. Long-tem effects of methylmercuric chloride on three generations of brook trout (Salvelinus fontinalis): toxicity, accumulation, distribution, and elimination. J. Fish. Res. Board Can. 33: 2726-2739. Nicholls, Angelow, and Teichert-Kuliszewski, 1987. Effects on the Tissue of Young Fish and Rats of Exposure to Lead, Cadmium and Mercury, Report to the Ontario Ministry of the Environment. Park, J.-G. and L. R. Curis, 1997. Mercury Distribution in Sediments and Bioaccumulation by Fish in Two Oregon Reservoirs: Point-Source and Nonpoint-Source Impacted Systems. Arch. Environ. Contam. Toxicol. 33, 423-429 (1997). Rodgers, D.W., and F.W.H. Beamish, 1982. Dynamics of Dietary Methylmercury in Rainbow Trout, Salmo Gairdneri. Aquatic toxicology, 2 (1982) 271-290. Simoneau, M., M. Lucotte, S. Garceau, D. Laliberte, 2004. Fish growth rates modulate mercury concentrations in walleye (Sander vitreus) from eastern Canadian lakes. Environmental Research 98: 73-82. Suns, K., and Hitchin, G. 1990. Interrelationships between mercury levels in yearling yellow perch, fish condition and water quality. Water Air Soil Pollut. 650: 255-265. Szefer, P., M. Domaga-a-Wieloszewska, J. Warzocha, A. Garbacik-Weso-owska, and T. Ciesielski, 2003. Distribution and relationships of mercury, lead, cadmium, copper and zinc in perch (Perca fluviatilis) from the Pomeranian Bay and Szczecin Lagoon, southern Baltic. Food Chemistry. Volume 81, Issue 1, May 2003, Pages 73-83. Williams, J.E., 2000. The Coefficient of Condition of Fish. Chapter 13 in Schneider, James C. (ed.) 2000. Manual of fisheries survey methods II: with periodic updates. Michigan Department of Natural Resources, fisheries Special Report 25, Ann Arbor. Downloaded from: http://www.michigandnr.com/PUBLICATIONS/PDFS/ifr/manual/SMII%20Chapter13.pdf.