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Exploring the effects of temperature and resource limitation on mercury bioaccumulation in Fundulus heteroclitus using dynamic energy budget modeling and behavioral assessment
Citation:
Clark, B., K. Buckman, A. Bertrand, I. Kirby, J. Bishop, D. Champlin, C. Chen, AND D. Nacci. Exploring the effects of temperature and resource limitation on mercury bioaccumulation in Fundulus heteroclitus using dynamic energy budget modeling and behavioral assessment. International Conference on Mercury as a Global Pollutant, Providence, Rhode Island, July 16 - 21, 2017.
Impact/Purpose:
Presentation at the International Conference on Mercury as a Global Pollutant will allow me to interact with experts in the field and present our research regarding the integration of growth, bioaccumulation, and reproductive effects of mercury into an energetic modeling framework. The conference provides an opportunity to refine and improve the work through discussion with experts focused on mercury in the environment.
Description:
Global climate change is likely to affect both temperature and resource availability in aquatic ecosystems. While higher temperatures may result in increased food consumption and increased mercury accumulation, they may also lead to increased growth and reduced mercury accumulation through somatic dilution. Dynamic energy budget (DEB) theory provides a broad and generalizable framework based on first principles of energy metabolism that is well suited to understand these interactions, allowing joint acquisition and interpretation of chemical exposure and stressor effect information to be translated into demographic rate changes. In the current study, we conducted growth and bioaccumulation experiments to examine the interaction of temperature and resource availability on mercury accumulation and effects in the estuarine fish Fundulus heteroclitus (mummichog). In the first experiment, juvenile mummichog were fed tuna naturally contaminated with Hg at either 3.3% or 10% of their dry body weight/day and held at either 15 or 27 °C for 28 days. Growth was low in most treatments, except in fish fed 10% body weight held at 27 °C (40% weight and 12% length increase). However, methylmercury bioaccumulation was similar across feeding conditions but increased with temperature (~17-fold increase in methylmercury concentration at 27 °C and ~7-fold increase at 15 °C, regardless of feeding rate). In the second experiment, mummichogs from two wild populations with differing native mercury exposures were fed either a high or low methylmercury diet. Fish were strip-spawned every two weeks during the feeding period. Adults were sampled for total mercury concentration at the start and end of the experiment, and egg methylmercury concentration was measured in unfertilized eggs from each spawning event. Danioscope software was used to assess the heart rate of developing embryos at 10 days post fertilization. A dark:light movement assay determined differences in behavior of larvae between treatments at three and 10 days post hatch using Ethovision software. Tissue analysis indicated successful maternal transfer of mercury to eggs in the high mercury feed treatment. Heart rate and movement assays indicated potential population level differences in baseline behavior. The use of these data in a DEB model may greatly aid in understanding how temperature and resource availability affect mercury bioaccumulation. Overall, this work contributes to the ongoing development of an ecological modeling framework in a fish with an extensive toxicological and genomic background. Ultimately, we are working to connect molecular mechanistic, physiological, reproductive, and behavioral responses to population level fitness.