MERCURY BIOMAGNIFICATION IN SUBTROPICAL RESERVOIRS OF EASTERN CHINA by Neguysa Roxanna Razavi A thesis submitted to the Department of Biology In conformity with the requirements for the Degree of Doctor of Philosophy Queen’s University Kingston, Ontario, Canada June, 2014 Copyright © Neguysa Roxanna Razavi, 2014 Abstract Mercury (Hg) is a global pollutant, yet Hg biomagnification, the increase in Hg with trophic level, remains poorly characterized in many regions, especially at subtropical latitudes. The present study assessed subtropical reservoirs of eastern China, which provided an opportunity to quantify Hg biomagnification under highly altered conditions that included high atmospheric Hg deposition, use of reservoirs for fisheries, manipulation of food webs through stocking and high fishing pressure, and increasing eutrophication. Despite China’s Hg emission and deposition rates that are among the highest worldwide, low fish Hg concentrations and Hg biomagnification rates were found; this was explained by food web structure and fish species characteristics. Stocked species occupied lower trophic levels and had significantly lower Hg concentrations relative to wild fishes. Evidence of decreased Hg concentrations with eutrophication (as indicated by chlorophyll-a) was observed, suggesting algal biodilution and/or somatic growth dilution. Relative to temperate lakes, zooplankton density dilution may also be causing reduced Hg concentrations in subtropical biota. Hydrogeomorphic features, such as water retention time and percent crop cover, explained Hg bioaccumulation factors and Hg concentrations at the base of the food web. Eutrophication and hydrogeomorphic features also influenced the bioavailability of selenium, which can protect against the toxicity of Hg at adequate concentrations, and the concentration of eicosapentaenoic acid, a beneficial fatty acid, in the planktivorous Bighead Carp (Hypophthalmichthys nobilis). This may indicate that the risk of exposure to the neurotoxicant methylmercury relative to benefits of fish consumption may increase with eutrophication in some fish species. i Overall, the findings of this study suggest food web structure, eutrophication, and hydrogeomorphic features together explain low Hg concentrations in anthropogenically modified subtropical reservoirs in eastern China. ii Co-Authorship This thesis conforms to the Manuscript Format outlined by the School of Graduate Studies and Research, with consolidated Acknowledgements and Literature Cited sections. Dr. Linda M. Campbell (Queen’s University, Saint Mary’s University) and Dr. Yuxiang Wang (Queen’s University) co-authored all manuscripts, and were critical to project development, providing financial and logistical means for field work, and feedback at all stages of manuscript preparation. Mingzhi Qu (Queen’s University) co-authored all manuscripts, as he was key to providing access to the reservoirs and field assistance in China, as well as acquiring essential background data from the Chinese literature. Dr. Yang Zhong (Fudan University) co-authored Chapter 3 and Dr. Wenwei Ren (Tongji University) co-authored all manuscripts for providing contacts, lab space and field assistants, and for facilitating sample transport and stays in China. Dr. Jin Binsong (Nanchang University) co-authored Chapters 2 and 4, for his assistance in field sampling and fish species identification. Dr. Dongmei Chen (Queen’s University) co-authored Chapter 3 for her work on land use cover mapping. Dr. Michael Arts co-authored Chapter 4 for supporting fatty acid analyses and providing critical feedback on the manuscript. Manuscripts arising directly from this thesis: Razavi NR, Qu M, Jin B, Ren W, Wang Y, Campbell LM (2014) Mercury biomagnification in subtropical reservoir fishes of eastern China. Ecotoxicology 23:133–146 doi: 10.1007/s10646-013-1158-6 iii Razavi NR, Qu M, Chen D, Zhong Y, Ren W, Wang Y, Campbell LM (in review) Effect of eutrophication on mercury (Hg) dynamics in subtropical reservoirs from a high Hg deposition ecoregion. Razavi NR, Arts MT, Qu M, Jin B, Ren W, Wang Y, Campbell LM (in review) Effect of eutrophication on mercury, selenium, and essential fatty acids in Bighead Carp (Hypophthalmichthys nobilis) from reservoirs of eastern China. iv Acknowledgements I would like to express my great appreciation to Linda Campbell and Yuxiang Wang for their co-supervision of my work. I thank Linda for selecting me to take on this challenging project, for providing funding and supporting scholarships, grant applications, and attendance to workshops, national and international conferences, and most of all for helping me build my autonomy as a researcher. I thank Yuxiang for sharing his network of colleagues, which was essential to the success of this work in China, and I also thank him for his constant encouragement and availability to discuss and advise on various situations. I am grateful to both Linda and Yuxiang for their time and comments on my written work. My sincerest thanks are also extended to Peter Hodson for serving as my internal committee member, and whose advice, critical questions, and rigorous editing were crucial to the integrity of this work. I would also like to thank my examining committee consisting of Louise Winn, Dan Lefebvre, Peter Boag, and Alan Mak from Queen’s University for their time and feedback on the preparation of the final document. I am also very grateful to Marc Amyot at the Université de Montréal for accepting to serve as my external examiner. This project would not have been possible without the help of many colleagues in China. I express my gratitude to Ren Wenwei, Zhong Yang and Zhang Zhiyao for facilitating my travel and stays in China, as well as providing access to field assistants and lab space while at Fudan University. Qu Mingzhi and Chen Yanping were critical to completing fieldwork and communicating on my behalf while in China, I remain deeply humbled by their help and generosity. I am indebted to Jin Binsong for his field v assistance and instructions on Chinese fish species identification. I would also like to thank members of the local administration offices for granting access to reservoirs and providing assistance in the field. I am deeply appreciative of the feedback, advice and discussions from project development to manuscript preparation first and foremost from Raphaël Lavoie. Leonardo Campagna, David Depew, David Lean, Jeff Ridal and Brian Hickey were also of great assistance in this regard. Data acquisition was made possible by the work of many. Completion of mercury analyses would not have been feasible without the patient training and advice from Diana Babi at Tekran Instruments. Likewise, Emmanuel Yumvihoze at the University of Ottawa provided insights and instructions, and I would especially like to thank him for the analyses of methylmercury in water, zooplankton and Bighead Carp, as well as fielding many QA/QC questions. Thank you to Alexandre Poulain at the University of Ottawa for allowing me to complete my analyses under Emmanuel’s guidance. A sincere thank you to Mo Aomei and John Poulopoulos at Queen’s University for assistance with mercury analyses early on in this project. I would like to acknowledge and thank Allison Rutter, Graham Cairns and Mesha Thompson at the Queen’s Analytical Services Unit for selenium and preliminary methylmercury analyses. The sampling and analyses of tissues for fatty acids were possible by the generous help and guidance of Michael Arts, Jerry Chao, and Ashley Kling, then at the Canadian Centre for Inland Waters at Environment Canada. Further thanks to Michael Arts for feedback during manuscript preparation. I would like to express my gratitude to Pat Chow-Fraser and Maja Cvetkovic at McMaster vi University for the analyses of chlorophyll-a. I would also like to thank the Stable Isotope Facility at the University of California at Davis for always accommodating my timelines in the analyses of stable isotopes, and I thank Joy Matthews for answering questions regarding sample preparation. I would like express my gratitude to John Casselman at Queen’s for his work on fish ageing and for providing me with access to his laboratory, and technician Tom Hawson for extraction and preparation of otoliths. Thank you also to Courtney Holden for facilitating this aspect of my project. Thank you to Anneli Jokela and Kimberley Lemmen at Queen’s for assistance in zooplankton enumeration, and Jiming Fang at the Institute for Clinical Evaluative Sciences for his assistance with statistical analyses. I am very appreciative of Dongmei Chen at Queen’s for her acceptance to assist in reservoir land use characterization. Lastly, to the SWEP students Diana Flood, Victoria Donovan, Michele Parisien, and Kira MacDougall for their hard work in sample organization and preparation. I am greatly indebted to Biology and Environmental Studies staff for assistance with administrative work involved with travel, conference attendance, sample export, licensing, stipend provision and organizing committee meetings. For this I owe many thanks to Karen Topping, Karen Depew, Joanne Surette, Janice Gruenberg, Carol Noel, John Topping, Ruth Lappan, Ron Kerr and Tice Post. My labmates have provided support in the field and lab, critical feedback on manuscripts and many talks, and most importantly, their friendship and worldview. To Qu Mingzhi, Raphaël Lavoie, Christopher Baird, David Depew, John Poulopoulos, Mark Kelly, Marina Arcagni, Zhang Liang, Sae Yun Kwon, Fang Tian and Elizabeth Yanch.