Reproductive, Developmental, and Neurobehavioral Effects of Methylmercury in Fishes

Abstract

In the decades since the Minamata tragedy in Japan, there has been a considerable body of research performed on effects of methylmercury in fishes. The studies have revealed that some of the most sensitive responses seen in fishes are reminiscent of the symptoms experienced by the Minamata victims. This article reviews the literature, with a focus on mercury's effects on fish reproduction (hormone levels, gametogenesis, fertilization success), embryonic development (morphological abnormalities, rate), the development of behavior, and neurobehavioral effects in adults. Both experimental exposures and epidemiological approaches are included. There have been many studies demonstrating delayed effects of mercury exposure in that exposures during one life history stage can produce effects much later during different life history stages. For example, exposure of maturing gametes can result in abnormal embryos, even though the embryos were not themselves exposed to the toxicant. Exposures during sensitive embryonic periods can produce long-lasting effects that can be seen in adult stages. The existence of these manifold delayed effects renders the practice of short-term toxicity testing particularly unhelpful for understanding the effects of this (and other) toxicants.

Key Words:

• mercury
• fish
• behavior
• embryo
• larva

ACKNOWLEDGEMENTS

I thank Dr. Peddrick Weis for his collaboration, insights, and analytical skills over the years of studying mercury and fish. I appreciate the hard work of the many former graduate students in my laboratory who have helped to unravel effects of mercury on killifish and the adaptations and responses in our local polluted estuaries: Margarete Heber, Swati Toppin, Abu Khan, Anwar Khan, Graeme Smith, Tong Zhou, Jennifer Samson, and Celine Santiago Bass. We appreciate funding from the NJ Sea Grant Program, NOAA, USGS Water Resources Research Institute, USEPA, and NJ DEP. I thank Tim Kubiak for inviting me to participate in the SETAC symposium.

This paper was developed from a presentation given at the symposium on “Common Effects Endpoints for Persistent Toxic Substances in Human and Ecological Epidemiology” at the 2007 Society of Environmental Toxicology and Chemistry (SETAC) annual meeting.