[en] Ecological studies continue to focus on the determination of the effects of energy-related pollutants on planktonic species typical of the Great Lakes. Also included were experimental studies of the effects of enclosure size on the response of zooplankton to stress by cadmium. A new mobile field laboratory was constructed to support studies of the effects of water temperatures regimes on rates of accumulation by salmonid fishes of persistent organic contaminants such as PCB's. A significant new addition to the Great Lakes Research Program was marked by the arrival and formal acceptance of the new research vessel, the R/V Ekos. Descriptions of the Ekos and its research capabilities are included. A variety of studies of the behavior of transuranic elements conducted in environments as diverse as the Irish Sea, Great Slave Lake, the Great Miami River, and the Great Lakes, have focused on changes in the oxidation state of plutonium, and the effects these changes have on the behavior of this important element in the aquatic environment. Twenty-six sections of the report were abstracted and indexed individually for inclusion on ERA/EDB and those in scope for INIS