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Abstract. Here we present the first steps in developing a global multi-model aerosol forecasting ensemble intended for eventual operational and basic research use. Drawing

– Upstream passage of adult sea trout (Salmo trutta) in a nature‐like bypass channel was investigated in the Tirsbæk brook, Denmark, in autumn and winter 1999/2000. Sea trout were caught by electrofishing up‐ and downstream of the weir at which the bypass was situated. Fish were tagged with passive integrated transponder (PIT) tags and released downstream of the weir. Automatic PIT‐tag logging stations were positioned downstream, in the lower part, and at the upstream exit of the bypass to investigate the passage success of the fish. The bypass was neither size‐ nor sex‐selective in the size ranges investigated. The majority (68%) of fish approached the bypass at night. Over 90% of tagged upstream‐searching fish located and entered the bypass channel, but only about half of them passed through. The inefficiency is suggested to be because of a combination of the length of the bypass channel and inadequate flow in the bypass channel.

Abstract-Olfactory epithelial structure and olfactory bulb neurophysiological responses were measured in chinook salmon and rainbow trout in response to 25 to 300 g copper (Cu)/L. Using confocal laser scanning microscopy, the number of olfactory receptors was significantly reduced in chinook salmon exposed to Ն50 g Cu/L and in rainbow trout exposed to Ն200 g Cu/L for 1 h. The number of receptors was significantly reduced in both species following exposure to 25 g Cu/L for 4 h. Transmission electron microscopy of olfactory epithelial tissue indicated that the loss of receptors was from cellular necrosis. Olfactory bulb electroencephalogram (EEG) responses to 10 Ϫ3 M L-serine were initially reduced by all Cu concentrations but were virtually eliminated in chinook salmon exposed to Ն50 g Cu/L and in rainbow trout exposed to Ն200 g Cu/L within 1 h of exposure. Following Cu exposure, EEG response recovery rates were slower in fish exposed to higher Cu concentrations. The higher sensitivity of the chinook salmon olfactory system to Cu-induced histological damage and neurophysiological impairment parallels the relative species sensitivity observed in behavioral avoidance experiments. This difference in species sensitivity may reduce the survival and reproductive potential of chinook salmon compared with that of rainbow trout in Cu-contaminated waters.

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