An outbreak of food poisoning in Canada during autumn 1987 was traced to cultured blue mussels (Mytilus edulis) from the Cardigan Bay region of eastern Prince Edward Island (P.E.I.). The toxin, identified as domoic acid, had not previously been found in any shellfish and this outbreak represents the first known occurrence of human poisoning by this neurotoxin. A plankton bloom at the time of the outbreak consisted almost entirely of the pennate diatom, Nitzschia pungens f. multiseries, and a positive correlation was found between the number of N. pungens cells and the concentration of domoic acid in the plankton. Nitzschia pungens f. multiseries isolated from Cardigan Bay produced domoic acid in culture at levels (1 to 20 pg∙cell−1) comparable with values estimated for N. pungens in the plankton samples. Isolates of several Cardigan Bay phytoplankton, including the closely related species Nitzschia seriata, failed to produce domoic acid. Other Nitzschia spp. and two Amphora coffeaeformis isolates also failed to produce domoic acid. We conclude that N. pungens was the major source of the domoic acid in toxic mussels in eastern P.E.I. The recurrence, in November 1988, of a monospecific bloom of N. pungens and the presence of domoic acid in plankton and mussels reinforced this conclusion.

In contrast to mammalian therapeutics, the use of pharmaceutical substances is rather limited in fish. It is basically restricted to anaesthetic agents and anti-infective agents for parasitic and microbial diseases. Anaesthetic agents are used primarily in fish farm and laboratory settings to provide analgesia and immobilization of fish for minor procedures. The anti-infective agents are used for controlling diseases and the choice of drug depends on efficacy, ease of application, human safety, target animal safety including stress to the fish, environmental impact, regulatory approval, costs, and implications for marketing the fish. In this article, the major drugs used in salmonids in North America and Europe will be reviewed and some insight into future directions for drug development and use for the salmonid industry will be introduced. The mechanisms of action, pharmacokinetics, side effects, and uses of the drugs are emphasized.

Physiological, immunological and biochemical parameters of blood and mucus, as well as skin histology, were compared in 3 salmonid species (rainbow trout Oncorhynchus mykiss, Atlantic salmon Salmo salar and coho salmon O. kisutch) following experimental infection with sea lice Lepeophtheirus salmonis. The 3 salmonid species were cohabited in order to standardize initial infection conditions. Lice density was significantly reduced on coho salmon within 7 to 14 d, while lice persisted in higher numbers on rainbow trout and Atlantic salmon. Lice matured more slowly on coho salmon than on the other 2 species, and maturation was slightly slower on rainbow trout than on Atlantic salmon. Head kidney macrophages from infected Atlantic salmon had diminished respiratory burst and phagocytic capacity at 14 and 21 d post-infection (dpi), while infected rainbow trout macrophages had reduced respiratory burst and phagocytic capacities at 21 dpi, compared to controls. The slower development of lice, coupled with delayed suppression of immune parameters, suggests that rainbow trout are slightly more resistant to lice than Atlantic salmon. Infected rainbow trout and Atlantic salmon showed increases in mucus lysozyme activities at 1 dpi, which decreased over the rest of the study. Mucus lysozyme activities of infected rainbow trout, however, remained higher than controls over the entire period. Coho salmon lysozyme activities did not increase in infected fish until 21 dpi. Mucus alkaline phosphatase levels were also higher in infected Atlantic salmon compared to controls at 3 and 21 dpi. Low molecular weight (LMW) proteases increased in infected rainbow trout and Atlantic salmon between 14 and 21 dpi. Histological analysis of the outer epithelium revealed mucus cell hypertrophy in rainbow trout and Atlantic salmon following infection. Plasma cortisol, glucose, electrolyte and protein concentrations and hematocrit all remained within physiological limits for each species, with no differences occurring between infected and control fish. Our results demonstrate that significant differences in mucus biochemistry and numbers of L. salmonis occur between these species. KEY WORDS: Skin mucus · Lysozyme · Sea lice · Protease · Alkaline phosphatase · Salmonids · ImmunityResale or republication not permitted without written consent of the publisher

The isolation of infectious salmon anaemia virus (ISAV) from asymptomatic wild fish species including wild salmon, sea trout and eel established that wild fish can be a reservoir of ISAV for farmed Atlantic salmon. This report characterizes the biological properties of ISAV isolated from a disease outbreak in farmed Coho salmon in Chile and compares it with ISAV isolated from farmed Atlantic salmon in Canada and Europe. The virus that was isolated from Coho salmon tissues was initially detected with ISAV-specific RT-PCR (reverse transcription-polymerase chain reaction). The ability of the virus to grow in cell culture was poor, as cytopathology was not always conspicuous and isolation required passage in the presence of trypsin. Virus replication in cell culture was detected by RT-PCR and IFAT (indirect fluorescent antibody test), and the virus morphology was confirmed by positive staining electron microscopy. Further analysis of the Chilean virus revealed similarities to Canadian ISAV isolates in their ability to grow in the CHSE-214 cell line and in viral protein profile. Sequence analysis of genome segment 2, which encodes the viral RNA polymerase PB1, and segment 8, which encodes the nonstructural proteins NS1 and NS2, showed the Chilean virus to be very similar to Canadian strains of ISAV. This high sequence similarity of ISAV strains of geographically distinct origins illustrates the highly conserved nature of ISAV proteins PB1, NS1 and NS2 of ISAV. It is noteworthy that ISAV was associated with disease outbreaks in farmed Coho salmon in Chile without corresponding clinical disease in farmed Atlantic salmon. This outbreak, which produced high mortality in Coho salmon due to ISAV, is unique and may represent the introduction of the virus to a native wild fish population or a new strain of ISAV. KEY WORDS: ISAV in Coho salmon · ISAV morphology · Immunoprecipitation of ISAV proteins Resale or republication not permitted without written consent of the publisherDis Aquat Org 45: [9][10][11][12][13][14][15][16][17][18] 2001 associated, resulting in focalized infection of the cell monolayer and slow development of CPE. ISAV isolates from Norway and Scotland, similar to the second Canadian group (the CHSE-negative phenotype), do not produce CPE in the CHSE-214 cell line. However, there are significant nucleotide and amino acid sequence differences between the European and Canadian isolates on RNA segments 2 and 8 (Blake et al. 1999), and the European isolates could be differentiated from Canadian isolates by reverse transcriptionpolymerase chain reaction (RT-PCR) and restriction fragment length polymorphism (RFLP) on RNA segment 2 (Kibenge et al. 2000).The present study characterizes an orthomyxo-like virus isolated from farmed Coho salmon Oncorhynchus kisutch in Chile, with clinical disease. While erythrocytic inclusion body syndrome virus (EIBSV) was detected in one fish sample, the orthomyxo-like virus was found in several fish tissue pools from the affected farms. The virus was biologically chara...

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[1] Long-term elution tailing of organic contaminants, often observed when water or air is used to flush contaminated porous media, has been attributed to several factors. Characterization of this tailing behavior through the quantitative analysis of multiple coupled factors is necessary to enhance our understanding of contaminant transport. The objective of this study was to investigate the transport and elution behavior of trichloroethene in a naturally heterogeneous (poorly sorted) aquifer material, with a specific focus on characterizing and quantifying the relative contributions of rate-limited immiscible-liquid dissolution and nonlinear, rate-limited sorption/desorption to lowconcentration elution tailing. A comparison of trichloroethene elution behavior for systems with and without immiscible-liquid phase present suggests that the lowconcentration elution tailing observed in the former experiments is associated primarily with nonlinear, rate-limited sorption/desorption. The transport and elution of trichloroethene was successfully simulated using a mathematical model that combines independent, coupled descriptions of rate-limited dissolution and nonlinear, rate-limited sorption/desorption. Specifically, immiscible-liquid dissolution was described using a first-order mass transfer approach with a temporally variable dissolution rate coefficient, and sorption/desorption was described using an approach incorporating a continuous distribution of rate-limited domains. The results of this study indicate that multiple processes contributed to trichloroethene elution behavior when immiscible-liquid phase was present and that a multiprocess model was required to accurately simulate the measured data.

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