The static acute toxicities of alpha-endosulfan, beta-endosulfan, (alpha + beta)-endosulfan, endosulfan sulfate (their transformation product), and formulated materials were determined for a representative freshwater amphipod (Hyalella azteca), cladoceran (Daphnia magna), and salmonid fish (Oncorhynchus mykiss). Acute lethality tests also were conducted on these organisms and coho salmon (Oncorhynchus kisutch) by exposing them to simulated field water endosulfan concentrations, using either a single compound and/or in combinations. As well, growth/survival bioassays of H. azteca were carried out in simulated sediment endosulfan concentrations that were detected in farm ditches contiguous to fish streams in the Lower Fraser Valley (BC, Canada). All materials tested were very highly toxic to these nontarget aquatic indicator organisms. As the most potent compound, alpha-endosulfan is about 1.3, 6.6, and 58 times more toxic than the beta-isomer to Daphnia, rainbow trout, and Hyalella, respectively. Some possible biological and toxicological implications of our findings are discussed in the context of endosulfan concentrations found in farm ditches flowing to fish streams in the Lower Fraser Valley.

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Low sulfur marine diesel (LSMD) is frequently involved in coastal spills and monitoring ecosystem damage, and the effectiveness of cleanup methods remains a challenge. The present study investigates the concentration and composition of polycyclic aromatic hydrocarbons (PAHs) dispersed in LSMD seawater accommodated fractions (WAFs) and assesses the effects of exposure on juvenile coho salmon (Onchorhynchus kisutch). Three WAFs were prepared with 333, 1067, and 3333 mg/L LSMD. The sum of 50 common PAHs and alkylated PAHs (tPAH50) measured by gas chromatography/triple quadrupole mass spectrometry showed saturation at ∼90 mg/L for all WAFs. These WAFs were diluted 30% for 96 h fish exposures. qPCR was performed on liver and caudal fin from the same genotypically sexed individuals to evaluate PAH exposure, general and oxidative stress, estrogenic activity, and defense against metals. Excluding metal response, our analyses reveal significant changes in gene expression following WAF exposure on juvenile salmon with differential sensitivity between males and females. The 3-methylcholanthrene responsive cytochrome P450-1a (cyp1a) transcript exhibited the greatest increase in transcript abundance in the caudal fin (10− 18-fold) and liver (6−10-fold). This demonstrates that cyp1a is a robust, sex-independent bioindicator of oil exposure in caudal fin, a tissue that is amenable to nonlethal sampling.

Emamectin benzoate is one of the active ingredients of the anti-sealice drug SLICE. Ten-day acute sediment lethal tests (10-d LC50) of emamectin benzoate and its desmethyl metabolite (AB1) were conducted to determine LC50 values using a sensitive representative West Coast amphipod crustacean, Eohaustorius estuarius. The 10-d LC50s of emamectin benzoate and AB1 to E. estuarius were 0.185 and 0.019 mg/kg wet weight sediment (0.146 and 0.015 mg/kg dry wt), respectively. The degradation properties of emamectin benzoate and AB1 during the 10-d period were also measured and described. No obvious decay patterns were observed for either emamectin benzoate and AB1 over the 10-d period.