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Harmful algal blooms (HABs) in coastal British Columbia (BC), Canada, negatively impact the salmon aquaculture industry. One disease of interest to salmon aquaculture is Net Pen Liver Disease (NPLD), which induces severe liver damage and is believed to be caused by the exposure to microcystins (MCs). To address the lack of information about algal toxins in BC marine environments and the risk they pose, this study investigated the presence of MCs and other toxins at aquaculture sites. Sampling was carried out using discrete water samples and Solid Phase Adsorption Toxin Tracking (SPATT) samplers from 2017–2019. All 283 SPATT samples and all 81 water samples tested positive for MCs. Testing for okadaic acid (OA) and domoic acid (DA) occurred in 66 and 43 samples, respectively, and all samples were positive for the toxin tested. Testing for dinophysistoxin-1 (DTX-1) (20 samples), pectenotoxin-2 (PTX-2) (20 samples), and yessotoxin (YTX) (17 samples) revealed that all samples were positive for the tested toxins. This study revealed the presence of multiple co-occurring toxins in BC's coastal waters and the levels detected in this study were below the regulatory limits for health and recreational use. This study expands our limited knowledge of algal toxins in coastal BC and shows that further studies are needed to understand the risks they pose to marine fisheries and ecosystems. [ABSTRACT FROM AUTHOR]

The commercial chemotherapeutant formulations SLICE® and Alpha Max® [active ingredients emamectin benzoate ( EB) and deltamethrin respectively] are used in fin fish aquaculture to control parasitic sea lice. In some regions, the use of these substances has drawn concern from the commercial fishing industry regarding potential adverse effects on non-target organisms. In the present work, biodegradation of EB and deltamethrin, and their commercial formulations, was investigated over 135 days at 4 and 10°C in fresh marine sediments collected from underneath an active open net-pen salmon farm. EB incubated as either pure substance or commercial formulation was recalcitrant at both temperatures under abiotic and biotic conditions. Deltamethrin incubated alone or as its commercial formulation degraded slowly at 10°C ( t1/2 = 330 ± 107 and 201 ± 27.1 days respectively). At 4°C, deltamethrin degradation was only significant following incubation as commercial formulation ( t1/2 = 285 ±112 days). Degradation rates of EB and deltamethrin as pure substances versus their commercial formulations were not statistically different. Depletion of deltamethrin was observed in 10°C inactive sediments indicating that transformation occurred (at least in part) via an abiotic pathway. Overall, these data provide further insight into the fate and persistence of EB from the ongoing use of SLICE® in British Columbia's salmon aquaculture industry. AlphaMax® is not registered in Canada but is used in other salmon farming countries to control sea lice. [ABSTRACT FROM AUTHOR]

Two of the most common products currently used to control parasitic sea lice in fin fish aquaculture, salmon in particular, are Slice® and AlphaMax®. Emamectin benzoate (EB) is the active ingredient in Slice® and deltamethrin is the active ingredient in AlphaMax®. Several analytical methods have been developed for the determination of the active ingredients in these products but these have been focused on specific matrices and lack the sensitivity and versatility required in environmental monitoring. Here we present a validated, versatile, and simple analytical method for the determination of EB, its desmethyl degradation product (AB), and deltamethrin in a wide range of environmental matrices (sea water, marine sediment, and tissue). Sediments and tissues were extracted by accelerated solvent extraction (ASE®) and sample cleanup was achieved by solid phase extraction (SPE) while sea water was extracted using SPE disks. Analyte identification and quantification was based on liquid chromatography tandem mass spectrometry (LC-MS/MS) instrumentation with electrospray ionization, and multiple reaction monitoring (MRM). Method detection limits for the target analytes was in the parts per trillion (pg g−1) level for tissue and sediment and parts per quadrillion (pg L−1) for water. Except for deltamethrin in sea water, method performance in terms of analyte recoveries was better than 60%, and the method precision was RSD<20%. The method was used to determine EB and AB concentrations in water, sediment and prawn tissue samples collected near salmon aquaculture sites treated with Slice®. A distinct concentration gradient was observed in the immediate vicinity (within 50 to 100 m radius) of the salmon aquaculture sites where EB was detected at low ng g−1levels for tissue (EB ranged from 0.041 to 3.0 ng g−1) and sediment (EB ranged from 0.051 to 35 ng g−1) and pg L−1levels (EB ranged from 3 to 209 pg L−1) for water samples. [ABSTRACT FROM AUTHOR]