Brevetoxin exposure in sea turtles in south Texas (USA) during Karenia brevis red tide.

Five green (Chelonia mydas) and 11 Kemp's ridley (Lepidochelys kempii) sea turtles found dead, or that died soon after stranding, on the southern Texas (USA) coast during 2 Karenia brevis blooms (October 2015, September-October 2016) were tested for exposure to brevetoxins (PbTx). Tissues (liver, kidney) and digesta (stomach and intestinal contents) were analyzed by ELISA. Three green turtles found alive during the 2015 event and 2 Kemp's ridley turtles found alive during the 2016 event exhibited signs of PbTx exposure, including lethargy and/or convulsions of the head and neck. PbTx were detected in 1 or more tissues or digesta in all 16 stranded turtles. Detected PbTx concentrations ranged from 2 to >2000 ng g-1. Necropsy examination and results of PbTx analysis indicated that 10 of the Kemp's ridleys and 2 of the green turtles died from brevetoxicosis via ingestion. This is the first documentation of sea turtle mortality in Texas attributed to brevetoxicosis.

Analysis of diarrhetic shellfish poisoning toxins and pectenotoxin-2 in the bottlenose dolphin (Tursiops truncatus) by liquid chromatography-tandem mass spectrometry.

Toxins produced by harmful algae are associated with detrimental health effects and mass mortalities of marine mammals. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is generally used to confirm the presence of algal toxins in marine mammals. Sample preparation and LC-MS/MS methods for the determination of three diarrhetic shellfish poisoning (DSP) toxins (okadaic acid, OA; dinophysistoxin-1, DTX1; dinophysistoxin-2, DTX2) and pectenotoxin-2 (PTX2) in bottlenose dolphin (Tursiops truncatus) urine and tissue samples were evaluated using spike-and-recovery tests. Sample clean-up with either reversed-phase silica or polymeric solid-phase extraction (SPE) reduced interference of sample matrices and improved toxin recoveries, with polymeric SPE showing higher sample loading capacity. LC separation on Xbridge C18 columns using acetonitrile/water gradient elutions with ammonia as the additive was chosen for its high detectivity and sensitivity in the MS detection of DSP toxins in negative ion mode. The retention times of OA, DTX1, and DTX2, separated as negative ions, increased with LC column temperature while the retention time of PTX2, separated as the neutral molecule, was weakly affected. At the same column temperature, retention times of OA, DTX1, and DTX2 gradually increased as the mobile phases aged while the retention time of PTX2 remained unchanged; higher column temperatures resulted in a greater increase in the retention time of each DSP toxin with mobile phase aging. Average recoveries of the 4 toxins in bottlenose dolphin samples ranged from 80% to 130% with relative standard deviations of less than 15% using the LC mobile phases prepared within one week at a column temperature of 30°C or 40°C. The preferred column temperature was 30°C, as the retention times of DSP toxins were less affected by mobile phase aging at this temperature. The limit of detection of each toxin analyzed in bottlenose dolphin samples was 2.8 ng/g or less in tissue samples and 0.7 ng/ml or less in urine.

Forensic identification of seal oils using lipid profiles and statistical models.

Seal blubber oils are used as a source of omega-3 polyunsaturated fatty acids in Canada but prohibited in the United States and (FA) European Union. Thus, a reliable method is needed to identify oils originating from seals versus fish. Two lipid profiling methods, fatty acid analysis using gas chromatography and triacylglycerol (TAG) analysis using liquid chromatography and mass spectrometry, were applied with statistical models to discriminate commercial oils and blubber samples harvested from marine fish and seals. Significant differences were observed among FA profiles, and seal samples differed from each of the fish oils (p ≤ 0.001). FA and TAG profiles were used to discriminate sample groups using a random forest classifier; all samples were classified correctly as seals versus fish using both methods. We propose a two-step method for the accurate identification of seal oils, with preliminary identification based on FA profile analysis and confirmation with TAG profiles.