Department of Chemistry and Biochemistry, Coastlines and Oceans Division, Institute of Environment, Florida International University, 3000 NE 151st Street, North Miami, FL, 33181, USA.
Dolphins Plus, 101900 Overseas Highway, Key Largo, FL, 33037, USA.
Chemosphere. 2022 Feb;288(Pt 1):132423. doi: 10.1016/j.chemosphere.2021.132423. Epub 2021 Sep 29.
Intoxications of captive bottlenose dolphins (Tursiops truncatus) in the Florida Keys have been linked to observed interactions with marine macrophytic algal and cyanobacterial communities within enclosures. Taxonomic characterization of these communities coupled, in turn, to available observational data collected during intoxication events point to a contribution of filamentous cyanobacterial assemblages comprised of members of the polyphyletic genus, Lyngbya sensu lato. To identify toxic metabolites possibly relevant to these intoxications, chemical screening for known neurotoxins from cyanobacteria, as well as other regionally relevant harmful algal bloom (HAB) taxa, was combined with toxicity testing, and subsequent bioassay-guided fractionation, employing early life stages (i.e., embryos and larvae) of zebrafish (Danio rerio) as a well-established aquatic vertebrate toxicological model. Chemical analyses did not detect (within analytical limits) any of the known algal or cyanobacterial neurotoxins. Toxicity testing, alongside bioassay-guided fractionation, however, identified several chemical fractions with a range of potentially relevant bioactivities in both zebrafish embryos and post-hatch larvae including, in particular, behavioral (e.g., aberrant swimming) and physiological (e.g., altered heart rate) endpoints indicative of possible neurotoxicity, and subsequent chemical characterization of fractions suggested a contribution of the previously identified bioactive metabolite, eudesmacarbonate, in the observed toxicity. Comparative toxicological assessment with PbTx-2, as a positive control for neurotoxicity in the zebrafish model, further supported neurotoxic activity of cyanobacterial metabolites potentially relevant, in turn, to a contribution of these metabolites to dolphin intoxications. These findings suggest, in general, that marine zoological facilities may be affected by regional HABs, and assessments of potentially toxigenic algae and cyanobacteria should be included in management strategies in these facilities.
佛罗里达群岛的圈养宽吻海豚（Tursiops truncatus）中毒与圈养中观察到的与海洋大型藻类和蓝藻群落的相互作用有关。这些群落的分类特征，再加上在中毒事件中收集的可用观察数据，表明丝状蓝藻组合的贡献，其中包括多系属 Lyngbya sensu lato 的成员。为了确定可能与这些中毒有关的有毒代谢物，对蓝藻中的已知神经毒素以及其他区域相关的有害藻华（HAB）分类群进行了化学筛选，同时进行了毒性测试以及随后的基于生物测定的馏分分离，采用早期生命阶段（即胚胎和幼虫）斑马鱼（Danio rerio）作为一种成熟的水生脊椎动物毒理学模型。化学分析未检测到（在分析极限内）任何已知的藻类或蓝藻神经毒素。然而，毒性测试以及基于生物测定的馏分分离鉴定了几种具有多种潜在相关生物活性的化学馏分，包括斑马鱼胚胎和孵化后幼虫的一系列潜在相关生物活性，特别是行为（例如，异常游泳）和生理（例如，心率改变）终点表明可能存在神经毒性，随后对馏分的化学特征分析表明，先前鉴定的生物活性代谢物 eudesmacarbonate 对观察到的毒性有贡献。用 PbTx-2 进行比较毒理学评估，作为斑马鱼模型中神经毒性的阳性对照，进一步支持了蓝藻代谢物的神经毒性活性，这些代谢物反过来又可能对海豚中毒有贡献。这些发现表明，一般来说，海洋动物园可能会受到区域 HAB 的影响，并且应该在这些设施的管理策略中包括对潜在产毒藻类和蓝藻的评估。
