CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China.
Fisheries College, Ocean University of China, Qingdao 266003, China.
Sci Total Environ. 2021 Aug 1;780:146484. doi: 10.1016/j.scitotenv.2021.146484. Epub 2021 Mar 17.
The dinoflagellate genus Alexandrium has been well known for causing paralytic shellfish poisoning (PSP) worldwide. Several non-PSP toxin-producing species, however, have shown to exhibit fish-killing toxicity. Here, we report the allelopathic activity of Alexandrium leei from Malaysia to other algal species, and its toxicity to finfish and zooplankton, via laboratory bioassays. Thirteen microalgal species that co-cultured with Al. leei revealed large variability in the allelopathic effects of Al. leei on the test algae, with the growth inhibition rates ranging from 0 to 100%. The negative allelopathic effects of Al. leei on microalgae included loss of flagella and thus the motility, damages of chain structure, deformation in cell morphology, and eventually cell lysis. The finfish experienced 100% mortality within 24 h exposed to the live culture (2000-6710 cells·mL), while the rotifer and brine shrimp exhibited 96-100% and 90-100% mortalities within 48 h when exposed to 500-6000 cells·mL of Al. leei. The mortality of the test animals depended on the Al. leei cell density exposed, leading to a linear relationship between mortality and cell density for the finfish, and a logarithmic relationship for the two zooplankters. When exposed to the treatments using Al. leei whole live culture, cell-free culture medium, extract of algal cells in the f/2-Si medium, extract of methanol, and the re-suspended freeze-and-thaw algal cells, the test organisms (Ak. sanguinea and rotifers) all died at the cell density of 8100 cells·mL within 24 h. Toxin analyses by HILIC-ESI-TOF/MS and LC-ESI-MS/MS demonstrated that Al. leei did not produce PSP-toxins and 13-desmethyl spirolide C. Overall, our findings demonstrated potent allelopathy and toxicity of Al. leei, which do not only pose threats to the aquaculture industry, fisheries, and marine ecosystems but may also play a part role in the population dynamics and bloom formation of this species.
亚历山大藻属已被广泛认为是世界范围内引发麻痹性贝类中毒（PSP）的原因。然而，一些非 PSP 产毒物种已显示出鱼类致死毒性。在这里，我们通过实验室生物测定报告了来自马来西亚的亚历山大藻属 Leei 对其他藻类物种的化感活性及其对硬骨鱼和浮游动物的毒性。与 Al. leei 共培养的 13 种微藻物种显示出 Al. leei 对测试藻类的化感作用具有很大的可变性，抑制率范围从 0 到 100%。Al. leei 对微藻的负化感作用包括鞭毛丧失和因此的运动性、链结构的损伤、细胞形态的变形，最终导致细胞裂解。当暴露于活培养物（2000-6710 个细胞·mL）时，硬骨鱼在 24 小时内经历了 100%的死亡率，而当暴露于 500-6000 个细胞·mL 的 Al. leei 时，轮虫和丰年虾在 48 小时内表现出 96-100%和 90-100%的死亡率。测试动物的死亡率取决于暴露的 Al. leei 细胞密度，导致硬骨鱼的死亡率与细胞密度呈线性关系，两种浮游动物呈对数关系。当暴露于使用 Al. leei 全活培养物、无细胞培养物、f/2-Si 培养基中藻类细胞提取物、甲醇提取物和重新悬浮的冻融藻类细胞的处理时，测试生物（A. sanguinea 和轮虫）在 24 小时内均在 8100 个细胞·mL 的细胞密度下死亡。通过 HILIC-ESI-TOF/MS 和 LC-ESI-MS/MS 进行的毒素分析表明，Al. leei 不产生 PSP 毒素和 13-去甲基螺旋藻 C。总的来说，我们的研究结果表明，Al. leei 具有很强的化感作用和毒性，不仅对水产养殖业、渔业和海洋生态系统构成威胁，而且可能在该物种的种群动态和爆发形成中发挥作用。
