College of Resources and Environment, Southwest University, 1 Tiansheng Road, Beibei District, Chongqing 400716 China; National Base of International S&T Collaboration on Water Environmental Monitoring and Simulation in Three Gorges Reservoir Region, Chongqing 400716 China; College of Environment, Hohai University, No. 1 Xikang Road, Gulou District, Nanjing 210098, China.
College of Resources and Environment, Southwest University, 1 Tiansheng Road, Beibei District, Chongqing 400716 China; National Base of International S&T Collaboration on Water Environmental Monitoring and Simulation in Three Gorges Reservoir Region, Chongqing 400716 China.
Aquat Toxicol. 2023 May;258:106507. doi: 10.1016/j.aquatox.2023.106507. Epub 2023 Mar 22.
Secondary metabolites (toxins) production during harmful algal blooms (HABs) further increases the public health risks associated with water quality deterioration from anthropogenic eutrophication. In the present study, the dynamic pattern in the production of metabolites under different nutrient conditions in Ceratium-dominated spring HABs was investigated in Pengxi River, China. Results revealed five (5) important toxins all attributable to the Dinophyceae including azaspiracid 2&4, okadaic acid, tetrodotoxin, brevetoxin, and saxitoxin, each exhibiting certain levels of specificity to the ecosystem enrichments. In effect, while the production of azaspiracid 2 and okadaic acid was N-driven, azaspiracid 4 and tetrodotoxin were enhanced by Ca enrichment. The ambient HABs community structure shows absolute ecosystem dominance by a dinoflagellate, Ceratium hirundinella with relative abundance ((RA = 78.81%, p ˂ 0.05). However, P enrichment triggered a slight shift (p ≥ 0.05) in the HABs species structure within the cyanobacteria strictly represented by Chroococcus minor (RA = 26.60%) and Dolichospermum circinalis (RA = 23.91%) initiating possible emergency dominance. The effect of nutrient addition on biomass production as chlorophyll-a (Chl-a) confirmed a P-limited ecosystem juxtaposed by a secondary limitation by Ca. The significant stimulation on biomass as Chl-a from day 3 through day 4 by N and the multiple enrichments designated as NPFeCa was attributed to luxury consumption rather than limitation following N repletion thus delaying biomass accumulation. The study, therefore, offers useful insights into the dynamic pattern of toxins during spring HABs while it also provides comprehensive knowledge of the HABs impact predictions in the TGR.
次生代谢物（毒素）在有害藻华（HABs）期间的产生进一步增加了与人为富营养化导致的水质恶化相关的公共健康风险。本研究在中国彭溪河以硅藻为主的春季 HABs 中，研究了不同营养条件下代谢物产生的动态模式。结果表明，共有 5 种（5 种）重要毒素都归因于甲藻，包括azaspiracid 2&4、okadaic acid、tetrodotoxin、brevetoxin 和 saxitoxin，每种毒素都对生态系统的富集具有一定的特异性。实际上，虽然 azaspiracid 2 和 okadaic acid 的产生受 N 驱动，但 azaspiracid 4 和 tetrodotoxin 则受 Ca 富集的增强。环境中 HABs 群落结构显示出一种甲藻，旋链角毛藻（Ceratium hirundinella）具有绝对的生态系统优势，相对丰度（RA=78.81%，p<0.05）。然而，P 富集在蓝藻中引发了轻微的 HABs 物种结构变化（p≥0.05），严格代表蓝藻的微囊藻（Chroococcus minor）（RA=26.60%）和水华束丝藻（Dolichospermum circinalis）（RA=23.91%），这可能引发紧急优势。营养添加对生物量产生的影响作为叶绿素-a（Chl-a）证实了一个 P 限制的生态系统，其次是 Ca 限制。从第 3 天到第 4 天，N 对生物量作为 Chl-a 的显著刺激以及被指定为 NPFeCa 的多种富集是奢侈消费的结果，而不是 N 补充后的限制，因此延迟了生物量的积累。因此，该研究提供了关于春季 HABs 期间毒素动态模式的有用见解，同时还提供了关于 TGR 中 HABs 影响预测的全面知识。
