Harmful Algae最新文献

Pleurotus ostreatus polysaccharides improve microcystin-LR-induced intestinal damage in tadpoles by regulating the interaction between microbiota and intestine 平菇多糖通过调节微生物群与肠道的相互作用改善微囊藻毒素诱导的蝌蚪肠道损伤

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2026-01-05 DOI: 10.1016/j.hal.2026.103056

Minglan Fang , Jun He , Shijie Zhou , Pei Hong , Lixia Ke , Hailong Wu , Yilin Shu

Exposure to microcystins (MCs) can cause severe intestinal damage. This study aimed to assess the efficacy of Pleurotus ostreatus polysaccharide in alleviating intestinal damage induced by microcystin-leucine-arginine (MC-LR) in tadpoles. Over a 30-day period, tadpoles (Pelophylax nigromaculatus) received daily exposures to MC-LR and were provided with diets either supplemented with or devoid of P. ostreatus polysaccharide. Results revealed that feeding P. ostreatus polysaccharide conferred protection against MC-LR-induced intestinal damage by mitigating barrier damage, lowering intestinal permeability, and reducing the tissue burden of MC-LR. The LPS/TLR4 pathway response was attenuated, reducing inflammation, and oxidative stress-mediated apoptosis response was also diminished. Gram-negative bacteria (e.g., Bacteroides) in the intestine show a positive correlation with LPS content and the transcription of key genes in the LPS/TLR4 pathway. Metagenomic and metabolite analysis of intestinal contents revealed increased abundance of the alanine-glyoxylate aminotransferase gene (agxt)—the key enzyme converting glyoxylic acid to glycine—and elevated glycine content in the MC-LR-exposed group fed polysaccharide. Results from the corresponding fecal microbiota transplantation experiment aligned with the trends observed in the exposure experiment. Therefore, polysaccharide alleviates MC-LR-induced intestinal damage by enhancing intestinal microbiota-mediated glycine synthesis, supplying raw materials for intestinal GSH production, reducing oxidative stress levels, and simultaneously dampening the LPS/TLR4 pathway response. Moreover, feeding polysaccharides might also regulate the intestine’s defense against pathogens after MC-LR exposure by enhancing lysozyme activity. There is no evidence of intestinal damage in the P. ostreatus exopolysaccharide group. This study highlights for the first time the role of P. ostreatus polysaccharides in mitigating MC-LR-induced intestinal tissue damage, potentially offering novel insights for their application in aquaculture.

暴露于微囊藻毒素（MCs）可导致严重的肠道损伤。本研究旨在评价平菇多糖对小蝌蚪微胱氨酸-亮氨酸-精氨酸（MC-LR）诱导的肠道损伤的缓解作用。在30天的时间里，蝌蚪（Pelophylax nigromaculatus）每天暴露于MC-LR，并提供添加或不添加P. ostreatus多糖的饮食。结果表明，饲用P. ostreatus多糖可减轻MC-LR诱导的肠道屏障损伤，降低肠道通透性，减轻MC-LR的组织负担，从而对MC-LR诱导的肠道损伤起到保护作用。LPS/TLR4通路反应减弱，炎症减轻，氧化应激介导的细胞凋亡反应也减弱。肠内革兰氏阴性菌（如拟杆菌）与LPS含量及LPS/TLR4通路关键基因的转录呈正相关。肠道内容物的宏基因组学和代谢物分析显示，在mc - lr暴露组中，将乙醛酸转化为甘氨酸的关键酶丙氨酸-乙醛酸氨基转移酶基因（agxt）丰度增加，甘氨酸含量升高。相应的粪便微生物群移植实验结果与暴露实验中观察到的趋势一致。因此，多糖通过增强肠道菌群介导的甘氨酸合成，为肠道GSH生产提供原料，降低氧化应激水平，同时抑制LPS/TLR4通路反应，减轻mc - lr诱导的肠道损伤。此外，饲喂多糖还可能通过增强溶菌酶活性来调节暴露于MC-LR后肠道对病原体的防御。没有证据表明，在大肠杆菌胞外多糖组肠道损伤。本研究首次强调了P. ostreatus多糖在减轻mc - lr诱导的肠道组织损伤中的作用，可能为其在水产养殖中的应用提供新的见解。

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引用次数: 0

Tracking marine phycotoxins: spatial distribution and source elucidation of domoic acid and lipophilic shellfish toxins in the Beibu Gulf, South China Sea 海洋藻毒素追踪：南海北部湾软骨藻酸和亲脂贝类毒素的空间分布和来源解析

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-12-31 DOI: 10.1016/j.hal.2025.103048

Ying Ji , Guowang Yan , Guixiang Wang , Yadong Cao , Jiangbing Qiu , Tianshen Li , Xin Luo , Wenlu Lan , Zhaohui Wang , Aifeng Li

Harmful algal blooms (HABs) pose escalating threats to marine ecosystems and seafood safety worldwide, particularly in nearshore waters. The Beibu Gulf, located in the northwestern South China Sea, supports rich biodiversity and serves as a major fishing area. To comprehensively understand the current status of phycotoxin pollution, we conducted a basin-wide cruise survey in August 2021, collecting 60 phytoplankton samples to characterize the spatial distribution, compositional profile, and molecular origins of 12 target marine phycotoxins, along with their key environmental drivers. Domoic acid (DA), pectenotoxin-2 (PTX2), homo-yessotoxin (homoYTX), and gymnodimine A (GYM-A) were the predominant phycotoxins detected, whereas okadaic acid (OA), dinophysistoxin (DTX1), and yessotoxin (YTX) were found sporadically (< 6.7% detection rate). The DA was present in 20% of samples (mean 14,424 pg L⁻¹, max 163,434 pg L⁻¹), PTX2 in 36.7% (mean 508 pg L⁻¹, max 2995 pg L⁻¹), homoYTX in 43.3% (mean 1717 pg L⁻¹, max 42,680 pg L⁻¹), and GYM-A exhibited the highest detection rate at 68.3% (mean 37 pg L⁻¹, max 902 pg L⁻¹). Phycotoxin concentrations were markedly higher in the northern waters than in the southern gulf. Metabarcoding revealed 14 potential toxigenic microalgae, 12 of which belonged to Dinophyceae. Redundancy analysis indicated that concentrations of the four dominant phycotoxins were positively correlated with dissolved oxygen and chlorophyll a, but negatively correlated with salinity (p < 0.05). This suggests that low-salinity (28−31), resulting from terrestrial inputs and marine circulation, create favorable niches for toxigenic species. This study elucidates the phycotoxin profiles and their putative toxigenic microalgae in the Beibu Gulf, while highlighting environmental factors that promote phycotoxin production. These findings provide foundational insights into HAB dynamics in tropical estuarine systems, aiding future monitoring and management efforts in the region.

有害藻华（HABs）对全球海洋生态系统和海产品安全构成日益严重的威胁，特别是在近岸水域。北部湾位于中国南海西北部，拥有丰富的生物多样性，是一个主要的渔区。为了全面了解藻毒素污染现状，我们于2021年8月进行了一项全流域的邮轮调查，收集了60份浮游植物样本，以表征12种目标海洋藻毒素的空间分布、组成剖面、分子来源及其主要环境驱动因素。藻毒素以软骨藻酸（DA）、果皮毒素-2 （PTX2）、同型叶裸毒素（homoYTX）、裸子二胺A （gymnodimine A）为主，冈田酸（OA）、藻毒素（DTX1）、叶裸毒素（YTX）偶有检出（检出率6.7%）。DA的检出率为20%（平均14424 pg L−1，最大163434 pg L−1），PTX2的检出率为36.7%（平均508 pg L−1，最大2995 pg L−1），homoYTX的检出率为43.3%（平均1717 pg L−1，最大42680 pg L−1），而gyma的检出率最高，为68.3%（平均37 pg L−1，最大902 pg L−1）。北部水域的藻毒素浓度明显高于南部海湾。元条形码鉴定出14种潜在产毒微藻，其中12种属于藻门。冗余分析表明，4种优势藻毒素浓度与溶解氧和叶绿素a呈正相关，与盐度呈负相关（p < 0.05）。这表明，陆地输入和海洋环流导致的低盐度（28−31）为产毒物种创造了有利的生态位。本研究阐明了北部湾藻毒素的分布及其推测的产毒微藻，同时强调了促进藻毒素产生的环境因素。这些发现为了解热带河口系统中有害藻华的动态提供了基础见解，有助于该地区未来的监测和管理工作。

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引用次数: 0

Impact of brewer’s spent grain on freshwater and marine harmful algal bloom species 啤酒废粮对淡水和海洋有害藻华的影响

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-12-27 DOI: 10.1016/j.hal.2025.103047

C. Taylor Armstrong , Michael Gonsior , Allen R. Place

Barley straw bales are commonly used to control cyanobacterial growth in lakes, but the method is time-consuming, labor-intensive, and its effectiveness requires deployment of bales prior to bloom formation. This study investigates brewer’s spent grain (BSG), a byproduct of the brewing process, as an alternative source of allelopathic chemicals shown to negatively impact toxic microalgae. Water extracts of BSG, barley straw, and Sargassum natans were tested for their ability to inhibit the growth of toxin-producing (Microcystis aeruginosa and Karenia brevis) as well as non-toxin-producing (Tetradesmus obliquus and Phaeodactylum tricornutum) algal species. BSG extracts at concentrations above 250 mg/L effectively inhibited the growth of both freshwater and marine toxin-producing species (M. aeruginosa and K. brevis), while exhibiting no significant effect on the diatom and chlorophyte species tested (T. obliquus and P. tricornutum). Additional experiments using antibiotics with K. brevis suggest that growth inhibition may be mediated by changes in the bacterial community, though the specific mechanism of M. aeruginosa death remains unresolved. A microcosm experiment further evaluated the impact of BSG extract on a natural bloom of cyanobacteria (Raphidiopsis raciborskii) in lake water. Application of 250 mg/L BSG extract to natural lake water shifted the community composition from cyanobacteria to chlorophyte dominance. These findings highlight the potential use for a brewery’s waste product as a cost-effective tool for managing harmful algal blooms. However, the high concentrations required, excess nutrient content in BSG, and impact on bacterial communities indicate limitations for large-scale application.

大麦秸秆包通常用于控制湖泊中的蓝藻生长，但该方法耗时，劳动密集，其有效性需要在水华形成之前部署包。这项研究调查了啤酒酿造过程的副产品啤酒的废谷物（BSG），作为化感化学物质的替代来源，显示出对有毒微藻的负面影响。我们测试了BSG、大麦秸秆和马尾藻水提取物对产毒藻类（铜绿微囊藻和短Karenia brevis）和非产毒藻类（斜四角藻和三角褐藻）生长的抑制能力。浓度超过250 mg/L的BSG提取物可有效抑制淡水和海洋产毒物种（M. aeruginosa和K. brevis）的生长，而对硅藻和绿藻物种（T. obliquus和P. tricornutum）的生长无显著影响。使用抗生素对短克雷伯氏菌进行的其他实验表明，生长抑制可能是由细菌群落的变化介导的，尽管铜绿假单胞菌死亡的具体机制尚不清楚。通过微观实验进一步评估了BSG提取物对湖水中蓝藻（Raphidiopsis raciborskii）自然繁殖的影响。250mg /L BSG提取物在天然湖水中处理后，群落组成由蓝藻为主向绿藻为主转变。这些发现强调了啤酒厂废物作为一种经济有效的工具来管理有害藻华的潜在用途。然而，所需的高浓度、BSG中过量的营养含量以及对细菌群落的影响表明了大规模应用的局限性。

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引用次数: 0

Morphological and physiological adaptations of Dolichospermum flos-aquae to turbulence 水莲对湍流的形态和生理适应

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-12-16 DOI: 10.1016/j.hal.2025.103046

Yulin Wang, Wenting Zhong, Ruiwen Chen, Qin Tang, Gongzheng Li, Zhou Yang, Yuan Huang

Heterocystous cyanobacteria are increasingly forming surface blooms in freshwater ecosystems, with massive proliferation events influenced by multiple environmental factors—among which turbulence has emerged as a pivotal driver. This study investigated the effects of different turbulence intensities (ranging from 10⁻⁵ to 10⁻² m² s⁻³, within the natural environmental range) on the morphology and physiology of the bloom-forming diazotroph Dolichospermum flos-aquae. Results showed that high-intensity turbulence promoted population growth, dissolved nitrogen uptake, and photosynthetic performance of D. flos-aquae. Under high turbulence conditions, filament length exhibited greater uniformity alongside an increase in average length. Furthermore, heterocyst production was markedly enhanced, with no alteration in the spatial localization of heterocysts along filaments. These phenotypic responses were associated with upregulated carbon and nitrogen metabolisms—particularly nitrogen assimilation and carbon fixation—supported by the increased expression of key functional genes. Collectively, these findings reveal the morphological and physiological adaptive strategies of heterocystous cyanobacteria to turbulent environments, thereby advancing our understanding of diazotrophic cyanobacterial bloom dynamics in hydrologically dynamic freshwater ecosystems.

在淡水生态系统中，异囊蓝藻越来越多地形成地表水华，其大规模增殖事件受到多种环境因素的影响，其中湍流已成为关键驱动因素。本研究研究了不同湍流强度（10−5 ~ 10−2 m2 s−3，在自然环境范围内）对重氮营养菌水藻（Dolichospermum flos-aquae）形态和生理的影响。结果表明，高强度湍流对水藻种群生长、溶氮吸收和光合性能有促进作用。在高湍流条件下，灯丝长度表现出更大的均匀性，同时平均长度增加。此外，杂种囊的产生明显增强，但杂种囊沿丝的空间定位没有改变。这些表型反应与碳氮代谢的上调有关，特别是氮同化和碳固定，并得到关键功能基因表达增加的支持。总的来说，这些发现揭示了异囊蓝藻对湍流环境的形态和生理适应策略，从而促进了我们对水文动态淡水生态系统中重氮营养蓝藻华动态的理解。

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引用次数: 0

Zooplankton feeding behaviour and survival to toxic and non-toxic cyanobacteria during the seasonal bloom progression of a eutrophic lake 富营养化湖泊季节性水华过程中浮游动物对有毒和无毒蓝藻的摄食行为和生存

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-12-12 DOI: 10.1016/j.hal.2025.103045

Pinelopi Ntetsika , Salomé Stauffer , Stefanie Eyring , Marta Reyes , Xuejian Wang , Elisabeth M.-L. Janssen , Francesco Pomati

Harmful cyanobacterial blooms pose increasing threats to aquatic ecosystems and human health; yet, the role of zooplankton grazing in regulating blooms remains understudied. We investigated the seasonal feeding behaviour and fitness consequences of feeding preferences in natural zooplankton communities for toxic (microcystin-producing) versus non-toxic cyanobacteria across temperature gradients in eutrophic Lake Greifen, Switzerland. We conducted monthly experiments from April to October 2023 to test the grazing behaviour of four zooplankton groups (daphnids, calanoid copepods, cyclopoid copepods, and microzooplankton) exposed to mixed diets of green algae and either toxic or non-toxic Microcystis strains at 15 °C and 25 °C.

Contrary to expectations of cyanobacteria avoidance, zooplankton exhibited predominantly non-selective grazing throughout the seasonal succession, consuming both toxic and non-toxic cyanobacteria at similar rates, regardless of temperature. Notably, during the peaks of phytoplankton abundance (April and September), mesozooplankton demonstrated a selective preference for cyanobacteria over green algae, particularly non-toxic strains. Temperature effects were subtle but revealed metabolic constraints: elevated temperatures occasionally triggered selective consumption of cyanobacteria in copepods, while fitness costs (survival) from exposure to toxic species were mostly restricted to transitional bloom periods and high-temperature conditions.

These findings suggest that toxic cyanobacteria may not always evade grazing pressure through secondary metabolite deterrent effects. Our results suggest that zooplankton communities can adapt and graze on cyanobacteria regardless of toxicity under the tested conditions, even during bloom conditions. These observations highlight the potential for zooplankton to interact with cyanobacterial populations, which may have implications for bloom prediction and management strategies, particularly under climate warming scenarios.

有害的蓝藻繁殖对水生生态系统和人类健康构成越来越大的威胁；然而，浮游动物放牧在调节藻华中的作用仍未得到充分研究。我们研究了瑞士富营养化湖Greifen天然浮游动物群落中有毒（产生微囊藻毒素）与无毒蓝藻在不同温度梯度下的季节性摄食行为和摄食偏好的适应性后果。我们于2023年4月至10月进行了月度实验，测试了在15°C和25°C条件下，4种浮游动物类群（水蚤类、花萼类桡足类、环足类桡足类和微型浮游动物）在绿藻和有毒或无毒微囊藻菌株混合饮食中的放牧行为。与预期的避免蓝藻相反，浮游动物在整个季节演替中表现出主要的非选择性放牧，无论温度如何，它们以相似的速度消耗有毒和无毒的蓝藻。值得注意的是，在浮游植物丰度的高峰期（4月和9月），中浮游动物表现出对蓝藻的选择性偏好，而不是绿藻，特别是无毒菌株。温度影响是微妙的，但揭示了代谢限制：升高的温度偶尔会触发桡足类对蓝藻的选择性消耗，而暴露于有毒物种的适应成本（生存）主要局限于过渡开花期和高温条件。这些发现表明，有毒的蓝藻可能并不总是通过次级代谢物的威慑作用来逃避放牧压力。我们的研究结果表明，在测试条件下，浮游动物群落可以适应并以蓝藻为食，而不考虑毒性，即使在水华条件下也是如此。这些观察结果突出了浮游动物与蓝藻种群相互作用的潜力，这可能对水华预测和管理策略产生影响，特别是在气候变暖的情况下。

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引用次数: 0

Ca2+ binding to soluble extracellular polymeric substances promotes loosening of Microcystis colonies under high Ca2+conditions Ca2+结合可溶性细胞外聚合物质促进微囊藻菌落在高Ca2+条件下的松动

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-12-12 DOI: 10.1016/j.hal.2025.103044

Ping Zhang , Caihong Qin , Chao Xiong , Xinyue Li , Bin Yan , Xuemei Chen , Han Wang , Kai Li , Yan Xiao

Colony formation is crucial for the development of Microcystis blooms, which pose a significant ecological challenge on a global scale. Previous studies have demonstrated that bound extracellular polymeric substances (EPS) play a vital role in the colony formation process. However, the influence of the coexisting soluble EPS (S-EPS) on Microcystis colony formation remains unclear. This study investigated the effect of S-EPS on the colony formation of Microcystis induced by high concentrations of Ca²⁺. The results indicated that the combined treatment of S-EPS (100 mg/L) and Ca²⁺ (200 mg/L) resulted in loosely bound Microcystis colonies, in contrast to the dense colonies induced by 200 mg/L Ca²⁺. In contrast, no colonies were formed when the Microcystis cells were treated with S-EPS alone. In addition, the incorporation of 100 mg/L of S-EPS into 200 mg/L Ca²⁺-treated Microcystis cells reduced the cell zeta potential by 2.09 mV and decreased surface hydrophobicity, as indicated by a 1.60° increase in the water contact angle that increased the interaction energy among Microcystis cells. The energy barrier increased from 293.32 KT in the 200 mg/L Ca²⁺ treatment groups to 538.10 KT following the introduction of 100 mg/L S-EPS, indicating a reduced propensity for colony formation after S-EPS addition. Further studies indicated that Ca²⁺ in the inoculum exhibited a strong binding capacity with the OH groups of polysaccharides (K_M = 0.032 ± 0.004), CC stretching of aromatics (K_M = 0.022 ± 0.003) and tryptophan-like proteins (K_M = 0.013 ± 0.001) from S-EPS. This resulted in extensive networks and lower free Ca²⁺ concentrations that reduced the bound EPS secretion by approximately 0.15 pg/cell compared to that with a Ca²⁺ concentration of 200 mg/L. This study provides new insights into the mechanism of colony formation in Microcystis.

微囊藻在全球范围内对生态构成了重大挑战，而菌落的形成对微囊藻华的发展至关重要。先前的研究表明，结合的细胞外聚合物（EPS）在集落形成过程中起着至关重要的作用。然而，共存的可溶性EPS （S-EPS）对微囊藻菌落形成的影响尚不清楚。本研究探讨了S-EPS对高浓度Ca2+诱导微囊藻菌落形成的影响。结果表明，S-EPS （100 mg/L）和Ca2+ (200 mg/L)联合处理可形成松散结合的微囊藻菌落，而Ca2+ (200 mg/L)可形成致密的菌落。相比之下，单独用S-EPS处理微囊藻细胞时，没有形成菌落。此外，将100 mg/L S-EPS掺入200 mg/L Ca2+处理的微囊藻细胞中，使细胞zeta电位降低2.09 mV，表面疏水性降低，水接触角增加1.60°，增加了微囊藻细胞之间的相互作用能。200 mg/L Ca2+处理组的能量垒由293.32 KT增加到100 mg/L S-EPS处理组的538.10 KT，表明添加S-EPS后菌落形成倾向降低。进一步研究表明，接种物中的Ca2+与S-EPS中多糖（KM = 0.032±0.004）、芳烃（KM = 0.022±0.003）和色氨酸样蛋白（KM = 0.013±0.001）的OH基团具有较强的结合能力。这导致了广泛的网络和较低的游离Ca2+浓度，与Ca2+浓度为200 mg/L的细胞相比，结合的EPS分泌减少了约0.15 pg/细胞。本研究为微囊藻菌落形成机制的研究提供了新的思路。

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引用次数: 0

From laboratory to field: Temperature rise triggers increased release and toxicity of microcystins in Microcystis aeruginosa 从实验室到现场：温度升高引发铜绿微囊藻中微囊藻毒素的释放和毒性增加

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-12-09 DOI: 10.1016/j.hal.2025.103042

Shihao Wang , Yurong Gu , Weilu Li , Qingju Xue , Xinfeng Cheng , Chen Cheng , Liqiang Xie

Temperature rise increases the risk of microcystins (MCs) in aquatic ecosystems by affecting toxin-producing cyanobacteria, but strain-specific responses remain unclear. This study investigated the growth, MCs production and release, isomer composition, and mcyB and mcyH genes expression of two Microcystis aeruginosa strains (FACHB-1322 and FACHB-1203) during 20-day cultivation at temperatures of 15 °C, 20 °C, and 28 °C, with the ecological relevance of laboratory findings corroborated through field data conducted in Lake Taihu. The results revealed that by the endpoint of cultivation, M. aeruginosa FACHB-1322 exhibited a compensatory growth strategy at high-temperature (28 °C), while M. aeruginosa FACHB-1203 demonstrated eurythermal adaptation. Total MCs content and mcyB and mcyH expression decreased with rising temperature in M. aeruginosa FACHB-1322 but increased in M. aeruginosa FACHB-1203. Notably, both strains showed elevated extracellular MCs content and MCs release ratio with rising temperature. Regarding isomer profiles, M. aeruginosa FACHB-1322 primarily produced and released MC-LR, whereas M. aeruginosa FACHB-1203 predominantly produced MC-RR but exhibited temperature-enhanced MC-LR release. Critically, high-temperature specifically induced the production and release of the highly toxic MC-YR in both strains. Field data further confirmed that temperature rise promotes MCs release and increases the proportion of extracellular MC-LR. Thus, temperature rise amplifies the ecological risk of MCs through dual mechanisms: favoring the growth with high MCs release capacity strain and driving a compositional shift of MC isomers from less toxic isomers toward highly toxic isomers.

温度升高会影响产生毒素的蓝藻，从而增加水生生态系统中微囊藻毒素（MCs）的风险，但菌株特异性反应尚不清楚。本研究研究了两株铜绿微囊藻（FACHB-1322和FACHB-1203）菌株在15℃、20℃和28℃条件下的生长、MCs的产生和释放、异构体组成以及mcyB和mcyH基因的表达，并通过太湖现场数据验证了实验室研究结果的生态学相关性。结果表明，在培养结束时，M. aeruginosa FACHB-1322表现出高温（28°C）的代偿生长策略，而M. aeruginosa FACHB-1203表现出高温适应。随着温度升高，铜绿假单胞菌FACHB-1322的总MCs含量和mcyB、mcyH表达量降低，而FACHB-1203的MCs含量升高。值得注意的是，两种菌株的胞外MCs含量和MCs释放率均随温度升高而升高。就异构体谱而言，M. aeruginosa FACHB-1322主要产生和释放MC-LR，而M. aeruginosa FACHB-1203主要产生MC-RR，但表现出温度增强的MC-LR释放。关键的是，高温特异性地诱导了两种菌株中高毒性MC-YR的产生和释放。现场数据进一步证实，温度升高促进了MCs的释放，增加了胞外MC-LR的比例。因此，温度升高通过双重机制放大了MCs的生态风险：有利于MCs高释放能力菌株的生长，推动MCs同分异构体的组成从毒性较小的同分异构体向毒性较大的同分异构体转变。

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引用次数: 0

Pixel-scale satellite forecasting of cyanobacteria in Florida lakes 佛罗里达湖泊蓝藻的像素级卫星预报

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-12-09 DOI: 10.1016/j.hal.2025.103041

Maxwell R.W. Beal , Blake Schaeffer

Rapid proliferation of potentially toxin-producing cyanobacteria (cyanobacterial harmful algal blooms, cHABs) is a significant challenge for water resource managers. The U.S. Harmful Algal Bloom and Hypoxia Research Control Act calls for robust approaches to forecasting cHABs in lakes and reservoirs. A previous national study developed a lake scale Bayesian spatiotemporal model to forecast weekly chlorophyll-a exceedance probability in 2192 satellite resolved lakes using Sentinel-3 Ocean Land Colour Instrument data. Building on this foundation, this study developed a machine learning based, spatially explicit forecasting model at the 300-m pixel scale for Sentinel-3 resolvable lakes, conditioned on environmental variables from 2017 – 2024. Three machine learning models were constructed for Sentinel-3 resolvable lakes across Florida to generate ensemble forecasts of chlorophyll-a concentration and World Health Organization Alert Level categories with multi-week leads. The pixel scale metric significantly increased the number of resolvable bloom events, recording 4682 (33%) more exceedance events than the lake scale metric. The best performing model (random forest) achieved 88.2% accuracy at Alert Level 1 and 92.2% accuracy at Alert Level 2. Overall R² was 0.56 and mean absolute error was 5.4

μ g L^{- 1}

The best performing model had notable skill at 1–2 week leads but diminished at a 4-week horizon. Probabilistic forecast performance shows that the model predicted observed chlorophyll concentrations and WHO Alert Levels with skill. Direct comparison showed similar skill between the lake and pixel scale forecast.

可能产生毒素的蓝藻（蓝藻有害藻华，cHABs）的快速增殖是水资源管理者面临的重大挑战。美国有害藻华和缺氧研究控制法案要求采用强有力的方法来预测湖泊和水库中的有害藻华。先前的一项国家研究开发了一个湖泊尺度贝叶斯时空模型，利用Sentinel-3海洋陆地颜色仪器数据预测2192个卫星分辨率湖泊每周叶绿素A超标的概率。在此基础上，本研究基于2017 - 2024年的环境变量，开发了基于机器学习的哨兵3号可解析湖泊300米像素尺度的空间明确预测模型。为佛罗里达州的Sentinel-3可分解湖泊构建了三个机器学习模型，以生成叶绿素-a浓度和世界卫生组织警报级别类别的多周领先的整体预测。像素尺度显著增加了可解析的水华事件的数量，比湖泊尺度多记录了4682次（33%）的超标事件。表现最好的模型（随机森林）在警报级别1和警报级别2的准确率分别达到了88.2%和92.2%。总体R2为0.56，平均绝对误差为5.4 μgL−1，表现最好的模型在1 - 2周时具有显著的技能，但在4周时有所下降。概率预报性能表明，该模型能较好地预测观测到的叶绿素浓度和WHO警戒级别。湖尺度预报与像素尺度预报的直接对比表明，二者的预报技巧相近。

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引用次数: 0

Environmentally relevant concentrations of the antibiotic azithromycin enhance the toxicity of the cyanobacterium Microcystis aeruginosa on the water flea Daphnia similis 环境相关浓度的抗生素阿奇霉素增强了铜绿微囊藻蓝藻对水蚤的毒性

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-12-09 DOI: 10.1016/j.hal.2025.103040

Michael Ribas Celano , Júlia Vianna De Pinho , Sandra Maria Feliciano de Oliveira e Azevedo , Mauro Cesar Palmeira Vilar

Artificial eutrophication has degraded water bodies worldwide, promoting harmful cyanobacterial blooms (CyanoHABs). In addition to nutrient loading, antibiotics are increasingly being introduced into aquatic environments, exacerbating water pollution, and the impact on biota. Among antibiotics, azithromycin (AZT) has displayed a rise in environmental occurrence following its increased global consumption during the COVID-19 pandemic. Therefore, we assessed the effect of environmentally relevant concentrations of AZT (≤3 μg l^-1) on the interaction between the toxic cyanobacterium Microcystis aeruginosa and the freshwater zooplankton Daphnia similis. The acute toxicity of both the cyanobacterium and antibiotic on Daphnia was determined, followed by an herbivory and a life-table assay to assess behavioral and sublethal effects under single and combined exposures. The 96-hour LC₅₀ and EC₅₀ for AZT were 35.2 and 29.1 mg l^-1, respectively. The risk quotient for D. similis was 0.098, indicating a low ecological risk (RQ < 0.1). Regarding M. aeruginosa, 96-hour LC₅₀ and EC₅₀ values were 713 and 303 μgC l^-1, respectively, with RQ values >700, indicating a high ecological risk. Environmental levels of AZT did not affect Daphnia, while the cyanobacterium inhibited zooplankter feeding and life-table responses. However, combined exposure to AZT and toxic M. aeruginosa resulted in a greater decrease in survival and overall population fitness, besides an increased cyanobacterial ingestion. These findings suggest that environmental concentrations of AZT may intensify the impacts of toxic cyanobacteria on zooplankton. This highlights the need for further research into the mechanisms underlying the enhanced toxicity of cyanobacteria promoted by antibiotics at environmental levels.

人工富营养化已经使世界范围内的水体退化，促进了有害的蓝藻华（CyanoHABs）。除了营养物负荷外，越来越多的抗生素被引入水生环境，加剧了水污染和对生物群的影响。在抗生素中，阿奇霉素（AZT）在2019冠状病毒病（COVID-19）大流行期间全球消费量增加后，在环境中的发生率有所上升。因此，我们评估了环境相关浓度（≤3 μg -1） AZT对有毒蓝藻铜绿微囊藻（Microcystis aeruginosa）与淡水浮游动物Daphnia similis相互作用的影响。确定了蓝藻和抗生素对水蚤的急性毒性，随后进行了草食和生命表试验，以评估单次和联合暴露下的行为和亚致死效应。AZT的96小时LC₅0和EC₅0分别为35.2和29.1 mg l-1。相似金蝇的风险商为0.098，生态风险较低（RQ < 0.1）。关于M. aeruginosa， 96小时LC₅0和EC₅0值分别为713和303 μgC l-1， RQ值>；700，表明生态风险高。环境水平的AZT不影响水蚤，而蓝藻抑制浮游动物的摄食和生命表反应。然而，除了蓝藻菌摄入增加外，AZT和有毒M.铜绿假单胞菌的联合暴露导致存活率和总体种群适应性的更大下降。这些发现表明，环境浓度的AZT可能会加剧有毒蓝藻对浮游动物的影响。这突出了需要进一步研究的机制，潜在的增强毒性的蓝藻促进抗生素在环境水平。

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引用次数: 0

Characterizing seasonal persistence of low levels of Pseudo-nitzschia australis in the Gulf of Maine with environmental DNA 用环境DNA表征缅因湾低水平的南方伪nitzschia季节性持久性

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-12-04 DOI: 10.1016/j.hal.2025.103039

Sydney M. Greenlee , Robin S. Sleith , Damian C. Brady , Peter D. Countway

The potent neurotoxin domoic acid is produced by some species of diatoms in the genus Pseudo-nitzschia, which can lead to amnesic shellfish poisoning (ASP) events in marine food webs. Of the toxin-producing Pseudo-nitzschia, P. australis has caused the most toxic and widespread events, making it a species of concern. Toxic and non-toxic Pseudo-nitzschia species cannot be distinguished easily by light microscopy, necessitating molecular testing. We designed a real-time quantitative PCR assay for rapid and accurate detection of P. australis in environmental DNA (eDNA) samples, targeting the intergenic region between rbcS and psaI in the chloroplast genome, providing species-level specificity and high sensitivity. Experimental determination of rbcS gene copies per cell revealed a limit of detection equivalent to 1 P. australis cell per liter of seawater, facilitating the early detection of this toxic species. This novel qPCR assay was applied to eDNA samples collected from Maine coastal waters between 2021 - 2024 to characterize the nearshore dynamics of P. australis within a regional hub for shellfish aquaculture. Though relatively rare, P. australis peaked in abundance in mid-October when conditions became favorable for this species following convective overturning. The eDNA assay was able to detect a low P. australis signal at a time when ‘large’ Pseudo-nitzschia spp. cell counts approached 8000 cells l^-1 (by microscopy) while qPCR-based estimates of P. australis remained below 10 cells l^-1. We demonstrate an eDNA approach for the early detection of HABs, calibration of qPCR assays to cell counts, and provide a new tool for coastal management.

软骨藻酸是一种强效神经毒素，可引起海洋食物网中失忆性贝类中毒（ASP）事件。在产生毒素的伪nitzschia中，australis引起了毒性最强和传播最广的事件，使其成为一个值得关注的物种。有毒和无毒的伪尼茨氏菌无法通过光学显微镜轻易区分，因此需要进行分子检测。我们设计了一种实时定量PCR方法，用于快速准确地检测环境DNA （eDNA）样品中的南方稻瘟菌，该方法针对叶绿体基因组中红细胞和psaI之间的基因间区域，具有种水平的特异性和高灵敏度。对每个细胞的红细胞基因拷贝数的实验测定显示，每升海水的检出限相当于1个南鳗细胞，有利于早期发现这种有毒物种。该新型qPCR检测方法应用于2021 - 2024年间从缅因州沿海水域收集的eDNA样本，以表征贝类养殖区域中心内南棘鲷的近岸动态。虽然相对稀少，但在对流翻转后的10月中旬条件变得有利时，南棘的丰度达到顶峰。当伪尼茨氏菌的“大”细胞计数接近8000细胞l-1（显微镜下）时，eDNA检测能够检测到低南方血吸虫信号，而基于qpcr的南方血吸虫估计仍低于10细胞l-1。我们展示了一种用于早期检测赤潮的eDNA方法，校准qPCR检测细胞计数，并为海岸管理提供了一种新的工具。

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引用次数: 0