Harmful Algae最新文献_第2页

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

Spatiotemporal dynamics of Phaeocystis globosa genotypes in a P. globosa bloom in the Beibu Gulf, China revealed differential contributions to bloom development 北部湾全球褐囊藻（Phaeocystis globbosa）基因型的时空动态揭示了其对华花发育的差异贡献

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-11-27 DOI: 10.1016/j.hal.2025.103032

Yifei Wang , Jinxiu Wang , Rencheng Yu , Nansheng Chen

Recent studies suggest that the cosmopolitan harmful algal bloom (HAB) species Phaeocystis globosa has high genetic diversity, with two major genotypes (sASV_1 and sASV_2) characterized through comparative analysis of P. globosa strains. However, how they differ from each other phenotypically, and how they contribute differentially to bloom development remain unclear. In this study, phenotypic analysis of strains belonging to these two P. globosa genotypes revealed that the average cell size of sASV_2 strains was significantly larger than that of sASV_1 strains. Furthermore, sASV_1 strains contained two characteristic pigments 19′-butanoyloxyfucoxanthin (But-fuco) and 19′-hexanoyloxyfucoxanthin (Hex-fuco), while sASV_2 strains contained only But-fuco. Metabarcoding analysis of environmental samples collected during a P. globosa bloom in the Beibu Gulf in 2019 revealed that these genotypes showed different spatiotemporal distribution patterns, suggesting their differential contribution to the P. globosa bloom. And correlation analysis of environmental factors indicated that the responses of P. globosa genotypes to environmental factors showed significant differences. This study confirmed the existence of two P. globosa genotypes with substantial differences in cell sizes and pigment compositions for the first time, and showed that different genotypes may contribute differently during P. globosa bloom development. Results from this study set up a platform for exploring molecular mechanisms underlying genotype-specific P. globosa bloom development, and for monitoring causative strains leading to P. globosa bloom development.

近年来的研究表明，世界性有害藻华（HAB）物种globosa Phaeocystis具有较高的遗传多样性，通过对globosa菌株的比较分析，确定了两种主要基因型（sASV_1和sASV_2）。然而，它们在表型上如何不同，以及它们如何对开花发育做出不同的贡献仍不清楚。本研究对这两个基因型的菌株进行表型分析发现，sASV_2菌株的平均细胞大小明显大于sASV_1菌株。sASV_1菌株含有19′-丁烷氧基岩藻黄素（But-fuco）和19′-己烷氧基岩藻黄素（hexx -fuco）两种特征色素，而sASV_2菌株仅含有But-fuco。对2019年北部湾一次球藻华期间采集的环境样本进行元条形码分析发现，这些基因型呈现出不同的时空分布模式，表明它们对球藻华的贡献存在差异。环境因子的相关分析表明，不同基因型对环境因子的响应存在显著差异。本研究首次证实了两种基因型的存在，它们在细胞大小和色素组成上存在显著差异，并表明不同基因型在开花发育过程中可能起着不同的作用。本研究结果为探索基因型特异性球形假单胞菌开花发生的分子机制和监测导致球形假单胞菌开花发生的致病菌株提供了平台。

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引用次数: 0

Urban eutrophication enhances domoic acid production by Pseudo-nitzschia in the Southern California Bight 城市富营养化促进了南加州湾伪耐氏藻的软骨藻酸生产

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-11-18 DOI: 10.1016/j.hal.2025.103023

Marco Sandoval-Belmar , Faycal Kessouri , Jayme Smith , Allison R. Moreno , Clarissa Anderson , Raphael M. Kudela , Martha Sutula , Minna Ho , Pierre Damien , Claudia Benitez-Nelson , James C. McWilliams , Daniele Bianchi

The diatom genus Pseudo-nitzschia and its neurotoxin domoic acid (DA) are major contributors to harmful algal blooms (HABs) along the U.S. West Coast, affecting marine ecosystems and human health. Observations implicate anthropogenic nutrient inputs, upwelling, and climate variability, but their relative importance remains unclear. We couple a mechanistic DA-production model, constrained by culture experiments, to a three-dimensional ocean biogeochemical model to simulate the DA cycle in the Southern California Bight, an urbanized region with a population of 23 million. Using 1-km resolution simulations for 2006–2017 we compare two cases: (i) an anthropogenic scenario (ANTH), in which rivers and wastewater outfalls supply freshwater and enhanced nutrient loads, and (ii) a control (CTRL) with freshwater-only fluxes, and nutrient loads set to zero. Skill assessments show that ANTH captures observed seasonal patterns, vertical distributions, and horizontal gradients of particulate DA. Performance is highest in the San Pedro and Santa Barbara Channels, but lower elsewhere, indicating need for refinements to capture local HAB dynamics. Comparison of the two simulations shows that terrestrial nitrogen inputs enhance coastal diatom production and shift nutrient limitation from nitrogen to silica, amplifying DA production. Surface particulate DA along the coast increases on average by

\sim

25% with anthropogenic inputs, suggesting a substantial enhancement of the region’s natural susceptibility to DA events. This study advances our ability to disentangle natural versus human drivers of Pseudo-nitzschia HABs, quantifying the role of anthropogenic inputs among the drivers of DA production in the Bight.

假硅藻属及其神经毒素软骨藻酸（DA）是美国西海岸有害藻华（HABs）的主要贡献者，影响海洋生态系统和人类健康。观测结果暗示了人为的养分输入、上升流和气候变率，但它们的相对重要性尚不清楚。我们将一个受培养实验约束的机械DA生产模型与一个三维海洋生物地球化学模型结合起来，模拟了拥有2300万人口的城市化地区南加州湾的DA循环。利用2006-2017年的1公里分辨率模拟，我们比较了两种情况：(i)人为情景（ANTH），其中河流和废水排放提供淡水并增强营养负荷，以及（ii）控制（CTRL），其中只有淡水通量，营养负荷设置为零。技能评估表明，ANTH捕获了观测到的季节模式、垂直分布和水平梯度。圣佩德罗和圣巴巴拉海峡的性能最高，但其他地方的性能较低，这表明需要改进以捕捉当地的赤潮动态。两个模拟结果的对比表明，陆地氮输入促进了海岸硅藻的生产，并将营养限制从氮转移到二氧化硅，放大了DA的生产。海岸带表面颗粒DA随人为输入平均增加~ 25%，表明该地区对DA事件的自然易感性显著增强。这项研究提高了我们对伪尼茨氏藻华的自然和人为驱动因素的理解能力，量化了人类输入在海洋中产生DA的驱动因素中的作用。

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引用次数: 0

Silencing of apoptotic gene caspase-2 enhances the susceptibility of a keystone aquatic grazer to cyanobacterial stress 凋亡基因caspase-2的沉默增强了关键水生食草动物对蓝藻胁迫的敏感性

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-11-17 DOI: 10.1016/j.hal.2025.103031

Tiantian Zheng, Xinyu Zhou, Linru Hao, Xinyu Zhang, Yiqin Ma, Yuzhou Hou, Kai Lyu, Zhou Yang

The increasing frequency of cyanobacterial blooms poses escalating ecological stress on freshwater ecosystems worldwide. These disturbances primarily act through impacts on basal trophic groups—most notably zooplankton. Apoptosis is a vital mechanism for preserving cellular homeostasis and managing stress at the organismal level, yet the role of its conserved regulators, such as caspase-2, remains poorly understood in aquatic grazers. We characterized a pivotal caspase-2 homolog in the freshwater water flea Moina macrocopa, an important model in aquatic ecology, and designated it Mm-cas2. Mm-cas2 possesses the characteristic caspase CASs domain, and phylogenetic analysis confirmed its classification within the caspase-2 family. Exposure to toxic Microcystis aeruginosa induced a dose-dependent increase in Mm-cas2 expression, confirmed at both mRNA (qRT-PCR) and protein (Western blot) levels. Spatial mapping via Whole-mount in situ hybridization (WISH) further indicated heterogeneous Mm-cas2 expression within the M. macrocopa organism. Critically, RNAi-mediated silencing of Mm-cas2 significantly heightened developmental retardation and reproductive obstruction in cyanobacteria-exposed M. macrocopa, confirming its essential role in governing sensitivity to M. aeruginosa. Our findings collectively reveal how the apoptotic regulator caspase-2 governs the sensitivity of M. macrocopa to M. aeruginosa, establishing Mm-cas2 as a candidate biomarker to evaluate ecological risks in freshwater ecosystems prone to cyanobacterial blooms outbreaks.

越来越频繁的蓝藻华对全球淡水生态系统造成了越来越大的生态压力。这些干扰主要通过对基础营养群的影响而起作用，最明显的是浮游动物。细胞凋亡是维持细胞稳态和在机体水平上管理应激的重要机制，但其保守的调节因子，如caspase-2，在水生食草动物中的作用仍然知之甚少。我们在水生生态学的重要模型淡水蚤Moina macrocopa中鉴定了一个关键的caspase-2同源物，并将其命名为Mm-cas2。Mm-cas2具有典型的caspase CASs结构域，系统发育分析证实其属于caspase-2家族。暴露于有毒的铜绿微囊藻诱导Mm-cas2表达的剂量依赖性增加，这在mRNA （qRT-PCR）和蛋白（Western blot）水平上得到证实。通过全安装原位杂交（WISH）的空间定位进一步表明，Mm-cas2在M. macrocopa生物体内的表达具有异质性。关键的是，rnai介导的Mm-cas2沉默显著增加了蓝藻暴露的巨巨假单胞菌的发育迟缓和生殖障碍，证实了其在控制对铜绿假单胞菌的敏感性方面的重要作用。我们的研究结果共同揭示了凋亡调节因子caspase-2如何控制M. macrocopa对M. aeruginosa的敏感性，建立了Mm-cas2作为评估淡水生态系统中容易发生蓝藻爆发的生态风险的候选生物标志物。

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引用次数: 0

Melatonin promotes dinoflagellate cyst germination by crosstalk with abscisic acid and gibberellin 褪黑素通过与脱落酸和赤霉素的串扰促进鞭毛囊萌发

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-11-15 DOI: 10.1016/j.hal.2025.103030

Caixia Yue , Yunyan Deng , Fengting Li , Zhaoyang Chai , Zhe Tao , Lixia Shang , Ying Zhong Tang

Dinoflagellates play pivotal roles in marine ecosystems, particularly as major contributors to marine harmful algal blooms (HABs). Their resting cysts, analogous to higher plant seeds, directly regulate seasonal population dynamics and initiate HABs through germination. The phytohormone Melatonin (MEL) has been widely documented to regulate seed germination in higher plants. This study investigated the effect of exogenously-added MEL on the germination of dinoflagellate resting cyst assemblage isolated from marine sediment and its possible interplay with two other dormancy-related phytohormones (abscisic acid, ABA, and gibberellic acid, GA3) in regulating germination of cysts both from sediment and the representative cyst-producing dinoflagellate Scrippsiella acuminata. Exogenous addition assays revealed that while MEL significantly inhibited cyst germination when concentrations >100 μM, it enhanced cyst germination dose-dependently within 1.0–8.0 μM. MEL antagonized ABA in regulating cyst germination and repressing ABA biosynthesis genes but up-regulating ABA catabolic genes. However, MEL synergized with GA3 in promoting germination by enhancing GA biosynthesis and via induction of GA receptor. All results collectively suggest MEL promotes dinoflagellate cyst germination by crosstalk with ABA and GA3, and these phytohormones in protists play roles similar to that in higher plants. Our study provides novel evidences for the regulating roles and mechanisms of MEL.

鞭毛藻在海洋生态系统中发挥着关键作用，特别是作为海洋有害藻华（HABs）的主要贡献者。它们的休眠包囊类似于高等植物的种子，直接调节季节种群动态，并通过萌发启动有害藻华。植物激素褪黑素（MEL）在高等植物中调控种子萌发已被广泛报道。本研究研究了外源添加MEL对海洋沉积物中鞭毛藻休眠囊群萌发的影响，以及它与其他两种与休眠相关的植物激素（脱落酸ABA和赤霉素GA3）在调节沉积物和具有代表性的囊生成鞭毛藻尖棘草囊群萌发中的可能相互作用。外源添加实验表明，当浓度为100 μM时，MEL显著抑制包囊萌发，但在1.0 ~ 8.0 μM范围内，MEL促进包囊萌发呈剂量依赖性。MEL拮抗ABA调控囊肿萌发，抑制ABA生物合成基因，上调ABA分解代谢基因。然而，MEL与GA3协同作用，通过促进GA生物合成和诱导GA受体促进萌发。综上所述，MEL通过与ABA和GA3的串扰促进鞭毛藻包囊萌发，这些激素在原生生物中的作用与高等植物相似。本研究为MEL的调控作用和机制提供了新的证据。

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引用次数: 0