Harmful Algae最新文献_第9页

Responses of a harmful algal bloom-causing dinoflagellate Prorocentrum obtusidens to elevated temperature and urea 引起藻华的鞭毛原藻对高温和尿素的反应

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-08-24 DOI: 10.1016/j.hal.2025.102958

Wei-Ping Zhang , Yang Zhou , Wen-Jing Sun , Shuo-Yu Zhang , Shu-Feng Zhang , Jae-Seong Lee , Minghua Wang , Da-Zhi Wang

Elevated temperature and nitrogen (N) availability affect dinoflagellates differently; however, their interactive effects remain largely unexplored. This study investigated the physiological and transcriptomic responses of a harmful algal bloom-causing dinoflagellate, Prorocentrum obtusidens, to elevated temperature (22 °C vs. 26 °C) under three N conditions (16 μM nitrate, 8 and 16 μM urea) after 32 days of exposure. Elevated temperature enhanced cell growth across all N conditions, with a more pronounced increase in urea-grown cells, regardless of the insignificant interaction between temperature and N. Physiological responses to elevated temperature varied under N conditions. The nitrate-grown cells had higher particulate organic carbon (POC) content, C:N ratio, and activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), phosphoenolpyruvate carboxykinase, and urease, but lower particulate organic N (PON) content. The low urea-grown cells showed higher C:N ratio, total carbohydrate content, and activities of carbonic anhydrase (CA), glutamine synthetase (GS), and urease, but lower phosphoenolpyruvate carboxylase activity, total protein, and total antioxidant capacity. The high urea-grown cells exhibited higher maximum photosynthetic efficiency, POC content, C:N ratio, and activities of CA, RubisCO, GS, and urease. Transcriptomic analysis revealed that elevated temperature increased the expression of genes associated with photosynthesis under all N conditions. The nitrate-grown cells produced more energy to mitigate thermal stress, whereas the urea-grown cells decreased energy production. These findings suggest that P. obtusidens is more resilient to future ocean warming when grown with urea, and predictions of dinoflagellate responses to warming oceans should consider N conditions in the environment.

升高的温度和氮(N)有效性对鞭毛藻的影响不同；然而，它们的相互作用在很大程度上仍未被探索。本研究研究了在3种N浓度（16 μM硝酸盐、8和16 μM尿素）条件下，对22°C和26°C的高温（22°C和26°C）暴露32天后的生理和转录组反应。在所有的N条件下，升高的温度都促进了细胞的生长，尽管温度和N之间的相互作用不明显，但尿素生长的细胞的增长更为明显。硝酸盐培养的细胞颗粒有机碳（POC）含量、碳氮比、核酮糖-1,5-二磷酸羧化酶/加氧酶（RubisCO）、磷酸烯醇丙酮酸羧激酶和脲酶活性较高，颗粒有机氮（PON）含量较低。低尿素培养的细胞C:N比、总碳水化合物含量、碳酸酐酶（CA）、谷氨酰胺合成酶（GS）和脲酶活性较高，但磷酸烯醇丙酮酸羧化酶活性、总蛋白和总抗氧化能力较低。高尿素培养的细胞表现出更高的最大光合效率、POC含量、C:N比以及CA、RubisCO、GS和脲酶活性。转录组学分析显示，在所有氮条件下，温度升高均增加了光合作用相关基因的表达。硝酸盐生长的细胞产生更多的能量来缓解热应激，而尿素生长的细胞则减少能量产生。这些发现表明，当与尿素一起生长时，P. obtusidens对未来海洋变暖的适应能力更强，并且预测鞭毛藻对变暖海洋的反应应考虑环境中的N条件。

{"title":"Responses of a harmful algal bloom-causing dinoflagellate Prorocentrum obtusidens to elevated temperature and urea","authors":"Wei-Ping Zhang , Yang Zhou , Wen-Jing Sun , Shuo-Yu Zhang , Shu-Feng Zhang , Jae-Seong Lee , Minghua Wang , Da-Zhi Wang","doi":"10.1016/j.hal.2025.102958","DOIUrl":"10.1016/j.hal.2025.102958","url":null,"abstract":"<div><div>Elevated temperature and nitrogen (N) availability affect dinoflagellates differently; however, their interactive effects remain largely unexplored. This study investigated the physiological and transcriptomic responses of a harmful algal bloom-causing dinoflagellate, <em>Prorocentrum obtusidens</em>, to elevated temperature (22 °C vs. 26 °C) under three N conditions (16 μM nitrate, 8 and 16 μM urea) after 32 days of exposure. Elevated temperature enhanced cell growth across all N conditions, with a more pronounced increase in urea-grown cells, regardless of the insignificant interaction between temperature and N. Physiological responses to elevated temperature varied under N conditions. The nitrate-grown cells had higher particulate organic carbon (POC) content, C:N ratio, and activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), phosphoenolpyruvate carboxykinase, and urease, but lower particulate organic N (PON) content. The low urea-grown cells showed higher C:N ratio, total carbohydrate content, and activities of carbonic anhydrase (CA), glutamine synthetase (GS), and urease, but lower phosphoenolpyruvate carboxylase activity, total protein, and total antioxidant capacity. The high urea-grown cells exhibited higher maximum photosynthetic efficiency, POC content, C:N ratio, and activities of CA, RubisCO, GS, and urease. Transcriptomic analysis revealed that elevated temperature increased the expression of genes associated with photosynthesis under all N conditions. The nitrate-grown cells produced more energy to mitigate thermal stress, whereas the urea-grown cells decreased energy production. These findings suggest that <em>P. obtusidens</em> is more resilient to future ocean warming when grown with urea, and predictions of dinoflagellate responses to warming oceans should consider N conditions in the environment.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"149 ","pages":"Article 102958"},"PeriodicalIF":4.5,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144912873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Sargassum transport to the Amazon Coast: Explaining the stranding through meteorological and oceanographic conditions 马尾藻运输到亚马逊海岸：通过气象和海洋学条件解释搁浅

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-08-23 DOI: 10.1016/j.hal.2025.102955

João Pedro Mancio de Amorim , Alexandre Melo Casseb do Carmo , José Eduardo Martinelli Filho

Over the recent years, different areas around the tropical Atlantic Ocean experienced an increase in pelagic Sargassum stranding events. Such incidents pose ecological and socioeconomic challenges, since they are difficult to predict and can impact coastal communities. In this study, we investigate the physical mechanisms behind Sargassum stranding events on the Brazilian Amazon Coast, focusing on the northeastern Pará region (northern Brazil), especially during the sporadic massive events registered in May 2014, April 2015, March 2019 and March 2025. We used a combination of observational data, reanalysis, forecast products, and Lagrangian experiments to explore the role of meteorological and oceanographic conditions during the occurrence of the strandings. Our results suggest that the events are related to the rainy season, when the Intertropical Convergence Zone (ITCZ) is positioned at its southernmost extent, bringing intense rainfall and northeasterly winds to the region. These winds can increase the landward transport of floating particles into the Amazon Continental Shelf (ACS). The results from the Lagrangian simulations highlighted the importance of wind drag and local processes (i.e., tidal currents and Stokes drift) in promoting the intrusion of floating particles into the inner shelf, particularly in the northeastern sector of the ACS, which emerges as a preferential pathway for the entrance of offshore Sargassum patches. This pathway was also highlighted by the sighting of Sargassum close to this area prior to the massive event of 2025, reinforcing the role of winds and tidal currents in connecting the northeastern offshore sector of ACS to the coast. While global reanalysis products and forecast systems provided valuable insights, future research should focus on the implementation of regional models to provide more accurate predictions near the coast, improving predictive capabilities to mitigate the impacts of these phenomena.

近年来，热带大西洋周围的不同地区经历了上层马尾藻搁浅事件的增加。此类事件带来了生态和社会经济挑战，因为它们难以预测，并可能影响沿海社区。在这项研究中，我们研究了巴西亚马逊海岸马尾藻搁浅事件背后的物理机制，重点研究了par东北部地区（巴西北部），特别是在2014年5月、2015年4月、2019年3月和2025年3月记录的零星大规模事件期间。我们采用观测资料、再分析、预报产品和拉格朗日实验相结合的方法，探讨了气象和海洋条件在搁浅发生过程中的作用。结果表明，这些事件与雨季有关，此时热带辐合带（ITCZ）位于其最南端，为该地区带来强降雨和东北风。这些风可以增加漂浮粒子向陆地输送到亚马逊大陆架（ACS）。拉格朗日模拟的结果强调了风阻和局部过程（即潮汐流和斯托克斯漂移）在促进漂浮粒子侵入内大陆架方面的重要性，特别是在ACS的东北部分，这是近海马尾藻斑块进入的优先途径。在2025年的大规模事件发生之前，在该地区附近发现了马尾藻，这也突出了这条路径，加强了风和潮流在连接ACS东北近海地区和海岸方面的作用。虽然全球再分析产品和预测系统提供了有价值的见解，但未来的研究应侧重于实施区域模型，以便在海岸附近提供更准确的预测，提高预测能力，以减轻这些现象的影响。

{"title":"Sargassum transport to the Amazon Coast: Explaining the stranding through meteorological and oceanographic conditions","authors":"João Pedro Mancio de Amorim , Alexandre Melo Casseb do Carmo , José Eduardo Martinelli Filho","doi":"10.1016/j.hal.2025.102955","DOIUrl":"10.1016/j.hal.2025.102955","url":null,"abstract":"<div><div>Over the recent years, different areas around the tropical Atlantic Ocean experienced an increase in pelagic <em>Sargassum</em> stranding events. Such incidents pose ecological and socioeconomic challenges, since they are difficult to predict and can impact coastal communities. In this study, we investigate the physical mechanisms behind <em>Sargassum</em> stranding events on the Brazilian Amazon Coast, focusing on the northeastern Pará region (northern Brazil), especially during the sporadic massive events registered in May 2014, April 2015, March 2019 and March 2025. We used a combination of observational data, reanalysis, forecast products, and Lagrangian experiments to explore the role of meteorological and oceanographic conditions during the occurrence of the strandings. Our results suggest that the events are related to the rainy season, when the Intertropical Convergence Zone (ITCZ) is positioned at its southernmost extent, bringing intense rainfall and northeasterly winds to the region. These winds can increase the landward transport of floating particles into the Amazon Continental Shelf (ACS). The results from the Lagrangian simulations highlighted the importance of wind drag and local processes (<em>i.e.</em>, tidal currents and Stokes drift) in promoting the intrusion of floating particles into the inner shelf, particularly in the northeastern sector of the ACS, which emerges as a preferential pathway for the entrance of offshore <em>Sargassum</em> patches. This pathway was also highlighted by the sighting of <em>Sargassum</em> close to this area prior to the massive event of 2025, reinforcing the role of winds and tidal currents in connecting the northeastern offshore sector of ACS to the coast. While global reanalysis products and forecast systems provided valuable insights, future research should focus on the implementation of regional models to provide more accurate predictions near the coast, improving predictive capabilities to mitigate the impacts of these phenomena.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"149 ","pages":"Article 102955"},"PeriodicalIF":4.5,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144908900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Walruses are potentially exposed to paralytic shellfish toxin concentrations that impact their health during Alexandrium blooms in the Alaskan Arctic 在阿拉斯加北极的亚历山大藻繁盛期间，海象可能暴露于麻痹性贝类毒素浓度，影响它们的健康

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-08-23 DOI: 10.1016/j.hal.2025.102960

Patrick Charapata , Evangeline Fachon , Donald M. Anderson , Gay Sheffield , Emily K. Bowers , Robert S. Pickart , Peigen Lin , Kathi A. Lefebvre

Harmful algal bloom (HAB) activity of Alexandrium catenella, a dinoflagellate that produces paralytic shellfish toxins (PSTs), has increased in the Alaskan Arctic due to warming ocean conditions. Arctic wildlife exposure to PSTs due to these blooms remains unknown. The Pacific walrus (Odobenus rosmarus divergens) is a marine mammal that preys primarily on efficient vectors of PSTs (benthic invertebrates), making walruses an important model for assessing PST exposure risks. Here, we used paired Alexandrium data (Alexandrium cell and cyst densities and PST content), and PSTs measured in benthic invertebrates (clams, worms, and gastropods) to construct and validate trophic transfer models of PSTs in a critical Arctic food chain. Further, we used observed PSTs in walrus prey to estimate daily walrus oral PST doses (µg STX eq. kg^-1) during summers (2019 and 2022) with well-characterized and widespread Alexandrium blooms. Models were validated using various model metrics, however, predictions underestimated toxicity (STX eq.) of invertebrates. Observed PSTs in walrus prey resulted in 89 % (n = 47 of 53 total; 2019) and 67 % (n = 41 of 61; 2022) of PST doses exceeding thresholds posing a moderate health risk to walruses (> 11.6 μg STX eq. kg^-1). Ledyard Bay in the northeastern Chukchi Sea was identified as a PST exposure risk hotspot because it contained the highest estimated doses, while walruses simultaneously occupied the neighboring Point Lay haulout. Additional studies are required to assess how HAB activity will impact walrus health as well as food-security and food-safety for Indigenous communities that rely on walruses for subsistence.

由于海洋环境变暖，阿拉斯加北极地区有害藻华（HAB）活动增加，这是一种产生麻痹性贝类毒素（PSTs）的双鞭毛藻。北极野生动物因这些水华而暴露于pst的情况尚不清楚。太平洋海象（Odobenus rosmarus divergens）是一种主要捕食PST（底栖无脊椎动物）有效载体的海洋哺乳动物，使海象成为评估PST暴露风险的重要模型。在这里，我们使用了配对的亚历山大菌数据（亚历山大菌细胞和囊密度以及PST含量），并在底栖无脊椎动物（蛤蜊、蠕虫和腹足类）中测量了PST，以构建和验证PST在北极关键食物链中的营养转移模型。此外，我们使用海象猎物中观察到的PST来估计海象在夏季（2019年和2022年）的每日口服PST剂量（µg STX = kg-1），其中亚历山大菌大量繁殖。使用各种模型指标验证了模型，然而，预测低估了无脊椎动物的毒性（STX eq.）。在海象猎物中观察到的PST导致89% （n = 47 / 53; 2019）和67% （n = 41 / 61; 2022）的PST剂量超过对海象构成中等健康风险的阈值（> 11.6 μg STX = kg-1）。楚科奇海东北部的Ledyard湾被确定为PST暴露风险热点，因为它含有最高的估计剂量，而海象同时占据了邻近的Point Lay港口。需要进一步的研究来评估有害藻华活动将如何影响海象的健康以及依赖海象为生的土著社区的粮食安全和食品安全。

{"title":"Walruses are potentially exposed to paralytic shellfish toxin concentrations that impact their health during Alexandrium blooms in the Alaskan Arctic","authors":"Patrick Charapata , Evangeline Fachon , Donald M. Anderson , Gay Sheffield , Emily K. Bowers , Robert S. Pickart , Peigen Lin , Kathi A. Lefebvre","doi":"10.1016/j.hal.2025.102960","DOIUrl":"10.1016/j.hal.2025.102960","url":null,"abstract":"<div><div>Harmful algal bloom (HAB) activity of <em>Alexandrium catenella</em>, a dinoflagellate that produces paralytic shellfish toxins (PSTs), has increased in the Alaskan Arctic due to warming ocean conditions. Arctic wildlife exposure to PSTs due to these blooms remains unknown. The Pacific walrus (<em>Odobenus rosmarus divergens</em>) is a marine mammal that preys primarily on efficient vectors of PSTs (benthic invertebrates), making walruses an important model for assessing PST exposure risks. Here, we used paired <em>Alexandrium</em> data (<em>Alexandrium</em> cell and cyst densities and PST content), and PSTs measured in benthic invertebrates (clams, worms, and gastropods) to construct and validate trophic transfer models of PSTs in a critical Arctic food chain. Further, we used observed PSTs in walrus prey to estimate daily walrus oral PST doses (µg STX eq. kg<sup>-1</sup>) during summers (2019 and 2022) with well-characterized and widespread <em>Alexandrium</em> blooms. Models were validated using various model metrics, however, predictions underestimated toxicity (STX eq.) of invertebrates. Observed PSTs in walrus prey resulted in 89 % (<em>n</em> <em>=</em> 47 of 53 total; 2019) and 67 % (<em>n</em> <em>=</em> 41 of 61; 2022) of PST doses exceeding thresholds posing a moderate health risk to walruses (> 11.6 μg STX eq. kg<sup>-1</sup>). Ledyard Bay in the northeastern Chukchi Sea was identified as a PST exposure risk hotspot because it contained the highest estimated doses, while walruses simultaneously occupied the neighboring Point Lay haulout. Additional studies are required to assess how HAB activity will impact walrus health as well as food-security and food-safety for Indigenous communities that rely on walruses for subsistence.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"149 ","pages":"Article 102960"},"PeriodicalIF":4.5,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144912872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Climate change will boost the invasion of the harmful cyanobacterium Raphidiopsis raciborskii in South America 气候变化将促进有害蓝藻Raphidiopsis raciborskii在南美洲的入侵

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-08-21 DOI: 10.1016/j.hal.2025.102957

Felipe Morais Zanon , Bruno Henrique Mioto Stabile , Beatriz Melissa Campos , Érica Oliveira de Lima , Matheus Juan Alarcon Sampaio , Yasmin Rodrigues de Souza , Leonardo Rodrigues Tolardo , Mayra Koma Gomes , Luddy Searom Carias de Moraes , Gabriela Sponchiado Hein , Jaqueline Dantas da Silva , Larissa da Silva Pinha , Loiani Oliveira Santana , Mariana Albuquerque , Vinicius da Silva , João Vitor Bredariol , Gabriel Arthur Lopes da Silva , Gabriel Delabio da Silva , Aline Aparecida Aguiar Ferreira , Luíz Fernando Esser , Luzia Cleide Rodrigues

The invasive cyanobacterium species Raphidiopsis raciborskii was first recorded in the Indo-Malaysian region in 1899, and studies currently report its presence in tropical, subtropical, and temperate environments around the world. In addition to its plasticity in colonizing new environments, R. raciborskii deserves attention for its ability to produce saxitoxin and cylindrospermopsin, which can cause the death of aquatic organisms and harm human health. In this work, we assessed the effect of global climate change towards the end of this century on the potential expansion of R. raciborskii using ecological niche models (ENMs). We applied a set of machine learning algorithms within the ensemble prediction approach to estimate the potential distribution of the species in South America under projected climate change, considering different carbon emission scenarios. In the moderate scenario, the northern Amazon basin, the southern Orinoco basin, and part of the North Atlantic basin showed increased environmental suitability for the species. In the pessimistic scenario, the basin with the greatest increase in suitability was the Paraná-Paraguay basin. Several basins remained highly suitable in both current and future scenarios, especially in Brazil. This study highlights the importance of understanding and addressing the impacts of climate change on the distribution of the invasive species R. raciborskii. South American countries must implement monitoring measures to assess the expansion of blooms of this species, as well as government actions to control water quality, given the strong impact of these organisms on biodiversity and ecosystem services.

入侵蓝藻物种Raphidiopsis raciborskii于1899年首次在印度-马来西亚地区被记录，目前研究报告它在世界各地的热带、亚热带和温带环境中都有存在。除了在新环境中具有可塑性外，raciborskii还具有产生蛤蚌毒素和柱精子素的能力，这些物质会导致水生生物死亡，危害人类健康，值得关注。本研究利用生态位模型（ENMs）评估了本世纪末全球气候变化对鼠耳鼠潜在扩张的影响。我们在集合预测方法中应用了一套机器学习算法来估计在预测的气候变化下南美洲物种的潜在分布，考虑不同的碳排放情景。在中等情景下，亚马逊盆地北部、奥里诺科河盆地南部和北大西洋盆地的部分地区对该物种的环境适应性增强。在悲观情景下，适宜性增加最大的盆地为Paraná-Paraguay盆地。在当前和未来的情况下，几个盆地仍然非常适合，尤其是巴西。本研究强调了认识和解决气候变化对入侵物种鼠唇蝗分布的影响的重要性。鉴于这些生物对生物多样性和生态系统服务的巨大影响，南美国家必须实施监测措施，以评估该物种繁殖的扩大，以及政府控制水质的行动。

{"title":"Climate change will boost the invasion of the harmful cyanobacterium Raphidiopsis raciborskii in South America","authors":"Felipe Morais Zanon , Bruno Henrique Mioto Stabile , Beatriz Melissa Campos , Érica Oliveira de Lima , Matheus Juan Alarcon Sampaio , Yasmin Rodrigues de Souza , Leonardo Rodrigues Tolardo , Mayra Koma Gomes , Luddy Searom Carias de Moraes , Gabriela Sponchiado Hein , Jaqueline Dantas da Silva , Larissa da Silva Pinha , Loiani Oliveira Santana , Mariana Albuquerque , Vinicius da Silva , João Vitor Bredariol , Gabriel Arthur Lopes da Silva , Gabriel Delabio da Silva , Aline Aparecida Aguiar Ferreira , Luíz Fernando Esser , Luzia Cleide Rodrigues","doi":"10.1016/j.hal.2025.102957","DOIUrl":"10.1016/j.hal.2025.102957","url":null,"abstract":"<div><div>The invasive cyanobacterium species <em>Raphidiopsis raciborskii</em> was first recorded in the Indo-Malaysian region in 1899, and studies currently report its presence in tropical, subtropical, and temperate environments around the world. In addition to its plasticity in colonizing new environments, <em>R. raciborskii</em> deserves attention for its ability to produce saxitoxin and cylindrospermopsin, which can cause the death of aquatic organisms and harm human health. In this work, we assessed the effect of global climate change towards the end of this century on the potential expansion of <em>R. raciborskii</em> using ecological niche models (ENMs). We applied a set of machine learning algorithms within the ensemble prediction approach to estimate the potential distribution of the species in South America under projected climate change, considering different carbon emission scenarios. In the moderate scenario, the northern Amazon basin, the southern Orinoco basin, and part of the North Atlantic basin showed increased environmental suitability for the species. In the pessimistic scenario, the basin with the greatest increase in suitability was the Paraná-Paraguay basin. Several basins remained highly suitable in both current and future scenarios, especially in Brazil. This study highlights the importance of understanding and addressing the impacts of climate change on the distribution of the invasive species <em>R. raciborskii</em>. South American countries must implement monitoring measures to assess the expansion of blooms of this species, as well as government actions to control water quality, given the strong impact of these organisms on biodiversity and ecosystem services.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"149 ","pages":"Article 102957"},"PeriodicalIF":4.5,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144895575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

First report of nodularin production by Nostochopsis sp. in a temperate eutrophic lake 温带富营养化湖泊Nostochopsis sp.产生结核素的首次报道

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-08-19 DOI: 10.1016/j.hal.2025.102956

Abby M. Webster , Zac Triumph , Bofan Wei , Robbie M. Martin , Laura E. Smith , Steven W. Wilhelm , Lisa B. Cleckner , N.Roxanna Razavi , Gregory L. Boyer

Benthic cyanobacteria are understudied in comparison to their planktonic counterparts. Consequently, our understanding of cyanotoxin production in benthic mats remains limited. We detected nodularin-R (NOD-R) in a population of Nostochopsis from Honeoye Lake (New York, United States). Identification as Nostochopsis was supported by morphological (see section 3.1 for a detailed description) and metagenomic analyses. The first metagenome assembled genome of Nostochopsis was drafted and estimated at 99.28 % complete. Cyanotoxin testing of Nostochopsis biomass showed production of NOD-R but not microcystins, anatoxins, or cylindrospermopsins. The complete nodularin synthetase cluster was confirmed in the Nostochopsis genome. To our knowledge, this is the first report of nodularin production, or any cyanotoxin production, by the benthic cyanobacteria Nostochopsis. This is the fourth genus of cyanobacteria reported to produce nodularins.

与浮游生物相比，底栖蓝藻的研究不足。因此，我们对底栖垫中蓝藻毒素产生的了解仍然有限。我们在来自美国纽约Honeoye Lake的Nostochopsis种群中检测到了结节素r （nodarin - r）。形态学（详细描述见3.1节）和宏基因组学分析支持了该菌株的Nostochopsis鉴定。绘制了首个Nostochopsis元基因组组装基因组，估计完成度为99.28%。蓝藻毒素测试表明，蓝藻生物量产生NOD-R，但不产生微囊藻毒素、anatoxins或圆筒精子蛋白酶。完整的结核素合成酶簇在结核杆菌基因组中得到证实。据我们所知，这是第一个报告结核素生产，或任何蓝藻毒素生产，由底栖蓝藻菌Nostochopsis。这是第四个据报道产生结核杆菌的蓝藻属。

{"title":"First report of nodularin production by Nostochopsis sp. in a temperate eutrophic lake","authors":"Abby M. Webster , Zac Triumph , Bofan Wei , Robbie M. Martin , Laura E. Smith , Steven W. Wilhelm , Lisa B. Cleckner , N.Roxanna Razavi , Gregory L. Boyer","doi":"10.1016/j.hal.2025.102956","DOIUrl":"10.1016/j.hal.2025.102956","url":null,"abstract":"<div><div>Benthic cyanobacteria are understudied in comparison to their planktonic counterparts. Consequently, our understanding of cyanotoxin production in benthic mats remains limited. We detected nodularin-R (NOD-R) in a population of <em>Nostochopsis</em> from Honeoye Lake (New York, United States). Identification as <em>Nostochopsis</em> was supported by morphological (see section 3.1 for a detailed description) and metagenomic analyses. The first metagenome assembled genome of <em>Nostochopsis</em> was drafted and estimated at 99.28 % complete. Cyanotoxin testing of <em>Nostochopsis</em> biomass showed production of NOD-R but not microcystins, anatoxins, or cylindrospermopsins. The complete nodularin synthetase cluster was confirmed in the <em>Nostochopsis</em> genome. To our knowledge, this is the first report of nodularin production, or any cyanotoxin production, by the benthic cyanobacteria <em>Nostochopsis</em>. This is the fourth genus of cyanobacteria reported to produce nodularins.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"149 ","pages":"Article 102956"},"PeriodicalIF":4.5,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Seasonal and regional variability of lipophilic marine phycotoxins in eutrophic coastal waters of the South China Sea 南海富营养化沿海水域亲脂藻毒素的季节和区域变异

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-08-18 DOI: 10.1016/j.hal.2025.102954

Min Liu , Liyan Deng , Yan Wang , Xiaodong Wang , Sen Du , Zhicai She , Zhenjun Kang , Qingxia Liu , Peng Wu , Zexing Kuang , Lingxiang Zhu , Jiajun Wu , Lai Leo Chan , Yuanyue Cheng , Li Zhang , Yang Liu

Lipophilic marine phycotoxins (LMTs), primarily produced by toxigenic dinoflagellates, pose significant risks to marine ecosystems and human health due to their toxicity and widespread distribution. This study investigates the spatial and temporal distribution of LMTs in the surface seawater from representative estuarine and bay areas of the South China Sea (SCS) during period from 2022‒2023. Using active solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry (Active-SPE-LC-MS/MS), the study revealed that significantly higher LMTs concentrations in semi-enclosed bays (13.15 ± 8.61 ng L⁻¹) compared to estuarine regions (8.55 ± 8.59 ng L⁻¹), with Daya Bay (DB) and Jian River Estuary (JRE) exhibiting the highest toxin levels. The most prevalent toxins were diarrhetic shellfish toxins (OA, DTX1) and pectenotoxin-2 (PTX2), with PTX2 being dominant in most regions. Seasonal variations were evident, with higher LMTs concentrations observed during the wet season, particularly in spring and summer. Principal component analysis (PCA) revealed distinct toxin profiles, with PTX2, GYM, and OA being prevalent in the Pearl River Estuary (PRE), while AZA2 and DTX1 were more abundant in Qinzhou Bay (QB). The study highlights the influence of local environmental conditions, such as seasonal and region variations on LMTs distribution. These findings provide critical insights into the ecological dynamics of LMTs in eutrophic coastal waters, emphasizing the need for continuous monitoring to mitigate risks to marine ecosystems and human health. This research contributes to a deeper understanding of LMTs distribution patterns in the SCS, supporting future risk assessments and management strategies.

亲脂性海洋藻毒素（lmt）主要由产毒鞭毛藻产生，由于其毒性和广泛分布，对海洋生态系统和人类健康构成重大风险。研究了2022-2023年南海代表性河口湾区表层海水中lmt的时空分布特征。采用活性固相萃取-液相色谱-串联质谱联用技术（active - spe - lc -MS/MS）研究发现，半封闭海湾地区的毒素浓度（13.15±8.61 ng L−1）显著高于河口地区（8.55±8.59 ng L−1），其中大亚湾（DB）和剑江口（JRE）的毒素含量最高。最常见的毒素是腹泻性贝类毒素（OA、DTX1）和果皮毒素-2 (PTX2)，大部分地区以PTX2为主。季节变化明显，在雨季，特别是春季和夏季，观察到的LMTs浓度较高。主成分分析显示，珠江口（PRE）以PTX2、GYM和OA为主，而钦州湾（QB）以AZA2和DTX1为主。该研究强调了当地环境条件（如季节和区域变化）对LMTs分布的影响。这些发现为富营养化沿海水域中浮游生物的生态动态提供了重要见解，强调需要持续监测以减轻对海洋生态系统和人类健康的风险。这项研究有助于更深入地了解南中国海的LMTs分布模式，为未来的风险评估和管理策略提供支持。

{"title":"Seasonal and regional variability of lipophilic marine phycotoxins in eutrophic coastal waters of the South China Sea","authors":"Min Liu , Liyan Deng , Yan Wang , Xiaodong Wang , Sen Du , Zhicai She , Zhenjun Kang , Qingxia Liu , Peng Wu , Zexing Kuang , Lingxiang Zhu , Jiajun Wu , Lai Leo Chan , Yuanyue Cheng , Li Zhang , Yang Liu","doi":"10.1016/j.hal.2025.102954","DOIUrl":"10.1016/j.hal.2025.102954","url":null,"abstract":"<div><div>Lipophilic marine phycotoxins (LMTs), primarily produced by toxigenic dinoflagellates, pose significant risks to marine ecosystems and human health due to their toxicity and widespread distribution. This study investigates the spatial and temporal distribution of LMTs in the surface seawater from representative estuarine and bay areas of the South China Sea (SCS) during period from 2022‒2023. Using active solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry (Active-SPE-LC-MS/MS), the study revealed that significantly higher LMTs concentrations in semi-enclosed bays (13.15 ± 8.61 ng L<sup>−1</sup>) compared to estuarine regions (8.55 ± 8.59 ng L<sup>−1</sup>), with Daya Bay (DB) and Jian River Estuary (JRE) exhibiting the highest toxin levels. The most prevalent toxins were diarrhetic shellfish toxins (OA, DTX1) and pectenotoxin-2 (PTX2), with PTX2 being dominant in most regions. Seasonal variations were evident, with higher LMTs concentrations observed during the wet season, particularly in spring and summer. Principal component analysis (PCA) revealed distinct toxin profiles, with PTX2, GYM, and OA being prevalent in the Pearl River Estuary (PRE), while AZA2 and DTX1 were more abundant in Qinzhou Bay (QB). The study highlights the influence of local environmental conditions, such as seasonal and region variations on LMTs distribution. These findings provide critical insights into the ecological dynamics of LMTs in eutrophic coastal waters, emphasizing the need for continuous monitoring to mitigate risks to marine ecosystems and human health. This research contributes to a deeper understanding of LMTs distribution patterns in the SCS, supporting future risk assessments and management strategies.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"149 ","pages":"Article 102954"},"PeriodicalIF":4.5,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144895536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Genotypic diversity and growth responses to temperature and salinity variations of Coolia malayensis (Gonyaulacales, Dinophyceae) in Chinese coastal waters 中国沿海海域马来Coolia malayensis （Gonyaulacales, Dinophyceae）基因型多样性及其对温度和盐度变化的生长响应

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-08-14 DOI: 10.1016/j.hal.2025.102945

Ruoyu Guo , Xu-Dong Lian , Ruifang Wang , Yue Jiang , Sungmo Kang , Chenjie Zhu , Xiao Ma , Shiwen Zhou , Leo Lai Chan , Xinfeng Dai , Pengbin Wang , Zhun Li

Coolia malayensis is a benthic dinoflagellate widely distributed in tropical to subtropical coastal waters, with some strains exhibiting cytotoxicity, indicating potential ecological and toxicological roles. This study investigated the genetic diversity and adaptability of C. malayensis strains across diverse environmental conditions in Chinese coastal waters. Three distinct genotypes, Genotype 1 (strain DF553), Genotype 2 (DF630), and Genotype 3 comprising strains DF307, DF316, and DF364, were confirmed by the large subunit (LSU) ribosomal DNA phylogenetic analysis, with a protein profiling by the matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry providing supporting evidence for the phenotypic differentiations. The results of growth experiments conducted under varying temperature (15°C to 30°C) and salinity (15 to 35) conditions demonstrated genotype-specific environmental preferences: strain DF553 exhibited an optimal growth at 25°C and 30 salinity, strain DF630 at 30°C and 30, while strains DF307, DF316, and DF364 displayed a wider range of adaptive capacities. These results emphasized the ecological flexibility and adaptive potential of C. malayensis, indicating its ability to thrive in diverse marine environments. The study underscores the importance of genotypic variation in predicting species responses to environmental fluctuations, offering valuable insights for marine ecosystem management and mitigation of harmful algal blooms.

马来西亚Coolia malayensis是一种广泛分布于热带至亚热带沿海水域的底栖鞭毛藻，其中一些菌株表现出细胞毒性，表明潜在的生态和毒理学作用。本研究研究了中国沿海不同环境条件下马来酸盐（C. malayensis）菌株的遗传多样性和适应性。基因1型（DF553）、基因2型（DF630）和基因3型（DF307、DF316和DF364）由LSU核糖体DNA系统发育分析证实，基质辅助激光脱附/电离飞行时间（MALDI-TOF）质谱的蛋白质谱图为表型分化提供了支持证据。在不同温度（15°C ~ 30°C）和盐度（15 ~ 35）条件下进行的生长实验结果显示了基因型特异性的环境偏好：菌株DF553在25°C和30盐度下表现出最佳生长，菌株DF630在30°C和30盐度下表现出最佳生长，而菌株DF307、DF316和DF364表现出更广泛的适应能力。这些结果强调了马来刺槐的生态灵活性和适应潜力，表明其能够在不同的海洋环境中茁壮成长。该研究强调了基因型变异在预测物种对环境波动的反应方面的重要性，为海洋生态系统管理和减轻有害藻华提供了有价值的见解。

{"title":"Genotypic diversity and growth responses to temperature and salinity variations of Coolia malayensis (Gonyaulacales, Dinophyceae) in Chinese coastal waters","authors":"Ruoyu Guo , Xu-Dong Lian , Ruifang Wang , Yue Jiang , Sungmo Kang , Chenjie Zhu , Xiao Ma , Shiwen Zhou , Leo Lai Chan , Xinfeng Dai , Pengbin Wang , Zhun Li","doi":"10.1016/j.hal.2025.102945","DOIUrl":"10.1016/j.hal.2025.102945","url":null,"abstract":"<div><div><em>Coolia malayensis</em> is a benthic dinoflagellate widely distributed in tropical to subtropical coastal waters, with some strains exhibiting cytotoxicity, indicating potential ecological and toxicological roles. This study investigated the genetic diversity and adaptability of <em>C. malayensis</em> strains across diverse environmental conditions in Chinese coastal waters. Three distinct genotypes, Genotype 1 (strain DF553), Genotype 2 (DF630), and Genotype 3 comprising strains DF307, DF316, and DF364, were confirmed by the large subunit (LSU) ribosomal DNA phylogenetic analysis, with a protein profiling by the matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry providing supporting evidence for the phenotypic differentiations. The results of growth experiments conducted under varying temperature (15°C to 30°C) and salinity (15 to 35) conditions demonstrated genotype-specific environmental preferences: strain DF553 exhibited an optimal growth at 25°C and 30 salinity, strain DF630 at 30°C and 30, while strains DF307, DF316, and DF364 displayed a wider range of adaptive capacities. These results emphasized the ecological flexibility and adaptive potential of <em>C. malayensis</em>, indicating its ability to thrive in diverse marine environments. The study underscores the importance of genotypic variation in predicting species responses to environmental fluctuations, offering valuable insights for marine ecosystem management and mitigation of harmful algal blooms.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"149 ","pages":"Article 102945"},"PeriodicalIF":4.5,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144865732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Deciphering the photodegradation fate of Brevetoxins: Kinetics, degradation pathways, and toxicity evaluation 解读短叶毒素的光降解命运：动力学、降解途径和毒性评价

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-08-13 DOI: 10.1016/j.hal.2025.102944

Lianbao Chi , Xiaona Zhang , Yongquan Yuan , Huihui Shen , Zhiming Yu , Xiuxian Song

Karenia brevis blooms have emerged as an increasing global concern due to their capacity to produce brevetoxins (BTXs), which are potent marine neurotoxins. The ecological impact of BTXs is significantly modulated by the natural attenuation process, with photodegradation playing a pivotal role. Nevertheless, the fate of BTXs following photodegradation remains inadequately understood. This study elucidates the photodegradation kinetics of three representative BTXs and identifies their transformation products (TPs). The observed first-order photodegradation rate coefficient, based on the logarithmic transformation of dissolved BTXs concentrations against irradiation time, ranged from 0.84 to 2.49 h^-1. Utilizing high-resolution liquid chromatography‒mass spectrometry, three, four, and five TPs were identified for BTX-1, BTX-2, and BTX-3, respectively. All TPs underwent substantial structural modifications with significant mass reductions. Proposed primary photodegradation pathways encompass Ring-opening, alkyl chain cleavage, hydrolysis, dehydroxylation, epoxidation, and β-elimination. Additionally, in silico prediction indicated that the biodegradability of TPs was significantly higher than that of the parent toxins. However, certain TPs exhibited greater toxicities compared to their parent toxins. The coexistence of multiple BTXs and TPs may lead to synergistic toxicity, thereby posing secondary risks to aquatic organisms. Overall, this research will enhance a comprehensive understanding of the environmental behaviors and risks associated with BTXs.

由于短克雷氏菌能够产生短毒素（BTXs），这是一种强效的海洋神经毒素，短克雷氏菌的大量繁殖已成为全球日益关注的问题。BTXs的生态影响受自然衰减过程的显著调节，其中光降解起关键作用。然而，BTXs在光降解后的命运仍然没有得到充分的了解。本研究阐明了三种代表性BTXs的光降解动力学，并鉴定了它们的转化产物（TPs）。基于溶解BTXs浓度随辐照时间的对数变换，观察到的一级光降解率系数范围为0.84 ~ 2.49 h-1。利用高分辨率液相色谱-质谱联用技术，分别鉴定出BTX-1、BTX-2和BTX-3的3种、4种和5种TPs。所有TPs都进行了大量的结构修改，质量显著降低。提出的主要光降解途径包括开环、烷基链裂解、水解、去羟基化、环氧化和β消除。此外，计算机预测表明，TPs的生物降解性显著高于母体毒素。然而，与母体毒素相比，某些TPs表现出更大的毒性。多种BTXs和TPs共存可能导致协同毒性，从而对水生生物构成二次风险。总体而言，本研究将增强对与BTXs相关的环境行为和风险的全面理解。

{"title":"Deciphering the photodegradation fate of Brevetoxins: Kinetics, degradation pathways, and toxicity evaluation","authors":"Lianbao Chi , Xiaona Zhang , Yongquan Yuan , Huihui Shen , Zhiming Yu , Xiuxian Song","doi":"10.1016/j.hal.2025.102944","DOIUrl":"10.1016/j.hal.2025.102944","url":null,"abstract":"<div><div><em>Karenia brevis</em> blooms have emerged as an increasing global concern due to their capacity to produce brevetoxins (BTXs), which are potent marine neurotoxins. The ecological impact of BTXs is significantly modulated by the natural attenuation process, with photodegradation playing a pivotal role. Nevertheless, the fate of BTXs following photodegradation remains inadequately understood. This study elucidates the photodegradation kinetics of three representative BTXs and identifies their transformation products (TPs). The observed first-order photodegradation rate coefficient, based on the logarithmic transformation of dissolved BTXs concentrations against irradiation time, ranged from 0.84 to 2.49 h<sup>-1</sup>. Utilizing high-resolution liquid chromatography‒mass spectrometry, three, four, and five TPs were identified for BTX-1, BTX-2, and BTX-3, respectively. All TPs underwent substantial structural modifications with significant mass reductions. Proposed primary photodegradation pathways encompass Ring-opening, alkyl chain cleavage, hydrolysis, dehydroxylation, epoxidation, and β-elimination. Additionally, <em>in silico</em> prediction indicated that the biodegradability of TPs was significantly higher than that of the parent toxins. However, certain TPs exhibited greater toxicities compared to their parent toxins. The coexistence of multiple BTXs and TPs may lead to synergistic toxicity, thereby posing secondary risks to aquatic organisms. Overall, this research will enhance a comprehensive understanding of the environmental behaviors and risks associated with BTXs.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"149 ","pages":"Article 102944"},"PeriodicalIF":4.5,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Synergistic effects of nutrient competition, biotic interactions, and hydrological regulation drive green tide outbreaks in the South Yellow Sea 营养竞争、生物相互作用和水文调节的协同效应驱动了南黄海绿潮的爆发

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-08-12 DOI: 10.1016/j.hal.2025.102943

Guanbing Feng , Jingfei Liu , Ning Wang , Lihua Xia , Jiahao Fan , Qingqing Mu , Yuqing Sun , Peiming He , Jianheng Zhang

Green tides serve as indicators of coastal ecosystem imbalance, yet their interannual variability and driving mechanisms remain poorly characterized. This study develops the Comprehensive Green Tide Magnitude Index (GTMI) to quantitatively classify South Yellow Sea green tide events (2008–2023) into large- and small-magnitude years. By integrating Seasonal-Trend decomposition (STL) and Random Forest Regression (RFR), we systematically decompose the trend and seasonal components of the time series while preserving its integrity, significantly enhancing the ability to interpret key environmental factors. The results identify silicate, salinity, nitrate, and sea surface temperature as key controlling factors influencing both the magnitude and periodic variability of green tide outbreaks. A partial least squares path model (PLS-PM) reveals a potential mechanism involving nutrient competition, biological interaction, and hydrological regulation. Nutrient overlap between Ulva and phytoplankton triggers resource exclusion, enabling Ulva to dominate through niche preemption and suppress phytoplankton growth, while hydrological forces amplify Ulva expansion and inhibitory effects. The GTMI provides a quantitative assessment tool, and the STL-RF-PLS framework advances mechanistic understanding of multifactorial drivers, offering critical insights for regional green tide mitigation and coastal ecosystem management.

绿潮可作为沿海生态系统失衡的指标，但其年际变化及其驱动机制尚不清楚。本文建立了综合绿潮强度指数（GTMI），将2008-2023年南黄海绿潮事件定量划分为大、小量级年。通过将季节趋势分解（STL）和随机森林回归（RFR）相结合，系统地分解时间序列的趋势和季节成分，同时保持其完整性，显著提高了对关键环境因子的解释能力。结果表明，硅酸盐、盐度、硝酸盐和海面温度是影响绿潮爆发幅度和周期变化的关键控制因素。偏最小二乘路径模型（PLS-PM）揭示了涉及养分竞争、生物相互作用和水文调节的潜在机制。Ulva与浮游植物之间的养分重叠引发资源排斥，使Ulva通过生态位抢占占据主导地位，抑制浮游植物生长，而水文力量放大了Ulva的扩张和抑制作用。GTMI提供了一个定量评估工具，STL-RF-PLS框架推进了对多因素驱动因素的机制理解，为区域绿潮缓解和沿海生态系统管理提供了重要见解。

{"title":"Synergistic effects of nutrient competition, biotic interactions, and hydrological regulation drive green tide outbreaks in the South Yellow Sea","authors":"Guanbing Feng , Jingfei Liu , Ning Wang , Lihua Xia , Jiahao Fan , Qingqing Mu , Yuqing Sun , Peiming He , Jianheng Zhang","doi":"10.1016/j.hal.2025.102943","DOIUrl":"10.1016/j.hal.2025.102943","url":null,"abstract":"<div><div>Green tides serve as indicators of coastal ecosystem imbalance, yet their interannual variability and driving mechanisms remain poorly characterized. This study develops the Comprehensive Green Tide Magnitude Index (GTMI) to quantitatively classify South Yellow Sea green tide events (2008–2023) into large- and small-magnitude years. By integrating Seasonal-Trend decomposition (STL) and Random Forest Regression (RFR), we systematically decompose the trend and seasonal components of the time series while preserving its integrity, significantly enhancing the ability to interpret key environmental factors. The results identify silicate, salinity, nitrate, and sea surface temperature as key controlling factors influencing both the magnitude and periodic variability of green tide outbreaks. A partial least squares path model (PLS-PM) reveals a potential mechanism involving nutrient competition, biological interaction, and hydrological regulation. Nutrient overlap between <em>Ulva</em> and phytoplankton triggers resource exclusion, enabling <em>Ulva</em> to dominate through niche preemption and suppress phytoplankton growth, while hydrological forces amplify <em>Ulva</em> expansion and inhibitory effects. The GTMI provides a quantitative assessment tool, and the STL-RF-PLS framework advances mechanistic understanding of multifactorial drivers, offering critical insights for regional green tide mitigation and coastal ecosystem management.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"149 ","pages":"Article 102943"},"PeriodicalIF":4.5,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144852956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Protected high-mountain rivers harbor widespread toxic Microcoleus-dominated mats with distinct genetic profiles 受保护的高山河流拥有广泛分布的有毒微藻，它们以独特的遗传特征为主

IF 4.5 1区生物学 Q1 MARINE & FRESHWATER BIOLOGY

Harmful Algae

Pub Date : 2025-08-11 DOI: 10.1016/j.hal.2025.102942

Albano Diez-Chiappe, María Ángeles Muñoz-Martín, Samuel Cirés, Antonio Quesada, Elvira Perona

Toxic Microcoleus remains poorly studied in mountain freshwaters, where cyanotoxins threaten public and ecological health, particularly in protected areas that hold high ecological value and attract a high density of visitors. This study investigated the proliferation of cyanobacterial mats and cyanotoxin production in two high-mountain rivers flowing through a National Park. Our results confirmed the widespread and recurrent proliferation of Microcoleus-dominated mats containing the neurotoxins anatoxin-a and homoanatoxin-a. Mat coverage showed potentially hazardous levels, reaching up to 40-50 % of the riverbed. Comprehensive genetic characterization through metabarcoding sequencing (targeting 16S rRNA and cyanotoxin-biosynthesis genes) revealed a significant differential distribution of Microcoleus genotypes between two adjacent high-mountain rivers, as well as the persistence of the anaF gene from Microcoleus. Although saxitoxins and microcystins were not detected, the sxtA gene closely related to Scytonema and mcyE from Nostoc-like species were occasionally found. This is the first report of abundant proliferations of anatoxin-producing Microcoleus in Spain, broadening research into Southern and Mediterranean Europe, where toxic Microcoleus remains underreported. These results reinforce the importance of genetic analyses as valuable tools for understanding Microcoleus population dynamics. Our findings highlight that toxic mats should be considered a potential threat in minimally impacted mountain freshwaters, especially those frequently visited for their high ecological value.

有毒小囊藻在山区淡水中的研究仍然很少，那里的蓝藻毒素威胁着公众和生态健康，特别是在具有高生态价值和吸引高密度游客的保护区。本研究调查了流经国家公园的两条高山河流中蓝藻席的增殖和蓝藻毒素的产生。我们的研究结果证实了含有anatoxin-a和homanatoxin -a神经毒素的microcolus主导的垫子的广泛和复发性增殖。河席覆盖面积达到河床的40- 50%，显示出潜在的危险水平。通过元条形码测序（针对16S rRNA和蓝藻毒素-生物合成基因）的综合遗传特征揭示了相邻的两条高山河流之间微藻基因型分布的显著差异，以及微藻anaF基因的持久性。虽然没有检测到蛤蚌毒素和微囊藻毒素，但偶尔在nostoc样物种中发现与Scytonema和mcyE密切相关的sxtA基因。这是西班牙首次报道产生anatoxin的Microcoleus大量增殖，扩大了对南欧和地中海欧洲的研究，在那里有毒的Microcoleus仍然被低估。这些结果加强了遗传分析作为了解小豆种群动态的有价值工具的重要性。我们的研究结果强调，在受影响最小的山区淡水中，特别是那些因其高生态价值而经常访问的山区淡水中，应将有毒席子视为潜在威胁。

{"title":"Protected high-mountain rivers harbor widespread toxic Microcoleus-dominated mats with distinct genetic profiles","authors":"Albano Diez-Chiappe, María Ángeles Muñoz-Martín, Samuel Cirés, Antonio Quesada, Elvira Perona","doi":"10.1016/j.hal.2025.102942","DOIUrl":"10.1016/j.hal.2025.102942","url":null,"abstract":"<div><div>Toxic <em>Microcoleus</em> remains poorly studied in mountain freshwaters, where cyanotoxins threaten public and ecological health, particularly in protected areas that hold high ecological value and attract a high density of visitors. This study investigated the proliferation of cyanobacterial mats and cyanotoxin production in two high-mountain rivers flowing through a National Park. Our results confirmed the widespread and recurrent proliferation of <em>Microcoleus</em>-dominated mats containing the neurotoxins anatoxin-a and homoanatoxin-a. Mat coverage showed potentially hazardous levels, reaching up to 40-50 % of the riverbed. Comprehensive genetic characterization through metabarcoding sequencing (targeting 16S rRNA and cyanotoxin-biosynthesis genes) revealed a significant differential distribution of <em>Microcoleus</em> genotypes between two adjacent high-mountain rivers, as well as the persistence of the <em>anaF</em> gene from <em>Microcoleus.</em> Although saxitoxins and microcystins were not detected, the <em>sxtA</em> gene closely related to <em>Scytonema</em> and <em>mcyE</em> from <em>Nostoc</em>-like species were occasionally found. This is the first report of abundant proliferations of anatoxin-producing <em>Microcoleus</em> in Spain, broadening research into Southern and Mediterranean Europe, where toxic <em>Microcoleus</em> remains underreported. These results reinforce the importance of genetic analyses as valuable tools for understanding <em>Microcoleus</em> population dynamics. Our findings highlight that toxic mats should be considered a potential threat in minimally impacted mountain freshwaters, especially those frequently visited for their high ecological value.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"149 ","pages":"Article 102942"},"PeriodicalIF":4.5,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0