This study presents the first integrative assessment of Egeria densa Planch. invasion in Northern Eurasia using molecular phylogenetics and ensemble species distribution modeling based on over 3200 occurrence records. Genetic analyses revealed high similarity among distant populations, indicating few invasion sources and predominance of clonal reproduction. Modeling identified annual mean temperature, mean temperature of the coldest quarter, and annual precipitation as principal climatic determinants. Results improve predictions of range expansion under climate warming and support targeted management of this invasive species.
{"title":"Egeria densa Planch. (Hydrocharitaceae) in Northern Eurasia: genetic similarity and range expansion","authors":"Andrey Efremov , Elena Antonova , Vasily Vishnyakov , Veronika Grishina , Yuriy Davidyuk , Anastasia Kuznetsova , Aidar Zimnurov","doi":"10.1016/j.aquabot.2025.103970","DOIUrl":"10.1016/j.aquabot.2025.103970","url":null,"abstract":"<div><div>This study presents the first integrative assessment of <em>Egeria densa</em> Planch. invasion in Northern Eurasia using molecular phylogenetics and ensemble species distribution modeling based on over 3200 occurrence records. Genetic analyses revealed high similarity among distant populations, indicating few invasion sources and predominance of clonal reproduction. Modeling identified annual mean temperature, mean temperature of the coldest quarter, and annual precipitation as principal climatic determinants. Results improve predictions of range expansion under climate warming and support targeted management of this invasive species.</div></div>","PeriodicalId":8273,"journal":{"name":"Aquatic Botany","volume":"203 ","pages":"Article 103970"},"PeriodicalIF":2.6,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sargassum muticum is one of the dominant species in the coastal algal communities of China, and investigating its response to high-temperature stress is crucial for algal resource conservation and utilization. This study assessed the effects of exogenous salicylic acid (SA: 10.0 μg·mL−1) on the heat tolerance of S. muticum under high light (160 μmol photons·m−2·s−1) and low light (80 μmol photons·m−2·s−1) at 15°C and 30°C, respectively. The results indicate that at 15°C, growth rate, activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), and the expression of the hsp70 gene in S. muticum were significantly higher under high light than under low light conditions, with non-significant effect of SA. At the elevated temperature of 30°C, S. muticum was able to maintain a daily growth rate exceeding 9 % within 3 days, and the maximum photochemical efficiency (Fv/Fm) showed no significant changes. However, under low light conditions, the content of photosynthetic pigments and the actual quantum yield of PS II (Y(II)) decreased significantly, while malondialdehyde (MDA) content increased markedly; conversely, little change was observed in the high light group. Additionally, the addition of SA significantly enhanced the growth of S. muticum in both high and low light conditions, regulated photosynthetic characteristics, increased the expression of the rbcL gene, enhanced peroxidase activity, and further promoted the expression of the hsp70 gene induced by high temperature. These findings provide insights for the artificial cultivation of S. muticum under challenging environmental conditions.
马尾藻是中国沿海藻类群落的优势种之一，研究其对高温胁迫的响应对藻类资源的保护和利用具有重要意义。本研究评估了外源水杨酸（SA: 10.0 μg·mL−1）对15°C和30°C强光（160 μmol光子·m−2·s−1）和弱光（80 μmol光子·m−2·s−1）下白葡萄耐热性的影响。结果表明，在15℃条件下，强光条件下，白葡萄的生长速度、抗氧化酶超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）的活性以及hsp70基因的表达量显著高于弱光条件下，SA的影响不显著。在30℃的高温条件下，3 d内muticum的日生长速度可保持在9 %以上，最大光化学效率（Fv/Fm）无显著变化。但在弱光条件下，光合色素含量和PS II （Y(II)）的实际量子产率显著降低，丙二醛（MDA）含量显著升高；相反，高光组几乎没有变化。此外，SA的添加显著促进了muticum在高、弱光条件下的生长，调节了光合特性，增加了rbcL基因的表达，增强了过氧化物酶活性，并进一步促进了高温诱导的hsp70基因的表达。这些发现为在恶劣的环境条件下人工培养muticum提供了新的思路。
{"title":"Effect of exogenous salicylic acid on high temperature resistance of Sargassum muticum under different light conditions","authors":"Fang Lü, Xiaohui Liu, Liuqing Tang, Meili Xin, Wendan Chi, Dongmei Zhan, Haiyi Wu","doi":"10.1016/j.aquabot.2025.103967","DOIUrl":"10.1016/j.aquabot.2025.103967","url":null,"abstract":"<div><div><em>Sargassum muticum</em> is one of the dominant species in the coastal algal communities of China, and investigating its response to high-temperature stress is crucial for algal resource conservation and utilization. This study assessed the effects of exogenous salicylic acid (SA: 10.0 μg·mL<sup>−1</sup>) on the heat tolerance of <em>S. muticum</em> under high light (160 μmol photons·m<sup>−2</sup>·s<sup>−1</sup>) and low light (80 μmol photons·m<sup>−2</sup>·s<sup>−1</sup>) at 15°C and 30°C, respectively. The results indicate that at 15°C, growth rate, activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), and the expression of the <em>hsp</em>70 gene in <em>S. muticum</em> were significantly higher under high light than under low light conditions, with non-significant effect of SA. At the elevated temperature of 30°C, <em>S. muticum</em> was able to maintain a daily growth rate exceeding 9 % within 3 days, and the maximum photochemical efficiency (<em>F</em>v/<em>F</em>m) showed no significant changes. However, under low light conditions, the content of photosynthetic pigments and the actual quantum yield of PS II (Y(II)) decreased significantly, while malondialdehyde (MDA) content increased markedly; conversely, little change was observed in the high light group. Additionally, the addition of SA significantly enhanced the growth of <em>S. muticum</em> in both high and low light conditions, regulated photosynthetic characteristics, increased the expression of the <em>rbc</em>L gene, enhanced peroxidase activity, and further promoted the expression of the <em>hsp</em>70 gene induced by high temperature. These findings provide insights for the artificial cultivation of <em>S. muticum</em> under challenging environmental conditions.</div></div>","PeriodicalId":8273,"journal":{"name":"Aquatic Botany","volume":"203 ","pages":"Article 103967"},"PeriodicalIF":2.6,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The beaching events of holopelagic (free-floating) Sargassum, marked by the substantial influx of brown seaweed along the Atlantic coastlines, present a considerable challenge to marine ecosystems and coastal economies, as its clonal growth disrupts local biodiversity and affects industries including tourism and fisheries. The Sargassum fluitans and S. natans have been found for the first time along the Atlantic coast of Morocco, North Africa, between late March and early May 2024. The beached biomass consisted of the main morphotypes identified in the tropical Atlantic Ocean: S. fluitans var. fluitans (syn. S. fluitans III) and S. natans var. natans (syn. S. natans I) and S. natans var. wingei (syn. S. natans VIII). The in-situ observation of drifting Sargassum populations revealed a density of 10 ± 3 fronds/m² where S. natans var. wingei was the dominant form (58 %). Leading us think of the origin of their transport and stranding on the Atlantic Moroccan coasts that might have been caused by extreme climatic and hydrodynamic events that occurred after Nelson storm late March 2024. Major environmental drivers, including the Sea surface temperature (SST) variability, North Atlantic Oscillation (NAO) index and prevailing wind patterns were considered. This unusual event should prompt more monitoring and vigilance regarding the circulation of marine currents and species introduced into this region.
以褐藻大量涌入大西洋海岸线为标志的全浮游（自由漂浮）马尾藻搁浅事件，对海洋生态系统和沿海经济构成了相当大的挑战，因为其无性系生长破坏了当地的生物多样性，并影响到旅游业和渔业等行业。2024年3月底至5月初，在北非摩洛哥的大西洋沿岸首次发现了马尾藻和S. natans。滩头生物量主要由热带大西洋中发现的主要形态类型组成：S. fluitans var. fluitans （syn. S. fluitans III）、S. natans var. natans （syn. S. natans I）和S. natans var. wingei （syn. S. natans VIII）。现场观测马尾藻种群密度为10 ± 3株/m²，其中翼尾藻为优势种（58 %）。这让我们想到了它们在大西洋摩洛哥海岸的运输和搁浅的起源，这可能是由2024年3月下旬纳尔逊风暴后发生的极端气候和水动力事件造成的。主要的环境驱动因素包括海温（SST）变率、北大西洋涛动（NAO）指数和盛行风型。这一不寻常的事件应促使人们对进入该地区的洋流和物种的环流进行更多的监测和警惕。
{"title":"Trans-Atlantic drift of the holopelagic Sargassum natans and S. fluitans on the Moroccan Atlantic coast: First report linked to unusual climatic event and ocean currents in the northeastern Atlantic Ocean","authors":"Khansae Kamal , Khaoula Khaya , Zahira Belattmania , Abdellatif Chaouti , Joao Neiva , Aschwin Hillebrand Engelen , Valérie Stiger-Pouvreau , Ester A. Serrão , Brahim Sabour","doi":"10.1016/j.aquabot.2025.103966","DOIUrl":"10.1016/j.aquabot.2025.103966","url":null,"abstract":"<div><div>The beaching events of holopelagic (free-floating) <em>Sargassum</em>, marked by the substantial influx of brown seaweed along the Atlantic coastlines, present a considerable challenge to marine ecosystems and coastal economies, as its clonal growth disrupts local biodiversity and affects industries including tourism and fisheries. The <em>Sargassum fluitans</em> and <em>S. natans</em> have been found for the first time along the Atlantic coast of Morocco, North Africa, between late March and early May 2024. The beached biomass consisted of the main morphotypes identified in the tropical Atlantic Ocean: <em>S. fluitans</em> var. <em>fluitans</em> (syn. <em>S. fluitans</em> III) and <em>S. natans</em> var. <em>natans</em> (syn. <em>S. natans</em> I) and <em>S. natans</em> var. <em>wingei</em> (syn. <em>S. natans</em> VIII). The <em>in-situ</em> observation of drifting <em>Sargassum</em> populations revealed a density of 10 ± 3 fronds/m² where <em>S. natans</em> var. <em>wingei</em> was the dominant form (58 %). Leading us think of the origin of their transport and stranding on the Atlantic Moroccan coasts that might have been caused by extreme climatic and hydrodynamic events that occurred after Nelson storm late March 2024. Major environmental drivers, including the Sea surface temperature (SST) variability, North Atlantic Oscillation (NAO) index and prevailing wind patterns were considered. This unusual event should prompt more monitoring and vigilance regarding the circulation of marine currents and species introduced into this region.</div></div>","PeriodicalId":8273,"journal":{"name":"Aquatic Botany","volume":"203 ","pages":"Article 103966"},"PeriodicalIF":2.6,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-14DOI: 10.1016/j.aquabot.2025.103968
Belén Roger-Baynat, Marta Sansón, Daniel Álvarez-Canali, Carlos Sangil
In recent decades, many species of tropical distribution have arrived in the Canary Islands due to tropicalization and direct and indirect anthropogenic activity. This is the case of the Caribbean seaweed Halimeda incrassata (Bryopsidales, Chlorophyta) that began to be detected in the eastern Atlantic in 2005 and is now found in the Canary Islands, Madeira, Azores, and the Mediterranean. In this study, an ex-situ experimental approach was carried out to assess the thermal and light tolerance of the species to understand its preferences and predict its expansion. Three experiments were performed, testing temperature and light individually and their interaction. The variables measured were thallus growth (percentage of surface area and increase of number of segments) and net photosynthesis. Results indicate that temperature is the most limiting factor to its growth, with higher temperatures being the most favorable (26–28ºC), while light intensity has a more negligible effect on the species. Consequently, H. incrassata could expand latitudinally until 40ºN, where temperature is over 20ºC for at least several months over the year. As an ecosystem engineer it can modify the environment and the communities where it is established, it is expected to compete with native species such as seagrasses, other macroalgae and garden eel. Further experiments, including acidification conditions and in-situ monitoring, should also be considered to complete the information on its growth limits.
{"title":"Assessing the response of Halimeda incrassata to temperature and light to predict its spread in the NE Atlantic","authors":"Belén Roger-Baynat, Marta Sansón, Daniel Álvarez-Canali, Carlos Sangil","doi":"10.1016/j.aquabot.2025.103968","DOIUrl":"10.1016/j.aquabot.2025.103968","url":null,"abstract":"<div><div>In recent decades, many species of tropical distribution have arrived in the Canary Islands due to tropicalization and direct and indirect anthropogenic activity. This is the case of the Caribbean seaweed <em>Halimeda incrassata</em> (Bryopsidales, Chlorophyta) that began to be detected in the eastern Atlantic in 2005 and is now found in the Canary Islands, Madeira, Azores, and the Mediterranean. In this study, an <em>ex-situ</em> experimental approach was carried out to assess the thermal and light tolerance of the species to understand its preferences and predict its expansion. Three experiments were performed, testing temperature and light individually and their interaction. The variables measured were thallus growth (percentage of surface area and increase of number of segments) and net photosynthesis. Results indicate that temperature is the most limiting factor to its growth, with higher temperatures being the most favorable (26–28ºC), while light intensity has a more negligible effect on the species. Consequently, <em>H. incrassata</em> could expand latitudinally until 40ºN, where temperature is over 20ºC for at least several months over the year. As an ecosystem engineer it can modify the environment and the communities where it is established, it is expected to compete with native species such as seagrasses, other macroalgae and garden eel. Further experiments, including acidification conditions and <em>in-situ</em> monitoring, should also be considered to complete the information on its growth limits.</div></div>","PeriodicalId":8273,"journal":{"name":"Aquatic Botany","volume":"203 ","pages":"Article 103968"},"PeriodicalIF":2.6,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Leaf mass per area (LMA) is closely linked to plant resource investment strategies. In most terrestrial plants, variation in LMA is primarily driven by leaf density. However, mangroves develop succulent leaves with high water content as an adaptation to saline environments. We therefore hypothesized that in mangroves, leaf thickness cannot be overlooked in explaining LMA variation, and that it exhibits greater phylogenetic plasticity than density. To test this, we analyzed the relative contributions of thickness and density to LMA variation and assessed their phylogenetic signals across 30 mangrove species in China. The results show that thickness and density contribute comparably to LMA variation in mangrove species. The covariation between LMA and leaf thickness is largely phylogenetically independent, whereas the relationship between LMA and leaf density is phylogenetically conserved. This decoupling indicates that mangroves regulate LMA through environmentally responsive adjustments in thickness, while leaf density is a more evolutionarily constrained trait. Consequently, these findings call into question the broad applicability of LMA as a direct indicator of plant resource investment strategies in mangroves.
{"title":"Incorporating evolutionary history in the explanation of the variation in leaf mass per area and its components of mangrove species","authors":"Justin Rugema , Waseem Akram , Jing Gao , Zachee Gasana , Frida Sidik , Lili Wei","doi":"10.1016/j.aquabot.2025.103969","DOIUrl":"10.1016/j.aquabot.2025.103969","url":null,"abstract":"<div><div>Leaf mass per area (LMA) is closely linked to plant resource investment strategies. In most terrestrial plants, variation in LMA is primarily driven by leaf density. However, mangroves develop succulent leaves with high water content as an adaptation to saline environments. We therefore hypothesized that in mangroves, leaf thickness cannot be overlooked in explaining LMA variation, and that it exhibits greater phylogenetic plasticity than density. To test this, we analyzed the relative contributions of thickness and density to LMA variation and assessed their phylogenetic signals across 30 mangrove species in China. The results show that thickness and density contribute comparably to LMA variation in mangrove species. The covariation between LMA and leaf thickness is largely phylogenetically independent, whereas the relationship between LMA and leaf density is phylogenetically conserved. This decoupling indicates that mangroves regulate LMA through environmentally responsive adjustments in thickness, while leaf density is a more evolutionarily constrained trait. Consequently, these findings call into question the broad applicability of LMA as a direct indicator of plant resource investment strategies in mangroves.</div></div>","PeriodicalId":8273,"journal":{"name":"Aquatic Botany","volume":"203 ","pages":"Article 103969"},"PeriodicalIF":2.6,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-13DOI: 10.1016/j.aquabot.2025.103965
Abeli Thomas, Bacchetta Alice, Basilico Flavio, Berardo Pietro, Colli Alice, Colonna Ginevra, Pastor Bini Alessandra Balbina, Ruzzoli Alessia, Tucci Martina, Vesconi Giovanna Angela, Vitaloni Diana, Tarascio Martina
Isoëtes malinverniana is a critically endangered quillwort endemic to north-western Italy. Although some aspects of its reproductive biology are well known, megaspore and sporophyte germination ecology have never been studied in detail. In this study, we investigate and clarify the thermal requirements for megaspore germination and sporophyte emergence in I. malinverniana. We tested the effect of five constant temperatures (10, 15, 20, 25, 30 °C) and one alternating temperature (25/15 °C) on megaspore germination and sporophyte emergence in I. malinverniana. Moreover, we tested the effect of light and dark on megaspore germination and, the species self-compatibility and apomictic reproduction. Our results suggest that the optimal temperatures for megaspore germination and sporophyte emergence were 20 °C and 25/15 °C, reaching approximately 80 % germination at these temperatures after eight weeks. Spore germination did not occur at 10 °C and decreased at temperatures above 25 °C. Germination and emergence speed were also positively related to temperature. Megaspore and sporophyte of I. malinverniana germinated and emerged in the dark, but at a lower percentage than in full light. Our study suggests that I. malinverniana is self-compatible and cannot reproduce apomictically.
{"title":"Megaspore germination and sporophyte emergence requirements in the critically endangered endemic quillwort Isoëtes malinverniana","authors":"Abeli Thomas, Bacchetta Alice, Basilico Flavio, Berardo Pietro, Colli Alice, Colonna Ginevra, Pastor Bini Alessandra Balbina, Ruzzoli Alessia, Tucci Martina, Vesconi Giovanna Angela, Vitaloni Diana, Tarascio Martina","doi":"10.1016/j.aquabot.2025.103965","DOIUrl":"10.1016/j.aquabot.2025.103965","url":null,"abstract":"<div><div><em>Isoëtes malinverniana</em> is a critically endangered quillwort endemic to north-western Italy. Although some aspects of its reproductive biology are well known, megaspore and sporophyte germination ecology have never been studied in detail. In this study, we investigate and clarify the thermal requirements for megaspore germination and sporophyte emergence in <em>I. malinverniana</em>. We tested the effect of five constant temperatures (10, 15, 20, 25, 30 °C) and one alternating temperature (25/15 °C) on megaspore germination and sporophyte emergence in <em>I. malinverniana</em>. Moreover, we tested the effect of light and dark on megaspore germination and, the species self-compatibility and apomictic reproduction. Our results suggest that the optimal temperatures for megaspore germination and sporophyte emergence were 20 °C and 25/15 °C, reaching approximately 80 % germination at these temperatures after eight weeks. Spore germination did not occur at 10 °C and decreased at temperatures above 25 °C. Germination and emergence speed were also positively related to temperature. Megaspore and sporophyte of <em>I. malinverniana</em> germinated and emerged in the dark, but at a lower percentage than in full light. Our study suggests that <em>I. malinverniana</em> is self-compatible and cannot reproduce apomictically.</div></div>","PeriodicalId":8273,"journal":{"name":"Aquatic Botany","volume":"203 ","pages":"Article 103965"},"PeriodicalIF":2.6,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.aquabot.2025.103964
Zhixin Zhong , Liuyuan Zou , Jie Wang , Xiaochen Cheng , Gaoquan He , Le-Zheng Qin
Halophila beccarii, a key habitat-forming seagrass in estuarine and coastal ecosystems, faces increasing threats from rising seawater temperatures. However, its survival strategies and physiological responses to thermal stress remain poorly characterized. This study conducted a field observation investigating the population dynamics of H. beccarii in the Nandu River estuary, China, over two years and a temperature experiment examining its growth, morphological traits, and non-structural carbohydrate (NSC) dynamics under manipulated thermal stress (exposure to 25°C, 30°C, and 35°C for 28 days followed by a 30-day recovery period at 25°C). The results of the field observation showed that extreme temperatures (>40°C) in May 2023 triggered sharp declines in shoot density, biomass, and NSC content, resulting in a near-complete meadow-scale die-off by June 2023. In particular, the enhanced belowground starch reserves coincided with a higher shoot density and biomass, suggesting that meadows with greater biomass and NSC reserves were likely more resilient to thermal stress. Seedling recruitment during October 2023 partially facilitated population recovery. Elevated experimental temperatures (30°C and 35°C) reduced shoot density and inhibited clonal propagation. Leaf width and aboveground soluble sugar content increased at 30°C, suggesting morphological adaptation. During recovery, plant height, rhizome internode length, and belowground NSC content increased, indicating enhanced energy storage and recovery potential. These findings emphasize the lasting effects of thermal stress on H. beccarii, indicating its low resilience to extreme heat stress under future climate change scenarios.
{"title":"Effects of increasing temperature on the growth, survival, and non-structural carbohydrate content of the seagrass Halophila beccarii","authors":"Zhixin Zhong , Liuyuan Zou , Jie Wang , Xiaochen Cheng , Gaoquan He , Le-Zheng Qin","doi":"10.1016/j.aquabot.2025.103964","DOIUrl":"10.1016/j.aquabot.2025.103964","url":null,"abstract":"<div><div><em>Halophila beccarii</em>, a key habitat-forming seagrass in estuarine and coastal ecosystems, faces increasing threats from rising seawater temperatures. However, its survival strategies and physiological responses to thermal stress remain poorly characterized. This study conducted a field observation investigating the population dynamics of <em>H. beccarii</em> in the Nandu River estuary, China, over two years and a temperature experiment examining its growth, morphological traits, and non-structural carbohydrate (NSC) dynamics under manipulated thermal stress (exposure to 25°C, 30°C, and 35°C for 28 days followed by a 30-day recovery period at 25°C). The results of the field observation showed that extreme temperatures (>40°C) in May 2023 triggered sharp declines in shoot density, biomass, and NSC content, resulting in a near-complete meadow-scale die-off by June 2023. In particular, the enhanced belowground starch reserves coincided with a higher shoot density and biomass, suggesting that meadows with greater biomass and NSC reserves were likely more resilient to thermal stress. Seedling recruitment during October 2023 partially facilitated population recovery. Elevated experimental temperatures (30°C and 35°C) reduced shoot density and inhibited clonal propagation. Leaf width and aboveground soluble sugar content increased at 30°C, suggesting morphological adaptation. During recovery, plant height, rhizome internode length, and belowground NSC content increased, indicating enhanced energy storage and recovery potential. These findings emphasize the lasting effects of thermal stress on <em>H. beccarii</em>, indicating its low resilience to extreme heat stress under future climate change scenarios.</div></div>","PeriodicalId":8273,"journal":{"name":"Aquatic Botany","volume":"203 ","pages":"Article 103964"},"PeriodicalIF":2.6,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145475335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The conservation of aquatic plants in freshwater ecosystems is essential for supporting aquatic animal communities. However, conducting field surveys of aquatic plants in riverine environments remains challenging, posing as a barrier to understanding their habitats. In this study, vegetation surveys and environmental DNA (eDNA) metabarcoding were conducted in the main channel, connected ponds, and isolated ponds of the Tokachi River—one of the major rivers in Japan. The aim of this study was to (i) compare species detection between eDNA metabarcoding and field survey results using multiple markers, (ii) determine whether eDNA detection of aquatic plants varies across water body types, and (iii) identify whether detection differences are associated with taxonomic groups or life forms of aquatic plants. A total of 34 species were recorded through field surveys, and 29 species were detected through eDNA analysis. At the species level, 24 species (approximately 80 %) could only be detected using one marker. Isolated ponds yielded the highest number of species in field and eDNA surveys. The families Potamogetonaceae and Poaceae were most frequently detected by eDNA (five species each); notably, both families were also well represented in vegetation surveys across many sites. Overall, submerged plants were detected more frequently by eDNA than emergent plants across all water body type. Additionally, eDNA was able to detect rare species. These findings suggest that eDNA surveys are a valuable tool for detecting submerged and rare aquatic plant species in large river systems, particularly where field-based identification is limited.
{"title":"Variations in environmental DNA deteAQBOT 103954ction of aquatic plants across water body types: A case study of the Tokachi River","authors":"Chigaya Enju , Souta Nakajima , Kenji Tsuri , Ryusuke Shinohara , Kazuki Kanno , Keiko Muraoka , Koji Katagiri","doi":"10.1016/j.aquabot.2025.103954","DOIUrl":"10.1016/j.aquabot.2025.103954","url":null,"abstract":"<div><div>The conservation of aquatic plants in freshwater ecosystems is essential for supporting aquatic animal communities. However, conducting field surveys of aquatic plants in riverine environments remains challenging, posing as a barrier to understanding their habitats. In this study, vegetation surveys and environmental DNA (eDNA) metabarcoding were conducted in the main channel, connected ponds, and isolated ponds of the Tokachi River—one of the major rivers in Japan. The aim of this study was to (i) compare species detection between eDNA metabarcoding and field survey results using multiple markers, (ii) determine whether eDNA detection of aquatic plants varies across water body types, and (iii) identify whether detection differences are associated with taxonomic groups or life forms of aquatic plants. A total of 34 species were recorded through field surveys, and 29 species were detected through eDNA analysis. At the species level, 24 species (approximately 80 %) could only be detected using one marker. Isolated ponds yielded the highest number of species in field and eDNA surveys. The families Potamogetonaceae and Poaceae were most frequently detected by eDNA (five species each); notably, both families were also well represented in vegetation surveys across many sites. Overall, submerged plants were detected more frequently by eDNA than emergent plants across all water body type. Additionally, eDNA was able to detect rare species. These findings suggest that eDNA surveys are a valuable tool for detecting submerged and rare aquatic plant species in large river systems, particularly where field-based identification is limited.</div></div>","PeriodicalId":8273,"journal":{"name":"Aquatic Botany","volume":"203 ","pages":"Article 103954"},"PeriodicalIF":2.6,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145369775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-15DOI: 10.1016/j.aquabot.2025.103953
Alyssa J. Anderson, Ryan M. Wersal, Christopher T. Ruhland
Parrotfeather (Myriophyllum aquaticum (Vell.) Verdc.) is a heterophyllous, perennial aquatic invasive plant. Since parrotfeather’s arrival in the U.S. in the late 1800s, there is yet to be wide-spread establishment in the Midwestern United States (Midwest). The current study utilized pulse amplitude modulated chlorophyll fluorescence and gas exchange analyses to determine if there is a physiological mechanism that limits parrotfeather colonization in the Midwest. Fluorescence parameters were taken at water temperatures between 0 and 45°C, and gas exchange measurements were examined at 4, 25 and 35°C. The photosynthetic ecophysiology of parrotfeather was compared to Eurasian watermilfoil (Myriophyllum spicatum L.) and a hybrid strain of watermilfoil (Myriophyllum spicatum x Myriophyllum sibiricum) as the latter two plants are widespread throughout the Midwest. The ratio of variable to maximal fluorescence (Fv/Fm) in emergent and submerged parrotfeather averaged 0.80 and 0.65, respectively, at temperatures between 0 and 35°C and declined at > 40°C. In addition, light-adapted quantum yield of photosystem II (ϕPSII) was lowest at temperatures between 0 and 10°C and 40–45°C in submersed leaves. Net photosynthetic rates were highest at 25°C for emergent and submerged parrotfeather and averaged 8.83 μmol m−2 s−1 and 0.00107 μmol g−1 s−1 FW, respectively. Carbon assimilation rates in submersed parrotfeather were significantly lower than those observed in the Eurasian and hybrid milfoils. Lastly, the light compensation points were consistently lower in submersed parrotfeather than the other milfoils with values ≤ 55 μmol m−2 s−1 at 4°C and 25°C. Based on current photosynthetic ecophysiology data, these species of Myriophyllum maintain positive photosynthetic rates at temperatures near 4°C.
{"title":"Comparative analysis of the photosynthetic ecophysiology of Myriophyllum aquaticum and congeneric milfoils and invasion potential into the Midwestern United States","authors":"Alyssa J. Anderson, Ryan M. Wersal, Christopher T. Ruhland","doi":"10.1016/j.aquabot.2025.103953","DOIUrl":"10.1016/j.aquabot.2025.103953","url":null,"abstract":"<div><div>Parrotfeather (<em>Myriophyllum aquaticum</em> (Vell.) Verdc.) is a heterophyllous, perennial aquatic invasive plant. Since parrotfeather’s arrival in the U.S. in the late 1800s, there is yet to be wide-spread establishment in the Midwestern United States (Midwest). The current study utilized pulse amplitude modulated chlorophyll fluorescence and gas exchange analyses to determine if there is a physiological mechanism that limits parrotfeather colonization in the Midwest. Fluorescence parameters were taken at water temperatures between 0 and 45°C, and gas exchange measurements were examined at 4, 25 and 35°C. The photosynthetic ecophysiology of parrotfeather was compared to Eurasian watermilfoil (<em>Myriophyllum spicatum</em> L.) and a hybrid strain of watermilfoil (<em>Myriophyllum spicatum</em> x <em>Myriophyllum sibiricum</em>) as the latter two plants are widespread throughout the Midwest. The ratio of variable to maximal fluorescence (F<sub>v</sub>/F<sub>m</sub>) in emergent and submerged parrotfeather averaged 0.80 and 0.65, respectively, at temperatures between 0 and 35°C and declined at > 40°C. In addition, light-adapted quantum yield of photosystem II (ϕ<sub>PSII</sub>) was lowest at temperatures between 0 and 10°C and 40–45°C in submersed leaves. Net photosynthetic rates were highest at 25°C for emergent and submerged parrotfeather and averaged 8.83 μmol m<sup>−2</sup> s<sup>−1</sup> and 0.00107 μmol g<sup>−</sup><sup>1</sup> s<sup>−1</sup> FW, respectively. Carbon assimilation rates in submersed parrotfeather were significantly lower than those observed in the Eurasian and hybrid milfoils. Lastly, the light compensation points were consistently lower in submersed parrotfeather than the other milfoils with values ≤ 55 μmol m<sup>−2</sup> s<sup>−1</sup> at 4°C and 25°C. Based on current photosynthetic ecophysiology data, these species of <em>Myriophyllum</em> maintain positive photosynthetic rates at temperatures near 4°C.</div></div>","PeriodicalId":8273,"journal":{"name":"Aquatic Botany","volume":"202 ","pages":"Article 103953"},"PeriodicalIF":2.6,"publicationDate":"2025-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145358517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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