Rujia He, Dayong Zhao, Qi Zhou, Qinglong L. Wu, Jin Zeng
Understanding the response of microbial communities to different ecological regimes in eutrophic lakes and the underlying assembly mechanisms is of great significance for revealing the biodiversity maintenance mechanisms of lake ecosystems under alternative stable states. However, our current understanding of the response of sediment microbial communities under emergent macrophytes to regime shifts remains limited. Here, we demonstrated, for the first time, the asynchronous variations of littoral sediment bacterial and fungal communities, regarding the microbial diversities, assembly mechanisms, and inter‐kingdom interactions across three lake regional regimes: macrophyte‐dominated, transitional, and phytoplankton‐dominated. We found the alpha diversities of the bacterial and fungal communities showed opposite trends, as the transitional regime had the highest bacterial but lowest fungal diversities. Stochastic processes, dominated by dispersal limitation, determined fungal community assembly, whereas deterministic processes, especially variable selection, shaped the bacterial community. The highest number of species–environment interactions and proportion of intra‐kingdom interactions were observed in the co‐occurrence network of the transitional regime; however, this network had the lowest proportion of inter‐kingdom (bacteria–fungi) interactions among the three lake regional regimes. Furthermore, the macrophyte‐dominated regime was observed to have the most complex network structure and maintain the highest microbial community stability. The rhizosphere of Phragmites australis enhanced the inter‐kingdom interactions of bacterial and fungal communities. These findings provide a preliminary ecological perspective for understanding the hysteresis of regimes in response to environmental stress at the microbial community level and emphasize the importance of distinguishing ecologically distinct microbial taxa in future studies focused on alternative stable states.
{"title":"How ecological regimes and emergent macrophytes determine sediment microbial communities: A new insight into typical eutrophic shallow lakes","authors":"Rujia He, Dayong Zhao, Qi Zhou, Qinglong L. Wu, Jin Zeng","doi":"10.1002/lno.12799","DOIUrl":"https://doi.org/10.1002/lno.12799","url":null,"abstract":"Understanding the response of microbial communities to different ecological regimes in eutrophic lakes and the underlying assembly mechanisms is of great significance for revealing the biodiversity maintenance mechanisms of lake ecosystems under alternative stable states. However, our current understanding of the response of sediment microbial communities under emergent macrophytes to regime shifts remains limited. Here, we demonstrated, for the first time, the asynchronous variations of littoral sediment bacterial and fungal communities, regarding the microbial diversities, assembly mechanisms, and inter‐kingdom interactions across three lake regional regimes: macrophyte‐dominated, transitional, and phytoplankton‐dominated. We found the alpha diversities of the bacterial and fungal communities showed opposite trends, as the transitional regime had the highest bacterial but lowest fungal diversities. Stochastic processes, dominated by dispersal limitation, determined fungal community assembly, whereas deterministic processes, especially variable selection, shaped the bacterial community. The highest number of species–environment interactions and proportion of intra‐kingdom interactions were observed in the co‐occurrence network of the transitional regime; however, this network had the lowest proportion of inter‐kingdom (bacteria–fungi) interactions among the three lake regional regimes. Furthermore, the macrophyte‐dominated regime was observed to have the most complex network structure and maintain the highest microbial community stability. The rhizosphere of <jats:italic>Phragmites australis</jats:italic> enhanced the inter‐kingdom interactions of bacterial and fungal communities. These findings provide a preliminary ecological perspective for understanding the hysteresis of regimes in response to environmental stress at the microbial community level and emphasize the importance of distinguishing ecologically distinct microbial taxa in future studies focused on alternative stable states.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"103 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142992337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Issue Information & TOC","authors":"","doi":"10.1002/lno.12806","DOIUrl":"10.1002/lno.12806","url":null,"abstract":"","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"70 1","pages":"iii"},"PeriodicalIF":3.8,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.12806","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142991601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Issue Information & Copyright","authors":"","doi":"10.1002/lno.12805","DOIUrl":"10.1002/lno.12805","url":null,"abstract":"","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"70 1","pages":"ii"},"PeriodicalIF":3.8,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.12805","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142991603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Issue Information & Masthead","authors":"","doi":"10.1002/lno.12804","DOIUrl":"10.1002/lno.12804","url":null,"abstract":"","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"70 1","pages":"i"},"PeriodicalIF":3.8,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.12804","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142991600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Issue Information & Members","authors":"","doi":"10.1002/lno.12807","DOIUrl":"10.1002/lno.12807","url":null,"abstract":"","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"70 1","pages":"iv"},"PeriodicalIF":3.8,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/lno.12807","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142991602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sami Johan Taipale, Cyril Rigaud, Marco Lucas Calderini, Harri Asikainen, Jaakko Juhani Litmanen, Jussi Severi Vesamäki, Mzime Regina Ndebele‐Murisa, Tamuka Nhiwatiwa
Essential biomolecules, such as physiologically essential fatty acids, can critically influence consumers' performance and the ecosystem's functioning. Eicosapentaenoic (EPA; 20:5ω3) and docosahexaenoic (DHA; 22:6ω3) fatty acids are physiologically crucial for consumers, and they must be either obtained from the diet or bioconverted from precursors. We monitored the synthesis of EPA and DHA by primary producers in the largest man‐made ecosystem (Lake Kariba) and in situ fatty acid production, trophic transfer, and endogenous production of EPA and DHA in the tropical lake food web using 13C‐labeling, compound‐specific isotopes, and gene expression of fads2 and elovl5 genes in most abundant fish species. Seston pigment analysis and 23S rRNA sequencing revealed that cyanobacteria dominated primary producers throughout three seasons, and the biosynthesis rate of EPA and DHA was under the detection limit. Moreover, due to the low zooplankton densities and EPA and DHA content in zooplankton, the transfer of EPA and DHA from phytoplankton–zooplankton to upper trophic levels is low. The low production of EPA and DHA by primary producers is mitigated by bioconversion of α‐linolenic acid to EPA and DHA in two tilapia species, especially by Nile tilapia (Oreochromis niloticus) known to feed on cyanobacteria. Compound‐specific isotope analysis revealed that tigerfish (Hydrocynus vittatus), the main predatory fish on the lake, was more closely related to Nile tilapia than to lake planktivorous fish (Limnothrissa miodon). Therefore, trophic interaction between cyanobacteria and algivorous fish has replaced traditional phytoplankton and zooplankton trophic interaction in the synthesis and transfer of EPA and DHA to upper trophic levels.
必需的生物大分子，如生理必需脂肪酸，可对消费者的表现和生态系统的功能产生重要影响。二十碳五烯酸（EPA；20:5ω3）和二十二碳六烯酸（DHA；22:6ω3）脂肪酸在生理上对消费者至关重要，它们必须从食物中获取或从前体生物转化而来。我们在最大的人造生态系统（卡里巴湖）中监测了初级生产者合成 EPA 和 DHA 的情况，并利用 13C 标记、化合物特异性同位素以及最丰富鱼类物种中 fads2 和 elovl5 基因的基因表达，监测了热带湖泊食物网中脂肪酸的原位生产、营养转移以及 EPA 和 DHA 的内源生产。沉积物色素分析和 23S rRNA 测序显示，蓝藻在三个季节中都是主要的初级生产者，EPA 和 DHA 的生物合成率低于检测限。此外，由于浮游动物密度和浮游动物中的 EPA 和 DHA 含量较低，EPA 和 DHA 从浮游植物-浮游动物向上层营养级的转移率较低。两种罗非鱼，尤其是以蓝藻为食的尼罗罗非鱼（Oreochromis niloticus），通过将α-亚麻酸生物转化为 EPA 和 DHA，缓解了初级生产者 EPA 和 DHA 产量低的问题。化合物特异性同位素分析表明，虎鱼（Hydrocynus vittatus）是湖中的主要掠食性鱼类，与尼罗罗非鱼的亲缘关系比与湖中食板鱼（Limnothrissa miodon）的亲缘关系更为密切。因此，在 EPA 和 DHA 的合成以及向上层营养级转移的过程中，蓝藻与食藻鱼类之间的营养相互作用取代了传统的浮游植物与浮游动物之间的营养相互作用。
{"title":"Production and transfer of essential fatty acids in a man‐made tropical lake ecosystem","authors":"Sami Johan Taipale, Cyril Rigaud, Marco Lucas Calderini, Harri Asikainen, Jaakko Juhani Litmanen, Jussi Severi Vesamäki, Mzime Regina Ndebele‐Murisa, Tamuka Nhiwatiwa","doi":"10.1002/lno.12793","DOIUrl":"https://doi.org/10.1002/lno.12793","url":null,"abstract":"Essential biomolecules, such as physiologically essential fatty acids, can critically influence consumers' performance and the ecosystem's functioning. Eicosapentaenoic (EPA; 20:5ω3) and docosahexaenoic (DHA; 22:6ω3) fatty acids are physiologically crucial for consumers, and they must be either obtained from the diet or bioconverted from precursors. We monitored the synthesis of EPA and DHA by primary producers in the largest man‐made ecosystem (Lake Kariba) and in situ fatty acid production, trophic transfer, and endogenous production of EPA and DHA in the tropical lake food web using <jats:sup>13</jats:sup>C‐labeling, compound‐specific isotopes, and gene expression of <jats:italic>fads2</jats:italic> and <jats:italic>elovl5</jats:italic> genes in most abundant fish species. Seston pigment analysis and 23S rRNA sequencing revealed that cyanobacteria dominated primary producers throughout three seasons, and the biosynthesis rate of EPA and DHA was under the detection limit. Moreover, due to the low zooplankton densities and EPA and DHA content in zooplankton, the transfer of EPA and DHA from phytoplankton–zooplankton to upper trophic levels is low. The low production of EPA and DHA by primary producers is mitigated by bioconversion of α‐linolenic acid to EPA and DHA in two tilapia species, especially by Nile tilapia (<jats:italic>Oreochromis niloticus</jats:italic>) known to feed on cyanobacteria. Compound‐specific isotope analysis revealed that tigerfish (<jats:italic>Hydrocynus vittatus</jats:italic>), the main predatory fish on the lake, was more closely related to Nile tilapia than to lake planktivorous fish (<jats:italic>Limnothrissa miodon</jats:italic>). Therefore, trophic interaction between cyanobacteria and algivorous fish has replaced traditional phytoplankton and zooplankton trophic interaction in the synthesis and transfer of EPA and DHA to upper trophic levels.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"26 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A highly resolved time series of dissolved major element (calcium, strontium, magnesium, and lithium) concentrations in the north Gulf of Aqaba, Red Sea, reveals variability in major cation concentrations beyond analytic uncertainties. This variability is composed of an interannual component that is most important for calcium, and a short‐term daily‐timescale component that is most important for lithium. As evident from covariation in calcium, potential alkalinity, and Sr/Ca, the calcium carbonate cycle of the Gulf of Aqaba is dominated by coral calcification, and there was an increase in calcification rates between 2017 and 2018. Variability in lithium concentrations, and larger changes in magnesium concentrations than expected from magnesium distribution coefficients in carbonate minerals, suggest an active cycle of aluminosilicate mineral dissolution, and precipitation of secondary silicate minerals.
{"title":"Dynamics of marine inorganic carbon and silica: A field study of the mechanisms controlling seawater major element concentrations","authors":"Zvi Steiner, Tal Benaltabet, Adi Torfstein","doi":"10.1002/lno.12781","DOIUrl":"https://doi.org/10.1002/lno.12781","url":null,"abstract":"A highly resolved time series of dissolved major element (calcium, strontium, magnesium, and lithium) concentrations in the north Gulf of Aqaba, Red Sea, reveals variability in major cation concentrations beyond analytic uncertainties. This variability is composed of an interannual component that is most important for calcium, and a short‐term daily‐timescale component that is most important for lithium. As evident from covariation in calcium, potential alkalinity, and Sr/Ca, the calcium carbonate cycle of the Gulf of Aqaba is dominated by coral calcification, and there was an increase in calcification rates between 2017 and 2018. Variability in lithium concentrations, and larger changes in magnesium concentrations than expected from magnesium distribution coefficients in carbonate minerals, suggest an active cycle of aluminosilicate mineral dissolution, and precipitation of secondary silicate minerals.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"25 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anika Happe, Bence Buttyán, Bence Gergácz, Silke Langenheder, Stella A. Berger, Jens C. Nejstgaard, Maren Striebel
Climate change is increasing the frequency, intensity, and stochasticity of extreme weather events such as heavy rainfall, storm‐induced mixing, or prolonged drought periods. This results in more variable regimes of dissolved nutrients and carbon in lakes and induces temporal fluctuations in the resource availability for plankton communities, which can further lead to changes in growth and the cellular ratio of essential elements, such as carbon, nitrogen, and phosphorus. However, the current understanding of the effects of variations in regularity and frequency of precipitation events on both producer and consumer levels is limited by the lack of experimental studies examining processes at multiple trophic levels. In our mesocosm study, we added the same total amount of nitrate, phosphate, and colored dissolved organic matter (cDOM) to each mesocosm at pulses differing in frequency (daily, intermittent, or one extreme addition) and regularity (regular, irregular) over a simulated run‐off period followed by a recovery period. Our results showed that phytoplankton biomass fully recovered to control conditions from one extreme nutrient and cDOM pulse, whereas pulses of higher frequency gradually increased the biomass. In terms of stoichiometry, the extreme pulse led to the lowest stability in particulate C : P and N : P ratios. At the zooplankton level, copepod biomass decreased across all nutrient and cDOM additions, but no effects between the treatments were found. Overall, our study demonstrates that phytoplankton stability depends on the regularity and frequency of nutrient additions and differs substantially between biomass and stoichiometry, but the effects may be buffered on zooplankton level.
{"title":"Nutrient pulse scenarios drive contrasting patterns in the functional stability of freshwater phytoplankton","authors":"Anika Happe, Bence Buttyán, Bence Gergácz, Silke Langenheder, Stella A. Berger, Jens C. Nejstgaard, Maren Striebel","doi":"10.1002/lno.12782","DOIUrl":"https://doi.org/10.1002/lno.12782","url":null,"abstract":"Climate change is increasing the frequency, intensity, and stochasticity of extreme weather events such as heavy rainfall, storm‐induced mixing, or prolonged drought periods. This results in more variable regimes of dissolved nutrients and carbon in lakes and induces temporal fluctuations in the resource availability for plankton communities, which can further lead to changes in growth and the cellular ratio of essential elements, such as carbon, nitrogen, and phosphorus. However, the current understanding of the effects of variations in regularity and frequency of precipitation events on both producer and consumer levels is limited by the lack of experimental studies examining processes at multiple trophic levels. In our mesocosm study, we added the same total amount of nitrate, phosphate, and colored dissolved organic matter (cDOM) to each mesocosm at pulses differing in frequency (daily, intermittent, or one extreme addition) and regularity (regular, irregular) over a simulated run‐off period followed by a recovery period. Our results showed that phytoplankton biomass fully recovered to control conditions from one extreme nutrient and cDOM pulse, whereas pulses of higher frequency gradually increased the biomass. In terms of stoichiometry, the extreme pulse led to the lowest stability in particulate C : P and N : P ratios. At the zooplankton level, copepod biomass decreased across all nutrient and cDOM additions, but no effects between the treatments were found. Overall, our study demonstrates that phytoplankton stability depends on the regularity and frequency of nutrient additions and differs substantially between biomass and stoichiometry, but the effects may be buffered on zooplankton level.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"23 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142989414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaona Chen, Tiezhu Mi, Zhigang Yu, Fuxia Yang, Ke Wang, Shasha Zhang, Yinan Zhang, Liping Yuan, Qingzhen Yao
Upwelling in the South Yellow Sea is a phenomenon that plays an important role in nutrient transport and biological productivity. Based on remote sensing data from 2000 to 2022 and in situ observations from 2012 to 2022, we investigated the interannual variability of cold‐water mass frontal upwelling and its contribution to the transport of nutrients in the South Yellow Sea. The results showed that the upwelling positions during summer were consistent with the fronts of the cold‐water masses. The influence of upwelling on nutrient distribution and transport varied interannually, and the El Niño‐Southern Oscillation during winter might influence the intensity of summer frontal upwelling by modulating summer winds. Nutrient fluxes via upwelling from 2012 to 2022 were estimated: 0.08 × 108–25.9 × 108 mol month−1 of dissolved inorganic nitrogen, 0.003 × 108–0.67 × 108 mol month−1 of dissolved inorganic phosphate, and 0.12 × 108–40.8 × 108 mol month−1 of dissolved silicate. Nutrient fluxes during summer were comparable to the summer inputs from the Changjiang River. The dissolved inorganic nitrogen/dissolved inorganic phosphate ratio in frontal upwelling decreased from 38.6 in 2012 to 20.0 in 2022, and the dissolved silicate/dissolved inorganic nitrogen ratio increased from 0.93 in 2012 to 2.48 in 2022. Nutrient composition and fluxes carried by upwelling can alleviate the limitations of both phosphorus and silicon in the South Yellow Sea. Upwelling nutrients in the frontal zone of the Yellow Sea Cold Water Mass could promote local phytoplankton growth and contribute to the development of Ulva prolifera.
{"title":"Upwelling of cold water in the South Yellow Sea alleviates phosphorus and silicon limitations","authors":"Xiaona Chen, Tiezhu Mi, Zhigang Yu, Fuxia Yang, Ke Wang, Shasha Zhang, Yinan Zhang, Liping Yuan, Qingzhen Yao","doi":"10.1002/lno.12784","DOIUrl":"https://doi.org/10.1002/lno.12784","url":null,"abstract":"Upwelling in the South Yellow Sea is a phenomenon that plays an important role in nutrient transport and biological productivity. Based on remote sensing data from 2000 to 2022 and in situ observations from 2012 to 2022, we investigated the interannual variability of cold‐water mass frontal upwelling and its contribution to the transport of nutrients in the South Yellow Sea. The results showed that the upwelling positions during summer were consistent with the fronts of the cold‐water masses. The influence of upwelling on nutrient distribution and transport varied interannually, and the El Niño‐Southern Oscillation during winter might influence the intensity of summer frontal upwelling by modulating summer winds. Nutrient fluxes via upwelling from 2012 to 2022 were estimated: 0.08 × 10<jats:sup>8</jats:sup>–25.9 × 10<jats:sup>8</jats:sup> mol month<jats:sup>−1</jats:sup> of dissolved inorganic nitrogen, 0.003 × 10<jats:sup>8</jats:sup>–0.67 × 10<jats:sup>8</jats:sup> mol month<jats:sup>−1</jats:sup> of dissolved inorganic phosphate, and 0.12 × 10<jats:sup>8</jats:sup>–40.8 × 10<jats:sup>8</jats:sup> mol month<jats:sup>−1</jats:sup> of dissolved silicate. Nutrient fluxes during summer were comparable to the summer inputs from the Changjiang River. The dissolved inorganic nitrogen/dissolved inorganic phosphate ratio in frontal upwelling decreased from 38.6 in 2012 to 20.0 in 2022, and the dissolved silicate/dissolved inorganic nitrogen ratio increased from 0.93 in 2012 to 2.48 in 2022. Nutrient composition and fluxes carried by upwelling can alleviate the limitations of both phosphorus and silicon in the South Yellow Sea. Upwelling nutrients in the frontal zone of the Yellow Sea Cold Water Mass could promote local phytoplankton growth and contribute to the development of <jats:italic>Ulva prolifera</jats:italic>.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"24 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142989593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ze Chen, Wenqian Xie, Sven Kranz, Haizheng Hong, Dalin Shi
Iron (Fe) and phosphorus (P) availability constrain the growth and N2 fixation of diazotrophic cyanobacteria in the global ocean. However, how Fe and P limitation may modulate the effects of ocean acidification on the unicellular diazotrophic cyanobacterium Crocosphaera remains largely unknown. Here, we examined the physiological responses of Crocosphaera watsonii WH8501 to CO2 enrichment under both nutrient‐replete and steadily Fe‐ or P‐limited conditions. Increased CO2 (750 μatm vs. 400 μatm) reduced the growth and N2 fixation rates of Crocosphaera, with Fe limitation intensifying the negative effect, whereas CO2 enrichment had a minimal impact under P limitation. Mechanistically, the high CO2 treatment may have led to a reallocation of limited Fe to nitrogenase synthesis to compensate for the reduction in nitrogenase efficiency caused by low pH; consequently, other Fe‐requiring metabolic pathways, such as respiration and photosynthesis, were impaired, which in turn amplified the negative effects of acidification. Conversely, under P limitation, CO2 enrichment had little or no effect on cellular P allocation among major P‐containing molecules (polyphosphate, phospholipids, DNA, and RNA). Cell volumes were significantly reduced in P‐limited and high CO2 cultures, which increased the surface : volume ratio and could facilitate nutrient uptake, thereby alleviating some of the negative effect of acidification on N2 fixation. These findings highlight the distinct responses of Crocosphaera to high CO2 under different nutrient conditions, improving a predictive understanding of global N2 fixation in future acidified oceans.
铁（Fe）和磷（P）的供应制约着全球海洋中重氮蓝藻的生长和氮固定。然而，铁和磷的限制如何调节海洋酸化对单细胞重氮蓝藻Crocosphaera的影响在很大程度上仍是未知数。在此，我们研究了Crocosphaera watsonii WH8501在养分充足和稳定的铁或磷限制条件下对二氧化碳富集的生理反应。二氧化碳浓度的增加（750 μatm vs. 400 μatm）降低了Crocosphaera的生长和N2固定率，铁限制加剧了这种负面影响，而在磷限制条件下，二氧化碳富集的影响很小。从机理上讲，高浓度 CO2 处理可能导致有限的铁元素重新分配到氮酶合成中，以补偿低 pH 值导致的氮酶效率降低；因此，其他需要铁元素的代谢途径（如呼吸作用和光合作用）受到损害，这反过来又扩大了酸化的负面影响。相反，在P限制条件下，CO2富集对细胞中主要含P分子（多聚磷酸盐、磷脂、DNA和RNA）的P分配几乎没有影响。在 P 限制和高 CO2 培养物中，细胞体积明显缩小，这增加了表面与体积之比，可促进养分吸收，从而减轻酸化对 N2 固定的一些负面影响。这些发现突显了Crocosphaera在不同营养条件下对高CO2的不同反应，提高了对未来酸化海洋中全球N2固定的预测性理解。
{"title":"Iron and phosphorus limitations modulate the effects of carbon dioxide enrichment on a unicellular nitrogen‐fixing cyanobacterium","authors":"Ze Chen, Wenqian Xie, Sven Kranz, Haizheng Hong, Dalin Shi","doi":"10.1002/lno.12780","DOIUrl":"https://doi.org/10.1002/lno.12780","url":null,"abstract":"Iron (Fe) and phosphorus (P) availability constrain the growth and N<jats:sub>2</jats:sub> fixation of diazotrophic cyanobacteria in the global ocean. However, how Fe and P limitation may modulate the effects of ocean acidification on the unicellular diazotrophic cyanobacterium <jats:italic>Crocosphaera</jats:italic> remains largely unknown. Here, we examined the physiological responses of <jats:italic>Crocosphaera watsonii</jats:italic> WH8501 to CO<jats:sub>2</jats:sub> enrichment under both nutrient‐replete and steadily Fe‐ or P‐limited conditions. Increased CO<jats:sub>2</jats:sub> (750 <jats:italic>μ</jats:italic>atm vs. 400 <jats:italic>μ</jats:italic>atm) reduced the growth and N<jats:sub>2</jats:sub> fixation rates of <jats:italic>Crocosphaera</jats:italic>, with Fe limitation intensifying the negative effect, whereas CO<jats:sub>2</jats:sub> enrichment had a minimal impact under P limitation. Mechanistically, the high CO<jats:sub>2</jats:sub> treatment may have led to a reallocation of limited Fe to nitrogenase synthesis to compensate for the reduction in nitrogenase efficiency caused by low pH; consequently, other Fe‐requiring metabolic pathways, such as respiration and photosynthesis, were impaired, which in turn amplified the negative effects of acidification. Conversely, under P limitation, CO<jats:sub>2</jats:sub> enrichment had little or no effect on cellular P allocation among major P‐containing molecules (polyphosphate, phospholipids, DNA, and RNA). Cell volumes were significantly reduced in P‐limited and high CO<jats:sub>2</jats:sub> cultures, which increased the surface : volume ratio and could facilitate nutrient uptake, thereby alleviating some of the negative effect of acidification on N<jats:sub>2</jats:sub> fixation. These findings highlight the distinct responses of <jats:italic>Crocosphaera</jats:italic> to high CO<jats:sub>2</jats:sub> under different nutrient conditions, improving a predictive understanding of global N<jats:sub>2</jats:sub> fixation in future acidified oceans.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"44 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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