{"title":"细菌叶绿素揭示了河口缺氧和无氧光合固碳作用","authors":"Jiawei Kan, Liqin Duan, Jinming Song, Meiling Yin, Xuegang Li, Xiaoqi Liu, Huamao Yuan, Yingxia Wang","doi":"10.1002/lno.70203","DOIUrl":null,"url":null,"abstract":"Bacteriochlorophylls (Bchls) are photosynthetic pigments produced by aerobic anoxygenic photosynthetic bacteria and anoxygenic photosynthetic bacteria. However, the sources, degradation, and influence of redox conditions in marine environments remain unclear. This study investigated the distribution of Bchls in the Changjiang Estuary to evaluate their origins, degradation, and environmental response. Results showed that total bacteriochlorophylls <jats:italic>a</jats:italic> (T<jats:sub>Bchl<jats:italic>a</jats:italic></jats:sub>), including bacteriochlorophyll <jats:italic>a</jats:italic> (Bchl <jats:italic>a</jats:italic>) and its degradation product bacteriopheophytin <jats:italic>a</jats:italic> (Bphe <jats:italic>a</jats:italic>), were higher in surface waters than in bottom waters in the inner estuary, where microbial evidence (<jats:italic>Sphingomonadaceae</jats:italic>) identified aerobic anoxygenic photosynthetic bacteria as the dominant source of T<jats:sub>Bchl<jats:italic>a</jats:italic></jats:sub>. In contrast, the outer estuary exhibited elevated T<jats:sub>Bchl<jats:italic>a</jats:italic></jats:sub> in bottom waters, with purple sulfur bacteria (<jats:italic>Chromatiaceae</jats:italic> and <jats:italic>Ectothiorhodospiraceae</jats:italic>) as the primary contributors. Significant negative correlations between Bphe <jats:italic>a</jats:italic> concentrations in bottom seawaters and surface sediments and the dissolved oxygen levels in bottom waters, along with a positive correlation between Bphe <jats:italic>a</jats:italic> in the surface sediments and the salinity difference between bottom and surface seawaters (Δ<jats:italic>S</jats:italic>), suggest that Bphe <jats:italic>a</jats:italic> may serve as a useful indicator of hypoxia and water stratification. The contribution of anoxygenic photosynthetic bacteria to carbon fixation is expected to increase notably, potentially reaching 16% of phytoplankton carbon fixation after 100 years under expanding hypoxia. These findings establish Bchls as reliable indicators of hypoxia and water stratification and provide a framework for reevaluating carbon fixation in global hypoxic coastal systems.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"274 1","pages":""},"PeriodicalIF":3.7000,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Bacteriochlorophyll reveals estuarine hypoxia and anoxygenic photosynthetic carbon fixation\",\"authors\":\"Jiawei Kan, Liqin Duan, Jinming Song, Meiling Yin, Xuegang Li, Xiaoqi Liu, Huamao Yuan, Yingxia Wang\",\"doi\":\"10.1002/lno.70203\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Bacteriochlorophylls (Bchls) are photosynthetic pigments produced by aerobic anoxygenic photosynthetic bacteria and anoxygenic photosynthetic bacteria. However, the sources, degradation, and influence of redox conditions in marine environments remain unclear. This study investigated the distribution of Bchls in the Changjiang Estuary to evaluate their origins, degradation, and environmental response. Results showed that total bacteriochlorophylls <jats:italic>a</jats:italic> (T<jats:sub>Bchl<jats:italic>a</jats:italic></jats:sub>), including bacteriochlorophyll <jats:italic>a</jats:italic> (Bchl <jats:italic>a</jats:italic>) and its degradation product bacteriopheophytin <jats:italic>a</jats:italic> (Bphe <jats:italic>a</jats:italic>), were higher in surface waters than in bottom waters in the inner estuary, where microbial evidence (<jats:italic>Sphingomonadaceae</jats:italic>) identified aerobic anoxygenic photosynthetic bacteria as the dominant source of T<jats:sub>Bchl<jats:italic>a</jats:italic></jats:sub>. In contrast, the outer estuary exhibited elevated T<jats:sub>Bchl<jats:italic>a</jats:italic></jats:sub> in bottom waters, with purple sulfur bacteria (<jats:italic>Chromatiaceae</jats:italic> and <jats:italic>Ectothiorhodospiraceae</jats:italic>) as the primary contributors. Significant negative correlations between Bphe <jats:italic>a</jats:italic> concentrations in bottom seawaters and surface sediments and the dissolved oxygen levels in bottom waters, along with a positive correlation between Bphe <jats:italic>a</jats:italic> in the surface sediments and the salinity difference between bottom and surface seawaters (Δ<jats:italic>S</jats:italic>), suggest that Bphe <jats:italic>a</jats:italic> may serve as a useful indicator of hypoxia and water stratification. The contribution of anoxygenic photosynthetic bacteria to carbon fixation is expected to increase notably, potentially reaching 16% of phytoplankton carbon fixation after 100 years under expanding hypoxia. These findings establish Bchls as reliable indicators of hypoxia and water stratification and provide a framework for reevaluating carbon fixation in global hypoxic coastal systems.\",\"PeriodicalId\":18143,\"journal\":{\"name\":\"Limnology and Oceanography\",\"volume\":\"274 1\",\"pages\":\"\"},\"PeriodicalIF\":3.7000,\"publicationDate\":\"2025-09-02\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Limnology and Oceanography\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://doi.org/10.1002/lno.70203\",\"RegionNum\":1,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"LIMNOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Limnology and Oceanography","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1002/lno.70203","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"LIMNOLOGY","Score":null,"Total":0}
Bacteriochlorophyll reveals estuarine hypoxia and anoxygenic photosynthetic carbon fixation
Bacteriochlorophylls (Bchls) are photosynthetic pigments produced by aerobic anoxygenic photosynthetic bacteria and anoxygenic photosynthetic bacteria. However, the sources, degradation, and influence of redox conditions in marine environments remain unclear. This study investigated the distribution of Bchls in the Changjiang Estuary to evaluate their origins, degradation, and environmental response. Results showed that total bacteriochlorophylls a (TBchla), including bacteriochlorophyll a (Bchl a) and its degradation product bacteriopheophytin a (Bphe a), were higher in surface waters than in bottom waters in the inner estuary, where microbial evidence (Sphingomonadaceae) identified aerobic anoxygenic photosynthetic bacteria as the dominant source of TBchla. In contrast, the outer estuary exhibited elevated TBchla in bottom waters, with purple sulfur bacteria (Chromatiaceae and Ectothiorhodospiraceae) as the primary contributors. Significant negative correlations between Bphe a concentrations in bottom seawaters and surface sediments and the dissolved oxygen levels in bottom waters, along with a positive correlation between Bphe a in the surface sediments and the salinity difference between bottom and surface seawaters (ΔS), suggest that Bphe a may serve as a useful indicator of hypoxia and water stratification. The contribution of anoxygenic photosynthetic bacteria to carbon fixation is expected to increase notably, potentially reaching 16% of phytoplankton carbon fixation after 100 years under expanding hypoxia. These findings establish Bchls as reliable indicators of hypoxia and water stratification and provide a framework for reevaluating carbon fixation in global hypoxic coastal systems.
期刊介绍:
Limnology and Oceanography (L&O; print ISSN 0024-3590, online ISSN 1939-5590) publishes original articles, including scholarly reviews, about all aspects of limnology and oceanography. The journal''s unifying theme is the understanding of aquatic systems. Submissions are judged on the originality of their data, interpretations, and ideas, and on the degree to which they can be generalized beyond the particular aquatic system examined. Laboratory and modeling studies must demonstrate relevance to field environments; typically this means that they are bolstered by substantial "real-world" data. Few purely theoretical or purely empirical papers are accepted for review.