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2026, 48(1): 1-3.
Abstract:
2026, 48(1): 1-29.
doi: 10.12284/hyxb2026008
Abstract:
China’s marine waters support abundant sea cucumber resources, with 138 species recorded across 7 orders, 16 families and 61 genera, including 39 species of major nutritional and economic value. These species are widely distributed across tropical, subtropical, and temperate waters, where they play essential roles in maintaining benthic ecological processes, regulating sediment structure, and supporting the development of marine ranching systems. At present, research on sea cucumbers in China has largely focused on aquaculture techniques and the bioactive properties of functional compounds, whereas fundamental studies on taxonomy and systematics remain comparatively limited. Since the establishment of the sea cucumber classification system in the 19th century, taxonomic methodologies have undergone a profound shift from traditional morphology-based approaches to modern molecular systematics. Traditional taxonomy relies primarily on external morphology and ossicle characteristics, with as many as 25 recognized ossicle types. However, the complexity of ossicle structures, the pronounced morphological polymorphism, and the high interspecific similarity and substantial intraspecific variation collectively hinder precise identification of closely related taxa and individuals at different life-history stages when using morphology alone.In recent years, the widespread application of molecular barcoding techniques such as COI and 16S rRNA, together with the rapid development of mitogenomic and whole-genome phylogenetic approaches, has significantly improved the accuracy of species identification and phylogenetic reconstruction. Despite these advances, several challenges persist, including insufficient deep-sea and South China Sea sampling, incomplete specimen coverage, limited molecular datasets, and inconsistent identification standards. Future research should strengthen systematic sampling and long-term monitoring in key marine regions, establish an integrative taxonomic framework combining traditional morphological traits, ossicle microstructure, and multi-gene molecular data, and promote the adoption of environmental DNA (eDNA) non-invasive sampling and AI-assisted digital imaging platforms. The establishment of standardized genetic and morphological databases, together with a national DNA barcode library, will provide essential technical support for rapid species identification and sustainable resource management. This study comprehensively reviews the species diversity patterns and taxonomic progress of Chinese sea cucumbers, identifies the current challenges in holothurian taxonomy, and proposes future directions toward a robust classification framework that underpins biodiversity conservation, ecological restoration, and the sustainable utilization of sea cucumber resources.
China’s marine waters support abundant sea cucumber resources, with 138 species recorded across 7 orders, 16 families and 61 genera, including 39 species of major nutritional and economic value. These species are widely distributed across tropical, subtropical, and temperate waters, where they play essential roles in maintaining benthic ecological processes, regulating sediment structure, and supporting the development of marine ranching systems. At present, research on sea cucumbers in China has largely focused on aquaculture techniques and the bioactive properties of functional compounds, whereas fundamental studies on taxonomy and systematics remain comparatively limited. Since the establishment of the sea cucumber classification system in the 19th century, taxonomic methodologies have undergone a profound shift from traditional morphology-based approaches to modern molecular systematics. Traditional taxonomy relies primarily on external morphology and ossicle characteristics, with as many as 25 recognized ossicle types. However, the complexity of ossicle structures, the pronounced morphological polymorphism, and the high interspecific similarity and substantial intraspecific variation collectively hinder precise identification of closely related taxa and individuals at different life-history stages when using morphology alone.In recent years, the widespread application of molecular barcoding techniques such as COI and 16S rRNA, together with the rapid development of mitogenomic and whole-genome phylogenetic approaches, has significantly improved the accuracy of species identification and phylogenetic reconstruction. Despite these advances, several challenges persist, including insufficient deep-sea and South China Sea sampling, incomplete specimen coverage, limited molecular datasets, and inconsistent identification standards. Future research should strengthen systematic sampling and long-term monitoring in key marine regions, establish an integrative taxonomic framework combining traditional morphological traits, ossicle microstructure, and multi-gene molecular data, and promote the adoption of environmental DNA (eDNA) non-invasive sampling and AI-assisted digital imaging platforms. The establishment of standardized genetic and morphological databases, together with a national DNA barcode library, will provide essential technical support for rapid species identification and sustainable resource management. This study comprehensively reviews the species diversity patterns and taxonomic progress of Chinese sea cucumbers, identifies the current challenges in holothurian taxonomy, and proposes future directions toward a robust classification framework that underpins biodiversity conservation, ecological restoration, and the sustainable utilization of sea cucumber resources.
2026, 48(1): 42-55.
doi: 10.12284/hyxb2026006
Abstract:
In this study, two fibroblast growth factor (FGF) genes, named as PdFGF1 and PdFGF17, were identified and cloned from the coral Pocillopora damicornis. Sequence analysis showed that PdFGF1 and PdFGF17 encode 195 and 149 amino acids, respectively. Both contain a signal peptide and a typical FGF domain, with characteristic β-sheets and η-loops in their topological structures. The FGF family in higher animals can be divided into seven subfamilies (FGF1, FGF4, FGF7, FGF8, FGF9, FGF11, and FGF19). Multiple sequence alignment and phylogenetic analysis revealed that PdFGF1 belongs to the FGF1 subfamily, sharing 30.15% sequence identity with HsFGF1 (Homo sapiens), whereas PdFGF17 clusters with the FGF8 subfamily, sharing 29.36% identity with HsFGF17. To further elucidate their biological roles, transcriptomic analysis was performed on P. damicornis under heat stress induced polyp bailout. The results showed that the expression levels of FGF family genes (PdFGF1, PdFGF2, PdFGF9, PdFGF17, PdFGF18, PdFGFR1, PdFGFR2, PdFGFR3 and PdFGFR4) were significantly upregulated during the detachment process. Moreover, the FGF signaling pathway was found to activate the downstream Ras/MAPK cascade, thereby regulating cytoskeletal remodeling and cell adhesion. Gene co-expression network analysis using Cytoscape further revealed significant co-expression relationships between FGF genes and extracellular matrix (ECM) degrading genes in the coenosarc tissue, including ADAMTSs, COL21A1, CTSZ, and P4HA. Collectively, these findings suggest that heat stress activates the FGF signaling pathway in P. damicornis, promoting ECM degradation and ultimately mediating coenosarc dissociation and polyp bailout.
In this study, two fibroblast growth factor (FGF) genes, named as PdFGF1 and PdFGF17, were identified and cloned from the coral Pocillopora damicornis. Sequence analysis showed that PdFGF1 and PdFGF17 encode 195 and 149 amino acids, respectively. Both contain a signal peptide and a typical FGF domain, with characteristic β-sheets and η-loops in their topological structures. The FGF family in higher animals can be divided into seven subfamilies (FGF1, FGF4, FGF7, FGF8, FGF9, FGF11, and FGF19). Multiple sequence alignment and phylogenetic analysis revealed that PdFGF1 belongs to the FGF1 subfamily, sharing 30.15% sequence identity with HsFGF1 (Homo sapiens), whereas PdFGF17 clusters with the FGF8 subfamily, sharing 29.36% identity with HsFGF17. To further elucidate their biological roles, transcriptomic analysis was performed on P. damicornis under heat stress induced polyp bailout. The results showed that the expression levels of FGF family genes (PdFGF1, PdFGF2, PdFGF9, PdFGF17, PdFGF18, PdFGFR1, PdFGFR2, PdFGFR3 and PdFGFR4) were significantly upregulated during the detachment process. Moreover, the FGF signaling pathway was found to activate the downstream Ras/MAPK cascade, thereby regulating cytoskeletal remodeling and cell adhesion. Gene co-expression network analysis using Cytoscape further revealed significant co-expression relationships between FGF genes and extracellular matrix (ECM) degrading genes in the coenosarc tissue, including ADAMTSs, COL21A1, CTSZ, and P4HA. Collectively, these findings suggest that heat stress activates the FGF signaling pathway in P. damicornis, promoting ECM degradation and ultimately mediating coenosarc dissociation and polyp bailout.
2026, 48(1): 56-63.
doi: 10.12284/hyxb2026010
Abstract:
In order to study the biological characteristics of Rhopilema esculentum and its environmental influencing factors, this study analyzed the biological characteristics of R.esculentum in different years according to the monitoring data of R. esculentum resources in Shengsi sea area of Hangzhou Bay from June to July 2022 to 2024, and explored the relationship between the umbrella diameter, body weight and environmental influencing factors of R. esculentum by GAM model. The results showed that there were significant differences between umbrella diameter and body weight of R.esculentum before the special fishing permits during the summer fishing moratorium, and the growth rate of R. esculentum body weight showed different growth trends at different growth stages. The results of the GAM showed that umbrella diameter and body weight of R. esculentum increased gradually with the increase of sea surface temperature from 21.18℃ to 26.81℃. Sea surface salinity has a significant effect on the growth of R. esculentum umbrella diameter. In the salinity range of 9.3−25.2, the umbrella diameter of R. esculentum increases, and the optimum salinity is 17.7−22.7. In the interaction between sea surface temperature and salinity, the high value area of umbrella diameter and the middle value area of body weight of R. esculentum are in the range of sea surface temperature 24−26.3℃ and sea surface salinity 15−22. There were significant differences in umbrella diameter and body weight among years after the special fishing permits during the summer fishing moratorium. Comprehensive analysis showed that the growth of umbrella diameter and body weight of R. esculentum was affected by sea surface temperature and salinity, and the initial fishing time could be determined based on the level of sea surface temperature.
In order to study the biological characteristics of Rhopilema esculentum and its environmental influencing factors, this study analyzed the biological characteristics of R.esculentum in different years according to the monitoring data of R. esculentum resources in Shengsi sea area of Hangzhou Bay from June to July 2022 to 2024, and explored the relationship between the umbrella diameter, body weight and environmental influencing factors of R. esculentum by GAM model. The results showed that there were significant differences between umbrella diameter and body weight of R.esculentum before the special fishing permits during the summer fishing moratorium, and the growth rate of R. esculentum body weight showed different growth trends at different growth stages. The results of the GAM showed that umbrella diameter and body weight of R. esculentum increased gradually with the increase of sea surface temperature from 21.18℃ to 26.81℃. Sea surface salinity has a significant effect on the growth of R. esculentum umbrella diameter. In the salinity range of 9.3−25.2, the umbrella diameter of R. esculentum increases, and the optimum salinity is 17.7−22.7. In the interaction between sea surface temperature and salinity, the high value area of umbrella diameter and the middle value area of body weight of R. esculentum are in the range of sea surface temperature 24−26.3℃ and sea surface salinity 15−22. There were significant differences in umbrella diameter and body weight among years after the special fishing permits during the summer fishing moratorium. Comprehensive analysis showed that the growth of umbrella diameter and body weight of R. esculentum was affected by sea surface temperature and salinity, and the initial fishing time could be determined based on the level of sea surface temperature.
2026, 48(1): 64-82.
doi: 10.12284/hyxb2026016
Abstract:
To investigate the resource utilization and interspecific relationships of macrobenthic fauna in the rocky intertidal zones of Zhejiang Province, surveys were conducted at 10 rocky intertidal sites from March 2024 to April 2025. The index of relative importance (IRI), niche breadth (Bi), niche overlap (Oik), variance ratio (VR), chi-square test, association coefficient (AC), percentage of co-occurrence (PC), Spearman rank correlation, and redundancy analysis (RDA) were applied to analyze the ecological niches, interspecific associations, and relationships between dominant species and environmental factors. The results showed: (1) the rocky intertidal zones of Zhejiang host a rich diversity of species, with 17 dominant species identified (IRI > 100); (2) Thais clavigera and Nodilittorina exigua had wide niche breadths and were classified as wide niche breadth species, while Chthamalus challengeri and Crassostrea angulata were narrow niche breadth species. (3) significant niche overlap was observed among T. clavigera, Littorina brevicula, Thais luteostoma, and Notoacmea schrenckii, indicating intense resource competition; (4) salinity and chl a were key factors influencing species abundance, and a significant negative correlation was found between salinity and chl a. (5) the community structure of macrobenthos in the rocky intertidal zones appeared to be loosely organized and compositionally unstable, suggesting that it may currently be in a stage of successional recovery.
To investigate the resource utilization and interspecific relationships of macrobenthic fauna in the rocky intertidal zones of Zhejiang Province, surveys were conducted at 10 rocky intertidal sites from March 2024 to April 2025. The index of relative importance (IRI), niche breadth (Bi), niche overlap (Oik), variance ratio (VR), chi-square test, association coefficient (AC), percentage of co-occurrence (PC), Spearman rank correlation, and redundancy analysis (RDA) were applied to analyze the ecological niches, interspecific associations, and relationships between dominant species and environmental factors. The results showed: (1) the rocky intertidal zones of Zhejiang host a rich diversity of species, with 17 dominant species identified (IRI > 100); (2) Thais clavigera and Nodilittorina exigua had wide niche breadths and were classified as wide niche breadth species, while Chthamalus challengeri and Crassostrea angulata were narrow niche breadth species. (3) significant niche overlap was observed among T. clavigera, Littorina brevicula, Thais luteostoma, and Notoacmea schrenckii, indicating intense resource competition; (4) salinity and chl a were key factors influencing species abundance, and a significant negative correlation was found between salinity and chl a. (5) the community structure of macrobenthos in the rocky intertidal zones appeared to be loosely organized and compositionally unstable, suggesting that it may currently be in a stage of successional recovery.
2026, 48(1): 83-96.
doi: 10.12284/hyxb2026018
Abstract:
Isognomonids are widely distributed in the intertidal zones of tropical and subtropical regions, where they play important ecological and economic roles. However, due to significant morphological variability influenced by environmental factors, morphology-based taxonomic classifications of Isognomonidae remain contentious. In this study, mitochondrial COI sequences were obtained from specimens of Isognomonidae collected along the Guangdong coast, supplemented with homologous sequences retrieved from GenBank to construct phylogenetic trees, and DNA molecular barcoding techniques been applied to analyze the species of Isognomonidae distributed in the Guangdong coast. Results demonstrated strong support for the monophyly of Isognomonidae. A total of 125 COI sequences yielded 68 haplotypes, which clustered into 16 well-supported species-level units, although their evolutionary relationships remain uncertain. Intraspecific Kimura 2-parameter (K2P) genetic distances ranged from 0 to 0.009, while interspecific distances ranged from 0.029 to 0.595. The average nucleotide composition of the COI fragments showed 55.0% A + T and 45.0% C + G, with variation observed among species. Five species were identified from Guangdong samples, including the previously recorded Isognomon nucleus and four cryptic species. This study confirms that DNA barcoding is an effective tool for supporting and revising the taxonomy of Isognomonidae and reveals cryptic diversity, which is crucial for marine biodiversity conservation.
Isognomonids are widely distributed in the intertidal zones of tropical and subtropical regions, where they play important ecological and economic roles. However, due to significant morphological variability influenced by environmental factors, morphology-based taxonomic classifications of Isognomonidae remain contentious. In this study, mitochondrial COI sequences were obtained from specimens of Isognomonidae collected along the Guangdong coast, supplemented with homologous sequences retrieved from GenBank to construct phylogenetic trees, and DNA molecular barcoding techniques been applied to analyze the species of Isognomonidae distributed in the Guangdong coast. Results demonstrated strong support for the monophyly of Isognomonidae. A total of 125 COI sequences yielded 68 haplotypes, which clustered into 16 well-supported species-level units, although their evolutionary relationships remain uncertain. Intraspecific Kimura 2-parameter (K2P) genetic distances ranged from 0 to 0.009, while interspecific distances ranged from 0.029 to 0.595. The average nucleotide composition of the COI fragments showed 55.0% A + T and 45.0% C + G, with variation observed among species. Five species were identified from Guangdong samples, including the previously recorded Isognomon nucleus and four cryptic species. This study confirms that DNA barcoding is an effective tool for supporting and revising the taxonomy of Isognomonidae and reveals cryptic diversity, which is crucial for marine biodiversity conservation.
2026, 48(1): 97-108.
doi: 10.12284/hyxb2026002
Abstract:
Species of the family Maldanidae are widely distributed across various marine environments, ranging from shallow to deep-sea habitats. However, due to the fragility of their bodies during collection, obtaining intact specimens is often uneasy, and morphological research is difficult to conduct fully. As a result, there are differing viewpoints and ongoing debates among researchers regarding their taxonomic classification. To clarify the evolutionary relationships within Maldanidae, this study assembled and analyzed the complete mitochondrial genome (mitogenome) of Praxillella sp. using second-generation genome sequencing data. The mitogenome of Praxillella sp. is15539 bp in length, with a base composition of A (33.7%), T (32.6%), G (13.6%), and C (20%), showing a pronounced AT bias. Similar to most metazoans, the genome contains 13 protein-coding genes (PCGs), 22 tRNA genes (including a duplicated tRNA-M), two rRNA genes, and a control region (CR). The codon usage is mainly driven by natural selection. The topological structures of the ML tree and the Bayesian tree constructed based on 13 PCGs are almost all consistent, but the position of P. praetermissa within the subfamily Euclymeninae being uncertain. Phylogeny based on the 13 PCGs overall supports the monophyly of Maldaninae, in contrast, no monophyletic clade is formed within Euclymeninae, being paraphyletic with Nicomachinae, Among the 14 analyzed Maldanid species, four types of gene order are identified, three of which involve changes in tRNA arrangements, driven by tandem duplication and random loss mechanisms. The results offer novel insights into in clarification of taxonomy and phylogenetic relationships of Praxillella sp. in Maldanidae.
Species of the family Maldanidae are widely distributed across various marine environments, ranging from shallow to deep-sea habitats. However, due to the fragility of their bodies during collection, obtaining intact specimens is often uneasy, and morphological research is difficult to conduct fully. As a result, there are differing viewpoints and ongoing debates among researchers regarding their taxonomic classification. To clarify the evolutionary relationships within Maldanidae, this study assembled and analyzed the complete mitochondrial genome (mitogenome) of Praxillella sp. using second-generation genome sequencing data. The mitogenome of Praxillella sp. is
2026, 48(1): 109-123.
doi: 10.12284/hyxb2026020
Abstract:
Eodemus subtilis is an intertidal to shallow-water crab species belonging to the family Portunidae (Order: Decapoda), primarily distributed along the southeastern coastal waters of China. In this study, we conducted a comprehensive characterization of its mitochondrial genome using high-throughput sequencing and bioinformatic analyses. The complete mitochondrial genome of E. subtilis is 15,878 bp in length and comprises 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes, and one non-coding control region. Notably, 24 of these genes are encoded on the heavy strand (H-strand). The mitochondrial genome exhibits a strong A + T bias (69.81%), with negative AT-skew (–0.021) and GC-skew (–0.233). Analysis of relative synonymous codon usage (RSCU) revealed that the codons UCU (Ser2) and UUA (Leu2) are highly frequent, with preferred codons predominantly ending in A/T. The gene arrangement in E. subtilis is highly conserved, maintaining the ancestral gene order typical of Brachyura crabs, with no observed rearrangements. Selection pressure analysis (Ka/Ks) of the 13 PCGs across Portunidae crabs indicated that 11 genes (excluding COIII and ND1) underwent purifying selection. Phylogenetic and divergence time estimation analyses demonstrated that E. subtilis forms a clade with Monomia gladiator, with an estimated divergence time of approximately 44.34 million years ago (Ma). These findings provide significant new insights into the evolutionary history and molecular adaptations of E. subtilis within Portunidae, as well as into the evolutionary relationships of Portunidae within Brachyura.
Eodemus subtilis is an intertidal to shallow-water crab species belonging to the family Portunidae (Order: Decapoda), primarily distributed along the southeastern coastal waters of China. In this study, we conducted a comprehensive characterization of its mitochondrial genome using high-throughput sequencing and bioinformatic analyses. The complete mitochondrial genome of E. subtilis is 15,878 bp in length and comprises 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes, and one non-coding control region. Notably, 24 of these genes are encoded on the heavy strand (H-strand). The mitochondrial genome exhibits a strong A + T bias (69.81%), with negative AT-skew (–0.021) and GC-skew (–0.233). Analysis of relative synonymous codon usage (RSCU) revealed that the codons UCU (Ser2) and UUA (Leu2) are highly frequent, with preferred codons predominantly ending in A/T. The gene arrangement in E. subtilis is highly conserved, maintaining the ancestral gene order typical of Brachyura crabs, with no observed rearrangements. Selection pressure analysis (Ka/Ks) of the 13 PCGs across Portunidae crabs indicated that 11 genes (excluding COIII and ND1) underwent purifying selection. Phylogenetic and divergence time estimation analyses demonstrated that E. subtilis forms a clade with Monomia gladiator, with an estimated divergence time of approximately 44.34 million years ago (Ma). These findings provide significant new insights into the evolutionary history and molecular adaptations of E. subtilis within Portunidae, as well as into the evolutionary relationships of Portunidae within Brachyura.
2026, 48(1): 124-136.
doi: 10.12284/hyxb2026022
Abstract:
Mangrove ecosystems play a pivotal role in sustaining coastal ecological stability. However, under the compounded influences of climate change and human disturbance, these ecosystems are experiencing severe degradation. Artificial afforestation has emerged as the predominant restoration strategy. This study focuses on young mangrove plantations along the Guangxi coastline, investigating the ecological strategy differences among various species within these artificial plantations. Utilizing plant functional traits and the CSR (Competitor, Stress-tolerator, Ruderal) strategy theory, the study explores the relationships between functional traits, CSR strategies, and the driving factors behind these ecological patterns. The findings reveal that: (1) There are significant variations in CSR strategies among different species. Aegiceras corniculatum and Kandelia obovata predominantly exhibit the S strategy, Bruguiera gymnorrhiza is more inclined towards the C strategy, while Avicennia marina demonstrates a relatively balanced distribution across the CSR spectrum. (2) A significant correlation exists between CSR strategies and functional trait indicators. Specifically, the C strategy shows a significant positive correlation with chlorophyll content and tree height increment, and a significant negative correlation with leaf phosphorus content. The S strategy is significantly negatively correlated with tree height increment. The R strategy exhibits significant positive correlations with chlorophyll content and tree height increment, and significant negative correlations with leaf nitrogen content and leaf phosphorus content. (3) Flood time and depth are identified as key environmental factors driving the variation in CSR strategies within the young mangrove plantations. This study substantiates the applicability of CSR theory in intertidal artificial mangrove ecosystems, elucidating the mechanistic connections between plant adaptive strategies and ecological niche occupation. The results provide both theoretical insights and practical guidance for optimizing species selection and enhancing the efficiency of mangrove ecosystem restoration.
Mangrove ecosystems play a pivotal role in sustaining coastal ecological stability. However, under the compounded influences of climate change and human disturbance, these ecosystems are experiencing severe degradation. Artificial afforestation has emerged as the predominant restoration strategy. This study focuses on young mangrove plantations along the Guangxi coastline, investigating the ecological strategy differences among various species within these artificial plantations. Utilizing plant functional traits and the CSR (Competitor, Stress-tolerator, Ruderal) strategy theory, the study explores the relationships between functional traits, CSR strategies, and the driving factors behind these ecological patterns. The findings reveal that: (1) There are significant variations in CSR strategies among different species. Aegiceras corniculatum and Kandelia obovata predominantly exhibit the S strategy, Bruguiera gymnorrhiza is more inclined towards the C strategy, while Avicennia marina demonstrates a relatively balanced distribution across the CSR spectrum. (2) A significant correlation exists between CSR strategies and functional trait indicators. Specifically, the C strategy shows a significant positive correlation with chlorophyll content and tree height increment, and a significant negative correlation with leaf phosphorus content. The S strategy is significantly negatively correlated with tree height increment. The R strategy exhibits significant positive correlations with chlorophyll content and tree height increment, and significant negative correlations with leaf nitrogen content and leaf phosphorus content. (3) Flood time and depth are identified as key environmental factors driving the variation in CSR strategies within the young mangrove plantations. This study substantiates the applicability of CSR theory in intertidal artificial mangrove ecosystems, elucidating the mechanistic connections between plant adaptive strategies and ecological niche occupation. The results provide both theoretical insights and practical guidance for optimizing species selection and enhancing the efficiency of mangrove ecosystem restoration.
2026, 48(1): 30-41.
doi: 10.12284/hyxb2026004
Abstract:
Gross Oxygen production (GOP) in the surface ocean is a key indicator for evaluating the intensity of phytoplankton photosynthesis and the efficiency of marine biological carbon sequestration. However, photosynthesis and respiration occur simultaneously. It is very difficult to distinguish the total photosynthetic O2 production from respiration O2 consumption. Therefore, in situ measurement of marine GOP is extremely challenging. The triple oxygen isotope anomaly (17Δ) of dissolved oxygen does not change with respiration, providing a new isotopic indicator for evaluating marine GOP. Due to the extremely low natural abundance of 17O and its susceptibility to mass interference from N2, high precision measurement for triple oxygen isotopes (δ18O, 17Δ) of O2 is very difficult. In this study, we developed a high-vacuum pretreatment system and a gas chromatographic purification line. We successfully separated N2 from O2 and Ar for dissolved gases. By precisely controlling the temperature and collection time, we ensured 100% collection of O2 and avoided oxygen isotopic fractionation from purification. Based on this method, the observed long-term external precision of the air standard was ±2.6 per meg for 17Δ. Then, we analyzed the triple oxygen isotopic compositions of 5 dissolved gas samples collected in Prydz Bay, Southern Ocean, in January 2021. The mean 17Δ value of dissolved oxygen in the mixed layer was 66 per meg, corresponding to an average GOP of 181 mmol O2 m−2 day−1. Our observation is consistent with the relatively low GOP of the high-latitude Southern Ocean during summer. The high-precision analytical method for triple oxygen isotopes of O2 in this study demonstrates great potential for applications in marine GOP research and also provides valuable support for atmospheric and ice core trapped gas studies.
Gross Oxygen production (GOP) in the surface ocean is a key indicator for evaluating the intensity of phytoplankton photosynthesis and the efficiency of marine biological carbon sequestration. However, photosynthesis and respiration occur simultaneously. It is very difficult to distinguish the total photosynthetic O2 production from respiration O2 consumption. Therefore, in situ measurement of marine GOP is extremely challenging. The triple oxygen isotope anomaly (17Δ) of dissolved oxygen does not change with respiration, providing a new isotopic indicator for evaluating marine GOP. Due to the extremely low natural abundance of 17O and its susceptibility to mass interference from N2, high precision measurement for triple oxygen isotopes (δ18O, 17Δ) of O2 is very difficult. In this study, we developed a high-vacuum pretreatment system and a gas chromatographic purification line. We successfully separated N2 from O2 and Ar for dissolved gases. By precisely controlling the temperature and collection time, we ensured 100% collection of O2 and avoided oxygen isotopic fractionation from purification. Based on this method, the observed long-term external precision of the air standard was ±2.6 per meg for 17Δ. Then, we analyzed the triple oxygen isotopic compositions of 5 dissolved gas samples collected in Prydz Bay, Southern Ocean, in January 2021. The mean 17Δ value of dissolved oxygen in the mixed layer was 66 per meg, corresponding to an average GOP of 181 mmol O2 m−2 day−1. Our observation is consistent with the relatively low GOP of the high-latitude Southern Ocean during summer. The high-precision analytical method for triple oxygen isotopes of O2 in this study demonstrates great potential for applications in marine GOP research and also provides valuable support for atmospheric and ice core trapped gas studies.
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