Hydrobiologia最新文献_第4页

Effects of riparian forest and annual variation in stream environmental conditions on leaf litter breakdown and invertebrate communities in highland grassland streams 河岸林和溪流环境条件的年度变化对高原草原溪流落叶分解和无脊椎动物群落的影响

IF 2.6 3区生物学

Hydrobiologia Pub Date : 2024-08-13 DOI: 10.1007/s10750-024-05669-1

Emanuel Rampanelli Cararo, Renan de Souza Rezende

{"title":"Effects of riparian forest and annual variation in stream environmental conditions on leaf litter breakdown and invertebrate communities in highland grassland streams","authors":"Emanuel Rampanelli Cararo, Renan de Souza Rezende","doi":"10.1007/s10750-024-05669-1","DOIUrl":"https://doi.org/10.1007/s10750-024-05669-1","url":null,"abstract":"Leaf litter breakdown is a critical process in streams, as it plays a significant role in influencing food webs and biogeochemical cycles. Highland grasslands are often understudied landscapes, yet they are an excellent model system for evaluating how natural differences in riparian forest cover can influence litter breakdown in streams. We experimentally examined the effects of the presence and absence of riparian forest on temporal leaf litter breakdown and the associated biota in highland grassland streams. The 3-year experiment examined leaf litter breakdown in three stream reaches with riparian forest and three without. The results indicate that temperature could potentially mediate the temporal dynamics of leaf litter breakdown (mainly fine mesh) and the associated biota in highland grassland streams. No differences were found in leaf breakdown between stream reach types, but there was evidence of an increase in invertebrate density. Finally, leaf litter breakdown in the highland grasslands was more affected by annual variation than riparian forest presence, suggesting a context-dependent relationship.","PeriodicalId":13147,"journal":{"name":"Hydrobiologia","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142175791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Habitat structures and reproductive features suggesting a maintenance mechanism of reproductive isolation between ecomorphs of a herbivorous cichlid fish from Lake Tanganyika 栖息地结构和生殖特征表明坦噶尼喀湖一种草食性慈鲷异形之间的生殖隔离维持机制

IF 2.6 3区生物学

Hydrobiologia Pub Date : 2024-08-12 DOI: 10.1007/s10750-024-05654-8

Tetsumi Takahashi

{"title":"Habitat structures and reproductive features suggesting a maintenance mechanism of reproductive isolation between ecomorphs of a herbivorous cichlid fish from Lake Tanganyika","authors":"Tetsumi Takahashi","doi":"10.1007/s10750-024-05654-8","DOIUrl":"https://doi.org/10.1007/s10750-024-05654-8","url":null,"abstract":"Ecological speciation, driven by divergent selection across varying environments, is crucial for the evolution of biodiversity. To comprehend this phenomenon fully, investigating ongoing speciation events is imperative. Telmatochromis temporalis, a herbivorous cichlid endemic to Lake Tanganyika, recently revealed the existence of a slender morph inhabiting deep waters. Despite genetic similarity, it is reproductively isolated from the parapatric population of the normal morph inhabiting shallow waters. This study examined substrate features and life history traits to propose a mechanism that maintains the parapatric distribution, which likely contributes to reproductive isolation. The normal morph displayed a preference for natural shelters between rocks and invested significant energy on reproduction, likely well-adapted to shallow waters abundant in natural shelters and food resources. In contrast, the slender morph seemed to construct nests beneath rocks tailored to its body size and exhibited energy-saving reproduction, likely suited to deep waters with scarce natural shelters and food resources. These adaptive differences are likely responsible for parapatric distribution. Additionally, I discussed the potential for the slender morph and another morph, the dwarf morph, to have evolved in parallel from the normal morph through divergent natural selection, depending on the environmental challenges faced by the normal morph.","PeriodicalId":13147,"journal":{"name":"Hydrobiologia","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142175790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Temperature and depth drive population structure of the scaled sardine (Harengula sp.) in the western South Atlantic 温度和深度驱动南大西洋西部鳞沙丁鱼（Harengula sp.）的种群结构

IF 2.6 3区生物学

Hydrobiologia Pub Date : 2024-08-12 DOI: 10.1007/s10750-024-05662-8

Ana Beatriz Alves Bennemann, Jéssica Fernanda Ramos Coelho, Pedro Hollanda-Carvalho, Fabio Di Dario, João Luiz Gasparini, Ricardo Marques Dias, Liana de Figueiredo Mendes, Sergio Maia Queiroz Lima

{"title":"Temperature and depth drive population structure of the scaled sardine (Harengula sp.) in the western South Atlantic","authors":"Ana Beatriz Alves Bennemann, Jéssica Fernanda Ramos Coelho, Pedro Hollanda-Carvalho, Fabio Di Dario, João Luiz Gasparini, Ricardo Marques Dias, Liana de Figueiredo Mendes, Sergio Maia Queiroz Lima","doi":"10.1007/s10750-024-05662-8","DOIUrl":"https://doi.org/10.1007/s10750-024-05662-8","url":null,"abstract":"Understanding environmental features that impact population structure in marine systems is fundamental for sustainable fisheries management. In sardines and herrings, temperature is usually indicated as an important attribute in recruitment. Here, we investigate the hypothesis of additional structuring along the Brazilian coast in the scaled sardine Harengula sp. and possibility of using the highly variable mitochondrial control region as a molecular marker along continuous studies. We sequenced the mitochondrial control region of 152 individuals of Harengula sp. from 10 locations along the Brazilian coast and the archipelagoes of Fernando de Noronha (FNO, oceanic) and Abrolhos (ABR, continental) in the western South Atlantic. Analyses of molecular variance and haplotype network indicate that Harengula sp. is structured in three populations: one in FNO, isolated from the mainland by depth; and two in the Brazilian coast, mainly separated by temperature. Considering that FNO is a marine protected area and that sardines from this archipelago form a stock separated from the coast, their fisheries should be managed separately by participative cooperation among environmental agencies and local community. Additionally, it indicates that the mtDNA control region can be used in a long-term phylogeographic study of Harengula sp. as samples from other localities are obtained.","PeriodicalId":13147,"journal":{"name":"Hydrobiologia","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142175789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Recovery or reorganisation? Long-term increases in riverine taxonomic and functional diversity are confounded by compositional dynamics 恢复还是重组？河流分类学和功能多样性的长期增长受到组成动态的干扰

IF 2.2 3区生物学

Hydrobiologia Pub Date : 2024-08-10 DOI: 10.1007/s10750-024-05665-5

N. Baker, F. Pilotto, Ellen A. R. Welti, Diana Osadčaja, V. Palinauskas

引用次数: 0

Incorporating aquatic biodiversity into sustainability index for hydrographic sub-basins: a multi-criteria stakeholder assessment approach in the Upper Paraná River 将水生生物多样性纳入水文分流域可持续性指数：上巴拉那河利益相关者多标准评估方法

IF 2.6 3区生物学

Hydrobiologia Pub Date : 2024-08-07 DOI: 10.1007/s10750-024-05648-6

Leonardo da Silva Tomadon, Edivando Vitor do Couto, Dayani Bailly, Jóse Hilário Delconte Ferreira, Walter Timo de Vries, Angelo Antonio Agostinho

{"title":"Incorporating aquatic biodiversity into sustainability index for hydrographic sub-basins: a multi-criteria stakeholder assessment approach in the Upper Paraná River","authors":"Leonardo da Silva Tomadon, Edivando Vitor do Couto, Dayani Bailly, Jóse Hilário Delconte Ferreira, Walter Timo de Vries, Angelo Antonio Agostinho","doi":"10.1007/s10750-024-05648-6","DOIUrl":"https://doi.org/10.1007/s10750-024-05648-6","url":null,"abstract":"Sustainable development assessments in hydrographic sub-basins are powerful tools used to guide stakeholders. However, there remains a gap in incorporating new indicators (e.g., biodiversity indicators) into sustainability indexes, which have generally underestimated the environmental dimension. We propose an update to these indexes by incorporating biodiversity data on hydrographic sub-basins. Our goal was to introduce a new ecological sustainability index for hydrographic sub-basins (ESI-sb) that utilizes aquatic ecological indicators. We selected 16 indicators and aggregated them into four sustainability dimensions: economic, social, eco-environmental and negative environmental. We used a multi-criteria analysis based on the analysis hierarchy process (AHP) method to catch stakeholders' importance level of each indicator. The ESI-sb was calculated using the weighted average between the sub-indexes that represent the dimensions. Finally, we applied Gi* statistics to identify the ecological sustainability hotspots and coldspots regions, and the results showed in the Serra do Mar region, the southern region, and the Federal District had high ecological sustainability values; meanwhile, the hydrographic sub-basins that formed the coldspot clusters were located in the western region of the Upper Paraná River basin. The incorporation of aquatic biodiversity data into the index represents an innovation in sustainability indexes recently proposed to hydrographic sub-basins.<h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>","PeriodicalId":13147,"journal":{"name":"Hydrobiologia","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Stable isotope analysis reveals fish juveniles as a temporal main resource consumed by invasive pumpkinseed (Lepomis gibbosus) 稳定同位素分析表明，鱼类幼体是入侵南瓜籽（Lepomis gibbosus）消耗的时间性主要资源

IF 2.6 3区生物学

Hydrobiologia Pub Date : 2024-08-07 DOI: 10.1007/s10750-024-05658-4

Michal Hnilička, Michal Janáč, Eva Palupová, Maria Yu. Tkachenko, Petra Horká, Kateřina Jandová, Kateřina Holubová, Pavel Jurajda, Markéta Ondračková

{"title":"Stable isotope analysis reveals fish juveniles as a temporal main resource consumed by invasive pumpkinseed (Lepomis gibbosus)","authors":"Michal Hnilička, Michal Janáč, Eva Palupová, Maria Yu. Tkachenko, Petra Horká, Kateřina Jandová, Kateřina Holubová, Pavel Jurajda, Markéta Ondračková","doi":"10.1007/s10750-024-05658-4","DOIUrl":"https://doi.org/10.1007/s10750-024-05658-4","url":null,"abstract":"The pumpkinseed Lepomis gibbosus (Linnaeus, 1758) is a small centrarchid fish species from North America that has invaded most European basins, with pronounced expected impacts. Analyses of pumpkinseed diet in its invasive range using gut content analysis (GCA) show macrozoobenthos as the most common dietary item, suggesting a competitive effect on native fish communities. Our study uses a combination of GCA and stable isotope analysis (SIA) to document pumpkinseed diet at two sites in its invaded range and relates pumpkinseed diet preferences with parasitic load. SIA revealed juvenile fish as a major prey item at one of the sites (63 and 50% of the diet of small and the large fish), while GCA showed pumpkinseed preying mostly on macroinvertebrates (chironomids, gastropods, Ephemeroptera, and Zygoptera larvae) at both sites. While infrequent infection by trophically transmitted parasitic nematodes could be related to low consumption of zooplankton, substantial infection by metacercariae of Posthodiplostomum centrarchi Hoffman1958 appears to reflect relatively high consumption rates of its intermediate host, physid snails. Using SIA allowed to demonstrate that pumpkinseed feeding in its non-native range can be based on piscivory, emphasising the need for combining multiple methods when studying the impact of non-native species on food webs.","PeriodicalId":13147,"journal":{"name":"Hydrobiologia","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Variation of the sediment denitrifying bacterial community in a floodplain lake (Poyang Lake, China) during the wet, mid-dry and dry seasons 洪泛平原湖泊（中国鄱阳湖）沉积物反硝化细菌群落在雨季、中旱季和旱季的变化

IF 2.6 3区生物学

Hydrobiologia Pub Date : 2024-08-03 DOI: 10.1007/s10750-024-05666-4

Qiang Wu, Yiluo Zhong, Fei Wang, Yuwei Chen, Wenxiang Zou

{"title":"Variation of the sediment denitrifying bacterial community in a floodplain lake (Poyang Lake, China) during the wet, mid-dry and dry seasons","authors":"Qiang Wu, Yiluo Zhong, Fei Wang, Yuwei Chen, Wenxiang Zou","doi":"10.1007/s10750-024-05666-4","DOIUrl":"https://doi.org/10.1007/s10750-024-05666-4","url":null,"abstract":"To date, seasonal dynamics of the denitrifying bacterial community in floodplain lakes is unknown. Here, we investigated the alpha diversity, abundance and composition of the sediment nirS-type denitrifying bacteria in Poyang Lake during the wet, mid-dry and dry seasons using Illumina MiSeq sequencing and quantitative polymerase chain reaction assay. The results showed that only a small part of the total operational taxonomic units (OTUs) were shared by the three seasons. OTU richness, Chao richness estimator and Shannon index exhibited higher values in the wet season than in the dry season. Some regular patterns of variation in the composition of the nirS-type denitrifying community at three classification levels (phylum, class and genus) were found among seasons. Community structures of nirS-type denitrifying bacteria were significantly different across seasons. In addition, the abundance of nirS gene showed no seasonal pattern. Total nitrogen, total phosphorous and pH were the most significant factors elucidating the compositional variation of the nirS-type denitrifying community. This study provided a new evidence for the ecological effects of seasonal water level fluctuations and improved our understanding of the nitrogen removal processes in floodplain lakes.","PeriodicalId":13147,"journal":{"name":"Hydrobiologia","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Water conductivity mediates differences in clitellate assemblages in spring fens and adjacent streams 水传导性介导春季沼泽地和邻近溪流中甲壳类生物群落的差异

IF 2.6 3区生物学

Hydrobiologia Pub Date : 2024-08-02 DOI: 10.1007/s10750-024-05645-9

Bílková Martina, Schenková Jana, Horsák Michal

{"title":"Water conductivity mediates differences in clitellate assemblages in spring fens and adjacent streams","authors":"Bílková Martina, Schenková Jana, Horsák Michal","doi":"10.1007/s10750-024-05645-9","DOIUrl":"https://doi.org/10.1007/s10750-024-05645-9","url":null,"abstract":"Groundwater-fed helocrene springs constitute hydrologically heterogeneous environment, vulnerable to human and climate-induced changes. Using quantitative samples of clitellate assemblages, we investigated whether hydrologically stable nearby streams can serve as refugia for species inhabiting helocrenes, prone to seasonal desiccation. As water conductivity constitutes the main environmental gradient of helocrene springs, we categorized them as low or high-conductivity sites and compared their assemblage diversity. We hypothesized that the spring–stream association can change along this gradient, expecting assemblage homogenization is promoted by high tufa precipitation, creating differences with tufa-free nearby streams. Contrary to this prediction, the assemblages of low-conductivity helocrenes were more homogeneous, being also significantly different from those in the streams. This result is related to the apparently more favorable tufa-free substrate at low-conductivity fens, as shown by the high taxa richness and the number of indicator species. Contrary to the other invertebrates, the clitellates differed between spring fens and streams only under acidic conditions. It seems that small adjacent streams can only serve as potential refugia for spring fen biota at sites with high conductivity, while at sites with low conductivity, clitellate assemblages differ more from those in adjacent streams and thus are more susceptible to disturbance.","PeriodicalId":13147,"journal":{"name":"Hydrobiologia","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141881564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Visual pigment chromophore usage in Nicaraguan Midas cichlids: phenotypic plasticity and genetic assimilation of cyp27c1 expression 尼加拉瓜 Midas 慈鲷视觉色素发色团的使用：表型可塑性和 cyp27c1 表达的遗传同化

IF 2.6 3区生物学

Hydrobiologia Pub Date : 2024-08-02 DOI: 10.1007/s10750-024-05660-w

César Bertinetti, Axel Meyer, Julián Torres-Dowdall

{"title":"Visual pigment chromophore usage in Nicaraguan Midas cichlids: phenotypic plasticity and genetic assimilation of cyp27c1 expression","authors":"César Bertinetti, Axel Meyer, Julián Torres-Dowdall","doi":"10.1007/s10750-024-05660-w","DOIUrl":"https://doi.org/10.1007/s10750-024-05660-w","url":null,"abstract":"The wide-ranging photic conditions found across aquatic habitats may act as selective pressures that potentially drive the rapid evolution and diversity of the visual system in teleost fish. Teleost fish fine-tune their visual sensitivities by regulating the two components of visual pigments, the opsin protein and the chromophore. Compared with opsin protein variation, chromophore usage across photic habitats has received little attention. The Nicaraguan Midas cichlid species complex, Amphilophus cf citrinellus [Günther 1864], has independently colonized seven isolated crater lakes with different photic conditions, resulting in several recent adaptive radiations. Here, we investigate variation in cyp27c1, the main enzyme modulating chromophore exchange. We measured cyp27c1 expression in photic environments in the wild, its genetic component in laboratory-reared fish, and its response to different light conditions during development. We found that photic environments significantly predict variation in cyp27c1 expression in wild populations and that this variation seems to be genetically assimilated in two populations. Furthermore, light-induced cyp27c1 expression exhibited genotype-by-environment interactions in our manipulative experiments. Overall, within-lake variation in cyp27c1 expression was higher and inversely related to variation in opsin gene expression along the photic gradient, emphasizing the key role of cyp27c1 in the visual ecology of cichlid fish.","PeriodicalId":13147,"journal":{"name":"Hydrobiologia","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141881563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Invasive freshwater algae and cyanobacteria are overlooked: insights from a bibliometric study 被忽视的入侵淡水藻类和蓝藻：一项文献计量学研究的启示

IF 2.6 3区生物学

Hydrobiologia Pub Date : 2024-08-02 DOI: 10.1007/s10750-024-05655-7

Florencia S. Alvarez Dalinger, Claudia Nidia Borja, Camila Muñoz, Liliana Beatriz Moraña, Verónica Laura Lozano

{"title":"Invasive freshwater algae and cyanobacteria are overlooked: insights from a bibliometric study","authors":"Florencia S. Alvarez Dalinger, Claudia Nidia Borja, Camila Muñoz, Liliana Beatriz Moraña, Verónica Laura Lozano","doi":"10.1007/s10750-024-05655-7","DOIUrl":"https://doi.org/10.1007/s10750-024-05655-7","url":null,"abstract":"Biological invasions represent a critical global challenge, profoundly impacting ecosystems and driving environmental change. While the distribution of invasive animal or plant species has received considerable attention, our understanding of the global prevalence of invasive algae and cyanobacteria in continental freshwater ecosystems remains limited. With the aim of studying how much freshwater algae and cyanobacteria are being detected as invaders, we conducted a comprehensive bibliometric analysis. It revealed 72 reported species as invasive, with R. raciborskii, D. geminata, and C. furcoides emerging as principal ones. Only 52% of the reports quantified or analyzed environmental impacts. Among the documented impacts and environmental alterations, changes in phytoplankton structure and diversity were the most frequently reported, followed by toxin production, particularly associated with invasive cyanobacteria species. Geographically, there is a noticeable concentration of reports, with Africa and Asia being underrepresented. Meanwhile, the Czech Republic and Poland emerge as leaders in the number of species classified as invaders. This geographical bias suggests a significant gap in our understanding of the true distribution of invasive freshwater algae and cyanobacteria species.","PeriodicalId":13147,"journal":{"name":"Hydrobiologia","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141881565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0