Big Bang nucleosynthesis(BBN)theory predicts the primordial abundances of the light elements^(2) H(referred to as deuterium,or D for short),^(3)He,^(4)He,and^(7) Li produced in the early universe.Among these,deuterium...Big Bang nucleosynthesis(BBN)theory predicts the primordial abundances of the light elements^(2) H(referred to as deuterium,or D for short),^(3)He,^(4)He,and^(7) Li produced in the early universe.Among these,deuterium,the first nuclide produced by BBN,is a key primordial material for subsequent reactions.To date,the uncertainty in predicted deuterium abundance(D/H)remains larger than the observational precision.In this study,the Monte Carlo simulation code PRIMAT was used to investigate the sensitivity of 11 important BBN reactions to deuterium abundance.We found that the reaction rate uncertainties of the four reactions d(d,n)^(3)He,d(d,p)t,d(p,γ)^(3)He,and p(n,γ)d had the largest influence on the calculated D/H uncertainty.Currently,the calculated D/H uncertainty cannot reach observational precision even with the recent LUNA precise d(p,γ)^(3) He rate.From the nuclear physics aspect,there is still room to largely reduce the reaction-rate uncertainties;hence,further measurements of the important reactions involved in BBN are still necessary.A photodisintegration experiment will be conducted at the Shanghai Laser Electron Gamma Source Facility to precisely study the deuterium production reaction of p(n,γ)d.展开更多
Molecular oxygen abundance is a key parameter in understanding the chemical network of the interstellar medium.We estimate the molecular oxygen column density and abundance for a sample of Galactic massive star format...Molecular oxygen abundance is a key parameter in understanding the chemical network of the interstellar medium.We estimate the molecular oxygen column density and abundance for a sample of Galactic massive star formation regions based on observations from the Submillimiter Wave Astronomy Satellite(SWAS)survey.We obtained an averaged O_(2)spectrum based on this sample using the(SWAS)survey data(O_(2),487.249 GHz,N=3-1,J=3-2).No emission or absorption feature is seen around the supposed central velocity with a total integration time of t_(total)=8.67×10^(3)hr and an rms noise per channel of 1.45 m K.Assuming a kinetic temperature T_(kin)=30 K,we derive the 3σupper limit of the O_(2)column density to be 3.3×10^(15)cm^(-2),close to the lowest values reported in Galactic massive star formation regions in previous studies.The corresponding O_(2)abundance upper limit is6.7×10^(-8),lower than all previous results based on SWAS observations and is close to the lowest reported value in massive star formation regions.On a galactic scale,our statistical results confirm a generally low O_(2)abundance for Galactic massive star formation regions.This abundance is also lower than results reported in extragalactic sources.展开更多
Nova outbursts are the results of thermonuclear runaways,which occur when sufficient material accretes on the surfaces of white dwarfs(WDs).Using the MESA code,we construct a detailed grid for carbon-oxygen and oxygen...Nova outbursts are the results of thermonuclear runaways,which occur when sufficient material accretes on the surfaces of white dwarfs(WDs).Using the MESA code,we construct a detailed grid for carbon-oxygen and oxygen-neon-magnesium novae.By employing population synthesis methods,we conduct a statistical analysis of the distribution of novae in the Milky Way.In our models,on average,a typical nova system may undergo about8000 eruptions and the Galactic nova rate is~130 yr^(-1).The C,N,and O elements in nova ejecta are strongly affected by the mixing degree between WD core and accreted material.Our results show that the average value of^(12)C/^(13)C in nova ejecta is about an order of magnitude lower than that on the surface of a red giant,that for^(16)O/^(17)O is about 5 times lower,and that for^(14)N/^(15)N is about 1.5 times lower.The annual yields of^(13)C,^(15)N,and^(17)O from nova ejection are larger than those from AGB stars.This indicates that compared to a red giant,nova eruptions are a more important source of the odd-numbered nuclear elements of^(13)C,^(15)N,and^(17)O in the Galactic interstellar medium.展开更多
Variations of picoplankton groups were investigated over a one-month period in Daya Bay and Sanya Bay,in the northern South China Sea.The two coastal regions exhibited different variation patterns in physicochemical p...Variations of picoplankton groups were investigated over a one-month period in Daya Bay and Sanya Bay,in the northern South China Sea.The two coastal regions exhibited different variation patterns in physicochemical parameters.Moreover,the diel variations of picoplankton groups were different between the two bays.The abundance of the picoplankton in Sanya Bay displayed a pronounced diel variation,while it was not significant in Daya Bay.In addition,some similar patterns of picoplankton abundance were discovered.In the two bays,virioplankton exhibited the smallest fluctuation range,whereas picocyanobacteria fluctuated most markedly.The fluctuation range of picoplankton groups was larger in spring tide than in neap tide,especially in Sanya Bay.Random forest model analysis demonstrated that the variation of picoplankton groups was attributed to physical and chemical factors in Sanya Bay and Daya Bay,respectively.Therefore,our findings suggest that virioplankton abundance can persist more stably in response to changing environmental conditions compared to bacterioplankton and picophytoplankton.展开更多
The abundance, distribution and diversity of epibenthic echinoderm were investigated at Dungonab Bay in the Red Sea coastal water of the Sudan. Four permanent line transects were chosen. Eight (30 × 2) square met...The abundance, distribution and diversity of epibenthic echinoderm were investigated at Dungonab Bay in the Red Sea coastal water of the Sudan. Four permanent line transects were chosen. Eight (30 × 2) square metre belt transects along each permanent line transect at 20 metre intervals were used to collect data. The data were subjected to univariate and multivariate analyses. Spatial variations of epibenthic echinoderm abundance were assessed with one-way analysis of variance. Hierarchical agglomerative clustering was used to identify and illustrate the similarities in echinoderm abundance between line transects and between belt transects. Indices of richness (d), diversity (H'), evenness (J') and dominance (C) were used to explain the diversity of epibenthic echinoderm species. The distribution pattern of each echinoderm species was determined in each permanent line transect. A total of 986 individuals were recorded within sixteen species of epibenthic echinoderms in the four line transects. Holothuriidae was the dominant family (5 species and 342 individuals). The most abundant echinoderms species was Pearsonothuria graeffei (77 individuals, about 7.81%). Abundances intra-transects and intra-families were insignificant (f = 1.67, p = 0.183, df = 3 and f = 3.24, p = 0.083, df = 9, respectively). The highest values of Shannon-Wiener diversity index (H'), Pielou evenness index (J'), Margalef species richness index (d), and Simpson Dominance index (C) were 2.738, 0.9875, 2.791 and 0.07159, respectively. The distribution patterns of all species in the study transects varied between clumped and uniform, with the exception of Asthenosoma varium of the Echinothuridae family, which had clumped distribution patterns in all transects. The study concluded that Dungonab Bay supports rich and diverse communities of epibenthic echinoderms.展开更多
Inland wetlands in Abu Dhabi Emirate are wintering and stopover sites for migratory birds of prey. We conducted long-term regular monitoring surveys in Al Wathba Wetland Reserve (AWWR) from January 1995 to December 20...Inland wetlands in Abu Dhabi Emirate are wintering and stopover sites for migratory birds of prey. We conducted long-term regular monitoring surveys in Al Wathba Wetland Reserve (AWWR) from January 1995 to December 2022. Both diurnal and occasionally nocturnal surveys were undertaken to record the migratory raptors and owls in the Wetland Reserve. During the study, a total of 1282 regular monitoring visits were undertaken and 27 species of diurnal raptors and owls representing five families and three orders were detected. These represent 57% of the total species of birds of prey recorded in the UAE. Overall, 63% of all the species that we observed were Accipitriformes followed by 26% Falconiformes and 11% Strigiformes. We found that changes in mean daily temperature have a positive effect on raptor species diversity and abundance in the Wetland Reserve. The species encounter rate was higher in low temperature as compared to high temperature and overall regression equation was statistically significant F (4, 1126) = 8.49), p = 0.00). However, the numbers of raptors did not vary significantly across the years (p = 0.51). Western Marsh-harrier (Circus aeruginosus) and Greater Spotted Eagle (Clanga clanga) were recorded to be the most abundant species in the wetland reserve followed by Common Kestrel (Falco tinnunculus). However, the encounter rate of globally threatened Greater Spotted Eagle was detected to have significantly decreased since 2016. Moreover, 63% of the species detected were uncommon and rarely recorded such as 1) Saker Falcon 2) Lanner Falcon 3) Long-eared Owl & Merlin, which were the rare records from the wetland reserve. Furthermore, 27 years of regular monitoring in the wetland have yielded diverse diurnal raptors and owl fauna (H) = 0.83, (E) = 1.43 (Shannon Diversity Index). The results demonstrate that long-term monitoring surveys in arid environments are essential to determine the trends in the raptor populations and to document rare and globally important species.展开更多
Globally, human activities have a significant impact on the diversity, abundance, and distribution of large mammals in Protected Areas (PAs). These disturbances increase human pressure on biodiversity and species habi...Globally, human activities have a significant impact on the diversity, abundance, and distribution of large mammals in Protected Areas (PAs). These disturbances increase human pressure on biodiversity and species habitats, highlighting the need for conservation. This study aimed to assess the abundance and distribution of large mammals in different habitat types within Nimule National Park (NNP) and understand the impacts of human activities on them. Data on the abundance and distribution of large mammals and their respective habitat types were collected through line transect surveys. Human activity signs were observed and recorded along the transect lines. To estimate the impacts of human activities on the diversity, abundance, and distribution of large mammal species, as well as to identify any significant differences between them and their habitat types, the study utilized the Kruskal Wallis test, Polynomial multiple regressions, and diversity indices. The findings from the Shannon-Weiner and Simpson indices indicated that large mammal species were more diverse inside the park (H’ = 1.136;D = 0.570) compared to the buffer zone (H’ = 0.413;D = 0.171), with 85% (443 out of 510 samples) recorded within Nimule National Park. The species abundance showed a semi-balanced status (0.58). The diversity results among different habitat types revealed that large mammals were more diverse and highly distributed in both open woodlands (244) and dense woodlands (192), while riverine vegetation had the lowest diversity (8). Statistical tests demonstrated a highly significant difference at a 99% confidence interval (p-value = 0.01) between habitat types and identified species of large mammals. Additionally, the results highlighted the high abundance of Uganda kob (274), baboons (141), and warthog (57) across most habitat types, accounting for at least 75% of their distribution. The most prevalent human activities observed were cattle footprints (27%) and cattle dung (14%). Human footprints and tree cutting combined accounted for 9%, indicating the practice of livestock grazing, poaching, encroachment, and fuelwood collection by local communities. However, these activities did not appear to significantly impact the diversity, abundance, and distribution of large mammals in Nimule National Park. Therefore, it is crucial to foster shared responsibilities and engage relevant stakeholders in the management and conservation of large wildlife species. Regular community awareness programs should be implemented to cultivate a sense of ownership. Moreover, it is recommended that a comprehensive survey be conducted on the population status of all mammal species in Nimule National Park, including its surrounding Buffer Zone. Monitoring the impact of human activities on their behavior and habitats using satellite images should also be carried out at least every five to ten years.展开更多
The present study conducted in the town of Ombessa aims to assess the influence of abiotic factors on the abundance dynamics and antibiotic susceptibility of Escherichia coli and Enterococcus faecalis isolated from so...The present study conducted in the town of Ombessa aims to assess the influence of abiotic factors on the abundance dynamics and antibiotic susceptibility of Escherichia coli and Enterococcus faecalis isolated from some aquatic systems from February to July 2022, monthly samples were taken at 10 water points used by the population (8 groundwater points and 2 surface water points). Samples were analyzed for physico-chemical parameters such as temperature, pH, electrical conductivity. Bacteriological variables such as BHAM, E. coli and E. faecalis abundances were also assessed. Antibiotic susceptibility of E. coli and E. faecalis was assessed using 06 antibiotics using the Kirby-Bauer diffusion disk method. The results show that bacterial abundances were the highest in surface waters. Bacterial densities were the highest in May and the lowest in February. The average densities recorded were 3845 CFU/100mL for BHAM, 380 CFU/100mL for E. coli and 14 CFU/100mL for E. faecalis in groundwater;and 8583 CFU/100mL for BHAM, 6878 CFU/100mL for E. coli and 812 CFU/100mL for E. faecalis in surface water. Antibiotic susceptibility tests showed that these bacterial species are sensitive to Gentamicin, Chloramphenicol, Azithromycin and Ciprofloxacin. They are all resistant to Trimethoprim/Sulfamethoxazole, E. coli is resistant to Doxycycline and E. faecalis has an intermediate sensitivity to Gentamicin. Overall, the Multiresistance to Antibiotics (MRA) indices obtained were above 0.2, indicating the presence of multidrug resistance in bacterial communities. The physico-chemical properties of the water varied over time and space, but on the whole remained below the threshold values of WHO guidelines. The degree of linkage between abiotic water variables and bacteriological parameters has shown that bacterial densities are more abundant in rainy seasons and increased O2 levels favor bacterial growth, while TSS, CO2 and dissolved nitrate levels affect the sensitivity of these bacterial species to antibiotics.展开更多
The fishing survey station located in the warm waters of the East China Sea is one of the abundant fishery resources of waters;with a large number of economic fish breeding grounds and economic juvenile feeding ground...The fishing survey station located in the warm waters of the East China Sea is one of the abundant fishery resources of waters;with a large number of economic fish breeding grounds and economic juvenile feeding grounds. Several fish species according to this bottom trawl survey results which appear in the annual survey from winter to autumn give us a total of 58 species, which have appeared throughout the year. But the vast majority of species appears only in certain seasons, according to the sea fish survey and based on seasonal migratory species or species mainly small endemic species. The survey of fish is tropical and subtropical warm water species and warm temperate species, and the history of the area has several types of 397 different species. There are many reasons, in addition to recent years, human disturbance and adverse consequences of environmental changes brought about, but also with the relevant sampling methods and sampler time, the survey sampled only trawl based, from Ping yang Ocean and Fisheries Bureau, the waters are still other jobs method net, gill nets, fishing industry, etc. Survey results show that the type of fish in the summer (58 species) > spring (55 species) > winter (51 species) > autumn (42 species). The type of season was among spring to summer rose, summer to autumn decline. The survey found that in the reef area of the Nanji Islands, no one species of fish is the dominant species throughout the year (according to the dominant species, each species is dominant only in one season). From the dominant species turnover accounting for the four seasons, in winter it has 53.72% of the total biomass or annual biomass, spring it has 41.53% of the overall biomass, summer it has 31.85% and autumn it has 38.56% of total biomass. Visible, seasonal succession of dominant species of fish phenomenon is very obvious, especially in the spring and winter, summer transfers dominate species at this stage show the greatest change, but winter, the transfer of this dominant species changes in minimal. Seasonal changes from biomass and the average annual marine fish survey biomass were 4832.25 g/h. From different seasons, the average biomass in winter (10779.88 g/h) > of the average biomass in spring (3624.1 g/hour) > of the mean biomass in autumn (3158 g/h) > the average Biomass in summer (1767 g/h). All of them show significant seasonal variation of the biomass, in winter and spring, the biomass is generally not high, but significantly higher than in the summer and autumn seasons. Each season, around the coast of southern Zhejiang, is less than the biomass and other catches off, which involves investigating sea location, size range, and the survey ship different network related tools. Another change from the area of biomass, some studies found that the survey of four-season fish of waters above the biological capacity of several kilograms only in some stations, namely stations and the highest biomass in summer appeared in stations 3, 7 and 11. In autumn the highest biomass appeared in stations 3, 6, 20 and 23.展开更多
To understand better the impact on mist net capture rates of the activity height of birds, light intensity, bird richness and abundance, we compared data from mist nets and point counts at the Jianfengling Forest Area...To understand better the impact on mist net capture rates of the activity height of birds, light intensity, bird richness and abundance, we compared data from mist nets and point counts at the Jianfengling Forest Area, Hainan Island. Mist-nets were operated for a total of 7135 net-hours. A total of 587 individuals of 45 bird species were captured. The total mean capture rate was 8.6 ± 10.4 per 100 net-hours. A total of 4932 individuals of 107 bird species were recorded by visual observation alone and 7616 individuals of 120 species were recorded in a visual and aural combination. The Grey-cheeked Fulvetta (Alcippe morrisonia) was the most abundant species, accounting for 38.7% of total captures, 27.9% of visual observations and 22.2% of visual + aural observations. The capture number was correlated with the number observed. Thirty-one species were more likely to be captured than observed. Canopy species, such as members of the Corvidae and Dicruridae, were seldom captured. For all ground feeding species, the capture number was greater than that of observation. Some cryptic species, such as the Lesser Wren Babbler (Napothera epilepidota), Spotnecked Babbler (Stachyris striolata) and Cuckoo Owl (Glaucidium cuculoides) also had a higher relative capture rate than that of observations. There was a significant relationship between light intensity and the number of birds captured.展开更多
With rapid urbanization occurring throughout China,the existence of Tree Sparrows (Passer montanus) in big cities is likely to be affected by a decrease in habitat and food availability.Can the urban Tree Sparrow adap...With rapid urbanization occurring throughout China,the existence of Tree Sparrows (Passer montanus) in big cities is likely to be affected by a decrease in habitat and food availability.Can the urban Tree Sparrow adapt to these changes? To elucidate this question,we studied the effect of urbanization on the abundance and distribution of Tree Sparrows in Beijing.We found the abundance of the Tree Sparrow negatively correlated with an urbanization score.Sparrow abundance was very low in residential areas with high-rise buildings,commercial centers and main roads,while their numbers were significantly higher in parks,university campuses,low building residential and suburban areas.Environmental factors within the 50 m and 200 m scales were most suitable in predicting the distribution of Tree Sparrows during winter,while factors within 50 m and 400 m scales are suitable during the breeding season.During winter,the number of conifer trees and pedestrians were the major factors at the 50 m scale,while the area of high-rise buildings and vegetation become the predominant factors on a 200 m scale.Alternatively,during the breeding season the area of low buildings and the number of conifers and pedestrians were the main factors on the 50 m scale while the area of high-rise buildings and vegetation remained the most important factors on the 400 m scale.These results indicate that highly urbanized areas are not suitable habitats for the Tree Sparrow,although this species can adapt to human environments.Food and nest sites for urban birds should be considered in urban planning of big cities in developing countries.展开更多
To understand the correlations between the abundance of Trichodina spp. and the water quality parameters, the abundance of Trichodina spp. on the gill of yellow catfish in aquaculture water was investigated. Meanwhile...To understand the correlations between the abundance of Trichodina spp. and the water quality parameters, the abundance of Trichodina spp. on the gill of yellow catfish in aquaculture water was investigated. Meanwhile, the temperature and total phosphorus, available phosphorus, total nitrogen, nitrite and ammonia nitro- gen contents of the aquaculture water were measured and determined. The results showed that the abundance of Trichodina spp. on the gill of yellow catfish was negatively correlated with the total phosphorus, available phosphorus and total nitro- gen contents in the aquaculture water, and was positively correlated with the nitrite content in the aquaculture water (P〈0.05); there were no significant correlations between the abundance of Trichodina spp. and the temperature and ammonia nitrogen content of the aquaculture water (P〉0.05).展开更多
为从系统整体角度完成对起落架收放系统的风险辨识和影响分析,将系统理论过程分析(Systematic Theory Process Analysis,STPA)与决策实验室分析-解释结构模型(Decision Making Trial and Evaluation Laboratory Interpretive Structural...为从系统整体角度完成对起落架收放系统的风险辨识和影响分析,将系统理论过程分析(Systematic Theory Process Analysis,STPA)与决策实验室分析-解释结构模型(Decision Making Trial and Evaluation Laboratory Interpretive Structural Modeling,DEMATEL-ISM)相结合来开展分析。首先,定义事故和系统级危险,以民机进近阶段放下起落架为例,运用STPA完成对风险因素的系统化辨识;其次,基于最大平均熵减(Maximum Mean De-entropy,MMDE)算法帮助DEMATEL-ISM模型确定阈值,完成对风险因素影响的重要性分析并识别可能引发系统级危险的风险传递路径,据此挖掘关键致因场景,以给出风险预防建议。结果显示:线路性能退化或失效、位置作动控制组件(Position Action Control Unit,PACU)核心处理器故障为关键原因因素,收放作动筒作动异常、机组成员操作不当、起落架指示灯显示异常、起落架液压选择阀作动异常、PACU信息接收有误为关键结果因素,这些因素均涉及多条可能引发系统级危险的风险传递路径,应予以重点控制。展开更多
基金supported by the National Key R&D Program of China(No.2022YFA1602401)by the National Natural Science Foundation of China(No.11825504)。
文摘Big Bang nucleosynthesis(BBN)theory predicts the primordial abundances of the light elements^(2) H(referred to as deuterium,or D for short),^(3)He,^(4)He,and^(7) Li produced in the early universe.Among these,deuterium,the first nuclide produced by BBN,is a key primordial material for subsequent reactions.To date,the uncertainty in predicted deuterium abundance(D/H)remains larger than the observational precision.In this study,the Monte Carlo simulation code PRIMAT was used to investigate the sensitivity of 11 important BBN reactions to deuterium abundance.We found that the reaction rate uncertainties of the four reactions d(d,n)^(3)He,d(d,p)t,d(p,γ)^(3)He,and p(n,γ)d had the largest influence on the calculated D/H uncertainty.Currently,the calculated D/H uncertainty cannot reach observational precision even with the recent LUNA precise d(p,γ)^(3) He rate.From the nuclear physics aspect,there is still room to largely reduce the reaction-rate uncertainties;hence,further measurements of the important reactions involved in BBN are still necessary.A photodisintegration experiment will be conducted at the Shanghai Laser Electron Gamma Source Facility to precisely study the deuterium production reaction of p(n,γ)d.
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.11988101 and12041302)the International Partnership Program of the Chinese Academy of Sciences(grant No.114A11KYSB20210010)+5 种基金National Key R&D Program of China No.2023YFA1608004operated by the California Institute of Technology under a contract with the National Aeronautics and Space Administration(80NM0018D0004)the support of the Tianchi Talent Program of Xinjiang Uygur Autonomous Regionthe Collaborative Research Center 1601(SFB 1601 sub-project A2)funded by the Deutsche Forschungsgemeinschaft—500700252support from the University of Cologne and its Global Faculty program。
文摘Molecular oxygen abundance is a key parameter in understanding the chemical network of the interstellar medium.We estimate the molecular oxygen column density and abundance for a sample of Galactic massive star formation regions based on observations from the Submillimiter Wave Astronomy Satellite(SWAS)survey.We obtained an averaged O_(2)spectrum based on this sample using the(SWAS)survey data(O_(2),487.249 GHz,N=3-1,J=3-2).No emission or absorption feature is seen around the supposed central velocity with a total integration time of t_(total)=8.67×10^(3)hr and an rms noise per channel of 1.45 m K.Assuming a kinetic temperature T_(kin)=30 K,we derive the 3σupper limit of the O_(2)column density to be 3.3×10^(15)cm^(-2),close to the lowest values reported in Galactic massive star formation regions in previous studies.The corresponding O_(2)abundance upper limit is6.7×10^(-8),lower than all previous results based on SWAS observations and is close to the lowest reported value in massive star formation regions.On a galactic scale,our statistical results confirm a generally low O_(2)abundance for Galactic massive star formation regions.This abundance is also lower than results reported in extragalactic sources.
文摘Nova outbursts are the results of thermonuclear runaways,which occur when sufficient material accretes on the surfaces of white dwarfs(WDs).Using the MESA code,we construct a detailed grid for carbon-oxygen and oxygen-neon-magnesium novae.By employing population synthesis methods,we conduct a statistical analysis of the distribution of novae in the Milky Way.In our models,on average,a typical nova system may undergo about8000 eruptions and the Galactic nova rate is~130 yr^(-1).The C,N,and O elements in nova ejecta are strongly affected by the mixing degree between WD core and accreted material.Our results show that the average value of^(12)C/^(13)C in nova ejecta is about an order of magnitude lower than that on the surface of a red giant,that for^(16)O/^(17)O is about 5 times lower,and that for^(14)N/^(15)N is about 1.5 times lower.The annual yields of^(13)C,^(15)N,and^(17)O from nova ejection are larger than those from AGB stars.This indicates that compared to a red giant,nova eruptions are a more important source of the odd-numbered nuclear elements of^(13)C,^(15)N,and^(17)O in the Galactic interstellar medium.
基金Supported by the National Natural Science Foundation of China(Nos.42176116,41576126,41890851,U21A6001)the Natural Science Foundation of Guangdong Province(No.2017A030306020)+4 种基金the Guangdong Major Project of Basic and Applied Basic Research(No.2019B030302004)the Rising Star Foundation of the South China Sea Institute of Oceanology(No.NHXX2019ST0101)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2018377)the Science and Technology Planning Project of Guangdong Province of China(No.2021B1212050023)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA19060503)。
文摘Variations of picoplankton groups were investigated over a one-month period in Daya Bay and Sanya Bay,in the northern South China Sea.The two coastal regions exhibited different variation patterns in physicochemical parameters.Moreover,the diel variations of picoplankton groups were different between the two bays.The abundance of the picoplankton in Sanya Bay displayed a pronounced diel variation,while it was not significant in Daya Bay.In addition,some similar patterns of picoplankton abundance were discovered.In the two bays,virioplankton exhibited the smallest fluctuation range,whereas picocyanobacteria fluctuated most markedly.The fluctuation range of picoplankton groups was larger in spring tide than in neap tide,especially in Sanya Bay.Random forest model analysis demonstrated that the variation of picoplankton groups was attributed to physical and chemical factors in Sanya Bay and Daya Bay,respectively.Therefore,our findings suggest that virioplankton abundance can persist more stably in response to changing environmental conditions compared to bacterioplankton and picophytoplankton.
文摘The abundance, distribution and diversity of epibenthic echinoderm were investigated at Dungonab Bay in the Red Sea coastal water of the Sudan. Four permanent line transects were chosen. Eight (30 × 2) square metre belt transects along each permanent line transect at 20 metre intervals were used to collect data. The data were subjected to univariate and multivariate analyses. Spatial variations of epibenthic echinoderm abundance were assessed with one-way analysis of variance. Hierarchical agglomerative clustering was used to identify and illustrate the similarities in echinoderm abundance between line transects and between belt transects. Indices of richness (d), diversity (H'), evenness (J') and dominance (C) were used to explain the diversity of epibenthic echinoderm species. The distribution pattern of each echinoderm species was determined in each permanent line transect. A total of 986 individuals were recorded within sixteen species of epibenthic echinoderms in the four line transects. Holothuriidae was the dominant family (5 species and 342 individuals). The most abundant echinoderms species was Pearsonothuria graeffei (77 individuals, about 7.81%). Abundances intra-transects and intra-families were insignificant (f = 1.67, p = 0.183, df = 3 and f = 3.24, p = 0.083, df = 9, respectively). The highest values of Shannon-Wiener diversity index (H'), Pielou evenness index (J'), Margalef species richness index (d), and Simpson Dominance index (C) were 2.738, 0.9875, 2.791 and 0.07159, respectively. The distribution patterns of all species in the study transects varied between clumped and uniform, with the exception of Asthenosoma varium of the Echinothuridae family, which had clumped distribution patterns in all transects. The study concluded that Dungonab Bay supports rich and diverse communities of epibenthic echinoderms.
文摘Inland wetlands in Abu Dhabi Emirate are wintering and stopover sites for migratory birds of prey. We conducted long-term regular monitoring surveys in Al Wathba Wetland Reserve (AWWR) from January 1995 to December 2022. Both diurnal and occasionally nocturnal surveys were undertaken to record the migratory raptors and owls in the Wetland Reserve. During the study, a total of 1282 regular monitoring visits were undertaken and 27 species of diurnal raptors and owls representing five families and three orders were detected. These represent 57% of the total species of birds of prey recorded in the UAE. Overall, 63% of all the species that we observed were Accipitriformes followed by 26% Falconiformes and 11% Strigiformes. We found that changes in mean daily temperature have a positive effect on raptor species diversity and abundance in the Wetland Reserve. The species encounter rate was higher in low temperature as compared to high temperature and overall regression equation was statistically significant F (4, 1126) = 8.49), p = 0.00). However, the numbers of raptors did not vary significantly across the years (p = 0.51). Western Marsh-harrier (Circus aeruginosus) and Greater Spotted Eagle (Clanga clanga) were recorded to be the most abundant species in the wetland reserve followed by Common Kestrel (Falco tinnunculus). However, the encounter rate of globally threatened Greater Spotted Eagle was detected to have significantly decreased since 2016. Moreover, 63% of the species detected were uncommon and rarely recorded such as 1) Saker Falcon 2) Lanner Falcon 3) Long-eared Owl & Merlin, which were the rare records from the wetland reserve. Furthermore, 27 years of regular monitoring in the wetland have yielded diverse diurnal raptors and owl fauna (H) = 0.83, (E) = 1.43 (Shannon Diversity Index). The results demonstrate that long-term monitoring surveys in arid environments are essential to determine the trends in the raptor populations and to document rare and globally important species.
文摘Globally, human activities have a significant impact on the diversity, abundance, and distribution of large mammals in Protected Areas (PAs). These disturbances increase human pressure on biodiversity and species habitats, highlighting the need for conservation. This study aimed to assess the abundance and distribution of large mammals in different habitat types within Nimule National Park (NNP) and understand the impacts of human activities on them. Data on the abundance and distribution of large mammals and their respective habitat types were collected through line transect surveys. Human activity signs were observed and recorded along the transect lines. To estimate the impacts of human activities on the diversity, abundance, and distribution of large mammal species, as well as to identify any significant differences between them and their habitat types, the study utilized the Kruskal Wallis test, Polynomial multiple regressions, and diversity indices. The findings from the Shannon-Weiner and Simpson indices indicated that large mammal species were more diverse inside the park (H’ = 1.136;D = 0.570) compared to the buffer zone (H’ = 0.413;D = 0.171), with 85% (443 out of 510 samples) recorded within Nimule National Park. The species abundance showed a semi-balanced status (0.58). The diversity results among different habitat types revealed that large mammals were more diverse and highly distributed in both open woodlands (244) and dense woodlands (192), while riverine vegetation had the lowest diversity (8). Statistical tests demonstrated a highly significant difference at a 99% confidence interval (p-value = 0.01) between habitat types and identified species of large mammals. Additionally, the results highlighted the high abundance of Uganda kob (274), baboons (141), and warthog (57) across most habitat types, accounting for at least 75% of their distribution. The most prevalent human activities observed were cattle footprints (27%) and cattle dung (14%). Human footprints and tree cutting combined accounted for 9%, indicating the practice of livestock grazing, poaching, encroachment, and fuelwood collection by local communities. However, these activities did not appear to significantly impact the diversity, abundance, and distribution of large mammals in Nimule National Park. Therefore, it is crucial to foster shared responsibilities and engage relevant stakeholders in the management and conservation of large wildlife species. Regular community awareness programs should be implemented to cultivate a sense of ownership. Moreover, it is recommended that a comprehensive survey be conducted on the population status of all mammal species in Nimule National Park, including its surrounding Buffer Zone. Monitoring the impact of human activities on their behavior and habitats using satellite images should also be carried out at least every five to ten years.
文摘The present study conducted in the town of Ombessa aims to assess the influence of abiotic factors on the abundance dynamics and antibiotic susceptibility of Escherichia coli and Enterococcus faecalis isolated from some aquatic systems from February to July 2022, monthly samples were taken at 10 water points used by the population (8 groundwater points and 2 surface water points). Samples were analyzed for physico-chemical parameters such as temperature, pH, electrical conductivity. Bacteriological variables such as BHAM, E. coli and E. faecalis abundances were also assessed. Antibiotic susceptibility of E. coli and E. faecalis was assessed using 06 antibiotics using the Kirby-Bauer diffusion disk method. The results show that bacterial abundances were the highest in surface waters. Bacterial densities were the highest in May and the lowest in February. The average densities recorded were 3845 CFU/100mL for BHAM, 380 CFU/100mL for E. coli and 14 CFU/100mL for E. faecalis in groundwater;and 8583 CFU/100mL for BHAM, 6878 CFU/100mL for E. coli and 812 CFU/100mL for E. faecalis in surface water. Antibiotic susceptibility tests showed that these bacterial species are sensitive to Gentamicin, Chloramphenicol, Azithromycin and Ciprofloxacin. They are all resistant to Trimethoprim/Sulfamethoxazole, E. coli is resistant to Doxycycline and E. faecalis has an intermediate sensitivity to Gentamicin. Overall, the Multiresistance to Antibiotics (MRA) indices obtained were above 0.2, indicating the presence of multidrug resistance in bacterial communities. The physico-chemical properties of the water varied over time and space, but on the whole remained below the threshold values of WHO guidelines. The degree of linkage between abiotic water variables and bacteriological parameters has shown that bacterial densities are more abundant in rainy seasons and increased O2 levels favor bacterial growth, while TSS, CO2 and dissolved nitrate levels affect the sensitivity of these bacterial species to antibiotics.
文摘The fishing survey station located in the warm waters of the East China Sea is one of the abundant fishery resources of waters;with a large number of economic fish breeding grounds and economic juvenile feeding grounds. Several fish species according to this bottom trawl survey results which appear in the annual survey from winter to autumn give us a total of 58 species, which have appeared throughout the year. But the vast majority of species appears only in certain seasons, according to the sea fish survey and based on seasonal migratory species or species mainly small endemic species. The survey of fish is tropical and subtropical warm water species and warm temperate species, and the history of the area has several types of 397 different species. There are many reasons, in addition to recent years, human disturbance and adverse consequences of environmental changes brought about, but also with the relevant sampling methods and sampler time, the survey sampled only trawl based, from Ping yang Ocean and Fisheries Bureau, the waters are still other jobs method net, gill nets, fishing industry, etc. Survey results show that the type of fish in the summer (58 species) > spring (55 species) > winter (51 species) > autumn (42 species). The type of season was among spring to summer rose, summer to autumn decline. The survey found that in the reef area of the Nanji Islands, no one species of fish is the dominant species throughout the year (according to the dominant species, each species is dominant only in one season). From the dominant species turnover accounting for the four seasons, in winter it has 53.72% of the total biomass or annual biomass, spring it has 41.53% of the overall biomass, summer it has 31.85% and autumn it has 38.56% of total biomass. Visible, seasonal succession of dominant species of fish phenomenon is very obvious, especially in the spring and winter, summer transfers dominate species at this stage show the greatest change, but winter, the transfer of this dominant species changes in minimal. Seasonal changes from biomass and the average annual marine fish survey biomass were 4832.25 g/h. From different seasons, the average biomass in winter (10779.88 g/h) > of the average biomass in spring (3624.1 g/hour) > of the mean biomass in autumn (3158 g/h) > the average Biomass in summer (1767 g/h). All of them show significant seasonal variation of the biomass, in winter and spring, the biomass is generally not high, but significantly higher than in the summer and autumn seasons. Each season, around the coast of southern Zhejiang, is less than the biomass and other catches off, which involves investigating sea location, size range, and the survey ship different network related tools. Another change from the area of biomass, some studies found that the survey of four-season fish of waters above the biological capacity of several kilograms only in some stations, namely stations and the highest biomass in summer appeared in stations 3, 7 and 11. In autumn the highest biomass appeared in stations 3, 6, 20 and 23.
基金funded by the Kadoorie Farm and Botanical Garden and the Hong Kong Special Administrative Region,China
文摘To understand better the impact on mist net capture rates of the activity height of birds, light intensity, bird richness and abundance, we compared data from mist nets and point counts at the Jianfengling Forest Area, Hainan Island. Mist-nets were operated for a total of 7135 net-hours. A total of 587 individuals of 45 bird species were captured. The total mean capture rate was 8.6 ± 10.4 per 100 net-hours. A total of 4932 individuals of 107 bird species were recorded by visual observation alone and 7616 individuals of 120 species were recorded in a visual and aural combination. The Grey-cheeked Fulvetta (Alcippe morrisonia) was the most abundant species, accounting for 38.7% of total captures, 27.9% of visual observations and 22.2% of visual + aural observations. The capture number was correlated with the number observed. Thirty-one species were more likely to be captured than observed. Canopy species, such as members of the Corvidae and Dicruridae, were seldom captured. For all ground feeding species, the capture number was greater than that of observation. Some cryptic species, such as the Lesser Wren Babbler (Napothera epilepidota), Spotnecked Babbler (Stachyris striolata) and Cuckoo Owl (Glaucidium cuculoides) also had a higher relative capture rate than that of observations. There was a significant relationship between light intensity and the number of birds captured.
基金supported by the National Natural Science Foundation of China (Grant No. 30900181)“111 Project” (2008-B08044)
文摘With rapid urbanization occurring throughout China,the existence of Tree Sparrows (Passer montanus) in big cities is likely to be affected by a decrease in habitat and food availability.Can the urban Tree Sparrow adapt to these changes? To elucidate this question,we studied the effect of urbanization on the abundance and distribution of Tree Sparrows in Beijing.We found the abundance of the Tree Sparrow negatively correlated with an urbanization score.Sparrow abundance was very low in residential areas with high-rise buildings,commercial centers and main roads,while their numbers were significantly higher in parks,university campuses,low building residential and suburban areas.Environmental factors within the 50 m and 200 m scales were most suitable in predicting the distribution of Tree Sparrows during winter,while factors within 50 m and 400 m scales are suitable during the breeding season.During winter,the number of conifer trees and pedestrians were the major factors at the 50 m scale,while the area of high-rise buildings and vegetation become the predominant factors on a 200 m scale.Alternatively,during the breeding season the area of low buildings and the number of conifers and pedestrians were the main factors on the 50 m scale while the area of high-rise buildings and vegetation remained the most important factors on the 400 m scale.These results indicate that highly urbanized areas are not suitable habitats for the Tree Sparrow,although this species can adapt to human environments.Food and nest sites for urban birds should be considered in urban planning of big cities in developing countries.
基金Supported by National Natural Science Foundation of China(31402343)Project of Wuhan Academy of Agricultural Science(Cxfzx201503)~~
文摘To understand the correlations between the abundance of Trichodina spp. and the water quality parameters, the abundance of Trichodina spp. on the gill of yellow catfish in aquaculture water was investigated. Meanwhile, the temperature and total phosphorus, available phosphorus, total nitrogen, nitrite and ammonia nitro- gen contents of the aquaculture water were measured and determined. The results showed that the abundance of Trichodina spp. on the gill of yellow catfish was negatively correlated with the total phosphorus, available phosphorus and total nitro- gen contents in the aquaculture water, and was positively correlated with the nitrite content in the aquaculture water (P〈0.05); there were no significant correlations between the abundance of Trichodina spp. and the temperature and ammonia nitrogen content of the aquaculture water (P〉0.05).
文摘为从系统整体角度完成对起落架收放系统的风险辨识和影响分析,将系统理论过程分析(Systematic Theory Process Analysis,STPA)与决策实验室分析-解释结构模型(Decision Making Trial and Evaluation Laboratory Interpretive Structural Modeling,DEMATEL-ISM)相结合来开展分析。首先,定义事故和系统级危险,以民机进近阶段放下起落架为例,运用STPA完成对风险因素的系统化辨识;其次,基于最大平均熵减(Maximum Mean De-entropy,MMDE)算法帮助DEMATEL-ISM模型确定阈值,完成对风险因素影响的重要性分析并识别可能引发系统级危险的风险传递路径,据此挖掘关键致因场景,以给出风险预防建议。结果显示:线路性能退化或失效、位置作动控制组件(Position Action Control Unit,PACU)核心处理器故障为关键原因因素,收放作动筒作动异常、机组成员操作不当、起落架指示灯显示异常、起落架液压选择阀作动异常、PACU信息接收有误为关键结果因素,这些因素均涉及多条可能引发系统级危险的风险传递路径,应予以重点控制。