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1.
Using the Ecopath with Ecosim software, a trophic structure model of the Beibu Gulf was constructed to explore the energy flows and provide a snapshot of the ecosystem operations. Input data were mainly from the trawl survey data collected from October 1998 to September 1999 and related literatures. The impacts of various fishing pressure on the biomass were examined by simulation at different fishing mortality rates. The model consists of 20 functional groups (boxes), each representing organisms with a similar role in the food web, and only covers the major trophic flows in the Beibu Gulf ecosystem. It was found that the food web of the Beibu Gulf was dominated by the primary producers path, and phytoplankton was the primary producer mostly used as a food source. The fractional trophic levels ranged from 1.0 to 4.02, and the marine mammals occupied the highest trophic level. Using network analysis, the ecosystem network was mapped into a linear food chain, and six discrete trophic levels were found with a mean transfer efficiency of 11.2%. The Finn cycling index was 9.73%. The path length was 1.821. The omnivory index was 0.197. The ecosystem had some degree of instability due to exploitation and other human activities, according to Odum’s theory of ecosystem development. A 10-year simulation was performed for each fishery scenario. The fishing mortality rate was found to have a strong impact on the biomass. By keeping the fishing mortality rate at the current level for all fishing sectors, scenario 1 had a drastic decrease in the large fish groups. The biomass of the small and medium pelagic fish would increase to some extent. The biomass of the small and low trophic level species, jellyfish, prawns and benthic crustaceans would be stable. The total biomass of the fishery resources would have a 10% decrease from the current biomass after 10 years. In contrast, the reduced fishing mortality rate induced the recovery of biomass (scenarios 2–4). In scenario 2, the biomass of the large demersal fish and the large pelagic fish would increase to over 16 times and 10 times, respectively, of their current level. In scenario 4, the biomass of the large pelagic fish would increase to over 3 times of its current level. The total biomass of the fish groups, especially the high trophic level groups, would become significantly higher after 10 years, which illustrates the contribution on biomass recovery by relaxing the fishing pressure. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Author contributions: Xiaoping Jia designed research; Zuozhi Chen and Yongsong Qiu performed research; Zuozhi Chen, Yongsong Qiu, and Shannan Xu analyzed data; and Zuozhi Chen and Shannan Xu wrote the article.  相似文献   

2.
北部湾带鱼的摄食习性   总被引:4,自引:0,他引:4  
2008年8月至2009年9月,对北部湾带鱼逐月渔获物胃含物进行鉴定和统计分析,研究其摄食习性.结果表明:北部湾带鱼捕食种类包括鱼类、头足类、底栖甲壳类以及浮游动物等,属于广食性动物.优势种类有少鳞犀鳕(37.99%)、蓝圆鲹(16.42%)和中国毛虾(10.03%).蓝圆鲹和尖吻小公鱼全年在全湾带鱼的食物中均有出现,是重要的饵料指标种类.摄食强度与饱满指数的季节差异十分显著(P<0.001),食物多样性无显著季节性差异(P>0.05),秋季最高,全年平均为1.97.聚类分析表明,北部湾带鱼在达到50%性成熟肛长值(190 mm)时,饵料由幼鱼的以小型浮游动物、中上层鱼类及甲壳类为主向成鱼的以较大型鱼类和头足类为主转换.  相似文献   

3.
2008年8月至2009年9月,对北部湾带鱼逐月渔获物胃含物进行鉴定和统计分析,研究其摄食习性.结果表明:北部湾带鱼捕食种类包括鱼类、头足类、底栖甲壳类以及浮游动物等,属于广食性动物.优势种类有少鳞犀鳕(37.99%)、蓝圆鲹(16.42%)和中国毛虾(10.03%).蓝圆鲹和尖吻小公鱼全年在全湾带鱼的食物中均有出现,是重要的饵料指标种类.摄食强度与饱满指数的季节差异十分显著(P<0.001),食物多样性无显著季节性差异(P>0.05),秋季最高,全年平均为1.97.聚类分析表明,北部湾带鱼在达到50%性成熟肛长值(190 mm)时,饵料由幼鱼的以小型浮游动物、中上层鱼类及甲壳类为主向成鱼的以较大型鱼类和头足类为主转换.  相似文献   

4.
Sixty‐nine fish species belonging to 41 genera from 29 families and seven orders were collected during 2006–2007 by otter trawl in Beibu Gulf, northern South China Sea, for analysis of their length‐weight relationships (WLRs). The analysis included 19 species for which no previous WLR estimates were available in FISHBASE.  相似文献   

5.
The length–weight relationships of four fish species: Lophiomus setigerus (Vahl, 1797), Uranoscopus oligolepis Bleeker, 1878, Cynoglossus oligolepis (Bleeker, 1855), and Cynoglossus arel (Bloch & Schneider, 1801) were determined. Specimens were collected from the Beibu Gulf in the South China Sea by using bottom trawl nets (mesh size 4.0 cm, at a towing speed about 3 knots) in the seasonal investigations from August 2010 to May 2011. The values of parameter b of these four species ranged from 2.982–3.489 and remained within the normal range of 2.5–3.5.  相似文献   

6.
记述了南海北部湾盆地涠西南凹陷涠洲油田流沙港组下部储油层所储原油中萃取出的孢子花粉化石28属58种及藻类化石2属3种。通过对比孢子花粉及藻类化石的油源,确定了含油区的油源岩;并根据各类孢型母体植物的古生态特征探讨了油源岩的形成环境。结果表明,中始新统至下渐新统流沙港组暗色泥质岩是北部湾盆地的主力油源岩,中上渐新统涠洲组暗色泥质岩也是该区的油源岩;该区油源岩形成于亚热带温暖潮湿气候下的湖泊沉积环境。  相似文献   

7.
The South China Sea is one of the largest marginal seas, with relatively frequent passage of eddies and featuring distinct spatial variation in the western tropical Pacific Ocean. Here, we report a phylogenetic study of bacterial community structures in surface seawater of the northern South China Sea (nSCS). Samples collected from 31 sites across large environmental gradients were used to construct clone libraries and yielded 2,443 sequences grouped into 170 OTUs. Phylogenetic analysis revealed 23 bacterial classes with major components α-, β- and γ-Proteobacteria, as well as Cyanobacteria. At class and genus taxon levels, community structure of coastal waters was distinctively different from that of deep-sea waters and displayed a higher diversity index. Redundancy analyses revealed that bacterial community structures displayed a significant correlation with the water depth of individual sampling sites. Members of α-Proteobacteria were the principal component contributing to the differences of the clone libraries. Furthermore, the bacterial communities exhibited heterogeneity within zones of upwelling and anticyclonic eddies. Our results suggested that surface bacterial communities in nSCS had two-level patterns of spatial distribution structured by ecological types (coastal VS. oceanic zones) and mesoscale physical processes, and also provided evidence for bacterial phylogenetic phyla shaped by ecological preferences.  相似文献   

8.
9.
Yan Y R  Chen J L  Lu H S  Hou G  Lai J Y 《农业工程》2012,32(1):18-25
The monthly and ontogenetic variations in diet of hairtail Trichiurus margarites Li (1992) [20] (Perciformes, Trichiuridae) were examined in the Beibu Gulf of the South China Sea from October 2008 to September 2009. Stomachs of 666 hairtail ranging in size from 121 mm to 561 mm pre-anal length (PL) were sampled monthly from commercial fish catches. Fish were the primary prey, with Decapterus maruadsi (Perciformes, Carangidae) averaging 23% by number, 34% by weight, and 49% by Index of Relative Importance (IRI). Other important prey in the diet included the small benthic fish, Bregmaceros rarisquamosus and Bregmaceros nectabanus (Gadiformes, Bregmaceroridae) and the decapod shrimp, Acetes chinensis, with IRI percentages of 8%, 4%, and 3%, respectively. Low rates of cannibalism and predation on 30 additional species of prey were observed. Trophic diversity (Brillouin Index, Hz) was moderate throughout the year. Mean feeding intensity (Repletion Index, RI) varied considerably by month and increased with the gonad maturity stages of hairtail; conversely, the proportion of empty stomachs decreased with maturity stages, from 60.9% empty at Stage I to 41.6% empty at Stage VI. Prey weight and numbers differed significantly among the 14 PL size classes and increased with body size. Cluster analysis of prey IRI values also indicated differences in the feeding habits of hairtail by size class. Understanding the monthly and ontogenetic changes in hairtail diet may assist in the development and improvement of marine ecosystem modeling for the Beibu Gulf, South China Sea.  相似文献   

10.
广西北部湾近岸生态系统风险评价   总被引:7,自引:0,他引:7  
Chen ZZ  Cai WG  Xu SN  Huang ZR  Qiu YS 《应用生态学报》2011,22(11):2977-2986
根据2009年9月广西北部湾近岸的海洋生态调查资料,利用地理信息系统的空间分析功能,从海水水质、营养水平、生物量和初级生产力水平、生物多样性和生态系统缓冲容量5个方面分析了秋季广西北部湾近岸海域环境现状,并进一步利用生态风险综合指数对广西北部湾海洋生态风险进行了评价.结果表明:2009年秋季,广西北部湾近岸海域生态环境质量较好,大部分生态系统风险指标等级均处于“中低”或“较低”水平,整体处于低风险状态.生态风险综合指数结果显示,广西北部湾海域生态风险分布具有明显的空间异质性,离岸水域生态系统的风险综合指数较低,越靠近港湾内,风险状态等级越高.  相似文献   

11.
北部湾秋季底层鱼类多样性和优势种数量的变动趋势   总被引:7,自引:0,他引:7  
根据1992年、2001年和2006年秋季在北部湾进行的底拖网调查数据,对该海域鱼类的种类组成、物种多样性、优势种及其数量的变动趋势进行分析。1992年共记录鱼类171种,隶属17目77科;2001年记录鱼类156种,隶属18目71科;2006年记录157种,隶属17目67科。3个年代记录的鱼类均以鲈形目的种类数最多,其中1992年为96种(占56.14%)、2001年90种(占57.69%)和2006年89种(占56.69%)。鱼类的Pielou均匀度指数(J')和Shannon-Wiener多样性指数(H')的变化趋势一致:以2001年最高,为0.72和3.64;其次为1992年,为0.64和3.27;2006年最低,分别为0.52和2.64。丰富度指数(D)呈逐年下降的趋势:为1992年的21.03,2001年的20.74和2006年的19.61。建立非线性回归模型对北部湾3个年代出现的6种共有优势种(发光鲷Acropoma japonicum、带鱼Trichiurus haumela、二长棘鲷Parargyrops edita、黄斑鲾Leiognathus bindus、竹荚鱼Trachurus japonicus和黄带绯鲤Upeneus sulphureus)的数量变化趋势进行分析。结果表明:北部湾鱼类中的经济价值较高的优势种逐渐被低值和小型的鱼类所替代,但繁殖力较强和寿命较短的鱼类变动较小。在6种共同优势种中,黄斑鲾和发光鲷的渔获率呈上升趋势;带鱼和黄带绯鲤的渔获率呈下降趋势;而二长棘鲷和竹荚鱼的渔获率基本保持不变。研究结果表明,北部湾鱼类的优势种更替明显,总体变化趋势是k选择种类(以红笛鲷和黑印真鲨等为代表)逐渐被r选择种类(发光鲷、鲾科和天竺鱼科等为代表)所替代,即寿命长、个体大和营养级高的鱼类数量减少,寿命短、个体小和营养级较低的种类增多。  相似文献   

12.
2007年10月南海北部浮游纤毛虫的丰度和生物量   总被引:3,自引:0,他引:3  
张翠霞  张武昌  肖天 《生态学报》2010,30(4):867-877
报道2007年10月南海北部海域(21°25.47′N 17°24.95′N,109°28.86′E 113°13.01′E)纤毛虫丰度和生物量的水平分布及砂壳纤毛虫的种丰富度。包括了13个断面的82个站位,Rosette采水器采水,水深低于15 m的站位采0,5 m和10 m;小于30 m站位,采0,10 m和底层;大于30 m的站位,采0,10,30 m和底层。纤毛虫丰度为0 5757 ind./L,平均(848±776)ind./L。无壳纤毛虫占绝对优势,其丰度占纤毛虫总丰度的比例平均为(91.9±9)%;纤毛虫生物量为0 12.09μg C/L,平均是(1.2±1.54)μg C/L,无壳纤毛虫的生物量平均为(0.94±1.27)μg C/L,占纤毛虫总生物量的78.6%。共发现砂壳纤毛虫16个属,49种,拟铃虫最多,具有一定的季节性。纤毛虫水体(40 m到表层)丰度为6.4×1069.1×107ind./m2,平均是(3.6×106±1.4×106)ind./m2;水体生物量3.6 195.8 mg C/m2,平均(48.1±33.7)mg C/m2。纤毛虫多分布于近岸浅水区(高温低盐,高Chl a),最大丰度要高于我国其他海区,不是Chl a最高的地方纤毛虫的丰度也最大,纤毛虫丰度最大时Chl a偏低。  相似文献   

13.
Threadfin porgy Evynnis cardinalis is both a dominant fish species and an important fishing target in bottom trawl fisheries in the Beibu Gulf, South China Sea. It was listed as endangered (EN) in a recent International Union for Conservation of Nature (IUCN) red list. Despite its economic importance and endangered status, limited research on its biological characteristics and spatial–temporal distribution has been undertaken this last decade, creating uncertainty in current conservation and management. We analyse this species' spatial distribution characteristics using data from four seasonal bottom trawl surveys in 2014–2015, and report average catch per unit effort to vary seasonally, from 49.1 to 594.5 ind h−1. Growth, mortality and sexual maturity are reported for four time periods based on data from bottom trawl fishery surveys over 1961–1962, 1998–1999, 2006, and 2014–2015. Length frequency distributions changed from bimodal to unimodal, and the female-to-male ratio increased. Mean body length and length at first maturity decreased, whereas the growth coefficient increased, indicating miniaturization, early sexual maturity and accelerated growth, respectively. We report sparid catch to have first exceeded maximum sustainable yield in 2001, and to have remained overfished from 2010 to 2015. Since the 1980s, low-trophic-level fishes such as E. cardinalis have replaced high-trophic-level fishes such as Crimson snapper Lutjanus erythropterus to become dominant species. As catches have increased substantially, these species have been faced with overfishing, driving the ecosystem into an unstable state.  相似文献   

14.
A novel aerobic, bacteriochlorophyll-containing bacteria strain JLT1202rT was isolated from Beibu Gulf in the South China Sea. Cells were gram-negative, non-motile, and short-ovoid to rod-shaped with two narrower poles. Strain JLT1202rT formed circular, opaque, wine-red colonies, and grew optimally at 3–4?% NaCl, pH 7.5–8.0 and 28–30?°C. The strain was catalase, oxidase, ONPG, gelatin, and Voges–Proskauer test positive. In vivo absorption spectrum of bacteriochlorophyll a presented two peaks at 800 and 877?nm. The predominant cellular fatty acid was C18:1 ω7c and significant amounts of C16:0, C18:0, C10:0 3-OH, C16:0 2-OH, and 11-methyl C18:1 ω7c were present. Strain JLT1202rT contained Q-10 as the major respiratory quinone and the genomic DNA G+C content was 76.3?mol%. Phylogenetic analysis based on 16S rRNA gene sequences of various species with validly published names showed that strain JLT1202rT fell within the genus Roseibacterium, family Rhodobacteraceae, sharing the highest similarity with Roseibacterium elongatum OCh 323T (97.9?% similarity), followed by Dinoroseobacter shibae DFL 12T (95.4?% similarity). The phylogenetic distance of pufM genes between strain JLT1202rT and R. elongatum OCh 323T was 9.4?%, suggesting that strain JLT1202rT was distinct from the only strain of the genus Roseibacterium. Based on the variabilities of phylogenetic and phenotypic characteristics, strain JLT1202rT stands for a novel species of the genus Roseibacterium and the name R. beibuensis sp. nov. is proposed with JLT1202rT as the type strain (=JCM 18015T?=?CGMCC 1.10994T).  相似文献   

15.
Abstract

To study the contamination of heavy metals in the aquaculture area of Beibu Gulf, the concentrations of seven metals in seawater were investigated. The results showed that significant seasonal and spatial distributions of heavy metals were observed in the four aquaculture areas. Generally, the heavy-metal concentrations in the Maowei Sea were higher than the other three aquaculture areas, which may be related to local industrialization and urbanization development. The concentrations of some metals were obviously higher in wet seasons than in dry seasons, which may be attributed to the seasonal river discharge, rainfall and seawater intrusion. Compared to other regions, some metal levels revealed relatively high contamination. Remarkably, the concentrations of Hg, Cu and Cd were much higher than concentrations found in the past 20?years in the seawater of the Guangxi Beibu Gulf, suggesting that there were increasing anthropogenic inputs of those metals in the aquaculture areas. The assessment of ecological risk index (ERI) indicated that the highest ERI value was found in the Maowei Sea, followed by Pearl Bay, Lianzhou Bay and Hongsha. Hg is the main ecological risk factor, and the heavy-metal contamination in the aquaculture areas must not be ignored.  相似文献   

16.
Measurements of denitrification, nitrification and nitrogen fixation rates were made alongside with measuring of chemical and physical properties in sublittoral sediments of the South China Sea near the coast of Vietnam. Studied sediments were suboxic (Eh was positive as a rule), had 0.18–1.5 % of organic carbon, 0.004–0.135 % of total nitrogen and 3-12 % of total iron. The numbers of denitrifying and nitrate-reducing bacteria were as high as millions and hundreds of millions cells per gram wet weight of sediment matter, respectively. The processes of nitrification and denitrification were not spearated spacely. The nitrification was measured in both superficial layer and in a 10-cm sediment column. There were indirect evidences suggesting possibility of anaerobic ammonium oxidation. Denitrification was detectable in the sediments from two sites of sampling; maximal value was 86.2 μmoles N m−2h−1. The denitrification potential determined at 1 mM nitrate decreased regularly from the upper to lower layers. Its values in the different sediments ranged from 134 to 532 μmoles N m−2h−1. Nitrogen fixation (from 4.8 to 86μmoles N m−2h−1) was close to that found in similar sediments in temperate waters in summer, and was not a significant source of nitrogen. It was comparable with diffusion of ammonium from sedimnts.  相似文献   

17.
热带亚热带水库浮游植物叶绿素a与磷分布的特征   总被引:25,自引:0,他引:25  
于丰水期和枯水期对广东省19个大中型水库的浮游植物叶绿素a和磷(P)进行采样和测定,分析了P和叶绿素a的分布特征及其相关性。结果表明P的浓度和叶绿素a含量较低的有流溪河、新丰江、公平和白盆珠水库;而枯、丰两期P的浓度和叶绿素a含量均较高的有契爷石、石岩、鹤地和大镜山水库;其余12个水库均属于季节性差异较明显的水库,在丰水期由入流带来较多的P,而枯水期则因入流相对较少,P的含量也较低。大部分水库在枯水期P限制现象比较严重,而丰水期则有所缓解。P限制程度的不同导致了丰水期和枯水期水库浮游植物种群组成和叶绿素含量的变化。丰水期的优势种类P半饱和浓度较高,在枯水期这些种类不再是优势种的组成部分。而一些P半饱和浓度较低的种类,在丰水期和枯水期都成为各个水库的优势种。通过相关性分析,正磷酸盐(PO43--P)与叶绿素的相关系数较高,总磷(TP)与叶绿素的相关系数则相对较低。从时间上来看,枯水期PO43--P与叶绿素的相关性高于丰水期;从空间上看,大坝处PO43--P与叶绿素的相关性高于入水口。  相似文献   

18.
浮游真菌在海洋食物网和生物地球化学循环中发挥着关键作用。【目的】为解析广西北部湾茅尾海不同季节浮游真菌群落结构及其关键环境影响因子,于2017年7月(夏季)、9月(秋季)、12月(冬季)和2018年3月(春季)期间在该海域设置7个站点,采集表层海水样品。【方法】利用内部转录间隔区(internal transcribed spacer, ITS)基因高通量测序技术,分析茅尾海浮游真菌群落结构与多样性。【结果】茅尾海海域浮游真菌隶属6个门、26个纲、71个目、167个科、282个属和374个种。主要浮游真菌类群为子囊菌门(Ascomycota, 82.14%)和担子菌门(Basidiomycota, 10.74%),共占浮游真菌总丰度的92.88%。茅尾海浮游真菌群落Shannon指数和Simpson指数在春季最高,Chao1指数和丰富度(richness)指数在冬季最高。主坐标分析(principal coordinates analysis, PCoA)和相似性分析(analysis of similarities, ANOSIM)结果显示,不同季节浮游真菌群落的β多样性具有极显著差异(R=0.591 2, P<0.001)。通过随机森林模型分析(random forest modeling analysis, RF),发现黄曲霉(Aspergillus flavus)、二色胶孔菌(Gloeoporus dichrous)、杂色曲霉(Aspergillus subversicolor)和微扁沃利雅炭皮菌(Whalleya microplaca)、翹鱗香菇(Lentinus squarrosulus)等20种海洋浮游真菌对环境变化敏感,可用于评估茅尾海富营养化状况。Spearman相关性分析表明,浮游真菌α多样性与海水pH、盐度和溶解氧(dissolved oxygen, DO)呈显著正相关关系(P<0.05),与温度、叶绿素-a (chlorophyll a, Chl-a)以及总有机碳(total organic carbon, TOC)呈显著负相关关系(P<0.05)。方差分解分析(variance partitioning analysis, VPA)发现营养因子是浮游真菌群落结构的主要驱动因子。【结论】本研究可为揭示北部湾海洋浮游真菌多样性提供理论参考,并为茅尾海生态环境监测与资源利用提供科学依据。  相似文献   

19.
Observations of ctenophore species were made in the Gulf ofTrieste between 2003 and 2006. We examined native ctenophorespecies with special attention to representatives of the ordersLobata and Beroida, and we recorded among them two non-nativectenophores: Mnemiopsis leidyi A. Agassiz 1865 and Beroe ovatasensu Mayer, 1912. The validity of the Mediterranean speciesBeroe ovata is discussed. We determined that among the nativespecies, it is not Beroe ovata but rather Beroe cucumis sensuMayer, 1912 that occurs in the Mediterranean Sea.  相似文献   

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