东海区小黄鱼渔业生物学现状的分析   总被引：15，自引：1，他引：15  

林龙山  程家骅 《中国海洋大学学报(自然科学版)》2004,34(4):565-570

以2001年东海区渔业资源监测调查资料为依据，对小黄鱼的体长、体重、生长、死亡等渔业生物学特征及临界年龄等进行了分析研究。结果表明，目前东海区小黄鱼优势体长组为110～130mm，占41．34％；优势体重组为20～40g，占50．91％；总死亡系数为2．05，自然死亡系数为0．58，捕捞死亡系数为1．47，临界年龄为2．18龄。对照东海区小黄鱼生物学特征的历史状况分析，目前东海区小黄鱼个体小型化、低龄化、性成熟提早现象明显，生物学参数发生较大变化。建议在东海区现行资源状态下，小黄鱼的可捕标准应充分考虑其生物学现状加以科学调整。  相似文献   

胶州湾女姑山水域夏季赤潮高发期浮游植物群落结构特征   总被引：7，自引：0，他引：7  

张利永  刘东艳  孙军  邹景忠 《中国海洋大学学报(自然科学版)》2004,34(6):997-1002

根据 1998年 5～ 8月夏季赤潮高发期间 ,胶州湾女姑山水域浮游植物群落结构的种群组成特征和演替变化对赤潮的发生和种群变动特点进行初步研究。结果表明 ,夏季女姑山水域的浮游植物主要由硅、甲藻组成 ,硅藻在细胞和物种丰度上都占优势。浮游植物优势种在调查期间出现明显的演替现象 ,水温的升高和营养条件的变化是引起物种演替的主要原因。浮游植物细胞丰度在夏季呈明显的增长趋势 ,从 5月份 6.3× 10 5个cell/m3 增至 8月份的 6.7× 10 6个cell/m3 ;其中 ,由于赤潮的爆发 ,细胞丰度的最高峰出现在 7月份 ,为 1.5× 10 7个 /m3 。在赤潮爆发期间 ,赤潮原因种高齿状藻和中肋骨条藻发生了明显的演替现象 ,不同细胞大小的优势种和营养条件的变化是发生物种演替的主要原因。叶绿素a的浓度和细胞丰度的变化共同反映了赤潮发生的全部过程。  相似文献   

四川省旅游景区空间分布差异研究     

白军利  张辉  王香玉 《地理信息世界》2015,(1)

以四川省为研究区域,利用数理统计方法及GIS技术,采用资源丰裕度指数、变异系数、均衡度指数及均衡比系数,对A级旅游景区空间分布差异进行测度。结果表明：整体层面,旅游景区空间分布均衡程度由大到小依次是5A级景区、4A级景区、3A级景区、所有景区、2A级景区;市际层面,各州市旅游景区空间分布差异较大,旅游景区分布最多、丰裕度最高的是成都;四类均衡比系数显示,交通均衡比系数较小,其次是经济均衡比,表明交通和经济因素对四川省旅游景区空间分布影响最大,经济越发达,交通越通达,旅游景区空间分布越均衡;在此差异测算基础上,提出四川省旅游景区空间布局优化建议。  相似文献   

Abundance and distribution of ichthyoplankton in the upwelling zone off Oregon during anomalous El Niño conditions     

Richard D. Brodeur  Dena M. Gadomski  William G. Pearcy  Harold P. Batchelder  Charles B. Miller 《Estuarine, Coastal and Shelf Science》1985,21(3):365-378

The abundance and distribution patterns of nearshore ichthyoplankton were investigated during a year of anomalously high sea temperatures off Oregon. Samples collected from 2 to 18 km offshore from April through September of 1983 showed increased occurrences and higher abundances of taxa usually found at distances offshore of 37 km in other years. The dominant species collected, comprising more than half of the total larval fish abundance, was the northern anchovy (Engraulis mordax). Larval anchovy have rarely been collected inshore in previous studies. Many of the dominant taxa normally found inshore, especially osmerids, were present in reduced numbers in 1983. Changes in the hydrographic conditions associated with onshore surface drift and reduced summer upwelling during the 1983 El Niño could explain the distributional patterns observed. The warm inshore waters apparently provided a substantial spatial and temporal expansion of the spawning habitat for E. mordax.  相似文献   

Structural aspects of the surf-zone fish assemblage at King's Beach,Algoa Bay,South Africa: Short-term fluctuations     

Theresa Lasiak 《Estuarine, Coastal and Shelf Science》1984,18(3):347-360

Short-term changes in the King's Beach surf-zone fish assemblage were investigated by means of two 24 h studies (January and August 1979), and by seine netting on three consecutive days at both high and low tide. They revealed considerable variation in the fish assemblage over a 24 h period. Four species: the gorrie, Pomadasys olivaceum; the mullet, Liza richardsoni; the streepie, Sarpa salpa; and the sand steenbras, Lithognathus mormyrus, dominated the catches of both 24 h studies. The number of species caught reached a peak just after twilight. Trends in other community parameters were not consistent for these two sets of data. Considerable variation in dominant species, numbers and species diversity indices was observed from day to as well as between high and low tide. Shortterm fluctuations in various community parameters often exceeded the long-term variability observed in a seasonal study of this fish assemblage.  相似文献   

Structural aspects of the surf-zone fish assemblage at King's Beach,Algoa Bay,South Africa: Long-term fluctuations     

Theresa A. Lasiak 《Estuarine, Coastal and Shelf Science》1984,18(4):459-483

Regular collections of fish were obtained from the surf-zone at King's Beach, Algoa Bay. A total of 3970 fish, representing 50 species was caught with a coarse net and 16 857 fish, representing 37 species, were caught with a fine net. Predominant species were the blacktail, Diplodus sargus; the sand steenbras, Lithognathus mormyrus; the mullet, Liza richardsoni; the gorrie, Pomadasys olivaceum; the white stumpnose, Rhabdosargus globiceps; the sandshark, Rhinobatos annulatus; and the streepie, Sarpa salpa. No seasonal trends were discernible in the overall abundance or species diversity. The species composition of the dominant component of the fish assemblage varied considerably. This indicated instability in the community structure and cast doubts on the applicability of a classic community concept and the use of diversity indices. Neither classification nor correspondence analysis were of any use in identifying a characteristic species component. Multiple regression analysis indicated that short-term variations in wind conditions might be a primary determinant of fluctuations in abundance. The lack of seasonality in the community parameters may reflect the fact that short-term variability masks seasonal perturbations.  相似文献   

皖南国际文化旅游示范区文化资源丰度评价   总被引：3，自引：1，他引：2  

程晓丽  史杜芳 《地理科学》2017,37(5):766-772

以皖南国际文化旅游示范区为研究对象,从文化与旅游融合发展的视角,通过构建区域文化资源丰度评价指标体系,对示范区各地市文化资源丰度进行测度,得出如下结论：皖南国际文化旅游示范区中黄山、安庆、宣城、池州4市的文化资源赋存丰度为优级;马鞍山、芜湖市为良好;铜陵市为差级,优级区主要集中在南部和东西部,南北差异明显。从文化资源组合状况来看,黄山市文化资源组合状况最好,品牌资源众多,开发潜力巨大;其次是宣城、安庆和池州3市,资源类型齐全,组合状态较好;马鞍山、铜陵和芜湖3市较差,类型相对单一,开发难度较大。建议政府部门及旅游业界据此结果,科学评估文化资源的价值和开发方向,探索旅游开发的有效模式,推动文化与旅游融合发展,实现示范区优秀文化传承与创新。  相似文献   

广西金牙金矿床中饱和烃丰度分布特征及其意义   总被引：2，自引：0，他引：2       下载免费PDF全文

肖建新  张爱云 《地球科学》1997,22(2):177-180

对广西金牙金矿床的可溶有机质族组成和气相色谱分析表明，矿体饱和烃的丰度低于围岩，矿体与围岩总抽提物所气相色谱图亦明显不同，尤其是甲醇－丙酮－苯抽提物的区别更明显，矿体与围岩饱和烃丰度的差异为分析有机质在金矿形成过程中的作用提供了线索，对其意义进行了讨论。  相似文献   

The effect of rainfall and habitat on abundance and diversity of birds in a fenced protected area in the central Saudi Arabian desert     

Stephen F Newton  Anne V Newton 《Journal of Arid Environments》1997,35(4):715-735

Factors influencing avian abundance and diversity in central Saudi Arabia were investigated over a 28-month period using walked belt transects in five local habitat types in a 2200 km²fenced desert protected area established in 1989. Enclosure of the protected area has resulted in the development of a mosaic of densely vegetated grassland and savanna areas amongst the sand and gravel plains which dominate the surrounding landscape. Overall bird diversity showed biannual peaks corresponding to spring and autumn passage migration, when 30–40 species were recorded; troughs occurred in summer or winter (9–12 species) following poor spring or autumn rains. Bird numbers responded dramatically to heavy rainfall (> 20 mm in a month) occurring two months earlier, with major peaks recorded in autumn 1992 and May–June 1994. Numbers of granivorous species, principally larks, fluctuated mostly in relation to rainfall, whereas largely insectivorous species tended to remain more stable. A desert locust plague in spring/summer 1993, combined with poor spring rains, resulted in the lowest numbers and species diversity recorded during the study.  相似文献   

大兴安岭北部中生代花岗岩类地球化学特征及地质意义     

刘希瑶  王德力  刘驰 《地质与资源》1992,29(3):207

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