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排序方式: 共有2219条查询结果,搜索用时 15 毫秒
951.
报道了2005年春季南海北部23个大面站网采浮游植物的调查结果,对浮游植物的群落结构进行了初步研究.共鉴定浮游植物3门73种,硅藻种类最多(50种),其次为甲藻(22种)和金藻(1种);浮游植物细胞丰度平均为3.07×104cells/m3,以硅藻为主(相对丰度平均93.8%),其次为甲藻(相对丰度平均6.16%)和金...  相似文献   
952.
2009年莱州湾近岸海域浮游植物群落的结构特征   总被引:3,自引:0,他引:3  
根据2009年5、8、10月莱州湾近岸海域的调查数据,对浮游植物的群落结构进行了初步研究.共鉴定浮游植物3门30属58种,主要为温带近岸性和广布性种.其中,硅藻门占总种教的87.9%,以角毛藻属(Chaetoceros)和圆筛藻属(Coscinodiscus)的种类最多;甲藻门占总种数的10.3%,以角藻属(Cerat...  相似文献   
953.
海南东寨港、三亚河和青梅港红树林群落健康评价   总被引:2,自引:0,他引:2  
以海南东寨港、三亚河和青梅港红树林保护区为研究对象,构建出红树林健康指数(EI)评价指标体系和方法,并确定了评价标准和评价等级,对海南红树林群落进行了健康状况评价.结果表明,2009年,东寨港、三亚河和青梅港保护区的红树林群落健康指数分别是0.8640,0.4798和0.5791,分别处于Ⅰ级(健康)、Ⅲ级(亚健康)和Ⅱ级(中等健康状态).结果说明东寨港红树林群落结构和功能稳定,生态演替序列完整,对环境压力响应良好.三亚河和青梅港红树林处于城市中心区和旅游开发区,受外界干扰影响大,退化明显,红树林的保护和恢复受到不同程度的限制.  相似文献   
954.
Ciliated protozoa play important roles in micro-ecosystems, especially in marine biotopes. However, few studies have been carried out on the periphytic, or aufwuch, forms in mariculture waters so far. In this study, we sampled periphytic ciliate communities in two closed mariculture ponds (ponds CP1 and CP2) and a natural seawater reservoir (pond RP) using a glass slide method to evaluate their colonizing processes and general ecological features, as well as their application as water quality indicators. We analyzed species compositions, structural parameters (species number, richness, diversity, evenness, abundance and dBP) and functional parameters (G, Seq and T90%). Pond RP was characterized by higher levels of structural parameters (except for abundance and dBP) and more equal proportion of the major taxonomic groups. The values of Seq were significantly higher in pond RP and similar in both pond CP1 and CP2. It was also demonstrated that environmental factors, including NO2-H, NO3-H, NH3-H, soluble reactive phosphate, temperature and pH, were the first principal factors affecting the communities. Among them, temperature and chemical factors were all significantly and negatively correlated with species number (P<0.01), richness (P<0.01), diversity (P<0.01), and positive correlated with abundance (P<0.01). Opposite correlations between pH and structural parameters were observed. This study showed that there were significant differences in species composition, structural parameters and functional parameters of the periphytic ciliate communities among the ponds, which were in agreement with the water quality. Results of this study confirmed the periphytic ciliate communities to be useful bioindicators of water quality in intensive mariculture waters.  相似文献   
955.
The abundance and behaviour of fish on and around coral reefs at Twin Mounds and Giant Mounds, carbonate mounds located on the continental shelf off Ireland (600-1100 m), were studied using two Remotely Operated Vehicle (ROV) dives. We recorded 30 fish taxa on the dives, together with three species of Scleractinia (Lophelia pertusa, Madrepora oculata and Desmophyllum cristagalli) and a diverse range of other corals (Antipatharia, Alcyonacea, and Stylasteridae). Stands of live coral provided the only habitat in which Guttigadus latifrons was observed whereas Neocyttus helgae was found predominantly on structural habitats provided by dead coral. Significantly more fish were found on structurally complex coral rubble habitats than on flatter areas where coral rubble was clogged with sand. The most common species recorded was Lepidion eques (2136 individuals), which always occurred a few cm above bottom and was significantly more active on the reefs than on sedimentary habitats. Synaphobranchus kaupii (1157 indiv.), N. helgae (198 indiv.) and Micromesistius poutassou (116 indiv.) were also common; S. kaupii did not exhibit habitat-related differences in behaviour, whilst N. helgae was more active over the reefs and other structured habitats whereas M. poutassou was more active with decreasing habitat complexity. Trawl damage and abandoned fishing gear was observed at both sites. We conclude that Irish coral reefs provide complex habitats that are home to a diverse assemblage of fish utilising the range of niches occurring both above and within the reef structure.  相似文献   
956.
西藏乌柳群落特征   总被引:2,自引:0,他引:2  
以一江两河流域为研究区,通过对西藏乌柳群落的典型地块设置11个标准地进行调查,分别从主要优势树种表现、物种组成、物种多样性、林分生长、地径结构、树高结构和树高-地径曲线等方面,分析了西藏乌柳群落的主要群落学和测树学特征。研究结构表明,1.西藏乌柳群落物种组成较为单一,群落中的物种数一般为1~4种,优势树种在群落中所占的比例较大,均大于85%;2.地径主要分布于5.0 cm以下,树高分布于1.0~5.0 m间,树高-地径服从二次曲线分布;3.由于群落物种组成较为单一,香农物种多样性指数均<1,SW和S、E的变化趋势大致相同,且与ED变化趋势相反。  相似文献   
957.
社区是农业文化遗产传承的载体,也是其保护的重要主体,社区参与对于农业文化遗产保护和可持续利用具有重要作用。本文以农业文化遗产地动态保护和适应性管理的主要方式——旅游为切人点,探讨农业文化遗产地旅游发展社区参与潜力及其空间分布特征。研究表明:(1)结构方程模型和“态度一行为”矩阵是科学评价农业文化遗产地旅游社区潜力的新方...  相似文献   
958.
李燕琴 《地理研究》2011,30(11):2030-2042
错综的矛盾常令以旅游业扶贫的乡村很快面临发展的瓶颈。以内蒙古边境村落室韦为例,以身处贫困漩涡中心的社区居民为研究对象,根据居民介入当地“家庭游”时间不同分为3组,通过深度访谈和问卷调查,剖析不同居民在旅游的经济、社会和文化影响感知方面的差异,从社区居民态度角度揭示出困扰当地旅游发展的三对主要矛盾,即负向的经济影响感知与...  相似文献   
959.
Middle and Late Cambrian trilobite faunas from the Dama section in western Hunanare are composed of 63 genera and subgenera, 84 species, and two forms of gen. et sp. indetermined. Which include a mixture of cosmopolitan agnostoids and polymeroids. Three new species, Hardyoides damaensis ,Meringaspis damaensis and Rhyssomelopus (Rodtrifinis ) nitidus, are described by present author in 2004. Besides, Erixanium is recognised for the first time in study area, which is significant for biostratigraphical correlation of the Late Cambrian in the Austalo-Asia region. According to distribution regularity vertical, the Middle and Late Cambrian trilobites can be divided into 9 trilobite communities for the Dama section. Based on the trilobite communities analysis, the author concludes that from the east Mt. Lailong to Dama through Fenghuang, further east, reach in Chenxi.the palaeoenvironments were changed from a shallow-water of oxygen-rich (platform margin slope) into a deep-water of oxygen-poor setting (basin).  相似文献   
960.
The composition and distribution of the benthic communities at the shelfbreak and upper slope of the Ubatuba region (south-eastern Brazil) were studied from a limited set of 15 dredge hauls taken between 130 and 600 m depth. Data analysis using multivariate methods showed the presence of three distinct benthic associations, related to depth and substratum. The first, between 130 and 180 m depth, was associated with the presence of large amounts of calcareous algal blocks, serving as a shelter for most of the organisms sampled, as well as an important substratum for sessile and filter-feeding animals. The second association was from the slope (240–350 m) comprising organisms exclusive to that area, and species common on shallower stations. The major faunal changes were observed in the third association at 500 m, which presented a fauna totally distinct from the former regions. It is suggested that this area is probably an upper limit for deep-living organisms in the region.  相似文献   
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