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排序方式: 共有192条查询结果,搜索用时 187 毫秒
1.
根据 2 0 0 1年 2月和 7月对崎岖列岛附近海域的水质和底质表层沉积物调查结果 ,采用环境质量单项评价标准指数法 ,对该海域环境质量现状进行了评价与分析。结果表明 :(1 )该海域水质的 p H值、溶解氧和石油类等环境因子基本符合一类海水水质标准 ,化学需氧量、活性磷酸盐和无机氮浓度则超标严重 ,该海域水质已处于严重富营养化状态 (夏季比冬季富营养化程度略低 ) ;(2 )该海域底质表层沉积物中除部分站位的重金属 Cu、 Zn含量超标外 ,有机质、石油类和重金属 Pb、 Cd、 Hg的含量均未超标 ,底质环境状况尚好 相似文献
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This paper brings together unpublished historical data sets and published literature to review the role of climatic, oceanographic and ecological processes in the marine ecosystem of the eastern Canadian Archipelago. Physical data include characteristics of the water masses, circulation patterns, sea ice conditions, and climatic records from 1950s onward. Biological data include unpublished data sets on nutrients, primary and secondary production, and sedimentation, which were collected during the 1980–1990s in the eastern Canadian Archipelago. These results show high year-to-year variability in nutrient inventories and ratios, the magnitude of the ice algae and phytoplankton bloom, the timing of ice algae sedimentation in the spring, and the composition of the zooplankton community. The significance of this high interannual variability and its effect on pelagic–benthic coupling processes is discussed in the context of climatic and oceanographic forcing, with emphasis on recent (past decade) Arctic changes. An estimate of total primary production in the Archipelago is also presented, along with published production estimates for other Arctic shelves, showing that the Archipelago may support up to 32% of the total primary production of Arctic shelves. The high year-to-year variability in production and carbon transfer pathways (e.g. pelagic versus benthic) in the Archipelago suggest that the system might be resilient to the increased variability in climatic conditions occurring in the past decade. However, this increased variability combined with directional change in climatic and oceanographic conditions might also modify the existing balance of ecological processes. For example, shifts in the timing of events appear to have already occurred in the past decade, with potential cascading effects throughout the ecosystem. 相似文献
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Abstract. The abundance, distribution, and species richness of the littoral sponges (0–55 m) from the Cabrera Archipelago (Balearic Islands) were studied along light gradients from the surface to the sea bottom and from cave mouths to their inner parts. A total of 98 species (11 Calcarea and 87 Demospongiae ) were recorded, 8 of which are new records for the Spanish coast.
Cluster and correspondence analyses enabled the identification of a sciophilous sponge group including three subgroups: sponges found only in semi-dark cave habitats, a subgroup common to the coralligenous, precoralligenous, and semi-dark cave biocoenoses, and a third subgroup exclusive to the coralligenous biocoenosis. A small number of photophilic species and other species having a wide bathymetric distribution made up another separate group. No species clusters for the different semi-sciophilous (either fleshy or carbonate) or photophilic seaweed communities were discernible. The number of sponge species was negatively correlated with the irradiance level. 相似文献
Cluster and correspondence analyses enabled the identification of a sciophilous sponge group including three subgroups: sponges found only in semi-dark cave habitats, a subgroup common to the coralligenous, precoralligenous, and semi-dark cave biocoenoses, and a third subgroup exclusive to the coralligenous biocoenosis. A small number of photophilic species and other species having a wide bathymetric distribution made up another separate group. No species clusters for the different semi-sciophilous (either fleshy or carbonate) or photophilic seaweed communities were discernible. The number of sponge species was negatively correlated with the irradiance level. 相似文献
5.
Statistical analysis of the magnetic fabric of samples from several successive lava flows emplaced under similar conditions can allow determination of the mean flow direction when magnetic fabric data from individual flows do not lead to reliable results. A difference between the obtained flow direction and the present dip direction indicates that the flows were tilted after emplacement. For 2 successive series of flows on the Jeanne d’Arc Peninsula presently NNW dipping, this method shows lava emplacement along a SSW–NNE direction. This indicates a gentle tilting acquired during a period of weak deformation in the whole archipelago. Additionally, the magnetic fabric data allow the reconstruction of the different conditions of emplacement of these two series of lava flows and of formation of the local thick conglomerate interbedded between these series. 相似文献
6.
舟山本岛北部灌门水道及邻近海域潮波特性初步研究 总被引:1,自引:0,他引:1
依据2004年在舟山灌门水道及邻近海域获取的同步潮位和潮流资料,对该海域的潮波特性进行了统计和分析,并对分析过程中发现的主要半日分潮经过灌门水道时振幅有较大幅度减小的现象进行了初步研究,认为截面积急剧变化的水道,潮波势能向动能的转换是产生主要半日分潮振幅减小的一个重要因素。这一结论或许有助于解释M2分潮波通过舟山群岛海域振幅明显减小的现象。 相似文献
7.
根据长山群岛 1965-2016 年渔业统计资料,分析长山群岛海域主要捕捞渔获物产量、平均营养级 (Mean trophic level, MTL)、渔业均衡指数 (Fishing in balance index,FiB) 年际变化,探讨其海洋渔业资源利用状况,并利用小波分析方法研究52年来渔获物 MTL 周期变化特征。研究表明: (1) 长山群岛捕捞产量、MTL 和 FiB 指数呈阶段性变化; (2) 长山群岛渔业资源开发经历初期开发、扩张捕捞、过度捕捞、资源破坏等四个阶段,渔业资源环境正在逐渐恶化;(3) 受人类捕捞活动影响,MTL 在 15~19 年和 24~34 年两种时间尺度下呈周期波动,30 年为第一主周期,17 年为第二主周期。长山群岛渔业资源破坏日益严重,未来几年平均营养级将呈下降趋势。为防止渔业资源进一步衰退,应加强捕捞活动管理力度,落实海洋渔业资源保护制度;完善预警机制,构建海洋渔业资源监测系统;同时应积极调整长山群岛渔业产业结构,提高资源产出效率. 相似文献
8.
2018?2019年舟山近海浮游动物群落结构春季年际变化及其与水团的关系 总被引:1,自引:1,他引:0
根据2018?2019年春季两个航次在舟山近海进行的浮游生物调查结果,对舟山近海的浮游动物群落结构(类群组成、优势种数量)年际变化进行了研究,利用典范对应分析(Canonical Correspondence Analysis, CCA)研究了两年春季浮游动物类群组成差异、优势种变化的原因,初步探讨了春季浮游动物群落结构动态变化的机制。结果表明:根据表层温度(Sea Surface Temperature,SST)、表层盐度(Sea Surface Salinity,SSS)的聚类分析,将该区域分为3个水团:杭州湾内水团(I区)、舟山本岛上升流水团II区)、舟山近海水团(III区)。不同水团对浮游动物类群组成影响显著,引起2018年和2019年春季3个水团区差异的主要贡献种(贡献率>10%)均为中华哲水蚤,同一水团两年间年际差异的贡献种如下:I区为捷氏歪水蚤(56.91%)和真刺唇角水蚤(12.34%);II区为中华哲水蚤(72.64%)、五角水母(13.35%);III区为中华哲水蚤(41.93%)、夜光虫(22.94%)。CCA分析表明,第1 CCA轴(CCA1)和第2 CCA轴(CCA2)共解释了两年春季浮游动物优势种累计方差的46.14%和物种?环境累计方差的97.82%。CCA1主要反映了空间(近海水团和湾内水团)的差异。CCA2主要反映了2018年和2019年站位的年际差异。盐度是影响春季浮游动物群落结构空间差异的主要因素,而温度、叶绿素a浓度是春季浮游动物群落结构年际差异的主要因素。 相似文献
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舟山潮间带生态学研究:Ⅱ.数量及其分布 总被引:3,自引:0,他引:3
舟山潮间带生物种类数量的平面分布与盐度和海岸开敞性有关,垂直分布与潮汐有关;群落数量的水平分布与底质和海岸开敞性有关,垂直分布与潮汐有关。舟山潮间带生物有明显的分带现象,隐蔽的岩岸区分为:滨螺带和藤壶-牡蛎带两个带;开敞性岩岸区分为:滨螺带,藤壶-(虫戚)-藻类带及藻类带3个带。沙滩区分为:沙蟹带和浅蛤-斧蛤带两个带;泥沙滩区分为:盐碱植物-滨螺带和招潮蟹-大眼蟹带;泥滩区分为:蟹守螺-囊螺带和蟹守螺-织纹螺带。 相似文献