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全球气候变暖引起的热压力增大是南海诸岛珊瑚礁面临的最主要威胁,基于热压力对珊瑚礁白化的评估有利于对其保护和管理。周热度（Degree Heating Week , DHW）可以衡量热压力的强度和持续时间,代表过去连续12周珊瑚礁区海表温度（SST）正异常的累积。本文基于美国国家海洋和大气管理珊瑚礁监测计划（National Oceanic and Atmospheric Administration-Coral Reef Watch, NOAA-CRW）海表温度数据集,逐像元对35个年最大周热度数值进行K-means聚类分析,将南海诸岛珊瑚礁区分为6个区域:南沙–1、南沙–2、南沙–3、东沙、西沙和中沙珊瑚礁区。分析南海诸岛珊瑚礁区1985–2019年热压力时空变化及其与El Ni?o的相关关系。结果表明:（1）南海诸岛珊瑚礁区最大DHW为0～12.9℃?周,纬度上由高到低呈现减小变化规律。（2）线性拟合法分析1985–2019年的年最大DHW,显示南海诸岛珊瑚礁区热压力强度呈现上升趋势,为0.013～0.174℃?周/a,南海诸岛珊瑚礁区最大DHW出现在1998年、2010年、2014年。（3）年最大DHW可能造成93.9%的珊瑚礁发生超过一次白化的风险,19.6%的珊瑚礁发生超过一次死亡的风险。（4）南海诸岛珊瑚礁区的月均DHW和ONI交叉小波分析显示两者存在多时段8～32个月共振周期的时频特征和时滞相关性,证实南海诸岛珊瑚礁热压力随着厄尔尼诺事件发生而显著增大;时滞相关分析表明,ONI与南海诸岛珊瑚礁区热压力呈正相关关系,后者滞后于前者7～9个月的时间。 相似文献
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本文重点讨论热带海岛环境下混凝土在腐蚀介质中的腐蚀机理，探讨腐蚀与材料之间的关系。应用数理统计方法，得出混凝土在腐蚀前后各项参数变化的相关关系。利用扫描电子显微镜对混凝土试样作显微观察分析，从微观上掌握混凝土腐蚀的机理并提出一些反腐蚀方法和措施。试图证明使用抗硫酸盐水泥、珊瑚礁砂屑、海水拌制混凝土在海岛工程建设中有较大社会效益和经济效益。以上结果具有一定的实用和科学意义 相似文献
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本文根据实地考察并结合有关资料,对夏威夷群岛地貌的一些特点进行探讨。首先,分析了这些岛群的大地地貌特征;其次,介绍了灾害性地质地貌现象的控制和利用;最后,对夏威夷群岛的地貌演变趋势进行了探讨。这对大地地貌的研究以及对我国海岛开发将有所借鉴。 相似文献
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A.J.F. Hoitink 《Marine Geology》2004,208(1):13-31
The Bay of Banten, West Java, Indonesia represents a shallow coastal embayment harboring coral reefs subject to extremely turbid conditions. The sedimentary regime and flow structure of two contrasting coral reef islands in the embayment were investigated to identify the mechanisms responsible for mean and peak levels of suspended sediment concentration (SSC) around the reefs. Arrays of in situ calibrated optical backscatter (OBS) sensors were deployed across the reef slopes. Far field conditions were simultaneously monitored using an acoustic Doppler current profiler (ADCP) and a conductivity temperature and depth (CTD) probe, equipped with an OBS sensor. In addition, hydrographic surveys were conducted using the ADCP attached to a small fishing boat, navigating transects perpendicular to the reef islands. The direct influence of river plumes was found to be insignificant. Waves act only in the uppermost few meters of the reef slopes, where coral growth is most abundant and little sediment is available for resuspension. Tidal currents are the primary cause of high turbidity, which was inferred from peaks in the diurnal and semidiurnal frequency bands of SSC spectra, and the large depths where the turbidity variation sometimes initiates. The entrained sediment disperses upward across the reef slopes, which is likely due to a secondary current associated with bending of the flow along the curved, hydraulically rough reef slopes, in weakly stratified ambient waters. Changes in sediment availability, variable critical shear stresses for erosion and deposition, and the formation and evanescence of island wakes may explain the high variability of SSC at the reef slopes. 相似文献
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南海珊瑚岛礁远离大陆且面积较小,高分辨率遥感技术已成为大范围进行珊瑚岛礁监测的重要手段,而建立适用的遥感分类体系和解译标志是进行珊瑚岛礁遥感监测的基础。本文综合考虑珊瑚岛礁的形成机制、珊瑚礁形态和高分辨率遥感影像上珊瑚岛礁图斑的可解译程度等因素,制定应用于珊瑚岛礁高分遥感监测的分类体系,将珊瑚岛礁分为珊瑚岛、沙洲、干出珊瑚礁、珊瑚暗礁、珊瑚暗沙和珊瑚暗滩6个一级类型;并在现场调查数据的辅助下,从遥感影像上的色、形、位等特征方面建立珊瑚岛礁不同类型的遥感解译标志,结果可服务于南海珊瑚岛礁的动态监测,进而为珊瑚岛礁的保护、可持续利用和安全管理提供数据支撑。 相似文献
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南沙岛礁的发育受空间位置、暴露面积及地质结构等因素的影响,礁体的演变伴随空间形态的变化。本文利用遥感和地理信息系统(GIS)相结合的方法绘制南沙岛礁核密度现状图,并采用Kernel Density进一步分析南沙礁群空间核密度分布。研究表明:南沙岛礁空间形态复杂,有明显区域格局性,面积差异较大的岛礁核密度聚集位置不相同,分布特征相对密集。岛礁数量在纬度方向有明显浮动,在经度方向上趋于稳定。随礁体面积的增大,礁体平均形状指数逐渐增大,平均紧凑度逐渐减小,形状指数LSI介于0.90～2.87之间、紧凑度RC介于0.31～0.97之间。研究结果有助于更好地了解南沙岛礁密度情况,为海洋管理人员提供参考信息。 相似文献
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岛屿岛礁海域海浪能谱模型研究进展 总被引：2，自引：0，他引：2
波浪能谱模型在岛屿岛礁海域的波浪预报研究和海洋工程中应用广泛,但存在模式计算格点无法充分体现岛屿岛礁的复杂地形特征和很难刻画波浪受到岛屿岛礁影响发生变形物理过程等两个关键问题。多重网格嵌套方案、岛屿次网格地形效应计算方案以及非结构网格、无网格、动态自适应四叉树网格等技术在体现岛屿岛礁复杂地形方面取得了较好的效果;将相位解析模型与波浪能谱模型优势互补是提高能谱模型对岛屿近岸波浪变形物理过程计算能力的一个有效方法。开展球坐标系下波作用密度谱方程的自适应四叉树网格求解方法研究,借鉴相位解析模型最新成果完善能谱模式的绕射、反射、底摩擦等物理过程,是提高岛屿岛礁海域海浪精细预报技术水平的前沿性、探索性研究方向。 相似文献
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薛春汀 《海洋通报(英文版)》2004,6(2):45-50
Excavating sands and gravel on land in combination with constructing reservoirs for storing fresh water is an ideal approach in atolls. Appropriate mining of gravel from the prograding gravel beach is acceptable. Digging reef rock close to the edge of the wide ocean reef flat without surface loose sediments on it or sand beach can be accepted. Excavating sand from some depths in lagoon is a scientific approach particularly important for urbanized atolls. However, selecting appropriate sites for mining sand other than at some depths in lagoon is suitable to rural islands without dense populations. These sites include up drift side of long groin on the reef flat,partly filled access channel-port, outlet of artificial channel and lagoon margin on the prograding coast. 相似文献
9.
在海洋环境变化和人类活动的双重影响下,我国珊瑚礁白化现象日趋严重,珊瑚礁健康状况、珊瑚种群数量和丰富度呈逐年下降的趋势。本文基于2005-2007年QuickBird卫星影像、2011-2012年QuickBird/WorldView-2卫星影像和2016-2018年GF-1/2卫星影像等3期高分辨率遥感数据,以西沙永乐群岛羚羊礁、中建岛等14个岛礁为研究区（以下统称永乐群岛）,利用支持向量机（support vector machine,SVM）分类方法结合人机交互信息提取方法完成了3期永乐群岛的珊瑚礁底质类型分类,并通过珊瑚礁底质类型变化分析了永乐群岛珊瑚礁白化特征。主要结论包括：（1）提出了一种珊瑚礁白化程度分级的方法,将永乐群岛白化状况分为轻度、中度、重度和严重白化4个等级,通过分析发现在监测时段内14个岛礁中有13个发生了不同程度的白化,其中10个发生了重度白化（白化率20%以上）,1个严重白化（羚羊礁,白化率为33.36%）;（2）根据监测数据统计,上述珊瑚岛礁的白化主要是由珊瑚丛生区白化引起的,2005-2018年永乐群岛珊瑚丛生区白化面积占总的发生白化区域面积的70.55%;（3）14个岛礁中只有甘泉岛的活珊瑚覆盖在逐渐增加,活珊瑚覆盖面积由2006年5月10日的87.13 hm2增加到2018年3月7日的107.80 hm2。 相似文献
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岛礁珊瑚砂环境中存在着大量未被培养和利用的微生物资源, 微生物多样性研究是了解微生物生态功能、开发和利用微生物资源的基础。文章采用多种寡营养培养基选择性分离南海岛礁珊瑚砂中的可培养细菌, 共获得纯培养细菌菌株349株, 通过16S rRNA基因序列分析, 发现它们隶属于4门(Actinobacteria、Proteobacteria、Firmicutes和Bacteroidetes)、6纲、26目、43科、73属、134种, 可培养细菌的优势类群为放线菌门, 占所有分离菌株数量的60%; 而且还发现18个16S rRNA 基因序列相似性低于97%的潜在新种。本研究使用改良优化的寡营养培养基进行分离, 较好地显示出样品中微生物的群落组成, 且获得了大量潜在的稀有新物种资源。研究结果表明, 岛礁珊瑚砂样品的可培养细菌资源十分丰富、细菌群落所涉及的生态功能完整、潜在新种比例较高, 为后期岛礁微生物资源挖掘打下了良好的基础, 也为后期开发应用积累了丰富且稀有的菌种资源。 相似文献
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Reef development varies considerably around the high, raised‐limestone islands of the Commonwealth of the Northern Mariana Islands (CNMI). Here we examine the modern assemblages at 30 sites for coral composition, colony density, colony size, and fidelity. We defined four reef types and hypothesize the presence of environmentally driven ecological stasis, whereby the environment continuously selects for coral species membership, defines colony sizes, and over time creates the noted reef types. Our results show that constructional spur‐and‐groove reefs supported significantly larger coral‐colony sizes and higher coral species richness compared with high‐relief interstitial framework, low‐relief incipient, and non‐constructional coral assemblages. Non‐constructional reefs supported much smaller coral colony sizes, despite similar population densities, and were consistently found in association with high wave exposure. The distinct coral assemblages found on interstitial framework and low‐relief incipient reefs were not affiliated with any wave exposure regime, but were located adjacent to large watersheds and on islands with unique geological history. These assemblages were nested within the spur‐and‐groove species pool. Overall, modern coral cover was well predicted by bathymetric slope and watershed size, while species richness was additively influenced by two proxies of pollution, suggesting the latter is better suited for establishing management targets. In contrast with previous studies that suggested modern assemblages were biologically controlled in the CNMI, we show reef assemblages and reef development are highly influenced by long‐term environmental forcing. 相似文献
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本研究基于系统复杂性原理, 提出了南海典型珊瑚礁生态系统健康评价方法——组织力及系统功能评价法。该方法的评价框架包括珊瑚礁生态系统结构及功能、珊瑚礁生态系统与其他海洋生态系统间关系、与人类社会生态系统间关系、珊瑚礁生态系统发展制约因素等四大模块; 评价指标体系分为目标层、准则层、因素层、要素层等6个层级共计67个指标。同时, 本研究系统地提出了珊瑚礁生态系统健康评价的流程, 提高了珊瑚礁健康评价工作的规范性和时效性。应用组织力及系统功能评价法对2011—2018年西沙群岛珊瑚礁生态系统进行了健康评价, 结果显示自2011年起健康指数年均下降2.3%~2.4%, 除2012年、2015年健康指数稍有回升外, 其余年份均呈下降走势, 整体评价为亚健康状态。根据七连屿周边岛屿的实地考察和居民生活问卷调查结果, 2006—2008年的渔业发展、2012年的海星泛滥和2014—2015年的岛礁建设均对珊瑚礁生态系统造成了较大影响, 使10年内渔业产量下降了50%~80%。这与应用组织力及系统功能评价法的评价结果相吻合, 侧面验证了该评价方法的科学性和可行性。 相似文献
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Angela Marina Canterle Lucas Teixeira Nunes Luisa Fontoura Hugulay Albuquerque Maia Sergio Ricardo Floeter 《Marine Ecology》2020,41(5):e12609
The benthic assemblage of reefs provides an important resource of food and habitat for reef fishes. However, how benthic composition mediates reef fishes' biotic interactions at isolated environments such as oceanic islands remains largely unknown. Here, we aimed to investigate the role of four different reef microhabitats over biological interactions of fishes in an understudied oceanic island, Príncipe Island. For that, we recorded a total of 46 Underwater Remote Videos (RUVs) to document benthic composition and fishes' trophic and agonistic interactions. We used benthic cover estimates to group the samples into four microhabitats (dominated by epilithic algal matrix [EAM], sand/rock, corals and sponges), then quantified fishes' trophic and agonistic interactions in each microhabitat. All microhabitats presented a different structure of trophic and agonistic interactions of the fish assemblage. Feeding pressure (FP) and agonistic interactions were higher on the EAM microhabitat and lower in coral microhabitat. Herbivores were the main responsible group for the FP in all microhabitats. Territorial damselfishes used microhabitats differently for both trophic and agonistic interactions. We demonstrated that reef fish diversity and intensity of biotic interactions varied according the spatial distribution of benthic resources, which suggests that benthic composition plays an important role on structuring biological interactions at isolated reef systems. 相似文献
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渤海湾西北岸滨海湖埋藏牡蛎礁古生态环境 总被引：2，自引：0，他引：2
对渤海湾西北岸沿海平原滨海湖埋藏牡蛎礁的分布形态进行了综合调查,并对位于礁体中央部位的一个垂直剖面上的礁体下伏沉积物、礁体内的泥砂质充填物连续取样。综合研究表明,该埋藏礁体生长于河流入海口处,长轴方向NW—SE、沿古河床分布。礁体开始建造于2445aBP前,基底坐落于当时的潮间带下部。持续建礁约160年后,至2287aBP时,礁体建造至潮间带中部海平面位置。随着岸线的推进,河流携带的大量泥砂逐渐掩埋了平均厚度约2m的滨海湖牡蛎礁。 相似文献
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《Marine Policy》2017
Groupers are highly targeted and vulnerable reef fishes. The effects of fishing pressure on the density of three reef fishes were investigated in 21 islands outside (n=15) and inside (n=6) a Marine Protected Area (MPA) at the Paraty Bay, Brazilian southeastern coast. Two valued groupers (Epinephelus marginatus and Mycteroperca acutirostris) and a non-target grunt (Haemulon aurolineatum) were studied. The total biomass of fish caught in each island was considered as a measure of current fishing pressure, while the island distance from the villages was considered as a measure of past fishing pressure. Fish densities were recordedin number and biomass. The biomass of M. acutirostris was inversely related to current fishing pressure, which did not affect the other two fishes. The density of E. marginatus increased with the island distance from one of the fishing villages, which indicated that past fishing may have had decreased the abundance of E. marginatus. Densities of the three fishes and fishing pressure did not differ between islands inside and outside the MPA. Data on fishing pressure, densities of groupers and coral cover were combined here to assign conservation scores to islands. A redefinition of MPA boundaries to reconcile fish conservation, fishing activities and fishers’ food security was proposed. 相似文献
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江苏岸外的小庙洪牡蛎礁在海岸地貌学上是一稀有的生物沉积体。这种位于蚀、淤交替岸段潮间带、古礁体和活体共存的牡蛎礁体是我国所仅见。现场观察了牡蛎礁体的地貌特征,并使用GPS和全站仪进行了主要礁体分布与高程的测量,表明礁区地貌面不是一个水平面,相差可达2m以上。礁体顶高主要分布在两个高程上,一是与平均潮位相当,二是比前者低约30cm,略高于小潮平均低潮位。礁体起伏面高出礁坪面多在0.5—1.5m。小庙洪牡蛎礁正处于退化状态,除物理因素造成的侵蚀外,化学溶蚀及人类活动也是侵蚀退化的主要因素。对于礁区内部的礁体,其退化过程为连片礁→环礁→带礁→斑礁→礁坪的顺序。礁体沉积体有三种:原生礁体、与原生礁体脱离的礁块以及已离开原生地的松散堆积体。浪蚀礁坪分布在礁体的迎浪面上,而溶蚀礁坪则分布在礁体密集区。在礁体稀疏区,则覆盖约20—30cm厚的粉沙或淤泥,形成次生的潮坪。 相似文献
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