南沙美济礁滨珊瑚骨骼密度条带的变化

结合珊瑚骨骼X射线照片和δ18O、δ13C的年际变化,对南沙群岛美济礁滨珊瑚骨骼岩心的密度条带进行了分析,发现其密度带变化模式多样,初步可归纳为如下3种类型:(1)宽度相近的高低密度条纹均匀、相间地排列,一对高低密度条带平均宽约4 mm;(2)在骨骼主生长轴上由近于均匀分布的细密度条带组成,高低密度条带对平均宽约4 mm,但在主生长轴的两侧,多条细密度条带合成一条较宽的密度条带,高低密度条带对平均宽约10mm;(3)主生长轴上和其两侧的骨骼密度条带均由细密度条带组成,合成的高低密度条带宽分别约7和4 mm。与滨珊瑚骨骼δ18O的对比分析表明,第1种类型的细密度条带对不代表骨骼一年的伸长量,因为高低密度带和δ18O的峰值和谷值之间不存在统计学上的关系。第2种和第3种类型中由细条带组成的宽的高低密度条带对很可能是年周期性的。     

全球变暖和核电站温排水对大亚湾滨珊瑚钙化的影响

全球变暖引起的珊瑚白化和珊瑚钙化能力减弱,对全球珊瑚礁生态系统构成了严重威胁.在这样的背景下,相对高纬度海域石珊瑚(Scleractinia)群落被认为是珊瑚物种延续的最后避难所.通过分析大亚湾海域持续生长46年(1962-2007年)的滨珊瑚Porites骨骼参数(生长率、密度和钙化率),研究相对高纬度海域石珊瑚钙化对全球变暖以及人为热排放的响应模式.结果显示,滨珊瑚平均生长率、密度和钙化率分别为0.97cm·a-1(0.41-1.32cm·a-1)、1.45g·cm-3(1.17-1.65g·cm-3)和1.40g·(cm2·a)-1[0.59-1.93g·(cm2·a)-1].海表温度(SST)是该海域石珊瑚钙化的主导控制因素.1962-1993年,全球变暖、SST上升对大亚湾滨珊瑚生长有缓解冬季低温胁迫、促进骨骼钙化的作用.然而,随着SST持续上升以及大亚湾核电站的运行,全球变暖与核电站温排水对滨珊瑚骨骼形成高密度带造成抑制作用,导致自1993年以后滨珊瑚骨骼生长率和钙化率呈下降趋势,并出现1997-2001年和2006年的低谷.因此,全球变暖,至少是初期,对相对高纬度海域石珊瑚钙化乃至珊瑚礁发育是有促进作用的.但随着SST持续上升,加上ENSO等极端高温事件以及人类活动的影响,可能在未来会出现相对高纬度海域的大面积石珊瑚白化.     

海南岛三亚滨珊瑚生长率特征及其与环境因素的关系

海南岛三亚不同珊瑚岸礁区两个不同生长年取滨珊瑚样品的生长率具有明显的季节变化特点，冬季生长率低，春季至秋季生长率高，并获取了滨珊瑚的季节生长率时间变化序列，珊瑚生长率与主要环境因素的对比表明，滨珊瑚的生长率主要与海水温度相关，而与降水和日照时数的相关性不明显，春季和夏季的生长率与冬季和早春（12～3月）的海水温度相关，其他季节的生长率与海水温度的季节变化关系不明显，初步认为低海水温度及三亚岸礁区浓珊瑚季节生长率变化的主要环境控制因素之一。     

单轴抗压强度揭示南海珊瑚骨骼结构的差异

通过单轴抗压强度测试法,测量南海北部涠洲岛和南部南沙群岛美济礁块状珊瑚骨骼的抗压强度,将工程力学和珊瑚礁地质生态学相结合,用定量的数据揭示南海南、北部珊瑚骨骼结构的差异性。结果表明,美济礁珊瑚的单轴抗压强度近3倍于涠洲岛样品,显示涠洲岛珊瑚的承载能力相对较弱。南沙群岛海域珊瑚样品的力学性质呈弹性曲线规则变化,而涠洲岛珊瑚的抗压强度时间曲线呈现不规则变化,有不断压密、调整、再压密的过程。通过对破坏后样品的观察,涠洲岛样品的破坏并没有发生在沿生长轴线的方向,而是在孔洞和骨骼密度小的部位。生物侵蚀加重、孔洞增多导致涠洲岛珊瑚骨骼结构的改变,进一步导致了珊瑚不仅抗压强度差、承载力下降,而且力学性质紊乱。该研究工作用定量的数据论证了海水污染对珊瑚骨骼结构改变的影响,建议开展岛礁工程、生态修复等工作之前的首要任务是保护水质、控制排放、有效治理海水污染。     

近165年来中沙环礁中北暗沙滨珊瑚生长率及其对海温变化的响应

海水温度是控制珊瑚生长的关键环境因素之一, 随着全球气候变暖, 海温持续升高已成为珊瑚生长面临的全球性威胁。文章对采自中沙环礁中北暗沙水深约16m的澄黄滨珊瑚岩心样品开展了生长率分析, 揭示出中沙环礁滨珊瑚近165年来的生长历史及变化规律; 并通过与西沙群岛永兴岛滨珊瑚生长率的对比, 探讨了南海中部滨珊瑚生长的区域差异及其对海温升高的响应关系。过去100多年来中北暗沙和永兴岛海区的平均海温分别为(27.4±0.37)℃和(27.09±0.36)℃, 两个海区的海温均呈线性升高趋势, 升温速率一致, 约为0.43℃·ha^-1。过去100多年间中北暗沙和永兴岛滨珊瑚的平均生长率分别为(0.70±0.16)cm·a^-1和(1.19±0.16)cm·a^-1, 但中北暗沙滨珊瑚生长率呈线性下降趋势, 下降速率约为9.4%·ha^-1; 而永兴岛滨珊瑚生长率呈线性上升趋势, 增长速率约为10.9%·ha^-1。过去100多年间两个礁区的滨珊瑚生长率均存在年代际波动, 大致与海温的年代际波动对应。两个礁区滨珊瑚生长率与海温在趋势上呈现非线性响应关系, 存在滨珊瑚生长的最适宜温度约为27.25℃, 过去100多年来中北暗沙海域海温的增温趋势已经超出了滨珊瑚生长的适宜海温范围, 限制了滨珊瑚的生长趋势, 而永兴岛海域海温仍适宜滨珊瑚的生长。在年代际波动上两个礁区滨珊瑚生长率与海温存在线性正相关关系, 海温的年代际增温有利于滨珊瑚生长。在南海未来持续海水升温的情况下, 中北暗沙珊瑚生长的下降趋势将会进一步加剧, 并将严重威胁中沙珊瑚礁生态系统的维持和发展。     

稀土元素地球化学在珊瑚礁环境记录中的研究进展

综述了稀土元素地球化学在珊瑚记录过去环境变化和珊瑚对环境变化响应等方面的研究进展。珊瑚骨骼中的稀土元素能够记录的环境信息主要包括海平面、污染、地下水、氧化还原环境等;而在珊瑚对环境变化的响应方面,主要体现在稀土元素的含量,配分型式以及Ce、Eu等元素的异常上。珊瑚骨骼中的稀土元素因为具有稳定性高、保存信息丰富以及记录环境准确等优势,显示出了极好的应用前景。未来的研究中,需要进一步探索珊瑚骨骼稀土元素含量的种间及空间差异性,探讨成岩作用对珊瑚骨骼稀土元素含量和配分型式的影响,这将有利于重建更准确、更长时间序列的珊瑚生长时期的环境信息记录。     

热带海洋环境研究的新代用指标——造礁珊瑚14C记录

造礁珊瑚具有独特的生物学和生态学特性 ,珊瑚骨骼生长带详细记录了珊瑚生长的历史和环境变化信息 ,具有高精度、高分辨率的特点 ,是研究热带海洋环境的重要信息载体。造礁珊瑚及其环境记录已成为国际上最重要和最活跃的研究前沿之一 ,多个国际研究计划都提出利用珊瑚高分辨率的代用指标进行热带海洋气候、环境变化历史的重建研究［１～３］。近年来 ,随着物理、化学等分析测试技术的发展 ,珊瑚环境代用指标的研究获得了重大突破 ,其中以热带海洋表层海水温度 (ＳＳＴ )的研究最为广泛 ［３，４］,已经建立了分辨率可达年、月甚至周尺度的珊…     

鹿角杯形珊瑚骨骼构造和显微结构的研究

石珊瑚骨骼对重建古海洋古气候环境,评估珊瑚礁对未来气候变化、海洋酸化的响应和反馈,辨识现存造礁石珊瑚种属及其演化途径有着十分重要的作用和意义。为了更好地认知造礁石珊瑚骨骼特征,在三亚海域采集了常见的造礁石珊瑚——鹿角杯形珊瑚Pocillopora damicornis,通过扫描电镜(结合EDS能谱仪)、红外分光显微镜分析其碳酸钙骨骼结构和成分的特征,结果表明鹿角杯形珊瑚骨骼主要成分为文石,少数骨骼样品的空腔中发育有极少量方解石矿物。虽然鹿角杯形珊瑚骨骼宏观架构和中观架构在群体间和单体间存在诸多差异,但不同形态的骨骼样品具有基本相同的发育模式和基础结构单元。同时,发现鹿角杯形珊瑚骨骼内部空腔存在有次生文石沉积发育现象,同时常伴生着水镁石矿物的发育,而且这与骨骼中的钻孔穴居动物有很大关联。     

南海北部滨珊瑚微结构的SEM分析及其对气候记录重建的意义

造礁珊瑚是重建高分辨率的古气候变化记录的理想载体,而珊瑚骨骼的微结构反映珊瑚的生长特征,了解珊瑚的微结构有助于更好地理解珊瑚的古气候记录。利用扫描电镜分析了南海北部三亚和北海一些中全新世及现代滨珊瑚的微结构。在低放大倍数下(<1 000倍)观察到珊瑚单体、隔壁、隔壁齿、孔洞、隔膜、共骨、横梁等结构。在高放大倍数下(≥1 000倍)观察到具有鹅卵石状、蔟状、柱状及针状4种文石晶体的基本类型及文石晶体组成的钙化中心、隔膜等结构。根据这些基本微结构变化特征,可以清楚分辨出珊瑚死亡-恢复生长界线,并可观察到珊瑚的文石晶体是否受到后期蚀变的影响,例如充填、重结晶等。在所分析的三亚、北海滨珊瑚样品中,冬季最冷及夏季最热时期均没有发现死亡-恢复生长界线,指示持续生长的方式。经过测量,珊瑚隔膜横向延展形成的纹层生长时间约为一个月,这对于利用微区分析建立精细的超过月分辨率的气候记录具有重要意义。微结构显示北海地区的老珊瑚暗层具有较多的杂质充填,结合氧同位素地球化学记录的变化特征,可以发现这些暗层形成于夏季,受高温以及海水强烈扰动而导致生长速率减缓所致。     

海水电沉积作用碳酸钙结晶与珊瑚骨骼晶体的比较

电沉积促进珊瑚生长和岸礁修复技术是国际上常采用的生态修复方法,但电沉积技术中电流条件与沉积晶体之间的关系却鲜有研究,关于其形成的电沉积物的晶体结构的报道更是少有。本文探索了在不同电流密度的条件下海水形成碳酸钙晶体的特点,并与珊瑚骨骼晶体进行了对比。本实验设置了300、600、900和1200 m A/m2四组电流密度,在海水中进行5 d电沉积反应,实验后称量了阴极上形成的电沉积物质量,用扫描电子显微镜和X-射线衍射分析了电沉积物中晶体特点并与珊瑚骨骼进行了比较。结果发现,随着电流密度增大,电沉积物质量增加,电流密度为600 m A/m2条件下电沉积物形成的速率与南海的滨珊瑚的生长速率相当。在各个电流密度梯度条件下形成的晶体均与珊瑚骨骼的晶体结构相似。较低电流密度下电沉积物中碳酸钙比例较高。其中,在电流密度为600 m A/m2的条件下,形成的沉积物碳酸钙文石比例最高,和珊瑚骨骼晶体最为接近。本研究为促珊瑚生长的电沉积技术提供了基础数据和理论。     

Characteristics of Growth Rate of Coral Porites from Sanya Bay, Hainan Island and its Relationship to Environmental Variables

The time series of annual and seasonal growth rate of two coral Porites, collected at different sites of fringe reef in the Sanya Bay, Hainan Island have been obtained by analyzing X-radiograph of skeletal band. There are obvious seasonal variations of the growth rate in two corals, the average low rate in winter and the average high rate from spring to autumn. Compared with the time series of environmental variables, the coral growth rote is only correlated statistically with seawater temperature and not related to rainfall and sunshine. Furthermore, the growth rate in spring and summer is correlated directly with seawater temperature of the winter-early spring ( between December and March ) and the other seasonal growth rate has no relationship with seasonal variations of seawater temperature. We propose that seawater temperature is one of the factors affecting the coral growth rate in the area and the low seawater temperature is a primary control of the seasonal growth rate.     

Bioerosion by the sea urchin Diadema mexicanum along Eastern Tropical Pacific coral reefs

Bioerosion is a natural process in coral reefs. It is fundamental to the health of these ecosystems. In the Eastern Tropical Pacific (ETP) coral reefs, the most important bioeroders are sponges, bivalves, sea urchins and the fish Arothron meleagris. In the 1980s, El Niño caused high coral mortality and an increase in macroalgal growth. As a result, greater sea urchin bioerosion occurred. This weakened the reef framework. Considering the high vulnerability of the ETP coral reefs, the goal of this study was to determine the current bioerosion impact of the sea urchin Diadema mexicanum along the western coasts of Mexico, El Salvador, Costa Rica and Panamá. The balance between coral bioaccretion and sea urchin bioerosion was also calculated. Between 2009 and 2010, in 12 coral reefs localities, D. mexicanum density, bottom cover and rugosity were quantified along band transects. The daily bioerosion rate was obtained from the amount of carbonates evacuated by sea urchins per unit time. The rate of coral accretion was calculated by multiplying the coral growth rate of the dominant genus by the density of their skeleton and by their specific coral cover. The localities were dissimilar (R = 0.765, P < 0.001) in terms of live coral cover, crustose calcareous algae, turf cover, rugosity index, and density and size of D. mexicanum. At all sites, with the exception of Bahía Culebra (Costa Rica), coral bioerosion was less than coral bioaccretion. Diadema mexicanum plays a dominant role in the balance of carbonates in the ETP, but this depends on reef condition (protection, overfishing, eutrophication) and so the impacts can be either positive or negative.     

Low calcification rates and calcium carbonate production in Porites panamensis at its northernmost geographic distribution

Porites panamensis is a hermatypic coral present in the eastern Pacific Ocean. Skeletal growth parameters have been reported, but studies of the relationship between annual calcification rates and environmental controls are scarce. In this study, we investigated three aspects of the annual calcification rates of P. panamensis: growth parameters among three P. panamensis populations; the sea surface temperature as a calcification rate control spanning a latitudinal gradient; and calcium carbonate production among three sites. Growth parameters varied among the sites due to the colony growth form. Massive colonies in the north showed a higher calcification rate than encrusting colonies in the south (mean: 1.22–0.49 g CaCO₃ · cm^?2 · yr^?1), where variations in calcification rates were related to growth rate (0.91–0.38 cm · yr^?1) rather than to skeletal density differences (overall mean ± SD, 1.31 ± 0.04 g CaCO₃ · cm^?3). Our results showed a positive linear relationship between annual calcification rates and sea surface temperatures within these P. panamensis populations. Differences were related to distinct oceanographic environments (within and at the entrance of the Gulf of California) with different sea surface temperature regimes and other chemical properties. Different populations calcified under different environmental conditions. Calcium carbonate production was dependent upon the calcification rate and coral cover and so carbonate production was higher in the north (coral cover 12%) than in the south (coral cover 3.5). Thus, the studied sites showed low calcium carbonate production (0.25–0.43 kg CaCO₃ · m^?2 · yr^?1). Our results showed reduced calcification rates, regional temperature regime control over calcification rates, different growth forms, low coral cover and low calcium carbonate production rates in P. panamensis.     

Coral assemblages and reef growth in the Commonwealth of the Northern Mariana Islands (Western Pacific Ocean)

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.     

丛生盔形珊瑚共生体及骨骼的形态研究

"共生"和"钙化"一直是珊瑚生物生态学研究中两个最核心的问题,为加深对珊瑚共生和钙化生物过程的理解,以丛生盔形珊瑚(Galaxea fascicularis)作为研究模型,通过透射电镜和扫描电镜研究珊瑚共生体的细胞显微结构及骨骼的形态特征,并利用电感耦合等离子体质谱(Inductively Coupled Plasma...     

全球变暖背景下三亚湾上升流的冷水有利于珊瑚的生存

It has been reported that global warming has negative effects on coral ecosystems in the past 50 years and the effects vary in different ocean environment. In order to make clear the coral reef status in the background of global warming along the south coast of Hainan Island of China, satellite and in situ data are used to retrieve the information of the coral reef status and surrounding environmental factors. The results show that cool water induced by upwelling along the south coast of Hainan Island is found in the area every summer month, especially in the relatively strong El Ni?o years(2002–2003 and 2005). From the NOAA satellite data, degree heating week(DHW) index does not exceed 3 in Sanya Bay even in the relatively strong El Ni?o years. By comparison of a coral reef growth rate in the Sanya Bay with respect to El Ni?o events from 1957 to 2000, coral's growth rate is relatively greater during 1972, 1991–1994 and 1998 El Ni?o event. By analyzing the environmental factors, it is found that the cool water induced by upwelling may be the main reason for protecting corals from global warming effects.     

南海珊瑚岛礁地貌遥感识别研究

南海珊瑚岛礁总体处于退化状态,卫星遥感可以实现珊瑚礁区底质演变的监测.本文以西沙群岛海域赵述岛为研究区域,以Landsat-8卫星遥感影像为研究数据,对浅海地貌变化进行遥感分析.将影像进行水深校正和波段组合,使用最大似然法进行珊瑚礁地貌分类,可以清晰的识别灰沙岛、礁坪、礁前坡、泻湖坡、暗滩和海面六种地貌类型,以Worl...