Diversity and distribution of bacterioplankton in the coastal upwelling waters off Hainan Island,China

The diversity,community composition and 16 S rRNA gene abundance of bacterioplankton along a transect across an upwelling area off the eastern coast of Hainan Island(the Qiongdong upwelling)were investigated in August of 2016 using high throughput sequencing and quantitative PCR assay of 16 S rRNA genes.Compared with the offshore stations,the inner-shelf stations had higher bacterial gene abundance(up to 3 fold)and operational taxonomic unit richness,a result of the influence of upwelled and fresher waters.Overall,a majority of the reads were affiliated with Gammaproteobacteria(11%-74%)and Alphaproteobacteria(14%-43%).The structure of the bacterial community was significantly affected by salinity,dissolved oxygen,NO_(3)^(-) and NH_(4)^(+),which also defined the physicochemical features of the upwelled waters.Horizontally,the relative abundances and gene abundances of Rhodobacteraceae,SAR86,Cyanobacteria and Bacteroidetes in eutrophic zone decreased from the inner to outer shelves and slope,whereas Alteromonas,Vibrio and Oceanospirillaceae exhibited an opposite trend.This study stresses the riverine influence on the oceanographic condition and spatial variability of bacterioplankton diversity and distribution in the Qiongdong upwelling.

Geomorphology of the Boao coastal system and potential effects of human activities-Hainan Island,South China

The Boao coastal system along the eastern coast of Hainan Island is a dynamic delta-tidal inlet-barrier formed during the late Holocene. The delta developed inside a shallow lagoon barred by a sandy barrier with a narrow, shallow tidal inlet opening. Two major distributary channels separated by small islands characterize the delta. The lagoon is silting up receiving and trapping sediments from both the river and, in minor measure during storms, through the tidal inlet opening and barrier washovers. The barrier at the tidal inlet is highly dynamic and changes its form, accreting (migrating spit) against the inlet during fair-weather conditions and being eroded during storms and river floods. The delta has almost completely filled the lagoon and major concerns exist on the effect that ongoing large development plans may have on the environment. These concerns include the effect on floods and rate of siltation once banks of the islands have been stabilized and floodwater and sediment load are impeded from spreading over the lowlands, and the effect of increasing pollutant loads from the new facilities on the ecosystems of the increasingly restricting lagoon water and on the seashores.

^(226)Ra and ^(228)Ra tracer study on nutrient transport in east coastal waters of Hainan Island,China

Material fluxes （e.g., nutrients） from coastal waters to offshore areas play an important role in controlling the water quality of the adjacent sea areas not only by increasing nutrient concentration hut also by changing nutrient structures. In this study, naturally occurring isotopes, ^226Ra and ^228Ra, were measured with the alpha spectrometry in the Wenjiao-Wenchang and Wanquan estuaries and adjacent sea areas along the east coast of Hainan Island. The excess ^226Ra and ^228Ra activities were observed by comparison with the values derived from the conservative mixing of freshwater and seawater end-members in both estuaries. Using a one-dimensional diffusion model, the horizontal eddy diffusion coefficient of 3.1 6 × 10^5 cm^2/s, for nutrients diffusing from their sources, was derived from 228Ra activities. Consequently, the corresponding nutrient fluxes flowing into the coastal waters were assessed. The results can provide useful information for the study of the mixing and exchange processes of coastal waters as well as dissoluble pollutant transport in this sea area.

Reconstructing Environmental Changes of a Coastal Lagoon with Coral Reefs in Southeastern Hainan Island

Coastal lagoons with small catchment basins are highly sensitive to natural processes and anthropogenic activities. To figure out the environmental changes of a coastal lagoon and its contribution to carbon burial, two sediment cores were collected in Xincun Lagoon, southeastern Hainan Island and (210) ~Pb activities, grain size parameters, total organic carbon(TOC), total nitrogen(TN), total inorganic carbon(TIC) and stable carbon isotopes(δ^(13)C) were measured. The results show that in 1770–1815, the decreasing water exchange capacity with outer open water, probably caused by the shifting and narrowing of the tidal inlet, not only diminished the currents and fined the sediments in the lagoon, but also reduced the organic matter of marine sources. From 1815 to 1950, the sedimentary environment of Xincun Lagoon was frequently influenced by storm events. These extreme events resulted in the high fluctuation of sediment grain size and sorting, as well as the great variation in contributions of terrestrial(higher plants, soils) and marine sources(phytoplankton, algae, seagrass). The extremely high content of TIC, compared to TOC before 1950 could be attributed to the large-scale coverage of coral reefs. However, with the boost of seawater aquaculture activities after 1970, the health growth of coral species was severely threatened, and corresponding production and inorganic carbon burial flux reduced. The apparent enhanced inorganic carbon burial rate after 1990 might result from the concomitant carbonate debris produced by seawater aquaculture. This result is important for local government long-term coastal management and environmental planning.

A wind tunnel simulation of the dynamic processes involved in sand dune formation on the western coast of Hainan Island

The western coast of Hainan Island exhibits a savanna landscape. Many types of sand dunes, including transverse dune ridges, longitudinal dune ridges, elliptical dunes, coppice dunes, and climbing dunes, are widely distributed in the coastal zone. In winter, high-frequency and high-energy NE winds （dominant winds） are prevalent, with a resultant drift direction （RDD） of S35.6°W. In spring, low-frequency and low-energy SW secondary winds prevail, with a RDD of N25.1°E. Wind tunnel simulations revealed that the airflow over the dune surface is the main factor controlling the erosion and deposition patterns of dune surfaces and the morphological development of dunes. In the region＇s bidirectional wind environment, with two seasonally distinct energy levels, the airflow over the surface of elliptical dunes, barchan dunes, and transverse dune ridges will exhibit a transverse pattern, whereas the airflow over longitudinal dunes ridges exhibits a lateral pattern and that over climbing dunes exhibits a climbing-circumfluent pattern. These patterns represent different dynamic processes. The coastal dunes on the western coast of Hainan Island are influenced by factors such as onshore winds, sand sources, coastal slopes, rivers, and forest shelter belts. The source of the sand that supplements these dunes particularly influences the development pattern： when there is more sand, the pattern shows positive equilibrium deposition between dune ridges and dunes; otherwise, it shows negative equilibrium deposition. The presence or absence of forest shelter belts also influences deposition and dune development patterns and transformation of dune forms. Coastal dunes and inland desert dunes experience similar dynamic processes, but the former have more diversified shapes and more complex formation mechanisms.

Mean water level setup/setdown in the inlet-lagoon system induced by tidal action—a case study of Xincun Inlet,Hainan Island in China

With the tides propagating from the open sea to the lagoon, the mean water level （MWL） in the inlet and lagoon becomes different from that at the open sea, and a setup/setdown is generated. The change of MWL （setup/setdown） in the system imposes a great impact on regulating the development of tidal marshes, on determining the long-term water level for harbor maintenance, on the planning for the water front development with the flood control for the possible inundation, and on the interpretation of the historical sea level change when using tidal marsh peat deposits in the lagoon as the indicator for open sea＇ s sea level. In this case study on the mechanisms which control the setup/setdown in Xincun Inlet, Hainan in China, the 2-D barotropic mode of Eulerian - Lagrangian CIRCulation （ELCIRC） model was utilized. After model calibration and verification, a series of numerical experiments were conducted to examine the effects of bottom friction and advection terms, wetting and drying of intertidal areas, bathymetry and boundary conditions on the setup/setdown in the system. The modeling results show that setup occurs over the inlet and lagoon areas with an order of one tenth of the tide range at the entrance. The larger the bottom friction is, a larger setup is generated. Without the advection term, the setup is reduced clue to a decrease of water level gradient to compensate for the disappearance of the advection term. Even without overtides, a setup can still be developed in the system. Sea level rise and dredging in the inlet and tidal channel can cause a decrease of setup in the system, whereas shoaling of the system can increase the setup. The uniqueness of the Xincun Inlet with respect to MWL change is that there is no evident setdown in the inlet, which can be attributed to the complex geometry and bathymetry associated with the inlet system.

Investigating internal waves east of the Hainan Island using optical satellite remote sensing data

Marginal water east of the Hainan Island is where internal waves occur frequently. Few studies have been conducted on these internal waves so far, and their formation mechanism remains unclear. In this study, the author uses the China-Brazil Earth Resources Satellite data (CBERS) to detect and calculate the distribution, direction, wavelength and amplitude of internal waves in this area. The results show that the direction of these internal waves is offshore and their wavelength is about 150-200 m. The internal waves can be postulated as formed by upwelling or reversed tide.

PRELIMINARY STUDY ON PISIONIDS (ANNELIDA:POLYCHAETA PISIONIDAE) FROM HAINAN ISLAND COASTAL WATERS,SOUTH CHINA SEA

the four species of Pisione Grube (1856) collected from the coastal watersof Hainan Island , the South China Sea , and described in this paper, Pisione hainanensis n. sp.is new to science , Pisione oerstedii Grube , 1857; Pisione complexa Alikunhi , 1947 , and Pisione levisetosa Zhao, Westheide & Wu, 1991 are reported for the first time from this area.

热带岛屿流域水生态评价理论研究与实践——以海南岛为例

为系统科学评估海南流域的水生态现状,本研究以海南岛为例,进行了热带岛屿流域水生态评价理论研究和实践.研究基于相关成果和流域突出水生态问题,构建了水生生物､水生境､水环境和水资源共11项指标的评价体系,综合利用专家打分和层次分析法计算了评价指标权重,并采用水生态环境质量综合评价指数(WEQI)对南渡江､昌化江和万泉河等海南岛典型流域开展水生态现状评价实践.结果表明:南渡江､昌化江和万泉河干流水生态为良好水平(63.77~71.57分),4座水库为一般水平(41.50~59.55分),水生生物是水生态提升的首要制约项,人为活动是水生态破坏的主要原因,水库还受生态需水量的限制.本研究构建的热带岛屿水生态评价体系可为当地水生态监测和评价提供科学依据.

浅析海南岛海岸带的有效保护与合理利用

海岸带的有效保护与合理利用已经成为沿海地区可持续发展的重要途径。文章在回顾海南岛海岸带保护利用研究的基础上,梳理取得的成效和存在的问题,阐释海岸带有效保护与合理利用的重要意义;基于海岸地质和海岸动力对海岸线的控制机理,深刻剖析海南岛海岸带独特而脆弱的生态特征、人类活动影响以及丰富的旅游资源,揭示海岸动力过程和海岸带的重要性以及大气、海洋、陆地如何相互作用;提出海南岛海岸带有效保护与合理利用的新概念,构建海南岛海岸带有效保护与合理利用的顶端战略模型。为促进海南岛海岸带的有效保护与合理利用,必须以生态平衡为本,加强对海岸动力过程的调查研究,科学评估旅游地的承载能力,适时开展资源数据挖掘与监测预警,启动海南岛海洋类世界自然遗产申报及建设工作,探索以“立法先行、统筹规划、宏观调控、科学支撑、财力保障、统一管理、公众参与”为核心的“海南模式”。

海南岛西部近岸海域碎屑锆石U-Pb同位素年代学物源示踪及其地质意义

海南岛西部近岸海域海砂资源丰富、经济价值巨大,对其物质来源却缺乏系统研究。为解决这一科学问题,为该区域海砂资源的开发利用提供科学依据,对海南岛西部近岸海域和昌化江入海口1 471粒碎屑锆石开展了U-Pb同位素年代学和微区元素地球化学研究。海南岛西部近岸海域年龄范围在3.45 Ga~82 Ma,具有99、241、252 Ma 3个主要年龄峰值,以及113、155、325、357 Ma 4个次要年龄峰值;昌化江入海口具有2.3 Ga~96 Ma的年龄范围,存在101、244、254 Ma 3个主要年龄峰值,以及122、266、281、307、342 Ma 4个次要年龄峰值。结果表明:海南岛西部近岸海域沉积物以具有~99 Ma的显著年龄峰,并缺乏晋宁期、加里东期和喜山期年龄峰为识别标志,海南岛应是其主要物源区,区内丰富的海砂资源来源于海南岛内岩浆岩和沉积岩的风化剥蚀和搬运沉积;海南岛西部近岸海域与昌化江沉积物年龄峰值的差异,指示海南岛西部近岸海域沉积物并非单纯来源于近源昌化江输入,也在北部湾逆时针环流的作用下接受琼西南部河流的物源贡献;更新昌化江入海口的碎屑锆石年龄组成,新识别出的380~310 Ma年龄群,可作为昌化江流域物源的识别标志;本次碎屑锆石年龄频谱特征与海南岛经历的多次重要地质事件相吻合,有助于了解海南岛复杂的地质演化历史。

基于环境DNA metabarcoding的西轩岛近海鱼类多样性研究

鱼类多样性的保护对于生态系统的科学管理和资源的可持续利用至关重要。环境DNA metabarcoding技术的出现和应用为水生生物的调查与监测带来了强有力的技术革新。本研究以浙江舟山近海岛屿——西轩岛为例,设计了4个不同采样站位,先后于2019年2月(冬季)、5月(春季)和11月(秋季)共采集水样12个,通过环境DNA提取、扩增、高通量测序以及生物信息学分析,对西轩岛近海鱼类多样性进行了分析,同时评估了鱼类多样性的时空差异。结果显示,共监测到鱼类33种,隶属于12目26科32属,其中,鲈形目(Perciformes)种类最多,共19种,约占所有种类的57.6%。不同采样季节的多样性指数和均匀度指数均存在显著差异,表明季节可能是影响西轩岛近海鱼类多样性的因素之一。综合时间和空间分析的结果显示,在繁殖季节且远离舟山本岛一侧的采样点监测到的鱼种数量更多。通过比对之前传统渔业资源调查的结果发现,不同季节优势种存在较大变化,可能与采样点数量较少且集中有关。进化树富集结果显示,各季节的优势鱼种与传统调查手段的结果有较大差异,表明目前环境DNA仍不能完全替代传统调查方法,但可以将环境DNA方法与传统的调查方法相结合,以确保监测结果的准确性和可靠性。

岛礁水沙动力学研究综述

珊瑚礁广泛分布于热带和亚热带浅水海域,是保护海岸带的天然屏障。近年来,受全球气候变化和人类活动的影响,全球的珊瑚礁持续出现了大规模白化现象进而发生退化。充分了解珊瑚礁海岸水沙动力过程是进一步认识珊瑚礁环境中各种物理、化学和生物过程的基础。南海岛礁是我国宝贵的陆地资源,也是建设“海上丝绸之路”和维护海洋权益的关键节点,关乎国家主权核心利益。当前,南海岛礁的防浪设施在台风等极端天气作用下的安全保障也亟须相关的水沙动力学理论作为支撑。本文基于当前国内外珊瑚礁海岸水沙动力学的研究进展,从珊瑚礁海岸波、流作用下的水动力特性与生态健康、珊瑚礁海岸低频长波运动与海岸防灾减灾、珊瑚砂运动与珊瑚砂岛演变、波浪与防浪建筑物相互作用及岛礁防护4个方面进行了分析和总结,并针对这4个方面提出了研究展望,旨在为今后岛礁水沙动力学的研究提供一定的借鉴和参考。

海南岛水稻需水量与缺水量的时空变化特征

为了掌握海南岛水稻需水量和缺水量的时空变化特征,基于海南岛18个市(县)1971—2020年的逐日气象数据和6个农业气象试验站早、晚稻生育期数据,采用Penman-Monteith公式和作物系数法及美国农业部土壤保持局推荐的方法计算早、晚稻需水量和缺水量,并分析其时空变化特征。结果表明:近50年海南岛早、晚稻全生育期需水量分别为444.9、419.7 mm,全生育期缺水量分别为337.1、186.9 mm。早、晚稻全生育期需水量和缺水量空间分布各异。所有市(县)早、晚稻全生育期均缺水,缺水量主要分布在拔节孕穗期和分蘖前期。近50年海南岛早、晚全生育期需水量和缺水量多数市(县)(占比为55.6%~66.7%)呈减少趋势且以不显著减少为主,对海南岛水稻种植总体有利。但海口市、东方市、临高县、白沙县、琼中县和定安县早稻全生育期缺水量,东方市、昌江县、白沙县、琼中县、定安县、琼海市、文昌市和乐东县晚稻全生育期缺水量在增加,需加强稻田用水管理。

海南岛三大流域“十三五”水质变化特征及“十四五”趋势预测

为服务海南自由贸易港水生态环境保护,基于海南省地表水环境质量监测网监测数据,对海南岛南渡江、昌化江、万泉河三大流域“十三五”期间水质状况、主要污染物浓度、综合污染指数变化进行了分析,采用Spearman秩相关系数研判其污染变化特征,并采用均值GM(1,1)模型(EGM)预测“十四五”期间水质变化趋势。结果表明:“十三五”期间,海南岛三大流域水质状况总体呈稳中向好趋势,南渡江、万泉河流域水质优良比例分别上升至96.3%、100%,昌化江流域水质优良比例保持在100%;三大流域CODMn、CODCr、氨氮、总磷浓度年均值均处于较低水平,低于GB 3838—2002《地表水环境质量标准》Ⅱ类标准限值,其中CODCr年均值均低于Ⅰ类标准限值,“十三五”期间除氨氮浓度下降外,其他指标均有不同程度的上升或波动,上升幅度为6.7%~23.8%;干流综合污染指数均小幅下降,下降幅度为0.03~0.04,主要支流综合污染指数自上游到下游呈波动上升的空间变化特征。EGM预测结果表明,“十四五”期间海南岛三大流域干流和绝大部分支流水质综合污染指数呈上升趋势,最大上升幅度达108.3%,三大流域水环境仍面临较大的压力,尤其是支流汇入带来的污染负荷不容忽视。“十四五”期间,应以系统保护思路,落实“六水共治”“一河一策”等措施,进一步改善三大流域水质。

基于碳储存变化的海岸带生态系统修复策略——以海南岛东南海岸带为例

碳达峰碳中和、国土空间生态修复、海域海岛可持续管理均是国家重大发展战略的重要内容。海南东南海岸带近年来因自然因素、人为干扰和全球气候变化的影响,生态系统破坏严重,碳汇功能明显下降。其生态质量的下降与海南自由贸易港和国家生态文明建设试验区的定位要求明显不符,基于碳储存的生态系统修复工作亟需开展。文章以海南岛东南海岸带为例,基于InVEST模型的碳储存模块,结合研究区2000、2010、2020年土地利用数据,估算研究区碳储量,划分“碳汇、碳源区”,评价其碳储存功能,识别近20年来研究区碳损失状况,明晰碳损失严重区域,划分生态修复功能区。结果表明:2000—2020年,研究区建设用地扩张明显,林草地面积削减;生态系统受到不同程度的破坏,碳储量持续下降,20年降低了0.11 Gt;碳储量低的区域沿着海岸带环线向内陆延伸,万宁市区域单位栅格碳密度值最低,三亚市区域单位栅格碳密度降低最多;碳源区面积始终大于碳汇区面积,碳储存功能为差和极差的区域面积分别为39.84和27.31 km^(2),主要分布于北部万宁市和乐镇、南部蜈支洲岛上方、西南部三亚市右侧等区域;基于碳损失和生态系统服务价值等级细分了自然修复区、人工辅助区、重建修复区和适度开发区,并针对性、差异化地提出包括退养还湿、岸线修复、湿地重建、加强监管等修复策略。

海南岛近岸海域鱼类群落结构研究

根据2006—2007年在海南岛近岸区进行了4个航次的底拖网调查资料,分析了海南岛近岸区的鱼类种类组成和群落特征。结果显示,海南岛近岸区鱼类丰富,共捕获283种,隶属于21目100科170属,暖水性种占83.4%,暖温性种类16.6%;与大西洋、印度洋和太平洋的共有种分别为12种、173种、283种,与黄渤海、东海、日本、菲律宾和印度尼西亚的共种分别为75种、217种、186种、131种和151种;相对资源量指数与相对资源密度指数的季节变化趋势相一致,最高值在夏季,最低值在冬季;优势种(IRI≥500)为发光鲷(Acropoma japonicum)、斑鳍天竺鱼(Apogonichthys carinatus)、黄斑鲾(Leiognathus bindus)、皮氏叫姑鱼(Johnius belengeri)、大头白姑鱼(Argyrosomus macrocephalus)、鯻(Therapon thraps)、棕斑腹刺魨(Gastrophysus spadiceus)和麦氏犀鳕(Bregmaceros macclellandi)。

海南西部近岸浮游植物的周年变化及主要关联因素

报道了2008—2009年4季度海南西部近岸浮游植物群落的周年动态并探讨其主要关联因素。165份样品经鉴定共有浮游植物4门74属155种(含5变型和2变种),周年平均丰度为(6.36±4.75)×103cells/L。硅藻在物种组成和丰度上均占绝对优势,其次为甲藻,蓝藻(束毛藻)在7月增殖。主要优势种为菱形海线藻(Thalassionema nitzschioides)、奇异棍形藻(Bacillaria paradoxa)、具槽帕拉藻(Paralia sulcata)、旋链角毛藻(Chaetoceros curvisetus)、笔尖根管藻(Rhizosolenia styliformis)、束毛藻(Trichodesmium spp.)、海洋原甲藻(Prorocentrum micans)等。物种组成的季节差异较大,10月浮游植物种类贫乏,1月次之,4月、7月最丰富。丰度10月最高,季节差异并不明显。束毛藻在4月、7月呈斑块状群聚分布。浮游植物周年平均丰度并不高(<1.0×104cells/L)。不同季节优势种有明显的交错和变化,菱形海线藻、奇异棍形藻、具槽帕拉藻为全年优势种。浮游植物物种多样性指数和均匀度都表现出较高的值,均匀度与多样性指数的季节变化特点基本一致,群落多样性高的季节物种均匀度也好。物种多样性指数指示调查区水体遭受污染程度低,水质状况优。调查区各季节的浮游植物丰度与温度之间无显著的相关关系,1月丰度与盐度则呈密切负相关关系。10月浮游植物丰度与无机氮(DIN)呈密切的正相关关系。7月浮游植物丰度与活性磷酸盐(PO4-P)呈密切的负相关关系。浮游动物对浮游植物的摄食压力直接影响到后者的丰度变动,并伴随着海区生态系统的相关复杂现象及生物学过程的作用。

海南岛东南部海湾350年古风暴事件沉积与历史文献记录对比

本项研究试图从沉积记录中分析古风暴事件的时间序列。以海南岛东南部黎安潟湖和新村潟湖钻孔沉积物为研究对象,选取沉积物粒度、有机质和碳酸盐含量等参数建立台风事件的鉴别指标,同时利用放射性核素210Pb计年确定沉积物柱状样的年代序列,对海南岛东南部的古风暴活动进行了分析。结果显示,柱状岩心的粒度指标、有机质和碳酸盐含量清晰地记录了海南省东南部过去350年期间的35次特大风暴潮事件,与历史文献资料对比良好。基于历史文献和沉积记录的风暴潮事件恢复了近350年来的风暴活动历史,发现海南省东南部特大风暴事件频数与厄尔尼诺强度有显著关系,同时还可能受到太平洋涛动和太阳黑子活动等多种因素的综合影响。恢复海岸带地区长时间尺度高分辨率的古风暴记录,为探讨全新世以来古风暴活动的气候响应机制提供了有效信息。

海南岛近岸海域鱼类物种组成和多样性的季节变动

根据2006年～2007年间在海南岛近岸海域进行的4个航次底拖网调查资料,分析了该海域鱼类物种组成和生物多样性特征。发现该海域鱼类种类较为丰富,调查共采集到鱼类292种,隶属于21目100科172属;其中暖水性种类数占83.32%,暖温性种类数占16.78%;与中国黄渤海共有种76种,与东海共有种220种,与南海大陆架、大陆坡和南海诸岛海域共有种分别为279种、42种和51种。鱼类优势种[相对重要性指数(IRI)>500]依次为发光鲷(Acropoma japonicum)、斑鳍天竺鱼(Apogonichthys carinatus)、黄斑鲾(Leiognathus bindus)、皮氏叫姑鱼(Johnius belengeri)、大头白姑鱼(Argyrosomus macrocephalus)、(Therapon theraps)、棕斑腹刺鲀(Gas-trophysus spadiceus)和麦氏犀鳕(Bregmaceros macclellandi)。以生物量为基础采用5个指数研究了该海域鱼类多样性现状,并采用季节更替指数(AI)和迁移指数(MI)对各季节鱼类群落的稳定性进行了分析。结果显示,该海域鱼类多样性水平较高,相邻季节的鱼类物种相似性也较高,随着鱼类的洄游,群落的稳定性出现较大波动。