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1.
珊瑚藻是珊瑚礁生态系统中重要的功能性群体。2010年通过水肺潜水分析了三亚珊瑚礁区的珊瑚藻种类组成和丰度, 以及群落空间特征与环境因子的关系。共鉴定出3科10属25种珊瑚藻, 其中珊瑚藻科占优势地位。三亚珊瑚礁区的珊瑚藻优势种分别为叉节藻Amphiroa ephedraea、拟中叶藻Mesophyllum simulans、串胞新角石藻Neogoniolithon fosliei、中叶藻M. mesomorphum、圆锥呼叶藻Pneophyllum conicum、孔石藻Porolithon onkodes和布氏水石藻Hydrolithon boergesenii。基于多元统计的分析结果, 将调查采样站位分为近岸型和离岸型2个主要集群, 其中近岸型的珊瑚藻种类以浊度、沉积速率(0~63μm)和悬浮物耐受种类为主, 离岸型则以光依赖-沉积物敏感种类为主。以珊瑚藻种类组成和丰度为基础的群落相似性分析结果表明, 其空间变异处于显著性水平。生物与非生物变量的相关分析结果表明, 最佳两变量组合(浊度和盐度)显著影响三亚珊瑚礁区2种类型调查站位中的珊瑚藻集合。在同一个研究站位, 因受干扰程度不同, 深水处的珊瑚藻的覆盖率比浅水处高。分析结果表明, 在三亚独特的珊瑚礁区中, 自然或人为的物理干扰因素都对调节珊瑚藻群落结构非常重要。  相似文献   

2.
Late Quaternary coral reefs have developed on the southwestern Australian margin, which has otherwise been characterised by cool-water carbonates since the Eocene. The Houtman Abrolhos coral reefs are at the limits of existence, extending, with the assistance of the Leeuwin Current, a poleward-flowing, warm water stream, into a region dominated by more temperate communities. Coring in the Easter Group reefs, supported by high precision dating, by both U/Th TIMS and 14C methods, has shown vigorous coral growth, with reefs over 26 m thick in the Holocene and over 15 m thick in the Last Interglacial. Each of the three Abrolhos platforms consists of a central platform composed of Last Interglacial reefs, about which windward and leeward Holocene reefs developed asymmetrically. Reef, peritidal and eolian facies comprise the emergent Last Interglacial limestones which are extensively calcretized, with reef facies up to 5 m above MSL. The Last Interglacial high stand lasted for at least 10 ka from 130 to 120 ka, and possibly 15 ka, from 132 to 117 ka. Holocene reef facies are also emergent by 0.5 m, and are overlain by peritidal and storm ridge facies in an upward-shallowing sequence. Windward (10 m thick) and leeward (26 m thick) Holocene reefs in the Easter Group show contrasting lithofacies. The wave-exposed windward reefs consist of a slow-growing association of coralline algal bindstones and coral framestones, whereas fast-growing coral framestones dominate the more protected leeward reefs. The leeward reefs commenced growth 10,000 years ago and grew to the present sea level by 6500 years ago, generating Holocene constructional topography consisting of ‘blue-hole’ terrain in the leeward parts of the platforms.  相似文献   

3.
On the rocky coasts of the northwestern Mediterranean basin, biogenic littoral rims built by the coralline rhodophyte Lithophyllum lichenoides develop, whose remains may be preserved for millennia when submerged in a rising sea environment. These remains can be used as biological indicators of recent sea-level variations. Our survey of the continental coasts of Var and Bouches du Rhône, west of Marseilles (southern France) and of northern Corsica shows that relative sea level rose about 1.6 m in the study area during the last 4500 years without exceeding the present datum. The rate of sea-level rise was 0.4 mm per year between 4500 and 1500 yr B.P. and slowed down to 0.2 mm per year from 1500 yr B.P. to present time. There are also morphological indications of an acceleration of the rate of sea-level rise during the last century, supporting the evidence of tide gauges. Regions at the periphery of the above zone (Alpes Maritimes, Italian border zone, and the French and Spanish Catalonia regions) were also surveyed, but a weaker development of Lithophyllum rims and bad preservation of algal remains led to unconvincing dates which could also be linked to regional tectonic trends.  相似文献   

4.
Marine hydrogenetically precipitated ferromanganese crusts are widespread in the Pacific Ocean. They occur as pavements coating volcanic or sedimentary hard-rock substrates, mainly on the slopes of seamounts, plateaus and hills in ocean basins and continental margins. We studied three ferromanganese crusts from one dredge haul from the Rivera Plate (western margin of Mexico), which are up to 15 mm thick and grow directly on a substrate of pillow basalt fragments. They consist of laminated, botryoidal, porous aggregates mostly of Fe and Mn oxyhydroxides and up to 10% silicates. XRD analysis showed the predominance of poorly crystallized mineral phases in the crusts that include Mn-feroxyhyte and vernadite, and an authigenic smectite-like clay. Detrital minerals probably derive from granodiorites of the eastern wall of the neighboring Middle America Trench. Scattered barite grains occur on the crust surface and suggest plume fall-out derived from hydrothermal vents, although a possible pelagic source cannot be dismissed. Ratios between major (Fe, Mn, Si) and trace (Co, Ni, Cu) elements reveal that such crusts are predominantly hydrogenetic in origin, although they show a hydrothermal influence that increases in the outer layers. Iron contents range from 16.2 to 25.2 wt.%, and manganese from 3.4 to 14.5 wt.%. The Fe/Mn ratio ranges from 1.6 to 7.0. The SiO2/Al2O3 ratio ranges from 4.3 to 6.6, indicating the presence of biogenic silica (radiolarians). The concentrations of copper (up to 383 ppm) and cobalt (up to 534 ppm) are significantly below those of the typical hydrogenetic crusts, whereas Ni (up to 1320 ppm) is about the same or slightly lower. REE normalized profiles and ΣREE values (486 to 732 ppm) match those reported for hydrogenetic crusts, but suggest a hydrothermal contribution for the later crust layers. The inferred crust growth rates using the Co-chronometer (44 and 229 mm/Myr) are higher than those reported for pure hydrogenetic crusts (mostly 1 to 6 mm/Myr), thus indicating an increasing hydrothermal influence. The highest growth rate (229 mm/Myr, corresponding to the outer crust layers) suggests a regional hydrothermal input of iron and manganese to seawater. The intensification of regional submarine hydrothermal activity began about 13,000 yr ago, and may be related to the tectonic activity in the complex junction of the Rivera, Cocos, Pacific and North America plates.  相似文献   

5.
Multibeam sonar mapping, drill cores and underwater video data have confirmed the existence of a previously unknown coral reef province in the Gulf of Carpentaria, Australia. Seven reefs, comprised of coral limestone that support living corals have been mapped so far and as many as 50 other reefs may exist in the region. U/Th ages show that reef growth commenced shortly after limestone pedestals were submerged by rising sea level around 10.5 kyr BP, making them the oldest Holocene reefs known in Australia. Reef growth persisted for ~ 2.0 kyr but it had ceased at most locations by ~ 7.0 kyr BP. Measurements of reef growth rates (0.95 to 4 m kyr− 1), indicate that the reefs were unable to keep pace with contemporaneous rapid sea level rise (> 10 m kyr− 1), which is consistent with a “give up” reef growth history. Core samples from reef platforms demonstrate that Pleistocene limestone is exposed at depths of 27 and 30 m below present mean sea level. These depths represent regionally significant phases of reef growth during a prolonged sea level still stand. We conclude that the reefs are therefore mostly relict features, whose major phase of growth and development relates to an earlier, pre-Holocene sea level still stand.  相似文献   

6.
The widespread occurrence of microbialites in the last deglacial reef frameworks (16–6 Ka BP) implies that the accurate study of their development patterns is of prime importance to unravel the evolution of reef architecture through time and to reconstruct the reef response to sea-level variations and environmental changes.The present study is based on the sedimentological and chronological analysis (14C AMS dating) of drill cores obtained during the IODP Expedition #310 “Tahiti Sea Level” on the successive terraces which typify the modern reef slopes from Tahiti. It provides a comprehensive data base to investigate the microbialite growth patterns (i.e. growth rates and habitats), to analyze their roles in reef frameworks and to reconstruct the evolution of the reef framework architecture during sea-level rise.The last deglacial reefs from Tahiti are composed of two distinctive biological communities: (1) the coralgal communities including seven assemblages characterized by various growth forms (branching, robust branching, massive, tabular and encrusting) that form the initial frameworks and (2) the microbial communities developed in the primary cavities of those frameworks, a few meters (1.5 to 6 m) below the living coral reef surface, where they heavily encrusted the coralgal assemblages to form microbialite crusts. The dating results demonstrate the occurrence of two distinctive generations of microbialites: the “reefal microbialites” which developed a few hundred years after coralgal communities in shallow-water environments, whereas the “slope microbialites” grew a few thousands of years later in significantly deeper water conditions after the demise of coralgal communities.The development of microbialites was controlled by the volume and the shape of the primary cavities of the initial reef frameworks determined by the morphology and the packing of coral colonies. The most widespread microbialite development occurred in frameworks dominated by branching, thin encrusting, tabular and robust branching coral colonies which built loose and open frameworks typified by a high porosity (> 50%). In contrast, their growth was minimal in compact coral frameworks formed by massive and thick encrusting corals where primary cavities yielded a low porosity (~ 30%) and could not host a significant microbialite expansion.  相似文献   

7.
Seafloor blister-like mounds, methane migration and gas hydrate formation were investigated through detailed seafloor surveys in Santa Monica Basin, offshore of Los Angeles, California. Two distinct deep-water (≥ 800 m water depth) topographic mounds were surveyed using an autonomous underwater vehicle (carrying a multibeam sonar and a chirp sub-bottom profiler) and one of these was explored with the remotely operated vehicle Tiburon. The mounds are > 10 m high and > 100 m wide dome-shaped bathymetric features. These mounds protrude from crests of broad anticlines (~ 20 m high and 1 to 3 km long) formed within latest Quaternary-aged seafloor sediment associated with compression between lateral offsets in regional faults. No allochthonous sediments were observed on the mounds, except slumped material off the steep slopes of the mounds. Continuous streams of methane gas bubbles emanate from the crest of the northeastern mound, and extensive methane-derived authigenic carbonate pavements and chemosynthetic communities mantle the mound surface. The large local vertical displacements needed to produce these mounds suggests a corresponding net mass accumulation has occurred within the immediate subsurface. Formation and accumulation of pure gas hydrate lenses in the subsurface is proposed as a mechanism to blister the seafloor and form these mounds.  相似文献   

8.
珊瑚岸礁破碎带附近波浪演化实验研究   总被引：4，自引：1，他引：3  
通过波浪水槽实验对珊瑚岸礁破碎带附近波浪演变规律开展研究,实验采用了概化的岸礁模型,测试了4种礁坪水深、4种礁前斜坡坡度和一系列入射波高的组合工况。对破碎带宽度和破碎带附近波浪的入射、反射、透射以及能量耗散进行了测量分析,透射波的计算考虑了礁坪上高次谐波的影响。结果表明:礁坪水深和入射深水波高的比值(即礁坪相对水深)是影响岸礁破碎带附近波浪演化的关键参数,而礁前斜坡坡度的影响在本文测量的范围内可以忽略不计。破碎带宽度与礁坪上浅水波波长为同一数量级,并与礁坪相对水深成反比;透射系数随礁坪相对水深的增大呈线性增长,而反射系数的变化却无类似规律;岸礁能够削弱超过50%入射波能,礁坪相对水深越小,波浪破碎造成的能量耗散越大。  相似文献   

9.
《Marine Geology》2006,225(1-4):223-246
We present detailed bathymetry, remotely operated vehicle (ROV) and submersible observations, and sedimentary and radiocarbon age data from carbonate deposits recovered from two submerged terraces at − 150 m (T1) and − 230 m (T2) off Lanai, Hawaii. The tops of the terraces are veneered by relatively thin (< 5 m) in situ accumulations of coralline algal nodule, coralgal nodule, Halimeda and a derived oolitic facies deposited in intermediate (30–60 m) to deep fore-reef slope settings (60–120 m). The data are used to develop a sedimentary facies model that is consistent with eustatic sea-level variations over the last 30 ka. Both nodule facies on T1 and T2 initiated growth 30–29 ka following a fall in sea level of ∼50 m and increase in bottom currents during the transition from Marine Isotope Stage 3 to 2. The nodules accreted slowly throughout the Last Glacial Maximum when sea-level was relatively stable. Drowning occurred during the early deglaciation (17–16 ka) and was marked by the complete drowning of coralline algal nodules facies on T2 and incipient drowning of coralgal facies on T1. Abrupt sea-level rise during the middle deglaciation, perhaps associated with global meltwater pulse 1A (14–15 ka), finally drowned the coralgal facies on T1, which in turn was overlain by a deep-water Halimeda facies or an oolitic facies derived from upslope. Our data indicates that Lanai has experienced relatively little vertical tectonic movement over the last 30 ka. Using paleobathymetric data derived from the sedimentary facies, age vs. depth relationships, and published sea-level curves, we estimate that Lanai could be either slowly uplifting or subsiding, but at rates < 0.1 m/kyr (uplift) or < 0.4 m/kyr (subsidence) over this 30 kyr period.  相似文献   

10.
采用硅胶柱层析色谱法、中压正相柱层析色谱法、中压反相柱层析色谱法以及半制备高效液相色谱法对中国南海软珊瑚来源真菌Acremonium sp. SCSIO41216的大米发酵产物进行分离纯化, 并使用核磁共振、质谱等波谱学方法, 结合其理化性质及文献数据鉴定了7个单体化合物结构: fischexanthone(1)、sydowinin A (2)、(22E)-5α,8α-epidioxyergosta-6,22-dien-3β-ol (3)、16-O-去乙酰基夫西地酸内酯(4)、环-(S)-脯氨酸-(R)-亮氨酸(5)、环-(S)-脯氨酸-8-羟基-(R)-异亮氨酸(6)和环(L)-脯氨酸-(L)-苯丙氨酸(7)。化合物1—7均首次从海洋软珊瑚来源的枝顶孢属真菌(Acremonium sp.)中分离获得。  相似文献   

11.
Much of coral reef ecology has focused on how human impacts change coral reefs to macroalgal reefs. However, macroalgae may not always be a good indicator of reef decline, especially on reefs with significant sea urchin populations, as found in Kenya and Hawaii. This study tests the effects of trophic interactions (i.e. herbivory by fishes and sea urchins) and spatial competition (between algae and coral) on algal community structure of reefs surrounding two Hawaiian Islands that vary in their level of human impacts. Reef‐building organisms (corals and crustose coralline algae) were less abundant and turf algae were more abundant on Maui as compared to Lanai, where human impacts are lower. In contrast to previous studies, we found no evidence that macroalgae increased with human impacts. Instead, low turf and macroalgal abundance were best explained by the interactive effects of coral cover and sea urchin abundance. Fishing sea urchin predators appeared to have cascading effects on the benthic community. The absence of sea urchin predators and high sea urchin densities correspond to a disproportionately high abundance of turf and crustose coralline algae. We propose that high turf algal abundance is a better indicator of reef decline in Hawaii than high macroalgal abundance because turf abundance was highest on reefs with low coral cover and few fish. The results of this study emphasize that understanding changes in community composition are context‐dependent and that not all degraded reefs look the same.  相似文献   

12.
Deep-water benthic algal composition and cover were studied with a submersible on the deep fore reef of Lee Stocking Island, Bahamas, from 45 to 150 m. Algal cover decreased from 57% to 16% over this depth range. Although there was substantial overlap in depth distributions, different species or groups of species dominated benthic cover at different depths. Lobophora and Halimeda copiosa co-dominated the fore reef from 45 to 60 m. A Corallinales/Peyssonnelia group was abundant from 60 to 120 m. The Corallinales/Peyssonnelia group shared dominance with Ostreobium between 90 and 120 m. Ostreobium was the only alga observed below 150 m and remained abundant below 200 m. Movement of sand down the fore reef is recognized as having substantial influence on algal cover.  相似文献   

13.
Significant synchronous shifts in the chemistry, mineralogy, grain sizes and color of the sediments at 6 m below sea floor (mbsf) at ODP Site 1195 on the Marion Plateau (NE Australia) are interpreted to reflect a major regional paleoceanographic change: the initiation of the southern province of the Great Barrier Reef (GBR). The onset of this massive carbonate production centre nearby resulted primarily in increased deposition of carbonate-rich sediments of neritic origin. Both sedimentation rate and terrigenous input record a coincident decline attributed to inshore trapping of materials behind the reefs. Our best estimate places the development of reef framework in the southern part of the GBR between 560 and 670 kyr B.P., based on an age model combining magnetostratigraphic and biostratigraphic data. The proposed estimation agrees with previous studies reporting an age between 500 and 930 kyr B.P., constraining more tightly their results. However, it does not support research placing the birth of the GBR in Marine Isotope Stage (MIS) 11 ( 400 kyr), nor the theory of a worldwide modern barrier reef development at that time.  相似文献   

14.
Halimeda is one of the major reef-building algas in the middle Miocene of Xisha, and one of the significant reefbuilding algas in the algal reef oil and gas field of the South China Sea. However, there have been few reports regarding the characteristics of mineral rocks, reservoir porosity and permeability layers, and sedimentationdiagenetic-evolution of fossil Halimeda systems. The present paper briefly introduces the relevant studies on chlorophyta Halimeda and the research status of oil and gas exploration. Through the 1 043 m core of the Xichen-1 well, we studied the characteristics of the mineral rocks and porosity and permeability of the middle Miocene Halimeda of the Yongle Atoll, identified and described the segments of fossil Halimeda, and pointed out that most of the segment slides are vertical sections in ovular, irregular or long strips. The overwhelming majority of these fossil Halimeda found and studied are vertical sections instead of cross sections. In this paper, knowledge regarding the cross sections of fossil Halimeda is reported and proven to be similar with the microscopic characteristics of modern living Halimeda; fossil Halimeda are buried in superposition; it is shown that there are different structures present, including typical bio-segment structure, and due to its feature of coexisting with red alga, tying structure, twining structure and encrusting structure are all present; and finally, it is suggested to classify the fossil Halimeda into segment algal reef dolomites. In addition, all of the studied intervals are moderately dolomitized. Secondary microcrystalline-dolosparite dominates the original aragonite raphide zones,and aphanitic-micrite dolomite plays the leading role in the cortexes and medullas; in the aragonite raphide zones between medulla and cysts, secondary dissolved pores and intercrystalline pores are formed inside the segments, and algal frame holes are formed between segments; therefore, a pore space network system(dissolved pores + intragranular dissolved pores—intercrystalline pores + algal frame holes) is established. Segment Halimeda dolomite has a porosity of 16.2%–46.1%, a permeability of 0.203×10–3–2 641×10–3 μm2, and a throatradius of 23.42–90.43 μm, therefore it is shown to be a good oil and gas reservoir. For the reasons mentioned above, we suggest building the neogene organic reef-modern reef sedimentation-diagenetic-evolution models for the Xisha Islands.  相似文献   

15.
High-resolution, seismic-reflection data elucidate the late Quaternary development of the largest coral-reef complex in the main Hawaiian Islands. Six acoustic facies were identified from reflection characteristics and lithosome geometry. An extensive, buried platform with uniformly low relief was traced beneath fore-reef and marginal shelf environments. This highly reflective surface dips gently seaward to ~130 m depth and locally crops out on the seafloor. It probably represents a wave-cut platform or ancient reef flat. We propose alternative evolutionary models, in which sea-level changes have modulated the development of reef systems, to explain the observed stratigraphic relationships. The primary difference between the models is the origin of the underlying antecedent surface, which arguably could have formed during either regression/lowstand or subsequent transgression.  相似文献   

16.
Lakes can be used as model basins to investigate subaqueous slope stability under static and dynamic loading conditions. This study combines geophysical, sedimentological and in situ geotechnical methods with limit equilibrium calculations in order to discuss (i) the geological and sedimentological processes acting on submerged non-deltaic lateral slopes in perialpine, fjord-type Lake Lucerne (Central Switzerland); (ii) their control on physical and geotechnical properties that eventually affect the subaqueous stability conditions and slope failure initiation, and (iii) the quantitative assessment of subaqueous slope stability. Three detailed case studies are presented to describe and quantitatively reconstruct stability conditions of slopes that failed during a well-documented historic earthquake in 1601 A.D. and during a prehistoric Late Holocene earthquake around 2220 cal yr BP (both Mw > 6).

Glacio-lacustrine sedimentation dominated by suspension settling from meltwater plumes and slight overconsolidation from ice-grounding during small readvances of a generally retreating glacier lead to a peculiar glacial-to-postglacial lithologic slope succession that eventually was buried by the Holocene sediment drape. During past earthquake shaking, the slopes that were stable under static loading conditions (factor of safety of 1.5–2) failed along planar sliding surfaces that developed at the lithological boundary between fine-grained, thinly-laminated, slightly underconsolidated cyclic plume deposits with low undrained shear strength values above and overconsolidated, glacially-deformed, glacio-lacustrine deposits with excessive formation pore pressure below. Measured in situ shear strength characteristics and sediment geometries were implemented into limit equilibrium models that allow for quantitative reconstruction of critical ground accelerations of past earthquakes in Central Switzerland. Results reveal seismic peak ground acceleration (PGA) of  0.08 g and  0.14 g for the historic 1601 A.D. Mw  6.2 earthquake and the prehistoric,  2220 cal yr B.P. earthquake, respectively. Additionally, results reveal that stability conditions change over relative short geological time scales because the postglacial sedimentation rate, which mainly controls the static weight of the slope sediment acting on the critical lithological boundary, turns out to be a key parameter in “charging” slopes susceptible to sliding.  相似文献   


17.
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18.
During the late summer monsoon living planktonic foraminifera were collected in the southeastern Arabian Sea between 3°N and 15°N by using six vertical plankton tows. Sixteen species of planktonic foraminifera were identified. Among them, Globigerinoides ruber and Globigerinoides sacculifer are the most abundant species, while the ecologically most important species Globigerina bulloides is very rare. The low abundance of G. bulloides can be explained by the warming of the surface water in combination with deepening of the mixed layer, since this species preferentially dwells in nutrient-rich upwelling waters. The population density of planktonic foraminifera ranges between 31 and 185 specimens per 10−3 m3. The low absolute numbers of planktonic foraminifera are similar to the numbers which were reported before from the non-upwelling areas in the Arabian Sea. The low absolute numbers and the collected foraminiferal assemblages are therefore highly indicative of the Arabian Sea non-upwelling areas. Particularly significant are the low absolute and relative numbers of the non-spinose species Globorotalia menardii and Neogloboquadrina dutertrei. The absence of these species indicate the relatively low nutrient levels in this area at the tail end of the summer monsoon period.  相似文献   

19.
大管岛礁区潮下带大型底栖海藻群落的初步研究   总被引：2，自引：0，他引：2  
1990年5月和11月对大管岛礁区潮下带大型底栖海藻进行了两次定量调查。共采到23种大型海藻，其群落构成以红藻类占优。海藻种类的区系温度性质属明显的温水性区系。5月份平均生物量为240．939／m2，11月份平均生物量为164．399／m2。两季度月都以岛西侧的D7断面平均生物量最高，分别为820．159／m2和472．509／m2。就垂直分布而言，1—2米水层内海藻分布密度最高，达527．549／m2。优势种为海蒿子和石花菜。  相似文献   

20.
南海永乐龙洞位于西沙群岛永乐环礁,是迄今为止发现的最深的海洋蓝洞,水文环境及理化因素特殊,90 m以下水体为无氧环境。为研究永乐龙洞浮游植物的群落组成及其昼夜变化,于2017年3月在龙洞、潟湖及外礁坡进行浮游植物样品采集。研究结果表明:龙洞内叶绿素a浓度呈现随深度先增大后减小的趋势,日间浓度最大值层出现在40 m层(0.42μg/L),夜间则出现在20 m层(0.59μg/L)。永乐龙洞微微型浮游植物丰度介于1.1×10^3~5.1×10^4 cells/mL。聚球藻在上层水体占优势(0~20 m),40 m以下水层原绿球藻丰度对微微型浮游植物丰度贡献率最大(90%以上),微微型真核浮游植物丰度在整个水体都较低(除20 m层)。微微型浮游植物昼夜存在明显差异,夜间其丰度最大值层为20 m层,日间则上移至表层。本研究共记录微型和小型浮游植物5门41属55种(含未定种)。其中,硅藻门25属34种、甲藻门12属15种、金藻门1属1种、蓝藻3属、隐藻1属。微型和小型浮游植物丰度介于3.3×10^2~9.8×10^4 cells/L。甲藻丰度对浮游植物总丰度贡献率最大,其次是硅藻,隐藻和蓝藻丰度仅在少数水层占优势。微型和小型浮游植物昼夜变化明显,夜间丰度最大值层为20 m层,日间则出现在40 m层。微微型、微型和小型浮游植物垂直分布与叶绿素a浓度垂直分布一致性高。龙洞浮游植物的种类数和丰度高于潟湖和外礁坡。  相似文献   

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