不同受损情况下珊瑚礁海岸动力地貌差异性分析

探索珊瑚礁与海滩地貌之间动力地貌联系是认识珊瑚礁海岸变化的重要一环.本文以雷州半岛徐闻西落港珊瑚礁海岸为研究对象,应用RTK-GPS和无人船开展岸滩剖面和近岸水下地形的测量、结合海滩沉积物分析,基于FUNWAVE-TVD数值模型模拟并分析不同珊瑚礁地形地貌条件下波浪动力传播过程.结果显示,研究区珊瑚礁水下地形是影响礁后...     

Sedimentary facies of the eastern Pacific's northernmost reef-like setting (Cabo Pulmo,Mexico)

Cabo Pulmo, Mexico, is often cited as the eastern Pacific's northernmost coral reef. We investigated sedimentary dynamics to verify whether the system functions sedimentologically as a reef, which would mean that it retained internal sediment in a framework and exported peri-reefal sediment creating clearly identifiable facies dominated by reefal fauna. We mapped distribution of sediments using grab samples, the acoustic ground-discrimination systems QTC View and Echoplus at 50 kHz signal frequency and an IKONOS satellite image. Morphologically, the bay of Cabo Pulmo can be divided into intrusive dikes and rocky hardgrounds in less than 10 m depth and a sandy interior with rocky outcrops sloping to over 40 m. Reefal fauna without lasting framework-building but with production of typically reef-associated carbonate sediments, as well as a patch-reef facies were found on the dikes and hardgrounds. Sediments in the bay were a mixture of carbonates and siliciclastics and were influenced by a seasonal river near the bay's center that imported siliciclastic material. To the north and south sediments had a higher carbonate content, although overall the bay was characterized by > 50% siliciclastics. The shallower subtidal sands were dominated by mollusk fragments, whereas in depths > 30 m planktonic foraminiferal sand was found. Acoustically and optically remote-sensed maps were used to differentiate between the rocky and sandy areas and to identify the presumed off-shelf transport pathway of reef-derived carbonates. Overall, the sedimentary system is characterized by carbonate production, but the coarser reef derived carbonates (coral and reef-dwelling mollusks) are transported off-shelf along a steep depth gradient and little typical peri-reef sediment remains. This transport is likely aided by storms. Since no sediment retaining frameworks are formed, the dikes cannot retain internal sediment, and the reefal fauna was not dominant in sediments throughout the bay, we conclude that Cabo Pulmo sedimentologically functions only in a limited way like a coral reef.     

The relative importance of chlorophyll,dissolved and particulate material,and seawater to the vertical extinction of light

The attenuation of light by chlorophyll, particulate and dissolved material, and seawater off the coast of north-west Africa showed distinct cross-shelf variations. Attenuation was most rapid nearshore because of absorption by non-biological particles. This particulate matter was probably aeolian material from the nearby Sahara Desert of resuspended sand from the sediment. Regardless of the source, the marked light extinction resulted in decreased phytoplankton growth nearshore. Light attenuation characteristics of the region were anomalous when compared to those of other ocenic regimes.     

海滩-珊瑚礁系统风暴响应特征研究——以1409号台风“威马逊”对清澜港海岸影响为例

珊瑚礁海岸在我国热带地区广泛发育,海滩-珊瑚礁海岸的动力地貌过程是认识该类海岸的关键。本文基于对海南铜鼓岭-高隆湾岸段的台风"威马逊"前后跟踪观测,讨论了海滩风暴响应特征及其与珊瑚礁发育之间的联系。结果表明该岸段海滩在"威马逊"风暴作用下响应最为剧烈的区带位于平均海平面(MSL)以上,表现为后滨冲越,以及岸线蚀退、滩肩变窄、滩面侵蚀等响应特征。海滩风暴响应特征与近岸珊瑚礁发育密切相关,在无珊瑚或珊瑚受损的岸段海滩响应剧烈,剖面平均变化率(MPC)为其他岸段的3~6倍,珊瑚礁通过消耗波能对相邻海滩提供良好保护。海滩-珊瑚礁系统对风暴的响应特征受控于珊瑚礁对海岸波浪的消耗能力和海滩固有的缓冲能力。基于本文研究结果,归纳出风暴极端动力条件下海滩-珊瑚礁海岸的4种风暴响应模式。     

Diurnal variability in turbidity and coral fluorescence on a fringing reef flat: Southern Molokai,Hawaii

Terrigenous sediment in the nearshore environment can pose both acute and chronic stresses to coral reefs. The reef flat off southern Molokai, Hawaii, typically experiences daily turbidity events, in which trade winds and tides combine to resuspend terrigenous sediment and transport it alongshore. These chronic turbidity events could play a role in restricting coral distribution on the reef flat by reducing the light available for photosynthesis. This study describes the effects of these turbidity events on the Hawaiian reef coral Montipora capitata using in situ diurnal measurements of turbidity, light levels, and chlorophyll fluorescence yield via pulse-amplitude-modulated (PAM) fluorometry. Average surface irradiance was similar in the morning and the afternoon, while increased afternoon turbidity resulted in lower subsurface irradiance, higher fluorescence yield (ΔF/F_m^′), and lower relative electron transport rates (rETR). Model calculations based on observed light extinction coeffecients suggest that in the absence of turbidity events, afternoon subsurface irradiances would be 1.43 times higher than observed, resulting in rETR for M. capitata that are 1.40 times higher.     

Water column distribution of phospholipid-derived fatty acids of marine microorganisms in the Humboldt Current system off northern Chile

Suspended particulate matter samples from the oxygenated surface zone, the oxygen minimum zone, and the oxygenated deeper zone were collected from the upwelling area off Antofagasta in northern Chile during austral autumn (April 2001) to study the composition of microbial phospholipid-derived fatty acid methyl esters, using capillary gas chromatography-mass spectrometry. Whereas phytoplanktonic carbon dominated living organic matter near the coast, bacterial carbon was most abundant offshore. The biomarker distribution showed some differences between the depth levels sampled, such as the highest microbial abundance in the epipelagic zone represented by phytoplankton, especially diatoms, and a homogeneous distribution of bacterial biomarkers, with no indication of vertical segregation of functional groups as previously thought.     

Nature and composition of shore-zone sediments between Jeddah and Yanbu, eastern Red Sea

The shore-zone sediments between Jeddah and Yanbu, west coast of Saudi Arabia, are composed mostly of skeletal carbonate sands. The nearshore sediments containing benthic foraminifera, algal fragments and molluscs are multimodal, the mean grain size varying between 0.76 and 2.35 ø. The beach sediments, except samples dominated by cerithid gastropods in some localities, are relatively finer than the nearshore sediments. Although the beaches to a great extent comprise sand-sized material, fine lime muds and coarse clastic gravels occur in certain areas. The dune sediments comprising mostly algal grains and ooids are very fine with 50 percent of the material in the 0.25–0.18 mm size grade. Except a general northward decrease in mean grain size, regional trends in the textural parameters of the sediments between Jeddah and Yanbu are not quite apparent. Lateral variations in the textural characteristics suggest a landward migration of the sediments in the shore zone under the influence of northerly and northwesterly winds. The carbon and oxygen (δ ¹³C + 4.80 to 4.84‰ PDB) (δ ¹³O − 0.04 to + 0.53‰ PDB) isotopic ratios of the lime muds occurring in certain shallow margins in the shore-zone, which are much higher than those of the green algae, indicate that the fine carbonates are at least in part inorganic in origin.

Like the shallow-water carbonates in tropical seas, aragonite and high Mg-calcite are the dominant carbonate minerals in the shore-zone sediments. There is a landward increase in aragonite contents caused by the landward migration of fine material from the nearshore. The dominant clay mineral in the nearshore sediments is kaolinite with subordinate swelling chlorite and little illite. Kaolinite is contributed by the coastal regions under the sub-tropical humid climate. Swelling chlorite is considered to have been formed in the nearshore by mechanical mixture of chlorite and montmorillonite derived from the metamorphic and igneous terrains of the Tertiary mountains bordering the coastal plain.     

台湾海峡南部夏季的颗粒有机碳

根据2004年夏季、2005年夏季和2006年夏季3个航次观测的颗粒有机碳(POC)数据,表层POC含量的分布表现出近岸高、远岸低的特点,表层和次表层POC含量的高值区出现在东山以东以及南澳附近上升流区。沿岸流较强的2005年和2006年航次具有相对丰富的总悬浮颗粒物(TSM)含量。浮游植物是该区POC的主要来源。各航次的POC含量与叶绿素a(Chl a)含量正相关,所有航次统计的Chl a/POC与Chl a呈正相关,上升流区Chl a/POC偏小,上升流较强的航次高Chl a区的Chl a/POC也偏小,反映了上升流与高营养转换效率浮游生物生态在空间和时间上的联系。根据Chl a/POC~Chl a关系图判断,台湾海峡南部海域1988年、1998年和2004年夏季航次的浮游生物营养转换效率受到相对抑制,而在上升流信号较强的2005年和2006年夏季航次,上升流区的浮游生物高营养转换效率状态得以强化。各航次的POC含量和Chl a/POC比值与TSM含量正相关,POC/TSM比值与TSM负相关,沿岸流带来的陆源悬浮颗粒物通量波动,并没明显干扰台湾海峡南部以海洋浮游生物生态主导的颗粒有机碳生物地球化学循环格局。     

Hydro-meteorological influences and multimodal suspended particle size distributions in the Belgian nearshore area (southern North Sea)

Suspended particulate matter (SPM) concentration and particle size distribution (PSD) were assessed in a coastal turbidity maximum area (southern North Sea) during a composite period of 37 days in January–April 2008. PSDs were measured with a LISST 100X and classified using entropy analysis in terms of subtidal alongshore flow. The PSDs during tide-dominated conditions showed distinct multimodal behaviour due to flocculation, revealing that the building blocks of flocs consist of primary particles (<3 μm) and flocculi (15 μm). Flocculi comprise clusters of clay minerals, whereas primary particles have various compositions (calcite, clays). The PSDs during storms with a NE-directed alongshore subtidal current (NE storms) are typically unimodal and characterised by mainly granular material (silt, sand) resuspended from the seabed. During storms with a SW-directed alongshore subtidal current (SW storms), by contrast, mainly flocculated material can be identified in the PSDs. The findings emphasise the importance of wind-induced advection, alongshore subtidal flow and highly concentrated mud suspensions (HCMSs) as regulating mechanisms of SPM concentration, as well as other SPM characteristics (cohesiveness or composition of mixed sediment particles) and size distribution in a high-turbidity area. The direction of subtidal alongshore flow during SW storm events results in an increase in cohesive SPM concentration, HCMS formation, and the armouring of sand; by contrast, there is a decrease in cohesive SPM concentration, no HCMS formation, and an increase in sand and silt in suspension during NE storms.     

How Episodic Coral Breakage Can Determine Community Structure: A South African Coral Reef Example

Abstract. Africa's southernmost coral reefs are situated in Natal Province, South Africa. The Natal coast is exposed to open Ocean swells and episodic storm swell conditions. Benthic communities on these reefs differentiated into three community types: shallow reefs (8–18 m) were dominated by alcyonacean corals and low-growing, massive Scleractinia; intermediate reefs (18–25 m) were dominated chiefly by branching and tabular Scleractinia of the genus Acropora (A. austera, A. clathrata); deep reefs were not dominated by corals but by sponges. Breakage and recovery experiments indicated that the difference in Acropora dominance between shallow and intermediate sites was caused by breakage in high swell conditions. Survival of experimentally produced A. austera fragments was significantly higher in intermediate than in shallow sites, where higher surge made re-attachment and regeneration unlikely. Also, colony morphology was adapted to differential surge conditions: colonies on the shallow reefs were smaller with shorter branches, while on intermediate reefs they were much bigger with long, widely spreading branches. Episodic breakage and low fragment survival due to high water-motion thus excluded branching corals from shallow reef sites.     

Major- and trace-element composition of suspended matter in the north-east gulf of Alaska: Relationships with major sources

Seasonal variations of the distributions and chemical compositions of suspended particulate matter in the north-east Gulf of Alaska were studied during 1975–1976. Selected samples were analyzed for total suspended matter by gravimetry; particulate C and N by dry combustion gas chromatography; and particulate Al, Si, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu and Zn by thin-film X-ray secondary emission spectrometry. The results showed that suspended material from the Copper River and the coastal streams which drain the Bering, Guyot, and Malaspina glaciers was carried westward along the coast and deposited in nearshore environments. However, near Kayak Island, significant quantities of suspended material of terrestrial origin were deflected to the south-west, past the edge of the outer shelf, by an anticyclonic gyre.The distribution patterns of the major and trace elements in the particulate matter and their elemental ratios with aluminum indicated that: K, Ti, Mn and Fe were primarily associated with aluminosilicate material and C and N with organic material in all samples; and Si, Ca, Cr, Ni, Cu and Zn were primarily associated with aluminosilicate material in near-shore surface and near-bottom samples and with organic material in offshore surface samples. Only C, N, Ca, Cú and Zn showed significant seasonal variations which appeared to be related to biological production of organic matter.     

Temporal dynamics and persistence of sponge assemblages in a Central Pacific atoll lagoon

Sponges are important components of coral reef fauna, although little is known of their temporal dynamics. Sponges dominate the lagoon system at Palmyra Atoll in the Central Pacific, which may not be its natural state. Here we examined the temporal variability and recruitment rates of these sponge assemblages to determine if they are stable and examined the evidence that a recent transition has occurred from a coral‐ to sponge‐dominated system. We found 24 sponge species in permanent quadrats in the lagoon between 2009 and 2011, and 11 species on our recruitment panels. The sponge assemblage composition and abundance did not vary significantly between years and appear stable. Many sponge recruits were found in both years that the panels were examined although higher rates were recorded in the second year of the study. While it seems very possible that a change to a sponge‐dominated lagoon is associated with declining environmental quality at Palmyra as a result of modifications over 70 years ago, without pre‐modification data on reef assemblage composition this remains speculative. Our observations of short‐term temporal stability in the sponge assemblages at Palmyra highlight the potential for sponge‐dominated reef states to be maintained in degraded reef environments that are seemingly unsuitable for coral survival.     

海南岛鹿回头珊瑚礁研究进展

前人在海南岛鹿回头珊瑚礁区所做的工作主要集中于以下三方面：(1)鹿回头珊瑚礁区地貌的粗略描述;(2)鹿回头珊瑚礁记录的古海平面研究：(3)鹿回头珊瑚礁记录的现代环境信息研究。通过野外实地考察,将鹿回头珊瑚礁分为8个生物地貌带：礁前斜坡活珊瑚带、礁缘砾石突起脊带、外礁坪带、中礁坪带、内礁坪带、海滩、沙堤、洼地,它们是全新世海平呵和气候环境变化的产物。关于本区珊瑚礁的研究,结合全球珊瑚礁与环境的研究来看,许多工作有待于展开和补充,大致可从以下4个方面进行深入研究：(1)珊瑚礁的生物地貌过程;(2)珊瑚及珊瑚礁的高分辨率环境记录;(3)珊瑚对海洋环境污染的记录：(4)珊瑚礁生态系统与社会、经济及人文系统的关系及其可持续发展。     

珊瑚礁的成岩作用:来自南海永兴岛珊瑚礁的原位地球化学研究

珊瑚礁的地球化学特征记录了其形成时周围海水的状况,能够反映古海洋、古气候和古环境变化;然而珊瑚礁形成过程中及其形成后,容易受到成岩作用的影响,导致其矿物组成和地球化学特征发生变化;因此,在对珊瑚礁的研究中,首先要识别出保存原始沉积特征的组分,并排除后期成岩改造的影响.以西沙群岛永兴岛的SSZK1珊瑚礁钻孔岩心为研究对象...     

热带风暴过程中珊瑚礁坪示踪砂运移的现场实验研究

１９９５年１０月在小东海珊瑚礁海岸的礁坪上进行了示踪砂运动的现场实验。本次实验对浪,流以及示踪砂采样作了同步观测。根据所获的实验数据,分析在９５１６号热带风暴天气过程礁坪上示踪砂运移的基本规律。在一级近似下,测定并计算了泥沙在波生流作用下的漂移速度与流速比因子０．００２,混合深度小于２ｃｍ。这一结果与其它已往结果相比明显小得多。     

基于Ecopath模型的七连屿礁栖性生物的生态承载力分析

生态承载力评估是开展生物资源增殖放流, 维持珊瑚礁生态系统健康的基础和前提。本文基于2019年渔业资源和生态环境的综合调查数据, 构建了七连屿珊瑚礁海域生态系统的生态通道(Ecopath)模型, 分析和探讨了相关功能组增殖放流的生态承载力。结果显示, 七连屿珊瑚礁海域生态系统各功能群营养级范围为1.00~3.81; 生态系统的总能量转化效率为13.45%; 生态系统以牧食食物链占据主导地位, 直接来源于初级生产者的能流占比为57%。系统总初级生产量/总呼吸量为2.54; 总初级生产量/总生物量为19.07; 系统连接指数和系统杂食性指数分别为0.36和0.22, 表明当前七连屿珊瑚礁海域生态系统的成熟度和稳定性偏低, 系统对于外界的干扰抵抗能力较弱。在未改变七连屿珊瑚礁生态系统结构和功能的前提下, 各功能组中珊瑚、双壳类和植食性鱼类的生态承载力分别为25.09~53.77t•km^-2、2.55~39.95t•km^-2和4.89~17.94t•km^-2, 因此仍具有较大的增殖空间。珊瑚礁鱼类群落的最大生态承载力同珊瑚礁无脊椎动物群落的增殖密切相关, 在未来的珊瑚礁渔业管理中应从生态系统整体结构的角度综合考虑增殖放流的方法设计。     

Alongshore Sediment Transport Near Tidal Inlets of Chilika Lagoon; East Coast of India

ABSTRACT

Chilika, a lagoon along the east coast of India, is undergoing transformation due to frequent shoreline change near inlet(s). Shoreline change near inlet includes change in position and shape of inlet, inlet channel length, and spit growth/erosion. These variable features of lagoon inlet(s) critically depend on alongshore sediment transport (LST) and discharge (water and sediment) from the lagoon to the sea. The LST and the processes responsible for sand spit growth/erosion, considered as important attributes of inlet stability, are the subject matter of the present investigation and hence the study assumes importance. The study includes integration of observational and modeling framework. Observations include nearshore wave, bathymetry, beach profile, shoreline and sediment grain size of spits while numerical modeling includes simulation of the wave using MIKE 21 Spectral Wave model and LST simulation using LITtoral DRIFT. The results indicate that the predominant wave directions as S and SSE, which induces round the year south to north alongshore transport with significant seasonal variation in magnitude. The estimated LST closely matches with previous studies near Chilika inlet and for other locations along the Odisha coast. Besides temporal variability, the study reveals spatial variability in alongshore transport near Chilika inlet and considers it as one of the important attributes along with northward spit growth for inlet migration/closure/opening.     

珊瑚礁监测技术发展现状及原位在线监测建设

随着沿海地区社会和经济活动不断增加,在人类活动和全球气候变化的双重压力下,全球珊瑚礁生态健康状况日益衰退。如何有效地监测珊瑚礁生态系统,使管理部门能够及时采取保护措施防止珊瑚礁生态系统的退化,已成为拥有珊瑚礁资源的国家亟需解决的环境问题。各主要国家均在大力发展珊瑚礁监测技术与装备。文中综述了国内外在珊瑚礁生态系统监测技术方面的研究现状,基于前人提出的原位在线监测技术,在南海某岛礁海域建设了珊瑚礁生态环境原位在线监测系统,并进行了1年多的业务化运行。在业务化运行期间,原位在线监测系统成功监测到了珊瑚礁的"白化-死亡-微藻附着-珊瑚骨骼腐烂-大型藻占领"这一退化过程,表明该监测系统能够实现珊瑚礁的长期、实时、连续监测。本文研究对于进一步认识珊瑚礁生态系统的时间变化特征及其影响机制均具有重要意义。     

Coral bleaching and habitat effects on colonisation of reef fish assemblages: An experimental study

Degradation and mortality of corals is increasing worldwide and is expected to have significant effects on coral reef fish; hence studies on these effects are essential. In the present study, a field experiment was set up within Mafia Island Marine Park in Tanzania (East Africa) to examine the effects of bleaching and habitat structure on colonisation of coral reef fish assemblages. Live and bleached staghorn coral Acropora formosa was transplanted onto plots in a site dominated by sand and rubble, and the experimental design comprised of three treatments: live coral, bleached coral and eroded coral rubble. There was an immediate increase (within 24 h) in fish abundance and diversity in the two treatments with standing corals. Overall, live and bleached coral plots showed similar effects, but differed from the eroded coral plots which had a much lower abundance and diversity of fish. In general, fish species diversity changed with time over the study period while fish abundance did not. Multivariate analyses showed that while there were differences in fish assemblage structure between standing corals and the eroded coral treatment, there was neither a difference between live and bleached coral treatments nor any temporal effects on fish assemblage structure. Our findings suggest that physical structure and complexity of habitat have stronger effects on colonisation of reef fish assemblages than changes in coral health (such as bleaching) which do not affect coral structure. This may have important implications for appropriate coral reef management.     

Dissolved and particulate heavy metals distribution in coastal lagoons. A case study from Mar Chiquita Lagoon,Argentina

Mar Chiquita Coastal Lagoon is located on the Atlantic coast of Argentina, and it has been declared a Biosphere Reserve under the UNESCO Man and Biosphere Programme (MAB). This coastal lagoon constitutes an estuarine environment with a very particular behaviour and it is ecologically important due to its biological diversity. The aim of the present study was to evaluate the distribution and geochemical behaviour of several heavy metals in this coastal system, focusing on their distribution in both the dissolved phase (<0.45 μm) and the suspended particulate matter. Therefore, the general hydrochemical parameters (salinity, temperature, turbidity, pH and dissolved oxygen) and concentration of total particulate and dissolved metals (Cd, Cu, Ni, Zn, Fe, Pb, Cr and Mn) were measured along 2 years (2004–2006) at two different sites. As regards their distribution, hydrological parameters did not present any evidence of deviation with respect to historical values. Suspended particulate matter showed no seasonal variation or any relationship with the tide, thus indicating that in this shallow coastal lagoon neither tides nor freshwater sources regulate the particulate matter input. Heavy metals behaviour, both in dissolved and particulate phases did not reveal any relationship with tide or seasons. Mar Chiquita Coastal Lagoon showed a large input of dissolved and particulate metals, which is probably due to intensive agriculture within the drainage basin of this system.