New evidence for drowned shelf edge reefs in the Great Barrier Reef,Australia

We present four new high-resolution multibeam bathymetry datasets from the shelf edge of the northern Great Barrier Reef (GBR). Analysis of these data, combined with Chirp sub-bottom profiles and existing submersible observation data provides a fresh insight into the detailed morphology and spatial distribution of submerged reefs and terraces at the shelf edge. An extensive and persistent line of drowned shelf edge reefs exist on the GBR margin in about 40 to 70 m. They appear as barrier reefs up to 200 m wide and comprising twin parallel ridges of rounded pinnacles. Subtle yet consistent terrace and step features lie between 78 and 114 m seaward of the shelf edge reefs in the southern study area. Submersible observations confirm that the drowned reefs now provide a favorable hard substrate for live soft corals and algae. They form a consistent and extensive seabed habitat that extends for possibly 900 km along the GBR shelf edge. The submerged reef and terraces features may reflect a complex history of growth and erosion during lower sea-levels, and are now capped by last deglaciation reef material.     

The initiation of the southern central Great Barrier Reef: New multiproxy data from Pleistocene distal sediments from the Marion Plateau (NE Australia)

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.     

岛屿岛礁海域海浪能谱模型研究进展

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。     

江苏小庙洪牡蛎礁的地貌-沉积特征

利用卫星影象和野外实地勘察资料对江苏小庙洪牡蛎礁的地貌-沉积特征进行分析。结果表明，该牡蛎礁发育在强潮淤泥质潮坪上，造礁牡蛎主要是近江牡蛎和长牡蛎，表层的鲜活牡蛎为褶牡蛎。牡蛎礁区海水属盐度较高(27—30)的半成水，含沙量较大，为0．2—0．3g／L。活体牡蛎堆积体顶面高于周围潮间下带滩面1．0—1．5m。潮流较强，多在0．5—2．0m／s。海岸剖面可分为4个带，即礁后潮间带、潮沟、礁体生长带及礁前斜坡带。由于处于海岸侵蚀段，礁后潮坪缺失潮上带和大部分的潮间上带。礁后潮坪主要以粗粉砂为主，礁后潮沟冲淤变化较大，故礁体生长带时而为一沙洲，时而又与岸滩相连。礁体生长带分布在潮间下带，可看到独立的斑状礁体、带状礁体和大面积环状礁体群。环状礁的微地貌可以划分为礁塘(泻湖)、塘口和塘沟、塘口三角洲、礁墙和礁平台等。     

基于QuickBird影像上珊瑚礁发育状况监测实验研究

珊瑚礁生态系统具有很高的生物多样性和重要的生态功能。20世纪80年代以后全球范围内珊瑚礁的大面积退化引起了人们广泛的关注。利用高分辨多光谱QuickBird影像,基于珊瑚礁几何参数与发育指数对南沙典型岛礁发育进行遥感监测,在珊瑚礁体迎风面水域由破波形成的纹理特征表明了海面粗糙度与水下礁坪的发育特性。结果表明,南沙岛礁受地质与气候的影响发育程度不一,半月礁发育较好,发育指数为0.38,仙娥礁发育指数为0.27。建立几何参数等指标能够监测南沙珊瑚礁的发育状况,可对珊瑚礁的保护提供科学依据。     

Rapid subsidence of Kohala Volcano and its effect on coral reef growth

Evidence collected on the Kohala Terrace off northwest Hawaii shows that the volcanic edifice has subsided rapidly. This rapid subsidence, combined with Pleistocene glacio-eustactic sea level changes, twice produced relative sea level changes sufficient to drown coral reefs. Such activity can be an explanation for the paradox of reef drowning, i.e., reefs should be able to grow fast enough to avoid drowning by normal subsidence. This explanation can only accommodate the paradox under restrictive circumstances where rapid island subsidence is combined with rapid sea level changes. Because of these restrictive conditions, the general paradox of reef drowning remains.     

江苏小庙洪牡蛎礁的地貌特征及演化

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。     

Ongoing effects of no-take marine reserves on commercially exploited coral trout populations on the Great Barrier Reef

Networks of no-take marine reserves (NTMRs) are widely used for managing marine resources. Because they restrict fishing, managers need to monitor reserves to reassure stakeholders that they are achieving the intended results. In 2004, the Great Barrier Reef (GBR) Marine Park was rezoned and the area of NTMRs was greatly increased. Using manta tow we assessed the effectiveness of the new NTMRs in conserving coral trout (Plectropomus and Variola spp.), the principle targets of the GBR reef line fishery. Over a six year period, we sampled regional groups of matched pairs of similar reefs, ones closed to fishing under the rezoning and ones that remained open. Coral trout populations were significantly higher in NTMRs. While coral trout populations declined on reefs open to fishing, stocks were maintained in NTMRs, highlighting the ongoing benefits of marine reserves.     

Study of irregular wave run-up over fringing reefs based on a shock-capturing Boussinesq model

This paper presents the results of a parametric study of irregular wave run-up over fringing reefs using the shock-capturing Boussinesq wave model Funwave-TVD to better understand the role of fringing reefs in the mitigation of wave-driven flooding. Laboratory experiments were newly performed with a typical fringing reef profile and typical hydrodynamic conditions to validate the model. Experimental data shows irregular wave run-ups are dominated by the low-frequency motions and confirms the run-up resonant phenomenon over the back-reef slope, which has been revealed in previous numerical studies. It is demonstrated that irregular wave evolution and run-up over fringing reefs are reasonably reproduced by the present model with a proper grid size. However, the infragravity run-up height and highest 2% run-up height over the back-reef slope are under-predicted due to the underestimation of the infragravity wave height over the reef flat. The validated model was then utilized to model irregular wave transformations and run-ups under different conditions. Through a series of numerical experiments, the effects of key hydrodynamic and reef geometry parameters, including the reef flat width, water depth over the reef flat, fore-reef slope angle and back-reef slope angle, on the irregular wave run-up were investigated. Variations of spectral components of irregular wave run-ups were examined to better understand the physical process underlying the effect of each parameter.     

Modeling of nonlinear wave propagation over fringing reefs

The applicability of existing nonlinear (triad) spectral models for steep slopes (0.1–0.2) characteristic of reef environments was investigated, using both deterministic (phase-resolving) and stochastic (phased-averaged) formulations. Model performance was tested using laboratory observations of unidirectional wave transformation over steep and smooth bathymetry profiles. The models, developed for mild slopes, were implemented with minimal modifications (the inclusion of breaking parametrizations and linear steep-slope corrections) required by laboratory data. The deterministic model produced typically more accurate predictions than the stochastic one, but the phase averaged formulation proved fast enough to allow for an inverse modeling search for the optimal breaking parametrization. The effects of the additional assumptions of the stochastic approach resulted in a slower than observed evolution of the infragravity band. Despite the challenge posed by the fast wave evolution and energetic breaking characteristic to the steep reef slopes, both formulations performed overall well, and should be considered as good provisional candidates for use in numerical investigation of wave–current interaction processes on steep reefs.     

Socio-economic aspects of artificial reefs: Considerations for the Great Barrier Reef Marine Park

Artificial reefs are used to enhance recreational fishing and diving opportunities in the marine environment. Until recently, demand for artificial reefs in the Great Barrier Reef Marine Park (GBRMP) has been low due to the high value placed on the natural ecosystem of the Great Barrier Reef (GBR) and the abundance of fishing and diving opportunities it provides. In the GBRMP, where there are multiple stakeholder groups with diverse and often conflicting values and opinions, the deployment of artificial reefs will be a complex and controversial social issue. We review the available socio-economic literature regarding the deployment, use, and management of artificial reefs, and aim to identify and understand potential socio-economic issues and information gaps surrounding deployment of artificial reefs in the GBRMP. We also outline a strategy to guide decision-making and maximize the socio-economic value of artificial reefs should they be deployed in the GBRMP.     

海上退役平台改作鱼礁体的稳定性及流场效应研究

海洋油气平台在达到作业寿命后必须进行废弃处置,将海上退役平台改作人工鱼礁投放,对优化渔业资源、促进海洋经济持续发展具有重要意义。基于平台拆卸结构,共制作了箱状、管状、柱状、网状4种典型鱼礁实物模型,通过室内模拟试验和数值模拟研究,分析了不同鱼礁类型单体的稳定性和流场效应。结果表明：开口率0.1至0.8的箱状礁的稳定性均能满足要求,但开口率高于0.6的箱状礁难以形成连续的背涡流区域,设计时应使开口率低于0.6;管状礁应选择堆叠放置方式投放,且堆叠层数与稳定性和流场造成能力均呈正相关,在设计时尽量提高管状礁的堆叠层数;柱状礁设计时应尽量降低其重心,并减小迎流投影面的中空面积投放;基于平台的钻井架、火炬臂、栈桥设计的3种网状礁,均满足礁体稳定条件,且均能形成大范围的背涡流区域,可作为人工鱼礁投放。研究成果为平台造礁礁体结构设计提供了理论依据与实践基础,对海上退役平台的废弃处置具有一定的参考价值。     

面向岛礁应急监测的多手段组网设计与实验

为了对今后的岛礁应急监测研究提供参考和借鉴,作者以无线自组网技术为基础,提出了一种面向岛礁应急监测的多手段组网设计方案,并依托实际应用场景,开展了初步的实验,提高了岛礁监测的效率,取得了一定的数据成果。     

Formation and evolution of the tertiary carbonate reefs in the Madura Strait Basin of Indonesia

Analysis of 2 D seismic data over 4 500 km in length from the Madura Strait Basin in the East Java Sea reveals seismic re?ection characteristics of reefs and associated sedimentary bodies, including asymmetrical or symmetrical dome re?ections, slope progradational re?ections, chaotic re?ections and discontinuous strong re?ections inside the reef, which onlap the ?ank of the reef. It is concluded that the developmental paleo-environment of most reefs is mainly conducive to shallow marine carbonate platform facies and platform margin facies, based on well core data, variations in seismic facies and strata thickness.The formation and evolution of all reefs are primarily in?uenced by the tectonic framework of the Madura Strait Basin. Platform margin reefs are principally controlled by two types of structures: one is a series of E-W trending Paleogene normal faults, and the other is an E-W trending Neogene inversion structures. In addition, wave actions, tidal currents and other ocean currents play an accelerated role in sorting, rounding and redeposition for the accumulation and evolution of reefs. Tertiary reefs in the MSB can be divided into four types: 1) an open platform coral reef of Late Oligocene to Early Miocene, 2) a platform margin coral reef controlled by normal faults in Late Oligocene to Early Miocene, 3) a platform margin Globigerina moundreef controlled by a "hidden" inversion structure in Early Pliocene, and 4) a platform margin Globigerina mound-reef controlled by thrust faults in the early Pliocene. Patterns of the formation and evolution of reefs are also suggested.     

不同形状和材料的鱼礁模型对短蛸诱集效果的初步研究

采用鱼类行为学方法,观测了短蛸(Octopus ocellatus)对同为PVC材质的3种形状的有孔和无孔模型礁以及对同为管状的3种不同材料的单体和叠加模型礁的行为反应,并对各组内模型礁的诱集效果进行了比较.实验结果表明:未投放模型礁条件下短蛸在水槽四角分布率较高,在鱼礁标志区分布率只有0.5%;PVC材质3种形状的模型礁放入后对短蛸的聚集率均在10%以上,其中内部空间最大的正方体模型礁聚集率最大,每种形状的模型礁中有孔模型礁聚集率高于无孔;3种不同材料的管状模型礁放入后诱集效果均较明显,其中陶瓷材质的管状模型礁效果最好,每种材料的模型礁中3单体叠加后的组合礁聚集率明显高于单体,其中叠加后的陶瓷模型礁对短蛸的聚集率达到39.3%;研究发现短蛸的领域行为对鱼礁模型的诱集效果影响较大.     

Holocene reef growth in Torres Strait

The platform and fringing reefs of Torres Strait are morphologically similar to reefs of the northern Great Barrier Reef to the south, except that several are elongated in the direction of the strong tidal currents between the Coral Sea and the Gulf of Carpentaria. Surface and subsurface investigations and radiocarbon dating on Yam, Warraber and Hammond Islands reveal that the initiation and mode of Holocene reef growth reflect antecedent topography and sea-level history. On the granitic Yam Island, fringing reefs have established in some places over a Pleistocene limestone at about 6 m depth around 7000 years BP. Emergent Holocene microatolls of Porites sp. indicate that the reefs have prograded seawards while sea level has fallen gradually from at least 0.8 m above present about 5800 years BP. On the Warraber Island reef platform drilling near the centre indicated a Pleistocene limestone foundation at a depth of about 6 m over which reefs established around 6700 years BP. Reef growth lagged behind that on Yam Island. Microatolls on the mature reef flat indicate that the reef reached sea level around 5300 years BP when the sea was around 0.8–1.0 m above present. On the reef flat on the western side of Hammond Island bedrock was encountered at 7–8 m depth, overlain by terrigenous mud. A progradational reef sequence of only 1–2 m thickness has built seaward over these muds, as sea level has fallen over the past 5800 years. Reef-flat progradation on these reefs is interpreted to have occurred by a series of stepwise buildouts marked by lines of microatolls parallel to the reef crest, marking individual coalescing coral heads. Detrital infill has occurred between these. This pattern of reef progradation is consistent with the radiocarbon dating results from these reefs, and with seismic investigations on the Torres Reefs.     

试验水槽中多种人工鱼礁模型组合对紫红笛鲷幼鱼的诱集效果

摸清多种人工鱼礁模型组合对紫红笛鲷幼鱼的诱集效果,可为人工鱼礁礁体组合设计和礁区布局设计等方面提供科学依据.本研究参照深圳杨梅坑人工鱼礁区的实际建礁情况,制作并模拟4组三种模型礁体组合、4组四种模型礁体组合,在方形试验水槽中以鱼类行为学的方法研究了这8组模型礁体组合对紫红笛鲷的诱集效果.4组三礁组合礁体模型试验结果表明,FHJ三礁组合对紫红笛鲷的集鱼效果非常明显,BFH、BCG、CHJ三礁组合对紫红笛鲷的集鱼效果较为明显.其诱集效果排序为:FHJ组合礁(53.84%)>BFH组合礁(44.85%)>BCG组合礁(38.11%)>CHJ组合礁(36.01%).4组四礁组合礁体的试验结果表明,4组四礁组合礁体模型对紫红笛鲷均具有较强的诱集效果,其诱集效果排序为:BGHJ组合礁(52.27%)>CFHJ组合礁(51.26%)>BCGJ组合礁(50.01%)>BCGH组合礁(45.05%).总体上,四礁组合的诱集效果优于三礁组合,人工鱼礁建设的礁群配置以多礁组合为佳.     

CotSim—an interactive Acanthaster planci metapopulation model for the central Great Barrier Reef

CotSim is a size-structured metapopulation model of the crown-of-thorns (Acanthaster planci) on the central Great Barrier Reef (GBR). The populations of starfish and the coral cover on 269 individual reefs are modelled for up to 200 years. Starfish are represented as larvae, two age classes of juveniles and three size classes of adults. Coral can either be modelled as a single type or as two types each with a characteristic growth rate, equilibrium cover and susceptibility to starfish predation. Reefs are connected using simulated dispersal data for A. planci on the central GBR. These data were generated using a particle tracking program where simulated currents displaced particles representing dispersing larvae after an A. planci spawning episode. The dispersal data represented patterns expected from the 1976/77 to 1989/90 spawning season. The starfish growth model is a density-dependent matrix model. When coral cover is low, survival within classes is low and the transitions into larger classes is impeded. In contrast, at high coral cover the reverse patterns occur. Both the starfish and coral data are filtered through an interpretation model to generate observed patterns. The starfish interpretation model represents the important difficulty in detecting smaller adults. Results from the model using the default parameters correspond with published patterns of starfish/coral dynamics and the overall patterns of starfish outbreaks on the GBR.The model is an interactive event-driven 32-bit Windows application requiring Windows 95 or Windows NT 3.51/4.0. Most parameters are able to be altered by the user with three tabbed dialogue boxes (for the simulation, starfish and coral parameters). Biologically justifiable default parameters are provided for all parameters. Parameters and initial starfish populations are stored in simple coded ASCII files. Simulations are controlled using ‘Run’, ‘Pause/Continue’ and ‘Stop’ operations. Maps of the GBR illustrate the spatial and temporal structure of the metapopulation dynamics including the patterns of dispersal. Once paused, populations on individual reefs can be examined using two types of plots (time series and single time bar charts). Overall patterns can be displayed using latitude versus time plots of observed reef state. Starfish populations and coral cover can be edited, which enables users of the model to become associated with some of the key issues regarding large-scale starfish control programs. Results from the model can be written to ASCII files for additional analysis. The speed of a simulation is able to be controlled and colours for important graphical elements can be altered. CotSim includes indexed online context-sensitive help and a graphical install routine. The program adheres to published guidelines for Windows applications.     

渤海湾西北岸全新世埋藏牡蛎礁建造记录中的间断及其解释

渤海湾西北岸沿海平原的众多埋藏牡蛎礁体内部,除正常牡蛎壳堆积层外,还存在一些水平夹层,以往的文献对其成因有多种解释。对渤海湾西北岸埋藏牡蛎礁体中所含水平夹层特征进行了研究,并与江苏海岸南部现代活体牡蛎礁顶部沉积特征进行对比,结果表明渤海湾埋藏礁体中局部范围内分布的水平夹层与江苏海岸活礁体顶部的现代沉积相似,其特征与礁体生长时的局部水动力条件有关;但是,江苏海岸活牡蛎礁顶部的现代沉积特征不同于那些大范围分布于埋藏礁体内的水平夹层的特征,后者的成因尚待进一步研究。礁体剖面记录的垂向层序,在反映环境演化的同时,也反映了礁体生长时的平面特征。     

川东北宣汉盘龙洞长兴组生物礁剖面沉积相分析

结合区域构造、地层概况、岩相古地理等方面的背景资料,对宣汉盘龙洞上二叠统长兴组生物礁地层剖面进行了观测描述。通过室内镜下岩石薄片鉴定分析,识别出主要岩石类型为礁灰岩、礁云岩、生屑灰岩、颗粒灰岩及晶粒白云岩。根据露头观察和室内镜下岩石薄片鉴定分析,结合岩石学、古生物等沉积相标志的研究,认为该剖面发育开阔台地、台地边缘生物礁和台地边缘浅滩三种沉积相类型,其中台地边缘生物礁发育,可进一步识别出礁基、礁核和礁前亚相,礁核以骨架礁和障积礁为主;台地边缘浅滩进一步划分为粒屑滩、鲕粒滩等亚相。初步总结出了该剖面的沉积相模式,并对该剖面的沉积演化序列和识别标志进行了讨论。