珊瑚礁海岸水动力学问题研究综述

珊瑚礁水动力学是一个涉及生态、环境、地质和工程学的交叉课题,其水动力学研究不仅为珊瑚礁海域生态系统的维护和海岸线的演变提供一定的理论参考,还能为海岸的防灾减灾以及岛礁工程的建设提供一定的决策依据。回顾了国内外珊瑚礁海岸水动力问题的研究与进展,从现场观测、理论模型、物理模型试验和数值模型4个方面对当前该领域的研究进展进行了综述,并提出今后现场观测研究对象可关注南中国海的珊瑚岛礁,理论分析方法可侧重考虑非线性波浪理论,物理模型试验可采用大型波浪水槽和港池来复演现场尺度的水动力问题,数值模型可采用计算流体力学（Computational Fluid Dynamics,CFD）方法对波浪与珊瑚礁相互作用进行精细化模拟,本文旨在为今后国内珊瑚礁水动力学方面的相关研究提供一定的借鉴和参考。     

广西涠洲岛海域珊瑚礁现状及其保护策略研究

通过对2005年涠洲岛珊瑚礁生态调查,结合对以往资料和数据的分析,对比1984年和1964年2次调查结果,掌握涠洲岛珊瑚礁的现状.同时讨论了涠洲岛珊瑚礁区面临的生存威胁,提出保护和管理涠洲岛珊瑚礁的建议,以期建立可持续的生态旅游开发与新型的生态保护生态管理体系.     

Sewage impacts coral reefs at multiple levels of ecological organization

Against a backdrop of rising sea temperatures and ocean acidification which pose global threats to coral reefs, excess nutrients and turbidity continue to be significant stressors at regional and local scales. Because interventions usually require local data on pollution impacts, we measured ecological responses to sewage discharges in Surin Marine Park, Thailand. Wastewater disposal significantly increased inorganic nutrients and turbidity levels, and this degradation in water quality resulted in substantial ecological shifts in the form of (i) increased macroalgal density and species richness, (ii) lower cover of hard corals, and (iii) significant declines in fish abundance. Thus, the effects of nutrient pollution and turbidity can cascade across several levels of ecological organization to change key properties of the benthos and fish on coral reefs. Maintenance or restoration of ecological reef health requires improved wastewater management and run-off control for reefs to deliver their valuable ecosystems services.     

Does use of tropical beaches by tourists and island residents result in damage to fringing coral reefs? A case study in Moorea French Polynesia

Although coral reefs worldwide are subject to increasing global threats, humans also impact coral reefs directly through localized activities such as snorkeling, kayaking and fishing. We investigated five sites on the northern shore of Moorea, French Polynesia, and quantified the number of visitors on the beach and in shallow water. In field surveys, we measured total coral cover and colony sizes of two common genera, Porites and Acropora, a massive and branching morphology, respectively. One site, which hosted over an order of magnitude more people than the other four, had significantly less total coral cover and supported very little branching Acropora. In addition, size frequency distributions of both the branching and massive genera were skewed toward smaller colony sizes at the high use site. Our results demonstrated that the use of tropical beaches may result in less coral cover, with branching colonies rare and small.     

Land-based nutrient enrichment of the Buccoo Reef Complex and fringing coral reefs of Tobago, West Indies

Tobago’s fringing coral reefs (FR) and Buccoo Reef Complex (BRC) can be affected locally by wastewater and stormwater, and regionally by the Orinoco River. In 2001, seasonal effects of these inputs on water-column nutrients and phytoplankton (Chl a), macroalgal C:N:P and δ¹⁵N values, and biocover at FR and BRC sites were examined. Dissolved inorganic nitrogen (DIN, particularly ammonium) increased and soluble reactive phosphorus (SRP) decreased from the dry to wet season. Wet season satellite and Chl a data showed that Orinoco runoff reaching Tobago contained chromophoric dissolved organic matter (CDOM) but little Chl a, suggesting minimal riverine nutrient transport to Tobago. C:N ratios were lower (16 vs. 21) and macroalgal δ¹⁵N values higher (6.6‰ vs. 5.5‰) in the BRC vs. FR, indicating relatively more wastewater N in the BRC. High macroalgae and low coral cover in the BRC further indicated that better wastewater treatment could improve the health of Tobago’s coral reefs.     

Microfacies and Depositional Environments of Miocene Isolated Carbonate Platforms from Central Luconia, Offshore Sarawak, Malaysia

The Luconia Province – offshore Sarawak – is a key geological unit for understanding the distribution of hydrocarbon resources in Malaysia. Nevertheless, little effort has been made to address the palaeoenvironmental characteristics of the Tertiary carbonates in the key sector of Central Luconia. We study the sedimentology and petrography of core samples from a well in Central Luconia, for which thirteen microfacies have been identified reflecting different depositional settings. This is the first microfacies scheme elaborated for Luconian carbonates. Lithofacies and microfacies distribution are compatible with deposition in a reef complex, originating around a framework reef, within the euphotic zone. Sediments were deposited in environments of backreef, reef crest, and forereef. The fair weather wave base is marked by the presence of coralline red algae, foraminifera, decreasing degree of bioclast fragmentation and other microfacies features. As a result, a depositional-environmental model is constructed, depicting a reef complex built around a framework reef developed on the margin of an isolated platform. In addition, an innovative, preliminary time series analysis of facies, microfacies and depositional environment data reveal the existence of seasonal cycles in the stacking patterns of facies and microfacies.     

多孔介质储层表征技术在塔中地区上奥陶统礁滩储层中的应用

多孔介质储层表征技术应用岩心分析、测井分析、地震分析、岩样实验分析、生产动态分析等多种分析方法,表征不同尺度储集空间及其组合特征,最终评价有利储层。应用该技术,识别塔中地区北斜坡奥陶系良里塔格组孔隙型、孔洞型、孔隙-孔洞型、缝洞型和孔缝洞型5类储层,并表征了各类储层的孔喉结构、孔渗性和产能特征。结果表明：孔隙-孔洞型储层的孔喉结构发育大孔大喉的孔喉结构,优于孔隙型和孔洞型储层;裂缝对各类储层起到改善作用,裂缝的发育增加了储层孔渗性和连通性;储层产能特征受储层类型及规模影响,台缘孔缝洞型、孔隙-孔洞型储层以高产稳产为特征,台内缝洞型储层以中产较稳产为特征,台内孔洞型储层以中低产不稳产为特征。各类储集空间组合类型中,台缘孔缝洞型、孔隙-孔洞型储层是最有利储层,台内缝洞型是目前台内勘探的主要类型,台内孔隙型、孔洞型储层在裂缝发育情况下可以形成潜力储层。     

The Diagenesis of Coral Reefs

Coral reefs are often constrained by diagenesis as a sound environmental archive. The correct understanding and evaluation of diagenesis is the key to the paleoenvironmental reconstruction of coral reefs. The diagenesis of coral reefs mainly includes cementation, dissolution, neomorphism and dolomitization etc. On the one hand, the diagenesis itself can record the paleoenvironment that coral reefs underwent, such as sea-level fluctuation, climate change, change of sea water, hydrothermal alteration, microbial activity and so on. The diagenetic evolution thus can be used for the reconstruction of paleoenvironment change. On the other hand, diagenesis also destroys the original environmental information which recorded of coral reefs recard, and it is necessary to know the degree of the impact of diagenesis. In the future, we should pay more attention to the study on the relationships among diagenesis, modern climate, sea-level change, atmospheric water transformation and microbial activity. It can provide more accurate and longer time series of paleoenvironmental information that coral reefs recorded.     

Study on wave-induced setup over fringing reefs in the presence of a reef crest

It has been well observed that a reef crest (ridge) may be present at the reef edge, but so far very few published studies focusing on the effects of such reef-crest on the wave dynamics over fringing reefs. To understand the role of a reef-crest configuration in determining breaking-wave induced setup over the reef flat, a series of experiments were carried out in a wave flume using an idealized fringing reef model with a reef crest. Experimental results were reported for a trapezoidal reef crest with five reef-crest widths under a series of monochromatic waves. Also examined was the reef without a reef crest. Data analysis shows that larger energy dissipation associated with smaller surfzone width around the reef edge occurred with a wider reef crest. The maximum wave-induced setup on the reef flat in the presence of the reef crest was significantly larger than that without, and it also increased with increasing reef-crest width. The reef-crest submergence was found to be a primary parameter controlling the magnitude of wave setup on the reef flat provided that the reef crest was sufficient wide. An alternative semi-analytical 1DH model based on the balance of cross-shore momentum was proposed. The model was validated by present laboratory data as well as three existing 1DH laboratory studies. Comparing with other two representative semi-analytical models in the literature showed that the proposed model was capable of better reproducing the maximum wave-induced setup on the reef flat for a variety of reef profiles with/without a reef crest, different reef-crest water levels, as well as both monochromatic and spectral waves. The model parameter was physically related to the two characteristic lengths in the surf zone and its value was dependent on the fore-reef slope as well as the presence of a reef crest. The 1DH model was also satisfactorily applied to a fringing reef in field conditions where the effects of fore-reef friction and back-reef lagoon were not important.