Liquefaction susceptibility and deformation characteristics of saturated coral sandy soils subjected to cyclic loadings——a critical review

Coral sandy soils widely exist in coral island reefs and seashores in tropical and subtropical regions. Due to the unique marine depositional environment of coral sandy soils, the engineering characteristics and responses of these soils subjected to monotonic and cyclic loadings have been a subject of intense interest among the geotechnical and earthquake engineering communities. This paper critically reviews the progress of experimental investigations on the undrained behavior of coral sandy so...     

Tropical harmful algal blooms: An emerging threat to coral reef communities?

Tropical harmful algal blooms (HABs) are increasing in frequency and intensity and are substantially affecting marine communities. In October/November 2008 a large-scale HAB event (> 500 km², dinoflagellate Cochlodinium polykrikoides) in the Gulf of Oman caused the complete loss of the branching corals, Pocillopora and Acropora spp., and substantial reductions in the abundance, richness and trophic diversity of the associated coral reef fish communities. Although the causative agents of this C. polykrikoides bloom are unknown, increased coastal enrichment, natural oceanographic mechanisms, and the recent expansion of this species within ballast water discharge are expected to be the main agents. With rapid changes in oceanic climate, enhanced coastal eutrophication and increased global distribution of HAB species within ballast water, large-scale HAB events are predicted to increase dramatically in both intensity and distribution and can be expected to have increasingly negative effects on coral reef communities globally.     

Correlation between δ~(18)O,Sr/Ca and Mg/Ca of coral Acropora and seawater temperature from coral culture experiments

To be used as proxies of seawater surface temperature(SST), the δ 18Oc values and Sr/Ca and Mg/Ca ratios of scleractinian coral skeletons must be verified by coral culture experiments in the laboratory. This paper describes a coral culture experiment that was conducted at several seawater temperatures T(21–28°C) using a tandem aquarium system and the new method for depositing coral skeletons grown under controlled conditions. The δ 18Oc values and the Sr/Ca and Mg/Ca ratios of the cultured coral were measured. We concluded that the δ 18Oc values and Sr/Ca and Mg/Ca ratios of the cultured coral are clearly correlated with T. The linear regression curve is δ18Oc(‰)=δ0.1427δT(°C)δ0.1495(n=18, r=0.955, p0.0001), and the slope of δ0.1427‰/°C is at the low end of the range of published values(δ0.13–δ0.29‰/°C). The Sr/Ca ratio decreases with increasing T, whereas the Mg/Ca ratio increases with increasing T, indicating a negative correlation between Sr/Ca and Mg/Ca. Their linear regression curves are Sr/Ca(mmol/mol)=δ0.04156δT+10.59(n=15, r=0.789, p0.005) and Mg/Ca(mmol/mol)= 0.04974δT+2.339(n=17, r=0.457, p0.05), respectively, which demonstrate that when Mg/Ca and Sr/Ca are increased by one unit, T increases by 5.19°C and decreases by 15.62°C, respectively. These variations are significantly lower than published values.     

Assessing fertilization success of the coral Montipora capitata under copper exposure: Does the night of spawning matter?

Metal pollution is a major threat in tropical areas due to increasing pressure from anthropogenic activities along coastlines. Unfortunately there are very few toxicological studies that assess the effects of metals on marine organisms in tropical areas. To help fill this gap, this study investigated how Cu alters the fertilization success of the coral Montipora capitata over several nights of spawning. Results indicate that gametes of M. capitata are sensitive to Cu pollution, with EC₅₀ after 3 h ranging from 16.6 to 31.7 μg l^?1. Moreover, the sensitivity of the gametes to Cu toxicity was influenced by the night of spawning during which fertilization experiments were performed. This result likely reflected changes in the quality of gamete over the spawning period.     

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.     

The use of δN in assessing sewage stress on coral reefs

While coral reefs decline, scientists argue, and effective strategies to manage land-based pollution lag behind the extent of the problem. There is need for objective, cost-effective, assessment methods. The measurement of stable nitrogen isotope ratios, δ¹⁵N, in tissues of reef organisms shows promise as an indicator of sewage stress. The choice of target organism will depend upon study purpose, availability, and other considerations such as conservation. Algae are usually plentiful and have been shown faithfully to track sewage input. The organic matrix of bivalve shells can provide time series spanning, perhaps, decades. Gorgonians have been shown to track sewage, and can provide records potentially centuries-long. In areas where baseline data are lacking, which is almost everywhere, δ¹⁵N in gorgonians can provide information on status and trends. In coral tissue, δ¹⁵N combined with insoluble residue determination can provide information on both sewage and sediment stress in areas lacking baseline data. In the developed world, δ¹⁵N provides objective assessment in a field complicated by conflicting opinions. Sample handling and processing are simple and analysis costs are low. This is a method deserving widespread application.     

Can dynamite-blasted reefs recover? A novel, low-tech approach to stimulating natural recovery in fish and coral populations

Throughout Southeast Asia, blast fishing creates persistent rubble fields with low coral cover and depauperate fish communities. We stabilized a 20-year-old rubble field in a Marine Protected Area in the Philippines, using plastic mesh and rock piles in replicated 17.5m(2) plots, thereby increasing topographic complexity, fish habitat, and recruitment substrate surface area. Multivariate analysis revealed fish community shifts within the rehabilitated area from that characteristic of rubble fields to one similar to the adjacent healthy reef within three years, as measured by changes in fish abundance and body size. Coral recruitment and percent cover increased over time, with 63.5% recruit survivorship within plots, compared with 6% on rubble. Our low-cost approach created a stable substrate favoring natural recovery processes. Both rehabilitation and the elimination of poaching were integral to success, emphasizing the synergism between the two and the need to incorporate both when considering mitigation.     

Invitation of Contributions to the International Journal of Sediment Research

Dear Colleagues:We would like to draw your attention to recent developments with the International Journal ofSediment Research. The Journal has been published by the International Research and Training     

Unique recovery stage of reef communities after F/F event in a huge coral reef of Carboniferous, Southern Guizhou,China

Carboniferous is a global recession period of reef-building. There were fewer reefs at that times due to massive extinction and the great glacial catastrophe in the southern hemisphere in Frasnian/Famennian[1]. So far, however, most of the researches concerning Carboniferous reefs have been limited, which leads to insufficient knowledge regarding the composition, structure, ecological characteristics of reef-building communities, the reef growth models, etc. Interna-tional studies conducted o…     

Application of digital image processing to the determination of spatial distribution of earthquakes

（陈锦标，沈萍，郑治真）Ａｐｐｌｉｃａｔｉｏｎｏｆｄｉｇｉｔａｌｉｍａｇｅｐｒｏｃｅｓｓｉｎｇｔｏｔｈｅｄｅｔｅｒｍｉｎａｔｉｏｎｏｆｓｐａｔｉａｌｄｉｓｔｒｉｂｕｔｉｏｎｏｆｅａｒｔｈｑｕａｋｅｓ￥Ｊｉｎ－ＢｉａｏＣＨＥＮ；ＰｉｎｇＳＨＥＮａｎｄＺ...     

A new approach to numerical simulation of source development of earthquake

ＡｎｅｗａｐｐｒｏａｃｈｔｏｎｕｍｅｒｉｃａｌｓｉｍｕｌａｔｉｏｎｏｆｓｏｕｒｃｅｄｅｖｅｌｏｐｍｅｎｔｏｆｅａｒｔｈｑｕａｋｅＣＨＵＮ－ＡＮＴＡＮＧ（唐春安）ＹＵ－ＦＡＮＧＦＵ（傅宇方）ＷＥＮＺＨＡＯ（赵文）ＣｅｎｔｅｒｆｏｒＲｏｃｋｂｕｒｓｔｓ...     

Possibility of Application of the Electromagnetic Missile Theory to Earthquake Prediction

Geoeiectromagnetic signals related to earthquakes have been detected in China and many other countries.Problems concerning the mechanism of the electromagnetic emission and transportation still remain unsolved,although several models have been proposed.We consider that the theory of "electromagnetic missile emission" may be used to solve this problem,and thus develops the basic ideal of the Electro Magnetic Missile Emission(EMME)model of the emission of electromagnetic signals before earthquakes:pulse variation of the stress state causes the emission of electrons,or sudden flow of the fluid,in a certain direction along or near the fault which is located at the focus of an earthquake,forming a pulse electric current; this current accordingly produces a kind of slowly attenuated EM Wave(electromagnetic missile,which may be observed on the surface of the earth)in the perpendicular direction.In other directions these EM waves vanish quickly and cannot reach ground level.     

Interannual variations of bomb radiocarbon during 1977—1998 recorded in coral from Daya Bay, South China Sea

Radioactive isotope tracers such as 14C, 3H, 222Rn and 226Ra are extensively applied in oceanological research, simply because these radioactive isotopes can be indicative of some ex-tremely slow processes occurring in sea water, which may include the off…     

Interannual variations of bomb radiocarbon during 1977– 1998 recorded in coral from Daya Bay,South China Sea

22 annual layered samples of coral from 1977 to 1998 were collected from Daya Bay, South China Sea, their bomb-¹⁴C (nuclear weapons testing¹⁴C) concentrations were determined and studied, and the atmosphere-sea exchange rate and diffusion thickness were estimated and found to be 17 mol · m⁻² · a⁻¹ and 32 μm, respectively. The interannual variation of coral Δ¹⁴C is mainly controlled by oceanic factors. In ENSO years, the coastwise upwelling current of South China Sea gets intensified, hence the coral Δ¹⁴C displays its bottom value. The coral Δ¹⁴C does no respond vividly to the variation of the solar radiation energy. In the past 20 years or so, the genera situation and the oceanic thermal structure of South China Sea are still stable even though inter annual variation occurs in the atmosphere-sea interaction and the upwelling current driven by the tropical energy.     

Application of mechanical and statistical models to the study of seismicity of syn-thetic earthquake

Ａｐｐｌｉｃａｔｉｏｎｏｆｍｅｃｈａｎｉｃａｌａｎｄｓｔａｔｉｓｔｉｃａｌｍｏｄｅｌｓｔｏｔｈｅｓｔｕｄｙｏｆｓｅｉｓｍｉｃｉｔｙｏｆｓｙｎ－ｔｈｅｔｉｃｅａｒｔｈｑｕａｋｅｓａｎｄｔｈｅｐｒｅｄｉｃｔｉｏｎｏｆｎａｔｕｒａｌｏｎｅｓＹＡＯ－ＬＩＮＳ...     

The application of resistivity tomography to hydrogeological exploration

ＴｈｅａｐｐｌｉｃａｔｉｏｎｏｆｒｅｓｉｓｔｉｖｉｔｙｔｏｍｏｇｒａｐｈｙｔｏｈｙｄｒｏｇｅｏｌｏｇｉｃａｌｅｘｐｌｏｒａｔｉｏｎＲＵＩＦＥＮＧ１）（冯锐）ＸＩＡＯ－ＱＩＮＬＩ２）（李晓芹）ＹＵ－ＬＵＴＡＯ２）（陶裕录）ＣＩ－ＣＨＡＮＧＳＵＮ２）（...     

Application of the Linearity Method to Processing and Analyzing of Precursory Data

In this paper,the spatial linearity method is applied to synthetical processing of precursory data from different stations and different disciplines.The new characteristic value(a)obtained can describe the whole precursory field.The authors present the formulas for calculating spatial linearity.Furthermore,the spatial linearity method is applied to processing of geoelectrical resistivity and groundwater level data from 1970 to 1994 in North China.The results show that the new characteristic value(a)could detect the anomaly 1 year before moderately strong earthquakes.     

Increase of Local Seismicity Due to the Construction of Taipei 101？

Considering the controversy over whether the Taipei 101 skyscraper has induced an increase of local seismicity, we reanalyzed the local earthquake catalogue before and after the construction to investigate whether the reported seismicity increase related to the construction is statistically significant. Statistical tests obtained a positive conclusion about the apparent seismicity increase. However, the calculation of maximum ΔCFS shows that at most a 2.2×10-4 bar Coulomb Failure Stress change was produced by the construction. Therefore, whether the construction of Taipei 101 really triggered the increase of seismicity still remains an open question: Statistically-yes; physically-no.