Erratum to: Seasonal dynamics of Symbiodiniaceae communities associated with nine coral species in Luhuitou coral reef, South China Sea

BackgroundScleractinian corals are important reef builders, but around the world they are under the threat of global climate change as well as local stressors. Molecular resources are critical for understanding a species’ stress responses and resilience to the changing environment, but such resources are unavailable for most scleractinian corals, especially those distributed in the South China Sea. We therefore aimed to provide transcriptome resources for 14 common species, including a few structure forming species, in the South China Sea.DescriptionWe sequenced the transcriptome of 14 species of scleractinian corals using high-throughput RNA-seq and conducted de novo assembly. For each species, we produced 7.4 to 12.0 gigabases of reads, and assembled them into 271 to 762 thousand contigs with a N50 value of 629 to 1427 bp. These contigs included 66 to 114 thousand unigenes with a predicted open reading frame, and 74.3 to 80.5% of the unigenes were functionally annotated. In the azooxanthelate species Tubastraea coccinea, 41.5% of the unigenes had at least a best-hit sequence from corals. In the other thirteen species, 20.2 to 48.9% of the annotated unigenes had best-hit sequences from corals, and 28.3 to 51.6% from symbiotic algae belonging to the family Symbiodinaceae. With these resources, we developed a transcriptome database (CoralTBase) which features online BLAST and keyword search for unigenes/functional terms through a user friendly Internet interface.Short conclusionWe developed comprehensive transcriptome resources for 14 species of scleractinian corals and constructed a publicly accessible database (www.comp.hkbu.edu.hk/~db/CoralTBase). CoralTBase will facilitate not only functional studies using these corals to understand the molecular basis of stress responses and adaptation, but also comparative transcriptomic studies with other species of corals and more distantly related cnidarians.

Short-term thermal acclimation improved the thermal tolerance of three species of scleractinian corals in the South China Sea

The scleractinian coral species, Seriatopora hystrix and Acropora longicyathus, are widely distributed throughout the latitudinal range of the tropical west Pacific. These 2 coral species live in a mutually beneficial relation with symbiotic dinoflagellates (zooxanthellae), which are passed to their progeny by vertical transmission (zooxanthellate eggs or larvae) and horizontal transmission (eggs or larvae that acquire symbionts from the environment), respectively. For S. hystrix, vertical transmission might create biogeographically isolated and genetically differentiated symbiont populations because the extent of its larval migration is known to be limited. On the other hand, horizontal transmission in corals such as A. longicyathus may result in genetically connected symbiont populations, especially if its zooxanthellae taxa are widely distributed. To examine these hypotheses, symbionts were collected from colonies of S. hystrix and A. longicyathus living in the Great Barrier Reef (Australia), South China Sea (Malaysia) and East China Sea (Ryukyus Archipelago, Japan), and were examined using restriction fragment length polymorphism and sequence analysis of large and small subunit rRNA genes. Phylogenetic analysis assigned the symbionts to 1 of 3 taxonomically distinct groups, known as clades. Symbionts from Australian and Japanese S. hystrix were placed in Clade C, and Malaysian S. hystrix symbionts in the newly described Clade D. Seven of 11 Australian and all Japanese and Malaysian colonies of A. longicyathus had symbiotic dinoflagellates that also grouped with Clade C, but symbionts from the remaining Australian colonies of A. longicyathus grouped with Clade A. Analysis of molecular variance of Clade C symbionts found significant genetic variation in 1 or more geographic groups (69.8%) and to a lesser extent among populations within geographic regions (13.6%). All populations of Clade C symbionts from S. hystrix were genetically differentiated according to geographic region. Although Clade C symbionts of A. longicyathus from Japan resolved into a distinct geographic group, those from Australia and Malaysia did not and were genetically connected. We propose that these patterns of genetic connectivity correlate with differences in the dispersal range of the coral or symbiont propagules and are associated with their respective modes of symbiont transmission.

Recent deep-sea benthic foraminiferal distributions in the South China and Sulu Seas

Occurrence, distribution and seasonal variation of chlorinated paraffins in coral communities from South China Sea

Population genetic structure of Montipora digitata coral-algal symbiosis in the South China Sea

Abstract. This paper investigates the acetone variability in the upper troposphere (UT) as sampled during the CARIBIC airborne experiment and simulated by the LMDz-INCA global chemistry climate model. The aim is to (1) describe spatial distribution and temporal variability of acetone; (2) propose benchmarks deduced from the observed data set; and (3) investigate the representativeness of the observational data set. According to the model results, South Asia (including part of the Indian Ocean, all of India, China, and the Indochinese peninsula) and Europe (including Mediterranean Sea) are net source regions of acetone, where nearly 25 % of North Hemispheric (NH) primary emissions and nearly 40 % of the NH chemical production of acetone take place. The impact of these net source regions on continental upper tropospheric acetone is studied by analysing CARIBIC observations of 2006 and 2007 when most flight routes stretched between Frankfurt (Germany) and Manila (Philippines), and by focussing over 3 sub-regions where acetone variability is strong: Europe-Mediterranean, Central South China and South China Sea. Important spatial variability was observed over different scales: (1) east-west positive gradient of annually averaged acetone vmr in UT over the Eurasian continent, namely a factor two increase from east to west; (2) ocean/continent contrast with 50 % enhancement over the continents; (3) the acetone volume mixing ration (vmr) may vary in summer by more than 1000 pptv within only 5 latitude-longitude degrees; (4) the standard deviation for measurements acquired during a short flight sequence over a sub-region may reach 40 %. Temporal variability is also important: (1) the acetone volume mixing ratio (vmr) in the UT varies with the season, increasing from winter to summer by a factor 2 to 4; (2) a difference as large as 200 pptv may be observed between successive inbound and outbound flights over the same sub-region due to different flight specifications (trajectory in relation to the plume, time of day). A satisfactory agreement for the abundance of acetone is found between model results and observations, with e.g. only 30 % overestimation of the annual average over Central-South China and the South China Sea (between 450 and 600 pptv), and an underestimation by less than 20 % over Europe-Mediterranean (around 800 pptv). Consequently, annual budget terms could be computed with LMDz-INCA, yielding a global atmospheric burden of 7.2 Tg acetone, a 127 Tg yr−1 global source/sink strength, and a 21-day mean residence time. Moreover the study shows that LMDz-INCA can reproduce the impact of summer convection over China when boundary layer compounds are lifted to cruise altitude of 10–11 km and higher. The consequent enhancement of acetone vmr during summer is reproduced by LMDz-INCA, to reach agreement on an observed maximum of 970 ± 400 pptv (average during each flight sequence over the defined zone ± standard deviation). The summer enhancement of acetone is characterized by a high spatial and temporal heterogeneity, showing the necessity to increase the airborne measurement frequency over Central-South China and the South China Sea in August and September, when the annual maximum is expected (daily average model values reaching potentially 3000 pptv). In contrast, the annual cycle in the UT over Europe-Mediterranean is not reproduced by LMDz-INCA, in particular the observed summer enhancement of acetone to 1400 ± 400 pptv after long-range transport of free tropospheric air masses over North Atlantic Ocean is not reproduced. In view of the agreement on the acetone annual cycle at surface level, this disagreement in UT over Europe indicates misrepresentation of simulated transport of primary acetone or biased spatial distribution of acetone chemical sinks and secondary sources. The sink and source budget in long-range transported free tropospheric air masses may be studied by analysing atmospheric chemical composition observed by CARIBIC in summer flights between North America and Europe.

Sediment cores from the South China and Sulu seas have been used to study sea surface temperature changes in these two western equatorial Pacific basins during the last 25,000 years. Sea surface temperature (SST) estimates were derived using the planktonic foraminiferal transfer function FP‐12E previously developed by Thompson (1981). The water depths for the cores range from 500 m to more than 4,000 m and thus provide a good opportunity to evaluate the effect of carbonate dissolution on quantitative paleotemperature estimates. The sea surface temperature time series from shallow, well‐preserved cores indicate that average winter and summer temperatures during the Holocene were approximately 27°C and 29.5°C, respectively, for both the South China and Sulu seas. These estimates agree well with modern observations. During the last glacial maximum, summer sea surface temperatures were approximately 28.5°C in the South China Sea and 29°C in the Sulu Sea and thus were very similar to the Holocene. In contrast, glacial winter sea surface temperatures are estimated at approximately 21°C for the South China Sea and 24°C for the Sulu Sea. This decrease in glacial winter sea surface temperatures results in a much larger seasonality during the last glacial (5°‐8°C) compared to the Holocene (2°C). These seasonal contrasts are much greater than those estimated by Climate: Long‐Range Investigation, Mapping, and Prediction Members (1981) for this region of the western equatorial Pacific. Variation in intensity of the monsoon system and surface water exchange rates between these basins and the open ocean are the major factors controlling glacial‐interglacial SST fluctuations in the South China and Sulu seas. One factor influencing the accuracy of the SST estimates is the quality of preservation of the planktonic foraminiferal assemblages. Our results demonstrate that depth‐dependent increases in dissolution result in systematically cooler SST estimates. This is due to the fact that warm water planktonic foraminifera tend to be more solution susceptible, and as dissolution progresses, the assemblage becomes enriched in the more resistant, cooler water taxa. Since dissolution is more intense during interglacials than glacials in the Pacific, dissolution tends to reduce the amplitude of the glacial‐interglacial temperature difference.

In exploring hidden risks to the international system, this issue has covered a variety of functional, regional, and theoretical topics; however, with U.S. foreign policy focus shifting to Asia, it is not surprising that many authors draw their attention to the South China Sea. Marvin Ott’s “Southeast Asia’s Strategic Landscape,” Charles Doran’s “Power Cycle Theory and the Ascendance of China,” Chris Ford’s “Soft on Soft Power,” and Ian Bremmer’s interview all touch in some way on potential conflict in the South (and East) China Seas. As Sino-Taiwanese relations warm following the January 2012 re-election of Taiwanese President Ma Ying-jeou, who has made strengthening ties with the mainland a priority of his administration, the South China Sea will become the preeminent focus of U.S.-China watchers who study potential military clashes between the two countries. Given the shifting attention to the issue, the risk of conflict in the South China Sea is not particularly “hidden.” Indeed, over the last two years, the United States has paid increasing attention to the region, most evident by Secretary of State Hillary Clinton’s reassertion of U.S. interests there at the ASEAN ministerial meetings in Hanoi in July 2010 1 and President Obama’s emphasis of the same concerns at the November 2011 East Asia Summit. 2 The essential dynamics are well-covered by popular media and clearly understood from traditional theories of international relations: a rising power, China, competes with a status quo hegemon, the United States, for influence in a complicated multipolar regional context across a variety of military, diplomatic, and economic fronts. The South China Sea is particularly well-suited for such competition as, beyond its large economic and strategic importance as a global crossroads, it is a source of vast, untapped natural resources. Though the overarching risk of tension in the South China Sea is not hidden, policymakers in Washington should be clear on the actual dangers posed by conflict as they begin to consider future U.S. competition with

Japan’s principal security interest in Southeast Asia is the safety and security of regional sea lanes. Over the past several years, Japan has expressed growing concern at rising tensions in the South China Sea and the lack of progress by the claimants to negotiate effective conflict management mechanisms. Japan is not a claimant in the dispute, but as a major maritime trading nation, it is a significant stakeholder. Japan has two major concerns over the South China Sea. First, that instability has the potential to disrupt the free flow of maritime trade on which the country’s economic prosperity depends, and, second, that if China is able to persuade or coerce other Asian nations into accepting its claimed ‘historic rights’ in the South China Sea, existing international legal norms would be undermined. Moreover, Tokyo is alarmed at China’s increasingly assertive posture in the maritime domain, and views the disputes in the South and East China Seas as linked. To mitigate its concerns over the South China Sea, Japan is pursuing a number of strategies: it raises the problem at regional security forums; it seeks to enhance cooperation with the Association of Southeast Asian Nations on issues of maritime security and encourage unity within the organization on the South China Sea; it discusses the problem bilaterally with Southeast Asian countries and has started to provide capacity-building support to selected claimants (principally, the Philippines); and it seeks closer ties with other external stakeholders that share its concerns.

Coral species inventory at War in the Pacific National Historical Park: Final report

The South China Sea in the Central Indo-Pacific is a large marine region that spans an area of more than 3 million km2 bounded by the coastlines of ten Asian nation states and contains numerous small islands. Although it abuts the western border of the Coral Triangle, the designated centre of maximum marine biodiversity, the South China Sea has received much less scientific and conservation attention. In particular, a consolidated estimate of the region’s scleractinian reef coral diversity has yet to emerge. To address this issue, we assemble a comprehensive species distribution data set that comprises 16 reef areas spread across the entire South China Sea. Despite containing less than 17 % of the reef area as compared to the Coral Triangle, this region hosts 571 known species of reef corals, a richness that is comparable to the Coral Triangle’s based on a standardised nomenclatural scheme. Similarity profile analysis and non-metric multidimensional scaling demonstrate that most areas are compositionally distinct from one another and are structured according to latitude but not longitude. More broadly, this study underscores the remarkable and unexpected diversity of reef corals in the South China Sea.

Signals, Deterrence, and the Quad Ketian Zhang (bio) The United States and its allies have the capability to deter China, and have successfully done so, from their worst-case scenario—a major militarized conflict. However, three factors reduce the effectiveness of their deterrence: the lack of clear signals, excessive media exposure, and divergent interests among Quad members. The Quad can be useful, but only if the United States maintains well-defined signals of commitment while clarifying the stakes. As it currently stands, the Quad does not successfully deter Chinese actions in territorial disputes. China has not shied away from using military coercion in its land border disputes with India. In June 2020, for instance, Chinese and Indian troops clashed violently along the disputed land border in the Galwan Valley, resulting in casualties on both sides.1 Chinese foreign minister Wang Yi told India to "stop transgressions into China-controlled territories" and to "refrain from actions changing the status quo along the border," representing a clear indication of coercive intent.2 Moreover, although China prefers to utilize nonmilitary—or so-called gray-zone—coercion in maritime disputes in the South and East China Seas, such coercive measures can themselves be destabilizing.3 This essay assesses factors influencing the likelihood of successful deterrence in the Indo-Pacific region by using China's land and maritime territorial disputes as examples. It addresses two questions: what signals of resolve are necessary for effective deterrence, and does the Quad enhance [End Page 43] deterrence? Finally, it uses the Sino-Indian border and South China Sea disputes to illustrate the conditions under which deterrence can be effective. The Need for Clearer Signals The United States and its allies have the capability to potentially deter China's territorial challenges. However, clearer signals of resolve and reassurance are necessary to achieve successful deterrence. First and foremost, the United States should set clearer red lines; otherwise, the signals sent to China are mixed and ineffective. For example, during its first term, the Obama administration was not sufficiently clear in signaling red lines to China regarding Chinese behavior in the South China Sea. A 2013 Chinese Academy of Social Sciences report on China's regional security environment stated that the implementation of U.S. rebalancing "had a problem of divergence between willingness and capability," citing the lack of U.S. commitment during the Scarborough Shoal incident of April 2012.4 This lack of clear U.S. red lines led Beijing to proceed with large-scale land reclamation activities in late 2013 and 2014. One Chinese scholar this author interviewed who was often in conversation with the then South China Sea section of China's State Oceanic Administration noted that "China first started reclamation at the Johnson South Reef and was watching the reaction from the international society carefully; it proceeded with large-scale reclamation after realizing that there was not much of a reaction internationally."5 By "international," this interviewee meant the United States. The U.S. response in 2014 was relatively muted: Washington did not call out China's land reclamation from the outset. Instead, the White House and, importantly, President Barack Obama himself remained silent. Obama's second term, however, saw the drawing of clearer red lines. During the November 2015 Asia-Pacific Economic Cooperation (APEC) summit in Manila, Obama called on China to halt its land reclamation activities in the South China Sea.6 He subsequently warned Beijing in March 2016 that there would be "serious consequences if China reclaimed land [End Page 44] at the Scarborough Shoal."7 Local Chinese government documents from 2013 noted explicitly that China would implement land reclamation on the Scarborough Shoal.8 Yet following Obama's 2015–16 warnings, subsequent government documents cease to mention reclamation on the Scarborough Shoal. This suggests that without the clear red line from the United States, it is quite plausible that China would have proceeded to reclaim the Scarborough Shoal, making this episode a successful case of U.S. deterrence. The Trump administration pressed Beijing to halt militarization of the South China Sea, but Trump himself did not issue a clearly stated red line. This lack of clarity could have had adverse effects. Chinese analyst...

Abstract:
 This article analyses the four main military strategies of the People's Republic of China toward the South and East China Seas Security architecture under President Xi Jinping. These strategies of Beijing have been applied mainly to the region, which has been under the US alliance system's security umbrella since the Cold War. The article demonstrates that the People's Republic of China, under the leadership of Xi Jinping, seeks to reorder the regional security architecture to its favour by leveraging military modernization, influence operations, and diplomatic-economic power to push out the US and allies’ countries' influence outside East and South China Seas. This article argues that the successful conclusion of the rising power's strategies over the East and South China seas will translate the current geopolitical rivalry to result in a power transition to the detriment of the rising power.
 Keywords: China, Xi Jinping, East China Sea, South China Sea, Power Transition

This article reviews the coral diversity and coral reef environment in Brunei Darussalam, in comparison with the other regions in the South China Sea (SCS). Extensive surveys on corals had not been conducted in Brunei Darussalam for a long time but the recent efforts of coral identification have revealed that approximately 400 species of scleractinian corals inhabit in Brunei seawaters, which is close to the highest diversity in the SCS. The most dominant coral family in species number was Acroporidae, which accounted for 30% of the whole coral species. Using the published data on coral diversity in the SCS, multivariate analyses showed that the number of coral species in any tested coral familiy (Acroporidae, Agariciidae, Fungiidae, Lobophylliidae, Merulinidae, and Poritidae) in a region was significantly correlated with the total number of coral species in the region, indicating that the coral diversity in any family reflects the coral diversity in the whole ecosystem. Although the high coral diversity was confirmed in Brunei Darussalam, several threats to corals have also been reported. Regular monitoring of the coral reef status is required to promptly detect undesirable environmental changes in the future.