Hurricanes and coral bleaching linked to changes in coral recruitment in Tobago

Knowledge of coral recruitment patterns helps us understand how reefs react following major disturbances and provides us with an early warning system for predicting future reef health problems. We have reconstructed and interpreted historical and modern-day recruitment patterns, using a combination of growth modelling and in situ recruitment experiments, in order to understand how hurricanes, storms and bleaching events have influenced coral recruitment on the Caribbean coastline of Tobago. Whilst Tobago does not lie within the main hurricane belt results indicate that regional hurricane events negatively impact coral recruitment patterns in the Southern Caribbean. In years following hurricanes, tropical storms and bleaching events, coral recruitment was reduced when compared to normal years (p = 0.016). Following Hurricane Ivan in 2004 and the 2005–2006 bleaching event, coral recruitment was markedly limited with only 2% (n = 6) of colonies estimated to have recruited during 2006 and 2007. Our experimental results indicate that despite multiple large-scale disturbances corals are still recruiting on Tobago’s marginal reef systems, albeit in low numbers.     

The importance of extratropical and tropical cyclones on the short-term evolution of barrier islands along the northern Gulf of Mexico, USA

Data are presented indicating the complexity and highly variable response of beaches to cold front passages along the northern Gulf of Mexico, in addition to the impacts of tropical cyclones and winter storms. Within the past decade, an increase in the frequency of tropical storms and hurricanes impacting the northern Gulf has dramatically altered the long-term equilibrium of a large portion of this coast. A time series of net sediment flux for subaerial and nearshore environments has been established for a section of this coast in Florida, and to a lesser extent, Mississippi. The data incorporate the morphological signature of six tropical storms/hurricanes and more than 200 frontal passages.

Data indicate that (1) barrier islands can conserve mass during catastrophic hurricanes (e.g., Hurricane Opal, a strong category 4 hurricane near landfall); (2) less severe hurricanes and tropical storms can promote rapid dune aggradation and can contribute sediment to the entire barrier system; (3) cold fronts play a critical role in the poststorm adjustment of the barrier by deflating the subaerial portion of the overwash terrace and eroding its marginal lobe along the bayside beach through locally generated, high frequency, steep waves; and (4) barrier systems along the northern Gulf do not necessarily enter an immediate poststorm recovery phase, although nested in sediment-rich nearshore environments. While high wave energy conditions associated with cold fronts play an integral role in the evolution and maintenance of barriers along the northern Gulf, these events are more effective in reworking sediment after the occurrence of extreme events such as hurricanes. This relationship is even more apparent during the clustering of tropical cyclones.

It is anticipated that these findings will have important implications for the longer term evolution of barrier systems in midlatitude, microtidal settings where the clustering of storms is apparent, and winter storms are significant in intensity and frequency along the coast.     

Characteristics of Landfalling Tropical Cyclones in North Carolina

Trends in the Atlantic tropical cyclones and the cyclones that had tracks through North Carolina were analyzed for more than 100 years. From about 1970, there appears to be an increase in the mean number of storms developing. The number of storms affecting North Carolina each decade has been increasing since the 1960s. In the 1980s, 1990s, and into the 2000s, there was an increase in the number of landfalling storms in North Carolina. Although August and September are the most active months of the Atlantic hurricane season, the hurricane season for North Carolina peaks in September. Wind distribution and frictional convergence associated with landfalling hurricanes in North Carolina are discussed. Convection and precipitation patterns of landfalling hurricanes are presented. Two examples of the effect of spatial surface moisture distribution on intensification of tropical cyclones over land after landfall are discussed.     

海南铜鼓岭国家级自然保护区海域珊瑚的分布及其健康状况评价

沿铜鼓岭国家级自然保护区海岸南北两侧沿岸布设8个站位,采用断面监测法调查了珊瑚的种类多样性、覆盖率、死亡率和补充量等指标,并利用健康指数（CI）评估了铜鼓岭珊瑚礁生态系统的健康状况和遭受环境压力的程度.本次调查共发现铜鼓岭造礁石珊瑚11科23属40种,软珊瑚8种,造礁石珊瑚和软珊瑚覆盖率分别为13.8%和19.4%,该海域珊瑚礁生态系统保存较为完好和健康.铜鼓岭珊瑚的覆盖率呈现明显的空间分布特征,北侧珊瑚覆盖率为0.1%～9.8%之间,远低于南侧的水平（8.1%～66.1%）.从珊瑚补充量来看,铜鼓岭北侧珊瑚的恢复能力基本为零,而铜鼓岭以南的区域可以有0.4个/m^2珊瑚新个体.通过比较2006年以来珊瑚种类、覆盖率、死亡率、补充量、健康指数等方面的调查数据,认为铜鼓岭保护区的珊瑚礁生态系统得到有效保护,珊瑚礁生态系统处于健康状态.     

南沙永暑礁表层珊瑚年代结构及其环境记录

南沙群岛永暑礁7个表层礁坪原生块状珊瑚的高精度TIMS U-Th和12个常规^14C测年结果表明,永暑礁表层礁坪形成于现代,与钻探研究结果吻合。全新世永暑礁系从约7300aBP开始,以现代礁坪面以下17m左右的晚更新世礁灰岩为基底连续发育至今,因此,与南海周边地区的珊瑚礁不同,南沙群岛珊瑚礁的表层块状珊瑚不能够提供全新世高海平面的证据。由于现代珊瑚礁的堆积速率大于地壳沉降速率,可能会形成更多的灰沙洲或灰沙岛。     

A review of the climatological characteristics of landfalling Gulf hurricanes for wind, wave, and surge hazard estimation

The climatological characteristics of landfalling Gulf of Mexico hurricanes are presented, focusing on the basic parameters needed for accurately determining the structure and intensity of hurricanes for ocean response models. These include the maximum sustained wind, radius of maximum winds, the Holland-B parameter, the peripheral or far-field pressure, the surface roughness and coefficient of drag, and the central pressure for historical hurricanes in the Gulf.Despite evidence of a slight increase in the annual number of named storms over the past 50 years, presently there is no statistically significant trend in tropical storms, hurricanes, or major hurricanes in the Gulf of Mexico. In addition, the long-term variability of tropical cyclones in the Gulf reflects the observed variability in the Atlantic basin as a whole. Analyses of hurricane winds from multiple sources suggest the presence of a bias toward overestimating the strength of winds in the HURDAT dataset from 7% to 15%. Results presented comparing HURDAT with other sources also show an overestimation of intensity at landfall, with an estimated bias of ~10%.Finally, a review of recent studies has shown that hurricane frequencies and intensities appear to vary on a much more localized scale than previously believed. This exacerbates the sampling problem for accurate characterization of hurricane parameters for design and operational applications.     

大亚湾及大鹏半岛沿岸造礁石珊瑚现状与生态脆弱性评价

本研究于2020年7月在大亚湾及大鹏半岛沿岸开展造礁石珊瑚的分布、覆盖率、死亡率、硬珊瑚补充量和物种多样性调查。结果表明：24个站位共发现造礁石珊瑚9科17属44种以及5个未定种,其中裸肋珊瑚科的种类最多,有7属27种,其次为鹿角珊瑚科和滨珊瑚科,均有2属6种;中央列岛沿岸造礁石珊瑚平均覆盖率为12.0%,三门岛沿岸平均覆盖率为12.9%,大鹏半岛沿岸平均覆盖率为5.2%;以坚实滨珊瑚（Porites solida）、翼形蔷薇珊瑚（Montipora peltiformis）、五边角蜂巢珊瑚（Favites pentagona）和多孔同星珊瑚（Plesiastrea versipora）等为优势种;造礁石珊瑚物种多样性较高。与历史数据相比,大亚湾及大鹏半岛沿岸造礁石珊瑚退化严重,活珊瑚覆盖率锐减,优势种由分支状珊瑚逐步转变为皮壳状或亚团块状珊瑚。此外,本研究构建了近岸造礁石珊瑚生态脆弱性评价体系,并对目前大亚湾及大鹏半岛沿岸造礁石珊瑚进行了生态脆弱性评价。结果显示,中央列岛、三门岛和大鹏半岛东侧海域造礁石珊瑚处于低或中脆弱状态;较场尾、杨梅坑、西冲和大鹏半岛西侧海域造礁石珊瑚处于高或很高脆弱状态,在环境压力影响下其受损可能性较高。在海水养殖、渔业捕捞、滨海旅游和船舶航行等日益频繁的人类活动下,大亚湾及大鹏半岛沿岸造礁石珊瑚整体处于中高脆弱状态,建议加强珊瑚礁监测,并采取相应的保护措施。     

涠洲岛珊瑚礁近千年的发育过程及其对气候变化的响应*

高纬度珊瑚栖息地能否成为气候变暖背景下热带珊瑚物种的“避难所”仍不明确, 南海北部的相关研究更是稀少。本文以取自涠洲岛的2根珊瑚礁沉积岩心为研究对象, 通过U-Th定年、沉积组分分析以及珊瑚种属鉴定等方法, 探讨近千年以来珊瑚礁的发育过程及其对气候变化的响应。研究结果发现, Core1(石螺口)岩心沉积的3个快速堆积阶段分别与罗马暖期、中世纪暖期和现代暖期大致对应; 而2个缓慢堆积阶段则分别与黑暗时代冷期和小冰期大致对应, 证实了温暖的气候对珊瑚礁发育有促进作用, 而寒冷的气候则不利于珊瑚礁的发育; 此外, 现代强烈的人为干扰可能也导致了涠洲岛珊瑚礁的迅速退化。Core2(南湾)中陆源沉积含量高, 珊瑚年龄主要集中在800AD—950AD和现代这两个时间段内, 其原因可能与环境变化、风暴作用及湾内现代珊瑚分布特征有关。通过对比这两个站位的珊瑚礁沉积特征, 本文进一步提出“完全避难所”和“非完全避难所”的概念, 揭示涠洲岛珊瑚可能同时具有低纬度热带珊瑚礁和高纬度珊瑚群落这两种发育特征和趋势。     

Scleractinian coral population size structures and growth rates indicate coral resilience on the fringing reefs of North Jamaica

Coral reefs throughout the world are under severe challenges from many environmental factors. This paper quantifies the size structure of populations and the growth rates of corals from 2000 to 2008 to test whether the Discovery Bay coral colonies showed resilience in the face of multiple acute stressors of hurricanes and bleaching. There was a reduction in numbers of colonies in the smallest size class for all the species at all the sites in 2006, after the mass bleaching of 2005, with subsequent increases for all species at all sites in 2007 and 2008. Radial growth rates (mm yr⁻¹) of non-branching corals and linear extension rates (mm yr⁻¹) of branching corals calculated on an annual basis from 2000–2008 showed few significant differences either spatially or temporally. At Dairy Bull reef, live coral cover increased from 13 ± 5% in 2006 to 20 ± 9% in 2007 and 31 ± 7% in 2008, while live Acropora species increased from 2 ± 2% in 2006 to 10 ± 4% in 2007 and 22 ± 7% in 2008. These studies indicate good levels of coral resilience on the fringing reefs around Discovery Bay in Jamaica.     

全球变化背景下暖水珊瑚礁生态系统的适应性与修复研究

暖水珊瑚礁生态系统是热带海域最具生物多样性和代表性的生态系统之一。本研究分析了全球变化背景下暖水珊瑚礁生态系统的变化和风险,开展了受损暖水珊瑚礁生态系统退化和消失的致灾因子归因分析,综述了暖水珊瑚礁生态系统的适应性与修复技术研究。分析表明:①过去几十年来,暖水珊瑚礁生态系统快速退化,包括大面积白化和死亡、多样性明显减少和生态功能显著衰退,主要归因于海洋升温与人类活动等致灾因子的影响;②在温室气体高排放浓度情景下(RCP 8.5),相比工业革命前,到本世纪中叶,南海升温将可能远超过2℃,这表明南海暖水珊瑚礁生态系统正在逼近其气候临界点,即全球升温高于2℃时,90%~99%以上的暖水珊瑚将消失;③1980年代以来,海洋升温、海洋热浪和强热带气旋等海洋气候变化致灾因子对南海暖水珊瑚的危害性(影响的强度、范围和时间)明显增加,对暖水珊瑚礁生态系统产生了严重的影响;与此同时,近岸海域的过度或破坏性捕捞、采挖和潜水等人类活动,对暖水珊瑚造成了严重损害,增加了暖水珊瑚的气候脆弱性,而这种人类活动既是局部的,也是全球性的现象,使得暖水珊瑚更难以适应全球变暖的影响。分析还表明,为了增强暖水珊瑚适应气候与环境变化的恢复力(韧性),人们开展了诸多受损珊瑚礁生态系统的适应性与修复研究,但主要是采用无性繁殖或结合人工基质的修复方式,而应用有性繁殖技术恢复受损珊瑚礁的方式仍较少;最近,暖水珊瑚耐热的基因适应性研究取得了重要进展,为暖水珊瑚适应全球变暖提供了一种新的途径。本研究最后探讨了中国受损珊瑚礁生态系统的修复问题与对策。     

Biodiversity,ecological structure,and change in the sponge community of different geomorphological zones of the barrier fore reef at Carrie Bow Cay,Belize

Changes in the relative abundance of benthic groups on the barrier fore reef at Carrie Bow Cay, Belize, point to a significant reduction of corals and an expansion of the sponge community in 1995–2009. Fifty‐one species are now present in the four geomorphological zones of this reef: the low‐relief spur‐and‐groove zone, the inner reef slope, the outer ridge, and the fore‐reef slope (to a depth of 30 m). Five species are new additions to the sponge fauna reported for Belize, and six species account for 42.6% of the total assemblage: Niphates erecta (9.60%), Aiolochroia crassa (8.8%), Niphates digitalis (6.9%), Callyspongia plicifera (6.63%), Aplysina archeri (5.37%) and Xestospongia muta (5.37%). Species richness, average density, diversity and evenness indexes are statistically similar in these four zones but some species appear to be more dominant in certain areas. In the same 30 years, coral cover has decreased by more than 90%, while the octocoral cover has greatly increased (by as much as 10‐fold in the low‐relief spur‐and‐groove zone). Thus the Carrie Bow fore reef appears to be undergoing a transition from coral dominance in the late 1970s to algae dominance today, with other benthic groups such as sponges and octocorals showing signs of gradual recovery.     

Working up an appetite for lionfish: A market-based approach to manage the invasion of Pterois volitans in Belize

Located on the Caribbean coast of Central America and flanked by the second longest barrier reef in the world, Belize is a nation reliant upon marine resources. Each year, the country’s predominantly small-scale fisheries generate an estimated US$22 million in revenue – 1.8%of GDP – and employ 3000 people. However, the nation’s fishing communities are facing an unprecedented challenge. Existing threats posed by declining fish stocks have been exacerbated by the introduction of the invasive alien red lionfish Pterois volitans in 2008. This Indo-Pacific predator has the potential to cause significant losses to the recruitment of native fish, in turn disrupting coral reef community dynamics in the Belize Barrier Reef Reserve System, a UNESCO World Heritage Site. Howefver, targeted lionfish fishing may offer a cost effective means to control the invasion, while also creating an alternative livelihood solution and improving food security among Belize's coastal fishing communities. This study summarises the recent history of the lionfish invasion in Belize, describes the multi-sector approach being used to address the invasion, and presents preliminary research summarising the characteristics of invasive alien lionfish in Belize. Data from Belize's nascent ‘lionfishery’ are also presented, demonstrating that demand for lionfish is outweighing supply – largely as a result of awareness-raising initiatives – and highlighting the strong potential for replication of this approach elsewhere in the Caribbean. The study concludes by discussing the barriers and potential solutions to this market-based approach to invasive species management.     

A backbarrier overwash record of intense storms from Brigantine, New Jersey

Analysis of aerial photographs and historic charts indicates that the barrier beach at Brigantine, NJ has migrated landward 300 to 400 m since 1869, primarily as a result of overwash during hurricanes and winter storms. A series of vibracores from the backbarrier salt marsh reveals a millennial-scale stratigraphic record of overwash deposition. Carbon-14 (C-14) and Cesium-137 (Cs-137) radioisotopic methods were used to date overwash deposits (washovers). The ages of recent washovers are consistent with deposition during intense storms in 1938, 1944, 1950, and 1962. An additional overwash deposit recovered in five of the sediment cores was likely deposited by an intense hurricane strike in 1821 or possibly in 1788. Two prehistoric overwash fans were likely deposited by intense storms striking the New Jersey Coast in the 7th to 14th centuries and 6th to 7th centuries A.D. The landward barrier migration indicates that the older overwash sediments were likely transported a considerably greater distance than the more recent overwash fans. The greater distance of transport may indicate that the prehistoric storms that deposited overwash fans across the study site were more intense than the most intense storm to strike this coast in the historic period, the hurricane of 1821. The spatially variable occurrence of overwash deposition at this site points to a need for multisite stratigraphic surveys of extensive stretches of the coast in order to develop reliable records of past intense storm frequency from backbarrier environments.     

涠洲岛西南部海域造礁石珊瑚的群落结构特征分析

采用2019年5月14?22日开展的断面法调查数据,分析了涠洲岛西南部海域的造礁石珊瑚群落结构特征。结果表明:涠洲岛西南部海域造礁石珊瑚共有9科38种,优势种为滨珊瑚(Porites sp.)、秘密角蜂巢珊瑚(Favites abdita)、斯氏角孔珊瑚(Goniopora stutchburyi)等团块状珊瑚。活造礁石珊瑚覆盖率为5.20%～31.20%,平均值为16.66%,远离海岸或靠近海岸但水较深的站位覆盖率较高。石珊瑚补充量较低、病害少、死亡率较低。造礁石珊瑚群落的物种多样性、优势度、均匀度互相呈显著正相关关系(p<0.05)。靠近岩壁的站位,水较深且船舶通行和游客潜水等影响较少,活造礁石珊瑚覆盖率和多样性程度均较高。受侵蚀海岸悬浮泥沙和潜水旅游影响较大的砂质岸段站位,活造礁石珊瑚覆盖率最低、优势种的优势度最高、多样性程度相对较低。人为活动、西南季风、风暴潮、海岸侵蚀悬沙、极端气候是影响涠洲岛西南部海域造礁石珊瑚礁生态系统的主要因素。     

Stability of reef framework and post settlement mortality as the structuring factor for recovery of Malakal Bay Reef,Palau, Micronesia: 25 years after a severe COTS outbreak

Corals in Malakal Bay reefs were devastated in the 1979 Crown of Thorns Starfish (COTS) outbreak. It has been almost 30 years since the outbreak and coral cover at the study sites have not come close to the cover before the outbreak. A question is asked: what factors may contribute to the slow recovery of these reefs: recruitment or post-settlement mortality? Two habitat types within the reef systems were monitored using coral transplants to determine if corals can survive in these environments and recruitment tiles to see if there are larvae coming into the system. The study revealed that coral survivorship is high in the fore reef areas compared to the reef channel slopes and that larvae is not a limiting factor to natural recovery. Stability of the reef framework, i.e. unstable rubble substrate, and possibly high post settlement mortality, are the structuring factors that determine the recovery process in these reef systems and possibly so for similar habitats in other reef systems throughout Palau.     

Current trends of space occupation by encrusting excavating sponges on Colombian coral reefs

Some sponges of the genus Cliona (Porifera, Hadromerida, Clionidae) simultaneously excavate and encrust calcareous substratum, competing aggressively for illuminated space with corals and other organisms. To interpret current trends of reef space occupation, the patterns of distribution and size of three Caribbean species were examined at San Andrés Island and Islas del Rosario in Colombia. While Cliona aprica was ubiquitous, C. caribbaea (= C. langae) preferred deep and protected reef zones, and C. tenuis shallow and wave‐exposed settings. In contrast to the effect on other excavating sponges, chronic exposure to raw sewage did not significantly increase the abundance of the studied sponges. Substratum occupation/availability ratios showed a positive tendency of the sponges toward certain coral skeletons, and a negative or neutral tendency toward calcareous rock, indicating that establishment may be easier on clean, recently dead coral than on older, heavily incrusted substratum. High relief generally limits sponge size to that of the illuminated portions of the substratum. A generally lower proportion of small individuals than of larger ones indicates currently low recruitment rates and low subsequent mortality. Successful events of higher recruitment seem to have occurred for C. tenuis. These are related to the massive acroporid coral die‐off in the early 1980s and to asexual dispersion during storms, resulting in a current 10% substratum cover. Reefs with high coral mortality were and/or are thus more susceptible to colonization and subsequent space occupation by these sponges, although relief may prevent space monopolization.     

全球变暖背景下三亚湾上升流的冷水有利于珊瑚的生存

It has been reported that global warming has negative effects on coral ecosystems in the past 50 years and the effects vary in different ocean environment. In order to make clear the coral reef status in the background of global warming along the south coast of Hainan Island of China, satellite and in situ data are used to retrieve the information of the coral reef status and surrounding environmental factors. The results show that cool water induced by upwelling along the south coast of Hainan Island is found in the area every summer month, especially in the relatively strong El Ni?o years(2002–2003 and 2005). From the NOAA satellite data, degree heating week(DHW) index does not exceed 3 in Sanya Bay even in the relatively strong El Ni?o years. By comparison of a coral reef growth rate in the Sanya Bay with respect to El Ni?o events from 1957 to 2000, coral's growth rate is relatively greater during 1972, 1991–1994 and 1998 El Ni?o event. By analyzing the environmental factors, it is found that the cool water induced by upwelling may be the main reason for protecting corals from global warming effects.     

Long-term impacts of coral bleaching events on the world's warmest reefs

The southern Arabian Gulf houses some of the most thermally tolerant corals on earth, but severe bleaching in the late 1990s caused widespread mortality. More than a decade later, corals still dominated benthos (mean: 40 ± 3% cover on 10 sites spanning > 350 km; range: 11.0-65.6%), but coral communities varied spatially. Sites to the west generally had low species richness and coral cover (mean: 3.2 species per transect, 31% cover), with Porites dominated communities (88% of coral) that are distinct from more diverse and higher cover eastern sites (mean: 10.3 species per transect, 62% cover). These patterns reflect both the more extreme bleaching to the west in the late 1990s as well as the higher faviid dominated recruitment to the east in subsequent years. There has been limited recovery of the formerly dominant Acropora, which now represents <1% of the benthos, likely as a result of recruitment failure. Results indicate that severe bleaching can have substantial long-term impacts on coral communities, even in areas with corals tolerant to environmental extremes.     

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.     

典型近岸退化珊瑚礁的成功修复案例——蜈支洲珊瑚覆盖率的恢复

在全球珊瑚礁生态系统面临退化威胁的情况下,珊瑚礁生态修复工作成为人类帮助珊瑚礁恢复健康的重要手段之一,并且在全球各个珊瑚礁区域都得到广泛应用.我国近岸珊瑚礁生态系统退化严重,本实验探讨利用珊瑚移植技术在三亚市蜈支洲岛典型的近岸珊瑚礁环境下恢复造礁石珊瑚的覆盖率,希望推动企业参与海洋生态保护并从中受益.在与当地旅游公司的...