Coral Recruitment and Regeneration on a Maldivian Reef 21 Months after the Coral Bleaching Event of 1998

Abstract. This paper describes the quantitative inventory of stony corals on a Maldivian reef after the bleaching event of 1998. The detailed data, collected in March 1999 and March 2000, comprise survival, new recruitment and regenerates. They were obtained in 6 transects laid out randomly on the reef flat, on 22 Acropora tables on 6 sites at the reef edge and on 39 Porites lobata blocks and 1 Diploastrea heliopora colony. The present cover of living zooxanthellate corals is reduced to ca. 2 – 5 % of its previous state. Acroporidae and Pocilloporidae were practically wiped out, while Poritidae survived partly and Agariciidae (esp. Pavona) are now the dominant group. New settlements on dead Acropora tables were mainly Agariciidae, followed by Acroporidae and Pocilloporidae. Regenerates on Porites were pronounced and the apparent yearly increase in mass was about threefold that of Diploastrea, which is 3 – 4 mm per year. The influence on reef ecology in terms of coral substrate and species, possible sources of larvae, change of guilds in reef builders, other species and the prospect for further development of the reef, with respect to growth versus erosion, is discussed.     

The Skeleton Eroding Band Disease on Coral Reefs of Aqaba, Red Sea

Abstract.  The occurrence and distribution of the coral disease Skeleton Eroding Band (SEB) has been studied at the Jordanian coast in the Gulf of Aqaba, the northernmost extension of the Red Sea. The SEB syndrome is caused by the colonial, heterotrich ciliate Halofolliculina corallasia : an advancing front of these protists destroys polyps, coenosarc, and surface of the coenosteum. In recent years SEB was registered in reefs of Australia, Mauritius, and the Red Sea. Along the Jordanian coast, disease frequency at four study sites was investigated and afflicted coral genera and species were documented. The study sites were MSS (Marine Science Station)-north, MSS-south, the tourist area near the middle of the coast, and the industrial area adjacent to the Saudi Arabian border. Corals and infections were counted inside randomly placed 1 m² frames in reef flats and in 5, 10, and 15 m depths. In order of increasing affectedness of sample sites, MSS-south was the healthiest (12%, 4%, 4%, 16% of infected corals from shallow to deep), followed by MSS-north (19%, 28%, 24%, 24%), the tourist area (51%, 23%, 16%, 41%), and the industrial area (14%, 30%, 39%, 31%). By far the most frequently encountered coral species were Acropora spp. and Stylophora sp., while relative infection-rates were highest among Seriatopora sp. (75%), as well as Stylophora sp., Hydnophora sp., and Galaxea sp. (50% each). This was followed in steadily decreasing order from 44% to 5% by Pocillopora , Mycedium , Montipora , Echinopora , Acropora , Lobophyllia , Goniastrea , Millepora , Platygyra , Fungia , Favia , Porites , Goniopora , Favites , and Pavona . SEB was found to a depth of 30 m, but may occur even deeper.     

Coral Reef Community Structure at Caño Island, Pacific Costa Rica

Abstract. Around the Biological Reserve of Caño Island, Pacific Costa Rica, there are five large coral reef flats (with size ranges of 0.8–4.2 ha) built mainly of dead Pocillopora spp. At present, they are covered mainly by crustose coralline algae and microatolls of Porites lobata . From the upper reef slope to the reef base several corals grow in small patches (e. g., Pavona clavus, Pavona varians, Pavona gigantea, Gardineroseris planulata, Psammocora superficialis, Pocillopora elegans, Pocillopora damicornis); the massive coral Porites Iobata is predominant. Pocilloporid species are predominant on most other eastern Pacific reefs.
The Caño Island reef is typical of a community whose structure has been controlled by both physical (in shallow water) and biological (in deeper water) factors. Shallow reef areas are influenced by strong wave action and extreme low tides. The distribution, abundance, and feeding preferences of corallivorous organisms (e. g., Acanthaster planci, Arothron meleagris, Pseudobalistes naufragium, Quoyula monodonta) on the deeper reef suggest that most pocilloporids are affected and limited by them. Although there is no evidence of any predator on Porites lobata at Caño Island, the triggerfish Pseudobalistes naufragium breaks off fragments of the coral while searching for food. These fragments often survive to form new colonies. Together, this dispersal mechanism, rapid injury recovery, and high resistance to environmental stress seem to enhance the distribution and dominance of the massive coral Porites lobata at Caño Island.     

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.     

The Structure of Coral Communities at Hurghada in the Northern Red Sea

Abstract. The community structure of hard and soft corals, with an emphasis on hard corals, was determined by means of line-transects on 9 on-and off-shore reefs of different type and different wave exposure in the Northern Red Sea near Hurghada in Egypt. Coral communities were found to differentiate along a horizontal wind- and wave-exposure gradient. Exposed communities were dominated by Acropora species, sheltered communities by Porites species, and semi-exposed communities by Millepora species. Also, vertical within-reef zonations following a depth gradient were observed; these were unique for each exposure-determined community type. Average transect diversity was highest on semi-exposed reefs, lowest on sheltered reefs. Reef slopes were more diverse than other reef zones. The observed community structure was compared with data from the literature, and widely distributed, roughly comparable hard and soft coral communities were identified.     

Abundance and Photosynthetic Characteristics of Trichodesmium spp. Along the Atlantic Barrier Reef at Carrie Bow Cay, Belize

Abstract. Trichodesmium abundance and photosynthetic rates were determined across a transect of the Atlantic Barrier Reef at Carrie Bow Cay, Belize in May 1993 and May-June 1994. A fore reef station receiving oceanic water had a Trichodesmium abundance characteristic of the open Caribbean Sea (≤ 10² colonies m^-3 and 10⁴-^-10⁵ trichomes m^-3). Several species were present; however, in all cases a sharp decrease in abundance occurred across the reef to the coastal lagoon. At this latter site, virtually no Trichodesmium was present, although a substantial bloom of the diatom Proboscia alata occurred in 1994.
Maximum photosynthetic rates and the initial light-limited slope a were significantly lower in offshore stations than in reef top populations. The increased photosynthetic rates and light-harvesting ability in reef-top populations, as well as the lack of significant photoinhibition, indicated that the Trichodesmium abundance decrease was probably not due to a decline in photosynthetic capacity. Grazing and physical removal rather than a physiological decline were likely mechanisms operating to reduce Trichodesmium abundance in these regions. These data suggest that the Belizean barrier reef is a sink for Trichodesmium transported in from offshore regions.     

Population Density, Distribution and Consumption Rates of Three Corallivores at Cabo Pulmo Reef, Gulf of California, Mexico

Abstract. The influence of corallivores on coral community structure of eastern Pacific reefs has been considered less important then that of abiotic oceanographic factors. The data that support this assumption, however, are only available for Central American reefs. To assess the role of predation on hermatypic corals in a different regional reef environment, the abundance, spatial distribution and consumption rate of three corallivores: the echinoid Eucidaris thouarsii (Valenciennes), the asteroid Acanthaster planci (Linnaeus) and the teleostean fish Arothron meleagris (Bloch & Schneider), were estimated at Cabo Pulmo reef, Gulf of California, México (23°25' N, 109°25' W). Statistically, the abundances of the species did not change in any sections of the reef (mean values: E. thouarsii , 0.17 indiv. · m⁻²; A. planci , 1.9 indiv. · m⁻²; A. meleagris , 39 indiv. · ha⁻¹). The average daily individual consumption rates of coral were calculated at 1.83 g CaCO₃· m⁻² for E. thouarsii , 118.4 cm² for A. planci , and 16.38 g CaCO₃· m⁻² for A. meleagris , and were lower than those reported for Central American reefs. Considering the mean estimated carbonate production (7.9 kg CaCO₃· m⁻²· a⁻¹), corallivores eliminate less than 4% of the coral standing stock of Cabo Pulmo reef. The low corallivore population density and consumption rates, together with high local coral cover, indicate that corallivores are not key factors determining scleractinian abundance in this marginal reef.     

海南西岛珊瑚群落变化及其影响因素 *

在2018年的海南三亚西岛珊瑚群落分布和水质环境因子调查中, 共记录到造礁石珊瑚68种, 多孔螅2种。基于珊瑚礁底质类型的非度量多维标度分析, 可将西岛站位划分为区域1(东-南侧)和区域2(西侧)。全岛活珊瑚覆盖率为13.6%, 区域1和区域2分别为4.2%和27.7%, 区域2珊瑚多样性高于区域1。区域1珊瑚礁处在显著退化状态, 而区域2相对健康, 但是优势种类单一。与历史资料对比分析, 东侧站位造礁石珊瑚覆盖率从2011年的近40%降至2018年不足4%, 退化显著, 而西侧站位珊瑚礁无明显退化; 丛生盔形珊瑚(Galaxea fascicularis)逐渐取代分枝状的鹿角珊瑚成为绝对优势种类; 珊瑚礁区浊度、溶解无机氮(dissolved inorganic nitrogen, DIN)和喇叭藻的δ¹⁵N均值分别为2.54NTU、9.63μmol·L^-1和5.09‰, 均处在较高水平。相关性分析表明, 环境因子的空间变化并不能解释珊瑚群落的空间分布。因此, 推测人类活动引起的极端扰动事件可能是导致西岛珊瑚群落空间分布和东侧站位珊瑚近几年显著退化的主要原因, 如三亚河清淤在三亚湾随意倾倒引起的浑浊事件。应加强对三亚湾清淤和西岛人类活动的管控, 减轻颗粒物沉积和营养盐富集的影响, 促进西岛珊瑚礁逐渐恢复。     

Characteristics of Growth Rate of Coral Porites from Sanya Bay, Hainan Island and its Relationship to Environmental Variables

The time series of annual and seasonal growth rate of two coral Porites, collected at different sites of fringe reef in the Sanya Bay, Hainan Island have been obtained by analyzing X-radiograph of skeletal band. There are obvious seasonal variations of the growth rate in two corals, the average low rate in winter and the average high rate from spring to autumn. Compared with the time series of environmental variables, the coral growth rote is only correlated statistically with seawater temperature and not related to rainfall and sunshine. Furthermore, the growth rate in spring and summer is correlated directly with seawater temperature of the winter-early spring ( between December and March ) and the other seasonal growth rate has no relationship with seasonal variations of seawater temperature. We propose that seawater temperature is one of the factors affecting the coral growth rate in the area and the low seawater temperature is a primary control of the seasonal growth rate.     

Stock Evaluation of Three Littoral Echinoid Species on the Catalan Coast North-Western Mediterranean

Abstract. We estimated the abundances of the three common littoral echinoid species Paracentrotus lividus, Arbacia lixula and Sphaerechinus granularis in a littoral zone between 0 and 10m depth on the Catalan shores NE Spain. Densities of each species were estimated from a total number of 11 571× 1 m² sampling units deployed at 152 sites along the 13 zones into which the coast was divided. The surface area available in each of these zones was estimated at the scale of the sampling unit 1 m² taking into account the fractal dimension of the shore. The stocks individuals > 2cm test diameter of these species for the whole Catalan shore ≅ 300 km, straight-line distance were estimated to be about 279.1 × 10⁶ individuals for P. lividus , 28.9 × 10⁶ individuals for A. lixula and 10.9 × 10⁶ individuals for S. granularis. These sea-urchins are key species in the regulation of algal communities and some of them P. lividus. S. granularis are of commercial interest. This information will provide a tool for the future monitoring and management of this resource, which now faces diverse pressures of human origin.     

南沙海区珊瑚礁灰岩纵波波速特征及其影响因素 *

珊瑚礁灰岩是孔隙结构复杂、密度变化较大的一类岩石, 但过去对珊瑚礁灰岩纵波波速与孔隙结构的关系及其影响因素研究不够深入。本文测定和分析了南沙海区某岛礁钻孔中珊瑚礁灰岩的纵波波速、孔隙度以及密度特征, 结果显示礁灰岩的纵波波速变化范围为5104~5958m·s^-1, 孔隙度变化范围为1.47%~17.7%, 密度变化范围为2.07~ 2.72g·cm^-3。这些特征表明, 埋藏后的压实作用和重结晶作用, 对珊瑚礁灰岩的孔隙度和密度产生影响。珊瑚礁灰岩弹性波速主要受孔隙度和孔隙结构类型的影响, 礁灰岩横、纵波速比值能有效地确定岩体的结构和稳定性, 因此礁灰岩的声学特性研究成果可为珊瑚岛礁工程建设的稳定性评估提供可靠的数据支撑。     

Coral bleaching and habitat effects on colonisation of reef fish assemblages: An experimental study

Degradation and mortality of corals is increasing worldwide and is expected to have significant effects on coral reef fish; hence studies on these effects are essential. In the present study, a field experiment was set up within Mafia Island Marine Park in Tanzania (East Africa) to examine the effects of bleaching and habitat structure on colonisation of coral reef fish assemblages. Live and bleached staghorn coral Acropora formosa was transplanted onto plots in a site dominated by sand and rubble, and the experimental design comprised of three treatments: live coral, bleached coral and eroded coral rubble. There was an immediate increase (within 24 h) in fish abundance and diversity in the two treatments with standing corals. Overall, live and bleached coral plots showed similar effects, but differed from the eroded coral plots which had a much lower abundance and diversity of fish. In general, fish species diversity changed with time over the study period while fish abundance did not. Multivariate analyses showed that while there were differences in fish assemblage structure between standing corals and the eroded coral treatment, there was neither a difference between live and bleached coral treatments nor any temporal effects on fish assemblage structure. Our findings suggest that physical structure and complexity of habitat have stronger effects on colonisation of reef fish assemblages than changes in coral health (such as bleaching) which do not affect coral structure. This may have important implications for appropriate coral reef management.     

近165年来中沙环礁中北暗沙滨珊瑚生长率及其对海温变化的响应

海水温度是控制珊瑚生长的关键环境因素之一, 随着全球气候变暖, 海温持续升高已成为珊瑚生长面临的全球性威胁。文章对采自中沙环礁中北暗沙水深约16m的澄黄滨珊瑚岩心样品开展了生长率分析, 揭示出中沙环礁滨珊瑚近165年来的生长历史及变化规律; 并通过与西沙群岛永兴岛滨珊瑚生长率的对比, 探讨了南海中部滨珊瑚生长的区域差异及其对海温升高的响应关系。过去100多年来中北暗沙和永兴岛海区的平均海温分别为(27.4±0.37)℃和(27.09±0.36)℃, 两个海区的海温均呈线性升高趋势, 升温速率一致, 约为0.43℃·ha^-1。过去100多年间中北暗沙和永兴岛滨珊瑚的平均生长率分别为(0.70±0.16)cm·a^-1和(1.19±0.16)cm·a^-1, 但中北暗沙滨珊瑚生长率呈线性下降趋势, 下降速率约为9.4%·ha^-1; 而永兴岛滨珊瑚生长率呈线性上升趋势, 增长速率约为10.9%·ha^-1。过去100多年间两个礁区的滨珊瑚生长率均存在年代际波动, 大致与海温的年代际波动对应。两个礁区滨珊瑚生长率与海温在趋势上呈现非线性响应关系, 存在滨珊瑚生长的最适宜温度约为27.25℃, 过去100多年来中北暗沙海域海温的增温趋势已经超出了滨珊瑚生长的适宜海温范围, 限制了滨珊瑚的生长趋势, 而永兴岛海域海温仍适宜滨珊瑚的生长。在年代际波动上两个礁区滨珊瑚生长率与海温存在线性正相关关系, 海温的年代际增温有利于滨珊瑚生长。在南海未来持续海水升温的情况下, 中北暗沙珊瑚生长的下降趋势将会进一步加剧, 并将严重威胁中沙珊瑚礁生态系统的维持和发展。     

A new coral reef province in the Gulf of Carpentaria, Australia: Colonisation, growth and submergence during the early Holocene

Multibeam sonar mapping, drill cores and underwater video data have confirmed the existence of a previously unknown coral reef province in the Gulf of Carpentaria, Australia. Seven reefs, comprised of coral limestone that support living corals have been mapped so far and as many as 50 other reefs may exist in the region. U/Th ages show that reef growth commenced shortly after limestone pedestals were submerged by rising sea level around 10.5 kyr BP, making them the oldest Holocene reefs known in Australia. Reef growth persisted for ~ 2.0 kyr but it had ceased at most locations by ~ 7.0 kyr BP. Measurements of reef growth rates (0.95 to 4 m kyr^− 1), indicate that the reefs were unable to keep pace with contemporaneous rapid sea level rise (> 10 m kyr^− 1), which is consistent with a “give up” reef growth history. Core samples from reef platforms demonstrate that Pleistocene limestone is exposed at depths of 27 and 30 m below present mean sea level. These depths represent regionally significant phases of reef growth during a prolonged sea level still stand. We conclude that the reefs are therefore mostly relict features, whose major phase of growth and development relates to an earlier, pre-Holocene sea level still stand.     

基于Ecopath模型的七连屿礁栖性生物的生态承载力分析

生态承载力评估是开展生物资源增殖放流, 维持珊瑚礁生态系统健康的基础和前提。本文基于2019年渔业资源和生态环境的综合调查数据, 构建了七连屿珊瑚礁海域生态系统的生态通道(Ecopath)模型, 分析和探讨了相关功能组增殖放流的生态承载力。结果显示, 七连屿珊瑚礁海域生态系统各功能群营养级范围为1.00~3.81; 生态系统的总能量转化效率为13.45%; 生态系统以牧食食物链占据主导地位, 直接来源于初级生产者的能流占比为57%。系统总初级生产量/总呼吸量为2.54; 总初级生产量/总生物量为19.07; 系统连接指数和系统杂食性指数分别为0.36和0.22, 表明当前七连屿珊瑚礁海域生态系统的成熟度和稳定性偏低, 系统对于外界的干扰抵抗能力较弱。在未改变七连屿珊瑚礁生态系统结构和功能的前提下, 各功能组中珊瑚、双壳类和植食性鱼类的生态承载力分别为25.09~53.77t•km^-2、2.55~39.95t•km^-2和4.89~17.94t•km^-2, 因此仍具有较大的增殖空间。珊瑚礁鱼类群落的最大生态承载力同珊瑚礁无脊椎动物群落的增殖密切相关, 在未来的珊瑚礁渔业管理中应从生态系统整体结构的角度综合考虑增殖放流的方法设计。     

Microbial Biomass Dynamics Along a Trophic Gradient at the Atlantic Barrier Reef off Belize (Central America)

Abstract. Recent findings indicate that heterotrophic bacteria and not phytoplankton are the most numerous biomass components even in the euphotic zone of oligotrophic, open oceans. In this study it was hypothesized that the microbial biomass components change within a few hundred meters as oligotrophic water flows across the reef and becomes enriched with nutrients. Along a trophic gradient, four stations at the Atlantic Barrier Reef off Belize (Central America) were sampled for microbial biomass components. Phytoplankton biomass (measured as chlorophyll a) ranged from the most oligotrophic station (St. 1) to the most eutrophic station (St. 4) from 6.9–415.5 μg CI"' (assuming a C:chl a ratio of 30): heterotrophic bacterial biomass increased 4-fold (from 10.1–46.4μg C 1^-1), heterotrophic nanoflagellate (HNAN) biomass increased from 4.6-19ug C 1^-1, and cyanobacteria from 0.9-4.5 μg C-1^-1. Production estimates derived from seawater cultures revealed a 5-fold increase in bacterial production from the oligotrophic station (3.7 ug C 1^-1 d^-1) to the eutrophic St. 4 (17.8ug C-1-d1^-1)- Cyanobacterial production rose from 1.1–3.5ug C-1–d^-1 and HNAN production from 0.65-1.13 μg C-1^-1 -d^-1. While cyanobacteria contributed between 13 and 20% to the autotrophic plankton component in the oligotrophic waters, their contribution dropped to about 1 % at the eutrophic stations.     

Seasonal and Spatial Variations of Total Mass Flux around Coral Reefs in the Southern Ryukyus,Japan

Total mass flux, size distribution of sediment particles and some chemical components such as total carbon (TC), total nitrogen (TN) and calcium carbonate (CaCO₃) were monitored monthly using a multi-cup sediment traps at seven coral reef sites (6 reef flat and 1 reef slope) of the Marine Protected Areas around Ishigaki, Kohama, Kuroshima and Iriomote Islands in the southern Ryukyus, Japan from September 2000 to September 2001. The size distribution of trapped sediments revealed mostly uni-modal fine sand to mud in the reef flat and gravelly to coarse sand in the reef slope. The total mass flux ranged between 0.54 to 872 gm⁻²d⁻¹, and showed a pronounced seasonality (high in summer-autumn and low in spring) at each site, which was consistent with the rainfall and typhoon regime. Exceptionally high values were observed on the reef slope (Iriomote) in February–March 2001 (1533 gm⁻²d⁻¹) owing to a large amount of bottom sediment re-suspension. On the reef flat (Todoroki South and North; Ishigaki), values obtained in July–August 2001 (872 gm⁻²d⁻¹) and August–September 2001 (800 gm^{− 2}d⁻¹) indicate the high terrestrial discharge from Todoroki River. Trapped sediment particles consist of CaCO₃ (1.2–27.1%) and a non-carbonate fraction (98.8–72.9%), which contains total carbon (4.9–26%), carbonate carbon (CO₂-C) (0.2–3.1%) and non-carbonate carbon (NC-C) (7.9–25.6%). Total nitrogen content was in the range 0.02–0.48%. TN is contained mainly in the carbonate fraction and NC-C may be contained in the non-carbonate fraction. The low TN/OC ratio of the trapped sediments suggests that they were mostly of terrestrial origin and that both fractions migrated. The high total mass flux derived from Todoroki River exceeded the threshold at which a lethal effect on coral community is caused. The results stress the importance of conducting seasonal studies of sedimentation over more than one year and at more than one location in south Japan coral reef ecosystems to gain an understanding of the processes controlling the total mass fluxes and their nutrients content, also to develop an awareness of how to prevent the damage of coral reef ecosystems and, if it does occur, to allow mitigation measures to be undertaken.     

不同形态磷源对球形棕囊藻生长及囊体形成的影响

球形棕囊藻(Phaeocystis globosa)是中国近海常见的有害藻华原因种,游离单细胞和球形囊体是其异型生活史的两种形态.本研究通过添加KH2PO4(PO43-)、卵磷脂(LEC)、三磷酸腺苷二钠(ATP)、葡萄糖-6-磷酸钠盐(G-6-P)、和核糖核酸(RNA)5种不同磷源进行室内培养,以阐明不同磷源对球形棕...     

西沙群岛永兴岛礁坡石珊瑚覆盖率的空间变化

连续影像样方调查方法较常用的截线样条法具有空间分辨率高的特点.采用该方法于2008年7月在西沙群岛永兴岛礁坡开展了5条垂直岸线断面和2条平行岸线断面的石珊瑚覆盖率调查.调查发现,永兴岛珊瑚覆盖率存在显著的空间差异,北、西北和东部断面珊瑚分布相对较多,覆盖率较高;西和西南部断面珊瑚分布稀少,覆盖率低.其中北、西北和东部断面沿礁坡方向珊瑚分布明显减少,礁坡中上部30-50m以上、水深5-6m以浅的区域,珊瑚覆盖率高;而礁坡中下部50m以下、水深约6m以深区域,珊瑚分布少,覆盖率低.此外,北和西北部断面还发现由棘冠海星Acanthaster planci和黑皮海绵Terpios hoshinota分别造成的珊瑚白化和珊瑚黑死现象,一定程度上降低了珊瑚覆盖率.永兴岛珊瑚覆盖率的下降以及空间变化格局的形成主要与30年以来日益增加的人类活动和珊瑚礁区过度开发有关.