Coral communities and reefs from Guerrero,Southern Mexican Pacific     

Ramón A. López‐Pérez  Luis E. Calderón‐Aguilera  Héctor Reyes‐Bonilla  José D. Carriquiry  Pedro Medina‐Rosas  Amilcar L. Cupul‐Magaña  María D. Herrero‐Pérezrul  Héctor A. Hernández‐Ramírez  Miguel Á. Ahumada‐Sempoal  Betsabe M. Luna‐Salguero 《Marine Ecology》2012,33(4):407-416

Corals in the Eastern Pacific extend south from the Gulf of California to Ecuador and oceanic Chile, and west from Colombia to Clipperton Atoll. Nevertheless, large stretches of the Mexican Pacific remain fundamentally unstudied. Therefore, to assess the current conditions of coral communities, a coastal fringe ～300 km long (17°40′ N, 101°39′ W to 16°46′ N, 99°49′ W) was surveyed within the Southern Mexican Pacific, between 2005 and 2009. Fifteen stony coral species were identified at 13 coral communities and six Pocillopora‐dominated fringing reefs, with Pocillopora verrucosa and Pocillopora damicornis the primary contributing taxa. Reef development was identified in embayments or behind rocks or islands that offered shelter from northern and northwestern winds. Observations of Pocillopora effusus, Pocillopora inflata, Porites lobata, Pavona clavus, and Pavona varians expanded the species known geographic ranges by several degrees of latitude, suggesting reef building fauna comprised a mixture of widespread and relatively rare Eastern Pacific corals. Results indicated greater live coral cover in the Ixtapa‐Zihuatanejo area (15–73%) than in the Acapulco localities, which had high algal dominance; the reefs in the latter region exhibited high erosion. Regional differences are likely the result of long‐standing anthropogenic pressures around Acapulco since 1950, when it became an important tourist destination. This paper is the first detailed report of ecologically stressed corals and coral reefs from the state of Guerrero on the Mexican Southern Pacific coast.  相似文献   

Cladocora caespitosa bioconstructions in the Columbretes Islands Marine Reserve (Spain,NW Mediterranean): distribution,size structure and growth     

Diego‐Kurt Kersting  Cristina Linares 《Marine Ecology》2012,33(4):427-436

Today, living banks of the coral Cladocora caespitosa appear to be restricted to a few Mediterranean locations and are threatened by the escalating impacts affecting coastal areas. In this study the exceptional occurrence of the Mediterranean coral C. caespitosa in the Columbretes Islands Marine Reserve (NW Mediterranean, Spain) is characterised in terms of spatial distribution, cover area, colony size and growth rates. The coral colonies form beds and banks in rocky bottoms within a semi‐enclosed bay that offers both hydrodynamic protection and high water exchange. The spatial distribution of the C. caespitosa colonies, from 5 to 27 m depth, is highly aggregated, depending on sea‐floor morphology and showing up to 80% of substrate coverage. The annual corallite growth rates obtained through the alizarin red staining method and x‐ray image analysis are similar, and range between 2.55 ± 0.79 mm and 2.54 ± 0.81 mm, respectively. The exceptional nature of these bioconstructions is due to their cumulative cover area, which is comparable in size to the largest C. caespitosa bioconstructions described to date in Mljet National Park (Croatia, Adriatic Sea).  相似文献   

Coral Reef Bleaching at Agatti Island of Lakshadweep Atolls,India     

Ramar Vinoth  Mohan Gopi  Thipramalai Thankappanpillai  Ajith Kumar  Thirunavukarassu Thangaradjou  Thangavel Balasubramanian 《青岛海洋大学学报(英文版)》2012,(1):105-110

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Modeling patterns of coral bleaching at a remote Central Pacific atoll     

Gareth J. Williams  Ingrid S. Knapp  Simon K. Davy 《Marine pollution bulletin》2010,60(9):1467-1476

A mild bleaching event (9.2% prevalence) at Palmyra Atoll occurred in response to the 2009 ENSO, when mean water temperature reached 29.8-30.1 °C. Prevalence among both abundant and sparse taxa varied with no clear pattern in susceptibility relating to coral morphology. Seven taxon-specific models showed that turbidity exacerbated while prior exposure to higher background temperatures alleviated bleaching, with these predictors explaining an average 16.3% and 11.5% variation in prevalence patterns, respectively. Positive associations occurred between bleaching prevalence and both immediate temperature during the bleaching event (average 8.4% variation explained) and increased sand cover (average 3.7%). Despite these associations, mean unexplained variation in prevalence equalled 59%. Lower bleaching prevalence in areas experiencing higher background temperatures suggests acclimation to temperature stress among several coral genera, while WWII modifications may still be impacting the reefs via shoreline sediment re-distribution and increased turbidity, exacerbating coral bleaching susceptibility during periods of high temperature stress.  相似文献   

Instability of coral limestone cliffs due to extreme waves     

Tetsuya Kogure  Yukinori Matsukura 《地球表面变化过程与地形》2010,35(11):1357-1367

Many boulders are located around the coastal cliffs with height of below 5 m made of coral limestone at Kuro‐shima, Okinawa, Japan. The origin of the boulders appears to be coral limestone cliffs which show developed notches. We undertook stability analysis, involving the wave pressure due to tsunamis, of wave‐induced collapse of the cliffs. We find that extreme waves are capable of inducing cliff collapse, as observed in circumstances where gravity is insufficient. Copyright © 2010 John Wiley and Sons, Ltd.  相似文献   

造礁珊瑚碳、氮、硼同位素的海洋酸化指示意义     

韩韬  余克服  陶士臣 《热带地理》2016,36(1):48-54

大气CO2体积分数升高导致的海洋酸化不仅会降低海水pH,还会改变其碳酸盐平衡体系,使得海水中文石饱和度（Ω）降低,相应地会降低珊瑚钙化的速率。已有研究表明：珊瑚骨骼δ13C、δ11B和δ15N具有记录Suess Effect、生物生产力、海水pH值以及营养源的能力;主要表现为：δ11B记录的pH值、δ13C记录的海水无机碳库（DIC）δ13C和生物生产力,以及δ15N记录的陆源物质输送量相结合,可用来指示受季风影响的南海“大陆架碳泵”和近海污染与海洋酸化的联系。目前关于珊瑚对海洋酸化的记录研究仍相对较少,珊瑚碳-氮-硼同位素组合的应用将会加深对于海洋酸化与气候变率和全球碳、氮循环的关系的认识,可能成为揭示海水pH值变化规律性的重要手段。  相似文献   

南海北部晚全新世高海平面及其波动的海滩沉积证据          下载免费PDF全文

余克服  陈特固 《地学前缘》2009,16(6):138

揭示晚全新世以来的海平面变化过程对于理解海平面所处的现状和变化的趋势等具有重要意义。构造活动相对稳定的雷州半岛珊瑚礁区蕴藏着丰富的海平面变化信息,文中对该区晚全新世发育的海滩沉积序列研究表明,距今约1.7～1.2Cal.kaBP(14C年代为2.1～1.7kaBP)期间总体上是一个海平面持续上升的时期,其中在距今约1.5Cal.kaBP时海平面有过短暂的下降波动,约1.2Cal.kaBP时的海平面比现在的至少高128cm;之后海平面开始下降,至今海岸线后退了约210m,形成现代海滩-沙堤地貌体系。结合本区珊瑚礁记录的全新世其他时段海平面的变化特征,本文认为全新世海平面与气候变化一样,也存在千年、百年、年代际尺度的波动特征。  相似文献   

The Enya mounds: a lost mound-drift competition     

D. Van Rooij  V. A. I. Huvenne  D. Blamart  J.-P. Henriet  A. Wheeler  H. de Haas 《International Journal of Earth Sciences》2009,98(4):849-863

The genesis and evolution of cold-water coral banks along the Northeastern Atlantic margin is known to be influenced by several factors, among which the palaeotopography and nature of the coral settling surface, the presence of bottom currents and sediment supply. In this paper, a case study is presented of the Enya mound cluster, located in the southernmost tip of the Belgica mound province, west of Ireland. Below this mound cluster, seismic stratigraphy revealed a yet unmapped local unconformity RD1b, being part of a composite erosion event (RD1). As such, from the Late Miocene to Late Pliocene, at least two erosional events have incised the margin, ending with the final RD1a “moundbase” unconformity, acting as a base for the Enya mounds. During the Quaternary the mounds became outgrown and were covered by a mounded contourite drift. In addition, they are closely associated with a cluster of seabed pockmarks. The bottom current regime which became active since the Middle Pleistocene has certainly influenced the fate of this mound cluster. The occurrence of the pockmarks seems to be related to relatively recent fluid migration processes, however leaving an open question if any previous seepage phases were involved in the growth or initiation of the coral banks.  相似文献   

Resistance of Lophelia pertusa to coverage by sediment and petroleum drill cuttings     

Elke Allers  Raeid M.M. Abed  Laura M. Wehrmann  Tao Wang  Ann I. Larsson  Autun Purser  Dirk de Beer 《Marine pollution bulletin》2013

In laboratory experiments, the cold-water coral Lophelia pertusa was exposed to settling particles. The effects of reef sediment, petroleum drill cuttings and a mix of both, on the development of anoxia at the coral surface were studied using O₂, pH and H₂S microsensors and by assessing coral polyp mortality. Due to the branching morphology of L. pertusa and the release of coral mucus, accumulation rates of settling material on coral branches were low. Microsensors detected H₂S production in only a few samples, and sulfate reduction rates of natural reef sediment slurries were low (<0.3 nmol S cm⁻³ d⁻¹). While the exposure to sediment clearly reduced the coral’s accessibility to oxygen, L. pertusa tolerated both partial low-oxygen and anoxic conditions without any visible detrimental short-term effect, such as tissue damage or death. However, complete burial of coral branches for >24 h in reef sediment resulted in suffocation.  相似文献   

A global inventory of coral reef stressors based on satellite observed nighttime lights   总被引：1，自引：0，他引：1  

C. Aubrecht  C. D. Elvidge  T. Longcore  C. Rich  J. Safran  A. E. Strong 《国际地球制图》2013,28(6):467-479

In this article, we present a satellite-based approach to gather information about the threat to coral reefs worldwide. Three chosen reef stressors – development, gas flaring and heavily lit fishing boat activity – are analysed using nighttime lights data derived from the Defense Meteorological Satellite Program (DMSP) produced at the National Oceanic & Atmospheric Administration, National Geophysical Data Center (NOAA/NGDC). Nighttime lights represent a direct threat to coral reef ecosystems and are an excellent proxy measure for associated human-caused stressors. A lights proximity index (LPI) is calculated, measuring the distance of coral reef sites to each of the stressors and incorporating the stressor's intensity. Colourized maps visualize the results on a global scale. Area rankings clarify the effects of artificial night lighting on coral reefs on a regional scale. The results should be very useful for reef managers and for state administrations to implement coral reef conservation projects and for the scientific world to conduct further research.  相似文献