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101.
Simone Siag Oigman-Pszczol Marcia A. de O. Figueiredo & Joel C. Creed 《Marine Ecology》2004,25(3):173-190
Abstract. Few studies have described the spatial patterns of rocky sublittoral benthic communities in Brazil, where these habitats are almost exclusively located on the southeast and south coastline. The fauna and flora were analyzed using a quadrat method, and the species abundance and distribution were determined along transects down to the bottom sand plain on 10 rocky shores at Armação dos Búzios, Brazil. The 16 most common species accounted for around 97% of the benthos coverage and included cnidarians, algae, poriferans, and echinoderms. Cnidarians and algae were the most important groups, with abundance ranging from 13–66% and 27–68%, respectively. The species distribution indicated a clear depth zonation pattern. The algal community dominated the shallowest depths in sites more exposed to waves and steeper substrate slope, whereas the cnidarian community, divided into the zoanthidean Palythoa caribaeorum and the coral Siderastrea stellata , was more abundant from intermediate to greater (4 m) depths. Different community patterns were found between sites, demonstrating that different spatially discrete factors may be acting on each rocky shore. 相似文献
102.
Benthic dynamics at the carbonate mound regions of the Porcupine Sea Bight continental margin 总被引:4,自引:2,他引:4
Martin White 《International Journal of Earth Sciences》2007,96(1):1-9
A brief review is given of some dynamical processes that influence the benthic dynamics within the carbonate mound provinces
located at the Porcupine Bank/Sea Bight margin, NE Atlantic. The depth range of the mounds in this region (600–1,000 m) marks
the upper boundary of the Mediterranean outflow water above which Eastern North Atlantic Water dominates. Both water masses
are carried northwards by the eastern boundary slope current. In the benthic boundary layer both the action of internal waves,
and other tidal period baroclinic waves, may enhance the bottom currents and add to both the residual and maximum flow strength.
Both residual and maximum bottom currents vary at different mound locations, with stronger currents found at Belgica (SE Porcupine
Sea Bight) mound and Pelagia (NW Porcupine Bank) mound regions, whilst weakest currents are found at the Hovland and Magellan
Mounds at the northern Sea Bight margin. The differences may be attributed to the presence of internal waves (Pelagia) or
bottom intensified diurnal waves (Belgica). These different dynamical regimes are likely to have implications for the distribution
patterns of live coral at the different locations. 相似文献
103.
Environmental changes and growth history of a cold-water carbonate mound (Propeller Mound,Porcupine Seabight) 总被引:4,自引:0,他引:4
Andres Rüggeberg Christian Dullo Boris Dorschel Dierk Hebbeln 《International Journal of Earth Sciences》2007,96(1):57-72
On- and off-mound sediment cores from Propeller Mound (Hovland Mound province, Porcupine Seabight) were analysed to understand
better the evolution of a carbonate mound. The evaluation of benthic foraminiferal assemblages from the off-mound position
helps to determine the changes of the environmental controls on Propeller Mound in glacial and interglacial times. Two different
assemblages describe the Holocene and Marine Isotope Stage (MIS) 2 and late MIS 3 (∼31 kyr BP). The different assemblages
are related to changes in oceanographic conditions, surface productivity and the waxing and waning of the British Irish Ice
Sheet (BIIS) during the last glacial stages. The interglacial assemblage is related to a higher supply of organic material
and stronger current intensities in water depth of recent coral growth. During the last glaciation the benthic faunas showed
high abundances of cassidulinid species, implying cold bottom waters and a reduced availability of organic matter. High sedimentation
rates and the domination of Elphidium excavatum point to shelf erosion related to sea-level lowering (∼50 m) and the progradation of the BIIS onto the shelf. A different
assemblage described for the on-mound core is dominated by Discanomalina coronata, Gavelinopsis translucens, Planulina ariminensis, Cibicides lobatulus and to a lower degree by Hyrrokkin sarcophaga. These species are only found or show significantly higher relative abundances in on-mound samples and their maximum contribution
in the lower part of the record indicates a higher coral growth density on Propeller Mound in an earlier period. They are
less abundant during the Holocene, however. This dataset portrays the boundary conditions of the habitable range for the cold-water
coral Lophelia pertusa, which dominates the deep-water reefal ecosystem on the upper flanks of Propeller Mound. The growth of this ecosystem occurs
during interglacial and interstadial periods, whereas a retreat of corals is documented in the absence of glacial sediments
on-mound. Glacial conditions with cold intermediate waters, a weak current regime and high sedimentation rates provide an
unfavourable environmental setting for Lophelia corals to grow. A Late Pleistocene decrease is observed in the mound growth for Propeller Mound, which might face its complete
burial in the future, as it already happened to the buried mounds of the Magellan Mound province further north. 相似文献
104.
Yu. D. Zakharov S. P. Pletnev M. E. Mel’nikov O. P. Smyshlyaeva V. D. Khudik G. A. Evseev T. A. Punina P. P. Safronov A. M. Popov 《Russian Journal of Pacific Geology》2007,1(1):29-41
The occurrence of belemnites in Mesozoic sediments of the Pacific guyots is established for the first time (rostra Dimitobelidae gen. et sp. indet. from the late Campanian-Maastrichtian detrital limestone of the DVGI Guyot, Belemnitella? sp. from oolitic limestone of the Gelendzhik Guyot, which are presumably of the Santonian-Maastrichtian age, and Belemnitidae? gen. et sp. indet. from the Maastrichtian oolitic limestone of the Butakov Guyot, the Magellan Rise). In recent years, fossil cephalopods important in stratigraphic and paleobiogeographic aspects have been found at five guyots of that rise. New data on fossil invertebrates from the study region suggest breaks in the sedimentation here at the terminal Maastrichtian, Paleogene, and initial Neogene time. Possible limits of vertical migration in the tropical Pacific are estimated for the Late Cretaceous belemnites based on preliminary results of the oxygen isotope analysis. 相似文献
105.
Corals are animals living in shallow seas (where they may form coral reefs) or in the deep sea. Because they fossilize well, these stones inform us in detail about the geological past; not only about the history of the Earth as a whole (rotation, tectonics, sea-level changes), but also about past local environmental conditions in the sea. Joint research of marine biology and marine geology can therefore solve many questions about our changing world, and can be used to discover what factors cause deterioration of living coral reefs. 相似文献
106.
广西恭城地区的额头村组珊瑚化石极为丰富,自上往下共有20余层之多,共建立了Cystophrentis、Caninia dorlodoti及Ceriphyllum elegantum 3个珊瑚组合带,如此连续及完整的珊瑚组合带在广西同类地层中尚属首次发现. 相似文献
107.
通过nlsrDNA(nuclear large-subunit ribosomal DNA)及nssrDNA(nuclear small-subunit ribosomal DNA)的PCR-RFLP研究广东徐闻地区8科15属25种62个造礁石珊瑚样本的共生藻。结果表明,共生藻nlsrDNA的RsaI酶切基因型只存在一种,属于C系群共生藻;而nssrDNA的MobⅠ和TaqⅠ两种酶切都存在两种基因型。实验进一步通过PCR直接测序法得到62个造礁石珊瑚样品的共生藻ITS序列,与GenBank上的4种虫黄藻ITS序列构建Neighbor-Joining系统发育树,结果表明该区的造礁石珊瑚共生两种不同种类(亚系群)的共生藻,分别为C1亚系群与C15亚系群共生藻,两个亚系群间的遗传距离为0.019。广东徐闻地区造礁石珊瑚共生藻多样性偏低,暗示该地区珊瑚礁生态系统应对环境变化的能力可能较弱。 相似文献
108.
Ben De Mol Max Kozachenko Andy Wheeler Hugo Alvares Jean-Pierre Henriet Karine Olu-Le Roy 《International Journal of Earth Sciences》2007,96(1):103-120
High-resolution seismic profiles, swath bathymetry, side-scan sonar data and video imageries are analysed in this detailed
study of five carbonate mounds from the Belgica mound province with special emphasis on the well-surveyed Thérèse Mound. The
selected mounds are located in the deepest part of the Belgica mound province at water depths of 950 m. Seismic data illustrate
that the underlying geology is characterised by drift sedimentation in a general northerly flowing current regime. Sigmoidal
sediment bodies create local slope breaks on the most recent local erosional surface, which act as the mound base. No preferential
mound substratum is observed, neither is there any indication for deep geological controls on coral bank development. Seismic
evidence suggests that the start-up of the coral bank development was shortly after a major erosional event of Late Pliocene–Quaternary
age. The coral bank geometry has been clearly affected by the local topography of this erosional base and the prevailing current
regime. The summits of the coral banks are relatively flat and the flanks are steepest on their upper slopes. Deposition of
the encased drift sequence has been influenced by the coral bank topography. Sediment waves are formed besides the coral banks
and are the most pronounced bedforms. These seabed structures are probably induced by bottom current up to 1 m/s. Large sediment
waves are colonised by living corals and might represent the initial phase of coral bank development. The biological facies
distribution of the coral banks illustrate a living coral cap on the summit and upper slope and a decline of living coral
populations toward the lower flanks. The data suggest that the development of the coral banks in this area is clearly an interaction
between biological growth processes and drift deposition both influenced by the local topography and current regime. 相似文献
109.
对扬子区中奥陶世至晚志留世四射珊瑚已发表的属种进行全面清理和厘定。现统计扬子区中奥陶世至晚志留世四射珊瑚约有117个属,其中以晚奥陶世和早志留世珊瑚属数最多。117个属中至少有30个属最早出现在扬子区中、晚奥陶世和早志留世地层。因此,扬子区被认为是奥陶纪、志留纪四射珊瑚起源中心之一。完善和修订扬子区中奥陶世至晚志留世四射珊瑚组合序列,使地层时代划分上均与国际通行标准(统、阶)接轨。尤其对扬子区早志留世Rhuddanian晚期,Aeronian早、晚期以及Telychian早、晚期四射珊瑚组合的重新建立和细分。最新资料表明晚奥陶世观音桥四射珊瑚动物群不但有更多的北欧同期的珊瑚分子,而且还产有北美标准属种Salvadorea,Brachyelasmasubregulare等说明两者也存在一定的联系。扬子区早志留世(Llandovery)的众多四射珊瑚属均为世界广布的,但也有许多地方性属(约有22个,占总数的23·4%)。就珊瑚生物古地理关系,它与同期的西伯利亚、哈萨克斯坦和澳大利亚珊瑚群较密切。 相似文献
110.
《Comptes Rendus Geoscience》2018,350(5):212-221
Sedimentological and geochemical studies of boxcores from the Brittlestar Ridge I and Cabliers carbonate mounds, along the Moroccan Mediterranean margin, show that sediments are composed of cold water scleratian corals and micritic mud, muddy micrite or muddy allochem limestone matrix, outlining seven different facies that can be attributed to “cluster reefs”. The mixed siliciclastic/carbonate sediments have been derived from both extra- and intrabasinal sources. Extra-basinal sources may be the geological formations outcropping in the Moroccan hinterland and Sahara, the latter including corals and associated bioclasts. Sediments were transported by wind and rivers and redistributed by bottom currents and local upwelling. Our results confirm the role of tectonics in the genesis of these carbonate mounds and reveal that their developments during the Holocene (10.34–0.91 ka BP) was controlled by climatic fluctuations (e.g. Holocene Climate Optimum and Little Ice Age), eustatic sea level change, and hydrodynamic regime. 相似文献