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121.
Morphology and environment of cold-water coral carbonate mounds on the NW European margin 总被引:6,自引:0,他引:6
A. J. Wheeler A. Beyer A. Freiwald H. de Haas V. A. I. Huvenne M. Kozachenko K. Olu-Le Roy J. Opderbecke 《International Journal of Earth Sciences》2007,96(1):37-56
Cold-water coral carbonate mounds, owing their presence mainly to the framework building coral Lophelia pertusa and the activity of associated organisms, are common along the European margin with their spatial distribution allowing them
to be divided into a number of mound provinces. Variation in mound attributes are explored via a series of case studies on
mound provinces that have been the most intensely investigated: Belgica, Hovland, Pelagia, Logachev and Norwegian Mounds.
Morphological variation between mound provinces is discussed under the premise that mound morphology is an expression of the
environmental conditions under which mounds are initiated and grow. Cold-water coral carbonate mounds can be divided into
those exhibiting “inherited” morphologies (where mound morphology reflects the morphology of the colonised features) and “developed”
morphology (where the mounds assume their own gross morphology mainly reflecting dominant hydrodynamic controls). Finer-scale,
surface morphological features mainly reflecting biological growth forms are also discussed. 相似文献
122.
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
123.
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
124.
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
125.
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
126.
本文通过对晚石炭世及早二叠世几种常见复体四射珊瑚的骨骼,尤其是隔壁的电镜研究、划分出了4种重要的隔壁微细构造类型,并指出了这些微细构造类型的地层分布规律及其在分类中的意义。 相似文献
127.
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
128.
The Depth Limits of Red Sea Stony Corals: An Ecophysiological Problem (A Deep Diving Survey by Submersible) 总被引:2,自引:0,他引:2
Abstract. Along the Sinai coast of the Red Sea a deep diving survey with the research submersible GEO investigated the depth distribution of stony corals. 47 hermatypic species were identified below 50 m; 9 species extended below 100 m. Their depth distributions are related to light penetration. Observed changes in hermatype growth forms with depth were investigated and interpreted as photo-adaptations. 10 species of ahermatypic corals were found between 100–205 m. Ahermatype growth forms are adaptations to plankton feeding and do not change with depth. 相似文献
129.
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
130.
Little is known about species distribution patterns in deep-sea environments, primarily because sampling surveys in the high seas are expensive and time consuming. The increasing need to manage and protect vulnerable marine ecosystems, such as cold-water corals, has motivated the use of predictive modelling tools, which produce continuous maps of potential species or habitat distribution from limited point observations and full coverage environmental data. Rapid advances in acoustic remote sensing, oceanographic modelling and sampling technology now provide high quality datasets, facilitating model development with high spatial detail. This paper provides a short overview of existing methodologies for predicting deep-sea benthic species distribution, and illustrates emerging issues related to spatial and thematic data resolution, and the use of transect-derived species distribution data. In order to enhance the ecological relevance and reliability of deep-sea species distribution models, novel techniques are presented based on a case study predicting the distribution of the cold-water coral Lophelia pertusa in three carbonate mound provinces in Irish waters. Specifically, the study evaluates (1) the capacity of newly developed high-resolution (250 m grid cell size) hydrodynamic variables to explain local scale cold-water coral distribution patterns, (2) the potential value of species occurrence proportion data to maintain semi-quantitative information of coral prevalence (i.e. coverage) and sampling effort per grid cell within the response variable, and (3) mixed effect modelling to deal with spatially grouped transect data. The study shows that predictive models using vertical and horizontal flow parameters perform significantly better than models based on terrain parameters only. Semi-quantitative proportion data may decrease model uncertainty and increase model reliability, and provide a fruitful avenue of research for analysing large quantities of video data in a detailed yet time-efficient manner. The study concludes with an outlook of how species distribution models could improve our understanding of vulnerable marine ecosystem functioning and processes in the deep sea. 相似文献