71 resultados para depth-first
em Publishing Network for Geoscientific
Resumo:
Ocean Drilling Program Leg 169S retrieved a complete Holocene sequence from Saanich Inlet, British Columbia, Canada. Fish and diatom remains were extracted from sediments at Site 1034. Very small fish bones, teeth and scales were ubiquitous except in the lowermost glaciomarine clays; scales degraded with depth. In the identifiable fraction, Pacific herring were the most abundant with Pacific hake and cartilaginous fish yielding significant fractions. Fish remains appear just before 12 000 BP but greatest diversity does not occur until about 6500 BP. A smoothed abundance curve highlights two periods of maximal abundance at about 1500 and 6500 BP. Abundances in the last 1000 years are lower than the rest of the record. A correlation with abundances of seven phytoplankton taxa is significant; diatoms explain about a third of the variance. This study demonstrates the use of fish and diatoms from the same paleosedimentary matrix to examine millennia-scale correlations between primary and tertiary production.
Resumo:
The Red Sea is a very young ocean, and is one of the most interesting areas on Earth (ocean in statu nascendi). It is the only ocean where hydrothermal activity associated with ore formation occurs in a sterile environment (anoxic, hot, saline). In addition, its geographical position means that it is predestined to record the monsoonal history of the region in detailed sedimentary sequences. The major aim of the present project is to investigate the dynamics of hydrothermal systems in selected Deeps (Atlantis-II, Discovery, Kebrit, Al Wajh), Additional palaeoceanographic and microbiological questions should also be addressed. Specific aims are: 1. To study the hydrographic changes in individual Deeps (hydrothermal region Atlantis-II) and to investigate the causes of the temperature increase in the last few years (increased heat flow - higher temperature of the brine supply - higher brine flow rates?). 2.a. To document the influence of the hydrothermal systems on the sedimentary organic matter in the Deeps. In particular, the thermogenic production and migration of hydrocarbons in the sediments will be studied. The complex formation mechanisms (bacterial, thermogenic) of short-chain hydrocarbons (trace gases) will also be examined, 2.b. in addition, the polar and macromolecular fraction in samples from the various deeps will be studied in order to elucidate the formation, structure and source of the macromolecular oil fraction. 3. To clarify the palaeoceanographic conditions, sea-level changes and the climatic history (relationship of the circulation system and nutrient supply to the monsoon) of the southern Red Sea. 4. To separate microorganisms from the brines and to characterise them in terms of their metabolic physiology and ecology, and to describe their taxonomy.
Resumo:
Vorliegender Band enthält die für alle internationalen Polarstationen obligatorischen meteorologischen Beobachtungen der russischen Polarstation an der Lenamündung für den Zeitraum vom 1. September 1882 bis 31. August 1883 und vom 1. September 1883 bis zum 6. Juli 1884.
Resumo:
The first record of Antipathella subpinnata ( Ellis and Solander, 1786) for the Azores archipelago is presented based on bottom longline by-catch analysis and ROV seafloor surveys, extending the species western-most boundary of distribution in the NE Atlantic. The species was determined using classic taxonomy and molecular analysis targeting nuclear DNA. Although maximum spine height on Azorean colonies branchlets is slightly smaller than that reported from Mediterranean colonies (0.12 vs 0.16 mm), the analysis of partial 18S rDNA, complete ITS1, 5.8S, ITS2 and partial 28S rDNA suggests that the Azorean and Mediterranean specimens belong to the same species. Video surveys of an A. subpinnata garden detected near Pico Island are used to provide the first in situ description of the species habitat in the region and the first detailed description of a black coral garden in the NE Atlantic. With A. subpinnata being the only coral found between 150 and 196 m depths, this is the deepest black coral garden recorded in the NE Atlantic and the first one to be monospecific. The species exhibited a maximum density of 2.64 colonies/m**2 and occurred across a surface area estimated at 67,333 m**2, yielding a local population estimate of 50,500 colonies.