255 resultados para Pelagic Occurrences


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The metabolic rate of organisms may either be viewed as a basic property from which other vital rates and many ecological patterns emerge and that follows a universal allometric mass scaling law; or it may be considered a property of the organism that emerges as a result of the organism's adaptation to the environment, with consequently less universal mass scaling properties. Data on body mass, maximum ingestion and clearance rates, respiration rates and maximum growth rates of animals living in the ocean epipelagic were compiled from the literature, mainly from original papers but also from previous compilations by other authors. Data were read from tables or digitized from graphs. Only measurements made on individuals of know size, or groups of individuals of similar and known size were included. We show that clearance and respiration rates have life-form-dependent allometries that have similar scaling but different elevations, such that the mass-specific rates converge on a rather narrow size-independent range. In contrast, ingestion and growth rates follow a near-universal taxa-independent ~3/4 mass scaling power law. We argue that the declining mass-specific clearance rates with size within taxa is related to the inherent decrease in feeding efficiency of any particular feeding mode. The transitions between feeding mode and simultaneous transitions in clearance and respiration rates may then represent adaptations to the food environment and be the result of the optimization of tradeoffs that allow sufficient feeding and growth rates to balance mortality.

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The metabolic rate of organisms may either be viewed as a basic property from which other vital rates and many ecological patterns emerge and that follows a universal allometric mass scaling law; or it may be considered a property of the organism that emerges as a result of the organism's adaptation to the environment, with consequently less universal mass scaling properties. Data on body mass, maximum ingestion and clearance rates, respiration rates and maximum growth rates of animals living in the ocean epipelagic were compiled from the literature, mainly from original papers but also from previous compilations by other authors. Data were read from tables or digitized from graphs. Only measurements made on individuals of know size, or groups of individuals of similar and known size were included. We show that clearance and respiration rates have life-form-dependent allometries that have similar scaling but different elevations, such that the mass-specific rates converge on a rather narrow size-independent range. In contrast, ingestion and growth rates follow a near-universal taxa-independent ~3/4 mass scaling power law. We argue that the declining mass-specific clearance rates with size within taxa is related to the inherent decrease in feeding efficiency of any particular feeding mode. The transitions between feeding mode and simultaneous transitions in clearance and respiration rates may then represent adaptations to the food environment and be the result of the optimization of tradeoffs that allow sufficient feeding and growth rates to balance mortality.

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Fish stomach content records extracted from the DAPSTOM 4.5 database (held at the UK Centre for Environment, Fisheries and Aquaculture Science - CEFAS). Data collated as part of the EU Euro-Basin project and specifically concerning herring (Clupea harengus), mackerel (Scomber scombrus), blue whiting (Micromesistius poutassou), albacore (Thunnus alalunga) and bluefin tuna (Thunnus thynnus). The data set consist of 20720 records - collected throughout the northeast Atlantic, between 1906 and 2011 - mostly during routine fisheries monitoring research cruises.

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For determining importance, composition, and history of aerosol material accumulation in formation of pelagic clays a study with use of light microscopy and scanning electron microscopy, X-ray diffractometry, and chemical methods has been carried out.

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Results of petrographic, chemical and X-ray studies of zeolites in sediments in the Transpacific lithological profile from the coast of Japan to the coast of Mexico are reported. For ocean phillipsites constancy of Si/Al ratio (2.44-2.87) and unstable cation composition in quantitative predominance of potassium over sodium are characteristic. Two groups of ocean phillipsites are distinguished: of deep-water basins and of submarine rises. The first spread over broad areas of the pelagic zone, and are formed by diagenetic transformation of fine dispersed pyroclastic material in minimum sedimentation rates, the latter occur locally - in areas of basaltic volcanism manifestations.

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Diatom assemblages from 228 core-top samples were investigated to determine the modern geographic distributions of 10 major open ocean species or species groups in the Atlantic and Indian sectors of the Southern Ocean. Our study gives a more comprehensive view of the relationships between diatom distribution and environmental pressures than previous studies, as our modern database covers a much wider area, and additionally highlights the relationships with sea ice cover and concentration. The 10 species or species categories can mainly be lumped into three groupings. First, a cool open ocean grouping composed of Rhizosolenia pointed group, Thalassiosira gracilis group and Trichotoxon reinboldii with maximum relative abundances occurring within the maximum winter sea-ice edge. Second, a pelagic open ocean grouping composed of Fragilariopsis kerguelensis, Thalassiosira lentiginosa, Thalassiosira oliverana and Thalassiothrix spp. group with maximum occurrences at the Antarctic Polar Front. Third, a warm open ocean grouping with maximum abundances observed within the Polar Front Zone and composed of the Rhizosolenia rounded group, the Thalassionema nitzschioides var. nitzschioides group and the Thalassionema nitzschioides var. lanceolata. Comparisons of the abovementioned 10 species or species groups with modern February sea-surface temperatures and sea-ice duration and concentration reveal species-specific sedimentary distributions regulated both by sea-surface temperatures and sea ice conditions that support the use of diatom remains to reconstruct past variations of these environmental parameters via qualitative and transfer function approaches.

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As a limiting nutrient to marine life, phosphorus (P) is an effective tracer of today's marine productivity. The distribution of P in marine sediments likewise tracks the history of marine productivity because of its relative insolubility in seawater. CaCO3, biogenic opal, terrigenous sediment, and total P have been measured in cores from nine Pacific sites (Deep Sea Drilling Project (DSDP) 65, 66, 310, 77, 62, 572, 463, 586, and GPC-3) and one subantarctic (DSDP 266) site. These sites were specifically chosen to provide information on biota burial flux changes with time for sedimentary sinks that represent key oceanographic variables, i.e., rate of upwelling, water depth, and carbonate dissolution gradient. The accumulation rates of these components for the last 10 Ma were then calculated from determined core age versus depth plots, core bulk density, and porosity data. The accumulation of P weakly correlates with that of CaCO3, moderately with that of total sediment, and very strongly with carbonate-free accumulation. Two prominent peaks for all components occur at 2-3 Ma and 5-6 Ma, and record the chemical loading of dissolved CaCO3, SiO2, and P from glacially emergent continental shelves. These results indicate that continental shelf phosphorites form during interglacially high sea levels and correspond to low deep-sea P accumulation rates, whereas glacially lowered sea levels allow for shelf bypassing and greater deep-sea P accumulation rates.

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The object of the detailed investigations was an unusual material collected in the region of the Southern Basin of the Pacific Ocean floor, with features of intense manifestation of volcanic processes and subsequent hydrothermal alterations. These processes to a significant degree transformed the ferromanganese nodules and the pelagic sediments, causing the development of a new type of oceanic manganese mineralization.

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Data on age, total length, total weight, gonad weight, gonadosomatic index (GSI), sex and reproductive stage for ice fish specimens collected along the sea ice gradient in McMurdo Sound, Antarctica. Species on which data are provided are; Trematomus bernacchii, Trematomus bernacchii, Pagothenia borchgrevinki and Trematomus newnesi. Location and year of collection is also included for each fish.