93 resultados para Acetabulastoma arcticum


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The HCMR_SES_UNLUATA_CRUISES_TURKISH_STRAITS_CHLA & PP dataset was obtained on samples taken from 5 stations in the Dardanelles Straits, Marmara Sea and Bosporus Straits. These experiments were set up according to DoW of SESAME project. Microplankton species composition analysis was performed according to the Utermöhl's (1958) inverted microscope method. Samples for the identification and enumeration of larger phytoplankton cells (>5?m), were preserved in alkaline Lugol's solution.

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Question: How do interactions between the physical environment and biotic properties of vegetation influence the formation of small patterned-ground features along the Arctic bioclimate gradient? Location: At 68° to 78°N: six locations along the Dalton Highway in arctic Alaska and three in Canada (Banks Island, Prince Patrick Island and Ellef Ringnes Island). Methods: We analysed floristic and structural vegetation, biomass and abiotic data (soil chemical and physical parameters, the n-factor [a soil thermal index] and spectral information [NDVI, LAI]) on 147 microhabitat releves of zonalpatterned-ground features. Using mapping, table analysis (JUICE) and ordination techniques (NMDS). Results: Table analysis using JUICE and the phi-coefficient to identify diagnostic species revealed clear groups of diagnostic plant taxa in four of the five zonal vegetation complexes. Plant communities and zonal complexes were generally well separated in the NMDS ordination. The Alaska and Canada communities were spatially separated in the ordination because of different glacial histories and location in separate floristic provinces, but there was no single controlling environmental gradient. Vegetation structure, particularly that of bryophytes and total biomass, strongly affected thermal properties of the soils. Patterned-ground complexes with the largest thermal differential between the patterned-ground features and the surrounding vegetation exhibited the clearest patterned-ground morphologies.

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Presented are physical and biological data for the region extending from the Barents Sea to the Kara Sea during 158 scientific cruises for the period 1913-1999. Maps with the temporal distribution of physical and biological variables of the Barents and Kara Seas are presented, with proposed quality control criteria for phytoplankton and zooplankton data. Changes in the plankton community structure between the 1930s, 1950s, and 1990s are discussed. Multiple tables of Arctic Seas phytoplankton and zooplankton species are presented, containing ecological and geographic characteristics for each species, and images of live cells for the dominant phytoplankton species.

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Marine diatoms are the primary biostratigraphical and paleoenvironmental tool for interpreting the upper Palaeogene and lower Neogene strata recovered during the second drilling season of the Cape Roberts Project at site CRP-2 in the western Ross Sea, Antarctica. Silicoflagellates, ebridians, and a chrysophyte cyst provide supporting biostratigraphical information. More than 100 dominantly planktic diatom taxa are recognised. Of these, more than 30 are treated informally, pending SEM examination and formal description. Many other taxa are noted only to generic level. Lower Oligocene (c. 31 Ma) through lower Miocene (c. 18.5 Ma) diatoms occur from 28 mbsf down to 565 mbsf. Below this level, to the bottom of the hole at 624.15 mbsf, diatom assemblages are poorly-preserved and many samples are barren. A biostratigraphic zonal framework, consisting of ten diatom zones, is proposed for the Antarctic continental shelf. Ages inferred from the diatom biostratigraphy correspond well with geochronological data from argon dating of volcanic materials and strontium dating of calcareous macrofossils, as well as nannofossil biochronological datums. The biochronostratigraphical record from CRP-2/2A provides an important record of diatom events and mid-Cenozoic environmental changes in the Antarctic neritic zone.

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Fundamental analytical pyrolysis studies of biomass from Polar seaweeds, which exhibit a different biomass composition than terrestrial and micro-algae biomass were performed via thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass-spectrometry (Py-GC/MS). The main reason for this study is the adaptation of these species to very harsh environments making them an interesting source for thermo-chemical processing for bioenergy generation and production of biochemicals via intermediate pyrolysis. Several macroalgal species from the Arctic region Kongsfjorden, Spitsbergen/Norway (Prasiola crispa, Monostroma arcticum, Polysiphonia arctica, Devaleraea ramentacea, Odonthalia dentata, Phycodrys rubens, Sphacelaria plumosa) and from the Antarctic peninsula, Potter Cove King George Island (Gigartina skottsbergii, Plocamium cartilagineum, Myriogramme manginii, Hymencladiopsis crustigena, Kallymenia antarctica) were investigated under intermediate pyrolysis conditions. TGA of the Polar seaweeds revealed three stages of degradation representing dehydration, devolatilization and decomposition of carbonaceous solids. The maximum degradation temperatures Prasiola crispa were observed within the range of 220-320 C and are lower than typically obtained by terrestrial biomass, due to divergent polysaccharide compositions. Biochar residues accounted for 33-46% and ash contents of 27-45% were obtained. Identification of volatile products by Py-GC/MS revealed a complexity of generated chemical compounds and significant differences between the species. A widespread occurrence of aromatics (toluene, styrene, phenol and 4-methylphenol), acids (acetic acid, benzoic acid alkyl ester derivatives, 2-propenoic acid esters and octadecanoic acid octyl esters) in pyrolysates was detected. Ubiquitous furan-derived products included furfural and 5-methyl-2-furaldehyde. As a pyran-derived compound maltol was obtained by one red algal species (P. rubens) and the monosaccharide d-allose was detected in pyrolysates in one green algal (P. crispa). Further unique chemicals detected were dianhydromannitol from brown algae and isosorbide from green algae biomass. In contrast, the anhydrosugar levoglucosan and the triterpene squalene was detected in a large number of pyrolysates analysed. © 2013 Elsevier B.V. All rights reserved.