17 resultados para Peru. Marina
em Doria (National Library of Finland DSpace Services) - National Library of Finland, Finland
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Doctoral dissertation, University of Turku
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Roma : A. Lafreri 1572
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Kirja-arvio
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This thesis includes detailed sedimentological and ichnological studies on two geological units: the Pebas Formation, with a special focus in its informal upper member, and the Nauta Formation. Both formations were deposited during the Miocene in Northeastern Peruvian Amazonia, in the Amazon retroarc foreland basin. The Pebas and Nauta successions mainly consist of non-consolidated, clastic sedimentary deposits arranged into sand- to mud-dominated heterolithic successions, which can be upward-coarsening to upward-fining. Sediments in both the Pebas and Nauta successions range from mud to fine- to medium-grained sand. The main facies observed were 1) mud-dominated horizontal heterolithic couplets; 2) rooted brownish mud; 3) lenticular, mud-draped, cross-stratified sand; 4) mud- to sand-dominated, inclined heterolithic stratification; 5) sand-dominated horizontal heterolithic couplets; and 6) mud-draped, trough cross-stratified sand. Locally, tidal rhythmites were documented. The facies are interpreted as: 1) muddy, shallow, subaqueous flats/shoals; 2) palaeosols; 3) secondary tidal channels or run-off creeks; 4) tidally influenced point bars; 5) shoreface deposits; and 6) subtidal compound dunes. Thalassinoides-dominated Glossifungites ichnofacies, low-diversity expressions of the Skolithos ichnofacies and depauperate suites consisting of elements common to the Cruziana ichnofacies strongly indicate brackish-water conditions. However, continental trace fossil assemblages, with possible elements common to the Scoyenia ichnofacies, have also been identified. In addition to the palaeoenvironmental study, a local hydrogeochemical characterisation of the Pebas and Nauta formations was also conducted. The geochemistry of the groundwaters reflects the characteristics and the soil geochemistry of the geological formations studied. The Pebas formation has low hardness, acid to neutral waters, whereas the upper Pebas has high hardness, acid to neutral waters. In both units, the arsenic content is locally high. The Nauta formation has low hardness acid groundwaters. A regional review of the Pebas and Nauta formations placed the local observations into a continental perspective and suggests that the whole Pebas-Nauta system was a probably shallow (some tens of metres at maximum), brackish- to freshwater, tidally-influenced epicontinental embayment with a probable semi-diurnal to mixed tidal regime and a microtidal range, surrounded by continental environments such as forest floors, lagoons, rivers and their flood plains, and lakes.
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Merten aluesuunnittelu on keskeinen osa komission sinisen kasvun strategiaa ja EU:n yhdennettyä meripolitiikkaa. Euroopan parla-mentti on hiljattain hyväksynyt merten aluesuunnittelua koskevan direktiivin, jonka tarkoituksena on auttaa EU-maita koordinoimaan paremmin merellä toteutettavia toimia ja varmistaa, että toimet ovat tehokkaita ja ekologisesti kestäviä. Rannikko- ja merialueilla samasta tilasta ja resursseista kilpailevat monenlaiset toimet: kalastusalueet, vesiviljelylaitokset ja merten suojelualueet, meri-infrastruktuurit kuten kaapelit, putket ja laivaväylät sekä öljy- ja kaasulaitokset ja tuulivoimalat. Uusi direktiivi auttaa välttämään näinkin erilaisten käyttötarkoitusten välisiä potentiaalisia ristiriitoja ja luomaan vakaan toimintaympäristön, joka houkuttelee sijoittajia ja edistää näin kestävää kasvua. Suunnittelulla myös vähennetään nykyistä ylisääntelyä ja hallinnollisia kiemuroita. Moni toimet edellyttävät lupaa tai lisenssiä jotta ne saisivat toimia merialueilla ja viranomaiset vaativat usein että hakija suorittaa ympä-ristövahinkoarvioinnin (YVA), joka viranomaiset arvioivat ennen lupaa myönnetään. Oppaan tarkoitus on helpottaa hakijan YVA läpivienti tai hankinta tarjoamalla yleiskatsausta menetelmistä meriympäristön tutkimiseen ja niiden sopivuutta eri tarkoituksiin.
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Shallow coastal areas are dynamic habitats that are affected by a variety of abiotic and biotic factors. In addition to the natural environmental stress, estuarine and coastal seagrass ecosystems are exposed to effects of climate change and other anthropogenic impacts. In this thesis the effect of different abiotic (shading stress, salinity and temperature) and biotic stressors (presence of co-occurring species) and different levels and combinations of stressors on the performance and survival of eelgrass (Zostera marina) was assessed. To investigate the importance of scale for stress responses, varying levels of biological organization (genotype, life stage, population and plant community) were studied in field and aquarium experiments. Light limitation, decreased salinity and increased temperature affected eelgrass performance negatively in papers I, II and III, respectively. While co-occurring plant species had no notable effect on eelgrass in paper IV, the presence of eelgrass increased the biomass of Potamogeton perfoliatus. The findings in papers II and III confirmed that more extreme levels of salinity and temperature had stronger impacts on plant performance compared to intermediate levels, but intermediate levels also had more severe effects on plants when they were exposed to several stressors, as illustrated in paper II. Thus, multiple stressors had negative synergetic effects. The results in papers I, II and III indicate that future changes in light climate, salinity and temperature can have serious impacts on eelgrass performance and survival. Stress responses were found to vary among genotypes, life stages and populations in papers I, II and III, respectively, emphasizing the importance of study scale. The results demonstrate that while stress in general affects seagrass productivity negatively, the severity of effects can vary substantially depending on the studied scale or level of biological organization. Eelgrass genotypes can differ in their stress and recovery processes, as observed in paper I. In paper II, eelgrass seedlings were less prone to abiotic stress compared to adult plants, but stress also decreased their survival considerably. This indicates that recruitment and re-colonization through seeds might be threatened in the future. Variation among population responses observed in paper III indicates that long-term local adaptation under differing selection pressures has caused divergence in salinity tolerance between Baltic eelgrass populations. This variability in stress tolerance observed in papers I and III suggests that some eelgrass genotypes and populations have a better capacity to adapt to changes and survive in a changing environment. Multiple stressors and biological level-specific responses demonstrate the uncertainty in predicting eelgrass responses in a changing environment. As eelgrass populations may differ in their stress tolerance both within and across regions, conservation strategies at both local and regional scales are urgently needed in order to ensure the survival of these important ecosystems.
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Julkaisussa: Terzo volume delle navigationi et viaggi raccolto gia da M. Gio. Battista Ramusio nel quale si contengono
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Nimeketiedot nimiönkehyksissä
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Kartta kuuluu A. E. Nordenskiöldin kokoelmaan
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Kartta kuuluu A. E. Nordenskiöldin kokoelmaan
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Kartta kuuluu A. E. Nordenskiöldin kokoelmaan