Search results for "Ocean"

Warming and acidification effects on biofilm/grazer interaction in an early-stage rocky intertidal community

2016

Anthropogenic carbon dioxide (CO2) emissions are increasing greenhouse effects and changing seawater carbonate chemistry, leading to ocean warming and acidification. Increasing temperature and decreasing seawater pH can potentially interact to cause changes in species interactions and community shifts. To understand how ocean warming and acidification may affect the early stages of an intertidal community in the Mediterranean, we set up an in situ experiment and assessed potential changes in grazer density andbiofilm composition by manipulating temperature on bare rock plots (10x10cm)in two locations along a natural coastal CO2 gradient (Low pH: 7.8 pH, and Ambient:8.1 pH) off Vulcano Islan…

Influence of solar and sensor angles on chlorophyll estimation for geostationary ocean color imager

2012

The impact of the solar and sensor angles on band-ratio chlorophyll concentration (Chl) estimation in Case 1 waters (open ocean) is analyzed in this work. The error range of Chl estimation due to angular variation is evaluated. The radiative transfer code Hydrolight is used for remote sensing reflectance simulation for 20 spectral bands. OC4v4 algorithm is used for Chl estimation. The results indicate that the error range of Chl estimation is between -41.91% and +46.15% when Chl range is from 0.0425 mg/m 3 to 10.6685 mg/m 3 and the solar and sensor zenith angles vary between 0 and 80°. This study provides a reference to determine the effective observation area of a future multispectral or h…

PERANAN GELOMBANG PANJANG TERHADAP SIRKULASI ARUS GLOBAL

2008

The global surface current system forms a large scala current circulation pattern known as gyra, which occurs in the Pasific, Hindia, and Atlantic oceans. At the nothern equator, the gyra circulation is counterclockwise, while it is anti counterclockwise at the southern equator. The trade wind crossing the Equatorial ocean causes a different slope and influences the slope form. The response of the sea level slope can be only described by the sea level pertubation concept that the disturbance moves as pulse wave which travel alongside equatorial ocean. The effects of the Rossby and Kelvin waves propagation on the ocean circulation depend on the lattitude. At the middle and high lattitudes, t…

Morpho-sedimentary setting and evolution of Marettimo Valley (Egadi Islands, Sicily) during middle-late Quaternary: interaction between sea level cha…

2017

We present morphological and stratigraphic results coming from surveys acquired in a NNW-SSE trending submarine depression (Marettimo Valley) located in the Egadi Islands (western Sicily offshore). In this area the seafloor is characterized by both depositional and erosional features generated under a variety of sedimentary processes. We identified two seismic facies units that are correlatable to: A) the progradation of shallow water (coastal to offshore) deposits during forced-regression sedimentary process, and B) contourite drifts emplaced by geostrophic currents through the Marettimo Valley. This unusual association of very shallow water contourites and shelf margin deposits originates…

The synergy of water quality and sea surface currents data in determining the spatio-temporal evolution of large-scale circulation features

2014

Chlorophyll-a (CHL-a) and Sea Surface Temperature (SST), amongst others, are proxies or indicators for water quality and can be easily retrieved synoptically and almost in near-real time through satellite remote-sensing. However, as they evolve in space and time in response to winds and currents, a full resolution of the temporal and spatial scales of these latters is required and their influence in shaping the distribution of water quality parameters needs to be assessed. While providing synoptic views and revealing mesoscale features, satellites suffer, indeed, from inadequate representation of sub-grid physical processes and lack of temporal resolution. Conventional point-wise measuremen…

Record of latest Barremian-Cenomanian environmental change in tectonically controlled depressions from the Jura-Burgundy threshold (Jura Mountains, e…

2019

The area of the western Jura Mountains constitutes the former Jura-Burgundy threshold between the Tethys Ocean and the epicontinental Paris Basin Sea. During the Barremian, the area was covered by a shallow-water Urgonian carbonate platform. Tectonic processes influenced the architecture of the Urgonian platform and were notably responsible for the formation of fault-related depressions on top of the Urgonian series, which were subsequently transformed into incised valleys and then to marine depocenters. Their sedimentary infills are mostly represented by the Perte-du-Rhône Formation and record stepwise environmental change on the innermost platform, which was strongly influenced by the nea…

Evolution de la circulation oécanique profonde durant le Crétacé : apport des isotopes du néodyme

2014

The Cretaceous is depicted as the warmest period of the last 300 Ma. The oceanic circulation and location of the source zones of deep-waters are essential to understand the role of oceans in the evolution of the climate during the Cretaceous, yet they remain unclear for this period. The neodymium (Nd) isotopes are used to track oceanic circulation and exchanges between water masses, in both past and modern oceans. The Nd isotope composition (εNd) in the ocean is related to the nature of the surrounding continental landmasses. The oceanic currents transport this isotopic signature, thus every oceanic basin acquires a singular εNd. Unequivocal interpretations of the Cretaceous seawater εNd va…

L'Oceania francofona: tra tradizione e innovazione

2018

Le isole francofone dell’Oceano Pacifico – arcipelago della Polinesia francese, Nuova Caledonia, Wallis e Futuna, Vanuatu – sono caratterizzate dalla profonda variegatura della loro diversità storica e politica. Se alcuni territori sono indipendenti, altri hanno subìto o subiscono il controllo statunitense, francese, inglese, neo-zelandese, australiano e cileno. Si tratta di un’area che soltanto forzatamente può essere definita francofila e francofona dal momento che, dal punto di vista demografico, queste isole ospitano soltanto il 2,5% della popolazione totale dell’Oceania che conta su una maggioranza di anglofoni; e che si registra la presenza, accanto alla lingua francese, di ben altre …

Vertical stratification patterns of methanotrophs and their genetic controllers in water columns of oxygen-stratified boreal lakes

2021

ABSTRACT The vertical structuring of methanotrophic communities and its genetic controllers remain understudied in the water columns of oxygen-stratified lakes. Therefore, we used 16S rRNA gene sequencing to study the vertical stratification patterns of methanotrophs in two boreal lakes, Lake Kuivajärvi and Lake Lovojärvi. Furthermore, metagenomic analyses were performed to assess the genomic characteristics of methanotrophs in Lovojärvi and the previously studied Lake Alinen Mustajärvi. The methanotroph communities were vertically structured along the oxygen gradient. Alphaproteobacterial methanotrophs preferred oxic water layers, while Methylococcales methanotrophs, consisting of putative…

Composizione aminoacidica degli occhi di piccoli pesci pelagici in relazione ai processi oceanografici negli habitat di deposizione

Studio della valutare della composizione aminoacidica degli occhi di piccoli pesci pelagici in relazione ai processi oceanografici negli habitat di deposizione. La scelta di proporre uno studio sulla composizione aminoacidica degli occhi di E. encrasicolus è stata suggerita da studi pregressi che ne hanno evidenziato la specificità alla specie. In particolare, le misurazioni morfometriche e le analisi della composizione aminoacidica (AAC), degli enzimi, dei lipidi e carboidrati effettuati sulle larve di acciuga, hanno permesso di valutare se le diverse caratteristiche ambientali delle due aree possono influenzare le larve di Engraulis encrasicolus all’interno del Canale di Sicilia. Si tratt…