Search results for "Spatial Distribution"
showing 10 items of 180 documents
Spatial Distribution and Abundance of Mesopelagic Fish Biomass in the Mediterranean Sea
2020
Mesopelagic fish, being in the middle of the trophic web, are important key species for the marine environment; yet limited knowledge exists about their biology and abundance. This is particularly true in the Mediterranean Sea where no regional assessment is currently undertaken regarding their biomass and/or distribution. This study evaluates spatial and temporal patterns of mesopelagic fish biomass in the 1994–2011 period. We do that for the whole Mediterranean Sea using two well-established statistical models, the Generalized Additive Model (GAM) and Random Forest (RF). Results indicate that the bathymetry played an important role in the estimation of mesopelagic fish biomass and in its …
A critical analysis of three remote sensing-based actual evapotranspiration assessment methods over sparse crops agricultural areas
2010
During last two decades the increasing availability of remotely sensed acquisitions in the thermal infrared part of the spectrum has encouraged hydrologist community to develop models and methodologies based on these kind of data. The aim of this paper is to compare three methods developed to assess the actual evapotranspiration spatial distribution by means of remote sensing data. The comparison was focused on the differences between the "single" (SEBAL) and "two" source (TSEB) surface energy balance approaches and the S-SEBI semi-empirical method. The first assumes a semiempirical internal calibration for the sensible heat flux assessment; the second uses a physically based approach in or…
Preliminary patterns of distribution and abundance of loggerhead sea turtles, Caretta caretta , around Columbretes Islands Marine Reserve, Spanish Me…
2003
Aerial surveys were conducted to estimate the abundance and distribution of loggerhead turtles (Caretta caretta) in the Columbretes Islands Marine Reserve and surrounding waters (western Mediterranean). Four surveys were carried out during 2000 and 2001, following the line transect methodology. Loggerheads appeared to be present at high densities in the area throughout the whole year, although density varied between seasons, being more abundant during the spring. Mean density in the study area was 0.322 turtles/km2 (range 0.200–0.516) and the mean abundance was 1,324 turtles (range 825–2,124). The turtles were distributed homogeneously throughout the study area, we found no difference in lo…
Environmental Metal Pollution Considered as Noise: Effects on the Spatial Distribution of Benthic Foraminifera in two Coastal Marine Areas of Sicily …
2008
We analyze the spatial distributions of two groups of benthic foraminifera (Adelosina spp. + Quinqueloculina spp. and Elphidium spp.), along Sicilian coast, and their correlation with six different heavy metals, responsible for the pollution. Samples were collected inside the Gulf of Palermo, which has a high level of pollution due to heavy metals, and along the coast of Lampedusa island (Sicily Channel, Southern Mediterranean), which is characterized by unpolluted sea waters. Because of the environmental pollution we find: (i) an anticorrelated spatial behaviour between the two groups of benthic foraminifera analyzed; (ii) an anticorrelated (correlated) spatial behaviour between the first …
Structural analysis of woody species in Mediterranean old fields.
2008
The first part of this study provides an overview on Sicilian olive systems. Subsequently, the study describes the different typologies of cultivated agroforestry systems present in South-Eastern Sicily employing olive trees in association with other Mediterranean tree species, in particular for the production of firewood, coal and animal food (downy or pubescent oak, holm oak, cork oak), but also in association with forage or grazing species (oat, barley, vetch, etc.) or cereals. The study shows that Sicilian agroforestry systems are much more diversified than it was known so far. In the second part, the study describes the spontaneous colonization processes by plants, observed in abandone…
Bioclimatology and Vegetation Series in Sicily: A Geostatistical Approach
2015
Tackling the Sicilian woody vegetation as a case-study, this work aims to verify the correspondence between Rivas-Martínez's bioclimatic units and the main vegetation series in the Mediterranean region. Following this approach, one macrobioclimate and 25 bioclimatic type belts can be recognized in Sicily. By means of a geostatistical analysis based on WorldClim data sets, cartographic models of the distribution range of each single bioclimatic unit were obtained and combined with vegetation data, in order to develop a new regional spatial framework, integrating climatic and vegetation data. Fidelity of each vegetation unit to a given climatic range was then evaluated as percent distribution…
Sea surface temperature and torrential rains in the Valencia region: modelling the role of recharge areas
2015
Abstract. Heavy rain events are frequently recorded in the Western Mediterranean causing economic losses and even human casualties. The Western Mediterranean is a deep and almost closed sea surrounded by high mountain ranges and with little exchange of water with the Atlantic ocean. A main factor in the development of torrential rains is ocean-atmosphere exchanges of heat and moisture that can potentially destabilize air masses travelling over the sea. The study of air mass trajectories previous to the rain event permits the identification of sea areas that could probably contribute to the development or intensification of rainfall. From a previous Mediterranean sea surface temperature clim…
A detailed analysis of the spatial distribution of Schöningen 13II-4 'Spear Horizon' faunal remains
2021
The Middle Pleistocene Schöningen 13II-4 'Spear Horizon' (Germany) is a key site for the study of human evolution, most notably for the discovery of Paleolithic wooden weaponry and evidence for developed hunting strategies. On the other hand, the 'Spear Horizon' offers an excellent opportunity to approach hominin spatial behavior, thanks to the richness of the archeological assemblage, its exceptional preservation, and the vast expanse of the excavated surface. Analyzing how space was used is essential for understanding hominin behavior at this unique open-air site and, from a wider perspective, for approaching how humans adapted to interglacial environments. In this article, we present an …
Different Scales of Spatial Segregation of Two Species of Feather Mites on the Wings of a Passerine Bird
2011
The "condition-specific competition hypothesis" proposes that coexistence of 2 species is possible when spatial or temporal variations in environmental conditions exist and each species responds differently to those conditions. The distribution of different species of feather mites on their hosts is known to be affected by intrinsic host factors such as structure of feathers and friction among feathers during flight, but there is also evidence that external factors such as humidity and temperature can affect mite distribution. Some feather mites have the capacity to move through the plumage rather rapidly, and within-host variation in intensity of sunlight could be one of the cues involved …
Diachronic variation in the Middle Paleolithic settlement of Abrigo de la Quebrada (Chelva, Spain)
2017
Abstract This paper compares levels IV and VIII of Abrigo de la Quebrada. The study includes knapping technique, raw material, fauna, and the spatial distribution of lithic and bone remains. Although both levels correspond to cumulative palimpsests, patterns of resource management and use of space that suggest changes in the rhythm of occupation and the functionality of the settlements can be discerned. A change in mobility patterns probably underpins the differences between these two levels of Quebrada, but assessing this hypothesis is made difficult by the lack of comparable documentation for other sites in the region.