Search results for "Temperate"
showing 10 items of 193 documents
Metacommunities from bacteria to birds: stronger environmental selection in mediterranean than in tropical ponds
2021
AbstractThe metacommunity concept provides a theoretical framework that aims at explaining organism distributions by a combination of environmental filtering, dispersal and drift. With the development of statistical tools to quantify and partially isolate the role of each of these processes, empirical metacommunity studies have multiplied worldwide. However, few works attempt a multi-taxon approach and even fewer compare two distant biogeographical regions using the same methodology. Under this framework, we tested the expectation that temperate (mediterranean-climate) pond metacommunities would be more influenced by environmental and spatial processes than tropical ones, because of stronge…
Start of the dry season as a main determinant of inter-annual Mediterranean forest production variations
2014
Abstract Recent investigations have highlighted the dependence of Mediterranean forest production on spring rainfall. The current work introduces the concept of the start of the dry season (SDS) and performs a three-step analysis to determine the effect of SDS on Mediterranean forest production. Seven forest zones of Tuscany (Central Italy), which present differently pronounced Mediterranean features, are considered. First, a statistical analysis investigates the influence of spring water budget on forest Normalized Difference Vegetation Index (NDVI) inter-annual variations during July–August. The analysis is then extended to assess the impact of inter-annual SDS variability on forest gross…
A new lessepsian species in the western Mediterranean ( Brachidontes pharaonis Bivalvia: Mytilidae): density, resource allocation and biomass
2008
The present study reports on population dynamics and growth performance relative to a lesser known exotic invasive species ( Brachidontes pharaonis ) inhabiting the southern Mediterranean. The study was carried out in western Sicily, where B. pharaonis is present on both the submerged and emerged surfaces of a hyperhaline saltpan. Individuals were scraped, counted and measured for shell length, total weight, somatic, gonadic and shell biomass. Brachidontes pharaonis intensively colonized all hard substrates of the saltpan with annual average densities of 375 ± 293 ind. 400 cm −2 with density peaks in autumn as a function of habitat. The occurrence of juveniles was different for mediolittora…
Rarity in Chilean forest birds: which ecological and life‐history traits matter?
2007
While it is a truism that species rarity is non-randomly distributed across regions, habitats, and taxa, there is little consensus on which factors are the best predictors of low abundances and restricted geographical ranges. In this study, we evaluate the effects of ecological and life-history traits, as well as phylogeny, on rarity in the abundance and distribution of land birds inhabiting forest habitats in the Mediterranean and temperate regions of Chile. We use data on abundance collected at 16 sites and data on latitudinal distribution obtained from a literature compilation. Statistical analyses were based on multiple regression and multivariate models. We used Signed Mantel test to a…
Modelling dendro-anthracological parameters with dendrochronological reference datasets: interrogating the applicability of anthraco-typology to asse…
2020
International audience; Aleppo pine (Pinus halepensis Miller) is present in the palaeoenvironmental records of Mallorca (Balearic Islands, Western Mediterranean) since the Early Holocene. It is also documented in the archaeological charcoal analysis (aka anthracology) of early prehistoric sites, but it was especially exploited at certain sites during the Late Iron Age. However, different woodland exploitation strategies cannot be deciphered purely through the taxonomical identification of charcoal fragments, so it is difficult to assess if the presence of Aleppo pine in archaeological assemblages is due to specific social management strategies (branches and/or trunks exploitation). Anthraco…
Effect of water level and climatic factors on the radial growth of black alder
2011
Effect of water level and climatic factors on the radial growth of black alder Black alder (Alnus glutinosa (L.) Gaertn.) is a widespread tree species in Europe and the western part of the temperate climate zone. The area of forest in Latvia dominated by this tree species has substantially decreased due to wide-spread forest drainage. To predict future changes due to environmental change, it is extremely important to understand the function of ecosystems with black alder and their dynamics. Tree rings can be used as a proxy of past environmental factors. The aim of the study was to determine the effects of meteorological and hydrological factors on radial growth of black alder at two study …
Seawater carbonate chemistry and nest guarding behaviour of a temperate wrasse
2021
Organisms may respond to changing environmental conditions by adjusting their behaviour (i.e., behavioural plasticity). Ocean acidification (OA), resulting from anthropogenic emissions of carbon dioxide (CO2), is predicted to impair sensory function and behaviour of fish. However, reproductive behaviours, and parental care in particular, and their role in mediating responses to OA are presently overlooked. Here, we assessed whether the nesting male ocellated wrasse Symphodus ocellatus from sites with different CO2 concentrations showed different behaviours during their breeding season. We also investigated potential re-allocation of the time-budget towards different behavioural activities b…
Seawater carbonate chemistry and shell mineralogy, microstructure, and mechanical strength of four Mediterranean gastropod species near a CO2 seep
2017
Marine CO2 seeps allow the study of the long-term effects of elevated pCO2 (ocean acidification) on marine invertebrate biomineralization. We investigated the effects of ocean acidification on shell composition and structure in four ecologically important species of Mediterranean gastropods (two limpets, a top-shell snail, and a whelk). Individuals were sampled from three sites near a volcanic CO2 seep off Vulcano Island, Italy. The three sites represented ambient (8.15 pH), moderate (8.03 pH) and low (7.73 pH) seawater mean pH. Shell mineralogy, microstructure, and mechanical strength were examined in all four species. We found that the calcite/aragonite ratio could vary and increased sign…
Physiological advantages of dwarfing in surviving extinctions in high-CO2 oceans
2015
Excessive CO2 in the present-day ocean-atmosphere system is causing ocean acidification, and is likely to cause a severe biodiversity decline in the future, mirroring effects in many past mass extinctions. Fossil records demonstrate that organisms surviving such events were often smaller than those before, a phenomenon called the Lilliput effect. Here, we show that two gastropod species adapted to acidified seawater at shallow-water CO2 seeps were smaller than those found in normal pH conditions and had higher mass-specific energy consumption but significantly lower whole-animal metabolic energy demand. These physiological changes allowed the animals to maintain calcification and to partial…
Seawater carbonate chemistry and biogenic habitat shifts under long-term ocean acidification
2023
Experiments have shown that increasing dissolved CO2 concentrations (i.e. Ocean Acidification, OA) in marine ecosystems may act as nutrient for primary producers (e.g. fleshy algae) or a stressor for calcifying species (e.g., coralline algae, corals, molluscs). For the first time, rapid habitat dominance shifts and altered competitive replacement from a reef-forming to a non-reef-forming biogenic habitat were documented over one-year exposure to low pH/high CO2 through a transplant experiment off Vulcano Island CO2 seeps (NE Sicily, Italy). Ocean acidification decreased vermetid reefs complexity via a reduction in the reef-building species density, boosted canopy macroalgae and led to chang…