Search results for "State."
showing 10 items of 8943 documents
The challenge of habitat modelling for threatened low density species using heterogeneous data: The case of Cuvier’s beaked whales in the Mediterrane…
2018
We are grateful to the ACCOBAMS Secretariat for their support in this work, including a small grant for the analysis. The Mediterranean population of Cuvieŕs beaked whale (Ziphius cavirostris), a deep-diving cetacean, is genetically distinct from the Atlantic, and subject to a number of conservation threats, in particular underwater noise. It is also cryptic at the surface and relatively rare, so obtain robust knowledge on distribution and abundance presents unique challenges. Here we use multiplatform and multiyear survey data to analyse the distribution and abundance of this species across the Mediterranean Sea. We use a novel approach combining heterogeneous data gathered with different …
Macroalgal forest vs sea urchin barren: Patterns of macro-zoobenthic diversity in a large-scale Mediterranean study.
2019
Abstract The study aimed at contributing to the knowledge of alternative stable states by evaluating the differences of mobile and sessile macro-zoobenthic assemblages between sea urchin barrens and macroalgal forests in coastal Mediterranean systems considering a large spatial scale. Six sites (100 s km apart) were selected: Croatia, Montenegro, Sicily (Italy), Sardinia (Italy), Tuscany (Italy), and Balearic Islands (Spain). A total of 531 taxa, 404 mobile and 127 sessile macro-invertebrates were recorded. Overall, 496 and 201 taxa were found in macroalgal forests and in barrens, respectively. The results of this large-scale descriptive study have met the expectation of lower macrofauna co…
Cinderella's helping pigeons of the microbial world: The potential of testate amoebae for identifying cryptotephra
2016
Cryptotephra (particles <125μm) is a key record for monitoring past and current volcanic activity. However, its extraction from the host sediment and analysis is often long and difficult because of its small size. Finding a simple method to extract cryptotephra from environmental samples would therefore make its analysis much easier. We hypothesized that arcellinid testate amoebae may hold such a potential. These free-living shelled protists are among the earliest microorganisms to colonize volcanic tephra, and build their shell by agglutinating minerals from their environment. We analyzed by X-ray Spectrometry the mineral signature of tephra from the 2011 Puyehue-Cordon Caulle Volcanic Com…
Vegetation of Middle Asia – the project state of art after ten years of survey and future perspectives
2017
Middle Asia is one of the most diverse regions on earth with high endemism of vascular plants and remarkable habitat richness, mainly due to the considerable altitudinal range (300-7,500 m a.s.l.). The region is considered as one of the 34 global biodiversity hotspots. This paper presents the Vegetation of Middle Asia database (VMA; GIVD ID: AS-00-003; http://www.givd.info/ID/AS-00-003) which is the regional database that covers the area of Tajikistan, Kyrgyzstan and Uzbekistan. The database contains phytosociological relevés collected between the years 2006 and 2016 in different vegetation types with the use of the Braun-Blanquet method. The covered vegetation types include: deciduous fore…
Functional rearrangement of the light-harvesting antenna upon state transitions in a green alga
2014
AbstractState transitions in the green alga Chlamydomonas reinhardtii serve to balance excitation energy transfer to photosystem I (PSI) and to photosystem II (PSII) and possibly play a role as a photoprotective mechanism. Thus, light-harvesting complex II (LHCII) can switch between the photosystems consequently transferring more excitation energy to PSII (state 1) or to PSI (state 2) or can end up in LHCII-only domains. In this study, low-temperature (77 K) steady-state and time-resolved fluorescence measured on intact cells of Chlamydomonas reinhardtii shows that independently of the state excitation energy transfer from LHCII to PSI or to PSII occurs on two main timescales of <15 ps and …
Testing hypotheses in evolutionary ecology with imperfect detection: capture-recapture structural equation modeling.
2012
8 pages; International audience; Studying evolutionary mechanisms in natural populations often requires testing multifactorial scenarios of causality involving direct and indirect relationships among individual and environmental variables. It is also essential to account for the imperfect detection of individuals to provide unbiased demographic parameter estimates. To cope with these issues, we developed a new approach combining structural equation models with capture-recapture models (CR-SEM) that allows the investigation of competing hypotheses about individual and environmental variability observed in demographic parameters. We employ Markov chain Monte Carlo sampling in a Bayesian frame…
Measuring environmental performance in the treatment of municipal solid waste: The case of the European Union-28
2021
Abstract This paper proposes a measure of environmental performance in the treatment of municipal solid waste, which is defined as a ratio between a composite indicator of waste treated through environmentally desirable operations –recycling and recovery in our case study– and a composite indicator of waste treated through undesirable operations –landfill and incineration. Moreover, it contributes both overall and treatment-specific indicators of performance. Data Envelopment Analysis (DEA) techniques are used to compute the environmental performance indicators and they are illustrated with an empirical assessment of the environmental performance of the European Union-28 (EU-28) members in …
Leading role of the sea urchin Arbacia lixula in maintaining the barren state in southwestern Mediterranean
2011
Sympatric sea urchin species are usually considered to belong to the same grazer guild. Nevertheless, their role in community dynamics may vary due to species-specific morphological traits, feeding preferences and foraging behavior. In the Mediterranean Sea, the two species Paracentrotus lividus and Arbacia lixula co-occur in barren areas. Whereas P. lividus is usually considered responsible for creating a barren ground, the roles of the two sea urchin species in its maintenance are currently unclear. The relative and combined effects of P. lividus and A. lixula on maintaining the benthic community in the barren state were tested experimentally, using orthogonal exclusion of the two species…
Geochemical survey of Levante Bay, Vulcano Island (Italy), a natural laboratory for the study of ocean acidification
2013
Abstract Shallow submarine gas vents in Levante Bay, Vulcano Island (Italy), emit around 3.6t CO2 per day providing a natural laboratory for the study of biogeochemical processes related to seabed CO2 leaks and ocean acidification. The main physico-chemical parameters (T, pH and Eh) were measured at more than 70 stations with 40 seawater samples were collected for chemical analyses. The main gas vent area had high concentrations of dissolved hydrothermal gases, low pH and negative redox values all of which returned to normal seawater values at distances of about 400 m from the main vents. Much of the bay around the vents is corrosive to calcium carbonate; the north shore has a gradient in s…
Micropredation on sea urchins as a potential stabilizing process for rocky reefs
2012
Rocky reefs can shift from forest, a state dominated by erect algae with high biodiversity, to barren, an impoverished state dominated by encrusting algae. Sea urchins, abundant in barrens, are usually held responsible for the maintenance of this state. Predation by large fish can revert the barren state to forest by controlling sea urchin populations. However, the persistence of a community state sometimes seems to be independent from the presence of such large predators, suggesting the existence of other, unknown mechanisms ensuring their stability. Theoretical studies suggest that the settler stage of sea urchins is determinant for maintaining a given rocky reef state. In this study, we …