Search results for "sphere"
showing 10 items of 2121 documents
Rediscovery of Riella alatospora (Riellaceae, Sphaerocarpales), an aquatic, South African endemic liverwort previously known from a now largely trans…
2012
7 páginas, 4 figuras.
Volcanic CO2 seep geochemistry and use in understanding ocean acidification
2020
AbstractOcean acidification is one of the most dramatic effects of the massive atmospheric release of anthropogenic carbon dioxide (CO2) that has occurred since the Industrial Revolution, although its effects on marine ecosystems are not well understood. Submarine volcanic hydrothermal fields have geochemical conditions that provide opportunities to characterise the effects of elevated levels of seawater CO2 on marine life in the field. Here, we review the geochemical aspects of shallow marine CO2-rich seeps worldwide, focusing on both gas composition and water chemistry. We then describe the geochemical effects of volcanic CO2 seepage on the overlying seawater column. We also present new g…
Reciprocal interactions between plants and fluorescent pseudomonads in relation to iron in the rhizosphere
2013
SPE EA Section 15 : Engineering the rhizosphere: The "biased rhizosphere" concept Ouvrage en 2 volumes Résumé du livre : Molecular Microbial Ecology of the Rhizosphere covers current knowledge on the molecular basis of plant-microbe interactions in the rhizosphere. Also included in the book are both reviews and research-based chapters describing experimental materials and methods. Edited by a leader in the field, with contributions from authors around the world, Molecular Microbial Ecology of the Rhizosphere brings together the most up-to-date research in this expanding area, and will be a valuable resource for molecular microbiologists and plant soil scientists, as well as upper level stud…
Salinity and periodic inundation controls on the soil-plant-atmosphere continuum of gray mangroves
2017
Salinity and periodic inundation are both known to have a major role in shaping the ecohydrology of mangroves through their controls on water uptake, photosynthesis, stomatal conductance, gas-exchanges and nutrient availability. Salinity, in particular, can be considered one of the main abiotic regulating factors for halophytes and salt tolerant species, due to its influence on water use patterns and growth rate. Ecohydrological literature has rarely focused on the effects of salinity on plant transpiration, based on the fact that the terrestrial plants mostly thrive in low saline, unsaturated soils where the role of osmotic potential can be considered negligible. However, the effect of sal…
Multilocus phylogenetics of smooth clam shrimps (Branchiopoda, Laevicaudata)
2021
International audience; Laevicaudatan branchiopods, also called ‘smooth clam shrimps’ or ’pea shrimps’, are rare crustaceans found exclusively in temporary, small freshwater bodies, which stay dry most of the year. Only 42 laevicaudatan species have been described so far, 90% of which belong to the genus Lynceus. The first multilocus phylogeny of the group is provided here, based on 15 Lynceus species from North and South America, Europe, Africa, Asia, Australia and New Caledonia and using nine molecular markers (two mitochondrial and seven nuclear genes, including newly designed primers). Genetic data suggest populations of Lynceus brachyurus from Europe and North America to represent a co…
Antarctic, Sub-Antarctic and cold temperate echinoid database
2012
6 pages; International audience; This database includes spatial data of Antarctic, Sub-Antarctic and cold temperate echinoid distribution (Echinodermata: Echinoidea) collected during many oceanographic campaigns led in the Southern Hemisphere from 1872 to 2010. The dataset lists occurrence data of echinoid distribution south of 35°S latitude, together with information on taxonomy (from species to genus level), sampling sources (cruise ID, sampling dates, ship names) and sampling sites (geographic coordinates and depth). Echinoid occurrence data were compiled from the Antarctic Echinoid Database (David et al. 2005a), which integrates records from oceanographic cruises led in the Southern Oce…
Shift in Tuna Catches due to Ocean Warming.
2017
Ocean warming is already affecting global fisheries with an increasing dominance of catches of warmer water species at higher latitudes and lower catches of tropical and subtropical species in the tropics. Tuna distributions are highly conditioned by sea temperature, for this reason and their worldwide distribution, their populations may be a good indicator of the effect of climate change on global fisheries. This study shows the shift of tuna catches in subtropical latitudes on a global scale. From 1965 to 2011, the percentage of tropical tuna in longliner catches exhibited a significantly increasing trend in a study area that included subtropical regions of the Atlantic and western Pacifi…
Trans-equatorial migration routes, staging sites and wintering areas of a High-Arctic avian predator: the Long-tailed Skua (Stercorarius longicaudus).
2013
The Long-tailed Skua, a small (,300 g) Arctic-breeding predator and seabird, is a functionally very important component of the Arctic vertebrate communities in summer, but little is known about its migration and winter distribution. We used lightlevel geolocators to track the annual movements of eight adult birds breeding in north-east Greenland (n = 3) and Svalbard (n = 5). All birds wintered in the Southern Hemisphere (mean arrival-departure dates on wintering grounds: 24 October-21 March): five along the south-west coast of Africa (0–40uS, 0–15uE), in the productive Benguela upwelling, and three further south (30–40uS, 0–50uE), in an area extending into the south-west Indian Ocean. Diffe…
Interannual memory effects for spring NDVI in semi-arid South Africa
2008
[1] Almost 20 years of Normalized Difference Vegetative Index (NDVI) and precipitation (PPT) data are analysed to better understand the interannual memory effects on vegetation dynamics observed at regional scales in Southern Africa (SA). The study focuses on a semi-arid region (25°S–31°S; 21°E–26°E) during the austral early summer (September–December). The memory effects are examined using simple statistical approaches (linear correlations and regressions) which require the definition of an early summer vegetation predictand (December NDVI minus September NDVI) and a consistent set of potential predictors (rainfall amount, number of rainy days, rainfall intensity, NDVI and Rain-Use-Efficie…
Defoliation-induced changes in carbon allocation and root soluble carbon concentration in field-grown Lolium perenne plants: do they affect carbon av…
2005
Summary 1It is hypothesized that defoliation-induced changes in plant carbon allocation and root soluble C concentration modify rhizosphere C availability and, further, the abundance and activity of soil microbes and their grazers. To test this hypothesis, field-grown Lolium perenne swards were defoliated twice during their second growing season at two nitrogen availabilities (added N or no added N). Plant, soil and microbial attributes were measured 2 and 4 days after the last defoliation, and nematode abundance was measured 6 days after the last defoliation. 2Defoliation decreased shoot production in plots where N was added, but had no significant effect in plots where N was not added. Ro…