28 research outputs found
Variation of leaf litter decomposition among rivers, lagoons and sea: an experiment from Corfu island (Greece)
In aquatic ecosystems, the decomposition of organic detritus represents one of the most important
ecosystem functions, which support complex detritus-based food webs that determine the critical balance
between carbon mineralization and sequestration. The performance of the decomposition process is usually
expressed as rate of decomposition, being a synthetic measure that take into account both abiotic and biotic
factors. Decomposition rates have been also applied to evaluate the ecological status in terms of ecological
functionality. However, despite a growing number of studies have tested the rate of decomposition between
leaves of different riparian tree species in different aquatic ecosystems including rivers, transitional waters
and sea, no comparative study among ecosystems typology is available up to date. Here, we compare
decomposition rates from rivers, lagoons and sea of Corfu island (Greece). Five sampling sites were fixed in
each of the three of the most important rivers and lagoons; other five sampling sites were fixed in the sea
around the island. Twelve leaf packs containing 3±0.005 g of oven-dried Phragmites australis leaves were
submerged in April 2014 and retrieved in May 2014 (after 30 days). Abiotic parameters were recorded in
both sampling times. The retrieved leaf packs were cleaned and the macroinvertebrates retained were
removed, counted, identified at lower taxonomic level and weighted. Leaf pack decomposition rates were
calculated, and their variability was compared within each aquatic ecosystem, within each ecosystem
typology (river, lagoon, sea) and among ecosystem typology. The results are going to be presented on the
poster
Models of Solar Wind Structures and Their Interaction with the Earth's Space Environment
The discipline of "Space Weather" is built on the scientific foundation of solar-terrestrial physics but with a strong orientation toward applied research. Models describing the solar-terrestrial environment are therefore at the heart of this discipline, for both physical understanding of the processes involved and establishing predictive capabilities of the consequences of these processes. Depending on the requirements, purely physical models, semi-empirical or empirical models are considered to be the most appropriate. This review focuses on the interaction of solar wind disturbances with geospace. We cover interplanetary space, the Earth's magnetosphere (with the exception of radiation belt physics), the ionosphere (with the exception of radio science), the neutral atmosphere and the ground (via electromagnetic induction fields). Space weather relevant state-of-the-art physical and semi-empirical models of the various regions are reviewed. They include models for interplanetary space, its quiet state and the evolution of recurrent and transient solar perturbations (corotating interaction regions, coronal mass ejections, their interplanetary remnants, and solar energetic particle fluxes). Models of coupled large-scale solar wind-magnetosphere-ionosphere processes (global magnetohydrodynamic descriptions) and of inner magnetosphere processes (ring current dynamics) are discussed. Achievements in modeling the coupling between magnetospheric processes and the neutral and ionized upper and middle atmospheres are described. Finally we mention efforts to compile comprehensive and flexible models from selections of existing modules applicable to particular regions and conditions in interplanetary space and geospace
Multilocus phylogeny and taxonomic revision of the Hemidactylus robustus species group (Reptilia, Gekkonidae) with descriptions of three new species from Yemen and Ethiopia
The gecko genus Hemidactylus, with its 132 currently recognized species, ranks among the most species-rich reptile genera. Recent phylogenetic studies disclosed unexpectedly high genetic variability and complex biogeographic history within its arid clade distributed in the Mediterranean, Northeast Africa, Middle East and the Indian subcontinent. Particularly, the species from the Arabian Peninsula have been lately the subject of many taxonomic revisions that have resulted in the descriptions of 16 new taxa. Yet not all detected cryptic lineages have been treated taxonomically and thoroughly investigated morphologically. Based on phylogenetic analyses of two mtDNA (12S, cytb) and four nDNA (cmos, mc1r, rag1, rag2) gene fragments of a total length of 4015 bp in combination with analysis of morphological characters, we reinvestigate the systematics of the H. robustus species group consisting of the widespread H. robustus and three undescribed species, two of which occur in Southwest Yemen and one in central Ethiopia. By comparing two phylogenetic inference methods, concatenated gene trees and species-tree estimation, we reconstruct the phylogeny of the H. robustus species group. The coalescent-based species-tree estimation resulted in different tree topology than the concatenation approach, being probably a result of incomplete lineage sorting of ancestral polymorphism, suggesting that the H. robustus species group is in a stage of incipient speciation. The degree of differentiation of the characters examined within the H. robustus species group allowed us to provide a redescription of H. robustus and formally describe three new species of Hemidactylus – H. adensis sp. nov. and H. mandebensis sp. nov. from Yemen and H. awashensis sp. nov. from Ethiopia.Peer reviewe