Search results for "Systematic"
showing 10 items of 7608 documents
Structural variables drive the distribution of the sensitive lichen Lobaria pulmonaria in Mediterranean old-growth forests
2015
a b s t r a c t We tested the hypothesis that structural variables related to old-growth features affect the distribution of Lobaria pulmonaria in a Mediterranean National Park of Italy. A total of 36 plots, with old-growth characteristics and representing overall three forest types (beech- oak- and mixed- forests) were studied. The lichen was absent in about half of the sites, suggesting that the selection of old-growth forests based solely on structural features is not sufficient to predict the presence of this species, which therefore proves to be rather sensitive and selective. Its abundance was related to high tree circumference and basal area, and to availability of deadwood, confirmi…
Detailed subglacial topography and drumlins at the marginal zone of Múlajökull outlet glacier, central Iceland: Evidence from low frequency GPR data
2016
Abstract New ground penetrating radar (GPR) observations on the Mulajokull surge-type outlet glacier, central Iceland, are presented. Overall 10.5 km of GPR profile lines were recorded parallel to the glacier margin in August, 2015. Detailed GPR investigations combined with high-accuracy GPS measurements allowed to build a high-resolution model of the subglacial topography. We provide new evidence of streamlined ridges beneath Mulajokull’s marginal zone interpreted as drumlins and show the location of the upper edge of the drumlin field. This discovery improves understanding of the location, morphology and development of drumlins as other geophysical observations of subglacial bedforms bene…
Subsurface swimming and stationary diving are metabolically cheap in adult Pacific walruses (Odobenus rosmarus divergens).
2021
ABSTRACT Walruses rely on sea-ice to efficiently forage and rest between diving bouts while maintaining proximity to prime foraging habitat. Recent declines in summer sea ice have resulted in walruses hauling out on land where they have to travel farther to access productive benthic habitat while potentially increasing energetic costs. Despite the need to better understand the impact of sea ice loss on energy expenditure, knowledge about metabolic demands of specific behaviours in walruses is scarce. In the present study, 3 adult female Pacific walruses (Odobenus rosmarus divergens) housed in professional care participated in flow-through respirometry trials to measure metabolic rates while…
Relation between climatic fluctuation and morphological variability in Microtus (Terricola) grafi (Arvicolinae, Rodentia) from Bacho Kiro (Bulgaria, …
2004
Morphological variability within the species Microtus (Terricola) grafi is investigated in relation to the parameters of time and climate. Microtus (Terricola) grafi has been described from the Upper Pleistocene cave of Bacho Kiro (Bulgaria), which has yielded numerous teeth from several levels reflecting climatic fluctuations. The first lower molars are analyzed by 23 biometric variables so as to quantify tooth shape and its variation with time and climate. This morphological analysis reveals a number of shape indexes reflecting whether an individual lived in warm or cold conditions. The most significant result is that individuals living in warm conditions exhibit the more primitive featur…
Listado taxonómico comentado de los Capitélidos (Annelida, Polychaeta) de la península Iberica, islas Chafarinas, Baleares y Canarias
2013
[EN] The present annotated checklist has been elaborated after revision of preserved materials (from the Museo Nacional de Ciencias Naturales, Madrid and the reference collection of the Marine Biology Laboratory of the University of Valencia) and published literature related to capitellids from the Iberian Peninsula, Chafarinas, Balearic and Canary Islands. Twenty-four species and subspecies belonging to thirteen genera are recognized as valid taxa. With this checklist we include some taxonomic details and information on distribution at both global and regional levels. This work includes the setal formula and diagrammatic representation of capitellid taxa treated in this study.
LA-ICP-MS analyses on coral growth increments reveal heavy winter rain in the Eastern Mediterranean at 9 Ma
2009
Abstract Sediment particles incorporated into coral skeletons reflect variation in composition and amount of suspended material in ambient water during coral growth. They can be used to identify periods of enhanced storm frequency and associated freshwater discharge. Tortonian (Late Miocene) Porites corals from Crete (Aegean Sea, Eastern Mediterranean) show pronounced annual density bands in X-ray photographs. δ18O compositional variability reflects the annual banding equivalent with a ~ 7 °C annual sea surface temperature (SST) cycle over a seven-year period. Fine sediment particles are concentrated in layers with skeletal porosity parallel to growth increments. Variations in the chemical …
EnvDB, a database for describing the environmental distribution of prokaryotic taxa.
2009
Summary EnvDB is a database that classifies the environmental samples and their associated 16S rDNA sequences currently stored in GenBank. The samples were cat- egorized in a three-level, hierarchical classification of media: the five upper levels (terrestrial, aquatic, thermal, host-associated and other) are further decomposed in 20 intermediate (such as marine, marine sediments, freshwater, soil, gut, etc.) and 47 lower levels (for instance, soil is further decomposed in forest, agricultural, wetlands, grasslands, tropical, arid, etc.). Each sample was also characterized with nine environmental features: polluted, diseased (for clinical samples), acidic, alkaline, hot environment, cold en…
Unravelling the bacterial diversity found in the semi-arid Tablas de Daimiel National Park wetland (central Spain)
2010
Our knowledge of microbial diversity in the environment is still limited, and there are many species as yet unidentified in both soil and water. Studies of the microbial diversity of wetland ecosystems have been neglected for years, as is the case of Tablas de Daimiel National Park (TDNP), a Spanish semi-arid wetland system of international importance in terms of waterfowl. We report the bacterial diversity of water column, sediment (upper and lower layers) and biofilm samples from the TDNP system using a 16S rRNA gene library approach. A sequence comparison of the 703 clones obtained revealed a number of bacterial phylogroups unreported to date. Bacterial diversity was high (Shannon values…
Diel variability in counts of reef fishes and its implications for monitoring
2006
Studies of reef fish assemblages in space rarely consider the effects of temporal variability on spatial comparisons, and when they do, usually examine timescales of months to years. The nature of fish monitoring surveys is such that particular locations may be surveyed at one time of day, and surveys designed to establish the degree of spatial variability in assemblages may be confounded if the order of sampling within treatments is not randomised with respect to time of day. In this study, we tested the degree of temporal variability in temperate reef fish counts at the same sites in New Zealand and Italy, within and between days. Repeated counts separated by months returned quite differe…
Byers Peninsula: A reference site for coastal, terrestrial and limnetic ecosystem studies in maritime Antarctica
2009
Abstract This article describes the development of an international and multidisciplinary project funded by the Spanish Polar Programme on Byers Peninsula (Livingston Island, South Shetlands). The project adopted Byers Peninsula as an international reference site for coastal and terrestrial (including inland waters) research within the framework of the International Polar Year initiative. Over 30 scientists from 12 countries and 26 institutions participated in the field work, and many others participated in the processing of the samples. The main themes investigated were: Holocene changes in climate, using both lacustrine sediment cores and palaeo-nests of penguins; limnology of the lakes, …