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Depth Layers (depth + layer)

Distribution by Scientific Domains

Earth and Environmental Science	40%

Selected Abstracts

Diel vertical migration of medusae in the open Southern Adriatic Sea over a short time period (July 2003)

MARINE ECOLOGY, Issue 1 2009
Davor Lu
Abstract Diel vertical migration (DVM) of medusae was investigated at a fixed station in the oligotrophic Southern Adriatic Sea at several depths during summer (July) 2003. We hypothesized that medusan DVM is considerably influenced by environmental variables such as hydrographic features, light intensities, and potential prey densities. We used short-term repetitive sampling as an approach to detail these relationships. Of the 26 species collected, the highest abundance was in the layer between the thermocline (15 m) and 100 m depth, where Rhopalonema velatum predominated, reaching the maximum count of 93 individuals per 10 m3. Seven species were observed over a wide depth range: Solmissus albescens (15,1200 m), R. velatum (0,800 m), Persa incolorata (50,1200 m), Octophialucium funerarium (200,1200 m), Arctapodema australis (200,1200 m), Amphinema rubra (100,800 m), and Rhabdoon singulare (15,600). According to the medusan weighted mean depth (WMD) calculations, the longest DVMs were noted for the deep-sea species S. albescens, O. funerarium, and A. australis. The shallowest species, Aglaura hemistoma, was primarily non-migratory. Certain medusan assemblages were associated consistently with a particular depth layer characterized by a particular light intensity. The interplay of environmental factors and trophic relationships explains some of the features of medusan migratory patterns. These findings thus contribute to understanding the variables that determine patterns of medusan vertical migratory behavior. [source]

Fragment-Parallel Composite and Filter

COMPUTER GRAPHICS FORUM, Issue 4 2010
Anjul Patney
We present a strategy for parallelizing the composite and filter operations suitable for an order-independent rendering pipeline implemented on a modern graphics processor. Conventionally, this task is parallelized across pixels/subpixels, but serialized along individual depth layers. However, our technique extends the domain of parallelization to individual fragments (samples), avoiding a serial dependence on the number of depth layers, which can be a constraint for scenes with high depth complexity. As a result, our technique scales with the number of fragments and can sustain a consistent and predictable throughput in scenes with both low and high depth complexity, including those with a high variability of depth complexity within a single frame. We demonstrate composite/filter performance in excess of 50M fragments/sec for scenes with more than 1500 semi-transparent layers. [source]

The inherent ,safety-net' of an Acrisol: measuring and modelling retarded leaching of mineral nitrogen

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2002
D. Suprayogo
Summary The inherent features of Acrisols with their increasing clay content with depth are conducive to reducing nutrient losses by nutrient adsorption on the matrix soil surfaces. Ammonium (NH4+) and nitrate (NO3,) adsorption by a Plinthic Acrisol from Lampung, Indonesia was studied in column experiments. The peak of the H218O breakthrough occurred at 1 pore volume, whereas the median pore volumes for NH4+ and NO3, ranged from 6.4 to 6.9 and 1.1 to 1.6, respectively. The adsorption coefficients (Ka in cm3 g,1) measured were 1.81, 1.51, 1.64 and 1.47 for NH4+ and 0.03, 0.09, 0.10 and 0.17 for NO3,, respectively, in the 0,0.2, 0.2,0.4, 0.4,0.6 and 0.6,0.8 m soil depth layers. The NH4+ and NO3, adsorption coefficients derived from this study were put in to the Water, Nutrient and Light Capture in Agroforestry Systems (WaNuLCAS) model to evaluate their effect on leaching in the context of several cropping systems in the humid tropics. The resulting simulations indicate that the inherent ,safety-net' (retardation mechanism) of a shallow (0.8,1 m) Plinthic Acrisol can reduce the leaching of mineral N by between 5 and 33% (or up to 2.1 g m,2), mainly due to the NH4+ retardation factor, and that the effectiveness in reducing N leaching increases with increasing depth. However, the inherent ,safety-net' is useful only if deep-rooted plants can recover the N subsequently. [source]

Can soil seed banks contribute to the restoration of dune slacks under conservation management?

APPLIED VEGETATION SCIENCE, Issue 2 2009
Katharina Plassmann
Abstract Questions: Does the soil seed bank resemble the former early successional stages of a dune slack system more than the established later successional vegetation? Does it have the potential to contribute to the conservation of a highly endangered habitat? Location: Dune slacks at Newborough Warren, UK. Methods: The composition of the soil seed bank in two depth layers was determined using the seedling emergence method between March 2004 and April 2005. Long-term monitoring data on the floristic composition of the established vegetation were obtained from the national conservation agency, and additional monitoring was undertaken in 2003. Floristic composition, seed weights, seed longevity of component species and Ellenberg indicator values were used to compare the seed bank and established vegetation. Results: The soil seed bank was diverse and contained typical dune slack species, species of early successional stages and species of conservation interest. A comparison between the composition of the seed bank and historical data on the composition of the established vegetation showed that the seed bank reflects earlier successional stages more closely than the current aboveground vegetation. This study increases the scarce information currently available on the seed bank ecology of several species, including two orchid species. Conclusions: The soil seed bank can be expected to contribute to vegetation change after disturbance. Stimulation of germination from the seed bank through management may contribute to the conservation of both characteristic and threatened species typical of dune slacks. [source]