The distribution of phosphate in sediments of the Johnstone River catchment-estuary system, North Queensland, Australia

This paper presents results from a preliminary assessment of phosphate-loaded sediment occurrence and distribution of the Johnstone Rivers system, in the Cairns section of the Great Barrier Reef Marine Park. Total PO4 concentrations in channel sediments show a substantial increase from rainforest to agricultural settings and inorganic PO4 concentrations are much higher in the tributaries draining agricultural land than in either main river. It was also found that total PO4 concentrations are much higher in the dry season than in the wet season. The results of this study indicate that agricultural practices have a noticeable influence on the PO4 content of riverine and estuarine sediment of the Johnstone Rivers. Despite this, the estuarine, offshore and reef sediment data suggest that the phosphate loss from agricultural land in the Johnstone Rivers catchment is unlikely to affect the nutrient status of the Great Barrier Reef. Reworked, fine-grained phosphate-bearing sediment may, however, have an impact on nearshore marine ecosystems

Re-examination of the temperature-dependent relationship between delta O-18 (diatoms) and delta O-18 (lake water) and implications for paleoclimate inferences

The oxygen isotope composition (delta O-18) of diatoms is commonly used for paleoclimate reconstruction. There is, however, no consensus regarding the equilibrium isotopic fractionation factor between diatom silica and the water in which it is precipitated. We re-examined the temperature-dependent relationship between delta O-18(diatoms) and delta O-18(lake water) from Lake Annecy (France). A temperature coefficient of -0.16aEuro degrees/A degrees C (R (2) = 0.51) was determined, supporting findings from previous calibration studies. However, regression lines obtained from different calibration studies, though displaying similar slopes, were shifted. In this manuscript, we propose that several factors, including selected variables (temperature, delta O-18(lake water)), analytical techniques, the impact of diagenetic processes and biological effects, may influence the silica-water fractionation factor for diatom silica. The similar magnitude of the diatom-temperature coefficients determined across studies is promising, supporting its use as a valuable tool for interpreting variations in delta O-18 values from fossil lacustrine diatoms in temperate lakes. With respect to paleoclimatic applications, the temperature-dependent relationship yielded uncertainties of +/- 3A degrees C on reconstructed temperatures and +/- 0.5aEuro degrees on delta O-18(lake water)

Cyclotella petenensis and Cyclotella cassandrae, two new fossil diatoms from Pleistocene sediments of Lake Peten-Itza, Guatemala, Central America

While analyzing the fossil diatom flora in one of the longest paleolimnological records (core PI-6) from Lake Peten-Itza, lowland Guatemala, we encountered Aulacoseira Thwaites, Cyclotella (Kutzing) and Discostella (Cleve & Grunow) Houk & Klee species appearing successively in the record. Among them, two new species that are assigned to the genus Cyclotella are described herein. Cyclotella petenensis sp. nov. is characterised by a coarse striation marked by a shadow line and a tangentially undulate central area with an arc of central fultoportulae. Cyclotella cassandrae sp. nov. has an elliptically shaped valve, coarse striae and a scattered ring of central fultoportulae in the central area. Classification and differences to similar taxa in the genus Cyclotella are discussed

Concept for Trusted Personal Devices in a Mobile and Networked Environment

In this article we present a concept for Trusted Personal Devices, which are intended to be the common platform for the next generation of Smart Cards and other secure devices in mobile and networked environments. The concept is based on a classification of technical profiles for different potential TPD form factors and applications. Requirements coming from various application areas are considered. A number of use cases have been defined to show innovative features of the TPD. Highlights are the support of Internet connectivity and Web server functionality in a secure and reliable way. In addition, trust establishment and privacy issues are especially considered in the design

Population genomics and haplotype analysis in spelt and bread wheat identifies a gene regulating glume color

The cloning of agriculturally important genes is often complicated by haplotype variation across crop cultivars. Access to pan-genome information greatly facilitates the assessment of structural variations and rapid candidate gene identification. Here, we identified the red glume 1 (Rg-B1) gene using association genetics and haplotype analyses in ten reference grade wheat genomes. Glume color is an important trait to characterize wheat cultivars. Red glumes are frequent among Central European spelt, a dominant wheat subspecies in Europe before the 20th century. We used genotyping-by-sequencing to characterize a global diversity panel of 267 spelt accessions, which provided evidence for two independent introductions of spelt into Europe. A single region at the Rg-B1 locus on chromosome 1BS was associated with glume color in the diversity panel. Haplotype comparisons across ten high-quality wheat genomes revealed a MYB transcription factor as candidate gene. We found extensive haplotype variation across the ten cultivars, with a particular group of MYB alleles that was conserved in red glume wheat cultivars. Genetic mapping and transient infiltration experiments allowed us to validate this particular MYB transcription factor variants. Our study demonstrates the value of multiple high-quality genomes to rapidly resolve copy number and haplotype variations in regions controlling agriculturally important traits

5000 years of lacustrine ecosystem changes from Lake Petit (Southern Alps, 2200m a.s.l.) : regime shift and resilience of algal communities

Sediments from Lake Petit (2200m a.s.l., Southern Alps) are particularly relevant for analysis of coupled landscape palaeoecology and palaeolimnology. Diatom assemblages, organic matter composition of sediments (total nitrogen and organic carbon) and Pediastrum boryanum concentrations were obtained from a 144-cm-long core, enabling the reconstruction of the aquatic ecosystem over nearly the last 5000 cal. BP. From 4800 to 4300 cal. BP, Lake Petit was a stable diatom-productive water body dominated by alkaliphilous diatoms (Staurosirella pinnata). During this period, nutrients and cations were supplied by the chemical weathering of podzols that developed under conifer woodlands. This overall stability was suddenly interrupted at 4200 cal. BP by a major detrital pulse that was probably climate linked (4200 cal. BP event) and that triggered a drop in diatom productivity and diversity. From 4100 to 2400 cal. BP, diatom productivity progressively decreased, whereas Pediastrum developed. Diatom assemblages were more diversified (predominance of Pseudostaurosira robusta, P. brevistriata and P. pseudoconstruens) and reflected a regime of continuous erosion, whereas slopes were colonised by grazed grasslands. Finally, from 2400 cal. BP to the present day, diatom assemblages reveal a slight acidification and nutrient enrichment of waters concomitant with increasing human pressure in the catchment. These results demonstrate the close links between ecosystems and the ready propagation of disturbances throughout watersheds that might lead to abrupt regime shifts in such alpine environments

I-n-Atei palaeolake documents past environmental changes in central Sahara at the time of the "Green Sahara" : charcoal, carbon isotope and diatom records

During the 'Green Sahara event', water bodies developed throughout the Sahara and Sahel, reflecting the enhanced influence of the Atlantic monsoon rainfall. Major lakes then dried out between 6.5 and 3.5 ka. This study investigates land cover change and lacustrine environment during the Holocene at I-n-Atei, Southern Algeria, a desert region lying in the hyperarid core of the Sahara. This site is remarkable by its extent (up to 80 km(2)) and by the exceptional preservation and thickness of the lacustrine deposits (7.2 m). I-n-Atei was a lake from 11 to 7.4 ka, then it dried out and left place to a swampy environment. Charcoal concentrations show that the surroundings of the lake were vegetated throughout the wet period with two short phases of possible vegetation deterioration associated with a lowering of the lake level at 93 and 82 ka, coeval with well-known dry events in the tropics. The stable carbon isotope record reflects the penetration of C4 herbaceous populations in replacement of the original 0, typical of the regional vegetation at the time of the maximum lake expansion. The delta C-13 of charcoals increase non-linearly with the C-14-based ages from -24.5 parts per thousand to -13.0 parts per thousand. (V-PDB). Assuming that these extreme values sample both C3 and C4 plant end-members, mass balance calculations suggest that C3 were replaced by C4 plants according to an exponential decay law with a half-life (t(1/2)) of 850 +/- 110 years. The replacement of C3 by C4 plants occurred in two main steps: a mixed C3-C4 vegetation of "wooded grassland" type was present from 10 ka to 8.4 ka while a C4 exclusive vegetation developed after 8.4 ka. After the end of the lacustrine phase a catastrophic event (flooding?) provoked the lifting of most of the lacustrine deposits and their re-deposition above the lacustrine sequence