Biogeochemical signatures in the lichen Hypogymnia physodes in the mid Urals

Abstract Multi-element content and uranium (U) isotopes were investigated in the lichen Hypogymnia physodes (native and transplants) sampled across a 60-km transect, centred on Karabash smelter town, from Turgoyak Lake (SW) to Kyshtym (NE) to investigate the origin of U. Kyshtym was the site of a major nuclear accident in 1957. 234 U/ 238 U activity ratios in native thalli sampled during July 2001 were within the natural isotopic ratio in minerals. Uranium/thorium (U/Th) ratios were higher in native thalli towards the NE (average 0.73) than those in the SW (average 0.57). Element signatures in native thalli and transplants suggest U was derived from fossil fuel combustion from Karabash and sources lying further to the east. Systematic and significant U enrichment indicative of a nuclear fuel cycle source was not detected in any sample. Element signatures in epiphytic lichen transplants and native thalli provide a powerful method to evaluate U deposition

Ecology and biogeography of Himalayan diatoms: distribution along gradients of altitude, stream habitat and water chemistry

Himalayan streams, an important natural resource, are subject to numerous threats such as pollution and hydrological changes with deteriorating water quality in some areas. In order to develop diatom-based monitoring tools, we investigated diatom species composition at 206 sites in relation to variation in hydrochemistry, habitat characteristics (land use, shading, substrate), altitude and geographical position across a ca. 900 km east-west distance and a 4300 m altitudinal range in Nepal and north-west India. A total of 261 species were found, of which naviculoid (55), monoraphid (47), Gomphonema and fragilarioid (30), cymbelloid (26) taxa and Nitzschia (22) were most abundant. Many species were cosmopolitan, but some had restricted distributions. Of these, most were confined to the eastern Himalaya. More than one third of the species could not be identified. Richness and diversity increased in streams with higher Si concentrations and smaller substratum size, but were not correlated with altitude as a single factor. Canonical correspondence analysis and non-metric multidimensional scaling ordination analyses showed that different regions had distinct diatom assemblages. Important environmental gradients included basestatus, reflecting differences in geology, concentrations of Si (0.5-11.5 mg/L) and Na (0.2-9.0 mg/L), reflecting impacts from agriculture, and habitat, such as substratum size, land use and stream size. The importance of these factors varied in different climatic zones. Across the east-west range and altitudinal gradient hydrochemistry and habitat characteristics explained more of the variation in species composition than altitude and geographical position, but these factors were inter-correlated and their effects difficult to disentangle. Some species had restricted distributions along the altitudinal gradient, and particularly in the eastern Himalaya a change in species composition occurred most clearly at 2000 m a.s.l. Consequently, areas above and below this altitude should be considered separately when developing diatom-based monitoring methods

Post-Tsunami Recovery of Shallow Water Biota and Habitats on Thailand’s Andaman Coast

There have been very few quantitative studies of the intertidal and shallow water biota of the Andaman Coast of Thailand and thus it was very difficult to provide precise estimates of the impact of the tsunami on coastal resources. Some quantitative data from Laem Son National Park existed, having been collected by the present authors, and these indicated that the most severe impacts were on the intertidal sand beach fauna, on rocky shore assemblages and on the seaward edge of mangrove forests. Inside the forests there was heavy deposition of coarse sediment on the forest floor and this led to changes in the species composition of the infauna. Most, but not all, sea grass beds escaped serious damage. By 2008 intertidal sediment assemblages contained a similar number of individuals to that recorded before the tsunami. Pre-tsunami data indicate that open coast, estuarine and seagrasses assemblages are naturally highly variable and thus were well adapted to recovering from the tsunami disturbance. Offshore sediments lack pre-tsunami information, but they too appear to be normal. Size frequency analysis of a population of the heart urchin Brissopsis luzonicus indicate that some individuals survived the tsunami but that there is heavy domination by the first post-tsunami cohort suggesting heavy colonization of disturbed seafloor. The trees in the seaward fringe of the most exposed mangrove forests still have to recover from tsunami damage, although the benthic fauna within the forest has returned.<br/