The Influence of the Zebra Mussel (Dreisena Polymorhpa) on Magnesium and Calcium Concentration in Water

In this study we examined changes in magnesium and calcium ion concentrations depending on Zebra Mussel biomass, pH values and temperature. We performed field experiments in years with different weather conditions using twelve 200 litre polycarbonate containers filled with 150 litres of non-filtered water from lowland, eutrophic reservoirs. Three treatments of the experiment were represented by: Phyto control with non-filtered water, Phyto+Dreis A with Zebra Mussel biomass of 500 g/m2, and Phyto+Dreis B with Zebra Mussel biomass of 1.000 g/m2. Magnesium and calcium ions concentrations were analyzed on an ion chromatograph (Dionex-1000). Results indicated a significant reduction in magnesium and calcium ion concentrations by Zebra Mussels (independent of mussel biomass), especially in the year with higher and more stable average temperatures. Mg concentration was significantly negatively correlated with temperature in this year. In both years of study the magnesium and calcium ion concentrations were negatively correlated with pH. Analyses of the Zebra Mussel's impact on magnesium and calcium loss from water, linked with the influence of physical factors (temperature and pH), may be valuable for the management of invaded ecosystems

A new find of mammoth tusk in loess-like sediments of the Zakliczyn Basin (Outer Western Carpathians, Poland)

In June 2007, in a valley side of a small stream close to Janowice in the Western Outer Carpathians of Poland, a 1.8 m long mammoth tusk was found within loamy-debris solifluction sediments, ca. 1 m thick. These discordantly overlie a 4-m-high strath built up of steeply dipping sandstones of the Krosno beds of the Skole Nappe, being in turn covered by 7.5-m-hick loessial silts and loess-like slopewash sediments. The latter are overlain at the top by another solifluction cover, ca. 1.5 m thick. The mammoth tusk belonged to an adult animal, probably 30-60 years old. The succession of malacofaunistic assemblages within loess-like sediments indicates a cold, polar climate, and an environment resembling tundra developed upon moderately moist substratum during the last glacial stage. The lower part of malacological sequence enriched in mesophile species probably refers to the Vistulian (Weichselian) interpleniglacial period. The middle part, indicative of more dry habitats, can be associated with the younger Pleniglacial, whereas the top part should represent the terminal phase of the latter. Sediments bearing the mammoth tusk were probably deposited at the turn of the Vistulian older Pleniglacial and Interpleniglacial time

Nonreceding hare lines: genetic continuity since the Late Pleistocene in European mountain hares (Lepus timidus)

Throughout time, climate changes have caused substantial rearrangements of habitats which have alternately promoted and disfavoured different types of taxa. At first glance, the mountain hare (Lepus timidus) shows the typical hallmarks of a cold-adapted species that has retreated to refugia since the onset of the current Holocene interglacial. In contrary to expectations, however, the species has a high contemporary genetic diversity with no clear differentiation between geographically isolated populations. In order to clarify the phylogeographic history of European mountain hares, we here analysed ancient DNA from the glacial populations that inhabited the previous midlatitude European tundra region. Our results reveal that the Ice Age hares had similar levels of genetic variation and lack of geographic structure as observed today, and the ancient samples were intermingled with modern individuals throughout the reconstructed evolutionary tree. This suggest a temporal genetic continuity in Europe, where the mountain hares were able to keep pace with the rapid changes at the last glacial/interglacial transition, and successfully track their shifting habitat to northern and alpine regions. Further, the temporal demographic analyses showed that the species’ population size in Europe appear to have been tightly linked with palaeoclimatic fluctuations, with increases and declines occurring during periods of global cooling and warming, respectively. Taken together, our results suggest that neither habitat shifts nor demographic fluctuations have had any substantial impact on the genetic diversity of European mountain hares. This remarkable resilience, which contrasts to a majority of previously investigated cold-adapted species, is likely due to its generalist nature which makes it less vulnerable to environmental changes

Taphonomy of Pleistocene large mammal remains in the deposits of river Raba, southern Poland

An assemblage of 120 mammal remains of Pleistocene age has been collected from the fluvial deposits of river Raba at a gravel pit in the village of Targowisko, 30 km east of Kraków, southern Poland. Nearly 100 remains represent woolly mammoth Mammuthus primigenius. Other remains belong to four or five such mammal species as horse Equus ferus, woolly rhinoceros Coelodonta antiquitatis, red deer Cervus elaphus and steppe bison Bison priscus or aurochs Bos primigenius. Pleistocene coarse-grained deposits containing isolated bones, teeth and tusks occur in the lowermost part of the fluvial succession in the open pit, presently inundated by groundwater. The surfaces of the majority of bones and teeth show abrasion damages by fluvial transport, including their rounding and smoothing as well as scratches and grooves. Traces of carnivore activity are visible on mammoth and horse bones. The location, dimension and shape of these marks suggest wolf or cave hyena gnawing