Nach dem ersten und einzigen Fund im Jahr 1948 wurde Dolomedes plantarius zwischen 1996 und 2021 wiederholt in der nördlichen Oberlausitz (Sachsen) gefunden. Die Zufallsfunde gelangen in der Ufervegetation beziehungsweise dem Schwimmblattgürtel eines extensiv genutzten Badesees und von drei Fischteichen mit Hilfe von Kescherfängen. Alle Teiche, in denen die Art nachgewiesen werden konnte, liegen in Gebieten mit mehreren Stillgewässern und zeichnen sich durch eine strukturreiche Ufer- oder Schwimmblattvegetation aus. Die Gewässer wiesen einen hohen Nährstoffgehalt auf, der Badesee einen sehr niedrigen pH-Wert. Die Fischteiche werden im Rahmen der Bewirtschaftung regelmäßig im Herbst abgelassen. Es ist anzunehmen, dass D. plantarius die Teiche nach der Bespannung im Frühjahr von benachbarten, wasserführenden Teichen wiederbesiedelt.

Central European wet meadows are diminished by abandonment of cultivation measures, drainage, pollution, intensive agriculture and climate change during the last decades. In addition, original wet meadow communities can be threatened by immigrating neophytes. Typical invasive species in wet meadows are the steeplebushes Spiraea tomentosa and Spiraea douglasii, but their impact on the indigenous arthropod fauna is unknown. The present study therefore investigates Spiraea-induced changes in ground- and herb dwelling spiders in Spiraea sites, uncultivated meadows with interspersed Spiraea sp. and mowed meadows without Spiraea sp. using pitfall traps and sweep netting. Light intensity, vegetation height and coverage differed significantly between the Spiraea sites and the mowed meadows. In consequence, the activity density of ground-dwelling spiders was much lower in the Spiraea sites and their habitat preferences differed significantly from the two meadow types. Species preferring forests and forest edges were more abundant in invaded sites whereas specimens preferring open habitats decreased. Although the vegetation height and coverage of mowed meadows and cultivated meadows did not differ remarkably, uncultivated meadows contained less spiders of open dry habitats whereas forest species increased. In contrast, differences between herb dwelling spider assemblages of the three habitat types were not significant. Based on the results of the project, the risk of steeple bush invasion and management methods of wet meadows are discussed.

In mofette fields, natural carbon dioxide springs, organisms have to stand extreme CO2 concentrations up to 100%. These hostile conditions are spatially small-scaled and further influenced by earth tides, wind and temperature. The present project investigated the influence of increased atmospheric CO2 concentration on spiders as representatives of above-ground organisms by means of pitfall traps in three mofette fields, differing in habitat conditions in the Plesna valley, eastern Cheb Basin, Czech Republic.Among the 71 recorded spider species four were rarely found in the Czech Republic. A canonical correspondence analysis revealed significant influences of environmental parameters on the spider assemblages. Two groups of spiders are clearly distinguishable, one being positively influenced by humidity and the second by temperature. A cluster analysis showed distinct and congruent results: spider assemblages of pitfall traps at spots with a mean CO2 concentration above 7.6% grouped close together and this grouping was independent of site. At >7.6% CO2 significantly fewer individuals and species were found in comparison to areas with lower CO2 concentration. Between 2.5 and 10% CO2, spiders indicated increased CO2 concentrations much more sensitively than endogeic organisms (Nematoda, Collembola) in a nearby mofette field. Unlike in nematodes, collembolans and plants, no mofettovageous or mofettophilous spiders were detected. In contrast to humidity, CO2 concentration and temperature, the vegetation cover was not among the factors, which significantly influenced spiders. This is explained by the fact that mofettophilous plants occurred at spots where almost no spiders could live. In a field experiment, most Pardosa pullata males tested passed a 30 cm long corridor with increased carbon dioxide concentration. These results and that of pitfall traps showed that relatively large and wandering specimens respectively were able to transit moderately hostile spots. Further experiments are necessary to find out if there is any active avoidance of high-CO2 areas by spiders. (C) 2016 Elsevier Ltd. All rights reserved.

Assemblages of epigeic spiders were studied in the Dubringer Moor (Saxony, Germany) in 2012 by pitfall-trapping. The Dubringer Moor is a percolation mire that includes (sub-) natural humid habitats such as peat bogs, fens, reeds and birch moor woods. Large areas outside the core zones have been afforested with Pinus sylvestris or Picea abies monocultures. Eight sites were examined: a Sphagnum-rich Erica tetralix-bog (peat bog), a degeneration stage of the bog dominated by Molinia caerulea, four varieties of Picea abies forest and two varieties of birch wood. A total of 130 spider species were collected. A canonical correspondence analysis considering spider occurrence and abundance clearly shows five different groups of species. Their distribution depends on biotic and abiotic environmental factors reflected by habitat type. The results were compared with communities collected at the same peat bog site in 1973 and 1986/1987. The turnover of the most abundant species in each year-Pirata piscatorius in 1973, Piratula hygrophila in 1986/1987 and Aulonia albimana in 2012-illustrates the subtle dehydration that is presumably correlated with heather spreading. We show the actually observed succession and discuss the potential succession based on the 1973, 1986/1987 and 2012 sampling. This study underlines the outstanding indicator value of spiders in peat bogs. This is especially valid for subtle and long-term changes.

Die meisten der mitteleuropäischen Moore sind durch anthropogene Einflüsse, insbesondere durch Trockenlegungen, Torfabbau, Forstund Landwirtschaft stark beeinträchtigt oder zerstört. Durch die Auswirkungen dieser Belastungen gelten die verschiedenen charakteristischen Habitattypen der Moore als bedroht (Succow & Jeschke 1990, Dierßen & Dierßen 2008, Joosten 2012). Die Lebensbedingungen in Mooren mit ihrem niedrigen pH-Wert, Nährstoffarmut und den starken Temperaturschwankungen im Tagesverlauf (Schmidt 1997, Hojdová et al. 2005, Seifert & Pannier 2007, Rydin & Jeglum 2013) stellen für viele Organismen extreme Lebensbedingungen dar, weswegen sich in diesen Habitaten spezifische Lebensgemeinschaften ansiedeln. Mit der akuten Gefährdung von Mooren sind damit auch viele der daran angepassten Pflanzenund Tierarten gefährdet (Scott et al. 2006, Joosten 2012). Aufgrund ihres Artenreichtums und ihrer relativ gut definierten, spezifischen Habitatpräferenzen eignen sich Webspinnen besonders gut zu einer Beurteilung standörtlicher Bedingungen in Mooren (Schikora 2002, Platen 2005, Haase & Balkenhol 2015, Buchholz 2016). Die hier präsentierten Untersuchungen wurden im 1700 ha umfassenden Naturschutzgebiet „Dubringer Moor“ durchgeführt. Dieses DurchströDie Auswirkung der Habitatheterogenität des Dubringer Moores auf die Spinnenfauna (Araneae)

Mofette fields, i.e. geogenic, cold CO2-exhaling gas vents occurring naturally in regions of tectonic or volcanic disturbances provide an excellent opportunity to investigate long-term responses of the soil biota to increased CO2 concentrations. The upper centimeters of mofette soils present a small-scale mosaic of different CO2 and O-2 concentrations: From up to 100% CO2 and 0% O-2 around local degassing vents to ambient soil atmosphere (<2% CO2). The present field study investigated the influence of CO2 on the community structure of Collembola as representatives of the air-filled fraction of the pore system and of Nematoda as inhabitants of soil water films.Canonical correspondence analyses revealed strong correlations between soil faunal communities and environmental measures, above all CO2 concentration, organic matter content and plant coverage. An increase in CO2 concentration was followed by a steady decline in collembolan and nematode species richness and collembolan densities, but below a threshold of 62% CO2 had no significant effect on overall nematode densities. Collembolans developed viable populations at up to 20% CO2, where some mofettophilous species had their highest densities and frequencies, but other more general species also occurred (66% of overall collembolan densities). Nematodes, on the other hand, maintained individual-rich populations at up to 62% CO2, but above 20% CO2 nematode communities consisted almost entirely (97.6%) of three mofettophilous species: one feeding on bacteria, one on fungi and one on plant roots. Likely a combination of active and passive life phases together with temporal and micro-scale changes in environmental conditions allows survival of few mofettophilous species under CO2 conditions too extreme for most other species. The finding that mofettophilous species maintained denser populations in high CO2 patches, with species optima between 3% and 40% CO2, indicates that they even profit from CO2 degassing, presumably via changes in food supply or due to the lack of competitors. (C) 2015 Elsevier Ltd. All rights reserved.