Tardigrade species composition in young soils and some aspects on life history of Macrobiotus richtersi J. Murray, 1911

In an afforested coal-mining site at Berzdorf, Germany, the soil tardigrade community was investigated. Tardigrade densities ranged from 300 to 33,600 individuals m(-2). Tardigrade distribution was very aggregated with standard deviations of up to 220% of mean densities. Fourteen species belonging to five eutardigrade genera were identified. Soils were dominated by the carnivorous tardigrade Macrobiotus richtersi that contributed 60% of overall densities. A comparison between nine soils of different forest ages (4-46 years) and tree species (poplar, alder, pine, mixed deciduous and mixed coniferous) showed no relationship of tardigrade species distribution and abundance to tree species, thickness of organic or litter layer, humus form, pH or soil moisture. Further, no correlation between nematode biomass and Macrobiotus richtersi abundances were detected. The age of afforested soils, however, affected tardigrade densities: younger soils (7-17 years) yielded higher tardigrade numbers compared to 46-year-old sites. Life history investigations on a strain of parthenogenetic Macrobiotus richtersi demonstrated a significant influence of temperature on egg development, survival rate, body growth and generation time. Hatching, first to fourth molts and maturing, on the other hand, were dependent upon body size alone. The simple, new culture method for carnivorous tardigrades described has successfutly been utilized for parthenogenetic Mocrobiotus richtersi for 6 years. (c) 2006 Elsevier GmbH. All rights reserved.