Publication details
Mollusc assemblages in fens of southern Scandinavia: variation along the gradient of mineral richness
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| Year of publication | 2010 |
| Type | Appeared in Conference without Proceedings |
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| Description | Spring fens are ecologically specific biotopes, which can harbour diverse mollusc assemblages. Species composition and diversity of fen mollusc faunas are driven especially by the gradient of mineral richness (i.e. changes of ground water chemical parameters, mainly calcium and magnesium), that accounts for sharp changes of fen biota from mineral-poor (acidic) to mineral-rich (calcareous) fens. As the calcium content appears to be a limiting factor for molluscs in fens, species richness and abundances usually tightly increase with increasing mineral richness in spring fens. The mollusc fauna changes along the mineral richness gradient of spring fens were studied in detail in the Western Carpathians and Bulgaria. In this contribution we present new results from fens in southern Scandinavia. The field work was conducted in August 2006 within the territory of southern Norway and Sweden. Altogether 43 fen sites were sampled in order to cover the entire ecological variation of fens, especially in respect of the mineral richness gradient. Water conductivity and pH, geographic coordinates and altitude were measured in the field. Vegetation relevé was recorded at each site and climatic parameters (mean temperatures and precipitations) were compiled for each site. The data were processed using Statistica, PC-ORD and CANOCO packages. A total of 45 mollusc species were found in the studied fens. Mollusc assemblages consisted of typical northern cold-climate species (e.g. Vertigo genesii, Columella columella, Vertigo arctica and Vertigo lilljeborgi) as well as common Central European species (e.g. Cochlicopa lubrica and Perpolita hammonis). Both number of species and individuals increased with increasing mineral richness, and water conductivity explained these changes better than water pH. Species densities and abundances of terrestrial snails were more tightly associated with the mineral richness than those for the entire assemblages. The major gradient in mollusc data was controlled by the mineral richness, the second one was associated with the climate variation, strongly correlated with altitude. The main direction of mollusc species turnover was associated with that observed for vegetation and plant species composition was found to be the best predictor of overall variation in mollusc data. |
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