Inference of a recent climate driven range expansion in Radix balthica

Data were retained from Swedish national monitoring databases at the Swedish University of Agricultural Sciences SLU. These databases comprise long-term data series from freshwater environments (lakes and rivers) including abundances and biomasses of different organism groups and a variety of environmental parameters. Especially the macrozoobenthos is taxonomically highly resolved and reliable. We used the publicy available monitoring data from 111 Swedish lakes to obtain presence/absence data for Radix specimen. For environmental analysis, 13 data sets of the intensively studied reference lakes, 4 data sets of sites within the largest lakes in Sweden and 5 data sets of rivers were used. The reference lakes have been sampled in different depths and data sets are divided in littoral and sublittoral. All data sets spanned a time of minimally ten years and were sampled once a year, the lakes in late summer/autumn (August to October) after the first mixing, the rivers in spring (May to July) after the snowmelt and the associated flood. The large lakes have the largest data sets beginning with 1969 as the first year included, whereas the sampling of rivers and reference lakes began 1987 and 1988 respectively, 2003 was the last year included. The environmental variables temperature, oxygen, pH, Secchi-depth, conductivity, nutrients (different compounds of nitrogen and phosphorus) and total organic carbon completed the data sets.