Hur påverkade den torra sommaren 2018 bottenfaunans artdiversitet, individtäthet och den ekologiska statusen i vattendrag i södra Sverige?

Sammanfattning: During the summer of 2018 Northern Europe, including Sweden, was affected by extremely high temperature and drought. The drought affected the society and environment that we and other organisms live in. Streams are one of the ecosystems sensible to these conditions. Long periods of drought may affect the waterflow or cause desiccation of streams. Since streams provide important ecological services, they are equally important to humans as to organisms living in them. In this study I investigate whether the dry summer of 2018 had any effect on the species diversity, density of individuals and ecological status in 16 randomly chosen southern Swedish streams. This was done by comparing number of species, average number of individuals per sample, ASPT- and MISA-indices in 2018 with reference years 2007–2017. In addition to this, I investigated whether the independent variables geographical location, pH and alkalinity had any effect on the deviation of 2018 compared to the reference years. The results showed that there were no significant differences between 2018 and the reference years for any of the variables. Thus, the dry summer of 2018 had no general effect. However, the southernmost streams generally generated negative deviations, while northern generally generated positive ones for average number of individuals per sample. To further understand how drought affects benthic invertebrates in streams that are not fully dried out further research should be conducted to examine how the composition of species is affected.