Ecological responses of aquatic invertebrates to climate change over the past ∼400 years in a climatically ultra-sensitive lake in the Niedere Tauern Alps (Austria)

A sediment core covering the past similar to 400 years from Lake Moaralmsee (central Austrian Alps), which has previously been judged to be ultra-sensitive to climate change due to its unusually cold water, was examined for its fossil invertebrates. The aim of this study was to investigate whether the faunal assemblages had experienced changes in their composition during periods of the Little Ice Age and recent climate warming. Although there was some general lag between the community changes of these animal groups, the faunal dynamics showed significant correlation between the principal component axes. A mutual break point in the assemblages occurred in the beginning of the 20th century corresponding to increased global and Alpine air temperatures. A gradual decrease in diversity was detected for chironomids, but the only major change in the diversity of Cladocera occurred between similar to 1900 and 1950AD when it was markedly lower. The results indicate that Lake Moaralmsee has gone through clear changes in its invertebrate fauna during the past centuries that were most likely related to climate warming, with the most dramatic changes occurring almost a century ago.