Methods

We have selected five lakes in the Niedere Tauern region that are located at sensitive ecotones and for which, unique in the Alps, datalogger water temperature and chemistry data exist from the survey conducted ten years ago. The water temperature monitoring performed in the years 1998/99 is repeated in order to quantify the decadal temperature variation. Similarly the abundance/distribution of chrysophyte cysts in sediment traps and diatoms, chironomids and cladocera in the sediment surfaces of the lakes will be compared to the situation in the same lakes ten years ago.

The genetic analysis of important planktonic groups will be performed by sequencing ribosomal genes using 454 pyrosequencing, which due to its lower cost per sequence read and high throughput allows for sampling efforts that are orders of magnitude greater than traditional sequencing methods. Typically from cloned sequences a few hundreds to thousand of genotypes can be screened. In contrast using ultra-deep sequencing methods as many as several thousands of DNA sequences of a certain PCR amplified region can be sequenced in parallel leading to the detection of even rarely occurring genotypes.

A seasonal study at the lake Unterer Giglachsee (1921m above SL) will be performed through a high school project (HBLA Ursprung) during summer 2010. Particularly episodic events such as floods or dry periods will be studied by high-frequency (biweekly) or diurnally sampling in order to explore the response of planktonic organisms. Local influences such as snow fields or livestock on the physical and chemical water conditions will receive particular attention. Further the planktonic and benthic organisms occurring in the alpine lakes will be documented and catalogued in order to provide a tool to illustrate the biodiversity occurring in these sensitive ecosystems.