This week, lakes in the Trondheim city forest are treated with rotenone to remove common roach (Rutilus rutilus). We know that all fish will be killed by rotenone, but previous studies indicate that macroinvertebrates in lakes are less affected than previously thought (Arnekleiv et al. 2015). In EBAI we will use eDNA and DNA barcoding of bulk macroinvertebrate samples to see how molecular tools can be used to monitor changes in the invertebrate communities after rotenone treatment. Will we detect a change in the invertebrate community? How long will it take until changes are detected as eDNA in water samples? Time will show.

treating-kyvannet-with-rotenoneBoats are used to distribute the rotenone evenly throughout the lake Kyvatnet. Photo: Torbjørn Ekrem cc-by.

Several lakes in the Trondheim city forest will soon be treated with rotenone to remove the common roach (Rutilus rutilus), an invasive alien species in our area. Together with freshwater ecologists at the NTNU University Museum, we are interested to see how the macroinvertebrates react to the treatment and if we can use eDNA to monitor changes and shifts in the species compositions.

Yesteday, we sampled three of the lakes that will undergo treatment as well as three reference lakes. We have three sampling stations at each lake and filter 2 x 1 liter of water from each station. This video shows how samples are taken.

Weather was great and fieldwork successful.

lauglovatnet Gaute Kjærstad sampling water at the lake Lauglovatnet. Photo Torbjørn Ekrem CC-BY.

theisendammenTwo water samples from the lake Theisendammen. Photo Torbjørn Ekrem CC-BY.