CEDREN nyheter

Searching for benthos

Published on: 4. November 2010

While many biologists sit down at their warm lab or office in the colder season, EnviPEAK researchers start their high season. - Colder weather means that rivers get more exposed to hydropeaking. We need to sample in this period to answer how hydropeaking influence the benthic fauna, says research scientist Zlatko Petrin.

Searching for benthos
Research scientist Zlatko Petrin almost ready for river field work. Photo © O. Rønning/CEDREN



The EnviPEAK Invertebrate Specialist Group started sampling benthic macroinvertebrates around Trondheim in October. Benthic samples and the agreed additional measurements have been taken at Lundesokna and Stjørdal. – We will continue sampling at Surna in November followed by the other sites at a later stage, says Petrin, research scientist at Norwegian Institute for Nature Research (NINA).


The invertebrate specialist group is conducting field work for the CEDREN project EnviPEAK. The main objective of EnviPEAK is to develop knowledge and tools to analyse, predict and mitigate environmental impacts from rapid and frequent changes in hydropower production regimes (hydropeaking).


See hydropeaking video from Lundesokna river in central Norway. An upstream
power plant rapidly releases more water in the river © SINTEF/CEDREN:



Further benthos field work

The power station at Vallaråi has been running continuously for one month and will likely continue to do so next month. Hence, the draw down zone has been permanently inundated for one month, and the effect from hydropeaking operation has likely disappeared. In addition, sampling the main channel is impossible at present due to the high flow. Sampling Vallaråi has therefore been postponed to the end of November, possibly December, or if necessary later.

At Daleelva, water availability for the power station is high. The power station therefore runs continuously. However, hydropeaking operation has been employed during previous week’s cold weather spell. We may hence get hydropeaking operation again when it gets colder. The field team may therefore decide to postpone sampling until later in November depending on the weather conditions. At present, the hydropeaking effect is likely weak.

PhD Research Scholar Tania Zakowski (NINA) has initiated the decomposition experiment at Lundesokna and Stjørdal. However, due to logistic challenges and the nearing winter, we have decided to postpone running the full scale decomposition experiment until next spring. Hence, the experiment at Lundesokna and Stjørdal will serve as pilot study. For next year, sufficient raw material will be available, and the preparations are largely complete. From a scientific point of view, we do not see major problems with postponing the experiment, as detritus is available year round, although detritus availability peaks in the autumn. Due to detritus limitations in spring, we expect high decomposition rates and therefore larger effect sizes during spring than autumn. Decomposition experiments were successfully performed during spring in previous studies.

Sediment samples have also been collected: At Surna, freeze core samples have been collected and will continue to be collected next week. At the end of next week, sampling will also commence at the camping site at Lundesokna.

Two data loggers recording water temperature each minute have been installed at Daleelva: one upstream and the other downstream from the outlet of the power station. Another data logger has been installed downstream recording water levels at one-minute intervals. Upstream, water levels are recorded by NVE each hour.



Contact persons:

Atle Harby for CEDREN and EnviPEAK
Zlatko Petrin for the EnviPEAK specialist group