Project ILES

The project "Illuminating lake ecosystems — ILES" aims at elucidating the ecological consequences of light pollution and the underlying mechanisms. The experiments are performed in the LakeLab, where skyglow is simulated in 10 enclosures using a specially developed light system.


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Nadja Neumann
Public Relations LakeLab
+49 (0)30 64181 975

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ILES – Illuminating Lake Ecosystems

Wednesday, 08.08.2018

Introduction of fish into the LakeLab

5 perch per enclosure explore their new environment

Fish are an important element in the food web of lakes. This also applies to the experimental enclosures of the LakeLab. However, in this case, the number of fish must be controlled so that the results from the individual cylinders can be compared with each other. Because fish from the lake repeatedly jump into the enclosures, all fish must first be removed with nets from the cylinders before starting a new experiment. Today, 5 small perch were released into each enclosure for this year's LakeLab experiment. The LakeLab team got help from Milan Riha and Jan Hlavac, fish experts from the Czech Republic.

At the center of this year's LakeLab experiment is the migratory behavior of zooplankton. While during the day they hide in the darkness of the deep water avoiding to be an easy prey for the fish, at night times they migrate up to the surface water in order to feed on algae. The question is whether the zooplankton adapts its migratory behavior to the altered light regime. Since the vertical migration is triggered not only by the day-night change, but also by chemical messengers, so-called kairomone, which are released by the zooplankton-eating fish, the stocking of the LakeLab enclosures with fish is a prerequisite for the experiment. For this reason, 5 small perch – that corresponds to the population density in Lake Stechlin – were today released into the 20 enclosures participating in the experiment.


Milan Riha (left) and Jan Hlavac (right), two fish experts from the Biology Centre of the Czech Academy of Sciences, have come over from the Bohemian town of Budweis to help with the stocking. It is important to carefully handle the fish, which were weighed and measured before their introduction.


Text and photos: Martina Bauchrowitz, IGB

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