The continued growth of human societies and the 24-hour economy has resulted in overuse of artificial lighting at night. The latter leads to a novel threat to ecosystems which is generally referred to as light pollution. Up to now, it is still unclear how this disruption of the dark phase by artificial light sources affects the reproductive success of aquatic organisms and henceforward, the survival chance of aquatic populations? This can be addressed by concentrating on the link between exposure to different light regimes and reproductive success using the hermaphrodite pond snail Lymnaea stagnalis. In this internship, snails will be experimentally exposed to different controlled light conditions ( periods) during or after which their reproductive output (number and size of eggs) as well as the eggs embryonic development (hatching time and hatchling size) will be observed. In addition, their overall activity in terms of locomotion and speed will be quantified.
This approach can be expanded by exploring whether changes in reproductive output are induced or reduced by the light intensity that they are exposed to and combinations of light periods and intensities. Additionally, their overall mating activity can also be quantified. Taken together, the findings will be important for understanding the possible effects of light pollution on reproduction, locomotion and survival of these organisms.


– Quantifying reproductive output.
– Digital measuring of eggs.
– Determining hatching success.
– Quantifying mating success.
– Digital locomotion activity tracking.

Essential reading:

Hölker, F., Wolter, C., Perkin, E.K., Tockner, K., 2010.
Light pollution as a biodiversity threat. Trends in ecology & evolution 25, 681–682.

Ter Maat, A., Pieneman, A.W., Koene, J.M., 2012.
The effect of light on induced egg laying in the simultaneous hermaphrodite Lymnaea stagnalis. Journal of molluscan studies 78, 262–267.

Ter Maat, A., Zonneveld, C., de Visser, J.A.G., Jansen, R.F., Montagne-Wajer, K., Koene, J.M., 2007.
Food intake, growth, and reproduction as affected by day length and food availability in the pond snail Lymnaea stagnalis. American Malacological Bulletin 23, 113–120.

Health Council of the Netherlands 2000.
Impact of outdoor lighting on man and nature. The Hague: Health Council of the Netherlands, publication no. 2000/25. ISBN 90-5549-349-X


Dr. Joris M. Koene
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