The Eendragtspolder in Zevenhuizen was flooded this summer for a large-scale experiment. More than ten Dutch research institutes, led by the Pandemic and Disaster Preparedness Center, investigated how water storage affects wildlife and public health. The Pandemic and Disaster Preparedness Center is a partnership between Erasmus MC, Erasmus University Rotterdam and TU Delft.
Researchers moved into the area to study animals. Salamanders, moles and mice looked for a drier place when the polder was flooded. Mosquitoes, other insects and birds such as crows, pigeons, waders and the purple coot were attracted to it. Mosquitoes lay their eggs in stagnant water. The scientists therefore wanted to know whether flooding the polder would lead to a large increase in the number of mosquitoes and which mosquito species find such a flooded polder attractive.
Various traps were used to search for mosquitoes and blood-sucking insects. In addition, researchers from Erasmus MC also took water samples for virus and DNA analysis. With eDNA, scientists can use one sample to identify multiple species that occur in an area. The experiment has made it clear how different animals react to a flood, and that a flooded polder can indeed breed many mosquitoes in the summer. The researchers are now looking at adjustments in the design of water storage facilities that can ensure that these water buffers pose the smallest possible risk to public health.
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