morning this is when water police tend to come to the surface of the lake to feed on alki biologist hans hoke is waiting for them. to light from a head torches would disturb the experiment so they switch them off only infrared light is allowed. and his team are exploring the effects of sky glow on water. they've positioned l.e.d. lights in circles in a number of test basins they simulate various degrees of light pollution. and. this is explained it's extremely hard to develop a test model which allows you to observe the effects of sky glow on an ecosystem what we have here is a very very diffuse light but it still affects vast swathes of landscape at night. areas. across germany europe all over the world are affected by sky glow the. sky glow and the top. 24 test basins make up a floating laboratory the researchers will be trying to identify the extent that sky glow affects the underwater world the life processes of marine organisms are determined by the intensity of light the researchers take water samples from the test cylinders illuminated to varying degrees samples are taken from various