The "moon" lighting is believed to affect fish and plants to some extent. Both expect a period of total darkness, and their internal physiological equilibrium can be offset if complete darkness is not provided for a certain period every 24 hours.
I go into this a bit in my brief article on light, here:
We tend to forget than "moonlight" is something very rarely seen by fish living in the tropical regions. The overhanging forest cover creates fairly complete darkness for 10 or so hours.