Artificial Light Pollution with Different Wavelengths at Night Interferes with Development, Reproduction, and Antipredator Defenses of Daphnia magna

Artificial light at night (ALAN) dramatically alters the natural daily cycle of light and may cause a suite of physiological and behavioral responses of freshwater crustacean Daphnia. Here, we conducted a life table experiment to investigate the effect of different wavelengths [white (L-L, 400-800 nm), red (R, 614 nm), green (G, 527 nm), and blue (B, 447 nm)] and flashing modes [three colors flash alternately (3-Flash), seven colors strobe alternately (7-Strobe)] of ALAN on the development, reproduction, and predator-induced defenses of Daphnia magna. The results showed that G inhibited the development of the body and tail spine of Daphnia at sexual maturity and decreased their reproduction. The 7-Strobe promoted Daphnia to develop a larger eye. There was an interaction between fish kairomones and ALAN, which intensified over time. ALAN enhanced the response of the relative tail spine length to fish kairomone at sexual maturity. In addition, L-L and R inhibited the body length of 10th instar D. magna in response to fish kairomone. Through the hierarchical cluster method, the 3-Flash and B are recommended as friendly artificial lighting to Daphnia. Our results highlight the interference effects of ALAN on Daphnia, which are helpful to assess the potential impact of light pollution on zooplankton.