Have you ever stopped to look at the city lights at night? Have you ever wondered what impact these lights have on wildlife? Chris Thawley, Zach Forsburg, and Krystie Miner all asked this question in their research on artificial light at night, or ALAN.
After exploring how ALAN, affected anoles in a laboratory setting, Thawley, a postdoctoral researcher in Jason Kolbe’s lab at University of Rhode Island, decided to take his experiment into nature. He exposed two species of anole in the Miami area to novel ALAN by installing lights in a botanical garden. Thawley was curious about the broad effects of ALAN on anole behavior, reproduction, and physiology. After exposing anoles to ALAN for two months, Thawley observed that anoles did not change their behavior to avoid the lights. However, anoles in the ALAN treatment had reduced follicle size and larger females produced larger than expected eggs. Thawley also found a reduction in plasma glucose of anoles and hopes to explore the significance of this, in addition to other traits, in the future.
Forsburg and Miner, respective PhD and masters students in the combined lab of Caitlin Gabor and Andrea Aspbury at Texas State University were curious about how ALAN affected an animal’s stress response. Forsburg investigated this in Rio Grande frog tadpoles. He reared tadpoles in the lab under a natural photoperiod and then switched them to either a treatment of constant ALAN or pulses of ALAN for 14 days. Forsburg found that the tadpoles exposed to constant ALAN had increased stress hormone while those exposed to pulses of ALAN has decreased stress hormone. The tadpoles placed under pulses of ALAN did not display a normal stress response when agitated, leading Forsburg to believe pulses of ALAN are more detrimental to the hormonal stress pathway.
Miner asked a similar question in mosquitofish. She exposed females to constant ALAN and measured the response of stress hormone, reproduction, and behavior. In this species, ALAN did not have an affect on stress hormone production or on reproduction. The fish were still able to exhibit a stress response after agitation, so it is not likely that they were chronically stressed. Miner believes that, as an invasive species, mosquitofish might be more tolerant to stressors such as ALAN. While there was no difference in the fish’s hiding behavior under ALAN, those raised under ALAN moved slower and less often.
These studies have certainly illuminated how many diverse responses organisms can have under the stress of the city lights.
- SICB 2019: Artificial Light at Night Has Various Effects on Wildlife - January 5, 2019
- SICB 2019: How Does Road Salt Affect Monarch Butterfly Life History? - January 5, 2019
Leave a Reply