Artificial light at night represents a ubiquitous anthropogenic disturbance to natural ecosystems. Previous research has determined that the nocturnal drift of aquatic insects is disrupted when artificial light at night is introduced to naturally dark streams. In this experiment, we investigated how exposure to artificial light at night may alter the drift behavior of mayflies from urban (lit) and natural (dark) streams. We hypothesized that the drift of urban mayflies would not be reduced by artificial light, while the drift of mayflies from dark streams would. In order to test this hypothesis, we brought 200 mayflies from four dark and four illuminated streams to the lab, splitting each population into two different flumes, one dimly lit and one dark. Mayflies were left in the flumes overnight and the number remaining in the flumes and those caught in drift nets at the end of the flume were counted.
Results/Conclusions
Mayflies from dark streams drifted significantly less in the lit flume (mean % of mayflies that were in the drift: 0.69 ± 0.05 S.E.) than in the dark flume (0.93 ± 0.03; p = 0.002), while there was no significant difference in the number of drifting mayflies from lit streams between the two treatments (lit: 0.79 ± 0.03; dark: 0.92 ± 0.04; p = 0.1). These results suggest that there may be some local adaptation taking place so that mayflies that have been exposed to artificial light for many generations no longer show as strong of a response to light at night as those in dark streams. Future work should investigate how these shifts in behavior might alter mayfly populations and in-stream predator-prey interactions. This research took place within an interdisciplinary group that also examined different methods of science communication. Therefore, we will also present information about how our group communicated our results and information about artificial light at night to a broad audience.