Deitsch, J. F. | Search bioRxiv

bioRxiv2026

Organismal responses to artificial light at night in terrestrial ecosystems vary across lunar cycles

Globally, nocturnal lightscapes are now determined by both moonlight and light pollution, or artificial light at night (ALAN). Organisms respond both to changes in moonlight across lunar cycles and to alterations in light conditions due to artificial light. The interaction of natural and artificial light is a critical aspect to incorporate into our understanding of how crepuscular and nocturnal ecology is altered in anthropogenically-modified landscapes. In this manuscript we review the rapidly expanding body of research on ecological impacts of ALAN to (1) assess patterns of lunar data inclusion and (2) summarize documented interactions of moonlight and ALAN. Three-fourths (72%) of 379 papers reviewed did not incorporate moonlight into their statistical analyses and experimental design. Only 12% directly investigated interaction effects of moonlight and ALAN. However, 70% of these studies reported an interactive effect. Considering this stark contrast, as a precursor to our literature review, we present an overview of moonlight and the lunar cycle for biologists. The overarching trend emerging from the literature is that biological impacts of ALAN decrease with increasing moonlight, although the opposite is true in some cases. After summarizing the literature, we present general hypotheses regarding the interaction of the lunar cycle and ALAN. These hypotheses consider the different forms of ALAN encountered by organisms (i.e. skyglow and light sources) and account for the influence of cloud cover. Finally, we suggest best practices for incorporating moonlight into future research on biological impacts of ALAN.

ecology↗

bioRxiv2023

Veni, vidi, vici? Future spread and ecological impacts of a rapidly-expanding invasive predator population

Economic and ecological consequences of invasive species make biological invasions an influential driver of global change. Monitoring the spread and impacts of non-native species is essential, but often difficult, especially during the initial stages of invasion. The Joro spider, Trichonephila clavata (L. Koch, 1878, Araneae: Araneidae), is a large-bodied orb weaver native to Asia, likely introduced to northern Georgia, U.S. around 2010. We investigated the nascent invasion of T. clavata by constructing species distribution models (SDMs) from crowdsourced data to compare the climate T. clavata experiences in its native range to its introduced range. We found evidence that the climate of T. clavatas native range differs significantly from its introduced range and that the most similar climate in North America to its native range is to the north of its current introduced range. We then compared the SDM predictions to current observations of spread. Consistent with predictions, T. clavata appears to be spreading faster to the north than to the south. Lastly, we conducted surveys to investigate potential ecological impacts of T. clavata on the diversity of native orb weaving spiders. Importantly, Trichonephila clavata was the most common and abundant species observed in the survey, and was numerically dominant at half of the sites it was present in. Our models also suggest that there is lower native orb weaver species richness and diversity closer to where T. clavata was initially found and where it has been established the longest, though human population density complicates this finding. This early study is the first to forecast how widely this spider may spread in its introduced range and explore potential ecological impacts of T. clavata, and we call for continued investigation of this invasions effects.

ecology↗