The effect of intensified illuminance and artificial light at night on fitness and susceptibility to abiotic and biotic stressors. (August 2019)

• Record Type: Journal Article
• Authors: May, Dyllan; Shidemantle, Grascen; Melnick-Kelley, Quentin; Crane, Kelly; Hua, Jessica
• Is Part Of: Environmental pollution. Volume 251(2019)
• Page Start: 600
• Page End: 608
• Publication Date: 2019-08
• Subjects: Artificial light at night -- Amphibian -- Host-parasite -- Light pollution -- Road salt; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2019.05.016
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Changing light conditions due to human activities represents an important emerging environmental concern. Although changes to natural light conditions can be independently detrimental, in nature, organisms commonly face multiple stressors. To understand the consequences of altered light conditions, we exposed a model amphibian (wood frog; Lithobates sylvaticus ) to a control and two anthropogenic light conditions: intensified daytime illuminance and artificial light at night - ALAN (intensified daytime illuminance + extended photoperiod). We measured (1) metrics of fitness (hatching success as well as survival to, size at, and time to metamorphosis) (2) susceptibility (time to death) to a commonly co-occurring anthropogenic stressor, road salt (NaCl) and (3) susceptibility (infection load) to a common parasite (trematode). We also explored behavioral (swimming activity) and physiological (baseline corticosterone (CORT) release rates) changes induced by these light conditions, which may mediate changes in the other measured parameters. We found that both intensified daytime illuminance and ALAN reduced hatching success. In contrast, for amphibians that successfully hatched, neither treatment affected amphibian survival or time to metamorphosis but individuals exposed to ALAN were larger at metamorphosis. The light treatments also had marginal effects; individuals in ALAN treatments were more susceptible to NaCl and trematodes. Finally, tadpoles exposed to ALAN moved significantly less than tadpoles in the control and intensified daytime illuminance treatments, while light had no effect on CORT release rate. Overall, changes in light conditions, in particular ALAN, significantly impacted an amphibian model in laboratory conditions. This work underscores the importance of considering not only the direct effects of light on fitness metrics but also the indirect effects of light with other abiotic and biotic stressors. Anthropogenic-induced changes to light conditions are expected to continue increasing over time so understanding the diverse consequences of shifting light conditions will be paramount to protecting wildlife populations. Graphical abstract: Image 1 Highlights: Exposure to light pollution reduced hatching success of wood frog embryos. Wood frogs exposed to ALAN were significantly larger at metamorphosis. Wood frog tadpoles exposed to ALAN were marginally more susceptible to road salt (NaCl). Wood frog tadpoles exposed to ALAN were marginally more susceptible to parasite infection. Wood frogs exposed to ALAN had reduced swimming activity but CORT levels were unaffected. Abstract : Light pollution reduced hatching in wood frog embryos. Tadpoles exposed to ALAN were significantly larger, more susceptible to NaCl and parasites, and less active.