A Meta‐Analysis of the Effects of Ultraviolet B Radiation and Its Synergistic Interactions with pH, Contaminants, and Disease on Amphibian Survival

Abstract

Human alterations to natural systems have resulted in a loss of biological diversity around the world. Amphibian population losses have been more severe than those of birds and mammals. Amphibian population declines are likely due to many factors including habitat loss, disease, contaminants, introduced species and ultraviolet-B (UVB) radiation. The effect of UVB, however, varies widely among species and can vary within populations of the same species or at different life-history stages. This variation has often led to opposing conclusions about how UVB affects amphibians. We used meta-analysis techniques to explore the overall effects of UVB radiation on survival in amphibians. We also used recently developed factorial meta-analytic techniques to quantify potential interactions between UVB radiation and other stressors on amphibians. Ultraviolet-B radiation reduced survival of amphibians by 1.9-fold compared with shielded controls. Larvae were more susceptible to damage from UVB radiation compared with embryos, and salamanders were more susceptible compared with frogs and toads. Furthermore, UVB radiation interacted synergistically with other environmental stressors and resulted in greater than additive effects on survival when 2 stressors were present. Our results suggest that UVB radiation is an important stressor in amphibians, particularly in light of potential synergisms between UVB and other stressors in amphibian habitats.

Climate change and pollution speed declines in zebrafish populations

“…Examples include interactions between temperature and metals impairing development of individual zebrafish (5); temperature and pesticides affecting physiological and sexual development in fish (6) and in reptiles (10); and UV-B radiation in combination with various other physical, chemical, or biological stressors having an impact on individual amphibian survival (8). However, there have been very few studies of population-level impacts due to interactions between chemicals and other environmental stressors (4,11,12).…”

“…Combinations of environmental stressors have been shown to have interactive effects on the health of individuals in many taxa (4), including fish (5,6), amphibians (7,8), and reptiles (9,10), with indications of interactive effects at the population level for some invertebrates (11,12). It is also recognized that small, isolated, and inbred wildlife populations are potentially more vulnerable to environmental change because of their lower adaptive capabilities (13,14).…”

A small increase in UV-B increases the susceptibility of tadpoles to predation

“…[19]). Nevertheless, a recent quantitative meta-analysis of 89 studies of the effects of ambient UV-B on embryonic and larval survival demonstrated that, on average, UV-B exposure reduced survival by nearly half [20]. Such a finding indicates that UV-B is indeed an important stressor in amphibian habitats, but, as Croteau et al [7] point out in their review, 'we must move beyond solely examining overt death of amphibians and begin to understand [the] subtle effects of [UV-B] alone and in combination with other stressors' (p. 757).…”

Synergistic interaction between UVB radiation and temperature increases susceptibility to parasitic infection in a fish

“…The impact of UVB can be exacerbated by interactions with other environmental drivers [3,6,[10][11][12]. Temperature, in particular, can modulate the effects of UVB; for example, simultaneous exposure of amphibian embryos to low temperatures and high UV radiation levels caused a synergistic increase in mortality [6].…”

“…The potential of such an interaction is of particular concern in the context of climate warming [1,2]. High UVB can impair the immune system [9,10], and high temperature can increase pathogen loads [13]. Many vertebrate species are constrained by pathogen loads [14], and a synergistic interaction between UVB and increasing temperatures on disease resistance could have important consequences.…”