Sublethal consequences of ultraviolet radiation exposure on vertebrates: Synthesis through meta‐analysis

Abstract

Ultraviolet radiation (UVR) from the sun is a natural daytime stressor for vertebrates in both terrestrial and aquatic ecosystems. UVR effects on the physiology of vertebrates manifest at the cellular level, but have bottom‐up effects at the tissue level and on whole‐animal performance and behaviours. Climate change and habitat loss (i.e. loss of shelter from UVR) could interact with and exacerbate the genotoxic and cytotoxic impacts of UVR on vertebrates. Therefore, it is important to understand the range and magnitude of effects that UVR can have on a diversity of physiological metrics, and how these may be shaped by taxa, life stage or geographical range in the major vertebrate groups. Using a meta‐analytical approach, we used 895 observations from 47 different vertebrate species (fish, amphibian, reptile and bird), and 51 physiological metrics (i.e. cellular, tissue and whole‐animal metrics), across 73 independent studies, to elucidate the general patterns of UVR effects on vertebrate physiology. We found that while UVR's impacts on vertebrates are generally negative, fish and amphibians were the most susceptible taxa, adult and larvae were the most susceptible life stages, and animals inhabiting temperate and tropical latitudes were the most susceptible to UVR stress. This information is critical to further our understanding of the adaptive capacity of vulnerable taxon to UVR stress, and the wide‐spread sublethal physiological effects of UVR on vertebrates, such as DNA damage and cellular stress, which may translate up to impaired growth and locomotor performance. These impairments to individual fitness highlighted by our study may potentially cause disruptions at the ecosystem scale, especially if the effects of this pervasive diurnal stressor are exacerbated by climate change and reduced refuge due to habitat loss and degradation. Therefore, conservation of habitats that provide refuge to UVR stress will be critical to mitigate stress from this pervasive daytime stressor.

Extended ozone depletion and reduced snow and ice cover—Consequences for Antarctic biota

“…The extent of any UV‐B damage to these Antarctic organisms will depend on susceptibility, the level of UV defense that organisms possess as well as the cost of production of any additional defense and repair mechanisms (Karentz & Bosch, 2001). Birds and mammals have outer coverings of fur and feathers that reflect UV radiation or act as a barrier, rendering these animals more resistant than other vertebrate groups such as fish, which lack such physical protection (Downie et al., 2023; Jin, 2023). Animals also rely on melanin to protect their bodies.…”

“…The level of UV photoprotection can also vary with the life cycle stage. Vertebrate vulnerability to UV‐B radiation is dependent on taxa, life stage and latitude (Downie et al., 2023; Jin, 2023; Karentz & Bosch, 2001). Adults and larvae of fish species are more susceptible to UV radiation, whereas embryos are often less affected (Downie et al., 2023).…”

“…Vertebrate vulnerability to UV‐B radiation is dependent on taxa, life stage and latitude (Downie et al., 2023; Jin, 2023; Karentz & Bosch, 2001). Adults and larvae of fish species are more susceptible to UV radiation, whereas embryos are often less affected (Downie et al., 2023). Two factors have been suggested to explain the higher tolerance to UV radiation of fish eggs (Downie et al., 2023).…”

Vertebrates under ultraviolet radiation

“…Downie et al (2023) also show that the vulnerability of vertebrates to UVR is life‐stage dependent. They demonstrate that adults and larvae are the most susceptible life stages, while the effect of UVR on embryos or juveniles was found to be not significant.…”

“…In their meta‐analysis paper in this issue of Global Change Biology, Downie et al (2023) conducted a comprehensive and in‐depth analysis using 895 observations from 47 different vertebrate species (fish, amphibians, reptiles and birds) and 51 physiological metrics (i.e. cellular, tissue and whole‐animal metrics), across 73 independent studies, to examine the response patterns of UVR effects on vertebrate physiology.…”