The implications of solar UV radiation exposure for fish and fisheries

Abstract

Ultraviolet radiation (UVR) possesses three important properties that combine to make it a potent environmental force. These include the potential to induce damage: UVR carries more energy per photon than any other wavelength reaching the Earth’s surface. Such highly energetic photons are known to damage many biological molecules, such as DNA and proteins. In addition, they can initiate a series of redox reactions to form reactive oxygen species (ROS), which cause oxidative stress to cells and tissues. The second property is ubiquity: owing to their dependence on light, primary producers and most visual predators, such as fish, are also necessarily exposed to damaging levels of UVR. Thirdly, the combined effect of UVR and additional environmental factors may result in synergistic effects, such as the photoactivation of organic pollutants and photosensitisation. In natural environments, the concentration of dissolved organic matter (DOM) and habitat depth are the two main factors controlling the degree of UVR exposure experienced by fish. Additional factors include vegetation coverage, particulate materials in suspension, pH and hydrological characteristics, and site location (latitude, elevation). The range of potential effects on fish includes direct DNA damage resulting in embryo and larval mortality, and adult and juvenile sunburn, as well as indirect oxidative stress, phototoxicity and photosensitisation.

Environmental influences on larval duration, growth and magnitude of settlement of a coral reef fish

“…Recent work suggests that the early life history stages of fishes and invertebrates are particularly sensitive to the UV radiation present in natural sunlight (Lesser et al 2001;Zagarese and Williamson 2001). The positive correlation between solar radiation and PLD was consistent with the negative relationship between solar radiation and otolith growth up to 25 days, since a longer larval duration is likely to be a consequence of decreased growth.…”

“…Recent work, however, has shown that high levels of light may negatively affect fish larvae. Ultraviolet radiation may induce direct damage to the DNA and proteins of eggs and larvae, causing reduced growth or death (Lesser et al 2001;Zagarese and Williamson 2001). Moreover, Boeuf and Le Bail (1999) suggest that beyond an upper intensity, sunlight may decrease growth and even be deadly due to negative impacts on visual development, which in turn will affect feeding activities and prey selection.…”

“…Similarly, as fish larvae are visual predators, factors such as the amount of solar radiation may either aid feeding by increasing the visibility of prey, or reduce survival by rendering fish more visible to other predators (Fortier et al 1996). Solar radiation may also reduce larval survival through the damaging effect of ultraviolet radiation on nucleic acids or through epidermal damage (Zagarese and Williamson 2001), or indirectly through its impact on secondary production (Kouwenberg et al 1999).…”

Ultraviolet-absorbing compounds in the mucus of shallow-dwelling tropical reef fishes correlate with environmental water clarity

“…Ultraviolet radiation (UV, 280 to 400 nm) is damaging to fishes (Siebeck et al 1994, Lesser et al 2001, Zagarese & Williamson 2001. Shallow-dwelling marine fishes possess UV-absorbing compounds in their mucus, presumably to protect them from harmful UV (Zamzow & Losey 2002, Zamzow 2003, 2004.…”

Visual optics and ecomorphology of the growing shark eye: a comparison between deep and shallow water species

“…The light-filtering properties of the ocular media are attributed to a group of UV-absorbing pigments called mycosporinelike amino acids (MAAs), one of which, asterina-330, has been identified in shark lenses (Dunlap et al, 1989;Douglas and Marshall, 1999). Short-wavelength-filtering ocular media can be advantageous for species inhabiting bright light environments, as UV radiation is damaging to ocular tissue (Walls and Judd, 1933;Dunlap et al, 1989;Douglas and Marshall, 1999;Lesser et al, 2001;Zagarese and Williamson, 2001). However, unless S. mitsukurii undergoes vertical migrations from its deep-water habitat into shallow water, photo-protection from UV light appears an unnecessary adaptation (Frank and Widder, 1996).…”