Effect of Sub-Lethal Exposure to Ultraviolet Radiation on the Escape Performance of Atlantic Cod Larvae (Gadus morhua)

Abstract

The amount of ultraviolet (UV) radiation reaching the earth's surface has increased due to depletion of the ozone layer. Several studies have reported that UV radiation reduces survival of fish larvae. However, indirect and sub-lethal impacts of UV radiation on fish behavior have been given little consideration. We observed the escape performance of larval cod (24 dph, SL: 7.6±0.2 mm; 29 dph, SL: 8.2±0.3 mm) that had been exposed to sub-lethal levels of UV radiation vs. unexposed controls. Two predators were used (in separate experiments): two-spotted goby (Gobiusculus flavescens; a suction predator) and lion's mane jellyfish (Cyanea capillata; a “passive" ambush predator). Ten cod larvae were observed in the presence of a predator for 20 minutes using a digital video camera. Trials were replicated 4 times for goby and 5 times for jellyfish. Escape rate (total number of escapes/total number of attacks ×100), escape distance and the number of larvae remaining at the end of the experiment were measured. In the experiment with gobies, in the UV-treated larvae, both escape rate and escape distance (36%, 38±7.5 mm respectively) were significantly lower than those of control larvae (75%, 69±4.7 mm respectively). There was a significant difference in survival as well (UV: 35%, Control: 63%). No apparent escape response was observed, and survival rate was not significantly different, between treatments (UV: 66%, Control: 74%) in the experiment with jellyfish. We conclude that the effect and impact of exposure to sub-lethal levels of UV radiation on the escape performance of cod larvae depends on the type of predator. Our results also suggest that prediction of UV impacts on fish larvae based only on direct effects are underestimations.

Effect of ultraviolet radiation (UVR) on the life stages of fish

“…High variability on UVB tolerance during larval stages have been shown among fish species (Fukunishi et al 2012;Mitchell et al 2008;Sucré et al 2012;Vehniäinen et al 2012). Caspian Sea salmon (Salmo trutta caspius) larvae exposed to 0.5-1.3 W m -2 experienced 100% mortality after 9 days of exposure to UVR (Kazerouni and Khodabandeh 2011).…”

Co‐exposure of ZnO nanoparticles and UV radiation to Daphnia magna and Danio rerio: Combined effects rather than protection

“…This protein has a strong activity during embryogenesis, and it, too, has been linked to the formation of skin tumors in response to UV radiation [36,37]. Ultraviolet radiation also decreases the capacity of fish to escape from predators, as demonstrated for cod larvae by Fukunishi et al [38].…”

Carotenoids in Aquatic Ecosystems and Aquaculture: A Colorful Business with Implications for Human Health

“…Other direct effects of UV exposure on fish eggs or larvae include malformation (Dong et al, 2007), retarded growth (Jokinen et al, 2008), lesion of skin, eyes, and brain (Blazer et al, 1997;McFadzen et al, 2000), and weakened immune system (Markkula et al, 2005, 2006). These pernicious effects may be higher for fish larvae that are often present in surface waters since UV-B (λ = 280-320 nm) exposure induces DNA damage in a variety of fish larvae such as Atlantic cod, northern anchovy Englausis mordax, icefish Cephalus aceratus and Japanese medaka Oryzias latipes (see Fukunishi et al, 2012 for references). UV-B exposure is also likely to weaken fish larvae by inducing physiological stress and damage as suggested by a study that observed a decrease in cod larval escape response to predators, which can increase the impact of predation on fish recruitment success (Fukunishi et al, 2012).…”

“…These pernicious effects may be higher for fish larvae that are often present in surface waters since UV-B (λ = 280-320 nm) exposure induces DNA damage in a variety of fish larvae such as Atlantic cod, northern anchovy Englausis mordax, icefish Cephalus aceratus and Japanese medaka Oryzias latipes (see Fukunishi et al, 2012 for references). UV-B exposure is also likely to weaken fish larvae by inducing physiological stress and damage as suggested by a study that observed a decrease in cod larval escape response to predators, which can increase the impact of predation on fish recruitment success (Fukunishi et al, 2012). The extent of UV induced damage is largely modulated by the presence of competent photoprotection by e.g., carotenoids, mycosporine-like amino acids (MAAs) and other pigments, and photorepair systems.…”