Ultraviolet avoidance by embryonic buoyancy control in three species of marine fish

Pelagic fish embryos are thought to float in or near surface waters for the majority of their development and are presumed to have little to no control over their mobility, rendering these embryos at high risk for damages associated with surface stressors such as ultraviolet radiation (UVR). We recently challenged these long-standing paradigms by characterizing a potential mechanism of stressor avoidance in early-life stage mahi-mahi (Coryphaena hippurus) in which embryos sense external cues, such as UVR, and modify their buoyancy to reduce further exposure. It is unknown whether embryos of other marine fish with pelagic spawning strategies have similar capabilities. To fill this knowledge gap, we investigated buoyancy change in response to UVR in three additional species of marine fish that utilize a pelagic spawning strategy: yellow fin tuna (Thunnus albacares), red snapper (Lutjanus campechanus), and cobia (Rachycentron canadum). Embryos of all three species displayed increased specific gravity and loss of buoyancy after exposures to environmentally relevant doses of UVR, a response that may be ubiquitous to fish with pelagic embryos. To gain further insight into this response, we investigated recovery of buoyancy, oxygen consumption, energy depletion, and photolyase induction in response to UVR exposures in at least one of the three species listed above. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Research has shown that pelagic fish embryos increase their specific gravity and lose buoyancy after exposure to ultraviolet radiation, a response that may be common to all fish with pelagic spawning strategies. Additionally, preliminary results suggest that early-life stage mahi-mahi may reduce further UV exposure by sensing external cues and modifying buoyancy.