Multifaceted impacts of UVB radiation on morphology, cellular dynamics, and behavior in Macrobrachium olfersii larvae.

The incidence of ultraviolet B (UVB) radiation on Earth's surface has been increasing, impacting marine, coastal, and freshwater organisms. Although these organisms may possess molecular, cellular, and behavioral mechanisms to mitigate the effects of UVB radiation, the embryos and larvae of many species lack fully developed protective strategies. In this context, Macrobrachium olfersii is a decapod essential to the energy cycling of aquatic environments. M. olfersii inhabits shallow and clear coastal waters and is, therefore, susceptible to UVB exposure. This study aimed to investigate the complex effects of UVB radiation on M. olfersii larvae by comparing their responses at two stages of exposure-embryonic and post-hatching-across various levels of cellular, morphological, and behavioral damage. Specifically, we examined whether UVB-induced damage in embryos persists into larval development (first set) and whether irradiated larvae exhibit responses to UVB similar to those observed in irradiated embryos (second set). In the first set of experiments, the parameters of larval body length, eye index, and proteins associated with mitophagy were affected. In the second set, these parameters were impacted, along with more pronounced DNA damage, cell proliferation, and apoptosis. Furthermore, both experimental sets decreased larval migration toward illuminated fields, while cell transparency decreased only in the second set. The results reveal carryover effects of UVB radiation on M. olfersii development, with early exposure prompting adaptation and later exposure causing physiological and functional impairments, potentially reducing predator evasion, survival, and reproductive success.