Altered underwater light characteristics impact photoreceptive mesozooplankton and macrozooplankton from physiological responses to community dynamics

• Impact of underwater light changes on pMMZ explored systematically. • UV radiation causes lethal effects on individual pMMZ. • Behavioral and physiological responses to light intensity and quality examined. • Sub-lethal responses to light variations alter pMMZ traits and community dynamics. • Framework for understanding light-driven pMMZ community changes proposed. Although the underwater light environment is significantly altered by environmental and climatic drivers, a comprehensive review focusing on its effects on photoreceptive mesozooplankton (e.g., rotifers) and macrozooplankton (e.g., cladocerans and copepods), hereafter collectively referred to as pMMZ, has not yet been conducted. Here we summarize current knowledge on the changing light characteristics in global aquatic environments and the effects of those changes on pMMZ traits. Evidence shows that changes in underwater light intensity, quality, and color are evident in present-day natural aquatic ecosystems. Altered light intensity influences pMMZ behaviors, including vertical distribution, feeding behavior, and predator avoidance. Changes in light quality (particularly ultraviolet radiation) can affect pMMZ antioxidant physiology, individual metabolism, gene expression, and development. Thus far, lethal effects on individual pMMZ have only been attributed to elevated ultraviolet radiation under specific conditions. Other changes in light characteristics primarily disrupt pMMZ behavior and physiological traits, indirectly shaping life-history traits and interspecies relationships, which in turn impact community composition and dynamics. In summary, the effects of changes in underwater light characteristics on pMMZ in natural ecosystems are broad-ranging but predominantly indirect. Insights gained from this review shed light on the mechanisms by which changes in underwater light characteristics shape pMMZ communities, underscoring the importance of exploring these effects from a community ecology perspective.