Potential impacts of floating photovoltaics on carbon fluxes across aquatic-terrestrial boundaries

Floating photovoltaic (FPV) systems are a rapidly expanding renewable energy technology, yet their potential ecological impacts, particularly cross-ecosystem effects, remain poorly understood. This review synthesises current knowledge on organic matter (OM) dynamics and carbon (C) fluxes in lake ecosystems, examining how FPV installations may influence lake C cycling, insect emergence, and greenhouse gas (GHG) emissions. FPV can alter OM availability, shifting the balance between autochthonous and allochthonous inputs. In the short term, installation may increase OM deposition due to the rapid decline of primary producers and riparian vegetation removal. Long-term effects remain uncertain but could drive metabolic regime shifts toward autotrophy or heterotrophy, depending on initial lake conditions. These changes, combined with reduced oxygen and temperature, could significantly alter aquatic food webs, modify GHG fluxes, and alter C dynamics. Increased OM sedimentation could enhance GHG production, while reduced and delayed insect emergence may weaken C transfer to terrestrial ecosystems. Declines in emergent insect biomass could impact terrestrial predators, such as bats and birds, triggering cascading ecological effects. Overall, FPV may reshape carbon fluxes across aquatic–terrestrial boundaries, with impacts varying by FPV coverage and lake-specific factors. There is an urgent need for ecosystem-scale studies and long-term data to assess FPV-induced changes in C fluxes and mitigate its potential impacts on biodiversity and the global C cycle.