Machine derived contents note: Solar Radiation as an Ecosystem Modulator; UVR Climatology; Water Column Optics and Penetration of UVR; Modulation of UVR Exposure and Effects by Vertical Mixing and Advection; Solar UVR and Aquatic Carbon, Nitrogen, Sulfur and Metals Cycles; Photochemistry of Chromophoric Dissolved Organic Matter in Natural Waters; Photoactivated Toxicity in Aquatic Environments; Reactive Oxygen Species in Aquatic Ecosystems; UVR-Induced DNA Damage in Aquatic Organisms; Photoprotective Physiological and Biochemical Responses of Aquatic Organisms to UVR; Photosynthesis in the Aquatic Environment as Affected by UVR; Subject Index