Responses of aquatic algae and cyanobacteria to solar UV-B

Continuous depletion of the stratospheric ozone layer has resulted in an in crease in solar ultraviolet-B (UV-B; 280-315 nm) radiation reaching the Ear th's surface. The consequences for aquatic phototrophic organisms of this s mall change in the solar spectrum are currently uncertain. UV radiation has been shown to adversely affect a number of photochemical and photobiologic al processes in a wide variety of aquatic organisms, such as cyanobacteria, phytoplankton and macroalgae. However, a number of photosynthetic organism s counteract the damaging effects of UV-B by synthesizing UV protective com pounds such as mycosporine-like amino acids (MAAs) and the cyanobacterial s heath pigment, scytonemin. The aim of this contribution is to discuss the r esponses of algae and cyanobacteria to solar UV-B radiation and the role of photoprotective compounds in mitigating UV-B damage.