Penetration and effects of solar UV-B on phytoplankton and macroalgae

The effects of short wavelength solar radiation on aquatic ecosystems were studied in several marine and freshwater systems. The spectral distribution and the penetration of solar radiation into different water types (coastal and oceanic waters of the Baltic Sea, North Sea, Atlantic and Mediterranean) were investigated. Penetration of short wavelength solar radiation strongly depends on the content of dissolved and particulate substances as well as the concentration of phytoplankton. The primary producers often show a typical vertical distribution within the euphotic zone and are reached as well as affected by the penetrating UV-B radiation. The effect of this radiation was both determined in phytoplankton and macroalgae. Measuring pulse amplitude modulated (PAM) fluorescence indicated that major biomass producers were severely inhibited by surface radiation and even impaired at their natural growth site. Likewise, photosynthetic oxygen production was affected by extended exposure to solar radiation.