Impact of Uv‐b Radiation Upon Estuarine Microcosms

Twelve flow‐through estuarine microcosms were exposed daily to four different levels of UV‐B radiation (290–320. nm)(1.57 ± 102, 6.43 ± 103, 6.86 ± 103 and 7.61 ± 103 J·m‐2d−1) in addition to a natural level of visible solar radiation (380‐800. nm). The parameters studied over a four week period were phytoplankton community composition, plankton biomass (ash‐free dry weight), chlorophyll a concentration and primary productivity (radiocarbon uptake). With increased exposure to UV‐B radiation there was an obvious alteration of the community composition. Daily exposure to enhanced levels of UV‐B radiation also depressed the biomass, the chlorophyll a concentration and the radiocarbon uptake of samples from the ecosystems.