title: Modeling the effects of ultraviolet radiation on estuarine phytoplankton production: impact of variations in exposure and sensitivity to inhibition.
abstract: Spectral ultraviolet (UV) irradiance, water column attenuation and biological weighting functions for inhibition of phytoplankton photosynthesis have been measured for the Rhode River, a subestuary of the Chesapeake Bay. Together, these measurements can be used to estimate UV effects on water column production, but each factor shows a significant range of variability even just considering summer time conditions. A sensitivity analysis of UV inhibition is described which assesses the effect of this variation for different combinations of 28 irradiance spectra, 8 biological weighting functions (BWFs) and 16 water column irradiance profiles. Over all combinations, production averaged about 84% relative to potential production in the absence of UV effects. For a few combinations, relative production was as low as 67%, or as high as 97%, but for most combinations the range was 75-95%. Variations in the sensitivity of the phytoplankton assemblage, i.e. the BWF, and optical properties, represented by a transparency ratio of biologically effective UV to photosynthetically available radiation (PAR), had large effects on water column production. A simple relationship for UV inhibition of water column production is developed based on inhibition at the surface and the ratio of UV and PAR transparency.
authors.affiliation: Smithsonian Environmental Research Center, Edgewater, MD 21037, USA. neale@serc.si.edu
authors.forename: P J
authors.initials: PJ
authors.lastname: Neale
mesh_terms: D000818:Animals; D004307:Dose-Response Relationship, Radiation; D010788:Photosynthesis / Q000528:radiation effects; D010933:Plankton / Q000254:growth & development / Q000528:radiation effects*; D012680:Sensitivity and Specificity; D014466:Ultraviolet Rays; D014867:Water
chemical_list: D014867:Water