Biological weighting function for the mortality of Boeckella gracilipes (Copepoda, Crustacea) derived from experiments with natural solar radiation

We performed in situ experiments during the austral summer of 1998 to quantify the mortality of the fresh-water copepod Boeckella gracilipes as a function of the UV dose. The copepods were exposed to solar radiation at the water-surface for approximately 24-34 h. Long-pass cut-off filters (Schott) were used in the exposure experiments. UV radiation and PAR were measured with an IL-1700 (International Light Inc.) and a PUV-500 radiometer (Biospherical Instruments Inc.). A biological weighting function for UV-induced mortality was calculated by fitting a model based on a logistic curve. Our results show that UV damage in this species is strongly wavelength- and dose-dependent. B. gracilipes was highly vulnerable to both UV-B (290-320 nm) and UV-A radiation (< 360 nm). The shape of the BWF obtained for B. gracilipes resembles more closely the action spectra (AS) for UV-induced erythema, than the AS for naked DNA.