UV-B exposure increases acute toxicity of pentachlorophenol and mercury tothe rotifer Brachionus calyciflorus

Adverse biological effects of ultraviolet-B (UV-B) radiation have been well documented for phytoplankton and zooplankton in both marine and freshwater ecosystems. However, investigations of interactions between UV-B and anthr opogenic toxicants have focused primarily on the chemical interactions betw een UV-B and the toxicant. Here we investigate the potential for UV-B to in crease the sensitivity of the rotifer Brachionus calyciflorus to either acu te pentachlorophenol (PCP) or mercury toxicity, independent of W-B effects on these toxicants. UV-B increased the toxicity of PCP and mercury to B. ca lyciflorus as much as five-fold, depending on duration of UV-B exposure and toxicant concentration. Reductions in the LC50 of up to 60% were also seen for both toxicants. UV-B alone effectively eliminated B. calyciflorus repr oduction and reduced ingestion by up to 90%. These results demonstrate the potential for UV-B to increase rotifer sensitivity to anthropogenic stresso rs independent of photochemical reactions with toxicants. (C) 1999 Elsevier Science Ltd. All rights reserved.