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Alternate Title

Evidence That Ultraviolet Radiation May Depress Short-Term Photosynthetic Rates of Intertidal Ulva lactuca and Consumption by a Generalist Feeder (Clibanarius vittatus)

Abstract

This article considers the impact of ultraviolet radiation (UVR) on the photosynthesis and consumption of intertidal Ulva lactuca, an important producer and food resource in many coastal ecosystems. Algal fragments were exposed in the laboratory to either UVR and PAR (photosynthetically active radiation) simultaneously or PAR alone. The rates of photosynthesis and consumption by a generalist feeder, the stripped hermit crab (Clibanarius vittatus), were then compared between the two treatments. In both experiments, the biological weighted values for UVR in the laboratory indicate that the experimental set-up provided a level of UVR exposure that would occur in the field. The results show that UVR exposure depresses the photosynthetic rates of U. lactuca at light intensities between 1118 and 2206 μmol m-2 s-1. UVR also reduced the grazing intensity of C. vittatus on U. lactuca with non-UVR-exposed algal pieces supporting about five times more consumption than exposed pieces. The relevance and implications of this study, however, are limited because the results have been obtained with short-term, simple experiments. Studies encompassing a longer time scale and the community of consumers (e.g. exposing both the algae and main consumers simultaneously to experimental UVR levels) are needed to elucidate whether the algae can offset UVR-deleterious effects through the induction of protective compounds and how these compounds and UVR exposure affects the activity of consumers.

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