While the majority of research on ultraviolet radiation (UVR) has focused on UVR-induced changes in the productivity and abundance of single taxonomic groups, only a few field studies have considered the influence of ambient UVR on complete assemblages, in particular of the macrobenthos. Using cutoff filters, we followed the effects of three radiation treatments, (1) PAR+UVAR+UVBR, (2) PAR+UVAR, (3) PAR, on macrobenthic community structure at Lüderitz, Namibia, SE Atlantic, for 3 months.
Species composition, biomass, evenness, and species richness were not significantly affected by UVR, while the diversity H′ of PAR+UVAR+UVBR-exposed communities was significantly lower compared to PAR treatments. However, this effect was only observed early in succession. Increased abundance of the red alga Ceramium sp. coincided with vanishing UVR effects on the community, suggesting a muted UVR microclimate under the Ceramium canopy.
Our results demonstrate that UVR could neither decrease diversity persistently, nor affect any of the other tested community parameters. Single UVR-tolerant species may provide protective shading for UVR-sensitive species, thus buffering harmful UVR effects at the community level. Missing UVBR effects suggest a limited influence of ozone depletion on shallow water macrobenthic diversity.
Molis, M. and Wahl, M., 2004. Transient effects of solar ultraviolet radiation on the diversity and structure of a field-grown epibenthic community at Lüderitz, Namibia. Journal of Experimental Marine Biology and Ecology, 302(1), pp.51-62.
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