| This study assessed some of the effects of solar ultraviolet (UV) radiation on coral reef algal assemblages. The first part of the investigation was carried out under controlled laboratory conditions in the coral reef microcosm at the National Museum of Natural History in Washington, D.C., while a field counterpart was completed at the Smithsonian Institution's marine station on Grand Turk, Turks and Caicos Islands, in the eastern Caribbean.; The study attempted to separate the effects of UV-A from those of UV-B. In the laboratory, algal turf assemblages exposed to simulated solar UV radiation (10% of total irradiance) produced 55.1% less biomass than assemblages that were not exposed to UV. Assemblages not exposed to UV were dominated by Ectocarpus rhodochondroides (a brown alga), whereas in the assemblage developing under high UV radiation, Enteromorpha prolifera (a green alga) and eventually Schizothrix calcicola (a blue-green alga) dominated. Lower UV-B irradiances caused a proportional reduction in biomass production and had less pronounced effects on species composition. UV-A did not have any significant effects on either algal turf productivity or community structure. In the field, assemblages exposed to naturally occurring solar UV supported a biomass 40% lower than that of assemblages protected from UV-B exposure. Once again, UV-A did not inhibit algal turf productivity. |
