Effects of solar UV radiation (290-400 nm) on the physiology of zooplankton will be investigated within the
framework of this research proposal. It is widely accepted that UV radiation is an important parameter in many
aquatic ecosystems. In zooplankton, which plays a key role in aquatic food webs, many studies have been done to
access potential direct UV effects (e. g., mortality). However, there is a general lack of information on UV-induced
physiological responses in these organisms. The goal of this study, which will be performed at the University of
South Florida, is to address three major questions: i) determine stress proteins in copepods (crustaceans)
synthesized under UV exposure, ii) follow changes in oxygen consumption rates, and iii) estimate UV-induced
changes in metabolic enzyme activities. Monthly sampling (Gulf of Mexico) and in situ UV experiments will give
insight in physiological responses of three prominent copepod species and their different life stages. To measure
qualitative UV responses, copepods will be exposed (~ 10 h) aboard ship in UV-transparent quartz tubes and
respirometers, respectively, to full radiation (i. e., UV-B, UV-A, and PAR [400-700 nm]), UV-A and PAR, PAR
alone and in the dark. Quantitative UV responses will be measured with a gradient of different radiation intensities.
Gelelectrophoresis and western blotting will provide qualitative and quantitative information on the stress proteins
synthesized within the different treatments. Moreover, changes in oxygen consumption rates and UV-induced
metabolic enzyme activities (e. g., citrate synthase) will be determined. In addition to well-known UV-protecting
strategies, like pigmentation, the results of this study will offer new information about fundamental physiological
processes in these organisms.