CS36 Ultraviolet Radiation
Date: Friday, June 14, 2002
Time: 9:30:00 AM
Location: Sidney
 
MoellerR, Lehigh University, Bethlehem, USA, rem3@lehigh.edu
Gilroy, S, , Lehigh University, Bethlehem, USA, slg4@lehigh.edu
Grad, G, , Lehigh University, Bethlehem, USA, gad2@lehigh.edu
Williamson, C, , Lehigh University, Bethlehem, USA, cew0@lehigh.edu
 
DIETARY ACQUISITION OF PHOTOPROTECTIVE COMPOUNDS ENHANCES UV-B TOLERANCE IN PLANKTONIC COPEPODS
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Diaptomid copepods raised on an algal diet rich in mycosporine amino acids (MAA's; from Peridinium) tolerated a standardized 12-hr UV-B exposure better than copepods fed an equally nutritious but non-MAA diet of Cryptomonas. The threshold UV-B intensity causing 50% subsequent mortality (after 5-7 d)was increased 20-60%. The increase occurred both in treatments concurrently exposed to photorepair radiation (PAR,UV-A plus UV-B) as well as in treatments lacking photorepair radiation (UV-B only), which had lower overall tolerance. MAA production in Peridinium --but not Cryptomonas-- was inducible by UV radiation during growth. Copepods accumulated the various dietary MAA's (principal absorbance peaks at 320, 334 and 360 nm) but in proportions different from their food. Fed the same diet, Leptodiaptomus minutus accumulated more MAA's than Skistodiaptomus pallidus. Calanoids collected from especially high UV environments can have several times greater MAA content, suggesting a species-specific capability for MAA accumulation. The suggested role for MAA's in UV photoprotection contributes to the greater UV tolerance of diaptomids compared to Daphnia spp., which lack MAA's.