Banaszak, A. T.. Smithsonian Environmental Research Center, banaszak@serc.si.edu
Neale, P. T.. Smithsonian Environmental Research Center, neale@serc.si.edu
Miller, H. L.. University of Texas, miller@utmsi.utmsi.utexas.edu
Dunton, K. H.. University of Texas, dunton@utmsi.utmsi.utexas.edu

 
RESPONSE OF TWO SPECIES OF ARCTIC KELP TO ULTRAVIOLET RADIATION (UVR): PHOTOINHIBITION AND RECOVERY
 
Response of Laminaria saccharina and L. solidungula to ambient UV was assessed using carbon uptake rates and photosynthetic efficiency parameters (Fv:Fm). Carbon uptake rates were assayed in blades incubated in UV-opaque (UVO) and UV-transparent (UVT) tanks containing 13C-enriched seawater over 5, 18 and 22 hour exposures. Four time courses were conducted with five replicates for each species in tanks shaded to simulate their uppermost depth distribution. During the same incubations, Fv:Fm was measured after 5, 9, 18 and 22 hour exposures using Pulse Amplitude Modulated (PAM) fluorescence. One UV-exposed blade was monitored continuously to resolve inhibition and recovery rates during each incubation. Photosynthesis in both species was sensitive to UV inhibition as measured by carbon uptake and Fv:Fm values. Carbon uptake rates suggest that L. saccharina is more sensitive than L. solidungula during UV exposure whereas Fv:Fm values suggest that L. solidungula is the more sensitive species. Rates of post-exposure recovery are slower in both species than are rates of UV inhibition and L. solidungula is slower to recover than L. saccharina. Time courses of carbon uptake and Fv:Fm suggest that recovery after UV inhibition is slow thereby increasing the impact of UV on daily photosynthesis particularly for L. solidungula.
 
Day: Wednesday, Feb. 3
Time: 10:30 - 10:45am
Location: Sweeney Center
 
Code: CS65WE1030S