Impact of temperature on UV-susceptibility of two Ulva (Chlorophyta) species from Antarctic and Subantarctic regions

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1 of two Ulva (Chlorophyta) species from Antarctic and Subantarctic regions Institute for Polar Ecology Ralf Rautenberger Christian Albrechts University of Kiel Institute for Polar Ecology Christian Albrechts University of Kiel (Germany)

2 The Antarctic ozone hole Establishment in austral spring every year In 2 and 23: 28 million km 2 Extended to South America: 45 S in an increase of UV-Bradiation on earth s surface Increased UVB-radiation affects macroalgae as an important ecological component

3 Water temperatures poet.jpl.nasa.gov Controlling macroalgal growth, distribution and stress Potential changes of water temperatures in Antarctica affect marine life, e.g. macroalgae

clathrata M.D. Guiry Drake Passage Jubany Base Antarctic Peninsula Map: www.aquarius.geomar.

4 Algal material 75 W 7 Argentina 65 Falkland Islands 6 55 W 5 S Puerto Williams: Ulva clathrata cosmopolitan/cold-temperate species Chile Puerto Williams 55 cold-temperate waters: 5-1 C Ulva clathrata M.D. Guiry Drake Passage Jubany Base Antarctic Peninsula Map: 65 S 6 Jubany Base: Ulva bulbosa Antarctic/cold-temperate species: -2-2 C Tide pools: >> 2 C Ulva bulbosa R. Rautenberger

5 of the study UV-radiation 4 days of cultivation Temperature PAR = 1 μmol photons m -2 s -1 UVA = 4.1 W m -2 1 = C UVB =.7 W m -2 2 = 1 C Photosynthesis Oxidative stress Interactive effects of UV-radiation and temperature on the physiological and ecological level

6 Photosynthesis of U. bulbosa C 1 C Fv/Fm (r.u.) PAR PAR+UVA PAR+UVA+UVB Time of UV-exposure (days) UV-induced inhibition of photosynthesis compensation of UV-induced photoinhibition by increased temperature

7 Photosynthesis of U. clathrata C 1 C Fv/Fm (r.u.) PAR PAR+UVA PAR+UVA+UVB Time of UV-exposure (days) UV-induced inhibition of photosynthesis was much more pronounced compensation of UV-induced photoinhibition by increased temperature

8 Activities of superoxide dismutase in U. bulbosa C 1 C SOD activity (Units mg -1 protein) PAR PAR+UVA PAR+UVA+UVB Time of UV-exposure (days) No significant differences between light and temperature treatments!

9 Activities of superoxide dismutase in U. clathrata C 1 C SOD activity (Units mg -1 protein) PAR PAR+UVA PAR+UVA+UVB Time of UV-exposure (days) No significant differences between light treatments!

10 Content of malondialdehyde in U. bulbosa C 1 C MDA content (μmol mg -1 fw) PAR PAR+UVA PAR+UVA+UVB Time of UV-exposure (days) No significant differences between light treatments!

11 Content of malondialdehyde in U. clathrata C 1 C MDA content (μmol mg -1 fw) PAR PAR+UVA PAR+UVA+UVB 4 4 Time of UV-exposure (days) No significant differences between light treatments!

12 Physiological interpretation UV-radiation induced inhibition of photosynthesis at C but did not cause any oxidative stress Compensation of UV-induced photoinhibition by increased temperature, probably due to increased activities of key enzymes involved in photoprotection Higher SOD activities in U. bulbosa than in U. clathrata suggest a more efficient management of oxidative stress at permanent low temperatures

13 Ecological Interpretation U. bulbosa seems better adapted to cope with UVradiation than U. clathrata at lower temperatures U. bulbosa in the eulittoral is affected by UV-radiation but photoinhibition is reversible In tide pools, increased temperatures may diminish UVeffects in U. bulbosa U. clathrata from South America does not experience similarly low temperatures K. v. Juterzenka There, higher water temperatures facilitate a higher activity of physiological protection mechanisms

14 Thank you for your attention. Institute for Polar Ecology Christian Albrechts University of Kiel Rautenberger R and Bischof K (26) of two Ulva (Chlorophyta) species from Antarctic and Subantarctic regions. Polar Biology (Online First)

Elizabeth Beauchamp. Project advisor: Maria Donkin, School of Biomedical and Biological Sciences, Plymouth University, Drake Circus, Plymouth

Elizabeth Beauchamp. Project advisor: Maria Donkin, School of Biomedical and Biological Sciences, Plymouth University, Drake Circus, Plymouth Effects of UV radiation and salinity on the intertidal macroalgae Palmaria palmata and Ulva lactuca; effects on photosynthetic performance, growth and pigments Elizabeth Beauchamp Project advisor: Maria