Ecological and physiological investigations about the impact of UV radiation (UVR) on the succession on benthic primary producers in Antarctica

UV radiation (UVR = 280 – 400 nm) impairs a variety of biological processes in algae. It was therefore hypothesized that UVR also affects ecosystem structure. However, UVR research on marine algae has hitherto focussed mainly on physiological effects at the organism level (macroalgae) or on soft-bottom communities and phytoplankton (microalgae). The aims of the study were to detect UVR effects on benthic algal communities at King George Island, Antarctica, by combining laboratory approaches and field-experiments. The study focused on the UV susceptibility of the early successional stages of macro- and microalgae.

In 2.5 and 3.5 months field experiments with artificial substrate the interactive effects of UVR and grazing on early life stages of an intertidal algal community were studied. The results showed a reduction in both, macro- and microalgal biomass due to grazing. The most important grazer was the limpet Nacella concinna which on the other hand increased macroalgal richness and diversity due to an enlarged spatial heterogeneity of the system.

While microalgal biomass and species composition were unaffected by UVR, both UV-A and UV-B radiation negatively affected macroalgal succession. UVR decreased the density of green algal recruits in the first 10 weeks of the experiment, whereas the density of red algal recruits was significantly depressed by UVR at the end of the study. Macroalgal diversity and species richness were significantly higher in UV depleted assemblages at the end of the study. Furthermore, species composition differed significantly between the UV depleted and the UV exposed treatment.

Laboratory experiments with subtidal microalgal soft-bottom communities showed transient negative effects on photosynthetic efficiency and cell number, which, however, disappeared later. No permanent negative effects could be observed. Parameters like growth and biomass were generally unaffected by UVR.

Spores and gametes of different brown, green and red algae were influenced by UVR. Most sensitive were sublittoral species, while the least sensitive species occurred in the supralittoral. UVR influence the zonation patterns of the algae at the coastline and is at least partly responsible for the upper distribution limit of the respective algal species. Generally propagules are low light adapted and react with a decrease of photosynthetic efficiency to UVR. Species from the upper sublittoral could not recover their photosynthetic efficiency completely after 48 h under low light conditions. Intertidal algal recovered faster and showed in relation to sublittoral algal propagules a lower DNA damage after UV exposure. Red algal spores exhibited mycosporin-like amino acids which absorb UVR and therefore protect the cell. This might be a possible explanation of the low UVR sensitivity of these algae.

Scientists

Prof. Dr. Christian Wiencke
Alfred-Wegener-Institute Bremerhaven

Prof. Dr. Dieter Hanelt
Biocenter Klein Flottbek
University of Hamburg

Dr. Angela Wulff
Dept. of Marine Ecology
Göteborg University

Dr. Michael Roleda
Institute for Polar Ecology
University of Kiel

Dr. Katharina Zacher
Alfred-Wegener-Institute Bremerhaven

Research areas

King George Island (South 62°, West 58°), Dallmann Laboratory/Jubany Base

Publications

Zacher K, Wulff A, Molis M, Hanelt D, Wiencke C (2007) UV radiation and consumers effects on a field-grown intertidal macroalgal assemblages in Antarctica, Global Change Biology, 13(6): 1201-1215

Zacher K, Roleda, MY, Hanelt D, Wiencke C (2007) UV effects on photosynthesis and DNA in propagules of three Antarctic seaweeds (Adenocystis utricularis, Monostroma hariotii and Porphyra endiviifolium), Planta, 225(6): 1505-1516

Zacher K, Hanelt D, Wiencke C, Wulff A (2007) Grazer and UV radiation effects on an Antarctic intertidal microalgal assemblage, Polar Biology, 30(9): 1203-1212

Roleda MY, Zacher K, Wulff A, Hanelt D, Wiencke C (2007) Photosynthetic performance, DNA damage and repair in gametes of the endemic Antarctic brown alga Ascoseira mirabilis exposed to ultraviolet radiation, Austral Ecology, 32(8): 917-926

Zacher K (2007) Effects of UV radiation on Antarctic benthic algae - with emphasis on early successional stages and communities (Effekte von UV-Strahlung auf antarktische benthische Algen - mit Schwerpunkt auf jungen Entwicklungsstadien und Gemeinschaften), Berichte zur Polar- und Meeresforschung 567, 191 pp., Bremen University, Dissertation

Wulff A, Zacher K, Yusif A, Hanelt D, Wiencke C (2008) UV radiation- a threat to Antarctic benthic marine diatoms? Antarctic Science, 20(1): 13-20

Richter A, Wuttke S, Zacher K (2008) Two years of in situ UV measurements at Dallmann Laboratory/ Jubany Base in: Wiencke, C., Ferreyra, G., Abele, D., Marenssi, S. (eds): The Potter Cove coastal ecosystem, Antarctica. Synopsis of research performed 1999-2006 at the Dallmann Laboratory and Jubany Station, King George Island (Isla 25 de Mayo). Berichte zur Polar- und Meeresforschung 571: 12-19

Roleda MY, Zacher K, Campana GL, Wulff A, Hanelt D, Quartino ML, Wiencke C (2008) Photosynthetic performance and impact of ultraviolet radiation on the reproductive cells of Antarctic macroalgae, in: Wiencke, C., Ferreyra, G., Abele, D., Marenssi, S. (eds): The Potter Cove coastal ecosystem, Antarctica. Synopsis of research performed 1999-2006 at the Dallmann Laboratory and Jubany Station, King George Island (Isla 25 de Mayo). Berichte zur Polar- und Meeresforschung 571: 254-262

Zacher K, Campana G (2008) UV radiation and consumer effects on an intertidal and subtidal macroalgal assemblage: a comparative study, in: Wiencke, C., Ferreyra, G., Abele, D., Marenssi, S. (eds): The Potter Cove coastal ecosystem, Antarctica. Synopsis of research performed 1999-2006 at the Dallmann Laboratory and Jubany Station, King George Island (Isla 25 de Mayo). Berichte zur Polar- und Meeresforschung 571: 287-294

Wulff A, Zacher K (2008) Short-term effects of UV radiation on benthic marine diatoms, in: Wiencke, C., Ferreyra, G., Abele, D., Marenssi, S. (eds): The Potter Cove coastal ecosystem, Antarctica. Synopsis of research performed 1999-2006 at the Dallmann Laboratory and Jubany Station, King George Island (Isla 25 de Mayo). Berichte zur Polar- und Meeresforschung 571: 295-301

Wulff A, Roleda MY, Zacher K, Wiencke C (accepted) Exposure to sudden light burst after prolonged darkness – a case study on benthic diatoms in Antarctica (Diatom Research)

Roleda MY, Zacher K, Wulff A, Hanelt D, Wiencke C (2008) Susceptibility of spores of different ploidy levels from Antarctic Gigartina skottsbergii (Gigartinales, Rhodophyta) to ultraviolet radiation. Phycologia 47(4)

Wulff A, Roleda MY, Zacher K, Wiencke C (accepted) UV radiation effects on pigments, photosynthetic efficiency and DNA of a semi-natural Antarctic marine benthic diatom community (Aquatic Biology)

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Research funding organisation

German Research Foundation

Project numbers: WI 646/8
Funding period: July 2003 – July 2006