Description: 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.
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Origins: /Bund/UBA/UFORDAT
Tags: Hirsch ? Benthal ? Phytoplankton ? Rotalgen ? UV-Strahlung ? Arktisches Meereis ? UV-Belastung ? Makroalgen ? Gebäude ? Mikroalgen ? Photosynthese ? Sportinfrastruktur ? Wirkung ? Strahlung ? Insel ? Antarktis ? Biologische Aktivität ? Artenvielfalt ? Stratosphäre ? Studie ? Artenzusammensetzung ? Wirkungsforschung ? Algen ? Meeresgewässer ? Beweidung ? Antarktisforschung ? Wirkung ? Ballungsraum ? Laboruntersuchung ? Ökosystem ? Lebewesen ? Biomasse ? Forschung ? Forschungseinrichtung ? Freilandversuch ? Blattgemüse ? Physiologische Wirkung ? Sporen ? Diversität ? Annäherung ? Verteilung ? Wachstum [biologisch] ? angepasst ? eingeschränkt ? größt ? permanent ? sonstig ? wichtig ? Überempfindlichkeit ? Art [Spezies] ? Ausstellungsstück ? Dichte ? Ergebnis ? Experiment ? Abnahme ? Gemeinschaft ? Produzent ? Schädigung ? Sukzession [Ökologie] ? Untersuchung ? Vermehrung ? Verringerung ?
Region: Bremen
Bounding boxes: 8.83333° .. 8.83333° x 53.08333° .. 53.08333°
License: cc-by-nc-nd/4.0
Language: Englisch/English
Time ranges: 2003-01-01 - 2006-07-30
Webseite zum Förderprojekt
http://www.spp-antarktisforschung.de/ (Webseite)Accessed 1 times.