Responses of Antarctic Iridaea cordata (Rhodophyta) tetraspores exposed to ultraviolet radiation

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Erscheinungsjahr:
2009
Medientyp:
Text
Schlagworte:
  • Antarctica
  • DNA damage
  • P-E curve
  • mycosporine-like amino acids
  • photosynthetic efficiency
  • tetraspores
  • ultraviolet radiation
Beschreibung:
  • In Antarctica ozone depletion is highest during spring, coinciding with the reproduction of many seaweed species. Propagules are the life-stage of an alga most susceptible to environmental perturbations. Therefore, fertile thalli of Iridaea cordata (Turner) Bory (Rhodophyta) were collected in the eulittoral of King George Island (Antarctica) to examine spore susceptibility to ultraviolet radiation (UVR). In the laboratory, freshly released tetraspores were exposed to photosynthetically active radiation (PAR) (400-700 nm), PAR+UV-A (320-700 nm) or PAR+UV-A+UV-B (280-700 nm). Photosynthetic efficiency was measured during 1-8 h of exposure and after 48 h of recovery. Additionally, mycosporine-like amino acids (MAAs) and DNA damage were determined. Saturating irradiance of photosynthesis of freshly released tetraspores was 57 μmol photons m -2 s-1. Exposure to increasing fluence of PAR reduced photosynthetic efficiency. UVR further decreased the photosynthetic efficiencies of the tetraspores but spores were able to recover completely after UVR exposure and 2 days post-cultivation under low PAR. DNA damage was minimal and lesions were effectively repaired under photoreactivating light. Concentrations of the MAAs shinorine and palythine were higher in tetraspores treated with UVR than in spores only exposed to PAR. Generally, the tetraspores show a good UV tolerance. This flexible response of the tetraspores of this species to changing radiation conditions enables the alga to grow along a considerable depth gradient from the sublittoral to the eulittoral where they can be exposed to enhanced UVBR under conditions of stratospheric ozone depletion. © 2009 Japanese Society of Phycology.
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  • info:eu-repo/semantics/closedAccess
Quellsystem:
Forschungsinformationssystem der UHH
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oai:www.edit.fis.uni-hamburg.de:publications/cde9b46e-16fd-483d-8cf4-f116c9606714