Phlorotannins as UV-protective substances in early developmental stages of brown algae

• Main Author: Steinhoff, Franciska S.
• Other Authors: Bischof, Kai, Wiencke, Christian
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2010
• Subjects: 570; 570 Life sciences; biology; ddc:570; Arctic; Kongsfjord*; Kongsfjorden; Spitsbergen
• Online Access: https://media.suub.uni-bremen.de/handle/elib/2842; https://nbn-resolving.org/urn:nbn:de:gbv:46-diss000119984

Communities of macro- and microalgae present a dominant group of coastal benthic ecosystems. Macroalgae exhibit a complex developmental cycle involving microscopic life stages which are fully exposed to environmental factors such as UV radiation (UV) and water temperatures displaying the most sensitive stage of the entire macroalgal life-cycle. In the last 50 years, the ozone content in the atmosphere has significantly diminished due to growing emissions of synthetic chlorofluorocarbon molecules. At the same time, global mean temperature increased due to the so-called green house effect. These global environmental changes may affect ecosystems to a hitherto unknown extent. The aims of the present study therefore involve the depiction of acclimation to UVR and PAR in the protective and metabolic mechanisms of brown algal juvenile life stages of the species Alaria esculenta, Laminaria digitata, Saccharina latissima and Saccorhiza dermatodea as well as the species' adaptive potential to enhanced temperatures. Including a comparative approach of field and laboratory experiments, the present study integrates various radiation regimes and intensities, temperature experiments and exposure times. For a broader understanding of effects, a variety of methods investigating e.g. intra- and extracellular levels of phlorotannins by the Folin-Ciocalteu method, fatty acid determination by gas chromatography, determination of reactive oxygen species and electron microscopy was applied to several juveniles of various Arctic macroalgae from Spitsbergen (Kongsfjorden). Results reveal that the sensitivity to visible and UVR of various macroalgal species is determined by their radiation tolerance and the protective potential of their parental tissue. As still only few data are available on interactive effects of PAR, enhanced UVR and temperatures, predictions of future consequences for algal recruitment and survival as well as on the community level remain difficult. While enhanced UVR in combination with low PAR in the laboratory ...