UV-susceptibility of zoospores of the brown macroalga Laminaria digitata from Spitsbergen

The UV-susceptibility of zoospores of the lower sublittoral kelp Laminaria digitata was studied in the laboratory under varying fluence of spectral irradiance consisting of photosynthetically active radiation (PAR, 400-700 nm; = P), PAR + UV-A radiation (UV-A, 320-400 nm; = PA), and PAR + UV-A + UV-...

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Bibliographic Details
Published in:Polar Biology
Main Authors: Roleda, M Y, Luder, U H, Wiencke, C
Format: Article in Journal/Newspaper
Language:English
Published: 2010
Subjects:
SOUTH-PACIFIC KELPS
Ecology
EARLY-LIFE STAGES
INDUCED DNA-DAMAGE
Biodiversity Conservation
ABSORBING COMPOUNDS
ARCTIC LAMINARIALES
ULTRAVIOLET-RADIATION
PHOTOSYNTHETICALLY ACTIVE RADIATION
NORTHERN-HEMISPHERE
SACCORHIZA-DERMATODEA
LESSONIA-TRABECULATA LAMINARIALES
Arctic
Pacific
Spitsbergen
Online Access:https://pure.uhi.ac.uk/en/publications/7357a525-8fd5-4498-9480-0fae999fcae1
https://doi.org/10.1007/s00300-009-0733-z
Description
Summary:The UV-susceptibility of zoospores of the lower sublittoral kelp Laminaria digitata was studied in the laboratory under varying fluence of spectral irradiance consisting of photosynthetically active radiation (PAR, 400-700 nm; = P), PAR + UV-A radiation (UV-A, 320-400 nm; = PA), and PAR + UV-A + UV-B radiation (UV-B, 280-320 nm; = PAB). In vivo absorption of phlorotannin, localisation of phlorotannin-containing physodes, structural changes, DNA damage and repair, photosynthesis and germination of zoospores were measured after exposure treatments and after 2-6 days of recovery in dim white light. Photodegradation of phlorotannins was observed after extended exposure to ultraviolet radiation (UVR). The UV-protective function of extra- and intracellular phlorotannins was, therefore, observed only after 8 h, but not after 16-h UVR exposure. The energetic cost of photoprotection may have caused the delay in ontogenic development of zoospores after 8-h exposure to PA and PAB treatment; longer exposure time corresponding to 16-h PA and PAB treatment eventually lead to cell degeneration at 6 days post-cultivation. The formation of cyclobutane-pyrimidine dimers (CPDs), as indicator of DNA damage, was not blocked by the UV-absorbing phlorotannins during the 16-h PAB exposure and the inability for DNA damage repair was likely responsible for low photosynthetic recovery and spore mortality. The higher sensitivity of L. digitata zoospores to UVR compared to other kelps such as Saccorhiza dermatodea and Alaria esculenta confirmed our hypothesis that the depth distribution of adult sporophytes in the field correlates to the sensitivity of their corresponding early life history stages to different stress factors in general and UVR in particular.

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