Wavelength Dependent Effect of High Irradiance on Early Sporophytes of Laminaria hyperborea (Phaeophyta)

Algae > Volume 8(2); 1993 > Article

Algae 1993;8(2): 199-205.

Tae-Jun Han

Port Erin Marine Laboratory, University of Liverpool

ABSTRACT

In laboratory culture, growth of early sporophytes of Laminaria hyperborea was inhibited at 180 μmol m super(-2)s super(-1) of continuous white light provided from Polylux 4000 fluorescent tubes. There was a growth inhibition in cultures covered by a UV filter at 168 μmol m super(-2)s super(-1). Polylux 4000 was inhibitory to the growth of L. hyperborea early sporophytes at 110 μmol m super(-2)s super(-1), but Northlight of higher irradiance was found not to be inhibitory. The former light source contains more quanta in blue and green waveband than does the latter. At 60 μmol m super(-2)s super(-1), blue light was unfavourable to the growth of early sporophytes compared with green light, partly explaining the growth inhibition found not in Northlight but in Polylux 4000 in terms of the additional blue quanta. Plants exposed to sunlight without a UV filter showed much higher mortality than those with a UV filter. After 21 min exposure, however, a significant decrease in survival of L. hyperborea early sporophytes was observed even in UV-fitered plants. When plants were exposed to sunlight adjusted in its irradiance to 90-100 μmol m super(-2)s super(-1) under three different coloured filters, 7 min exposure resulted in the highest mortality in blue filter-covered plants.

Key words: blue light, inhibition, Laminaria hyperborea, mortality