Effects of UV radiation and temperature on growth of germlings of three species of Fucus (Phaeophyceae)

Abstract

Measurements of relative growth rates (RGR) of germlings of three species of Fucus (Fucales, Phaeophyceae) collected in Helgoland (North Sea, Germany) were carried out in the laboratory in order to determine the effects of different ultraviolet radiation (UVR, λ=280–400 nm) conditions, UVR doses and temperatures. High ultraviolet-B radiation (UVBR, λ=280–315 nm) levels and low temperature, as independent factors, led to a species-specific reduction in RGR which appears to be related to the vertical distribution of the species in the intertidal zone. The inhibition of RGR ranged from 10% to even death of the germling. For the most sensitive species, high temperature in combination with a high dose of UVBR caused the death of the germlings, whereas at low temperature germlings were able to survive. This suggest growth-related temperature dependence of sensitivity to UVBR.