REPRODUCTIVE-PERFORMANCE AND GROWTH-RESPONSE OF THE RED ALGA CERAMIUM-STRICTUM UNDER THE IMPACT OF PHENOL

The toxic effect of phenol on 3 stages in the reproduction of the red alga Ceramium strictum was studied, i.e. the formation of reproductive organs, fertilisation capacity and maturation of cystocarps. Male and female gametophytes were exposed separately to different concentratio ns of phenol for 3 d. Thereafter, experiments were conducted in which fertilisation and maturation of cystocarps were studied either with or without phenol present. The reproductive capacity was examined for al l possible crossings of exposed and unexposed male and female gametoph ytes and the results were measured as the number of cystocarps produce d. The development of reproductive organs on both female and male game tophytes was affected by phenol. The formation of female reproductive organs was about 20 times more sensitive than the reproductive functio ning of the male spermatangium. Thus, a 50 % reduction in reproductive capacity was estimated at around 5 to 7 and 100 mg phenol l(-1), resp ectively. The effect of phenol on the female gametophyte during fertil isation was decisive for the outcome of reproduction. The maturation o f cystocarps was affected to a lesser extent. After fertilisation had taken place in phenol, a 20 % decrease in reproductive capacity was ob served when the maturation of cystocarps had taken place in phenol rat her than in clean water. Thus, all 3 investigated phases were inhibite d by phenol. The strongest and most permanent negative effect was seen on the reproductive organs of the female gametophyte. Marked changes in the morphological appearance of the female plants were noted when e xposed for 3 different time periods, i.e. i, 3 and 10 d. At a concentr ation of 10 mg phenol l(-1) a loss of apical dominance was observed an d instead of the normal dichotomous growth with very few branches, mos t cells initiated an extra lateral branch. This response was more pron ounced at increasing phenol concentrations. A 24 h pulse exposure to p henol of more than 60 mg l(-1) influenced the growth pattern by as muc h as a week.