DIFFERENCES IN DISPERSAL ABILITIES OF HAPLOID AND DIPLOID SPORES OF GRACILARIA-VERRUCOSA (GRACILARIALES, RHODOPHYTA)

In some red algae, the establishment of new fixed individuals is due to two kinds of spores: haploid spores producing gametophytes and diploid spores producing sporophytes. Spore dispersal abilities were studied in order to understand settlement patterns in algal populations. Spore dispersal depends principally on their survival and how long they remain viable whilst suspended in the water column. It has been suggested that there is a positive correlation between spore size and their sedimentation rate. In Gracilaria verrucosa haploid spores are smaller than diploid ones. Nevertheless when submitted to a slow controlled water current, spore size had no effect on their dispersal. Conversely, under different light conditions, haploid spores have a better survival and remain free-floating longer than diploid ones, thus haploid spores could have better dispersal abilities than diploid ones.