ABSENCE OF ALLELOPATHIC EFFECTS OF CHARA ON PHYTOPLANKTON INSITU

Chemical compounds isolated from Chara have been shown to inhibit algal photosynthesis in laboratory experiments, supporting the concept of negative allelopathy in Chara. However, evidence for this phenomenon in situ has not been obtained. Studies of the relationships between lake phosphorus levels and phytoplankton biomass in six Chara lakes demonstrated that these lakes have a phytoplankton biomass of predictable size. This indicates that Chara does not release allelopathic compounds in situ. The reported densities of epiphytes on these plants also indicate the absence of allelopathy by Chara in situ. © 1990.