Uptake of the cyanobacterial hepatotoxin microcystin-LR by aquatic macrophytes

Ceratophyllum demersum, Elodea canadensis, and Vesicularia dubyana were exp osed to C-14-microcystin-LR in order to study the uptake of this cyanobacte rial hepatotoxic cyclic heptapeptide by aquatic plants. After exposing the plants to the toxin for 24 h, we found a significant uptake in the range of 0.6 to 1.75 % of the applied radioactivity. Microcystin-LR uptake was time -dependent after an initial exposure time of about 12 h. Radiolabel was mai nly detected in the leaf and shoot tissues of E. canadensis, with lowest am ounts in the stem and root tissues. The results indicate that microcystin-L R can accumulate in aquatic plants and raise the possibility that microcyst ins could be thereby transferred into the aquatic food web.