Influence of current velocity on cadmium accumulation by an aquatic moss and the consequences for its use as a biomonitor

Aquatic mosses are widely used as biomonitors of contaminant concentrations in running waters. The results of several previous studies suggest that me tal concentrations in mosses are influenced by current Velocity and that th is variable should be taken into account when mosses are used as metal biom onitors. However, in these studies, the purported influence of water Veloci ty was confounded by other uncontrolled variables. We conducted our study t o test the influence of current velocity on Cd accumulation by the riverine moss Fontinalis dalecarlica. We found no difference in Cd accumulation ove r 2 weeks by moss exposed in the laboratory to a constant Cd concentration over a wide range of current velocities (0.01-0.70 m s(-1)) that occur in t he field. Similarly, the results of a field experiment, in which we exposed F. dalecarlica in a Cd-contaminated creek to four current Velocities (0.05 -0.50 m s(-1)) confirmed that in nature Cd accumulation by this moss is not influenced by current velocity. We show-that a bioaccumulation model that ignores current velocity describes Cd accumulation by F. dalecarlica very w ell. Our results suggest that current velocity does not have to be consider ed when using aquatic mosses as metal biomonitors.