Uptake of Nickel and Zinc by the Zebra Mussel Dreissena polymorpha

Abstract.

Short-term experiments with nickel and zinc radioisotopes showed that the zebra mussel Dreissena polymorpha takes up both “dissolved” (<0.45 μm) and particulate fractions of these metals in water. Uptake of particulate nickel was significant (despite a relatively low affinity of nickel for particulate matter), though less important than uptake of dissolved nickel. The relative importance of dissolved and particulate zinc varied from an almost exclusive uptake of dissolved zinc to uptake of particulate zinc only. This variability may reflect a dependence on the composition of the suspended particulate material, in line with the observation that zinc uptake and bioaccumulation were higher in high-turbidity water than in low-turbidity water. Metal excretion differed between the two metals; more than half of the accumulated zinc was excreted in twenty four hours, while no nickel excretion was evident. The mussels removed a larger proportion of total watercolumn zinc than of total watercolumn nickel. Of the metal removed from the watercolumn, a majority of the zinc was biodeposited (as feces/pseudofeces) while most of the nickel was bioaccumulated. These results indicate that the introduction of the zebra mussel will result in element-specific decreases of watercolumn metal levels, increases in metal bioaccumulation and increases in metal biodeposition. Results also indicate that D. polymorpha tissue metal levels obtained in biomonitoring programs will generally reflect both dissolved and particulate metal levels.