Bioaccumulation of Heavy Metals by Damselfly Nymphs (Enallagma boreale) in Spring Meadow Lake, Lewis and Clark County, Montana

Abstract

This study was conducted to determined if damselfly nymphs, specifically, Enallagma boreale, inhabiting the shoreline of Spring Meadow Lake (SML) are experiencing bioaccumulation of heavy metals (Mn, Pb, As, Zn). SML is located in Lewis and Clark County, Montana, approximately 1.5 kilometers west of Helena. Previous studies of SML reveal that elevated levels of heavy metals are present in the sediment at specific sites along the shoreline. At other sites along the shoreline, the levels are consistent with background values. Both sediment and biological samples were collected from sites at SML and a reference wetland, Forest Lake. Metal levels were determined by Inductively-coupled Plasma Atomic Emission Spectrometry. The results indicate that there is a significant correlation between elevated levels of Mn, Pb, and As in the sediment and in the biological samples. However, there was no correlation between levels of Zn in the sediment and in the biological samples. It is observed that the environment with elevated levels of heavy metals, which the damselfly nymphs inhabit, is a significant source of bioaccumulation of Mn, Pb, and As, whereas bioaccumulation of Zn did not occur.