Bioaccumulation of heavy metals by aquatic macro-invertebrates of different feeding guilds: a review

The available literature on heavy metal bioaccumulation by freshwater macro-invertebrates has been analysed. A very uneven data distribution was found. Ephemeroptera and Diptera are the most commonly investigated orders of insect larvae, whilst many orders are not represented at all. The collector–gatherer and predator feeding guilds are more frequently investigated than other guilds. Furthermore, Zn, Cu, Pb and Cd are the most intensively researched heavy metals, and only infrequent investigations of other metals are documented. Relationships between metal concentrations in the animals and levels in sediments and waters were determined from the pooled data for three feeding guilds. No one relationship represents how each metal interacts within the feeding guilds. Each of the four metals (Zn, Cu, Pb and Cd) displays a unique relationship between metal concentrations in sediments or waters with those in individual feeding guilds of macro-invertebrates, indicating the relative importance of different sources of metals to the different feeding types. Biomagnification of Zn, Cu, Pb and Cd has been demonstrated not to occur between these guilds.