Chione (austrovenus) stutchburyi, a New Zealand cockle, as a Bio-indicator for lead pollution

The shellfish Chione (Austrovenus) stutchburyi has been studied as a bio-indicator for lead in an estuarine environment near Christchurch, New Zealand. Over four years the mean lead level in the soft tissue was 1·16 μg g⁻¹. The levels responded to significant rainfall events in the catchment area. Over the four years a fall in lead levels corresponded to reduced lead inputs into a river feeding the estuary. In addition to climatic and lead source changes, seasonal effects and shell size also need to be considered, as lead levels fall in the early summer and are elevated in small shellfish. The use of the shell as a bio-indicator for lead necessitates sectional and surface shell analysis rather than whole shell analysis. Both shell age and depth into the shell are variables that associate with lead.