Effects of cadmium accumulation from suspended sediments and phytoplankton on the Oyster Saccostrea glomerata

Metals are accumulated by filter feeding organisms via water, ingestion of suspended sediments or food. The uptake pathway can affect metal toxicity. Saccostrea glomerata were exposed to cadmium through cadmium-spiked suspended sediments (19 and 93. µg/g dry mass) and cadmium-enriched phytoplankton (1.6-3. µg/g dry mass) and cadmium uptake and effects measured. Oysters accumulated appreciable amounts of cadmium from both low and high cadmium spiked suspended sediment treatments (5.9 ± 0.4. µg/g and 23 ± 2. µg/g respectively compared to controls 0.97 ± 0.05. µg/g dry mass). Only a small amount of cadmium was accumulated by ingestion of cadmium-enriched phytoplankton (1.9 ± 0.1. µg/g compared to controls 1.2 ± 0.1. µg/g). In the cadmium spiked suspended sediment experiments, most cadmium was desorbed from sediments and cadmium concentrations in S. glomerata were significantly related to dissolved cadmium concentrations (4-21. µg/L) in the overlying water. In the phytoplankton feeding experiment cadmium concentrations in overlying water were