Marine Amphipod Toxicity to Cobalt Spiked into Water and Sediment

Client:  Cobalt Development Institute  

Description of Work 

EcoAnalysts staff was hired by the Cobalt Development Institute (CDI) to conduct a laboratory study to determine the toxicity of cobalt to sediment dwelling marine amphipods. The laboratory analysis was undertaken because while there is more information available on the overall toxicity of cobalt to freshwater organisms, less is known about the relative toxicity of cobalt to marine organisms. The toxicity of cobalt to marine organisms was investigated by exposing two different behavioral types of marine amphipods to cobalt. These species of amphipods interact with the sediment differently and those behavioral differences may affect how they are exposed to cobalt. One group of amphipods are free burrowing (Rhepoxynius abronius) and the other (Ampelisca abdita) live in tubes. We hypothesized that the tube dwelling amphipods would be less susceptible to cobalt in the porewater and sediment while the free burrowing amphipods would be more susceptible. The toxicity of cobalt to marine organisms was evaluated over the course of two different testing programs conducted in 2013 using direct spiking methods and again in 2016 using indirect spiking methods (Besser et al. 2011). The study also compared the response of amphipods to freshly spiked sediment versus spiked sediment that is aged under anaerobic conditions prior to exposure of amphipods.