Over the past year our research on cadmium has reached a turning point. We have shown in the past that Cd promotes the growth of diatoms under low zinc conditions as the result of the synthesis of a Cd-carbonic anhydrase. We have finally obtained the full DNA sequence for this enzyme (the first Cd enzyme discovered) and are in the process of characterizing it. We have also obtained preliminary evidence for an extracellular Cd-alkaline phosphatase in coccolithophores. The biochemical utilization of cadmium by these two organisms is, we believe, the key to the ocean biogeochemistry of Cd and also, perhaps, to the ecology of these dominant phytoplankton taxa.