Arsenic distribution and speciation in Daphnia pulex

►Most of the arsenic signal is concentrated in the gut of the organism Daphnia pulex. ►Inorganic arsenic measured in Daphnia pulex comes from ingested food particles. ►Collected Daphnia pulex contain up to 34% organoarsenicals; mainly arsenosugars. ►Zooplankton are the first freshwater organisms to create organoarsenicals.