Immunotoxicity in ascidians: Antifouling compounds alternative to organotins

► Immunotoxic effects of Cu(I) and Irgarol 1051 were studied in a colonial ascidian. ► Both, commonly present in antifouling paints, induce dose-dependent immunosuppression. ► Cu(I) is more toxic than Irgarol, inhibits phagocytosis and affects Ca2+ homeostasis. ► Both change membrane permeability, induce apoptosis and alter hydrolases activities. ► When co-present they act on different subcellular targets.