The toxicological interaction between ocean acidity and metals in coastal meiobenthic copepods

► Increased atmospheric CO2 concentrations result in greater dissolution of CO2 in seawater and ultimately to ocean acidification. ► This work is first to examine the sensitivity of coastal harpacticoid copepods to acidity. ► We studied HCl and CO2 toxicities on two species of copepods: one from muddy and the other from sandy environment. ► We also studied interaction between CO2 and heavy metals (Cd and Cu).