Supplement to: Trimborn, Scarlett; Brenneis, Tina; Hoppe, Clara Jule Marie; Laglera, Luis Miguel; Norman, Louiza; Santos-Echeandía, Juan; Völkner, Christian; Wolf-Gladrow, Dieter A; Hassler, Christel S (2017): Iron sources alter the response of Southern Ocean phytoplankton to ocean acidification. Marine Ecology Progress Series, 578, 35-50, https://doi.org/10.3354/meps12250