This project aims to identify the environmental controls of iron reducing microorganisms in sediments situated close to Fourcade Glacier in Potter Cove, King George Island/Isla 25 de Mayo, in the Antarctic Peninsula. The samples were obtained during the Antarctic summer campaign to the Argentinian Carlini Base of the Island between January and March 2019. Samples were obtained using either push cores by SCUBA divers from the Argentinian Diving Division or with a sediment corer (UWITEC, Austria). Live samples were stored at 2 degrees C (near in situ temperature) until transport to the home laboratory where they were used for incubation experiments. The data in this project supports two studies: (1) Investigation of the effect of macroalgae (as pool of organic matter) and AQDS (humic substance analog) on iron reduction and associated microorganisms using slurry incubations and RNA-stable isotope probing with 13C-labeled acetate or bicarbonate. Activities in sediment from two different sampling locations (STA10, STA14) were compared. (2) Identifying acetate utilizing iron reducers with RNA-stable isotope probing in sediments located closely at the terminating glacier (STA13).