Thwaites Glacier's retreat is driven by warm ocean water melting its ice shelf. Seafloor-dwelling marine protists, benthic foraminifera, reflect their environment. Here, ice margins, oceanography, and sea ice cover control live foraminiferal populations. Including dead foraminifera in the analyses shows the calcareous test preservation's role in the assemblage make-up. Understanding these modern communities helps interpret past glacial retreat controls through foraminifera in sediment records.