Fig. (7) Relative abundance variation of low-oxygen tolerant benthic foraminifers (= PEB) in core MRD05-4 from the Louisiana Shelf (Fig. 4). The record is a combination of data from a box core and gravity core from the same locality (see discussion in Osterman et al. (2008) [47]). Chronology for the upper part of the record is based on ²¹⁰Pb measured in the box core. The single date indicated at 220cm is based on two radiocarbon dates [47]. High PEB values in the top part of the record (last 50 years) represent development of hypoxia near the Mississippi River due to increased nutrient loading related to the use of fertilizer in the Mississippi River Basin. High values of PEB below 40 cm depth represent development of low-oxygen bottom water conditions that likely represent increased discharge from the Mississippi River of the Atchafalaya River and thus indicate past floods that transported more natural nutrients to the Louisiana Shelf. No dates are available above 240 cm in the gravity core so the timing of the individual “flood events” indicated by high PEB values cannot be estimated.