Figure 7. Estimated values of d¹⁸O in LIS water as a function of mixing between sea water and river water. The d ¹⁸O composition of biogenic carbonate reflects the water temperature during growth of the test, the isotopic composition of the water, and species-specific fractionation effects. Variations in the d ¹⁸O composition of a specific species of foraminifera in LIS depend on the global sea water isotopic composition (which varies as a function of global ice volume), the local mixing-ratio between seawater and continental run off, and bottom water temperature.