Planktonic foraminiferal assemblages preserved in surface sediments correspond to multiple environment variables

Abstract

Here we investigate the relationships between modern planktonic foraminiferal species assemblages from Atlantic and Pacific core-top sediment samples and 35 water-column and preservation properties using Canonical Correspondence Analysis (CCA). CCA finds two faunal dimensions (axes) that are most highly correlated to the environmental variables, and describes each axis in terms of the best linear combination of environmental variables. CCA Axis 1 (30.4% of the faunal variance) is related primarily to mean annual sea-surface temperature (SST, r=−0.96). CCA Axis 2 (7.9% of the faunal variance) is related to environmental variability associated with an inverse relationship between SST and surface salinity, as well as pycnocline phosphate concentrations, the seasonal range in nitrate concentrations, water depth, and chlorophyll concentrations at the sea surface. Based on this clustering of nutrient and chlorophyll on Axis 2, we infer an ecological response to oceanic fertility. No evidence is found for a unique dissolution influence, suggesting that sea-floor carbonate ion concentration cannot be estimated reliably from planktonic foraminiferal assemblages. Our results support the use of foraminiferal assemblages to estimate mean annual SST.