The sensitivity of surface chlorophyll (Chl) and bottom water dissolved oxygen (DO) to total nitrogen (TN) load was investigated using a Bayesian?based process model fit to data from a range of estuaries. The model was used to test if the sensitivity of DO depletion to TN loads is dependent only on factors controlling the sensitivity of surface Chl, or if additional factors are important. Results indicate that separate processes control Chl and DO sensitivity, and that these sensitivities vary among estuaries. Analysis of fitted parameters across estuaries showed that Chl sensitivity to TN loading was positively correlated with water residence time, and DO sensitivity to Chl was positively correlated with relative mixing depth.