The simulation of phytoplankton in shallow and deep lakes using PROTECH

A phytoplankton community model, Phytoplankton RespOnses To Environmental CHange (PROTECH), was used to simulate a shallow and deep lake and incorporated an additional eddy diffusivity (Kd) effect. This new version of the model, PROTECH-D, was tested against observed data from two lakes and the previous incarnation of the model, PROTECH-C. Results suggested that for the shallow lake simulated, PROTECH-D was better because it captured subtle developments within blooms that were missed by PROTECH-C. However, PROTECH-D struggled to simulate the thermal structure of the deep lake, compared to PROTECH-C, although the predicted total chlorophyll a was close to that observed. It was concluded that using a single value of Kd all year and at all depths may be an oversimplification and difficult to estimate. Nevertheless, from a biological perspective, PROTECH-D, like PROTECH-C before it, was successful at modelling the key events in the annual development of a phytoplankton community.