Modeling the effect of invasive quagga mussels on the spring phytoplankton bloom in Lake Michigan

Abstract The disappearance of the spring phytoplankton bloom in Lake Michigan has been attributed in some studies to the direct effect of quagga mussel filter-feeding. We applied a biophysical model to test whether the observed reduction in the spring bloom can be explained by direct effects of quagga mussel grazing. We developed a 1-D column biological model that simulated light and temperature limitation on phytoplankton growth, vertical mixing, and grazing by zooplankton and quagga mussels. We applied the 3-D finite volume coastal ocean model (FVCOM) to provide vertical mixing, with two scenarios of atmospheric forcing: (a) North American Regional Reanalysis (NARR) and (b) station interpolation using the Natural Neighbor Method. Simulated development of the spring bloom and formation of the deep chlorophyll layer in the early summer stratified period were consistent with observations. Increased strength of winter stratification (surface