Simulating the 1998 spring bloom in Lake Michigan using a coupled physical‐biological model

Abstract

[1] A coupled physical-biological model is used to simulate the ecosystem characteristics in Lake Michigan. The physical model is the unstructured grid, Finite-Volume Coastal Ocean Model (FVCOM). The biological model is a NPZD model, including phosphorus as the nutrient, which is the limiting element in Lake Michigan, phytoplankton, zooplankton and detritus. The models are driven by observed hourly meteorological forcing in 1998 and the model results are calibrated by satellite and in situ data. The main physical and ecological phenomena in the spring of 1998 are captured. During March to May, a circle-like phytoplankton bloom appears in southern Lake Michigan, which looks like a 'doughnut'. The formation mechanisms of the prolonged spring bloom are investigated. It is confirmed that the phytoplankton bloom is forced by rapidly increasing temperature and light intensity in spring. The thermal front that develops in spring inhibits the transport of nutrients and phytoplankton from the nearshore to the deeper water. The wind-driven gyre circulation in southern Lake Michigan induces significant offshore transport, which contributes to the establishment of the circular bloom.

Influence of invasive quagga mussels, phosphorus loads, and climate on spatial and temporal patterns of productivity in Lake Michigan: A biophysical modeling study

“…The NPZD model was implemented using the FVCOM general ecosystem module (GEM), which allows the user to specify biological model compartments within a flexible framework, and solves the three‐dimensional scalar advection‐diffusion equations on the FVCOM unstructured grid. FVCOM‐GEM has been applied previously to study spatially‐resolved plankton dynamics in coastal marine systems (Tian and Chen ; Ji et al a,b ) and in Lake Michigan (Luo et al ) using NPZD and NPZ models. We added the dreissenid mussel compartment to the FVCOM‐GEM code (described below).…”

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

“…An application of FVCOM to Lake Michigan with coupled nutrient-phytoplankton-zooplankton-detritus model (NPZD), focused on simulation of the spatial distribution of surface chlorophyll prior to the quagga mussel invasion; they attributed formation of the 'doughnut' shaped spring phytoplankton bloom observed in satellite imagery primarily to physical processes, including constrained nearshore-offshore transport by the thermal bar (Luo et al, 2012). An application of POM with a coupled lower food web model focused on the impacts of sediment resuspension events on the lower food web in March during the pre-mussel period, but did not extend simulations into the summer stratified period (Chen et al, 2004).…”

A Hybrid Lagrangian-Eulerian Particle Model for Ecosystem Simulation

“…445 is the light attenuation coefficient that accounts for the impact of water turbidity, 446 phytoplankton, and detritus on the light attenuation. Model parameterization is based on 447 literature review [Fahnenstiel et al,1989;Nicklisch et al 2007;Luo et al 2012 be discerned from the fact that the eigenvalues have a positive real part [Edwards et al 459 2000]. However, at unstable mid-depths the fields return to equilibrium, as a damped 460 oscillator due to vertical mixing, consistent with complex eigenvalues from linear 461 stability analysis [Edwards et al 2000].…”