The Effects Of Quagga Mussels On Phosphorous-Dependent Growth Of Cladophora In Near-Shore Lake Michigan

Abstract

Nuisance growth of the filamentous green alga, Cladophora glomerata, has been a problem in Lake Michigan for decades. Phosphorous loading restrictions implemented throughout the Great Lakes region in the 1970’s were successful in reducing the standing crop levels of Cladophora. Since the early 2000’s there has been a resurgence of Cladophora growth in near-shore Lake Michigan. This resurgence has been attributed to the activities of the invasive species of mussels known as Dreissena rostriformis burgensis, which was first discovered in Lake Michigan in 1998. This paper builds on the Great Lakes Cladophora Model developed by Tomlinson et.al. in 2010; and explicitly takes into account the feeding activity of the mussel population which supplies phosphorus to the benthic region that stimulates Cladophora growth. The new model demonstrates good agreement between simulation and measured data for Cladophora biomass during a growing season. The mechanistic model is used to provide a quantitative analysis of the contribution of and sensitivity to key environmental factors in Cladophora biomass. By keeping track of the total sloughed off Cladophora biomass this work attempts to quantify the exposure of Lake Michigan beaches to fouling by nuisance alga.