Modeling zebra mussel impacts on water quality of Seneca River, New York

The concentrations of dissolved oxygen and chlorophyll have declined in the Seneca River, New York since 1991 as a result of zebra mussel respiration and filtering. Recently measured data were used to approximate flux rates of zebra mussel respiration, filtering, and phosphorus and ammonia mobilization. A model is developed that for the first time links dissolved oxygen, phytoplankton growth, and zebra mussel respiration and filtering. Good agreement is attained between the model calculations and longitudinal profiles of both dissolved oxygen and chlorophyll measured at low flow during 1997-1999. Flux rates derived from these analyses are consistent with results from other studies when normalized on the basis of zebra mussel number and tissue dry weight. Kinetic formulations for the zebra mussels are developed that describe respiration and filtering rates as a function of density, size distribution, and dissolved oxygen concentration. Several plausible test scenarios are examined using the model that indicate that both zebra mussel numbers and size distributions have a profound effect on the water quality of the Seneca River and therefore have important management and planning ramifications.