Estimating carrying capacity of quagga mussels (Dreissena rostriformis bugensis) in a natural system: A case study of the Boulder Basin of Lake Mead, Nevada-Arizona

Estimation of carrying capacity for bivalves is generally carried out for mussel culture systems wherein maximizing mussel numbers requires the consideration of both ecological and economic endpoints. We adapted an existing culture-system model to estimate potential carrying capacity of an invasive species, the quagga mussel (Dreissena rostriformis bugensis) in the Boulder Basin of Lake Mead, Nevada. We parameterized the model using both field measurements and known quantities previously published in the literature. To make this model most useful to ecologists and managers, we provide a detailed description and derivation, as well as an example calculation for the model. The model is based on mean Chlorophyll a concentrations in the Boulder Basin of Lake Mead, and the number of quagga mussels needed to filter a given reduction in food particles from the water column. Estimates ranged from a total of 1.51 x 10(12) mussels with a net reduction of 50% of food particles to 1.02 x 10(13) mussels when the net reduction was at the threshold level of survival (0.017 mu g/L). Limitations to the model and potential environmental and ecological considerations are discussed.