Forecasts of water clarity, nutrient concentrations, and plankton biomass are needed by management for aquatic ecosystems to ensure consistent ecosystem services for stakeholders. The purpose of this study was to develop models of water clarity and nutrient concentrations for a brackish, man-made 300 million gallon lagoon located on Oahu, Hawaii. In 2013, half of the lagoon was dredged, and in 2014 monthly sampling began on several metrics of water clarity, nutrient concentrations, and the cover of an allelopathic macroalgae - Chara zeylanica. Dredging resulted in a two year period of decreased Chara cover which coincided with increased NO3 and plankton concentrations and decreased water clarity. However, as Chara cover increased, we observed a coincident decrease in nitrogen and increase in water clarity. The long-term goal of this research is to develop near-term iterative models that will use Chara cover and nutrient concentrations to predict water clarity and plankton biomass in this lagoon.
