An integrated approach to identifying ecosystem recovery targets: Application to the Bay of Quinte

In 1985, the International Joint Commission identified the Bay of Quinte as an Area of Concern due to its degraded ecosystem. A Remediation Action Plan was established with delisting targets including the goals of decreasing phosphorous loading and restoring the upper (fish and wildlife) and lower (phytoplankton, zooplankton, and benthic invertebrates) trophic levels. We examined the consistency among seven Remedial Action Plan targets using Ecopath, a mass-balance model, for the upper Bay of Quinte for the post Zebra Mussel (Dreissena polymorpha) invasion period (1995–2002). We quantified the trophic consequences of bottom-up-control by gradually reducing the phytoplankton biomass until the Ecopath model became unbalanced (27% reduction). Replicate (n = 25) mass-balance solutions consistently showed that reductions in Zebra Mussel biomass were necessary to achieve mass-balance. This bottom-up control met the nutrient (total phosphorus), fish, benthic invertebrates, and phytoplankton population RAP targets. Based on these consistent results, it is recommended that future modelling efforts examine the effects of further phytoplankton biomass reductions.