A multivariate approach for evaluating progress towards phytoplankton community restoration targets: Examples from eutrophication and acidification case histories

Abstract

Two disturbed aquatic systems, Bowland Lake, a strongly acidic lake (pH=4.9) in south-central Ontario, and the eutrophic Bay of Quinte at the northeastern end of Lake Ontario were selected as case histories for demonstration of an analytical protocol for defining and evaluating phytoplankton community rehabilitation targets. Bowland Lake was experimentally neutralized in 1983 to evaluate the efficacy of an application of a powdered limestone slurry for rehabilitating biological communities in the lake. The Bay of Quinte was identified by the International Joint Commission in 1985 as one of 42 ‘Areas of Concern’ in American and Canadian waters of the Great Lakes for which a Remedial Action Plan is required to restore beneficial uses. Phosphorus loading controls were implemented in the Bay of Quinte drainage basin in late 1977 to early 1978. In both cases, pre- and post-treatment phytoplankton community structure data were used to assess the degree of phytoplankton community impairment and the response to remediation by comparing the phytoplankton communities to those from suitable reference locations. The rationale, development and application of model phytoplankton communities intended to serve as ‘targets’ for phytoplankton community rehabilitation are presented within a multivariate framework of community structure. It is recommended that these, or similar analytical protocols based on multivariate methods for defining community structure, be more widely applied when corrective actions are taken to rehabilitate aquatic systems.