Rates of natural and anthropogenic change in shoreline habitats in the Kingston Basin, Lake Ontario

Shoreline habitats in the Kingston Basin have experienced continual change on a wide range of time scales, as a result of physical, chemical, and biotic stresses of both natural and anthropogenic origin. Not all change can or should be controlled. From a management perspective, stresses can be usefully subdivided into those that originate from the lake as a whole (e.g., water-level and-chemistry changes, introduction of exotic species) and those originating from the adjacent land area (e.g., point-source contamination and sedimentation). Stresses from the lake cannot be controlled locally, whereas those arising from terrestrial activities are more easily managed. Slow rates of change are less likely to have dramatic effects than rapid change, but a small change can have catastrophic effects if it exceeds the threshold tolerance of an ecosystem. Dramatic alterations to the entire ecosystem can also occur if a single, important species (e.g., a macrophyte) is adversely affected, because of complex feedback responses between the various components of the system. Thus, management strategies should focus on those areas that are particularly susceptible to land-based stress and on stresses that are most likely to exceed the tolerance of key components of an ecosystem.