Derek K. Gray |
My research Interests fall into three main categories:
|
|
|
Impacts of environmental change on aquatic communities
|
|
Understanding the factors that influence community responses to environmental stressors
Environmental change may lead to turnover in communities as resident species are replaced by those that have physiological tolerances better suited to the altered environment. However, past studies suggest that it is difficult to predict the trajectory of community change due to the constraints imposed by ecological and evolutionary forces. To improve our ability to predict community change it is necessary to understand the ecological and evolutionary forces at play as communities respond to stressors. In other words, we need to understand why communities respond the way they do to environmental change. Anthropogenic acidification is one of the best-studied stressors affecting aquatic ecosystems, making it an ideal case for examining the factors that influence community responses to environmental change. Industrial emissions of sulpher dioxide and nitrogen oxides caused the acidification of thousands of lakes in eastern North America and Europe. As lake water pH levels dropped in many Boreal Shield lakes, acid-sensitive zooplankton and fish species were lost. Although emissions reductions have occurred during the last three decades, aquatic communities are still in the process of recovering from this disturbance. I have conducted extensive work with acid-damaged zooplankton communities in lakes located on the north shore of Lake Huron in Killarney Provincial Park, Ontario. As pH levels have increased in these lakes there is evidence that acid-sensitive species are attempting to recolonize. Unfortunately, community recovery has occurred at a rate much slower than expected based on documented pH increases. My work has focused on elucidating the factors that may be slowing community responses to increasing pH levels. I have used two approaches: (1) field experimentation to determine which variables impact the probability of recolonization of damaged lakes by acid-sensitive species; and (2) modeling and statistical analyses to determine the factors that drive variation in zooplankton communities across the landscape. |