Increasing levels of canopy cover (shading) over ponds is associated with a decline in the species diversity in ponds for many groups of aquatic insects. It is critical to understand the processes driving this pattern because the abandonment of small scale farms has resulted in the growth of dense secondary forests in portions of the Northeast and the upper Midwest of North America. This research will develop an understanding of how changes in the terrestrial environment may alter aquatic communities and threaten some species’ persistence. We will use an experimental approach to test whether observed declines in diversity arise from habitat selection behaviour (i.e. insects choosing not to colonize these sites) or from conditions that limit the growth and survivorship of insects colonizing these sites.
Additional Scientific Information
We will use an experimental array of 30, 378L mesocosms (cattle tanks) that are shaded to varying levels using shade cloth canopies and natural vegetation to assess how canopy cover affects arrival and colonization in these tanks. Tanks will be monitored for aquatic insects arriving at and colonizing these sites. In order to test how local conditions act as a filter on species persistence in these sites, we will also use experimental cages within these tanks to determine the growth and survival of larval dragonflies across this gradient of habitat conditions. These data will contribute to our understanding of how habitat selection and species sorting mechanisms act to structure these communities in the context of a wide-spread environmental change.
Principal Investigator: Shannon McCauley
Researcher(s): Sarah Glover