Research

 

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Main Research Interests:

Ecology of littoral areas in lakes: Spatial and temporal distribution of  habitats and benthic communities.

Foodwebs: Feeding interactions in planktonic and benthic communities, especially between invertebrates and algae.

Macroecology: Body size distribution, Allometric relationships, Scaling of environmental variability.

 

Current Projects:

1. Distribution and dynamics of foodwebs in the littoral zone of lakes

The shallow littoral areas in lakes support the most productive and diverse biological communities, and because of their proximity to shore, they are potentially the most vulnerable to changes in the watershed (e.g. fire, logging, urban development), and in direct and indirect effects of climate changes (e.g., water levels, thermal structure and transparency of lakes).  However, because these littoral communities are very patchy and dynamic, it is still extremely difficult to measure and predict their productivity, and to detect anything but the most dramatic impacts from natural or anthropogenic changes.  It is well known that winds and lake morphometry are important determinants of the thermal stratification and of water movements in lakes, and that hydrological forces affect the pattern and timing of sediment movements.  These forces set clear constraints on the characteristics of habitats that can be found in the littoral zone, which in turn should determine the distribution, composition and dynamics of biological communities.  We are studying the links between physical constraints, chemical composition of the sediments (nutrients, organic matter) and biological communities (algae and invertebrates) in the littoral areas in lakes.

 

2. Fueling the base of lake foodwebs: Internal nutrient loading in the littoral zone of lakes    (Collaborator: Dr. G.K. Nürnberg)

The sediments that cover the bottom of lakes are rich in nutrients that limit biological productivity in the overlying lake water.  The exchange of phosphorus between resuspended sediment particles and the surrounding water is well-described by sorption equilibrium models. This means that the phosphorus (P) exchange can go in both directions: resuspended sediments can either release P to water with low P concentrations (e.g. during the growing season), or strip P from water with high P concentrations (e.g. during lake turnover, from point sources). The release of phosphorus into warm, well-lit and biologically diverse shallow areas can directly enhance lake productivity during the summer months, and may be more important from an ecological perspective, than the well-known summer nutrient release in deep anoxic waters. In this project, we test the role of resuspended sediments in the internal loading of phosphorus to shallow littoral areas.

 

3. Structure and function of communities in variable environments  (Collaborator on some of this work: Dr. B.J. Shuter)

Recent theoretical models suggest that the scaling of environmental variability (i.e. the relative magnitude of variability at different time scales, or noise colour) can affect population dynamics and the probability of population extinction.  This in turn should have implications for the structure of communities.  We have several ongoing projects to: 1) quantify and compare the scaling of environmental variability in natural ecosystems, and 2) test experimentally the influence of the scaling of environmental variability on the structure and growth of natural algal communities in the littoral zone of lakes.