Kenneth Fortino

research.summary

My lab's research focuses on the factors that control community structure and ecosystem function in lakes and streams.

Current Projects

Leaf litter decomposition in man-made ponds

Our current research is investigating the dynamics of leaf litter decomposition in man-made ponds in Virginia.

The Southeastern United States largely lacks natural lakes and ponds but man-made ponds are abundant and are the dominant lentic habitat in the region. Despite this we know very little about how organic matter is processed in man-made ponds and how these systems interact with to climate change and other human interactions with the environment.

Our research is currently investigating:

Photo of students on a lake in Farmville VA

Past Projects

The effect of funtional diversity on ecological function in a shallow man–made pond

The number of man-made ponds is increasing but the effect of these systems on carbon cycling remains poorly described. We investigated the relationship between functional diversity and ecological functioning in a shallow quarry pond near DePauw University, Indiana. The sediment macroinvertebrate community was dominated by chironomidae in two functional groups: predators (tanypodinae) and tube-building collectors (chironominae). To test if the functional diversity of the sediment community affected the functional properties of the sediment system we conducted laboratory mesocosm studies on sediment organic matter processing (measured as sediment oxygen demand; SOD), water column chlorophyll concentration, and water column bacterial abundance. We found that the presence of the collector functional group significantly elevated SOD, regardless of the presence of the predator. However the presence of the predator reduced the water column chlorophyll concentration and elevated bacterial abindance. These results suggest that the functional properties of shallow lake sediments is affected by the functional diversity of the macroivertebrate community, and that changes to macroinvertebrate diversity can have implications for how small ponds affect the carbon cycle.

photo of quarry pond sampling

Interactions between transparency and sediment oxygen demand in arctic lakes

The stratification depth of lakes is strongly affected by the transparency of the water. Our research on lakes in the Alaskan Arctic supports this previous finding. Using surveys of more than 30 lakes over 3 years we found that clear lakes have deeper epilimnia than stained lakes. Furthermore, we found that sediment oxygen demand (SOD) in these same lakes was proportional to the temperature and oxygen concentration of the water above the sediments. These findings indicate a connection between SOD and lake transparency, since the distribution of temperature and oxygen in stratified lakes is mainly controlled by the stratification depth. The epilimnetic waters are relatively warm and oxygenated and should support high SOD, while the hypolimnetic waters are relatively cold and hypoxic and should support relatively lower SOD.

Given that SOD is a measure of the rate of organic matter breakdown within the lake sediments, these results indicate that changes in lake temperature and transparency could affect sediment organic matter storage in these lakes. To evaluate this we modeled the effect of epilimnetic warming alone and epilimnetic warming combined with a reduction in lake transparency that is predicted to accompany climate change in the Arctic. Our results show that warming alone increased SOD and thus reduced organic matter storage in the lakes but that warming combined with a reduction in transparency reduced SOD due to the reduction in stratification depth and the concomitant reduction in the area of epilimnetic sediments.

photo of sampling an arctic lake with a van dorn sampler

publicly available data and analyses

Our lab is committed to open, repeatable science and all of our data and analyses are publicly available in the following resources:

Open Lab Notebook: provides continually updated documentation of the lab activities. The notebook is written for the use of the lab members but all content and data is publicly available and is licensed CC-BY.

GitHub Repositories: contain all of the lab data, code, and analysis.

Figshare: provides examples of presentable data and analyses in the form of figures, posters, and presentations.

publications

Manuscripts in Preparation