Science at the Center for Limnology:

Paul Hanson

To what extent do micro-strata in the surface waters of lakes influence the ecosystem processes that determine lake metabolism? The traditional model of a three-layered-lake does not take into account strata that develop in the surface waters during periods of high irradiance and low wind. These “micro-strata” can persist for hours, or even days, creating vertical heterogeneity that may affect physical, chemical, and biological conditions in the water column. How the physical and chemical conditions within the strata control biological process remains largely unexplored. Through high-frequency sampling by in-situ sensors, coupled with a field sampling program, we will observe the evolution of relevant variables at high frequency through time, and use these data to inform the development of coupled physical-chemical-biological models that address the metabolism question.

Steve Carpenter

Are major shifts in phytoplankton species dominance preceded by statistical shifts in time series, such as increased variance and other moments, increased autoregression coefficient, reddening of variance spectra? Theory indicates that such statistical changes should be leading indicators of big shifts in phytoplankton. To evaluate this hypothesis, we need data on chlorophyll and phycocyanin at sub-day frequence before, during and after major shifts in phytoplankton composition. Onset of the spring clearwater phase, breakdown of spring clearwater, onset of summer blue-green blooms, and the breakdown of stratification and onset of autumn blooms are times when these indicators could be tested.

Research Highlights

The CFL aquatic research organization is a founding member of the Global Lake Ecological Observatory Network (GLEON). Lake Mendota is one of the instrumented sites participating in the network, and data from it and other instrumented sites are available from the data section of GLEON’s web site.

Paul Hanson at the CFL is interested in integrating the high-resolution time series data from the buoy, spatial data from from MODIS overpasses, and data from manual sampling events into an easily accessible cyberinfrastructure. Web-based access to these data would make them easily retrievable by researchers both at the CFL and across the world, allowing them to focus on data analysis and answering their science questions. The research performed could provide valuable insight into the links between the hydrological and biological processes of the lake. These data would also be readily available to instructional programs to educate students from the elementary to graduate levels about lake ecology.


For a list of publications related to these kinds of data, please visit the products page of GLEON’S web site.