Bio-physical Coupling

Phytoplankton are responsible for almost half of the Earth’s primary production, they form the basis of most aquatic food webs, profoundly influence water Jarad deploying SCAMP quality and are sensitive to climate change. Phytoplankton readily respond to alterations inphysical forcing. Therefore, understanding the mechanisms of physical – biological coupling in lakes is crucial if we want to predict population and community dynamics of phytoplankton, including the occurrence of harmful algal blooms, at present and in the future.

We are carrying out an integrated field sampling program on Michigan lakes (near the Kellogg Biological Station) that differ in size, morphology and trophic status. The key measurements include high-resolution profiles of temperature, conductivity, pressure, irradiance, major nutrients and fluorescence. Simultaneously, we monitor phytoplankton depth distribution, taxonomic composition and size structure. The novelty of these measurements is that they provide a much more comprehensive and accurate picture of the highly dynamic physical processes in stratified lakes, including a detailed turbulence characterization (using SCAMP, Self-Contained Autonomous Micro Profiler), and determine phytoplankton responses to these processes.

Chlorophyll Profiles

Chlorophyll profiles over the season in Gull Lake. Note single and multiple deep chlorophyll maxima.

Our goals are to characterize the dominant physical processes in stratified lakes that are relevant to phytoplankton; quantify temporal and spatial scales of physical variability with an emphasis on fluctuations in nutrients and irradiance, assess the magnitude and frequency of fluctuations in nutrient and light fields and characterize phytoplankton responses at different organizational and temporal scales to dynamic nutrient fluxes and light climate during a stratified period.

This research will improve our understanding of the role of temporal and spatial heterogeneity in structuring ecological communities, mechanisms of physical-biological coupling in aquatic systems, and understanding how changes in physical forcing change primary productivity and community composition of phytoplankton.

Personnel

Lab Members

Elena Litchman, Jarad Mellard, Kohei Yoshiyama, Ally Hutchens and Pam Woodruff

Collaborators

Sally MacIntyre and Robyn Smyth (UCSB) and Phani Mantha (MSU)

Financial Suppport

Litchman, E., and P. Mantha. 2006-2007. Physical-biological coupling in the pelagic: the role of dynamic physical processes in structuring phytoplankton communities. MSU Center for Water Sciences venture grant.

Last updated: March 13, 2009