Modeling Study of Phytoplankton Response in Lake Michigan to a Changing Climate

Climatic change is projected to significantly impact lake ecosystems by altering physical processes and biophysical dynamics. We applied a three-dimensional biophysical model to investigate the impacts of future climate scenarios on phytoplankton dynamics and primary production in Lake Michigan. With a storyline approach, we conducted both historical simulations for six representative years (2005, 2006, 2010, 2014, 2015, and 2016) and future projections for the mid-21st century (2040–2049) and late 21st century (2090–2099) under the high-emission Representative Concentration Pathway (RCP) 8.5 scenario. Our results indicate that changes in the lake’s thermal structure, transitioning from dimictic to monomictic mixing regimes, will alter seasonal phytoplankton patterns. The winter-spring phytoplankton blooms, characteristic of mid-depth (30–90 m) and offshore (>90 m) regions, are expected to disappear due to diminished winter stratification and reduced spring turnover. Late spring and early summer blooms are projected to shift earlier, driven by the earlier onset and extended duration of summer stratification. The deep chlorophyll layer is projected to develop 15–30 days earlier and last 20–45 days longer by the mid- and late-21st century. An overall increase in primary production was simulated, driven by rising water temperatures and increased photosynthetically active radiation, along with a significant shift in the seasonal patterns.

Presentation Preference: Oral

Primary Presenter: Mark Rowe, NOAA Great Lakes Environmental Research Laboratory (mark.rowe@noaa.gov)

Authors:

Xing Zhou, Michigan Technological University; currently at Georgia Institute of Technology  (xzhou473@gatech.edu)

Mark Rowe, NOAA Great Lakes Environmental Research Laboratory  (mark.rowe@noaa.gov)

Peter Alsip, NOAA Great Lakes Environmental Research Laboratory  (peter.alsip@noaa.gov)

David Bunnell, USGS Great Lakes Science Center  (dbunnell@usgs.gov)

Tomas Hook, Purdue University  (thook@purdue.edu)

Edward Rutherford, NOAA Great Lakes Environmental Research Laboratory  (ed.rutherford@noaa.gov)

Paris Collingsworth, Purdue University  (pcolling@purdue.edu)

Spencer Gardner, Purdue University  (gardn125@purdue.edu)

Pengfei Xue, Michigan Technological University  (pexue@mtu.edu)