THERMAL STRUCTURE OF THE WATER COLUMN CONTROLS FREE-LIVING AND PARTICLE-ASSOCIATED PROKARYOTIC COMMUNITIES IN THE LAURENTIAN GREAT LAKES

The range of biogeochemical gradients in the Laurentian Great Lakes, in addition to the Lakes’ rapid warming, make the system a natural laboratory for studying microbial biogeography under climate change. Here we present an eight year timeseries of 16S rRNA sequencing from both free-living and particle-attached prokaryotic communities, collected across the five Great Lakes during episodic spring and summer sampling - totalling over 1600 samples. We find that water strata associated with thermal stratification harbor distinct microbial communities, even in conditions of inverse stratification where the strata differ in temperature by only ~2 degrees. Additionally, water temperature is one of the main drivers of community composition variance between strata. The free-living community is less diverse than the particle-associated community and more sensitive to environmental change. By contrast, individual taxa in the particle associated community have stronger relationships with temperature than those in the free-living size fraction. Overall, the structure of the prokaryotic community, the environmental drivers, and the effect of those drivers differ between size fractions. Together, our results demonstrate the effect of temperature on the community structure of prokaryotes in the Great Lakes and quantify year-to-year variability over 8 years. This baseline understanding is critical for detecting future changes and trends driven by ongoing warming.

Primary Presenter: Maria Hernandez Limon, University of Chicago (maria_hernandez@alumni.brown.edu)

Authors:

Maria Hernandez Limon, University of Chicago  (maria_hernandez@alumni.brown.edu)

Justin Podowski, Argonne National Lab  (jpodowski@anl.gov)

Sara Paver, University of Chicago  (sara.paver@gmail.com)

Maureen Coleman, University of Chicago  (mlcoleman@uchicago.edu)