1.-Experiment The experimental design consisted of 21 populations inoculated with 1 mL water samples taken near the Cedar Bog Lake dock on July 7th. Each population consisted of a final volume of 39 mL in transparent Greiner Bio-One vented-cap culture flasks. We used a three-by-two factorial design with three nitrogen concentrations (standard BG11 medium (17.6 mM NaNO3), a reduced nitrogen BG11 medium (9 mM NaNO3), and a BG11-0 medium (without nitrogen)) and (10 mM NaCl) and without NaCl addition. To account for the effect of nutrient addition, we added a control treatment with deionized water. Three replicates population of each experimental condition were stabilized. The experiment was run for 3 weeks. Table 1: Experimental design. dH20 BG11 BG11 reduce Nitrogen B11 without Nitrogen BG11 +NaCl BG11 reduce Nitrogen +NaCl B11 without Nitrogen+NaCl R1 R16 R10 R4 R19 R13 R7 R2 R17 R11 R5 R20 R14 R8 R3 R18 R12 R6 R21 R15 R9 1.1 FlowCam( Fluid Imaging Technologies) Data collection 0.15 mL aliquots of each population at week three were run through a Flowcam cytometer (Fluid Imaging Technologies) at a speed of 0.14 mL/min and collect images of individual particles and estimate biovolume using total area. The 10x magnification setting was used with a calibration factor of 0.5525. For each sample, the first 1,000 images taken by FlowCam were selected for species diversity analysis. Each folder is a separate population at T3 (21 days). It contains the original run (pictures and files) and within it can be found the classification by “groups” (pictures and files). 1.2 Flotation Device Technical Description Flotation Device is a suspension system to safely maintain planktonic microbial populations to carry out studies at the water temperature and light conditions of a water body. 1.3 Bradford Protein Assay Data Populations were checked weekly by sampling aliquots of all the populations and running Bradford Protein Assays as a proxy for population growth.

This material is based upon work supported by the Minnesota Agricultural Experiment Station, and the National Institute of Food and Agriculture, U.S. Department of Agriculture, project MIN-73-015 under accession no. 1009904 BBC was supported by the MNDrive environment grant entitled: Cyanotoxin Bioremediation with Microbes