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Welcome to my lab!

Are you interested in research on phytoplankton productivity, phytoplankton ecology or marine productivity? Are you an undergraduate at FSU, a student looking for a Masters or PhD position? Please contact me via email!

In my lab we use a diverse set of instruments to control environmental parameters, measure the response of the phytoplankton cells to these parameters and identify limitations and trade-offs of these organisms based on investigating molecular and physiological processes which are key for determining the competitive ability of species.


Current projects:

CCE-LTER: In collaboration with Mike Stukel (FSU), Mark Ohman (SCRIPPS) and Nicolas Cassar (Duke), the Kranz lab was invited to measure Net Community Productivity during the 2017 CCE-LTER Process Cruise (P1706). We followed a freshly upwelled water column and ecosystem function across and along the filament which established. The Kranz group (only me at this time) measured net community productivity (NCP) using O2:Ar MIMS measurements. Local “hotspots” of high productivity could be measured across and along the filament and strong diurnal periodicity in NCP was detected in the high productive coastal areas.

CO2 effects in Karenia brevis: This study was the project of Tristyn Bercel (PhD student in the lab). Tristyn acclimated the dinoflagellate K. brevis to low, ambient and high CO2 concentrations and measured the response as well as underlying physiological mechanisms. The manuscript for this study is written and the paper will be submitted in June 2018. A follow-up project is currently started to disentangle pH / CO2 effects.


Effect of different growth lights on photophysiology and productivity in different phytoplankton functional groups. This project compares commercially available growth lights with different emission spectra (different light colors) and investigates the cellular response. This project was started by 2 UROP students is is currently wrapped up by Tristyn and Brooke.

NO3 isotopes and phytoplankton stress: We are interested in the nitrogen isotope effect of different phytoplankton species under distinct environmental conditions.

Measuring macrophyte C-acquisition: A new chamber for our MIMS system was developed and we are currently starting to characterize the carbon acquisition mechanisms of aquatic macrophytes (mainly seagrass) using this new system.

Lab equipment: 

  • Tools to culture phytoplankton cells:
    • CO2 gas mixing to generate different CO2 concentrations 1-2000ppm)
    • temperature controlled incubators and walk in temperature controlled room
    • different lighting systems (LED based and Arduino controlled, Fluorescent light bulbs, sunlight on rooftop)
    • Peristaltic pumps for continuous cultures
    • clean bench
  • Tools to measure and monitor phytoplankton growth and community composition
    • Microscope and counting cells
    • Fluorometer (Trilogy)
    • UV-Vis, Fluorescence, Luminescence -Multiple reader for ¬†measuring Chl a fluorescence, nutrient analysis
    • Coulter counter (Beckman-Z2)
    • Flow cytometer (Beckman)
    • Filtration units
    • UV-Vis spectrophotometer (1,5,10cm Quarz glass cells)
  • Tools to measure cell physiology and molecular mechanisms:
    • Aquapen
    • FRRF (Act2 Chelsea)
    • Membane Inlet Mass Spectrometer with cuvettes for flow through analysis, 8ml sample cuvette and macrophyte flow cell.
    • Optode system for O2 measurements
    • Western-Blot station
    • UV-Vis, Fluorescence, Luminescence -Multiple reader for ¬†measuring Chl a fluorescence, nutrient analysis
    • UV-Vis spectrophotometer (1,5,10cm Quarz glass cells)
    • GC for Acetylene reduction assay
    • radio isotope laboratory to measure 14 C
    • CO2 gas analyzer
  • General Lab equipment:
    • scales, water bath, heater plates, centrifuges, tool work bench, incubators, microwave, freezer, fridge, pipettes – if you made it to here you must be either bored or very interested in my lab… we have a lot more items used in the lab hidden in drawers.