FIRE, Fluorescence Induction and Relaxation

FIRE, Fluorescence Induction and Relaxation

An incredibly useful and state of the art science tool in our ocean pasture stewards tool kit is our FIRE instrument. They don’t come cheap, way of the far side of $50,000 but an important piece of scientific equipment we purchased and made use of this year for very sophisticated fluorometry. Known as a Fluorescence Induction and Relaxation system or FIRe.  It is used to measure variable chlorophyll fluorescence in photosynthetic organisms, both Cyanobacters and Green phytoplankton. It’s the Green Gold Standard!

One of the Haida Village Project people using the FIRE instrument in the ships dry lab.

One of the Haida Village Project people using the FIRE instrument in the ships dry lab.

Over the course of our village ocean pasture project we made many hundred measurements with the FIRe instrument using samples we collected from the surface to great depths at all times of the day and night.

The FIRe was just one of 6 different fluorometers that were in near continuous use during the project. Collectively they yielded a treasure trove of data both inside our mesoscale ocean eddy as an incredible hourly time series over months watching an eddy go from a blue desert into a fabulous ocean Garden of Eden.

As far as we know this is the very first time in ocean history such a detailed study of ocean phyto-plankton has ever been done. Naturally we also have fantastic matching data from the world’s orbiting satellites courtesy of the the help from colleagues at the Canadian Space Agency and sister agencies around the world.

How does the FIRe System differ from Pulse Amplitude Modulated (PAM) fluorometer?

The FIRe System measures changes in chlorophyll fluorescence that occur during a short (100 – 400 μs) but intense (> 20,000 μmol photons m-2 s-1) flash of light whereas the PAM approach measures the fluorescence induced by a weak modulated light source while using ‘saturating’ pulses of ~3000 – 10,000 μmol photons m-2 s-1 to modify fluorescence yields.


FIRE Spectrometer

The FIRe System also fundamentally differs from a PAM in that the FIRe fully reduces the primary electron acceptor, QA, allowing a simultaneous single closure (STF) event of all photosystem II (PSII) reaction centers whereas the PAM technique generates multiple photochemical charge separations (MTF) that fully reduces QA, the secondary acceptor, QB, and plastoquinone (PQ). By lengthening the measuring protocol the FIRe can also yield MTF data.

For a complete discussion on the mechanistic and practical differences between the two techniques see: Suggett, D.J., K. Oxborough, N.R. Baker, H.L. MacIntyre, T.M. Kana, & R.J. Geider. 2003. Fast repetition rate and pulse amplitude modulation chlorophyll a fluorescence measurements for assessment of photosynthesis electron transport in marine phytoplankton. European Journal of Phycology. 38: 371-84.

Sato-Takabe, Y., K. Hamasaki, and K. Suzuki (2014) Photosynthetic competence of the marine aerobic an oxygenic phototrophic bacterium Roseobacter sp. under organic substrate limitation. Microb. Environ 29 100-103 doi:doi: 10.1264/jsme2.ME13130.

Sugie, K., H. Endo, K. Suzuki, J. Nishioka, H. Kiyosawa, and T. Yoshimura (2014) Synergistic effects of pCO2 and iron availability on nutrient consumption ratio of the Bering Sea phytoplankton community. Biogoesciences 10 6309-6321 doi:doi: 10.5194/bg-10-6309-2013.
Sato-Takabe, Y., K. Hamasaki, and K. Suzuki (2013) Photosynthetic characteristics of aerobic anoxygenic phototrophic bacteria Roseobacter and Erythrobacter strains Archiv. Microbiol. 194 331-341

Levy O., Bubinsky Z., Schneider K., Achituv Y., Zakai D., Gorbunov, M. (2004) Diurnal hysteresis in coral photosynthesis. Marine Ecology Progressive Series, 268 105-117

Gorbunov, M.Y., Kolber Z.S.,Falkowski, P.G. (1999) Measuring photosynthetic parameters in individual algal cells by Fast Repetition Rate fluorometry. Photosynthesis Research 2: 141-153
Takao, S., T. Hirawake, G. Hashida, H. Sasaki, H. Hattori, and K. Suzuki (0000) Phytoplankton community composition and photosynthetic physiology in the Australian Sector of the Southern Ocean during austral summer 2010/2011 Polar Biol. (submitted)