FastOcean APD Profiling System for in situ estimation of Gross Primary Productivity (GPP)

FastOcean APD Profiling System for in situ estimation of Gross Primary Productivity (GPP)

Fast Repetition Rate (FRR) fluorometry provides a non-intrusive and non-destructive method for probing photosynthesis by phytoplankton. The two FRR fluorometers within the FastOcean Ambient Plus Dark (APD) profiling system generate the data required to estimate the electron flux through all photosystem II (PSII) reaction centres per unit volume of sea water, on wide spatial and temporal scales. Given that Gross Primary Productivity by phytoplankton (GPP) is generally the main sink for PSII electron flux, these data can be used to estimate GPP. When the APD system is not being used for profiling, one or both of the FastOcean sensors can quickly be removed from the frame and coupled with one or two Act2 laboratory systems (see separate brochure).

 

The combination of FastOcean and Act2 allows fully automated fluorescence light curves (FLCs) to be run on discrete samples collected in the field or phytoplankton cultures.

 

 

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Benefits

  • Smaller, lighter and more flexible in operation than previous generations, while retaining a 600 m depth rating and robust construction
  • Three excitation wavelengths (centred at 450, 530 and 624 nm) for improved assessments of community structure and estimation of Gross Primary Productivity (GPP)
  • Extensive PC-based software for sensor programming, real time automated sensor control and real time data acquisition, analysis and archiving

Features

  • Full real time operation through a cable connection of up to 200 m or completely autonomous operation using battery power and internal data logging
  • Ambient and dark-adapted data can be synchronised and combined with PAR values to generate estimates of PSII electron flux per unit volume of sea water
  • A single FastOcean sensor can also be integrated with the Act2 laboratory system to generate fluorescence light curves (FLCs) from cultures or static samples collected in the field

Introduction

Fast Repetition Rate (FRR) fluorometry provides a non-intrusive and non-destructive method for probing photosynthesis by phytoplankton. The two FRR fluorometers within the FastOcean Ambient Plus Dark (APD) profiling system generate the data required to estimate the electron flux through all photosystem II (PSII) reaction centres per unit volume of sea water, on wide spatial and temporal scales.

 

Given that Gross Primary Productivity by phytoplankton (GPP) is generally the main sink for PSII electron flux, these data can be used to estimate GPP. When the APD system is not being used for profiling, one or both of the FastOcean sensors can quickly be removed from the frame and coupled with one or two Act2 laboratory systems (see separate brochure). The combination of FastOcean and Act2 allows fully automated fluorescence light curves (FLCs) to be run on discrete samples collected in the field or phytoplankton cultures. The FastOcean APD Profilling System is available from Chelsea Technologies Group Ltd.

How does it work?

The FastOcean sensors incorporated within the APD profiling system are Fast Repetition Rate fluorometers running in single turnover mode. Each measurement sequence is between 200 μs and 2.5 ms with a 40 to 100 ms interval between sequences. The system can be programmed to run single excitation LED combination or loop through two or more different combinations. 

 

Within the supplied FastPro8 software package, analysis of primary FRRf data is based on the equations provided by Kolber et al. (1998 - Biochim. Biophys. Acta 1367:88-106), while secondary analysis of FRRf data is based on the absorption method described by Oxborough et al. (2012 – Limnol. Oceanogr.: Methods 10:142-154). 

 

Estimation of GPP from FRR data is through the JVPII parameter, which is calculated as the product of the absorption coefficient for PSII light harvesting (derived rom the dark FRR data), the efficiency of PSII photochemistry (derived from the ambient FRR data) and photon irradiance (from the included PAR sensor). JVPII provides an estimate of the electron flux through all PSII reaction centres per unit volume. Derivation of a GPP is simply the value of JVPII divided by the number of electrons required to fix each carbon.

 

Data from the Dark and Ambient sensors within an APD system can easily be combined using tools incorporated within the FastPro8 software package.

Data from the Dark and Ambient sensors within an APD system can easily be combined using tools incorporated within the FastPro8 software package.


Parameters available

A wide range of fluorescence parameters are calculated by FastPro8, including:

  • The absorption cross section of PSII photochemistry (σPII)
  • Absorption coefficient of PSII light harvesting (aLHII)
  • Electron flux through PSII per unit volume (JVPII)
  • PSII photochemical efficiency
  • Photosystem II reaction centre concentration [RCII]

Configurations

The FastOcean APD profiling system can be supplied in real time or battery configurations.

 

  • The real time configuration is generally supplied with a profiling cable of up to 200 m in length. This cable allows for real time data acquisition and system control through a PC running our FastPro8 software.
  • With the battery configuration, data are logged within each FastOcean sensor. Data files are then downloaded through a USB port and processed using the FastPro8 software package.
  • Both configurations include a 0 – 60 bar pressure sensor and a PAR sensor. Data from both sensors are logged by the ambient FastOcean sensor with each FRR acquisition. 
  • Both FastOcean sensors within the APD system are suitable for combining with our laboratory-based Act2 system for running fully automated fluorescence light curves (see separate brochure).

Specification

FastOcean Sensor and APD System

  Details
Excitation LED channels

3 x 6 custom-made LEDs, centred at 450, 530 and 624 nm.

LED filtering

630 nm short-pass filter (>OD6 between 655 and 750 nm)

Signal detection

NIR-enhanced PMT with stabilised power supply 

Detection filtering

2 x 3 mm RG665 glass filters plus 682 nm, 30 nm half bandwidth interference filter 

Dynamic range

16-bit ADC provides an effective 15-bit range at each PMT eht setting.
The total dynamic range is at least five orders of magnitude 

Pressure and PAR

16-bit ADC for pressure sensor and 2π PAR sensor.
FastPro8 converts ADC output to dbar and µmol photons m-2 s-1, respectively 

Power requirements

18 to 36 VDC operating range. Protected to 72 VDC. 4.8 W continuous, 5 W peak 

Operating ambient temperature

-10 to 50°C 

External dimensions of FastOcean sensor

88 x 284 mm (diameter x length) excluding connectors 

External dimensions of APD system

316 x 292 x 685 mm (width x depth x height) 

Mass (weight in air, water) of FastOcean sensor

2.9 kg (28 N, 10 N) 

Mass (weight in air, water) of APD system

20.3 kg (200 N, 98 N) 

In view of our continual improvement, the designs and specifications of our products may vary from those described.

Downloads

Need more information?
Download FastOcean APD datasheet

 

Fast Repitition Rate Fluorometry in the Press:

 

Sophie Richier, Anna I. Macey, Nicola J. Pratt, David J. Honey, C. Mark Moore, Thomas S. Bibby, Ocean and Earth Science, National Oceanography Centre.  Abundances of Iron-Binding Photosynthetic and Nitrogen-Fixing Proteins of Trichodesmium Both in Culture and In Situ from the North AtlanticPlus One - 2012.   Download article pdf.

 

Oxborough, K. Moore, C.M., Suggett, D.J., Lawson, T., Chan, H.G. and Geider, R.G.   Direct estimation of functional PSII reaction centre concentration and PSII electron flux on a volume basis: a new approach to the analysis of Fast Repetition Rate fluorometry (FRRf) data. Liminology & Oceanography: Methods – 2012, 10:142-154. Link to article. Download pdf.