Performance Data and In Situ Experimentation with the PhytoFlash a Submersible Active Fluorometer

Parameters: Active Fluorescence

Turner Designs, Inc has developed an in situ variable fluorescence system that can be used to determine the quantum efficiency of phytoplankton in both oligotrophic and mesotrophic environments. The PhytoFlash (patent pending) is distinct from other 'active' fluorometers on the market in that it is the first solid-state instrument capable of variable fluorescence measurements on natural concentrations of phytoplankton. The solid-state platform allows for a much wider range of uses due to the small size, power efficiency, more stable components, and lower price point.

The PhytoFlash can be integrated into a CTD or multi-parameter system, used in self-contained mode in conjunction with the internal data logger and attachable battery or in flow-through mode for laboratory work and in underway monitoring mode. The variable fluorescence measurement is being used in an ever-growing list of applications, such as;

• In situ measurement of phytoplankton photosynthetic parameters • Indicator of nutrient status of planktonic algae • Detection of the onset of algae blooms • Accurate measurement of algal biomass and monitoring algal community changes • Measurement of non-photochemical quenching (laboratory mode) • Ballast water monitoring

The PhytoFlash technique utilizes 3 low intensity LEDs to measure Fo and Fm and 6 high intensity LEDs to saturate cells in the sample chamber. The response curve from the saturating flash can be viewed in the laboratory mode. Unlike other 'active' fluorescence systems, the PhytoFlash does not provide induction curve data and is not designed as a physiological instrument for laboratory use. Rather, it is designed as a simplified and robust variable fluorescence system for submersible and/or laboratory use.

Phytoflash Specifications

Optical Specifications Excitation Filter: <500 nm Emission Filter: 680AF80 nm LED wavelength: 460nm Minimum Detection Limit: 0.15 µg/l

Electronic Specifications Sampling Rate: 0.2 Hz Saturating LED duration: 200-10,000 ms, 200ms (default) Data Format: RS-232

Physical Dimensions Length: 12 inches 30.5 cm Width: 3 inches 7.6 cm Weight (in air): 2.95 pounds 1.34 kg Sample Volume: 5.36 ml

PhytoFlash Parameters The PhytoFlash will provide the following parameters: Fo Minimum fluorescence Fm Maximum fluorescence Fv Variable fluorescence (Fm-Fo) Fv/Fm (yield) Maximum quantum yield of photochemistry in PSII Blank Calculated blank value used in calibration Response Curves Available during laboratory mode

Response curves (Figure 1) and physiological parameters (Table 1) of Dunaliella salina and Skeletonema were determined using the Blue PhytoFlash.

Comparison Testing

Figure 2. Yield comparisons of the diatom Thalassiosira weissflogii utilizing the fluorometric DCMU herbicide technique and the Turner Designs PhytoFlash Active Fluorometer (n=4).

Figure 3. Comparison of Turner Designs PhytoFlash submersible active fluorometer and the Walz PAM benchtop active fluorometer using green algae (Dunaliella) cultures at different concentrations.

Figure 4. Comparison of Turner Designs PhytoFlash and Chelsea’s Fast Tracka I during combined profiles in Monterey Bay.

In Situ Experiments

United States Geological Survey South Bay Cruise in San Francisco Bay, California

Samples were collected at five sites (Map 1) during CTD profiles along a northern transect and tested on the PhytoFlash. The first graph (Figure 5) presents a direct correlation between the Fo and extracted chlorophyll a. The second