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 graph (Figure 6) displays yields determined at each station. Phytoplankton samples comprised of mainly diatoms and dinoflagellates.

Center for Integrated Marine Technologies (CIMT) Ocean Observing System Monterey, California

The PhytoFlash was integrated into the CIMT CTD January 2006 shipboard survey (Map 2). Water samples were collected with Niskin bottles and processed for extracted chlorophyll a. Figure 7 displays data reflecting the correlation between Fo and Fm with extracted chlorophyll a. Calculated minimum detection limits (MDL) were 0.15 µg/l. MDL calculations were similar for Fo and Fm, suggesting yields are accurate at low chlorophyll a concentrations.

Coastal Ocean Projects Program/River Influences on Shelf Ecosystems Columbia River, Oregon/Washington

The PhytoFlash was deployed as part of the NSF sponsored RISE program off the Oregon/Washington coast (Figure 8). Samples were collected from Niskin bottles, dark adapted for 30 minutes, and then run in laboratory mode. As expected there was a decrease in Fv/Fm moving from onshore to offshore, and from surface to depth.

CONCLUSIONS

• The PhytoFlash is able to produce repeatable physiological parameters for freshwater and marine phytoplankton at low concentrations.

• The PhytoFlash is the first in situ, solid-state active fluorometer for use in natural waters.

• The PhytoFlash can be used for real-time data collection through the use of the internal data logger and battery pack or integrated into a CTD system.

• The PhytoFlash makes real-time, variable fluorescence measurements a reality for the research community.

Acknowledgements

We would like to thank Dr. Raphael M. Kudela and Atma Roberts from the University of California at Santa Cruz, Dr. Erik Smith and Tracy Buck from the University of South Carolina's Belle W. Baruch Institute for Marine and Coastal Sciences, Dr. Nick Welschmeyer from Moss Landing Marine Laboratories and his graduate students, Dr. Jacco Kromkamp from the Netherlands Institute of Ecology (NIOO-KNAW), and the USGS crew at Menlo Park, California.

Author: Dr. Raphael Kudela, Tara Schraga, Chelsea Donovan

Institution: University of California Santa Cruz, USGS - Menlo Park, Turner Designs

Location: California, USA