Multiple excitation fluorometer for in situ oceanographic applications

Area of Science:

• Oceanography
• Marine Biology
• Biogeochemistry

Background:

• Accurate measurement of oceanic photosynthetic pigments is crucial for understanding marine primary productivity.
• Existing methods for in situ pigment detection face limitations in spectral resolution and discrimination capabilities.
• Developing advanced instrumentation is essential for real-time monitoring of phytoplankton dynamics.

Purpose of the Study:

• To describe a new in situ fluorometer designed for detecting oceanic photosynthetic pigment fluorescence.
• To evaluate the instrument's capability in discriminating between different algal species.
• To demonstrate the feasibility of its application in long-term oceanic deployments.

Main Methods:

• Development of an in situ fluorometer capable of recording emission spectra (546–733 nm) using three visible excitation bands at 10 Hz.
• Utilization of a Spectralon cell to enhance excitation coupling and sample collection efficiency.
• Deployment of the instrument on an undulating vehicle (SeaSoar) for at-sea data collection.

Main Results:

• The fluorometer successfully recorded fluorescence emission spectra in situ.
• Laboratory tests confirmed that fluorescence spectra from violet, blue, and green excitation effectively discriminate between various algal species.
• The instrument demonstrated reliable performance during extended in situ deployments on the SeaSoar vehicle.

Conclusions:

• The new in situ fluorometer is a capable tool for detecting oceanic photosynthetic pigment fluorescence.
• Spectral analysis of fluorescence provides a robust method for discriminating algal species in marine environments.
• The instrument's successful deployment signifies advancements in in situ oceanic monitoring technologies.