In situ plankton and fish detection based on optical gated sampling

Area of Science:

• Marine biology
• Optical engineering
• Biotechnology

Background:

• Traditional plankton and fish detection methods have limitations in sampling volume and spatial resolution.
• Optical cameras offer limited sampling volumes, while imaging sonar lacks species identification capabilities.
• Existing technologies struggle with detecting small or transparent marine organisms.

Purpose of the Study:

• To develop an in situ detection method for millimeter- to centimeter-scale plankton and fish.
• To overcome the limitations of fixed sampling volumes and low spatial resolution in current detection technologies.
• To enable flexible adjustment of sampling volume and enhance detection contrast for transparent organisms.

Main Methods:

• Proposed an in situ detection method using optical gated sampling.
• Adjusted sampling volume by synchronizing gate and illuminator laser pulses.
• Utilized gated sampling to suppress backscattering and filter background noise.
• Derived target abundance from the convolution of gate and laser pulses.

Main Results:

• Achieved flexible adjustment of sampling volume for diverse target sizes.
• Demonstrated high-contrast detection of transparent planktons.
• Obtained a spatial resolution better than 100 μm for transparent jellyfishes.
• Successfully demonstrated abundance measurement and sampling volume adjustment in experiments.

Conclusions:

• Optical gated sampling offers a flexible and high-resolution solution for in situ plankton and fish detection.
• The method effectively addresses challenges posed by small, transparent organisms and environmental noise.
• This technology has the potential to significantly advance marine ecological monitoring and research.