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Research Projects - Arjun Chennu

Research Themes

Marine Ecology

Photosynthesis in the cryptic micro-benthos

  • Mapping the in-situ microscale variability of microphytobenthos in coastal sediments
  • Non-invasive and quantiative monitoring of microphytobenthos dynamics
  • Rapid reactivation of desiccated cyanobacterial mats upon rehydration

Digitizing the coral reef

  • Development of new survey method for high-resolution mapping of reef substrata (see HyperDiver)
  • Automated mapping of reef substrata using underwater hyperspectral imaging and machine learning models.
  • Comparison of reef mapping methods
  • Habitat structure and spatial ecology of naturally-acidified coral reefs in Papua New Guinea
  • See:¬†press release & video
  • See publication.

Effect of macrofauna on microphytobenthos

  • The gardening lugworm: fertilizing effect of bio-irrigation by lugworms (Arenical marina) at depth on the surficial microalgal population
  • Modeling the transport of porewater and nutrients within sediments under bioadvective load

Phototrophy in the Arctic seas

  • Monitoring benthic phototrophs in the Arctic sea during the winter to spring transition
  • Long-term data collection through a remotely-operable underwater observatory
  • Photophysiology of cold-water phototrophs under light and nutrient stress using fluorometry

Method and Technology Development

HyperSub: submersible hyperspectral scanning system

  • A novel submersible instrument for hyperspectral imaging of the shallow benthos (75 m)
  • Design and construction of the hardware and control systems for autonomous operation
  • Used & tested on intertidal sandflats and in subtidal diver-assisted deployments

HyperDiver: diver-operated hyperspectral imager

  • A mobile underwater hyperspectral imager for diver-operated surveys of the benthos
  • Design and construction of the diver interface for measurements in open water
  • Field testing and operation of hyperdiver in coral reefs in Papua New Guinea
  • See publication

High-resolution mapping of microphytobenthos distribution

  • Millimeter-scale quantification of MPB biomass in surficial sediment using hyperspectral imaging
  • Effect of sediment grain-size on light-scattering and empirical calibration of spectral index
  • Modeling and tracing the diel vertical migration of microphytobenthos from the spectral signal
  • See publication here

Remotely-operable underwater instrumentation

  • Deployment of microprofiler on Wally the Crawler for interactive profiling in the deep sea network from NeptuneCanada
  • Development of software for remote or autonomous operation of devices (see SinKrafT)

Optical Physics & Spectroscopy

Hyperspectral Imaging

  • Collection of hyperspectral images in the field (intertidal or underwater), in laboratory or under microscopes
  • Analysis of hyperspectral data for spectral identification and quantification of photopigments
  • Experience in theory and experiment of spectral analysis for benthic photosynthesis and ecology

Programming and Modeling

  • Developed a software platform¬† for hardware interaction of devices distributed over a network
  • Unified interface to a modular architecture of devices, communicating over standard network protocols
  • Handles low-bandwidth devices (sensors, loggers, switches, motors) as well as high-bandwidth ones (imagers)
  • Detailed logging and error-correction options for field-based and autonomous operations
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