Acoustic Instruments

Acoustical Ocean Ecology Group

Scientist Kelly Benoit-Bird and Research Technician Chad Waluk inspect the housing of an echosounder. Photo: Todd Walsh © 2017 MBARI

To see entire pelagic communities in the open sea, the Acoustical Ocean Ecology Group uses an instrument known as an echosounder. These instruments emit several sound frequencies from tens of kilohertz up to several megahertz from transducers, a device that serves as both an underwater speaker and a microphone. When these different frequencies reach organisms, they are either absorbed or reflected back to the transducer. Depending on how these sound waves are returned to us, we can determine the type of organisms present. The swim bladder of a fish, for example, reflects sound at a wide range of frequencies —therefore returning more of a signal to a transducer—than the chitinous body of krill which only reflects at relatively high frequencies.

The R/V Paragon’s Echosounder

Mechanical Engineer stands by the R/V Paragon’s echosounder. Photo: Emma Bueren © MBARI 2017

The R/V Paragon is the smallest vessel used by MBARI and is the least expensive to use for short trips studying Monterey Bay. The echosounder’s transducers point directly downward, enabling us to map the ocean vertically from the surface to approximately 1,000 meters depth.

The ROV Ventana’s Echosounder

Chief Engineer Mark Aiello assists with bringing in ROV Ventana. Photo: Emma Bueren © MBARI 2017

The remotely operated vehicle (ROV) Ventana is deployed off of the R/V Rachel Carson. We have integrated two echsounders with the vehicle’s science camera, allowing us to collect broadband acoustic data and video information simultaneously to a depth of 1,500 meters. These echosounders are pointed in the same direction as the camera, allowing us to get a clearer understanding of a specific layer in the ocean. Because of the rapid attenuation of light underwater, Ventana’s camera has a much shorter reach than our acoustic samples. However, we use the echosounder and the camera in conjunction because pelagic animals are not yet identifiable by their acoustic signatures alone. By comparing acoustic data to the animals that can be visually identified with Ventana’s camera, we are correlating acoustic responses to specific organisms. This allows us to work towards refining our ability to classify animals in natural settings.

The Deep Ocean REMUS Echosounder 

 The Deep Ocean REMUS Echosounder (DOR-E). Image courtesy Kelly Benoit-Bird

The Deep Ocean REMUS Echosounder (DOR-E) is an AUV with two split-beam echosounders at 38 kilohertz and 120 kilohertz. It is capable of traveling to depths up to 600 meters and has a battery life of approximately 20 hours, allowing the Acoustical Ocean Ecology lab to get almost an entire day’s cycle of acoustic information from animals living in the deep sea. This is useful for understanding the daily cycles and behaviors of pelagic organisms.

How does the presence of technology affect the behaviors of creatures? 

Additionally, we are interested in how the presence of observational tools like ROVs impact the behaviors of pelagic organisms. On one field expedition, we identified an aggregation of animals approximately 60 meters ahead of the ROV—and out of the camera’s view. This large group of animals remained consistently 60 meters away until the lights of the ROV were turned off, which allowed us to approach. However, turning the lights back on caused the organisms to quickly swim away. The camera was only able to catch a glimpse of fins before the organisms, revealed as some sort of fish, were gone. With the ROV alone, the nearby school of fish would never have been discovered.

Science

Upper-ocean systems
Acoustical ocean ecology
Acoustic instruments
Acoustic fingerprinting
Acoustic community ecology
Acoustics in the news
Biological oceanography
Global modes of sea surface temperature
Nitrate supply estimates in upwelling systems
Chemical sensors
Chemical data
Land/Ocean Biogeochemical Observatory in Elkhorn Slough
Listing of floats
SOCCOM float visualization
Periodic table of elements in the ocean
Biogeochemical-Argo Report
Profiling float
Marine microbes
Population dynamics of phytoplankton
Microbial predators
Microbe-algae interactions
Targeted metagenomics
In the news
Upcoming events and lab news
Past talks and presentations
Join the lab
Resources
Molecular ecology
Molecular systematics
SIMZ Project
Bone-eating worms
Gene flow and dispersal
Molecular-ecology expeditions
Interdisciplinary field experiments
Ecogenomic Sensing
Genomic sensors
Field experiments
Harmful algal blooms (HABs)
Water quality
Environmental Sample Processor
ESP Web Portal
In the news
Ocean observing system
Midwater research
Midwater ecology
Deep-sea squids and octopuses
Food web dynamics
Midwater time series
Respiration studies
Zooplankton biodiversity
Seafloor processes
Biology and ecology
Effects of humans
Ocean acidification, warming, deoxygenation
Lost shipping container study
Effects of upwelling
Faunal patterns
Past research
Technology development
High-CO2 / low-pH ocean
Benthic respirometer system
Climate change in extreme environments
Monitoring instrumentation suite
Sargasso Sea research
Antarctic research
Long-term time series
Geological changes
Arctic Shelf Edge
Continental Margins and Canyon Dynamics
Coordinated Canyon Experiment
Monterey Canyon: Stunning deep-sea topography revealed
Ocean chemistry of greenhouse gases
Emerging science of a high CO2/low pH ocean
Submarine volcanoes
Mid-ocean ridges
Magmatic processes
Volcanic processes
Explosive eruptions
Hydrothermal systems
Back arc spreading ridges
Seamounts
Near-ridge seamounts
Continental margin seamounts
Non-hot-spot linear chains
Eclectic seamounts topics
Margin processes
Hydrates and seeps
California borderland
Hot spot research
Hot-spot plumes
Magmatic processes
Volcanic processes
Explosive eruptions
Landslides
Volcanic hazards
Hydrothermal systems
Flexural arch
Coral reefs
ReefGrow software
Biogeography
Eclectic topics
Submarine volcanism cruises
Volcanoes resources
Areas of study
Biology
Microscopic biology research
Open ocean biology research
Seafloor biology research
Chemistry
Automated chemical sensors
Methane in the seafloor
Geology
Volcanoes and seamounts
Hydrothermal vents
Methane in the seafloor
Submarine canyons
Earthquakes and landslides
Ocean acidification
Physical oceanography and climate change
Ocean circulation and algal blooms
Ocean cycles and climate change
Research publications