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An Introduction to DEIMOS

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Deepwater Echo Integrating Marine Observatory System

John Horne, David Barbee, and Dick Kreisberg

The Deepwater Echo Integrating Marine Observatory System, or DEIMOS, is an upward looking echo sounder package located at approximately 900 meters depth in Monterey Bay. DEIMOS is connected to the Monterey Bay Accelerated Research System, known as MARS. MARS is the testbed for scientific instruments as part of the National Science Foundation sponsored Ocean Observatories Initiative or OOI. MARS provides power and data transfer infrastructure for ocean observatory projects and is housed at the Monterey Bay Aquarium Research Institute in Moss Landing, California.

MARS overview
MARS and several instrument packages, including DEIMOS, are pictured near Monterey Canyon. The cable connecting the node to shore is over 50km long. Picture courtesy of MBARI.
© 2009 MBARI

As the graphic above shows, other instrument packages are being connected to MARS. Currently, an ultra-senstiive seismometer called MOBB is installed. MOBB is a University of California at Berkeley project. In coordination with land-based sensors throughout Northern and Central California, it monitors the San Andreas fault. Data collected by MOBB will eventually be available online at the Northern California Earthquake Data Center.

Other instrument packages are currently being developed for installation at MARS. See the MARS sensor page for a general description of the sensors which have been envisioned for the observatory.

3D model of Deimos
A 3D model of DEIMOS deployed at 900 meters depth in Monterey Bay, California. Image generated courtesy of Google Earth 5. Download the placemark or audio tour.

DEIMOS on the ROV sled
DEIMOS ready for deployment from the ROV Ventana sled. The Ventana carried the instrument to the seafloor and connected it to the MARS node.

Fisheries acoustic data are typically collected using a vessel-mounted echosounder while surveying long, straight transects. The data are used to estimate aquatic organism (zooplankton, fish) abundance and to study individual and group animal behaviors such as migration and schooling.

Spatial densities and distributions of fish and zooplankton change over time. Episodic factors, such as weather events, can dominate cyclic changes over short periods. Cyclic changes in density distributions arise from a variety of biological and physical factors operating over a range of temporal scales. Examples of cyclic scales are diel (daily), lunar (28 days), and annual (yearly).

DEIMOS provides a unique opportunity to examine distributions and fluxes of pelagic animals over long periods. Acoustic densities will be continuously collected over many months. The resulting data provide high resolution, long term measurements that are not typically available from acoustic research surveys. The ability to access the data in real time also provides the ability to monitor biological reactions to short term events, such as upwelling, that can be investigated immediately.

Data collected by DEIMOS
Acoustic density (Sv, dB re 1 m-1) over 42 hours from DEIMOS. 900 meters of the water column is displayed. A diel (daily) cycle can be seen where zooplankton and fish migrate toward the surface at night to feed or to avoid being eaten.

We have created a placemark in Google Earth to show where DEIMOS is located. The placemark includes a 3D model of the instrument. A second version of the placemark includes an audio tour of DEIMOS and a 3D model of ORCA's Eye-in-the-Sea optical instrument that is also connected to MARS. The files are created for the Google Earth 5 Desktop Application. We recommend turning on the "Ocean" layer.

Download the original .KMZ here.
Download the audio tour version here. (500kB)

Group Pictures
Aboard the RV Point Lobos prior to deployment.
From Right to Left: Dr. John Horne, DEIMOS and Ventana, David Barbee, and Dick Kreisberg.

This research was made possible by the University of Washington's School of Aquatic and Fishery Sciences, Kongsberg Simard, and the Monterey Bay Aquarium Research Institute.

©2010 Fisheries Acoustics Research