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July 5, 2007

Armchair oceanography: Underwater photos beamed from local park via Internet

News and Information

Video clips of seals zipping around, a kelp crab latching onto the lens of the camera, swirling schools of silvery perch and even birds “swimming” by. Such images, brought via the Internet from a science node in Puget Sound off Seahurst Park in Burien, offer the experience of armchair oceanography, something that also may be possible one day in ocean waters 2 miles deep off the Washington coast.

Visit the Seahurst Observatory page at http://seahurst.apl.washington.edu/ and click on the “Video Highlights” for the best snippets taped using a motion-activated camera.

Check out the gnarly looking lion’s mane jellyfish among the clips on the first page. A harbor seal shows its stuff on the second. One hilarious time-lapse clip on the third page shows a sunflower starfish as it plops itself into a strawberry pot that researchers embedded in the sand as a point of reference for the videos. A number of different birds diving for fish have been caught on film, including a ruby-throated loon on page four.

The Seahurst Observatory Web site is a way for the scientists to share the surprises and fun while they conduct perfectly serious work on nodes and instruments destined for remote and harsh places on the seafloor, according to Bruce Howe, Tim McGinnis and Jason Gobat, researchers and engineers with the UW’s Applied Physics Laboratory.

On June 26 UW scientists plugged in a first-of-its-kind mooring that is being developed by the laboratory. The work anticipates a much tougher test next spring when the mooring is deployed in 2,800 feet of water in Monterey Bay, according to Howe, the principal investigator for that project, called ALOHA-MARS.

If successful, moorings similar to the one at Seahurst will one day be installed 2 miles deep in the ocean as part of a large, cabled ocean observatory being planned on the Juan de Fuca tectonic plate off the Washington and Oregon coast (see http://uwnews.washington.edu/ni/uweek/uweekarticle.asp?articleID=33691) as well as other locations around the world.

Existing saltwater intake pipes from a shoreside marine-biology labortory in Seahurst Park provided a conduit for wires to two nodes installed this spring on the bottom. One is in about 25 feet of water and one in about 100 feet. Each node is like a combination power strip and ethernet hub into which the scientists can plug various instruments and sensors.

The mooring installed during a long day of work June 26 is an 80-foot cable anchoring a buoy equipped with instruments to the bottom and connecting it to the node in 100 feet of water. One can see data and camera images from the mooring at http://seahurst.apl.washington.edu/mars. Among the engineering challenges was equipping the mooring with a motorized vehicle that travels up and down measuring conditions in all 100 feet of water and not just at one spot, says senior engineer McGinnis, co-principal investigator and project manager.

“We need to be able to measure from the seafloor to the sea surface if we are to understand how things like carbon, heat and nutrients move around because of the currents,” he says.

Along with standard salinity-temperature-pressure measurements, the mooring is equipped with such things as a hydrophone to listen for sounds, a chlorophyll fluorometer that can measure the abundance and productivity of phytoplankton, and an acoustic doppler current profiler to measure the velocity and direction of the currents. The researchers plan to leave it in place until this fall.

The video camera is connected to the node in shallower water, and that node will be permanent.

Students with the Puget Sound Skills Center’s marine technology program have already been taking advantage of the video, according to Joe Weiss, their teacher and a collaborator on the Seahurst Observatory.

“The video motion sensor archives are allowing students to keep a data log of all the species that swim or crawl by the camera,” Weiss says. “This requires the students to identify the species — and confirm the identification with other students. As the data log develops, students will be able to make observations on the frequency of sightings and even the behavior of common Puget Sound marine animals. Through the years students will be able to compare their data to observations by previous students and perhaps make predictions on the frequency of marine visitors.”

Along with the video recorder, instruments to measure temperature, pressure and salinity are plugged into the shallower node and visitors to the Web site can see the latest readings. A weather station on shore provides real-time data to compare with underwater conditions.

“One of the advantages of a cabled observatory is that we are not limited by batteries or data storage capacity and can therefore sample much faster than we would in a more typical autonomously deployed instrument, on a traditional mooring for example,” says Gobat, a co-principal investigator on the project. He lives near Seahurst Park and it was his idea to collaborate with the Puget Sound Skills Center.

“One goal of the observations is to look for long term trends and watch variability with changes in weather and seasons. For that we could be sampling more slowly. With a long time series of high sample rate data we can do things that we couldn’t have done before, like looking at things on shorter or faster time periods using statistics.

“What causes those little wiggles in temperature? Bursts of wind stirring things up and moving water heated by the sundown? Movement of the water with the tide? This kind of observatory gives us the ability to address those kinds of questions on a broad range of scales.”

The difficulties of operating an observatory like the one at Seahurst don’t just entail engineering puzzles concerning equipment and cables. Look at the top of the Seahurst Observatory Web site and you’ll see a screen that will play the most recent of the video clips that are taken each day. Right now, unfortunately, even if a seal or fish were swimming by it would be impossible to tell because the camera lens is so coated with diatoms, single-celled algae found in the water that are an important food source for marine organisms.