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Fieldwork

Voyage to Recover and Redeploy Instruments in the Adriatic Sea—the Good, the Bad, and the Ugly


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Microphotograph of bottom sediment at 9-m depth off the Chienti River
Bottom sediment: Microphotograph of bottom sediment at 9-m depth off the Chienti River. The fecal pellets contain fine sediment and were not present in some photographs after a strong Bora event (northeasterly storm). The mineral grains are coarse silt to very fine sand. Field of view is approximately 7 mm across. [larger version - 50KB jpeg]
U.S. Geological Survey (USGS) scientists and technicians took part in a recent voyage (mid-February to early March) to recover data from instruments deployed last fall in the Adriatic Sea.

The midwinter cruise was a continuation of the PASTA (Po and Apennine Sediment Transport and Accumulation) study. PASTA is a component of EuroSTRATAFORM, a research program using selected areas of the European continental margin to explore the fate of sediment particles from their sources in rivers to their deposition on shallow deltas, on the continental shelf, and in deep-sea basins. This article summarizes successes and problems encountered during the recent voyage.

The Good

USGS instruments deployed last fall have produced a spectacular record at our two sites off the Chienti River in Italy. Virtually complete records of waves, currents, temperature, salinity, and suspended-sediment concentrations between late November and mid-February were recovered from our instruments during the recent PASTA voyage on the Harbor Branch Oceanographic Institution's research vessel Seaward Johnson II.

These records document the persistent coastal current responsible for transporting sediment, nutrients, and contaminants southward along the Italian coast. Even two new instruments that had never been in saltwater before provided valuable records for the first part of the deployment. Dave Rubin and Hank Chezar's sediment microphotography device yielded intriguing photos of bottom sediment at the 9-m-depth site. The high-resolution scanning sonar, built by Chris Sherwood and Marinna Martini (USGS) with help from Jim Irish and Robin Singer at the Woods Hole Oceanographic Institution (WHOI), revealed bottom conditions that shifted between small ripples and upper plane-bed conditions.

The tripods were recovered by WHOI divers, with backup from USGS divers Chuck Worley and Dann Blackwood. Chuck and Dann dove to clear a line (not ours!) from the ship's propeller and ran sidescan-sonar surveys of the instrument sites.

Below left: Turbid plume of the Chienti River merges with the less turbid coastal current at the 9-m-depth site, about 1 km offshore of the Italian town Civitinova.
Turbid plume of the Chienti River merges with the less turbid coastal current at the 9-m-depth site, about 1 km offshore of the Italian town Civitinova. Slightly bent legs of the barnacle-encrusted flow tripod from the 9-m-depth site attest to encounters with fishing gear.
Above right: Slightly bent legs of the barnacle-encrusted flow tripod from the 9-m-depth site attest to encounters with fishing gear.

The Bad

Fishing pressure from small trawlers presents a major danger to oceanographic instruments off the Italian coast, and all three of our tripods had been hit at some point. One tripod was toppled on St. Valentine's Day (3 days before we recovered it!), the second was rotated 180 degrees early in the deployment and left slightly bent but fully operational, and the third was lifted briefly off the bottom but left in place. Despite these bumps and bangs, we got complete data sets (minus 3 days at one site). Other EuroSTRATAFORM investigators had worse luck: two other tripods were toppled earlier in the experiment, and four buoys were damaged or moved. Overall, the instrumentation array fared quite well, with nearly complete records from eight bottom-mounted sites, partial records from two more sites, and complete loss of data at only one site.

The Ugly

Satellite image of the Adriatic Sea taken by a Moderate Resolution Imaging Spectroradiometer (MODIS), showing sites of measurements.
Satellite image of the Adriatic Sea taken by a Moderate Resolution Imaging Spectroradiometer (MODIS), showing sites of measurements. [larger version with full caption - 50KB jpeg]
Biological fouling was pretty impressive, highlighting the excess-nutrient problem that plagues the Adriatic Sea. Some of our optical instruments shifted to barnacle-growth-rate sensors after the first month, but the acoustic sensors were mostly unaffected. The USGS team on board (which included Chuck, Dann, Hank, Marinna, Chris, and Joanne Ferreira) scraped and pressure-washed the instruments, downloaded data, made some quick repairs, changed batteries, reapplied the antifouling paint, and redeployed everything for 4 more months. Final recovery from the same ship will occur in late May–early June.


We owe much of our success in this turnaround to folks at the Marine Operations Facility in Woods Hole, MA (Dave [Twig] Nichols, Jonathan Borden, and Rick Rendigs), and their counterparts at the Marine Facility in Redwood City, CA (Dave Hogg, Dave Gonzales, Kevin O'Toole, and Hal Williams). These guys built and shipped the instruments (and critical spare parts and batteries) on a tight schedule.

The WHOI divers (Jay Sisson and Glenn MacDonald) were heroic, diving in cold water with strong currents and zero visibility to recover the tripods. Luckily, Stefano Miserocchi (one of our Italian coinvestigators) navigated to the sites with even better precision than his differential global-positioning system (DGPS) is theoretically capable of.

The captain and crew of the research vessel Seward Johnson II were outstanding, and Chuck Nittrouer (University of Washington) was responsible for coordinating the whole project and the difficult logistics of an overseas cruise involving 21 principal investigators from 11 institutions.

The study is funded by the Office of Naval Research and the USGS Coastal and Marine Geology Program's Community Sediment-Transport Modeling project.


Related Sound Waves Stories
The "Poking Eyeball"—a Prototype Underwater Camera System
April 2003
USGS Participates in Sediment-Transport Cruise in the Adriatic Sea
Dec. 2002 / Jan. 2003

Related Web Sites
Community Sediment-Transport Modeling Project
U.S. Geological Survey (USGS)
Office of Naval Research
U.S. Navy
Woods Hole Oceanographic Institution
non-profit research facility
USGS Marine Facility
U.S. Geological Survey (USGS), Redwood City, CA

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in this issue: Fieldwork Adriatic Sea Instrument Redeployment

Research Prototype Underwater Camera System

Outreach St.Petersburg 100th Anniversary

Environmental Symposium

Meetings Special Emphasis Program Advisory Committee (SEPAC)

Awards Marine Science Award

Staff & Center News Manheim Retires

Andrews Discusses Latest Novel

Publications April Publications List


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