Mark McKay, June 19, 2009


NOAA Teacher at Sea
Mark McKay
Onboard Research Vessel Knorr
June 10 – July 1, 2005

Mission: Ecosystem Survey
Geographical Area: Bering Sea, Alaska
Date: June 19, 2009

Sediment Trap Buoy along side the Knorr

Sediment Trap Buoy along side the Knorr

Science Log

Some very interesting activities have been going happening on board the Knorr the last couple of days. While everyday there is a routine of cruising to a station, stopping and dropping plankton nets and/or other probes, other, more exotic experiments get deployed. For example, yesterday researcher Pat Kelley from the University of Rhode Island and his team retrieved sediment traps that they had set out 24 hours before. Their interest is seeing what is settling to the bottom of the ocean and at what rate this material is settling. To do this, they use a rather ingenious device. They take tubes and fill them with salt water that is many times more concentrated then regular seawater. Because it is so dense, the concentrated saltwater stays in the open toped tube as it is lowered into the ocean.  Anything that falls into this liquid stays in the trap and can be recovered for analysis. That’s where it gets interesting. Deploying and then recapturing a drifting probe can be a little tricky. After letting the sediment trap loose for 24 hours, you first have to go back and find it.

Lefting Buoy onto Knorr deck

Lefting Buoy onto Knorr deck

Fortunately the trap uses a satellite beacon that broadcasts its position to the ARGOS satellite system. The Argos program is administered under a joint agreement between the National Oceanic and Atmospheric Administration (NOAA) and the French space agency, Centre National d’Etudes Spatiales (CNES). The system consists of in-situ data collection platforms equipped with sensors and transmitters and the Argos instrument aboard the NOAA Polar-orbiting Operational Environmental Satellites (POES). The Argos system will lead you right to your instrument, then you have t get it on board. After they locate the instrument, they bring the ship along side and “lasso” so the deck crew can attach a cable and lift it out of the water using the A-frame crane located on the aft portion of the ship. The sediment traps are attached to a long line comprised of a heavy weight at one end with floats and a buoy at the other. The device is separated and brought up in sections so that they can be brought aboard using one of the ships cranes.

Removing float section of Sediment Trap

Removing float section of Sediment Trap

This takes a lot of skill to do, especially when on a deck that is slippery and rocking with the waves. Remember that this is done in between the other experiments and device tows. The deck crew is probably the busiest and hardest working group on this cruise. Another group on the cruise is the U.S. Fish and Wildlife Service “bird people” as they seem to be know as on the ship. They are made up of Elizabeth Labunski and Sophie Webb, both of which position themselves on the ships bridge so that they can survey what birds and marine mammals are present in-between stations. The Eastern Bering Sea is a very productive area and is rich in bird life.  I went up to visit them on the bridge.While there they identified a rather unhappy Red-legged Kittiwake (Rissa brevirostris) sitting rather pitifully near the bow of the ship.

Collecting Sediment Trap Tubes

Collecting Sediment Trap Tubes

These birds are interesting because as opposed to their Black-legged cousins, they have a very narrow distribution. According to the Audubon Society, Red-legged Kittiwake’s breeding distribution is limited to just four localities in the Bering Sea: Alaska’s Pribilof Islands, Bogoslof Islands, and Buldir Island, and Russia’s Commander Islands. More than 75% of the species’ known population breeds on St. George Island in the Pribilofs, which were about 40 miles from where we were cruising. The weakened bird was captured so that it could be warmed up and released when it regained its strength.

 

Elizabeth Labunsk and Third Mate Alison Paz surveying Bering Sea birdlife

Elizabeth Labunsk and Third Mate Alison Paz surveying Bering Sea birdlife

Red-legged Kitiwake

Red-legged Kitiwake

Sophia Webb holding Red-legged Kittiwake

Sophia Webb holding Red-legged Kittiwake

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