May 20, 2006 – Northward!, Sampling Above St. Lawrence Island Options

[Patricia_Janes]

May 20, 2006 – Aboard the Healy
Longitude: 171 37.00 W, Latitude: 64 17.00 N

Today we sailed around St. Lawrence Island to begin sampling the water and seafloor sediments north of the island. So far, all of our sampling has been south of St. Lawrence.

At one point during our journey northward, we crossed the International Dateline and were in what is called the Russian Exclusive Economic Zone. An important point: The nautical right of innocent passage allows us to cross into water claimed by Russia, but we cannot sample there. At one point during our transit, we were closer to Russia than we were to U.S. soil: just 19 miles to Russia, and 31 miles to St. Lawrence Island. This was only the second time that I have seen land since setting sail two weeks ago.

So what part of Russia was I seeing? For that information, I turned to Mikhail Blikshteyn who currently lives in Juneau but is originally from Russia. Mikhail found a map and pointed to the Chukotsky Peninsula on the very eastern edge of Russia, part of a region known as Siberia. More specifically, I had seen the mountains that lie east of the Russian town of Provideniya.


At about 0730 this morning, we sailed northward at a distance of roughly 19 miles from Russia’s eastern coastline.

Once we were back in U.S. waters north of St. Lawrence Island, we began our sampling again. Depending on weather and ice conditions, we plan to stop at 23 stations here. The scientists are continuing to collect all of the same data as they have at the more southerly stations. Below is a listing of all of the data collection that occurs at each station. The scientists always conduct these activities in this order. However, if ice is present, they might skip some collections so they don’t damage their equipment:

1) Coast Guard crewmembers use a winch and pulley system to lower a large, heavy device called a CTD into the Bering Sea. The CTD contains various sensors and 12 empty canisters called Niskin bottles. The sensors measure the water’s temperature and conductivity (also a measure of how much salt is in the water). As the crewmembers lift the CTD back up, the 12 canisters collect water from the bottom, middle, and top layers of the water column. Several scientists share this water to perform various tests on it.


Casey Quitmeyer collects his share of water from the CTD’s canisters.

2) Next comes an optical instrument, usually referred to on the ship as the “UV meter.” The UV meter measures ultraviolet radiation and all of the radiation that plants can use. This radiation is known as “photosynthetic active radiation,” or PAR. So, among other things, the UV meter measures how far down light is reaching. The instrument sits at the end of a very long cable, which we lower to a depth of roughly 30 meters. It takes measurements once every second and sends the data though the cable to a laptop computer on the ship.


In addition to measuring the amount of light at different water depths, the UV meter also measures water depth, natural fluorescence, and temperature.


Here I am slowly lowering the UV meter over the side of the Healy. We always try to lower it on the sunny side of the ship.

3) Third is the zooplankton haul. Zooplankton are microscopic animals that float in oceans and lakes and are eaten by fish and other animals that live in water. To collect zooplankton, the scientists lower a large white net with very small holes. Water can pass through these holes, but the tiny zooplankton get caught. Then, we use a hose to wash the zooplankton down into a collection container that hangs at the bottom of the net.


The zooplankton net catches tiny critters that are floating in the water column.

4) Next we do seven van Veen grabs. For each grab, we lower a huge metal scooper to the seafloor and grab a chunk of the mud. With three of the grabs, we collect some of the mud so the scientists can study the surface sediments. The rest of the mud gets emptied into a wooden box with a screen at the bottom and gets hosed down with water. The mud and water runs out, while any shells or creatures that had been hiding out in the mud remain. With the other four grabs, the mud goes straight into the wooden box to collect the organisms so that the scientists can quantify the organisms present at each site.


When collecting sediment from the van Veen grab, it is important to scoop every last bit out of the metal device. Otherwise it would be difficult to compare the amount of matter from one station to another.

5) Next comes the HAPS core. This device consists of four empty tube-shaped containers that sit side by side. When the device hits the seafloor, the containers get shoved into the seafloor and fill with sediment and water. Samples from these cores are more intact than they are in the van Veen grab, so it almost like picking up a mini seafloor environment. Among other things, that enables the scientists to study the interaction of organisms in the core with the water and sediments.


The HAPS Core gets lifted from the Bering Sea.

6) Last comes the trawl. This large net gets lowered down to the seafloor and then the ship sails slowly—about the speed a person runs—for about 20 minutes. As the ship moves, the trawl collects the small animals that live on the seafloor such as clams, crabs, fish, sea stars, and more.


Mikhail Blikshteyn readies the trawl for lowering.