Lindsay Knippenberg: Oceanography Day! September 11, 2011

NOAA Teacher at Sea
Lindsay Knippenberg
Aboard NOAA Ship Oscar Dyson
September 4 – 16, 2011

Mission: Bering-Aleutian Salmon International Survey (BASIS)
Geographical Area: Bering Sea
Date: September 11, 2011

Weather Data from the Bridge
Latitude: 58.00 N
Longitude: -166.91 W
Wind Speed: 23.91 kts with gusts over 30 kts
Wave Height: 10 – 13ft with some bigger swells rolling through
Surface Water Temperature: 6.3 C
Air Temperature: 8.0 C

Science and Technology Log

On a calm day letting out the CTD is easy.

On a calm day letting out the CTD is easy.

Today Jeanette and Florence took me under their wing to teach me about the oceanographic research they are conducting onboard the Dyson. At every station there is a specific order to how we sample. First the transducer, then the CTD, then numerous types of plankton nets, and then we end with the fishing trawl. The majority of the oceanographic data that they collect comes from the CTD (Conductivity, Temperature, Depth). The CTD is lowered over the side of the ship and as it slowly descends to about 100 meters it takes conductivity, temperature, and depth readings. Those readings go to a computer inside the dry lab where Jeanette is watching to record where the pycnocline is located.

The results from the CTD. Can you spot where the pycnocline is?

The results from the CTD. Can you spot where the pycnocline is?

The pycnocline is a sharp boundary layer where the density of the water rapidly changes. The density changes because cold water is more dense than warm water and water with a higher salinity is more dense than water that is lower in salinity. So as the CTD travels down towards the bottom it  measures warmer, less salty water near the surface, a dramatic change of temperature and salinity at the pycnocline, and then colder, saltier water below the pycnocline. Once Jeanette knows where the pycnocline is, she tells the CTD to collect water at depths below, above, and at the pycnocline boundary. The water is collected in niskin bottles and when the CTD is back on deck Florence and Jeanette take samples of the water to examine in the wet lab.

Filtering out the chlorophyll from the CTD water samples.

Filtering out the chlorophyll from the CTD water samples.

Back in the lab, Jeanette and Florence run several tests on the water that they collected. The first test that I watched them do was for chlorophyll. They used a vacuum to draw the water through two filters that filtered out the chlorophyll from the water. As the water from the CTD passed through the filters, the different sizes of chlorophyll would get stuck on the filter paper. Jeanette and Florence then collected the filter paper, placed them in labeled tubes, and stored them in a cold, dark freezer where the chlorophyll would not degrade. In the next couple of days the chlorophyll samples that they collected will be ran through a fluorometer which will quantify how much chlorophyll is actually in their samples.

Jeanette collecting water from the CTD.

Jeanette collecting water from the CTD.

Besides chlorophyll, Jeanette and Florence also tested the water for dissolved oxygen and nutrients like nitrates and phosphates. All of these tests will give the scientists a snapshot of the physical and biological characteristics of the Eastern Bering Sea at this time of year. This is very important to the fisheries research because it can help to determine the health of the ecosystem and return of the fish in the following year.

Personal Log

One of the high points for me so far on the cruise has been seeing and learning about all the new fish that we catch in the net. We have caught lots of salmon, pollock, and capelin. The capelin are funny because they smell exactly like cucumbers. When we get a big catch of capelin the entire fish lab smells like cucumbers…it’s so weird. We have also caught wolffish, yellow fin sole, herring, and a lot of different types of jellyfish. The jellies are fun because they come in all different shapes and sizes. We had a catch today that had some hug ones and everyone was taking their pictures with them.

Now that is a big jelly fish.

Now that is a big jelly fish.

Today we also caught three large Chinook or king salmon. Ellen taught me how to fillet a fish and I practiced on a smaller fish and then filleted the salmon for the cook. What is even cooler was that at dinner we had salmon and it was the fish that we had caught and I had filleted. Fresh salmon is so good and I think the crew was happy to get to enjoy our catch.

The catch of the day was a 8.5 kg Chinook salmon.

The catch of the day was a 8.5 kg Chinook salmon.

Salmon for dinner, filleted by Lindsay.

Salmon for dinner, filleted by Lindsay.


What else did we catch?
Walleye Pollock

Walleye Pollock

A juvenile Wolffish

A juvenile Wolffish

Yellow Fin Sole

Yellowfin Sole

 A squid

A squid

Herring

Herring

Lots of little Capelin

Lots of little Capelin

Jillian Worssam, July 19, 2008

NOAA Teacher at Sea
Jillian Worssam
Onboard U.S. Coast Guard Vessel Healy
July 1 – 30, 2008

Mission: Bering Sea Ecosystem Survey
Geographic Region: Bering Sea, Alaska
Date: July 19, 2008

Numerous times over the past two and half weeks I have mentioned the CTD, small ones attached to moorings, there is one on the MOCNESS, there are even CTD sensors aboard the HEALY, but what does this CTD really tell the scientists?

For every sampling station the CTD needs to be prepared ahead of time so that all the equipment is functioning fully.

For every sampling station the CTD needs to be prepared ahead of time so that all the equipment is functioning fully.

As a review, let’s remember that a CTD records the Conductivity of the water that when adjusted for Temperature gives us salinity. The Depth of each sample is recorded because the ocean is not static; it is constantly moving both vertically and horizontally, and changing as it moves. When you sample with the CTD you can add a variety of accessory sensors to measure other ocean parameters: O2 salinity, temperature, pressure, fluorescence, turbidity and on our specific cruise we are also collecting data in regards to micro-zooplankton, nitrates, iron, and radon.

Each line represents a different element that the CTD is measuring.

Each line represents a different element that the CTD is measuring.

Let’s stop for a moment and talk about ocean currents. There are three ocean currents that affect the ecosystems of the Bering Sea: The Alaska Coastal Current, heavily freshwater, colder runoff that shoots through Unimak Pass; The North Pacific Gyre, warmer(relatively) water that seeps through the entire Aleutian chain, like water through a sieve. And the deep ocean conveyor belt, this one actually comes from the Mediterranean…water that has not seen the surface for a thousand years or more! This dense and cold fluid flows through Kamchatka pass, and has traveled from the north Atlantic through the Pacific to get to the Bering Sea, and is really rich in nutrients. No wonder it takes a thousand years. Anyway here we have all this water filtering into the Bering Sea, and here on the HEALY we have the CTD to give us precise data on the composition of this water.

The scientists all getting their water samples out of the 30 liter bottles.

The scientists all getting their water samples out of the 30 liter bottles.

During the actual cast of the CTD at each recorded station 24 data points are collects each second, giving an excellent representation of each specific water column. It is Scott’s job to run the CTD and let me tell you this is no easy task. The electronic equipment has to be constantly calibrated, the physical instrument array maintained, and all the collected data cataloged and stored for transmission to all the scientists both during and at the end of this cruise. None of this is an easy task. I also find Scott’s role on the vessel fascinating. Scott is an engineer who works for Scripts out of California and is hired on as outside technical support. He is not technically one of the scientific team, not technically part of the U.S. Coast Guard, and the HEALY could not technically collect most of their data with out him!

Hamming it up, Scott shows us the real science behind the CTD.

Hamming it up, Scott shows us the real science behind the CTD.

Quote of the Day: If you plan for a year, plant rice. If you plan for ten years plant trees. If you plan for 100 years, educate your children. Chinese Proverb.

FOR MY STUDENTS: What is a pycnocline?