NOAA Teacher at Sea
Onboard U.S. Coast Guard Vessel Healy
July 1 – 30, 2008
Mission: Bering Sea Ecosystem Survey
Geographic Region: Bering Sea, Alaska
Date: July 16, 2008
Today I would like you to meet Kirby Krill, well not really Kirby, it could be Kathy. Whatever the gender “The Krill Grazers” are interested!
These five women work nights, waiting until dark to collect their samples. They only need one sampling station an evening where they send down the “bongo net” and retrieve their live critters. What the “Krill Grazers” are interested in is: What krill eat, and if their food choice changes seasonally. They also want to know: if the krill are given a choice, what would they choose to eat. This is similar to a salad bar mentality, give the krill everything, and see what food they prefer, thus the need for a live experiment.
For the first part of our experiment, enter Tracy. She is after the live samples and will choose 4 – 8 krill, depending on size. She will then place the krill in a four liter plastic container with fresh sea water and observe them for 24 hours. Prior to placing the krill in the container, Megan and Gigi will take a sample of the sea water, and at the end of the 24 hours will take another sample of the same water from the krill containers. They put the water through a filtering process and preserve the flora and fauna. Megan’s job then continues back at the lab in Washington. That is when she will count and identify both pre and post samples to determine what the krill are eating. In the mean time, while still on the ship, at the end of the experiment, Tracy will remove the krill from their incubator, measure them, and figure out what species they are. This information will be important later when looking at the results of the experiments in order to understand whether larger krill are eating more or different types of food than smaller krill.
The sea water is collected with a CTD so the scientists can exactly match the depth from their live tow on the bongo and the CTD. So why are five women from three different states (Oregon, Washington and Maryland) working collaboratively on krill? Krill are a food source for many other species: fish, birds, baleen whales, and many other animals eat krill to live. Even the seals that eat fish need krill, for the fish have eaten krill. An oceanic food web is not complete without our little zooplankton buddies.
There is a lot more science to the grazing of krill, I haven’t even touched on what Rachel does and it involves the removal of the krill’s eyes. So check in tomorrow for “Grazing with krill.”
Quote of the Day: One touch of nature makes the whole world kin. William Shakespeare
FOR MY STUDENTS: What is an example of a microscopic plant or animal that might live in an Arizona aquatic ecosystem?