16 February, 2002
Phytoplankton are plants (algae) of the ocean. They come in many sizes, colors, and species. You need to look through a microscope to see these individual plant cells. However, during the growing season, there are "blooms" of phytoplankton. Then it is possible to see large amounts of phytoplankton in the water. Phytoplankton, like other plants, need energy from sunlight in order to grow. They use sunlight and their own chlorophyll to turn the minerals in the water into "food" and growth.
Phytoplankton are important parts of the food web. Small animals in the ocean (zooplankton) eat phytoplankton. In turn, the zooplankton are eaten by larger animals. So, it is very important to know about the phytoplankton growing in the Palmer LTER region. (For more information about this food web, visit the Polar Science Station at http://literacynet.org/polar/pop/html/project-ecosystem.html)
The Palmer LTER phytoplankton group is lead by Dr. Maria Vernet. This group studies phytoplankton in the waters of the Southern Ocean. The group also studies the phytoplankton in the waters close to Palmer Station.
These scientists want to know what kinds of phytoplankton are growing here, and how fast they are growing. To do this, scientists study "the water column". Picture an imaginary tube or column of water that goes from the surface down to the ocean floor. If you could take pieces of that column from the surface to the bottom, you could have an idea of what is growing in the water there.
That is exactly what the phytoplankton group does! The group members go out twice a week in the Zodiac called "Bruiser". The scientists want to take water samples at places in the water column where the light is 100% (of the surface light), 50%, 25 %, 10 % , 5%, and 1%. The depths of those light levels will change, depending on what is in the water. (If there is a lot of thick phytoplankton near the water surface, that patch of plankton will block out any sunlight in the water below them)
The group first puts a PRR (Profiling Reflectance Radiometer) in the water. This measures the levels of light at various depths in the water column. The information is sent back to a laptop computer on the Zodiac. For example, the 1% light level could be 75 meters deep in the water column. Or, because of phytoplankton bloom, the 1% light level could be very shallow, as it is now. That level now is only 13 meters deep.
Then the team members know where to get their water for that day! They put a line over the side with a Go-Flow bottle on it. They send a "messenger" down the line to close the Go-Flow bottle when it is at the proper depth. They bring up 4 liters of water from each light level. This water sample goes into a container on the Zodiac. The container of water is put into a cooler. The scientists also tow a net for other samples. They do this at stations B and E on the Palmer LTER map grid.
Then the scientists bring the water samples back to Palmer Station. They study the plants in this water in many ways. The scientists pour some of the water through filters. Then they use a microscope to look at the plant cells that remain on the filters. The scientists use another process to measure the color pigments in the cells. Finally, they set up some experiments to study the growth of plant cells at different light levels.
That's the way scientists learn about these important plants in the ocean!!
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