Phytoplankton Research

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Amy Shields, a graduate student with Dr. Kam Tang of William and Mary College, showed me around her lab and told me about her research with a particular type of phytoplankton called Phaeocystis antarctica. This tiny one-celled plant is at the bottom of the marine Antarctic food chain, but not much is known about this particular species. This organism has a period where it wanders around as a single cell, but later it seems to clump together with others of its species into a colony and secrete mucous to hold the colony together. The colonies are yellowish. They take up carbon and produce volatile organic sulfur into the water.

The group is looking at whether the solitary forms differ from the group forms in growth, composition or photosynthetic rates. They also are looking at how the zooplankton that feed on these phytoplankton and the nutrients available affect the colonies.

To do these studies, they have a dive hole on the sea ice behind Crary Lab where they bring up water samples with the phytoplankton. They then filter out specific amounts of the organism and put it into sample bottles which they keep in an environmental chamber that keeps the water at just the right temperature. They can change the nutrient levels and the number of grazers (zooplankton) in each sample bottle, as well as control light levels and turbulence within the bottles. Amy does some work with radioisotopes to trace the carbon uptake and emissions from these tiny critters. It is a complex and interesting piece of work they are doing. This is Amy’s fifth season at McMurdo.

This is just one example of the many types of biological research that go on in Antarctica.

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Photos

Solitary p. antarctica
A view through microscope of the solitary stage of the organism. Photo by Amy Shields. Borrowed from webpage at http://www.vims.edu/phae/

Colonial p. antarctica
A view through microscope of the colonial stage of the organism. Photo by Amy Shields. Borrowed from webpage at http://www.vims.edu/phae/

Bottle with Colonies of Organism
The yellow spots in this bottle are colonies of p. antarcticus.

Amy & Dr. Tang Take Samples
From a large carboy, the researchers take measured samples of water.

Samples Have To Be Exact
The sample wasn't exactly the right amount in this cylinder, so Dr. Tang pours some back into the carboy.

Making Separate Samples
Dr. Tang pours two cylinders of the sample into a small jug.

Adding Sea Water
Filtered seawater (no organisms) at just the right temperature is added to the sample so the organisms have plenty of room to move around and grow

Filter Apparatus
This is the filter they use to separate out their organism. Using different size filters allows them to filter out different grazers too - the critters that eat the phytoplankton. They keep these for studies of the relationship between the phytoplankton and the zooplankton. Zooplankton are one celled animals while phytoplankton are one celled plants.

Storing Some Samples
Some of the sample bottles are put into a sea water bath to keep them the right temperature for later use.

Environmental Room
These researchers have an environmental room that is kept at the temperature of the water (It's fairly cold). This is a table where they can put the sample bottles. They can then control the amount of light the samples get while they measure the growth, carbon uptake and sulphur output. They can also put grazers in some of the bottles to see how the light affects the amount of p. antarctica they eat.

Rotator
These organism live in the sea where currents and tides move them around. When they are in sample bottles, they tend to clump at the bottom. So they have this rotator device that slowly moves the bottles around so that the organism stays distributed throughout the sample. It works a lot like a ferris wheel except that the bottles are upside down part of the time.

Spectrophotometer
Amy uses this to measure how much carbon the organisms in a sample are giving off and taking up. She has injected some of the organisms with radio isotopes of carbon. This helps her understand their growth pattern.

Opening The Dive Hole
Adriana Veloza, a master's student, opens the dive hole so more samples can be taken.

Comments

[Heather B.]

Excellent photos
Keep up the great work on this blog! I happened upon this site and am fascinated by all that happens at McMurdo. My friend Dr. James Ramseier M.D. is currently there, please say hello for me!