Tuesday, January 29, 2013

Antarctica Expedition: Food Webs and Vacuuming

Aquarium senior educator Jo Blasi is on expedition to Antarctica to help study the impact of climate change in these areas and changes in the marine ecosystem. She will be live blogging frequently about the expedition, research technologies and marine life encountered during the trip.

First, a quick update: After 29 straight days of calm weather, we ran into a nice 50-60 knot gale yesterday, just in time to pick up the NSF representatives at Rothera and start the mooring deployments. It has calmed down some, so we managed the first deployment at 200.140, and are moving on to the 300 line for the pair of moorings and the recovery of the two gliders.  (You can follow us by tracking the ship.)

Typical types of phytoplankton along the Western Antarctic peninsula.

While I wait for the seas to calm, I wanted to explain in a little more detail what I'm doing with all those CTD water samples. My team studies phytoplankton (algae), the tiny plants in the seawater that use sunlight as energy to make food and oxygen. While plants on land can be very large (for example, trees), the plants in the ocean for the most part are small with an average size being only around 50 microns in length.

We are studying the phytoplankton in the Antarctic because they are the base of the food web and our data suggests that the number of phytoplankton is changing as the West Antarctic peninsula is warming over the last few decades. Phytoplankton are found in the upper ocean where there is sufficient light to promote photosynthesis. Check out this sample from our 200.0.40 line on our sampling grid. Can you recognize any diatoms?

Phytoplankton sample from the 200.-040 line (Photo credit: Beth Simmons PAL/LTER)

We recently left our most southern sampling station near Charcot Island.  Here is what a water sample from the canyon looked like.

Charcot Canyon phytoplankton magnified! (Photo credit: Beth Simmons)

If you would like to learn more about Antarctic phytoplankton check out this page. How can we catch such tiny things? We take a sample of water from the CTD and extract the plankton by passing the seawater through tiny filters! It starts with water from the CTD being poured into the top of a funnel.  Then, a vacuum pulls the water through a special filter. The water ends up in a flask but the filters capture the plankton. These filters are frozen and sent back to Rutgers University for further examination when the crew returns to the states. Examining how much phytoplankton is on each filter informs scientists about what concentrations of phytoplankton are in the water in the area, where the water sample was collected from and what depth the sample was taken.

It can take a long time to filter seawater and I do it several times a day so here's a quick view of what it's like!  Check it out...

All of Jo's entries are cross posted on the Palmer Long Term Ecological Research Station site here. Track her progress on the R/V Gould, and learn more about the Palmer Long Term Ecological Research Station.

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