Sizing Up the Food Chain

The microscope room on the Palmer is just big enough for a slide preparation table and two bulky microscopes. It’s dark inside, and the microscope tabletops are designed to rock back and forth on an air cushion to counteract the ship’s rolling. As they do this, they make a deep sighing that sounds like Darth Vader is behind you.

Staring through a moving microscope and looking at a watery slide on a rocking ship in the dark is a prescription for seasickness. But the biologists on this voyage spend many hours per day in here counting cells, and I haven’t heard them complaining yet.

At one point Dr. Angelicque White sat me down and showed me some beautiful diatoms, including one that I called ‘grass skirt’ because it had a fringe of long spines around its middle. (Turns out it’s called Corethron). Ever since, I’ve wanted to look at some more examples of the microscopic citizens of the Ross Sea.

Today I got my chance as we dipped an 8-foot-long plankton net over the side of the Palmer. I looked at less than a tablespoon of that water, and still the microscope revealed a parade of plants and animals. We found at least four different levels of the food chain, each one a bit larger than the next. Read on through the slideshow and travel up the food chain with us:

There’s one more photograph we needed for this post, but we just couldn’t get it: a picture of you. Humans sit at the top of the food chain—we eat pretty much anything we want, and nothing else eats us. So even if you’ve never been to Antarctica, what you eat for dinner can weigh on the health of its ecosystems.

As alien and distant as the microscopic creatures in this post look, they’re just a couple of stops away from us on the food chain. Small fish and krill from the Southern Ocean are caught in great numbers to feed to farmed fish and shrimp. It takes many, many of these small creatures to end up with a few giant shrimp.

Even here in the remote Ross Sea, vessels are venturing farther south each year to catch Antarctic toothfish, which is sold as Chilean seabass. These large fish eat other fish that have fed on krill, so even they are only a few steps removed from the creatures in this slideshow.

Many thanks to Dr. Angelicque White and Dr. Scott Fay for help with the net sampling, petrel poop sampling and filtering, and microscope setup. You can find more information about where seafood comes from through the Monterey Bay Aquarium’s Seafood Watch program.

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Profile photo of Hugh Powell

About Hugh Powell

Hugh is a staff writer at the Cornell Lab of Ornithology and is on special assignment with the Rutgers University Institute of Marine and Coastal Sciences. He has previously written for the Woods Hole Oceanographic Institution.

5 Responses to “Sizing Up the Food Chain”

  1. Another great entry. I love the alien beauty of plankton. Chris and Hugh, you have done an amazing job of making the research and experience accessible to your readers.

  2. Erin from Newton High School February 12, 2011 at 2:12 pm

    How do you use a net to catch creatures as small as phytoplankton?

    • Profile photo of Hugh Powell

      Hi Erin, that’s a good question that actually has a pretty simple answer: we just use a net with very small holes in it. The one that we used to catch plankton has holes that are about a fifth of a millimeter wide in it. It looks more like thick fabric than the kind of big fish netting you might be imagining, but it does the same thing—it lets the water through and catches little plankton cells.

  3. Profile photo of Claire Barnett

    Beautiful photos, Chris! And so pleased you mentioned MBA’s Seafood Watch Program, Hugh.

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