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Magic in Diatom Alley

Our position at 6 AM this morning

The waves were significant overnight, up to 14 feet, but it’s settled down a bit this morning. It’s still far from calm, though, with the wind at about 22 knots and waves crashing against the porthole before me. But it’s interesting how quickly the body adjusts; the rocking feels almost normal now. I’m pleased that I’m close to mastering the art of walking as opposed to lurching, although this morning, as I exited one lab with the intent of going along the passageway to the galley for breakfast, I inadvertently found myself stumbling halfway across the lab on the other side of the passage. But I stayed on my feet and didn’t bump into anything, which shows real progress since yesterday!

Antarctic petrels have joined the snow petrels following the ship. They appear to be playing as they skim the surface of the heaving waves, as if surfing the air currents, before swooping upwards, banking, and returning to the ship’s stern to do it all over again.

Since we’re not due to reach our first sampling station until sometime tomorrow, and since we’re set up and ready to go once we reach it, today will be fairly quiet for most of the science team. This is good since adjusting to the ship’s motion is making most of us a little sleepy. It’s the perfect day for visiting with Colin—aka the Diatom Wrangler—and Christina, our diatom micropaleontologist.

Colin will be working with live diatoms throughout the cruise, and the small cool room Jessica has dubbed Diatom Alley is ideal for recreating the summer Antarctic environment in which diatoms thrive. It can be kept at a constant, cold temperature, with constant light. Colin can also control the amount and type of nutrients the diatoms receive.

Christina and Colin say they’ve found some cool diatoms in the initial samples of seawater from the last two days.

Colin is isolating some individual diatoms to take home for some more sophisticated experiments once we are back in the lab at URI. I’m excited to see them through the microscope! A sea of intricate shapes lies before me, gleaming golden and translucent in the microscope’s light, miniscule plants in tiny glasshouses.

A photomicrograph of surface seawater at 40x magnification. Most of what is visible are diatoms, with a zooplankton (far left).

Corethron (400 x actual size). The green material in its middle section consists of chloroplasts, which the diatom uses during photosynthesis.

Diatoms come in many shapes and sizes. Scientists estimate there are likely over tens of thousands of extant (living today) species with a myriad of shapes. Some look like sand dollars or tiny slices of orange, others like minuscule rocket ships or alien beings. There are even some that look like fortune cookies, though we don’t expect to see those here because they are a fresh water species. Yes, diatoms are everywhere—in the ocean, lakes, streams, puddles, and even on damp tree bark and rocks. Scientists estimate that every fifth breath you take contains oxygen produced by a diatom during photosynthesis. Diatoms are part of the base of the food chain in both marine (ocean) and aquatic (fresh water) environments. They also act as a carbon sink, taking up more carbon dioxide—a major greenhouse gas—than all the tropical rain-forests on Earth combined.

We are interested in seeing how they respond to and record—within their structures—the chemistry of the water in which they are living. Ultimately, we will use these signatures to study where they were living in the past. We will be collecting fossil diatoms from the seafloor sediment. What we learn may help us reconstruct what their environment was like when they were living.

Jessica and Marty practice in preparation for removing sediment cores from megacorer tubes.

In the afternoon, the marine technicians teach us how to remove mud cores from the megacorer tubes without damaging them. The megacorer is a large piece of equipment that captures sediment (mud) from the seafloor. It is lowered on its frame until it reaches the sea bottom, then the weight of the center section (which is filled with lead) pushes the tubes into the mud. It’s so heavy that it takes less than a minute for the tubes to sink into the sea floor, but it takes much longer for the megacorer to reach the sea floor thousands of feet below us and return to the ship.

Everyone is excited and eager to get started—and we are less than 24 hours from arrival at our first site!

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