Science is all done on the cruise. People have finished running their samples through the analysis and everyone is busy packing their labs. Seas are still very calm, although there is a bit more swell than in past days. Still very unantarctic
What do phytoplankton have in common with croissants? Aboard the Palmer, Emily Peacock is the right answer. Emily is in charge of creating a 'photo album' of as many organisms from the phytoplankton as possible. She works at the Woods Hole Oceanographic Institution (WHOI), in Woods Hole, Massachusetts. Let us find out how she gets the photographs she needs for the album, and what does all this have to do with croissants.
Emily sorts phytoplankton after the auto-sorter's first attempt. The picture is a bit dark so you can see the organisms on her computer screen.
Phytoplankton are single-celled plants that are found in the upper layers of the ocean where the sunlight can reach. They obtain their energy from the sun, like land based plants do, through a process known as photosynthesis. They use the solar energy to combine carbon dioxide (CO2) and water to form oxygen, which you and I breath, and carbohydrates (molecules with oxygen, carbon and hydrogen), which is what plants are mostly made of. They absorb the solar energy with particular pigments, the most common being the green chlorophyll. Different species have adapted to live in different parts of the oceans. Some scientists are interested on creating a catalog with all the species and where they are found. They also want to know the percentage composition of species in each community. Emily is part of a group lead by Dr. Samuel Laney, WHOI.
Emily collects water samples for obtaining the organisms in two ways. She samples every now and then from the main rosette, but only from the surface bottles (down to ~100 meters). There is no need to collect samples deeper than 100 m since there is very little sunlight at those depths, and therefore, very few phytoplankton. When Emily is not collecting samples from the bottles, water from just below the ship is taken through a hose by a pump to her lab, for a photo event.
Emily's instrument is quite a camera setup, as you can imagine given the size of the organisms she is photographing. The phytoplankton she is photographing range between 5 µm and 100 µm (1 micrometer (µm) = 0.000001 meter). The instrument samples 5 ml of seawater at a time and sends it slowly through a narrow glass passage called a flow-cell. Only one organism can go through the narrow passage at a time.
Sophisticated camera for phytoplankton pictures. The red laser illuminates the cell-flow
A laser beam shines on the thinnest part of the flow cell, which makes the chlorophyll in each cell of plankton fluoresce. A sensor detects the fluorescence of the chlorophyll and triggers the camera. Pretty ingenious! That way, the camera only takes a picture when there is an organism from the phytoplankton in the flow-cell. Not quite, zooplankton, animals that float in the upper layer of the ocean and rely on currents to move horizontally, can also be photographed because they have chlorophyl form the phitoplankton that they eat.
After the pictures are collected, the data analysis can begin. The pictures are first sorted with an auto-classification system, sort of like facial recognition like on a CSI show. Then, Emily uses additional software to manually correct the results of the auto-classifier. In the end, the auto and manual classification provide the results for the phytoplankton census.
Some phytoplankton you may find in Antartica (some of the ones Emily has found):
Assorted phytoplankton from the Southern Seas
Did you see any croissants in the process of photographing phytoplankton? Neither did I. It turns out that Emily is also an accomplished baker, and on nights that not much is happening in the labs, she finds her way all the way to the galley and convinces Ale to let her bake some yummy croissants and other pastries. Here she is placing a tray in the oven.
Emily placing the tray of her pastries in the oven.
I wake up after one of those nights once they have baked and eaten some of the pastries to find delicious treats awaiting for me and the rest of the day watch. They are irresistible!
Here is a picture of Emily, Ale and Jermaine, who also helps with the baking. My thanks to all three of them!
Ale, Jermain and Emily preparing delicious baked goods.