Going Deep With Photosynthesis

This morning was Feb. 2 for us–Groundhog Day. I looked out the window but saw no groundhogs. I didn’t even see any ground. The really odd part was that in the afternoon we crossed the International Dateline and the date turned back to February 1st. That means that when I wake up tomorrow morning, it’s going to be Groundhog Day again. I feel like I’m in a movie.

That feeling of déjà vu persisted as I followed Dr. Angelicque White, Katie Watkins-Brandt, and Dr. Allen Milligan of Oregon State University around. Each of them told me one part of how they measure how fast phytoplankton conduct photosynthesis.

It seems like a simple question: how much carbon do the tiny plants produce, and how much light do they use to do it? But it took most of the afternoon to get it through my head. I toured a succession of labs crammed with sensitive analytical equipment, hooked together with rubber and plastic tubes of every size, propped up with pieces of wood, and held fast to the counters with bungee cords and bits of string. Oceanographers are like hermit crabs—constantly moving in to new spaces where their belongings don’t quite fit.

As far as I can tell, measuring photosynthesis involves filtering small things like phytoplankton cells from the water, shining expensive lights on them, and measuring how much light comes back. Then, to correct for some imperfections in this method, you filter out some even smaller parts of the cells and shine a different expensive light on them.

This happens about three times, and then you take the answers from each of those operations, multiply some of them and divide by the rest, and you get the answer. It’s actually quite fascinating, and it all makes sense as long as you have someone like Dr. White or Dr. Milligan to explain it to you. Read on through the slideshow to see what I learned:

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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.

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