11 July, 2004
Although I am still waiting to start my part of the science work on board, Peter Lee has already been collecting samples for his work. Originally from New Zealand, Peter is now doing post doctoral work in biogeochemistry at the College of Charleston in South Carolina. On this cruise, he is looking at DMSP (dimethylsulfoniopropionate). Why is DMSP important? It's a substance found in phytoplankton (tiny plants found in the water) that is released when they die. Bacteria turn the DMSP into DMS, a gas that's eventually released into the atmosphere and is extremely important in the formation of clouds. Among the biggest producers of DMS are coccolithophorid species of phytoplankton. It's not really important that you know that name, but it's really cool if you say it out loud! Anyway, these plankton are found most often in polar (or high latitude) oceans. From 1987-2002, there was an algal bloom (huge production) in the Bering Sea. In this case, it was a non-native species of phytoplankton called Emiliania huxleyi, one of the coccolithophorids. Scientists believe the bloom might be the result of a warming trend that made the conditions in the Bering Sea favorable for a bloom of this non-native species. One interesting note is that the coccolithophorid species have a calcium carbonate (limestone) exoskeleton (skeleton on the outside), and the ocean turns milky white when the bloom occurs. These algal blooms can actually be spotted from satellites if the weather is clear!
Peter is hoping to discover if this bloom is causing an increase in DMS production or if the new species is simply replacing other producers of DMS with a net result of no added DMS. They only have data from 2001; so much of his work is to establish baseline data for future comparison. He will also collect HPLC (high performance liquid chromatography) pigment data. Basically, he is analyzing the pigments (colors) in the phytoplankton in order to determine how much of each species is present.
To do all of this, Peter will collect water in two ways. First, he collects the ship's seawater using a pumping system to collect underway samples every 10 nautical miles at a fixed depth. He will also collect water from the CTD (conductivity, depth, temperature) bottles. These are bottles that collect water at different depths at stations along our route. In both cases, he filters the water and either stores the filters in methanol or freezes them at temperatures below minus 80 degrees Celsius. The tricky part is getting the frozen filters to stay frozen until we get to Barrow where Peter will get a fresh supply of liquid nitrogen for his freezer! Once he gets the samples home, he will analyze the pigments and the DMSP.
So, how does this fit into the big picture of global warming? If, with global warming, there is a shift to more DMSP producers, this could eventually lead to greater cloud formation and therefore greater cloud cover. Greater cloud cover would mean an increase in the earth's albedo (reflectiveness, or the ability to reflect back the sun's rays) and the earth would cool as a result. It's very possible that phytoplankton, those tiny aquatic plants, exert some control over earth's climate! If you have heard of James Lovelock's Gaia hypothesis, this is sort of a natural extension, or what some call geophysiology.
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