July 11, 2005 Options

[Betty_Carvellas]

July 11, 2005

Today we'll go through Unimak Pass and the science work will begin in earnest. First, however, we have a line of eight stations (a station is when the ship stops so that we can collect samples, either water or mud) south of the pass. The first will be at 1:30 PM, and we should finish the last by late this evening. Although I haven't started my work yet, I spoke with Dr. Peter Lee this morning, and he began his underway sampling early today. We're all amazed that Peter is functioning as well as he is because he came to the Laurier from a 45 day cruise from Florida, to the Azores, and on to Iceland. He left Reykjavik on July 7, and boarded the Laurier on the 8th. My "long" trip here is inconsequential by comparison! Peter is originally from New Zealand, but he's now doing postdoctoral work in biogeochemistry at the College of Charleston in South Carolina.

Peter's work involves sampling for DMSP (dimethylsulfoniopropionate), a substance found in the cells of phytoplankton (tiny plants found in the water) and for the pigments found in phytoplankton. DMSP not only helps the phytoplankton regulate salt (it's an osmoregulator), it's also a cryoprotectant (helps them to survive in cold temperatures) and it's an antioxidant. We've all heard about the benefits of antioxidants, so I asked Peter if anyone had thought of using DSMP for humans. He said that some have suggested a teaspoon/day of DMSO (an oxidation product of DMS), but it breaks down and leaves an unpleasant taste of oysters in your mouth. It's easier to eat carrots!

Peter collects his samples in two ways. Every hour that the ship is underway, he uses the ship's seawater pumping system to collect water for horizontal sampling. When we stop for a station and put down the CTD (conductivity depth, temperature) bottles, he'll collect water for vertical sampling. The CTD cast sends down a series of bottles that collect water at specified depths. Peter filters the water and takes the samples, stored at minus 80 degrees Celsius, back to South Carolina for analysis. He estimates that he'll bring back approximately 450 samples for analysis. At about 20 minutes/sample for the DMSP and 1 hour/sample, on an automated system, for the pigment samples, Peter and the lab technicians will be spending a great deal of time analyzing the samples from this relatively short cruise. While on his Florida to Iceland cruise, he did similar work but also added a specialized incubator system that manipulates the CO2 and temperature of a large batch of water in order to see how the phytoplankton adapt. Thus, he has a two fold approach to measure climate change. He can manipulate the phytoplankton community under controlled conditions and also look at how the natural community changes over time.



Peter will analyze each sample two ways. First, he uses HPLC (high performance liquid chromatography) to identify the pigments and therefore the groups of phytoplankton. Anyone who lives where the leaves change color in the fall knows that, when the chlorophyll dies back, the accessory pigments in the leaves show up to produce the brilliant colors that bring the tourists. Just as you can identify the type of tree by the color of the fall leaves, you can identify the major groups of phytoplankton by their pigments. He'll be able to identify how these groups change over the years due to climate change. For example, there could be a greater concentration of some species, or even new species moving in. That's exactly what happened when, from 1987 - 2002, there was an algal bloom (large production) of a non-native species of phytoplankton in the Bering Sea. Scientists believe a warming trend might have made the conditions more favorable for this new species.

Peter also analyzes DMSP concentrations in each sample using gas chromatography. By looking at this data along with the pigment analysis, he can evaluate how the DMSP concentration responds to the changing phytoplankton community. Since this is the fifth year of sampling at the same stations, Peter is developing a baseline for DSMP concentration and for the phytoplankton present. Scientists in future years will be able to document changes over time.

How does this work relate to climate change? If climate change means warming temperatures, there will likely be additional phytoplankton production, therefore, more DMSP produced. When the phytoplankton die and release the DMSP, it's broken down by bacteria into DMS and eventually to sulfates which are critical to cloud formation. So, it looks like this: warmer temperatures, more phytoplankton, more DMSP, more DMS and sulfates, more clouds, more cloud cover, an increase in the Earth's albedo (ability to reflect back the sun's rays), and cooler temperatures. Just possibly, the ocean's phytoplankton could help to regulate the Earth's climate! If my students are reading this, they may recognize the elements of James Lovelock's Gaia hypothesis. Scientists now refer to this "whole earth as a living organism" idea as geophysiology.