Today we moved forward on our model. I'm studying coccolithophorids, which form the base of the food chain in all of the world's oceans. They are a species of phytoplankton, which billions of years ago revolutionized the world by spewing out ridiculous amount of oxygen, an element that had theretofore been somewhat rare in the Earth's atmosphere. The electron hungry ions of this element can be very harmful to fragile organic matter and other kinds of molecules. Scientists say that had the earth started with oxygen in its atmosphere like there is today, life never would have arisen at all.

Coccolithophorids are unique among phytoplankton in that they construct shells around their one-celled bodies out of calcium carbonate. In fact, their remains make up all of the chalk on earth, including the white cliffs of Dover, which are a remnant of a huge bloom of coccolithophorids that died long, long ago.


Each hubcab-shaped plate is fabricated inside the single celled organism and then exported to the outside to become part of its armor.

The type I am studying is the most common, Emiliana huxleyi. It has dominated the world ecosystem for millions of years. The sheer biomass of these algae outweighs every other living thing in the ocean combined.

Anyway, these creatures synthesize a molecule called an alkenone, which some people think they use to regulate the porosity of their cell membranes. The alkenone comes in several different forms, diunsaturated, triunsaturated, and in some cases tetraunsaturated. Unsaturated just means it has a different kind of bond in some places on the chemical structure. Ranor explained the organic chemistry to me, it was great, he's the knowledgable type.

Anyway, the type of alkenone that the coccolithophorid sythesizes depends on how cold the water is around them when they are making it. This means that the record of the temperature of the sea water is captured in the alkenone ratio in the cell at the precise moment that the molecule is created. The ratio sticks even when the algae dies and sinks to the bottom of the ocean. This proves to be quite useful because the ocean is covered with sediment from these "skeletons", waiting to become the chalk of the future. By digging up the sediments and knowing how old they are because of isotopes and marker fossils, we can say exactly what temperature the ocean was at that time. The kind of resolution that is possible is yearly ocean temperatures. Tracking these through time, we can see how the ocean changed and by proxy how the whole global climate changed, through millions of years.

However, there are some limitations. It was discovered experimentally that alkenones had this property of recording sea temperature, there is no physiological reason why it should be so. When scientists started to experiment with regard to this question, they found that several things affect the alkenone ratio, not just the water temperature. So how accurate is the alkenone ratio as a thermometer? Well that's just the question on everyone's mind! Well. Maybe not everyone's mind. Some people think it could still be very accurate, if we factor in the other variables that could affect it (like illumination, nutrients, strong cross currents, etc) For my part, I'm helping the great frenchman X. Giraud make a model that accurately predicts sea water temperature from alkenones, taking all of these other variables into account. In practical parlance, this means that I stare at graphs all day and try and think about what mathematical functions would best describe them. Do I think nutrients and such are related to the total number of alkenones directly? Inversely? Maybe Alkenones=1/(nutrients)^2?

This is where all that stuff you learned in pre-calculus about reading graphs comes in mighty handy. I have to make sure that my equation works--- if the nutrients go to zero, should that make the growth rate go way up, or stall? If I did it right, plants can't grow without nutrients, and taking them away should cause the growth rate to go to zero. It's complicated and my model isn't right yet. But X. and I can only wrack our brains for so long before it seems pointless. Here's where the computer comes in. We simply insert the equations I made up into a script X. wrote that has all of the things that algae are usually exposed to: surface wind, currents, upwelling of nutrients, differences in sun and darkness hours depending on latitude and time of year, etc. Basically we insert my equations into Xavier's world, hit "go" and see what happens. That's probably what I'll be doing for the rest of the week. Meaning... tomorrow. Then maybe I'll say tchuss to Bremen and go to Copenhagen!!

SWEET!
i love that kinda stuf. but not enough to do it thst often. lol, sucks to be you. have fun
» middaymoon on 2006-07-06 09:56:32

NOW I know what you are doing.....kinda
» Dad (71.229.162.28) on 2006-07-09 09:10:40

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» Bret (91.121.71.166) on 2011-06-08 01:38:33

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