We’ve been spending quite a bit of time talking about diving and still are not quite yet done with the "Diving in Antarctica" journal entry series. But I thought that this week I’d talk a bit about what we see on those dives. I might just as well start with what we see most, which are macroalgae (or "seaweeds", which means pretty much the same thing as "macroalgae").
The macroalgae are a natural first thing for me to talk about anyway. Although my students and I also study bacteria and marine animals, most of my formal background is in the study of algae and the macroalgae are certainly my first love (academically speaking). 8^)
Phycology is the study of algae and more than anything else I think of myself as a phycologist. Phycos is the Greek word for algae while the word algae is from Latin. The suffix -olgy is also Greek and the first part of the name for a field of study should come from Greek too. So that is why it is "phycology" even though that word sometimes gets confused with "psychology."
The part of Antarctica where we are, along the western side of the Antarctic Peninsula, is close to heaven for a phycologist. The benthic (meaning ocean "bottom") communities are dominated by huge macroalgae except in places where the bottom is very silty instead of rocky. In a study I did here in 1989, we found an average biomass of 4.3 kilograms of macroalgae per meter squared on the bottom. That may not mean much to you but another way to put it is 17.1 tones per acre (or about 22.6 tones in the area of a football field if I did the math right). That is a lot of algae!
Macroalgae come color coded: green, brown, and red. The colors come from pigments that the plants use to capture light for photosynthesis. All photosynthetic plants have a pigment called chlorophyll a. That is what makes the plants you are used to seeing on land green. Essentially all plants have other pigments that help and they can make the plants have different colors.
There is only one species of green macroalgae here at Palmer that lives completely submerged all the time (that is, subtidal) although there are several species that grow in the intertidal. But the subtidal is dominated by huge brown macroalgae and, although not as plentiful in terms of biomass, there are many species of red macroalgae too.
Don’t ever let anyone tell you that there no forests in Antarctica. As I often say when I’m giving talks, there are indeed forests, but they are forests of brown macroalgae. Some species can cover 100% of the bottom in some places and rise a meter or more (3-4 feet) up. Another huge, flat species can spread out across the bottom for over 50 feet and be 3 or 4 feet across. Those too can cover 100% of the bottom in some places. And in deeper water, there is a species that has floats and can rise up 6 to 7 feet off the bottom. Very impressive organisms!