The main focus of my time down here at Palmer is investigating the role of brown algal phlorotannins. Phlorotannins are a group of polyphenolic compounds that are involved in constructing and strengthening the cell wall in brown algae. This function is called a “primary” role, but we are actually only interested in their “secondary” roles, which include functions such as herbivore defense, antibacterial agents and as a UV “sunscreen”.
This season we are setting up an experiment which investigates the role of UV radiation in the induction of phlorotannin production. The increased levels of UV radiation associated with the Antarctic ozone hole are thought to be likely to continue for the next couple of decades, so the effects of increased UV radiation on the organisms living in Antarctica is of great interest.
As I mentioned above, phlorotannins often act as a feeding deterrent, so if we find that the concentration of phlorotannins do increase when we expose algae to higher UV levels, then this may have consequences for the animal populations that consume algae (e.g., snails and crustaceans). Increased levels of phlorotannins in our experimental algae may make them unpalatable to animals, and we will be testing this at the end of the experiment.
Our experiment involves transplanting two species of large brown algae (Desmarestia anceps and D. menziesii) from a depth of about 50 ft to a depth of 15 ft. We will attach the tips of these plants to several racks which are in turn attached to concrete blocks called “substrates.” So we call this the “substrate experiment.” One third of the racks will be covered by plexiglas (sometimes called “Perspex”) which allows UV radiation to pass through to the algae, another third will be covered by plexiglas which blocks out UV radiation, and the final third will remain uncovered (to make certain that we are not affecting the algae by covering them with plexiglas). The algae under the UV transmitting plexiglas will be exposed to a higher dose of UV radiation than they were exposed to at 50ft.
The preparation for this experiment began long before we arrived at Palmer Station, as the carpenters, Jeff and Ryan, had already constructed the racks and substrates. They didn’t have all the fun with power tools though, as we had a few finishing touches to do when we arrived.
Before we could begin to collect and attach the algae we had to transport 15 substrates to our experiment site which is at Kristie Cove, just south of the station. It took two boats and 6 people to accomplish this task, as well as a winch and a lift bag to help lower the substrates into the water. Once the substrates were in place we cleared away some of the surrounding algae (which we have kept to feed the animals in our aquarium room) and they are now finally ready for us to begin the experiment!