February 26, 2012 A Day in the Aquarium

It’s been another great day. This morning Julie and I were dive tenders for Maggie and Kate, who were diving off Norsel Point. They collected samples and picked up some substrate plates Kate put out last year; she is interested in seeing what species of organisms colonize them. After lunch everyone was busy in the aquarium, where the Aqua Medic table is set up. The finishing touches on that are coming together nicely.

Kate uses a heat gun to put finishing touches on the Aqua Medic table

I spent much of the afternoon cutting the dividers to fit the microcosms that will go in the Aqua Medic table. As I’ve mentioned, each microcosm will hold 2 different species of algae, 1 species of limpet and 1 species of snail. It’s the dividers that will keep each species separate within each microcosm, while allowing them to be exposed to specific temperature and pH regimes.

Working in the lab to complete the microcosms

While I was in the aquarium today, Dr. McClintock pointed out something fascinating. The snail Julie is studying in her ocean acidification experiment, Margarella antarctica, has a dramatic reaction to sea stars in the aquarium. When it's touched by one of the sea star's tube feet, it extends its muscular foot and flails around so that it can escape. The limpets Julie will study react in a similar, but slower manner. They bunch up their muscular foot and also move away from the sea stars, which are potential predators.

Margarella antarctica (Courtesy of Maggie Amsler)

Odontaster validus, a common Antarctic sea star

Note the tube feet on the underside of this sea star's upper arm

Sea stars use their tube feet for feeding, locomotion and respiration

Studies have shown that animal behavior can be affected by ocean acidification. For example, clownfish (native to the Indian and Pacific oceans) reared in acidifed water can’t recognize the chemical signals that guide them to the tentacles of an anemone, their usual home. Some clownfish have been shown to be attracted to the scent of predators when reared in acidifed water. That is a fatal attraction! Bad news for Nemo...

In a future study, Julie will determine if the behaviors of the snails and limpets are affected by exposure to acidic waters. Behavior will be measured by video taping the animals before and after exposure and a computer program will be used to quantify any differences. I had the opportunity to observe both Margarella antarctica and the limpets reacting to sea stars in the aquarium today. Take a look at this video. It's fascinating to see how both animals react to the sea star's touch. The snail's reaction is much more dramatic, but the limpet's behavior is also affected by proximity to the sea star.

Isn't it amazing?