So just in time for Halloween weekend, our class has started terrorizing snails in the name of science!
We started by exposing them to ambient and future carbon dioxide levels, in order to mimic ocean acidification. Changing ocean pH is making the marine world a scary place to be. Increased carbon dioxide in our atmosphere is being absorbed by the ocean, which in turn is leading to the pH becoming more acidic, hence the name ocean acidification.
Increased acidity has lead to a lot of scary things. Organisms that make shells aren’t able to make shells as well as they could previously. Survival of different marine larvae has been decreased. It can even affect an organism’s ability to detect chemical changes in its environment. Which is a big deal. If organisms can’t detect predators or injury of cohorts in the environment… well they won’t last very long. This is what decided this experiment, looking at changes in snail behaviour as a result of change in dissolved carbon dioxide, in response to seastar and crushed conspecific chemical cues.
We set up a lab to look at the black turban snail’s behavioural responses to their sea star predators. We first acclimated snails to different cues (the presence of crushed brethren, sea stars, and the two combined). Then we observed how far they ran away when exposed to predator stimuli (we poked them in the face with sea star limbs).
There’s a number of different things you can measure with this setup; we chose to look at the total and net distance traveled by the snail after it had been poked, as well as the change in angle. We also put the acclimated snails in their respective cue water, and looked at how fast it took them to crawl out of the water.
This is where we come to the trials and tribulations of working with live animals. They have minds of their own, and don’t always want to do what you want them to do. For example, you can’t exactly measure the time it takes to crawl out of the water if the snails are content to go in circles at the bottom of their containers. You also can’t poke them in the face and look at their response if they refuse to come out of their shells.
Even with some uncooperative snails, we still have things to analyze! I haven’t seen any significant trends in our data, but that doesn’t mean it’s over for the snails. Our results have just shown that we have more questions to answer. There is still uncertainty about how behaviour changes in response to ocean acidification, particularly on changes in how organisms interact with one another. Because really, what species do we see that doesn’t interact with at least one other species in its habitat? Species rarely exist alone. I’d love to do more work looking at these kinds of interactions, so more than likely I’m not done terrorizing marine critters. I’ll keep you guys posted on what comes next!