Monday, November 19, 2007

Phenomenal Bully Picks on the Sea Snails

Everyone in the scientific community, as well as most of the global community, is aware of a phenomenon sweeping the Earth. Try as they might, skeptics are having a harder and harder time denying the existence of Global Warming and it's utterly detrimental effects. Though the climate is what gets the most attention from society, acidification of our oceans is an aspect that is slowly demanding respect.

Rising carbon dioxide levels means a rising level of dissolved CO2 in the seawater. This creates carbonic acid, which in turn lowers the pH of the ocean. Experiments thus far have looked at direct impacts, like on marine vertebrates and if and how their physiology is being effected. Dr. SimonRundle and colleagues from the University of Plymouth in England, however, decided to look at an indirect effect on the behavior of the animal. Their studies have shown that increasing acidity disrupts the common periwinkle (sea snail)'s defense mechanisms.

Normally, these sea snails respond to predators (crabs) by either thickening their shell to protect against being crushed by a claw, or they practice an avoidance behavior where they crawl out of sight. The shell thickening behavior is thought to be caused by chemical signals emitted by the crab that is detected by the snail.

When Dr. Rundle examined the effect of more acidic water only on shell thickening, the result was null. There was no effect on shell thickening from more acidic seawater alone. However, once crabs were introduced to the experiment,the results quickly changed. The snails in normal water increased their shell thickness when crabs were present, but the snails in the more acidic water did very little thickening or none at all. This shows that the acidity disrupts the behavioral process in some way.

These same researchers found that the snails in the acidic water with crabs present increased their avoidance behavior. This is rather interesting because is seems that there is a trade off present. This is an important find because it shows that unless scientists are looking for behavioral changes and indirect effects, the results of acidification of seawater may go undetected.

This article is from the New York Times Science Section and can be found here.

Posted By: Katie Ensor (9)


At 8:38 PM, Blogger PWH said...

I would be interested to know the physiological changes that the snails go though in the acidic water. I'd like to know how the lower pH actually causes the snails to behave differently. Neat artlicle!



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