The Inconvenient Truth: Part 2

In our world today, we are producing carbon dioxide through human sources such as factory emissions, and this is resulting in an increase in the overall carbon dioxide levels. This excess carbon dioxide is not only contributing to global warming, but some is being dissolved into our oceans! This increase in carbon dioxide has caused the ocean to acidify- I know, it sounds scary. Although this increase in acidity is not enough to affect us humans (you surfers are safe), it does have an effect on the performance of the marine inhabitants.

Ocean AA

Ocean Acidification
Image Source: http://www.i-fink.com
Ocean acidification has shown a general trend of reducing animal’s performance, whether that be through reducing their growth and reproduction, or how well they can produce a shell. This reduction in activity is important to us because a decrease in performance can result in a decrease in population levels of organisms, which will have an effect on the whole ecosystem! Snails live in the intertidal zone and are susceptible to the effects of ocean acidification, and it would be interesting to see the effect on their performance.

My Study

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The black turban snail trying to flip its shell of its back

Photo Credit: Rohan Bhan
I wanted to see how ocean acidification (reduction in pH) altered the activity levels of the black turban snail as a measurement of their performance. To accomplish this, I created two treatments of different pH, and let the snails acclimate to their surroundings for five days. Then, I proceeded to measure the amount of time it took for them to lift its shell back up off the bottom, its righting time, and their velocity. To measure velocity I placed a tracing sheet of paper below the tank and trace their path for two minutes. Then, matching the path to a piece of string of equal length and measuring the string, I could determine the distance traveled, and from that calculate the velocity.

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Experiment Preparation

Photo Credit: Rohan Bhan

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Experimental Set Up

Photo Credit: Rohan Bhan
Interesting Findings

The snails in the lower pH treatment, which is the one where the effect of ocean acidification is being tested, showed to have decreased activity levels, meaning they took longer to flip their shell from off their back and had a lower velocity than the ambient treatment! This means that our little slow friends are responding to ocean acidification with a decreased performance (didn’t think they could get any slower eh?). Black turban snail population levels could in fact dwindle! The reason for this is because they can possibly be more susceptible to predators as they are less likely to escape them with a reduced activity level! Uh Oh! It would be really interesting to see to what degree ocean acidification affects predation on snails, which could be a possible future endeavor of mine.

For more information on ocean acidification visit:

http://ocean.nationalgeographic.com/ocean/critical-issues-ocean-acidification/

http://www.pmel.noaa.gov/co2/story/Ocean+Acidificatio

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