Ocean Apocalypse

Did you know that human activity could cause an ocean apocalypse? In fact, the burning of fossil fuels and deforestation has caused atmospheric CO2 levels to rise. Since the industrial revolution, 40% of atmospheric CO2 has been absorbed by oceans. By the end of the 21st century, it is projected that ocean acidity will increase by five times! You might suspect that acidic seawater may impact marine life, but have you ever thought that it could also affect humans? Not only can ocean acidification impact marine food webs, but it could also affect services that marine ecosystems provide including the production of seafood. In addition, vital bodily functions, including those that reply on proteins, require an optimum acid level to occur properly. If marine organisms cannot regulate the acid levels of their bodies, these essential functions will be affected.

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Atmospheric CO2 has risen to levels unseen in the last 650 000 years. Oceans are absorbing this CO2, resulting in acidic seawater as indicated by a decrease in pH. (Note: pH is a measure of acidity. Lower pH levels are more acidic. Each whole unit decrease in pH increases acidity by 10 times). Photo credit: The Climate Reality Project (from Feely, R.A. et al. (2006))

For my study, I wanted to model the effects of ocean acidification on the marine snail, Littorina littorea. More specifically, I looked at whether Littorina feeding and predator aversion was affected by different seawater pH treatments: pH 4, 7, and 9. According to previous research, I predicted that Littorina feeding and predator aversion would increase with decreased pH.

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My experimental set up. I had three replicate bottles for every treatment with five Littorina in each bottle. Photo credit: Aysha Ayub 2017

The experimental procedure of my study consisted of me exposing 15 Littorina to each of the three pH treatments for five days. After five days, I recorded whether Littorina, from each treatment, fed on sea lettuce within two minutes. I also determined how many seconds it took for Littorina, from each pH treatment, to emerge from its shell and start crawling in crab cue water.

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My feeding and predator aversion experiments. Photo credit: Aysha Ayub 2017

I found that in acidic seawater, Littorina feeding and predator aversion decreased. In the more acidic treatments, less Littorina fed and took longer to start crawling. The results of my study suggest that marine animals will be affected by ocean acidification. Studies like mine can help us realize the effects of our actions and therefore allow us to design management strategies to offset the negative consequences of increased CO2. However, each of us can also take part in reducing our own carbon footprint. Activities to help us reduce our carbon footprints include walking/biking, reducing our air travel, eating locally-produced foods, and supporting clean energy sources including solar or wind energy. So next time, maybe think twice before driving your car to reduce the chance of an ocean apocalypse!

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