Carin Bondar is a biologist, TV host and science communicator with a PhD in population ecology from the University of British Columbia. She blogs for Scientific American and Huffington Post and has appeared in a scientific capacity on various international television networks. Her writing has been featured online at National Geographic Wild, Jezebel, Forbes, The Guardian, The Daily Beast and the Richard Dawkins Foundation. Find Dr. Bondar online, on twitter or on her Facebook page. Look for her blogs on science topics in the coming weeks on the David Suzuki Foundation website.
I recently had the pleasure of attending the 2012 American Association for the Advancement of Science meeting in Vancouver, B.C. Among the largest gatherings of scientists from all corners of the globe, this year's conference saw coverage of a wide variety of topics. Cutting-edge science was presented in areas from medicine to physics, and environment to communication. As a biologist, I chose to attend sessions that focused on animal behaviour and ecosystem health. I especially enjoyed the session on ocean acidification. It was presented by leading experts from several universities, each addressing the topic from a different perspective. Much fascinating work is taking place in this area, and I'll be discussing the latest results and trends in subsequent posts here on the Healthy Oceans Blogs. However, I'd like to begin my coverage by providing a general introduction and clarifying some common myths about ocean acidification.
Sign up for our newsletter
What exactly is ocean acidification?
It's no secret that mean levels of atmospheric CO2 are significantly higher than they have been on our planet for the past 600,000 years. Burning fossil fuels is the largest contributor to the rise, and all of this "extra" carbon dioxide in the atmosphere is having many effects all over the planet. Approximately 25 per cent of atmospheric CO2 is absorbed by the surfaces of the world's oceans, and the resulting change in pH is what scientists have termed ocean acidification. To be clear: the term acidification is not meant to describe a future ocean that is composed of acid as opposed to water. The shift in pH from historic levels of 8.25 to predicted levels of 8.14 and lower is movement toward the acidic end of the pH spectrum; however, it is far from the level of something like lemon juice (with a pH of 2.4). Despite the fact that sea life will not be subjected to living in actual acid, the change (which is measured on a logarithmic scale and therefore represents a 100 to 150 per cent decrease in ocean pH) will have massive implications.
Winners and losers
According to Christopher Harley at UBC, some organisms will fare better than others in an acidified ocean: some will be clear winners, others losers. Researchers are racing to identify which organisms will be hit hardest by these environmental changes. Animals that have calcareous shells are in big trouble. For example, molluscs like mussels, clams and snails secrete their own shells by drawing on calcium carbonate in the seawater. Hard corals and sea urchins do the same to construct their skeletons. Due to a sequence of fairly simple chemical reactions, calcium carbonate is not as bioavailable in an acidified ocean. Quite simply, organisms that require it for skeletal or shell formation during development are going to suffer drastic consequences.
Why does this matter?
Your initial reaction may not be one of complete alarm. Large animals tend to rule when it comes to tugging on our heartstrings, and a mussel isn't exactly a polar bear or an orca. However, the potential for changes to ecosystem functions is massive. For example, mussel beds provide habitat to hundreds of marine species and food for many marine and terrestrial predators. Sea urchins are a major component of the diet of seals and sea lions, and hard corals provide a subtidal home to countless fish and invertebrates. Moving a few steps up the food chain we will undoubtedly see that orcas and other top predators will be affected by ocean acidification too.
In a subsequent post I'll look at some complex predictive modelling being undertaken at the National Oceanic and Atmospheric Administration in the U.S. that is providing insight into how these changes will reverberate through oceanic food chains. For now, suffice it to say that due to ocean acidification, aquatic ecosystems in 2112 will look substantially different than those of today.