BrainCoral_pHandCO2_Hickerson_Emma_SydneyAustralia_2May2024_Reel4205.mp3

Emma Hickerson [00:00:00] That was an effort to install a very complex instrument on the seafloor, a big package. We installed first an anchor, and we had to figure out how to anchor the system. And then, we put the instrument on to the anchor system.

Emma Hickerson [00:00:18] So that, the logistics of doing that with very experienced, you know, working divers was quite complex, and we had to have really good sea conditions to do that. So, that was a good test of our divers and our equipment on the vessel, because we had to use our A-frame to lower the anchor and safely do it, with divers guiding the placement of the anchor into a sand flat that we identified.

Emma Hickerson [00:00:46] And then we ferried the different components of the equipment down to the seafloor, and then installed the whole structure onto the anchor system.

Emma Hickerson [00:00:57] It was a instrument that was built by a Texas A&M University professor, Dr. Niall Slowey, and it was dedicated to measuring the conditions related to ocean acidification, which is closely related to climate change.

Emma Hickerson [00:01:14] So, the ocean increases in acidity through a series of chemical reactions, by absorbing carbon from the atmosphere in the form of carbon dioxide.

Emma Hickerson [00:01:23] The atmospheric carbon is released through respiration: we're all releasing carbon dioxide, all the living creatures are releasing carbon dioxide. Also through the burning of fossil fuels: so, the more fossil fuels are burned, the more CO2 is in the atmosphere.

Emma Hickerson [00:01:41] And the ocean absorbs, I think, about 30% of the carbon in the atmosphere. So, the more carbon that's released, the more uptake that is required by the ocean.

Emma Hickerson [00:01:54] So, the process is that the carbon dioxide mixes with the water and creates a carbonic acid, which subsequently releases hydrogen ions into the water. This increases the ocean's acidity. And that's what we're measuring when we're measuring pH.

Emma Hickerson [00:02:13] Now, we're not saying the ocean is acidic. It's still more alkaline, but it's decreasing in pH, which is moving to the more acidic side. And there's been a 30% fall in the pH over recent years, and it's predicted to fall. Right now it's about 8.1, and the prediction, with the way we're going, is that it will fall to about 7.7 by the end of the century.

Emma Hickerson [00:02:44] And so, the carbonic acid binds with carbonate ions, which are the building blocks that allow marine organisms to build skeletons. So, that's going to directly affect and influence how corals are able to build skeletons, how mollusks are able to build their shells. And think of oysters: they won't be able to build their shells, in that change scenario. There is a physiological impact to fish called, "acidosis", so it will impact our food supply.

Emma Hickerson [00:03:24] One thing that's interesting to think about is that in the tropical climate, the warmer water can't absorb as much carbon dioxide. So, it's really the colder water climates that are going to be, and are, more susceptible to ocean acidification. There have been impacts already recorded in Antarctic waters.

Emma Hickerson [00:03:46] But we, as managers and researchers, we are monitoring the levels of ocean acidification by taking water samples, putting these instruments in, and doing biological surveys to look at the trends and impact possible migration and adaptation of species.

Emma Hickerson [00:04:06] One of these big, complex things that we can't really do a lot, but we can measure things as managers of the Sanctuary, but also understand, as a community and as a population and species, what we can do personally to change our impacts on a very personal scale.

Emma Hickerson [00:04:25] So, we can make decisions to reduce our carbon footprint that may not look measurable from one person. But, if you look at a community level, or a city level, or a country level, it really does have real-life influence and potential, if you consider the really harsh consequences of a changing environment, climate change and the trickle-down effects of things like ocean acidification.