Written by SEANET Aquaculture Intern, Hallie Arno
Here on Hurricane, we are always trying to find ways to be more sustainable. Often, this happens on land, but many don’t realize that we do this in the ocean as well. One of these projects is growing kelp, which might have benefits for water quality.
As fossil fuels are burned, carbon dioxide gets released into the air. The ocean absorbs this carbon dioxide like a sponge, removing some from the air. While this gives us the benefit of less CO2 in the atmosphere, it also can cause problems for life in the ocean. When carbon dioxide from the air interacts with water, it forms carbonic acid, which leads to ocean acidification. This means that the pH of the ocean will decrease, which makes it difficult for shell-building creatures (such as scallops, clams, and periwinkles) to extract calcium from the water to build their shells.
While shellfish aquaculture is expanding in the Gulf of Maine, ocean acidification is also getting worse. It is already a problem in pacific states where aquaculturists need to treat water to lower the pH before pumping it into their hatchery.
One idea to help remediate ocean acidification that researchers are exploring is called phytoremediation. This means using photosynthesizing organisms (plants or algae) to absorb CO2 from the water. In Hurricane Sound, we can try using kelp—like trees, they absorb CO2 and produce oxygen. Researchers at Bigelow Labs and Island Institute have already found that kelp can affect the amount of CO2 dissolved in the water in the winter when it is growing the fastest. However, shellfish do most of their growth in the summer. Will kelp still have these positive effects when it is warm growing slowly?
To test this, I have been taking daily water samples to test the pH and dissolved oxygen content of seawater around Hurricane Island to see if kelp has any effect on the chemistry of the ocean. I am testing our kelp aquaculture lines, a wild kelp bed off of the dock, and a bed of Ascophyllum nodosum (knotted wrack) in Valley Cove. Stay tuned for the results!