This is Jim Fiorendino, your host for On the Ocean. Often when we hear the word hurricane, we associate it with physical destruction caused by flooding and strong winds from these storms. However, something we might not think about is the dramatic changes in coastal water chemistry that can also occur because of these storms. These changes in turn can have significant impacts on animals that live in these environments, like oysters.

<figure class="aligncenter is-resized"><figcaption>Larval oyster growth in supersaturated (left) and undersaturated (right) water. Green arrows indicate dissolution features (Barton et al, 2015). </figcaption></figure>

The oyster reefs in Galveston Bay provide a number of important services by supporting fisheries, providing coastline protection, and naturally filtering water. Oysters prefer to live in slightly salty environments and have a hard time surviving in fresh water for more than a few days. In 2017 Hurricane Harvey released an immense amount of rain which drained directly into Galveston Bay, making the bay almost completely fresh for up to two weeks, which killed a lot of the oysters.

<figure class="aligncenter"><figcaption> Buoy salinity versus date. The landfall of the hurricane is noted by the black line. Trin and Morg represent buoys located near freshwater sources; Midg is in the middle of the bay; Boli is at the mouth.
(Texas Water Development Board) </figcaption></figure>

The recovery of these oyster reefs is at least partly dependent on whether or not the water chemistry supports shell formation. Oysters create their shells from calcium and carbonate, the same elements that make up limestone, and their ability to create these shells is dependent on the chemistry, including the acidity level and the amount of carbonate in the water. The work conducted by scientists at Texas A&M demonstrated dramatic changes in the chemistry of Galveston Bay following Harvey, including significant acidification and a decrease in carbonate concentration, that may make it harder, if not impossible, for oysters, particularly baby oysters, to create their shells. This in turn may threaten the recovery and future of this critical ecosystem, demonstrating just how important these chemical changes caused by hurricanes actually are.

This has been On the Ocean, a program made possible by the Department of Oceanography and a production of KAMU-FM on the campus of Texas A&M University in College Station. For more information and links please go to ocean.tamu.edu and click On the Ocean. 

Script Author: Tacey Hicks

Contributing Professor: Dr. Kathryn Shamberger

Editor: James M. Fiorendino

Featured image from: https://ktswblog.net/2013/12/04/rebuilding-the-texas-oyster-reef/