Finding Solutions to Large Problems in Small Places: An Anecdote on Seagrass

A recent article featured in Forbes Magazine discussed a potential solution to the acidification of the oceans. A portion of the carbon dioxide emitted by humans is continuously dissolved into the ocean, harming oceanic animals. These high levels of carbon dioxide in the oceans decrease the overall pH of the waters as CO₂ gets converted to carbonic acid. Oysters and snails, for example, are more impacted than others since they are shell-building animals that require carbonate to help maintain and grow their shells. The coral reefs are also impacted since they also use carbonate to form their white skeletons. The levels of carbonate, being a base, is being reduced by the overall increase in the acidity of the oceans. If the acidity of the ocean increases too much, the shells of animals, as well as coral reef skeletons will be dissolved.

Luckily, there may be a solution. A study was done by University of California, Davis, in the Bodega Marina Laboratory, has given sufficient evidence on how underwater grasslands may create safe zones for marine life who are vulnerable to the destructive effects of ocean acidification. Underwater vegetation, like seagrass and kelp, works similarly to trees on land since they generate their nutritional needs through photosynthesis. This process removes excess carbon dioxide from the environment, as the vegetation absorbs it. The study that was done involved observing seven seagrass beds along Northern California over the course of 6 years. During these six years, sensors, put both in the seagrass beds and outside the seagrass, were used to monitor the acidity of the seawater. The results of this study found that seawater within these seagrass meadows was 30% less acidic than seawater without seagrass. Their results also demonstrated that seagrass ecosystems can sustain prolonged periods of elevated seawater pH, which is important because for seagrass to be a viable option it needs to maintain lower acidity levels in the oceans for a long period of time. The difference in pH between the sensors in the seagrass and the sensors in the non-vegetated areas can be seen in the figure below.

Adding seagrass into the ocean or restoring the seagrass that is already present is challenging and expensive, but there are big implications to its use. Seagrass is home to many animals, like Dungeness Crab and oysters, which are sources of income for fishing communities and the fishing industry. So, seagrass can benefit both these animals that thrive in the ecosystems made by the seagrass as well as the fishing community that relies on this animal for income. Unfortunately, one-third of the world’s seagrass has been destroyed in the twentieth century by human activity: pollution has affected seagrass by reducing the amount of light that reaches the bottom of the ocean, reducing the seagrass’s ability to participate in photosynthesis. Another issue that affects seagrass is boats since anchors on boats are dragged across the seafloor and if seagrass lies in its way, it too will be destroyed. The destruction of seagrass is two-fold as it both eliminates an important component in removing excess carbon dioxide in the ocean and whenever seagrass dies it releases carbon dioxide back into the ocean. Those obstacles can and have been overcome, though, as Virginia’s Chesapeake Bay has been able to restore 9,000 acres of seagrass. Soon other coastal communities will be attempting to do the same.

References:

https://www.forbes.com/sites/allenelizabeth/2021/04/12/scientists-find-underwater-plants-can-combat-ocean-acidification/?sh=7b2af7215875

Ricart, A. M., Ward, M., Hill, T. M., Sanford, E., Kroeker, K. J., Takeshita, Y., Merolla, S., Shukla, P., Ninokawa, A. T., Elsmore, K., Gaylord, B. Coast-Wide Evidence of Low pH Amelioration By Seagrass Ecosystems. Global Change Biology 2021.

https://www.cruisingguides.com/seadogblog/sea-turtles