Seaweed- a Solution to Ocean Acidification

The problem: Ocean Acidification

Ocean acidification is caused by an increase in carbon dioxide concentration in the ocean. The main source of CO2 in the atmosphere is due to carbon emissions and deforestation. The ocean water absorbs around 25% of CO2 found in the atmosphere. As picture 1 illustrates, the absorbed CO2 reacts and produces carbonic acid. The carbonic acid then causes a decrease in carbonate ions and an increase in H+ ions. Carbonate ions are used by many marine species to build their shells and skeletons, hence by decreasing the amount of carbonate ions available many shellfish and marine life are not able to deposit as much calcium in their shells; shellfish and marine hurt from the decrease in carbonate ions. An increase in H+ ions leads to lowering the ocean’s pH or causing ocean acidification.

Picture1: Carbon dioxide absorption into the ocean



The solution: Seaweed – Kelp

Bren Smith, an “ocean farmer” believes that kelp farming is the future. He called seaweed, more specifically, kelp, the trees of the ocean. This is because like most plants on land pull CO2 from the atmosphere, seaweeds and kelp pull out CO2 out of the water. The seaweed then uses the CO2 to ease photosynthesis, as pictured in picture 2, and releases O2.

Picture 2: Seaweed, CO2 absorption


Bren Smith and his group plant kelp in rows in certain lots of the ocean. They use yellow buoys to measure how water changes as it flows through the kelp field and seeing if baby shellfish grown with the kelp do better at building their shells. However, results will not be available for another year. But he and his team are hopeful that they will see positive results from the effects of the kelp, such as stronger shells on shellfish and less acidic water. However, kelp/seaweed is not the only thing Bren Smith and his group farm. They use the same ocean surface area but he stacks his produce. As shown in picture 3, the Smith group farms scallops, mussels, oysters, clams and seaweed.

Besides the positive environmental impact of seaweed in the ocean, seaweed can also be a source of food, since it is rich and calcium, fiber, iron, and anti-oxidants.

So seaweed could be new super food of the future.

Picture 3: More than just Seaweed farming




5 thoughts on “Seaweed- a Solution to Ocean Acidification

  1. Good afternoon Ms./Mrs. De Loera,

    My name is Maria Tu, I am a student at San Diego Miramar College, I am writing a solution journalism piece on Ocean Acidification and was hoping you can answer a few question if you have time.

    – Are there any negative effects to this solution?
    – Are there any obstacles getting in the way of this solution?

    Thank you for your time.


    • Seems like one drawback is converting wild coastal ocean areas to “farmed” areas, with visible buoys and other non-natural underwater objects.
      To impact ocean pH, you would need to increase the total amount of seaweed growing in the ocean, and this is usually controlled by certain limiting nutrients (such as nitrogen or phosphorus). Adding these nutrients could trigger the growth of undesirable organisms such as algae.

  2. Thank you for this brilliant piece Miss De Loera. Can’t wait to read up on your further research on Kelp the superfood !

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