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Ocean Acidification and Climate Change

Madison Pascual Munar has a Doctorate degree in Molecular Biotechnology.


When you hold a seashell to your ear, can you hear the sound of the ocean?

When we were young, most of us were marveled by the sound of waves we hear once we put our ears close to a seashell. We ask ourselves and come to a conclusion that what we hear is the sound of waves recorded in the shell. We then ask our playmates to do the same and they, too, are marveled. Now, as grown-ups, we found scientific explanations about this, that the sound of the ocean we hear from a seashell is actually the sound of the environment resonating within the cavity of the shell.

As I wrote this essay and started reading about the state of corals amidst climate change, I was fearful that we are about to lose them.

We already know the effects of excessive carbon dioxide in the atmosphere, however, little is known about its effects on the ocean.


Corals on the Brink of Extinction

Corals are marine organisms that build ocean reefs which serve as the rainforests of the seas. Like the rainforests in land, coral reefs also provide a plethora of life-sustaining services such as breeding grounds for fishes, nutrient cycling, and source of food and medicine to man. However, unlike rainforests which can be rehabilitated through reforestation, the destruction of coral reefs is irreversible and environmentally alarming.

Corals utilize dissolved carbon dioxide in the ocean to manufacture their exoskeleton made entirely of calcium carbonate. Unfortunately, corals are also the first organisms on Earth that suffers from the devastating effect of climate change. Even a slight increase in the ocean temperature by one degree will put corals on the brink of extinction.

Coral bleaching is the direct effect of an abrupt change in the ocean temperature. When the temperature of the sea has risen, shallow coral reefs that thrive in a certain range of optimal temperature will be forced to expel its zooxanthellae, the colorful plant-like structure in corals which is a symbiotic association between corals and algae that provides corals its energy through the process of photosynthesis. When the zooxanthellae were expelled from the corals, it will starve and eventually die, leaving the dead white exoskeleton behind. Coral bleaching is irreversible and once the coral is bleached it will never be brought to life again.

Another threat to coral survival is ocean acidification brought also by the increased carbon dioxide in the atmosphere. The excess carbon dioxide is being absorbed in the ocean resulting in increased hydrogen ion concentration in the seawater. Reef-building corals are being decalcified and being dissolved as a result of ocean acidification. When corals die out, fish stocks will collapse and the marginalized coastal communities will suffer from food shortage.

The phenomenon coined as coral bleaching is a concrete evidence that climate change could bring chaos to life's existence on Earth.


Future Energy from the Ocean

Seaweeds or macroalgae are abundant and widespread in the ocean. It is used mainly to produce a gelling substance for food and cosmetics. Seaweeds unlike plants thriving in terrestrial environment do not have lignin. Seaweeds lacking lignin can be directly converted into ethanol without further pretreatments thus rendering its use to be economical.

By virtue of the photosynthetic machinery of macroalgae, these organisms also aid in carbon sequestration by utilizing sunlight and carbon dioxide to build their biomass.

On top of these advantages, the use of seaweeds for ethanol production does not require the use of arable lands which is a major debate in using corn and switch grass for bioethanol production. Seaweeds can be grown either in saltwater or freshwater environment, thus encompassing the conflicts of land-use for food crops.

Biofuel from seaweeds is a viable alternative to fossil fuels. Aside from offering a clean source of energy, it is also sustainable.


If seashells could only talk about ocean acidification, what do you think will they whisper in our ears?

Man has significantly altered the equilibrium of carbon dioxide concentration in the ocean chemistry. Ocean acidification is now playing havoc to marine biodiversity. The extinction of corals will have a domino effect on the survival of other marine animals dependent on coral reefs, and also this will trigger the worsening of poverty and hunger for billions of people living on coastal communities.

At present, there is no effective measure to prevent ocean acidification. Corals are sessile animals, they do not have legs to run and arms to defend themselves from the decalcifying effect of carbon dioxide. These animals will be gone in a blink of an eye if we continue to act deaf and blind on the rising challenge of ocean acidification.

The sound that we hear when we put our ears close to a seashell may not be the real sound of the ocean. A sound that we can also reproduce using our both hands closed together and placed near to our ears. I hope that this scintillating experience will reach the future generations.

Let us not wait that one day these calcareous organisms will become displays in museums and the sound that we once marveled upon will be reminisced using only our bare hands.