New Study Suggests Ocean Acidification Can Cause Diatom Decline

Diatoms are the most significant producers of plant biomass in the ocean, assisting in the transit of carbon dioxide (CO2) from the atmosphere to the deep ocean, and therefore, regulating our climate.

Diatoms were previously considered to benefit from ocean acidification because they rely on silica rather than calcium carbonate to create their shells.

Ocean acidification is a chemical shift in seawater caused by increased CO2 absorption that makes calcification more difficult.

However, scientists have recently discovered that diatoms, a form of plankton, are also affected.

Data from field investigations and model simulations indicated that ocean acidification might significantly diminish diatom populations.

Diatom decline

(Photo : ALEXIS HUGUET/AFP via Getty Images)

While calcifying organisms such as oysters and corals have trouble producing shells and skeletons in more acidic seawater, diatoms have been thought to be less vulnerable to the impacts of ocean acidification a chemical alteration caused by carbon dioxide absorption.

Silica, a combination of silicon, oxygen, and hydrogen, is used as a building ingredient for the shells of the world's smallest diatoms, as per ScienceDaily.

Researchers from GEOMAR Helmholtz Centre for Ocean Research Kiel, the Institute of Geological and Nuclear Sciences Limited New Zealand, and the University of Tasmania have now proven for the first time in a paper published in Nature that diatoms are still under threat.

Researchers coupled an overall investigation of numerous data sources with Earth system modeling for the study.

The findings offered a fresh look at the worldwide consequences of ocean acidification.

This is not beneficial since it causes diatoms to descend into deeper water levels before chemically dissolving and being transformed back into silica.

As a result, this nutrient is exported more effectively to the deep ocean, becoming scarcer in the light-flooded top layer, where it is required to create new shells.

According to the scientists' latest study, this causes a drop in diatoms.

Diatoms produce 40% of plant biomass output in the water and constitute the foundation of many marine food webs.

Over the course of many weeks of studies, the chemical makeup of organic material from sediment traps was assessed as it sank through the water contained in the experimental containers.

When combined with water column data, a precise picture of biogeochemical processes within the ecosystem emerged.

The results of the mesocosm research might be validated using global observational data from the open ocean.

They reveal a decreased dissolution of silicon shells at greater seawater acidity, which is consistent with the meta-analysis results.

The obtained data sets were used to run simulations in an Earth system model to analyze the ocean-wide implications of the observed changes.

Also Read: Certain Fish Species Are Rapidly Evolving to Adapt With Ocean Acidification

Ocean Acidification

Ocean acidification is frequently referred to as "climate change's equally wicked twin," and with good reason as it is a serious and destructive effect of excess atmospheric carbon dioxide that we cannot see or feel since it occurs underwater.

At least one-quarter of the carbon dioxide emitted by coal, oil, and gas combustion does not remain in the atmosphere but dissolves in the ocean.

The ocean has absorbed around 525 billion tons of CO2 from the atmosphere since the beginning of the industrial age, or approximately 22 million tons each day now.

Scientists first assumed this was a positive thing since it leaves less carbon dioxide in the atmosphere to warm the planet.

However, they've recognized in the last decade that the slowing warming has come at the expense of altering the chemistry of the ocean.

When CO2 is injected into salt water, the water becomes much more acidic, lowering the pH of the ocean.

Even though the ocean is vast, enough carbon dioxide may have a significant influence.

Ocean water has gotten 30% more acidic in the previous 200 years, quicker than any documented shift in biogeochemical cycles in the last 50 million years.