Ocean algae play an unexpected role in cooling the Earth

A common type of ocean algae plays a significant role in producing a compound that helps cool the Earth’s climate, according to new research. This discovery could reshape our understanding of how these tiny marine organisms impact our planet.

Researchers from the University of East Anglia (UEA) and Ocean University of China (OUC) have identified the bloom-forming Pelagophyceae algae as major producers of dimethylsulfoniopropionate (DMSP).

“The Pelagophyceae are amongst the most abundant algae on Earth, yet they were not previously known as important producers of DMSP,” said Professor Jonathan Todd from UEA’s School of Biological Sciences.

“This discovery is exciting because DMSP is an abundant antistress compound, food source for other microorganisms, and major source of climate-cooling gases.”

The role of DMSP in climate regulation

DMSP is produced in massive quantities by marine microorganisms. It helps these organisms survive by protecting against stresses such as changes in salinity, cold, high pressure, and oxidative stress.

Importantly, DMSP is the main source of dimethylsulfide (DMS), a climate-active gas known for its distinctive seaside smell.

“When DMS is released into the atmosphere, its oxidation products help form clouds that reflect sunlight away from the Earth, effectively cooling the planet,” explained study first author Dr. Jinyan Wang.

This natural process is vital for regulating the Earth’s climate and plays a key role in the global sulfur cycle by returning sulfur from the oceans to the land.

Earth’s climate: Microbes and algae

The study suggests that DMSP production, and consequently DMS release, is likely higher than previously estimated. This underscores the crucial role microbes play in regulating the global climate. DMS also acts as a signaling molecule, guiding marine organisms to their food and deterring predators.

Professor Xiao-Hua Zhang from OUC’s College of Marine Life Science emphasized the broader implications of the research.

“By identifying the enzymes involved in DMSP production, scientists can better understand and predict the behavior of these ecosystem-disruptive, brown-tide-forming algae and their impact on global climate change,” noted Professor Zhang.

“This study has also raised questions about other unidentified enzymes or entirely different pathways for making DMSP that are currently unknown.”

Importance of Earth-centric research

The researchers highlight the need for further study of Pelagophyceae algae in their natural environment.

More detailed studies on other marine organisms – as well as better measurements of environmental DMSP levels and the abundance of enzymes involved in making DMSP – are all critical for advancing this field.

This study not only enhances our understanding of Earth’s climate regulation processes but also opens up new avenues for research into the role of marine microorganisms in climate dynamics.

More about Pelagophyceae

Pelagophyceae is a class of algae that belongs to the division Ochrophyta, which is part of the broader group of chromalveolates.

These algae are primarily marine and are found in various ocean environments. They are notable for their small size and unicellular nature, often existing as free-floating cells in plankton.

Ecological role

Pelagophyceae are significant contributors to marine ecosystems, playing a crucial role in primary production and serving as a food source for various marine organisms.

They possess chlorophylls a and c, along with fucoxanthin, which gives them a characteristic golden-brown color.

This pigmentation is essential for their photosynthetic processes, allowing them to efficiently absorb light energy in the ocean’s varying light conditions.

Brown tides

One of the well-known types of ocean algae within Pelagophyceae is Aureococcus, which has been associated with harmful algal blooms known as “brown tides.”

These blooms can have detrimental effects on marine life, including fish and shellfish, by depleting oxygen levels in the water and releasing toxins.

Research into Pelagophyceae has been ongoing to better understand their potential impacts on marine environments, especially in the context of climate change and ocean health.

The ocean and climate connection

The relationship between the ocean and climate is integral and complex, with the two systems deeply interconnected. The ocean acts as a massive heat reservoir, absorbing solar energy and redistributing it around the globe through currents. This heat distribution plays a crucial role in regulating global climate patterns.

Ocean currents

One of the primary mechanisms through which the ocean influences climate is the movement of ocean currents. These currents transport warm water from the equator toward the poles and cold water from the poles back toward the equator, balancing temperature differences across the planet.

For instance, the Gulf Stream in the Atlantic Ocean carries warm water northward, contributing to milder climates in Western Europe.

Atmosphere and weather patterns

The ocean also interacts with the atmosphere, exchanging heat, moisture, and gases. This interaction drives weather systems and influences climatic conditions.

For example, El Niño and La Niña phenomena, which are characterized by periodic changes in sea surface temperatures in the central and eastern Pacific Ocean, have widespread effects on weather patterns, causing variations in precipitation and temperature globally.

The study is published in the journal Nature Microbiology.

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