Abundant ocean algae help cool Earth

Image: Rowan Smith / Unsplash

A common and abundant type of ocean algae - that gives us the smell of the seaside - also plays a significant role in cooling the Earth’s climate, according to recent research.

Algae are microscopic organisms that live in aquatic environments and use photosynthesis to produce energy from sunlight, just like plants. They produce billions of tonnes of a compound called DMSP in the Earth's oceans, helping in their own survival by protecting against environmental stresses like changes in salinity, temperature, pressure and oxidation.

Importantly, DMSP - dimethylsulfoniopropionate - is the main source of a climate active gas called dimethylsulfide (DMS), which we know as the smell of the seaside. When DMS is released into the atmosphere, oxidation products are emitted that help form clouds which reflect sunlight away from the Earth. This effectively cools the planet.

“Understanding the role of pelagophyceae in DMSP production means we need to rethink how much of this compound is being produced and how it impacts our climate."

Dr Jinyan Wang, Ocean University of China and University of East Anglia

Scientists at the University of East Anglia (UEA) and Ocean University of China (OUC) have now identified pelagophyceae algae as particularly abundant and important producers of DMSP. They suggests that release of DMS release from DMSP is likely higher than previously predicted and emphasises the key role of microbes in regulating global climate.

DMS also acts as a signalling molecule, guiding marine organisms to their food and deterring predators. Their findings are changing our understanding of how these tiny marine organisms impact our climate and our planet.

Professor Jonathan Todd, of UEA’s school of biological sciences, said, “The pelagophyceae are amongst the most abundant algae on Earth, yet they were not previously known as important producers of DMSP. This discovery is exciting because DMSP is an abundant anti-stress compound, food source for other microorganisms and major source of climate-cooling gases.”

Dr Jinyan Wang of OUC and UEA said, “Understanding the role of pelagophyceae in DMSP production means we need to rethink how much of this compound is being produced and how it impacts our climate."

This natural process is essential for regulating the Earth’s climate and is also hugely important for the global sulphur cycle, representing the main route by which sulphur from the oceans is returned to land.

Professor Xiao-Hua Zhang, of OUC’s college of marine life science, said, “By identifying the enzymes involved in DMSP production, scientists can better understand and predict the behaviour of these ecosystem-disruptive, brown-tide-forming algae and their impact on global climate change.”

The researchers say further study of Pelagophyceae algae in their natural environment is needed, as well as more detailed studies on other marine organisms.