A Surprising Discovery Under the Ocean: "We Have Ignored Them for Years"
When thinking about fungi, one usually imagines them in a forest, on trees, or in the ground. However, it turns out that fungi also live under the sea, and a new study published in the scientific journal "PLOS Biology" points to their surprising role: they may help store carbon on the ocean floor. Researchers discovered that tiny fungi in the Arctic region absorb substances from the environment.
When thinking about fungi, one usually imagines them in a forest, on trees, or in the ground. However, it turns out that fungi also live under the sea, and a new study published in the scientific journal "PLOS Biology" points to their surprising role: they may help store carbon on the ocean floor. Researchers discovered that tiny fungi in the Arctic region absorb substances from the environment and use them for growth, thereby leaving some of the carbon in the seabed instead of it returning to the environment as carbon dioxide.
The study was conducted in Kongsfjorden, a fjord in Norway located in the Arctic region. A fjord is a narrow and deep bay usually surrounded by mountains, and in this case, it is a very cold region also affected by glaciers. The researchers collected samples from the seawater, the fjord floor, and the nearby land. The goal was to understand what tiny creatures live there and what happens to carbon-containing substances after they reach the bottom. Among the creatures found were microscopic fungi — too small to be seen with the naked eye.
Carbon is found in many substances in nature and is constantly moving between living creatures, the soil, the oceans, and the atmosphere. Some of it can be released into the air in the form of carbon dioxide. The researchers discovered that fungi on the seabed absorb organic substances dissolved in their environment. These substances contain, among other things, carbon and nitrogen.
Instead of all the carbon in them being released back into the environment, the fungi use some of it to build their bodies and grow. Simply put, some of the carbon becomes part of the fungus and remains on the seabed. This is why the researchers believe that fungi may contribute to carbon storage in Arctic regions.
Until today, bacteria were attributed a particularly central role in the decomposition and consumption of dissolved organic substances in the sea. The new study shows that the picture is more complex. In some of the samples tested, the fungi were able to absorb these substances very efficiently, and even outperformed bacteria and other microscopic creatures.
The researchers also noticed something else: when fungi were more dominant in consuming organic matter, less carbon dioxide was emitted compared to samples where the activity of bacteria and archaea was more significant. The extent of the activity also surprised the researchers. More than 80 different types of fungi were found to be involved in the uptake of amino acids — organic substances that serve as basic building blocks for living creatures. 34 of the types found belonged to a group of water fungi of the genus Alatospora. In contrast, only seven types of fungi were found in the soils near the fjord that participated in the process tested.
The researchers wanted to know if the fungi were capable of continuing to function even when there was not much oxygen in their environment. In experiments, it turned out that they continued to absorb amino acids efficiently even in low-oxygen conditions. Fungi of the genus Alatospora were particularly prominent in this ability. This figure is significant because under the fjord floor, oxygen disappears quickly: already at a depth of a few millimeters, conditions can be created where there is almost no oxygen.
Fjords in the Arctic region are places where large amounts of carbon are stored within the sediments under the seabed. According to the researchers, more than 10% of all carbon buried under the ocean floor is found in environments of this type. Until now, the role of fungi in the process was almost not taken into account. The new study suggests that these tiny creatures may be one of the factors that help keep carbon on the seabed for a long time. However, the researchers still need to check how significant the process is on a large scale and in other regions of the world.
The problem is that the discovery comes at a time when the Arctic region is undergoing rapid changes. The researchers fear that the ecosystems in the region are changing even before science has managed to understand how they function. According to researcher Juan Carlos Trejos-Aspelta, "The Arctic is changing before our eyes at an unprecedented rate."
The study shows that in order to better understand what happens to the carbon that enters the oceans and how much of it remains on the seabed, scientists will have to take into account creatures that until now have received almost no attention — the microscopic fungi that live under the sea.
