This bay in Scandinavia has world record in carbon storing

January 12, 2017

Forests are potent carbon sinks, but also the oceans' seagrasses can store enormous amounts of carbon. A little bay in Denmark stores a record amount of carbon. Here is the secret.

Seagrass plays a bigger role in the Earth's carbon cycle than most of us think. The underwater meadows of seagrass are capable of storing large amounts of carbon - a talent that draws attention in a time, where decision makers and scientists are searching for ways to bring down the release of CO2 to the atmosphere.

Efficient meadows of carbon storing seagrass are found in coastal areas in many parts of the world. But according to biologists one particular meadow in Denmark is by far the most efficient.

The meadow is situated in the bay Thurøbund on the island Thurø in the South Funen Archipelago, Denmark.

Special conditions in this bay

- Many seagrass meadows in the world have been investigated. Recently I was part of investigating and measuring carbon storing capabilities of 10 seagrass meadows in the Baltic Sea. No place comes even close to Thurøbund, says Professor Marianne Holmer, University of Southern Denmark (SDU).

Professor Holmer is head of SDU's Department of Biology and she is an expert in seagrass ecology and biogeochemistry.

The explanation is found in the special conditions in Thurøbund.

Protected and productive

- It is a very protected bay - and also very productive. So the seagrass thrives and when the plants die they stay in the meadow. They are buried in the sediment and in this process their content of carbon gets stored with them. In Finland the seagrass grows in open coast areas, which means that the dead plants much more often are washed off to sea, taking the carbon with them. Once the carbon has been taken out to the sea it is unsure what happens to it, says Professor Holmer.

Thurøbund stores ca. 27,000 grams of carbon (gC) pr. square meter. This figure has never been measured to be more than 10,000-11,000 gC pr. m2 in other parts of the world.

According to the new study Danish seagrass meadows store 3-4 times more carbon than Finnish meadows.

Harsher environment in Finland

The study's lead author is PhD student Emilia Röhr, University of Southern Denmark and Åbo Akademi University in Finland. Co-authors are Marianne Holmer and Christoffer Boström from Åbo Akademi University. The study has been published in Biogeosciences.

- The Finnish meadows in our study are more exposed than the Danish and they grow in harsher environments where the dead plants do not sink to the bottom, so their carbon content does not get stored in the sediment, explains Emilia Röhr.

It is unknown where the dead seagrass plants go and what happens to them, when they get washed out to the open sea. Maybe their carbon gets stored elsewhere, maybe it ends up as CO2 in the atmosphere.

The economic value

Due to the carbon storing efficiency of seagrass meadows, a system has been designed to calculate the economic value of their stored carbon.

- The value in Denmark is 1809 Euro pr. hectar while in Finland it is 281 Euro, says Emilia Röhr.

Other scientists have calculated that the global loss of seagrass equals 1.9 - 13.7 billion US dollars in lost carbon storing.

Fish and shrimps need seagrass

Many countries have a focus on restoring lost seagrass meadows. The meadows are not only good at storing carbon: they are also home for many small and large animals, including commercially important species as shrimps, cod and flatfish.

The plants also function as particle filters, keeping the water clear.

On a global scale Earth has lost estimated 29 pct. of its seagrass meadows since 1879. Danmark has lost 80-90 pct. since the 1930s.

Blue carbon

The worlds' oceans store vast amounts of carbon, especially in coastal areas like mangrove forests, seagrass meadows and salt marshes. This is called blue carbon, and the mechanisms are the same as when land forests store carbon. Seagrass meadows cover only 0.1 - 0.2 pct. of the worlds' seafloor, but they account for storing of up to 18 pct. of all ocean stored carbon. The meadows in the Baltic Ocean store 1.7 - 12 pct. of all seagrass meadow stored carbon in the world.

Seagrass is a plant

Seagrass is not a seaweed, but a plant with flowers, leaves and roots just like plants on land. It also produces seeds, which is spread on the seafloor and grow to new plants. There are ca. 60 seagrass species in the world. In Denmark eelgrass (Zostera marina) is the most common. Seagrass needs light and only grows in shallow water. They need min. 10 pct. of the sun's light.
Professor, Head of Department of Biology, Marianne Holmer. Phone:+45 60112605.

University of Southern Denmark

Related Carbon Articles from Brightsurf:

The biggest trees capture the most carbon: Large trees dominate carbon storage in forests
A recent study examining carbon storage in Pacific Northwest forests demonstrated that although large-diameter trees (21 inches) only comprised 3% of total stems, they accounted for 42% of the total aboveground carbon storage.

Carbon storage from the lab
Researchers at the University of Freiburg established the world's largest collection of moss species for the peat industry and science

Carbon-carbon covalent bonds far more flexible than presumed
A Hokkaido University research group has successfully demonstrated that carbon-carbon (C-C) covalent bonds expand and contract flexibly in response to light and heat.

Metal wires of carbon complete toolbox for carbon-based computers
Carbon-based computers have the potential to be a lot faster and much more energy efficient than silicon-based computers, but 2D graphene and carbon nanotubes have proved challenging to turn into the elements needed to construct transistor circuits.

Cascades with carbon dioxide
Carbon dioxide (CO(2)) is not just an undesirable greenhouse gas, it is also an interesting source of raw materials that are valuable and can be recycled sustainably.

Two-dimensional carbon networks
Lithium-ion batteries usually contain graphitic carbons as anode materials. Scientists have investigated the carbonic nanoweb graphdiyne as a novel two-dimensional carbon network for its suitability in battery applications.

Can wood construction transform cities from carbon source to carbon vault?
A new study by researchers and architects at Yale and the Potsdam Institute for Climate Impact Research predicts that a transition to timber-based wood products in the construction of new housing, buildings, and infrastructure would not only offset enormous amounts of carbon emissions related to concrete and steel production -- it could turn the world's cities into a vast carbon sink.

Investigation of oceanic 'black carbon' uncovers mystery in global carbon cycle
An unexpected finding published today in Nature Communications challenges a long-held assumption about the origin of oceanic black coal, and introduces a tantalizing new mystery: If oceanic black carbon is significantly different from the black carbon found in rivers, where did it come from?

First fully rechargeable carbon dioxide battery with carbon neutrality
Researchers at the University of Illinois at Chicago are the first to show that lithium-carbon dioxide batteries can be designed to operate in a fully rechargeable manner, and they have successfully tested a lithium-carbon dioxide battery prototype running up to 500 consecutive cycles of charge/recharge processes.

How and when was carbon distributed in the Earth?
A magma ocean existing during the core formation is thought to have been highly depleted in carbon due to its high-siderophile (iron loving) behavior.

Read More: Carbon News and Carbon Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to