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Saya de Malha in the Indian Ocean: Probably the largest seagrass area on earth
Photo: GREENPEACE / via REUTERS
In the middle of the Indian Ocean lies a wonderful shallow water area the size of Switzerland, the Saya de Malha.
500 years ago, when Portuguese sailors sailed the area, they noticed huge green fields of seagrass growing on the seabed.
Today oceanographers and climate researchers are interested in what grows here.
They are probably the largest seagrass meadows in the world.
Seagrasses play a huge role in regulating the oceans.
And what many are not aware of: they have considerable potential in terms of climate protection.
According to studies, one square kilometer of seaweed stores almost twice as much carbon from climate-damaging CO2 as forest on land.
The federal government calculates that around 83 million tons of carbon are bound by seagrass fields every year.
That would correspond to the annual CO2 emissions of all cars in Italy and France.
According to a recent study that was published in the journal Global Change Biology, researchers working with Aurora Ricart from the Bigelow Laboratory for Marine Sciences in Maine at the University of California at Davis came to the conclusion that sea grasses also have a certain buffer against acidification the seas offer.
Seagrass forests brought the pH of US coastal waters to a more tolerable level.
Thus, they mitigate the serious consequences of greenhouse gas emissions.
Because the acidification of the oceans is a side effect of the increasing carbon dioxide content in the atmosphere.
Part of the CO2 is released from the air into the sea, where it causes a chemical reaction that lowers the pH value of the water.
But the study showed that the seagrass fields off the US west coast can raise pH by more than 0.1 units.
This lowers the acidity of the water by around 30 percent and the harmful effects on marine organisms may be reduced.
Unclear data on seagrass stocks
The plants also make other valuable contributions.
In the shallow waters of Saya de Malha, they provide an important ecosystem for marine animals.
They are at the same time a nursery, a protected area and a feeding ground for many species.
In addition, the plants clean polluted water and protect coasts from erosion.
How big the worldwide seagrass areas are, however, has not been conclusively researched.
Estimates by the United Nations Environment Program (UNEP) assume an area of around 300,000 square kilometers, spread over areas on all continents except Antarctica.
But the stocks of seaweed are declining globally.
According to the Unep, humans contribute to the destruction of a soccer field of seaweed around every 30 minutes.
This releases the greenhouse gas again.
"This has an enormous impact on efforts to contain climate change," says Dimos Traganos from the German Aerospace Center.
He is the head of a project developing software to improve seaweed stocks using satellite imagery and other data.
Traganos refers to an older study, according to which the seagrass meadows are declining around the world by around seven percent per year.
But in the meantime the value should have changed.
According to a recent study from the UK, more than 90 percent of the British Isles' seaweed stocks will have disappeared in over a century.
Fisheries contribute to this, but so does pollution of the seas.
So it might be worthwhile to reforest seagrass meadows.
Researchers from Kiel had started a project to explore areas in which the sea grasses would develop particularly well.
The climate would be happy about it.
joe