Underwater gardeners plant seaweed to save ‘dead’ Danish fjord

Under a white tent on the shore of a polluted Danish fjord, volunteers and researchers prepare slender green shoots of seagrass to be planted on the seabed to help restore the local damaged ecosystem.

Denmark generally has a good environmental record, but only five of the 109 coastal zones are considered healthy, according to the Danish Environmental Agency.

Like other coastal areas in Denmark, the Vejle Fjord suffers from eutrophication – a process in which nutrients, often from runoff from land, accumulate in a body of water and lead to increased growth of microorganisms and algae.

The algae cover the water surface, blocking light and cutting off oxygen, leading to the death of plants and animals.

An underwater surveillance camera installed by the municipality in the Vejlefjord last year discovered only one fish in 70 hours.

– “Completely collapsed” –

In Denmark, a major pork producer, more than 60 percent of the country’s land is used for agriculture – one of the highest concentrations in the world. As a result, there have been repeated warnings about the danger of erosion in recent years.

A 2022 report by the University of Southern Denmark (USD) concluded that the 22-kilometer-long Vejle Fjord was in a “poor ecological condition” due to high nitrogen runoff from fertilizer use on farms.

And as the mercury rises, so do the problems.

“We had a very warm summer in 2023 and that led to a huge lack of oxygen,” Mads Fjeldsoe Christensen, a biologist working for the municipality of Vejle, told AFP.

“It was pretty bad. We saw a lot of dead fish.”

He noted that “over the last 30, maybe 40 years,” excessive amounts of nutrients have entered the fjord.

“The fjord was able to recover for a long time. But for about three or four years now we have been experiencing a fjord that has completely collapsed.”

Scientists and the community decided in 2018 to reintroduce the slender green seagrass to the busy bay in hopes of restoring the once lush seabed and the wildlife that thrived on it.

One recent weekend in Vejle, around 50 volunteers were on hand to help the scientists.

Despite the dull, stormy weather, they crowded around tables with buckets full of seagrass shoots that the scientists had picked in areas where the plant grows well.

The volunteers rolled the individual shoots around biodegradable nails, which divers then removed and transplanted into the seabed.

“All the fish grow up in the seagrass, so it’s like a kindergarten for fish life,” said Fjeldsoe Christensen.

“If there is no seagrass, there is simply no room for the fish population to develop.”

– “Funeral” at Vejlefjord –

Since replanting began in 2020, six hectares of seabed and more than 100,000 seagrass shoots have been planted on the seabed.

In some places, divers have observed a return of aquatic life such as crabs and fish.

“We are seeing the effects of restoring nature,” said SDU biologist Timi Banke, who is participating in the project.

In April, Greenpeace organized an open-air “funeral” for the Vejlefjord to draw attention to the dire state of Denmark’s coastal waters.

“It is in bad shape and that is why we are doing something, but it is not dead,” Banke told AFP, praising the efforts of environmentalists and locals.

On World Oceans Day on June 8, the Danish think tank Ocean Institute organized seagrass transplants at 32 locations across the country.

“By planting seaweed, we focus on restoring nature, but that does not mean we should forget that we also need to reduce nutrient emissions into polluted Danish waters,” the think tank’s director, Liselotte Hohwy Stokholm, wrote on the organization’s website.

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