Scientists of several nationalities believe that the detonations and gas jets which took place on September 26, 2022 put to the test a sea already affected by pollution and climate change.
by Anne-Françoise VOIST (Malmö (Sweden), regional correspondent)
Since September 26, 2022 and the explosion of Nord stream gas pipelines, connecting Russia to Germany to the Baltic Sea, Swedish, Danish and German police are carrying out the investigation to try to identify sabotage officials. At the same time, another type of investigation takes place. All around the Baltic, scientists try to assess the environmental consequences of detonations, which have pierced the pipes in four places.
If the risk of a “climatic bomb”, caused by the leak in the atmosphere of at least 70,000 tonnes of methane – a powerful greenhouse gas – was quickly dismissed by the police station Atomic energy and alternative energies (CEA), fears remain concerning the impact of this incident on the ecosystem of the youngest sea in the world, already put to the test by pollution and climate change.
“We could attend a cumulative effect, with much more important consequences than those first anticipated”, summarizes Thomas Dahlgren, marine biologist at the University of Göteborg, in Sweden. Until January 5, for four months, his colleagues and tracked down the traces of methane in the water, using a underwater robot. The first days after the explosion, the levels were a thousand times higher than those usually observed.
“Toxic effect on fish”
Over the weeks, methane concentration has decreased, to get closer to normal after a few months, apart from a few pockets, where the quantities remain high, as well as proximity to the holes caused by the Detonations, “which makes us think that gas continues to escape from gas pipelines”, indicates Thomas Dahlgren.
The high concentration of methane in water could have several consequences. “In its dissolved form, by nourishing bacteria, methane could enter the food chain and participate in eutrophicization [proliferation of algae] of the Baltic Sea”, according to the biologist. Furthermore, combined with the lack of oxygen that rages in the semi-close-up sea, gas could have “a toxic effect on fish”, completes Mr. Dahlgren.
published at the end of January, the results of the analyzes carried out by the Swedish veterinary institute (SVA), out of around thirty cod, taken in mid-October 13 km from one of the explosions, seem to go in this direction. Scientists have indeed discovered an alteration of fish branchies. “The branchial filaments, that is to say the absorbing parts of oxygen, have changed shape,” explains Charlotte Axen, chief veterinarian. “This affects the capacity of fish to absorb oxygen and get rid of the co 2 ,” she said.
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