Perverse climate effect preserving Patagonian marine algae forests

By Ruben Figueroa

Santiago, Aug 17 (EFE).- The forests of algae in Patagonia that British naturalist Charles Darwin described almost 200 years ago remain unchanged since then due to a “perverse” effect of the climate crisis that keeps the ecosystem stable thanks to the cold water melting off nearby glaciers.

The evidence for this has been noted by Chilean geographer Alejandra Mora, who has researched the undersea forests of Macrocystic pyrifera, commonly called “seaweed,” which is an amalgam of algae that can measure up to 70 meters (230 feet) from its subaquatic base to the end of the tendrils that extend all the way to the sea surface.

Using diving techniques, drone flights and satellite imagery, Mora, who performed her work as part of her doctoral research at Oxford University, created the first global high resolution map of this marine plant life and compared it with the first nautical maps of Patagonia that Darwin made.

The well-known British biologist explored a large portion of Chilean and Argentine Patagonia between 1832-1834 on board the HMS Beagle, noting down his observations about land and marine species in the area and, in one of his notebooks, mentioning the undersea forests of seaweed in the southern ocean channels.

Comparing the modern-day map of 309 algae forests located in continental Patagonia, the Falkland Islands and South Georgia Island revealed that the great majority of them are still located in the same places and with the same coverage that they had almost 200 years ago.

The permanence of the algae contrasts with the less encouraging scenario in other parts of the world, where these ecosystems are disappearing due to global warming.

How then is it possible that these marine forests in Patagonia remain intact despite ongoing climate stress?

The co-author of the study, Mauricio Palacios, told EFE that the phemonenon responds to a “perverse logic” caused by climate change whereby southern waters have remained cold despite overall global warming because of the melting of local glaciers, which is occurring precisely because of the increase in global temperatures.

“In Patagonia there is a climate crisis. It’s the zone where there is more glacial ice mass loss due to global warming. And here is where the perverse logic comes in: Since there’s more deterioration of the glacial mass, that water, which is cold, exerts a favorable pressure on these algae, which live in cold environments,” said Palacios, a researcher with the Dynamic Research Center for Marine Ecosystems in High Latitudes (IDEAL) with Chile’s Universidad Austral (UACh).

The water from the glacial melting includes – besides cold, fresh water – a lot of sedimentary material, which prevents the entry of light into the system and helps this gigantic algae species exist without significant complications, added Palacios, who also is the coordinator of the Marine Conservation Program for Chile with the Wildlife Conservation Society (WCS) Chile.

The investigation also suggested other reasons for the ongoing health of the marine algae, including the fact that “the seaweed forests are affixed to the rocks, which move at very slow speeds, geologically, where 200 years is like the blink of an eye,” Mora said.

The seaweed forests grow in the cold waters of Oceania, the Falkland Islands and all along the Pacific coast of the Americas, especially in southern Chile, forming huge areas of submarine forests.

However, the stability found in Patagonia is not present in other spots around the planet where these forests are disappearing, like in Tasmania, New Zealand and along the Australian coast, where the coverage has diminished by at least 95 percent, Palacios said.

In addition, problems along the Pacific coast in the Northern Hemisphere have been reported, with warm water events that are recurring with “unusual” frequency.

“The water is warmer and that results in all kinds of herbivorous animals eating from this ecosystem, (growing) more quickly and needing to eat even more algae,” the researcher said.

Despite the fact that the Patagonian seaweed remains intact, for now, Palacios warned that “there are disequilibriums on other levels,” like the fact that they are suffering from certain “small invertebrates that have problems with the increase in acidification of the oceans and are using these algae as climate refuges because within them the acidification is much less.”

Thus, he said that these forests are a “big green lung of the climate crisis” and issued a call to the Chilean government to “take effective conservation measures” to protect them.

EFE