Science.-Chilean Patagonia, a haven of giant kelp forests – Publimetro México

Madrid, 3 (European press)

But along the rugged southwest coast of Patagonia, giant kelp is thriving and showing remarkable stability for nearly 200 years. New research suggests that frequent periods of ocean cooling can help keep seaweeds viable.

The researchers found that these giant kelp forests had not experienced an extreme marine heat wave since 1984, and in fact, the area had regular marine cold waves that became more intense.

From 2014 to 2019, the area experienced more severe and colder cold waves compared to the rest of the study period. Glacier melting and increased wind activity could explain these rapid, localized cooling events.

Giant kelp forests are found along a quarter of the coasts from the equator to high latitudes, and are an important species to their ecosystems, which are among the most productive and biodiverse in the world.

Heat waves can cause changes in neighboring species, such as sea urchins and sea otters that eat them in the northern hemisphere; If the otters are gone, hedgehogs can overgraze the kelp forests. Higher sea temperatures can also directly stress seaweeds, as they are better adapted to colder waters.

In central and northern Chile, unregulated direct harvesting by humans is destroying kelp forests. These threats have led to the degradation of many kelp forests in recent decades, resulting in the loss of 2% of kelp forests each year.

Yet the giant kelp forests in Patagonia, in southernmost Chile, look exactly as they did in the early 20th century, according to marine geographer Alejandra Mora-Soto, lead author of the new study, which appears in the Journal of Geophysics. search oceans. In his previous work, Mora Soto compared nautical charts from Charles Darwin’s Beagle voyage to recent satellite images of seagrass and found that little has changed, despite climate change and human influence.

Maura Soto, currently affiliated with the University of Victoria, said in a statement, in British Columbia, but completed this research while at Oxford University.

To find out, Mora Soto and colleagues analyzed sea surface temperatures from the farthest 800 miles of South American coasts from 1981 to 2020. They were looking for marine heat waves and cold waves. While heat waves press on the kelp forests, they question the effect of cold spells.

“The melting of the ice means more cold water entering the ocean environment. This can lead to very short rises in lower temperatures, anywhere from a few days to two to three weeks,” said Mora Soto. Cold water can act as an air conditioner for seaweed, regulating its environment and maintaining comfortable temperatures. He added that wind patterns affecting ocean surface circulation and heat flow, or cold water traveling around Antarctica, could also be factors.

The prospects for kelp forests may remain promising, at least for the foreseeable future. Current climate and ocean models predict that the Southern Ocean, the waters in which thriving kelp forests live, will avoid massive warming. But as snowmelt increases, this fresh water can bring with it sediments that block sunlight, different combinations of nutrients, and even frigid temperatures.

“If there is ice in the system, it can be very stressful for the seaweed,” said Mora Soto. Scientists do not yet have well-defined windows on how long different types of seaweed can withstand frigid waters.

Mora-Soto emphasized the need to protect exceptionally successful kelp forests. “In southern Patagonia, most of the land around the kelp forests is protected, but not necessarily the water,” he said. “And in the northern regions of Chile, kelp forests are used to make alginate, creating underwater deserts in ecologically favorable conditions. I hope that environmental experts, NGOs, local communities and the current government will help make seagrass protection a reality.”