Hidden underwater forests that could help tackle the climate crisis | oceans

Bubbles flow furiously behind Frank Hurd as he gently cuts through the curtains of giant kelp. Ribbons of green and gold stretch upward across the cool waters of the Pacific Ocean toward the sun.

Heard, a marine biologist with The Nature Conservancy, dives into a kelp forest off Anacapa Island, one of the protected rocky volcanic islands that make up the Channel Islands National Park, an archipelago off the coast of Southern California.

This thick, healthy algae — a type of seaweed — makes up a small part of the underwater forests that cover the coastline of nearly every continent. Some of them have been relatively well studied, including the Great African Sea Forest, a lush stretch of giant bamboo grass that spreads north from Cape Town to the Namibian coast that was the setting for the movie My Octopus Teacher; and the Great Southern Reef, a giant forest of kelp that hugs Australia’s southern coast. But many of these forests are little known and unknown – hidden under the water.

Harbor seals descend from the kelp canopy in the rich underwater forests off Santa Barbara, California.
Harbor seals descend from the kelp canopy in the rich underwater forests off Santa Barbara, California. Photo: Douglas Kluge/Getty Images

Despite being one of the fastest growing plants on Earth, kelp has historically been difficult to map due to the difficulties of satellite bathymetry. However, search published In September I found the seagrass forests to be much more extensive than previously expected.

An international group of scientists from eight countries, led by Dr Albert Pessarrodonna of the University of Western Australia, hand-screened hundreds of studies – including local plant data records, online repositories and citizen science initiatives – to model the global distribution of ocean forests. They found that the underwater forest covers between 6 and 7.2 million square kilometers – an area comparable to the Amazon rainforest basin and twice the size of India.

It is still my octopus guru
Still image from My Octopus Teacher, located in a lush stretch of giant bamboo spreading north from Cape Town to the Namibian coast. Image: Netflix

Seagrass forests could act as a vital buffer against the climate crisis, absorbing carbon dioxide from seawater and the atmosphere. May ocean forests Store more carbon as the Amazon rainforest, according to one analysis.

However, there is still a significant gap in understanding the long-term ability of seaweeds to sequester carbon, as they lack a root system to trap carbon in the ground, unlike Other marine plants such as mangroves and seaweed. Whether the carbon stays locked up also depends on what happens to the seagrass, and what remains there Scientific discussion About how effective it is at storing the item.

Fish in a kelp forest
Kelp provides food and shelter for fish, marine animals, and birds. Photo: Brandon Cole Images/Shutterstock

Marine ecologist Dr. Karen Phillipe-Dexter, one of the 10 study authors, said the research was a “major step forward” in understanding the potential role seagrasses could play in mitigating climate collapse, “because it calculates productivity – growth and carbon uptake – as greater than Marine plant ecosystem”. It could also help estimate the carbon sequestration potential of the world’s marine forests, she added.

Kelp, the largest species of seaweed, capable of growing tens of meters in height, also plays a vital role in marine ecosystems, providing food and shelter for fish, other marine animals, and birds.

In Australia, the native kelp is home to Herbal saddles – a purple-colored creature with leaf-like appendages that resemble kelp’s fronds – it only lives along the country’s coast. Kelp forests along the Pacific coast of North America provide vital habitats for southern sea otters. In addition, the powerful gray whale uses kelp forests as a refuge from predatory killer whales and as a vital feeding ground for their young as they migrate to Alaskan waters from Mexico’s Baja California.

Grassy sea dragon in Jervis Bay, New South Wales, Australia.
Grassy sea dragon in Jervis Bay, New South Wales, Australia. Photo: Wildestanimal/Getty Images

Flooded forests could also have a role in efforts to alleviate the world’s food security crisis, thanks to their rapid growth.

Scientists examined hundreds of individual studies from around the world in which seaweed growth was measured by divers. “Ocean forests are more productive than many intensively cultivated crops such as wheat, rice and maize,” the study noted. It defined productivity in terms of the amount of biomass — fronds, steps, and seaweed residues — produced by crops and seaweeds.

On average, ocean forests in temperate regions, such as Australia’s southern coast, produce between 2 and 11 times more biomass depending on area than intensively planted crops, productivity that can be harnessed for the food system.

Seaweed has been widely consumed in Asia for centuries, and is now in Western markets They pick upalbeit on a small scale, with more European and North American companies manufacturing Seaweed products for human consumption. The Cornish Seaweed Company has a wide variety of seaweed salad. Marks & Spencer offers a “coconut seaweed” snack, and there are several lines of kelp burgers.

“Although there is evidence that seaweed was consumed as food 14,500 years ago, it was not part of the diet of large segments of the world’s population,” says marine biologist Amanda Swinemer, who has been harvesting seaweed for decades through her company, Dakini Tide. and wild islands.

However, she adds, as food security becomes more of an issue, “people are looking for other sources of nutritious food. If seaweed is harvested properly, it has the potential to be a very sustainable, nutrient-dense food source.” Seaweed is also used as animal feed, in place of corn and soybeans, thanks to its high nutritional value.

Seaweed can be a nutritious source of food if harvested properly.
Seaweed can be a nutritious source of food if harvested properly. Photo: M&S

However, these underwater forests face multiple threats, including rising sea temperatures, pollution, and invasive species. Along the northern coast of California, kelp has decreased by more than 95% Over the past several years, sea urchins – whose populations have exploded with the advent of large numbers of sea stars, have decimated their main predators, Killed by wasting disease associated with a rise in water temperature.

Also seen are the Great Southern coral reefs along the Australian coast, and forests in the northwest Atlantic, along the coasts of Maine, Canada, and Greenland. Regarding tags from retreating.

Seagrass forests are often overlooked and less studied compared to coral reefs, which makes it difficult to understand how they are changing. “Most seagrass forests in the world have yet to be mapped, let alone monitored,” says Filbee-Dexter. While coral reefs are found in warm, calm, and easily accessible regions, making them fairly easy to study, kelp is found in colder waters on some of the most choppy and rugged coastlines in the world.

Filbee-Dexter believes that the more scientists understand these vital and fragile marine ecosystems, the easier it will be to help them survive. “I hope that more awareness about these forests will lead to more protection and restoration.”

In California, Hurd continues to dive among the kelp forests, watching their progress and hoping to halt their decline. “The loss of these incredibly productive ecosystems is devastating to both nature and people,” he says. However, as science continues to develop smarter kelp-tracking technologies, such as drones, satellites, and artificial intelligence, it remains hopeful that research will shed light on kelp’s role in combating climate collapse.

“One thing that should not be underestimated in particular is the productivity and biodiversity it supports around the world. It must be protected and restored with a great sense of urgency.”

Seagrass growth was measured by divers for the research.
Seagrass growth was measured by divers for the research. Photo: vernonwiley/Getty Images

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