The climate crisis's hidden underwater woods might be addressed

 

Mon 2 Jan 2023 06.00 GMT

Although kelp has a high nutritional value and can absorb carbon dioxide, it is threatened by pollution, rising temperatures, and invasive species.

Frank Hurd slowly separates the big kelp's curtains while bubbles shoot out in front of him rapidly. Through the chilly waves of the Pacific Ocean, streamers of green and gold rise up towards the sun.

Hurd, a marine scientist with the Nature Conservancy, is diving in a kelp forest off Anacapa Island, one of the protected rocky volcanic islets that make up the Channel Islands national park, an archipelago off the coast of southern California.

This seaweed, which is dense and vigorous, is a minor component of the underwater forests that cover practically every continent's shoreline. Some of them have received a fair amount of research, such as the Great African Sea Forest, which stretches north from Cape Town to the Namibian coastline and served as the backdrop for the movie My Octopus Teacher, and the Great Southern Reef, which is a massive kelp forest that hugs Australia's southern coastline. However, many more of these woods are undescribed and unknown—they are submerged.

Off Santa Barbara, California, among the lush underwater woods, a harbour seal emerges from the kelp canopy.

Due to the challenges of monitoring ocean depths with satellites, kelp has historically been challenging to map even though it is one of the fastest growing plants on Earth. However, research that was released in September discovered that seaweed forests are far larger than previously thought.

In order to model the global distribution of ocean forests, an international team of scientists from eight nations, under the direction of Dr. Albert Pessarrodona from the University of Western Australia, manually combed through hundreds of studies, including local plant data records, online repositories, and citizen science initiatives. They discovered that underwater forests occupy between 6 and 7.2 million square kilometres, an area that is twice the size of India and equivalent to the Amazon rainforest basin.

A shot from the film My Octopus Teacher is located in a lush area of enormous bamboo kelp that stretches from Cape Town to the Namibian coast.

By collecting carbon dioxide from the atmosphere and seas, seaweed forests can operate as a crucial barrier against the climate problem. One study suggests that ocean forests may store as much carbon as the Amazon rainforest.

However, because seaweed lacks a root system to lock the carbon into the earth, in contrast to other marine plants like mangroves and seagrass, there is still a substantial knowledge gap about its long-term capacity to sequester carbon. What happens to the seaweed also affects whether the carbon is kept locked up, and the effectiveness of seaweed as a carbon sink is still a matter of scientific controversy.

Fish, marine creatures, and birds can find food and refuge in kelp.

As one of the study's 10 authors and a marine ecologist, Dr. Karen Filbee-Dexter said, "because it calculates the productivity - growth and carbon uptake - of the largest marine vegetated ecosystem," the research represents a "major step forward" in our understanding of the potential role that seaweed may play in preventing climate breakdown. She continued by saying that it may also be used to calculate the maritime forests' potential as carbon sinks.

The biggest kind of seaweed, kelp, which can reach heights of tens of metres, is particularly essential to marine ecosystems because it gives fish, other marine creatures, and birds food and a place to live.

The weedy seadragon, a purple-hued organism with appendages that resemble kelp fronds that exclusively lives in Australia's coastal waters, calls native kelp its home. Southern sea otters need kelp forests along the Pacific coast of North America as their primary home. In addition, throughout its voyage from Baja California in Mexico to Alaskan seas, the great grey whale uses kelp forests as a refuge from rapacious killer whales and as an essential feeding area for its young.

In Jervis Bay, New South Wales, Australia, a weedy sea dragon

Due to their fast development, underwater forests may potentially contribute to attempts to address the global food security challenge.

The researchers looked at hundreds of distinct studies from all across the world where scuba divers had monitored the development of seaweed. According to the study, "we found that ocean forests are more productive than several intensively farmed crops, such as wheat, rice, and maize." The amount of biomass, or the fronds, stipes, and holdfasts of seaweed, generated by crops and seaweed, was used to determine productivity.

Ocean forests generated between two and eleven times more biomass by area than intensively cultivated crops on average in temperate places, such as Australia's southern coast. This productivity might be used to benefit the food chain.

Seaweeds have the potential to be a very        sustainable and nutrient-dense food source if they are collected appropriately                        

Since Asia has long been a major consumer of seaweed, western markets are also catching on, albeit slowly, with more European and North American businesses producing seaweed products for consumption. Seaweed salads from The Cornish Seaweed Company, "coconut seaweed crunch" snacks from Marks & Spencer, and many kelp burger varieties are also available.

According to marine researcher Amanda Swinimer, whose business, Dakini Tidal Wilds, has been wild collecting seaweed for decades, "Although there is evidence that seaweed was ingested as food 14,500 years ago, it has not been a component of the diet for significant swathes of the world's population."

However, she continues, "people are seeking for new sources of healthy food as food security becomes more of a problem. Seaweeds have the potential to be a very sustainable and nutrient-dense food source if they are collected appropriately. Due to its excellent nutritional content, seaweed is frequently substituted for corn and soy beans in animal feed.

If gathered properly, seaweed may be a healthy source of food.

However, there are several challenges to these underwater forests, including invasive species, pollution, and warming sea temperatures. Kelp has decreased by more than 95% throughout the northern California coast in recent years due to sea urchin devastation, whose population has grown while starfish, their primary predators, have been ravaged by a wasting illness linked to warmer waters.

Forests in the north-west Atlantic, along the shores of Maine, Canada, and Greenland, as well as the Great Southern Reef along Australia's coastline, are all exhibiting alarming symptoms of loss.

Compared to coral reefs, seaweed forests are frequently ignored and understudied, making it challenging to comprehend how they are evolving. According to Filbee-Dexter, "the majority of the world's seaweed forests are not even documented, much less monitored." While kelp is located in frigid seas on some of the world's most turbulent, rugged coastlines, corals are found in warm, calm, and accessible locations, making it relatively straightforward to study them.

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The more that scientists know about these important but vulnerable marine ecosystems, in Filbee-opinion, Dexter's the simpler it will be to support their survival. "I'm hoping that raising awareness about these woods will result in more of them being protected and restored."

Hurd continues to dive in the kelp forests of California, keeping track on their development and seeking to slow down their demise. He claims that the loss of these extraordinarily productive ecosystems would be disastrous for both environment and mankind. He is still optimistic that study will be able to shed light on the function of kelp in preventing climate breakdown, though, as science continues to create better technology to track kelp, such as drones, satellites, and AI.

The productivity and biodiversity that kelp, in particular, provides globally are two things that should never be taken for granted. With extreme urgency, it has to be preserved and repaired.

Scuba divers assessed seaweed growth for the study.