Giant Kelp 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 hugging the southern coast of Australia, but many of these forests are little-known and unknown – hidden underwater.
Despite being one of the fastest growing plants on Earth, kelp has historically been difficult to map due to the difficulties of satellite ocean bathymetry. Research published in September found that seagrass forests are much more extensive than previously realized.
Underwater forests cover between 6 and 7.2 million square kilometres
An international group of scientists from eight countries, led by Dr. Albert Pessarrodonna of the University of Western Australia, manually sifted through hundreds of studies — including local plant data records, online repositories and citizen science initiatives — to model the global distribution of ocean forests, and found that underwater forests cover Between 6 and 7.2 million square kilometers – an area comparable to the Amazon rainforest basin and twice the size of India.
A vital buffer against the climate crisis
Seagrass forests could act as a vital buffer against the climate crisis, absorbing carbon dioxide from seawater and the atmosphere. According to one analysis, ocean forests may store as much carbon as the Amazon rainforest.
And there is still a huge gap in understanding the long-term ability of seagrasses to sequester carbon, because they lack a root system to sequester carbon in the ground, unlike other marine plants such as mangroves and seagrasses. Whether carbon remains locked up also depends on what happens to the seagrass. There is still scientific debate about how effective it is in storing the element.
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,” she added, adding that it could also help estimate the carbon sequestration potential of the world’s marine forests.