The study, recently published in the world's leading scientific journal ‘Nature Communications’, highlights the potential of these marine habitats to capture the planet's excess carbon
International research, in which the ECOAQUA Institute of the University of Las Palmas de Gran Canaria (ULPGC) has participated, has revealed the crucial role played by coralline algae banks in the ocean carbon cycle.
Known in the Canary Islands as’ confites’ because of the white colour they acquire when they finish their life span and are washed ashore, this study provides new evidence of the capacity of these habitats to fight climate change by being a very effective tool to combat the excess carbon in the planet, the result of burning fossil fuels.
The results, recently published in ‘Nature Communications’, an international reference journal on scientific breakthroughs, show that these marine habitats, distributed around the world and built by rhodoliths, with a striking underwater pink colour, are able to absorb large amounts of atmospheric carbon and accumulate calcium carbonate, which makes them an important carbon sink key to the future of the planet.
The publication reveals that underwater coralline algae beds, which cover large areas of the planet's coastal shelf and which in Las Palmas de Gran Canaria give rise to place names such as El Confital, can absorb up to 1,347 grams of carbon per square metre per day, surpassing other marine ecosystems formed by macroalgae such as laminaria or brown algae. These habitats are mostly reddish-pink in colour, a typical shade of rhodoliths, which gives them a very particular chromatic identity.
The research, entitled ‘Pink Power: The Importance of Coralline Red Algal Banks in the Ocean Carbon Cycle’, was conducted by an international team of scientists from different universities and centres led by Dr. Nadine Schubert, from the University of Algarve (Portugal), with the participation of researchers Fernando Tuya, Francisco Otero-Ferrer and Fernando Espino from the Biodiversity and Conservation Group (BIOCON) of the ECOAQUA Institute, on behalf of the University of Las Palmas de Gran Canaria.
The results of the study, which covered a wide geographical range, including both subtropical and temperate Atlantic waters, underline that these ecosystems not only contribute to the carbon cycle through photosynthesis, but also accumulate large amounts of calcium carbonate in their structures, making them long-term stable carbon reservoirs.
Until now there has been little information on their productivity, as the dynamics of net carbon flux and carbonate pools make it difficult to assess their contribution to the global ocean carbon cycle.
The data, which cover wide bathymetric ranges from 2 to 51 metres, show that ‘coralline algal beds are highly productive habitats, with substantial carbon uptake rates of between 28 and 1,347 grams per square metre per day,’ says researcher and co-author Fernando Tuya.
These rates, which vary depending on light availability and species composition, exceed estimates reported for other macroalgal habitats, which are more documented to be important in the global carbon cycle.
Implications for global conservation
‘This high productivity, together with their considerable carbonate deposits (0.4-38 kilotonnes), makes coralline algal beds highly relevant contributors to the current and future ocean carbon cycle, playing a very important role as a sink for excess carbon,’ says Tuya, head of ECOAQUA's BIOCON group.
These characteristics give them a fundamental role in the fight against climate change, so their protection is vital for the conservation of the marine environment around the world.
Tuya highlights the ‘imperative need’ to incorporate rhodolith banks in marine conservation programmes, as ‘they are highly productive marine ecosystems and of great relevance for the absorption of carbon at a global level’.
In the words of the researcher, ‘these results provide solid arguments for their inclusion in relevant national or international conservation frameworks, such as the Natura 2000 network, where these habitats are not currently included’.
This finding is particularly relevant in acontext of increasing ocean acidification, as although this phenomenon may accelerate the dissolution of carbonate deposits, it may also enhance the ability of coralline algal beds to sequester carbon dioxide.
In addition to ECOAQUA's BIOCON group, which had already carried out similar initiatives to those of this study, albeit in purely local areas such as MAC-RODO, this research has involved the participation of a total of 17 universities and scientific institutions from Spain, including the Atlantic Biodiversity and Sustainability Association (ABAS) in Telde (Gran Canaria), Portugal, Italy, France, Ireland, Brazil and Australia.