Wednesday, October 20

The ocean of the future is studied on La Palma thanks to volcanoes

The ocean of the future is being studied on La Palma, about 20 kilometers south of the enclave where this Tuesday night the sea and the lava that gushed from the new volcano merged. The coast of Fuencaliente, at the southern end of the island, has unique conditions in the world that make it a natural laboratory for the study of one of the effects of climate change: ocean acidification that threatens the integrity of marine ecosystems .

The lava from the La Palma volcano creates a huge delta 500 meters wide and discolors the sea

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Scientists from the two public Canarian universities have been investigating for years in this coastal strip the outcrops of carbon dioxide on the coast and how they affect the chemistry of sea water and biodiversity, the organisms that inhabit it. They are emissions of volcanic origin, originating from the degassing of magma, which alter the underground waters that descend from the center of the island and are discharged to the coast. During low tides, the PH of the water is reduced to a point in this area, it becomes much more acidic. This behavior serves to predict the consequences in the oceans of the increase in CO2 emissions on the planet due to human activity, the main cause of global warming.

The road that leads to this place, in the southern corner of La Palma, stops before the two lighthouses of Fuencaliente. The old one, built with basalt stone from Arucas (municipality of Gran Canaria), was damaged by the eruption of the Teneguía volcano in 1971 and by the previous seismic swarm and rehabilitated at the beginning of the century after three decades of neglect. The new one, red and white, was built in the mid-eighties to replace it, just 30 meters away. To the east are the Fuencaliente salt flats, a point of scientific interest as it is a resting place for migratory birds. To the west, less than a kilometer away, is the beach that was born from the material ejected during the Teneguía eruption, called Echentive or Playa Nueva.

At the base of the old Fuencaliente lighthouse, a space has been set up to house the Marine Observatory on Climate Change. José Carlos Hernández, professor of Marine Biology at the University of La Laguna (ULL), is its director. “La Palma is one of the three places in the world where water becomes naturally acidic. The other two are Ischia (the largest island of the Campania or Neapolitan archipelago, in Italy) and Papua New Guinea (the second largest island in the world , located in the north of Australia). They are exceptional sites. It is important because, through them, we can foresee what the oceans of the future will be like. Furthermore, on La Palma there is no bubbling and in the other two places there is, so it is you can study without that mechanical impact on the organisms that are going to settle on this site, “he explains.

The find came by chance. It was a doctoral student, Celso Hernández, who noticed the peculiarity when he worked with the professor of Biology at the ULL in a project of the Ministry of Science and Environment. When taking samples to measure how the algae absorb carbon dioxide and emit oxygen, he noticed that in one of the checkpoints on the coast the PH was extremely acidic compared to the usual values. After a period of mistrust and after numerous analyzes with the same results, the light bulb was turned on. “Already in 2015 we realized what was happening there.” Hernández contacted Melchor González and Magdalena Santana, professors of Marine Chemistry at the University of Las Palmas de Gran Canaria (ULPGC), to incorporate them into the working group and, from there, they found other locations where the same phenomenon occurred.

“When we arrived, we analyzed samples and saw that, during low tide, the PH of the water had values ​​of 7.1 or 7.2. It’s outrageous. The normal PH is 8, 8.05 …”, Melchor González relates, who specifies that since the Industrial Revolution, this indicator of the acidity of the oceans has dropped one tenth across the planet and that the models foresee a decrease of three or four tenths between now and the end of the century. Why is it decreasing so much in that area of ​​Fuencaliente? “The water that descends from the aquifers, from the central area of ​​La Palma, passes below the Teneguía, feeds back from the seabed itself in those rocks, which are porous, and when it comes out, at low tide, there is a release of pressure that lets out carbon dioxide. That is why it gives highly acidified values ​​”, points out the expert in Oceanography.

Magdalena Santana clarifies that these carbon dioxide emissions are very slight, but significant enough for the investigation. They have nothing to do with those that occur during eruptive processes such as the one that is occurring at the moment on the west slope of La Palma, in the volcanic building of Cumbre Vieja, or the one that occurred a decade ago in the sea of ​​Las Calmas, in the south of the island of El Hierro, where the ecosystem was completely destroyed to regenerate months later and regain its wealth. “The immediate emissions are very drastic. In El Hierro, the PH dropped three points. This only occurs when a volcano erupts in the sea. Here we are talking about a remnant of emissions from areas where there have been historical eruptions. They are variations very, very small, but they are important for the study because they allow us to model behaviors “, he remarks.

This Marine Chemistry working group has been studying the levels of carbon dioxide and acidification in the open ocean for 25 years. In the north of the islands there is one of the three stations that provides time series data to the Intergovernmental Panel on Climate Change (IPCC). The other two are in Hawaii and Bermuda. “A few years ago, we wanted to see if the same trends that we were observing in the open ocean, due to the action of man, were obtained on the coasts. Since 2020 we are conducting studies in the Canarian region,” asserts Santana. Although it is not possible to talk about trends yet, because the study period is still short, the first data do point to a similar behavior in the coastal strip, an increase in the absorption of carbon dioxide. For this reason, the phenomenon that occurs in the south of La Palma, in the municipality of Fuencaliente, is relevant to analyze how the oceans of the future are going to function.

“Winners and losers” in the ecosystem

During these years of research, the ULL professor José Carlos Hernández has already been able to verify the first consequences of this acidification of the water on marine biodiversity, its structure and composition. “It is a completely different ecosystem from the one we have now. We are studying adaptation phenomena. Will all organisms become extinct or will there be some that will be able to resist in the oceans of the future, with more CO2, more acids? Some species will adapt and others will disappear completely. There will be winners and losers “in this process, explains the marine biologist.

Those that lose the most are calcareous organisms. “That means that calcifying organisms, which are many of them, are going to have a much more difficult time,” he says. For example, the burgados. “We are seeing how the shells of these marine snails are dissolving. And that is going to have a series of repercussions on the population. For example, that their shells are much more fragile and that there is greater predation on these individuals or that they endure less the environmental conditions since that portable house that they have is being destroyed “. It is also expected that large underwater forests will disappear under these conditions, such as the bottoms of gongolaria abies-marina, “which is the yellow moss”, or “the black moss” that can be found in the area of ​​Puerto de la Cruz (Tenerife). or La Gomera. “Those large forests will disappear. To make a terrestrial simile, it is as if the redwood forests disappear and only savanna areas remain.”

The ‘winners’ will be the species “that grow very fast, that are small in size and that can resist the acid effect of the carbon dioxide emanation.” “Macroscopic organisms, the ones we all know, invertebrates, some large fish, are not common in acidic places. Small organisms are: marine worms, small crustaceans … Another type of community. And this has a series of implications in the rest of the trophic chain that we are currently investigating “, indicates Hernández, who speaks of much more diverse communities of microscopic,” miniaturized “organisms.

The next step in the study is to check how this change produced by ocean acidification will affect the organisms above it, the fishery resources. “In the case of the burgado, it has a negative effect. But we also want to see if that structure in the bento community (organisms that inhabit the bottom of marine ecosystems), which is associated with the rock, that lives attached to the rock, it will modify, for example, the production of oxygen, the habitat that fish have to live in these places and so on until they reach us. That is, what consequences this phenomenon will have on the biomass of fish products “.

“The island of La Palma is unique in many respects, but this is one of the most remarkable from the marine point of view. We have been very interested in it since we found this point by pure chance. There are very few in the world and for That is why we decided to work together to create this Marine Observatory on Climate Change “, affirms the professor from the ULL, who appreciates the involvement in the project of both the two Canarian universities and the Fuencaliente City Council.

Melchor González highlights the importance of this natural phenomenon. “In Gran Canaria we are doing a study of mesocosms. We take bags of water between 8 and 20 cubic meters and we put different concentrations of dissolved carbon dioxide. On La Palma, instead of having these watertight conditions, you have an ocean that renews the water, that depending on whether you go to the coast or the open sea changes the PH, with which simply by putting some organisms closer or further from the coast, you are simulating conditions that occur naturally in an open ocean and that is very interesting for research, “he concludes.

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