The lava from the La Palma volcano raises the sea temperature to 51 degrees in La Fajana


These data have been obtained thanks to the deployment of several drones with thermal cameras from the ship piloted by the team SeaDrone of the Institute of Marine Sciences of Andalusia (ICMAN-CSIC). These high temperatures are registered especially at the front of the wash and just over 200 meters, according to the experts in marine sciences from the University of Las Palmas de Gran Canaria (ULPGC), Magdalena Santana and Melchor González, who took samples of casting in parallel on a Civil Protection vessel. In fact, the IEO team also took samples 500 meters from the fajana and the much smaller thermal anomaly, just 7 degrees. However, as Santana points out, these data have been able to change over the days since they are, like those relating to temperature, closely linked to wind and wave conditions.

Saltier than ever

The high temperatures that have been registered in the surroundings of the fajana are combined with an increase in salinity, which now resembles that area of ​​La Palma coast to the Hyper-salty lake of the Dead Sea (Jordan). With the 3,000 samples of seawater, obtained both from the Ramón Margalef ship and from drones a few meters from the wash, it has been determined that the salinity has become 41 parts per thousand, when it is normal for this index to be find in 36 or 37 part per thousand. “This is brutality,” says Eugenio Fraile, IEO oceanographer and head of the Vulcana project. The researcher recalls that in the Dead Sea the salinity reaches 42 parts per thousand. “The salinity increases due to the rapid evaporation of the water,” he explains.

The other substantial modification of the ecosystem is in the decrease in oxygen levels in the area, which, according to Fraile, “is directly related to the increase in temperature.” It is a chemical process by which the gases contained in the water escape due to the heat, leaving the ecosystem that becomes anaerobic. This lack of oxygen is reinforced by the scarce photosynthesis that marine organisms have been carrying out since the eruption erupted. And, as Fraile relates, volcanic ashes are accumulating in the upper layers of the sea, preventing the cytoplankton from capturing sunlight and, therefore, correctly performing its main function, which is to convert carbon dioxide into oxygen. .

Affects a few meters

These changes are especially affecting the surface layers of the ocean and the data collected at the moment shows a radius of action, it is for the moment, short. It is estimated that at the moment it affects between 5 and 15 meters deep and 200 meters from the front of the fajana. The consequences of these abrupt modifications of the ecosystem conditions are already showing some images of destruction and not only near the fajana.

More than 3,000 meters from the place where the lava has fallen like a great waterfall there is a marine reserve with a very high diversity of fauna and flora. Near the end of the reserve, in Puerto Naos, some species of ‘large’ fish have already been found dead on the coast. “Everything is related”, Fraile sentence, who emphasizes that “even if the changes are small, they will affect the ecosystem” because these organisms are very susceptible to them. In the long term, the consequences are still unknown. Everything will depend on how the volcanic crisis progresses in the coming days. “It is not something that we can already know,” explains Fraile, as there are many parameters that influence the viability of an ecosystem and the survival of the species that settle there.

Once they have returned to the port of Santa Cruz de Tenerife aboard the Ramón Margalef –after ten days of campaigning– the researchers will now go on to analyze the collected samples. The study will be completed in more detail in the laboratories of the IEO-CSIC’s Oceanographic Center of the Canary Islands, where turbidity, pH, existence of reduced species, carbon dioxide system, heavy metals, methane, nitrous oxide, as well as such as the abundance and diversity of the different compartments of marine plankton. These analyzes will allow the study of plankton microorganisms located at the base of the food chain, which respond quickly to disturbances. “We cannot analyze these parameters on board,” said the oceanographer, who highlights that, in addition, there are many of these data that still need to be corroborated in the laboratory. In this sense, Fraile emphasizes that it is necessary for researchers to invest as much time as possible in sampling the area affected by the volcano. “It is necessary to have the evolution of the parameters to know how the ecosystem can evolve, because it is a situation that is very difficult to repeat,” he insists.

Modifications in funds

On the other hand, the marine geology team has carried out a complete characterization of the seabed of the western area of ​​La Palma before and after the arrival of the lava. To do this, about 30 hectares have been mapped in different areas with a multibeam echo sounder and bottom samples have been obtained with rock dredgers. Scientists have been able to map the front of the lava delta underwater on a daily basis and obtain samples of corals in whose skeletons they will try to determine the presence of fixed magmatic helium during the eruption thanks to the collaboration of the University of Salamanca.

Although the Ramón Margalef will return to Vigo, at the IEO main station, to accommodate other oceanographic investigations that are being carried out in Spain, the ship Ángeles Alvariño is scheduled to arrive in the area on October 14. This first cousin of Ramón Margalef is the same meters in length and is only one year younger. This vessel has been used both for oceanographic campaigns carried out by the Canary Islands, as well as tasks such as searching for people in the depths of the sea. This ship is equipped with the ROV Liropus underwater vehicle that will allow direct observation of the lava entering the sea.

26

degrees

  • The rise in sea temperature in the area affected by the lava reaches 26 degrees Celsius. It is a thermal anomaly much greater than the one that caused the Tagoro.

41

parts per thousand

  • The evaporation of the water has caused the area to be much more salinized than usual, the figures are very similar to that of the Dead Sea where the salinity oscillates around 412 ppt.

2,800

meters

  • At 2,800 meters away from the fajana is Puerto Naos, where some fishermen warn of dead fish that researchers associate with the volcano.

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