In 2014, the researcher from the University of Vigo Anxo Mena published a doctoral thesis in which he demonstrated that the massive iceberg calvings in the North Atlantic, known as Heinrich Events, caused the greatest climate change in the oceanography of Galicia. That study focused, above all, on how these changes affected microorganisms such as plankton, but at that time little or nothing was known about the transformations that had occurred in the macrobenthic community, in the set of animals that inhabited at that time the bottom of the so-called Interior Basin of Galicia, a submarine depression of more than 3000 meters deep that extends from north to south about one hundred kilometers from the Galician coast. These data now come from the hand of an international team that includes Anxo Mena himself and the professor who directed his thesis, Guillermo Francés, both researchers from the Geological Oceanography and Biogeochemistry research group of the CIM-UVigo Marine Research Center; Professor Francisco Javier Tovar of the University of Granada, who led the study, and Royal Holloway University of London researcher Javier Dorador.
The work was published this week in the journal Global and Planetary Change and represents a continuation of the multidisciplinary study being carried out on the Interior Basin of Galicia, a line of research that began with Mena’s own doctoral thesis, research that has now been used as a theoretical framework for this new phase of the study, especially with regard to chronological information and existing sedimentary processes.
Changes that occurred in the Pleistocene and that serve as a model for the future
This new article delves into how the Heinrich Events, which are those abrupt climate changes that occurred in the Pleistocene and brought large quantities of icebergs to the latitudes of Galicia, changed the macrobenthic communities and, therefore, the footprints that these left on the sediment. “Knowing how abrupt climate changes affect the benthic habitat is very important because it helps us understand the action of water masses, not only in relation to sedimentary processes, but also in relation to the associated benthic fauna”, explains Mena, who emphasizes the fact that being able to know this, both on a global scale and a regional scale, “allows us to see the variations within the same system to the same alterations”, a question that is no less important if we take into account the current climate change situation. “Knowing what happened in the past is the best way for the scientific community to get an idea of how the oceanography and climate of Galicia would react to a similar event, characterized, above all, by the release of freshwater into the ocean”, emphasizes Mena.
Coinciding with the arrival of freshwater at the ocean surface, benthic fauna was seriously reduced.
To launch the study, they focused on the so-called Heinrich Event 1, which is the closest to the present day, and which is located approximately 16,000 years ago. Once all the data were analyzed, the results indicate that these macrobenthic communities were changing at the time of the climatic event itself and also according to their relative position towards the coast. “Thus, during the most extreme part of the Heinrich Event, when the largest number of icebergs arrived, these communities were very reduced or almost disappeared due to the oxygen-deficient conditions of the sedimentary surface, this community recovering once this event is mitigated or ceases to be so extreme”, emphasizes the UVigo researcher.
On the other hand, the study also found that these macrobenthic communities also change according to their proximity to the coast. “The areas closest to the coast have greater diversity and abundance of animals than the more distant areas, due both to the topography of the Interior Basin of Galicia itself and to the oceanography and the action of the water masses on the seabed and the bottom of the basin,” explains the researcher.
The research activity of the Geological Oceanography and Biogeochemistry group is co-financed by the FEDER/FSE Galicia 2014-2020 Operational Program.
Source: DUVI
