In 2014 the researcher of the University of Vigo Anxo Mena published a doctoral thesis in which he showed that the massive shedding of icebergs in the North Atlantic, known as the Heinrich Events, caused the greatest climate change in Galicia’s oceanography. That study was focused, above all, on how these changes affected microorganisms such as plankton. However, in those moments, little or nothing was known about the transformations that had occurred in the macro benthic community, in the set of animals that inhabited at that time the bottom of the so-called Galicia Interior Basin, an underwater depression of more than 3000 meters deep that stretches from north to south about a hundred kilometers from the Galician coast. These data now come from the hand of an international team that includes Anxol Mena and the professor who directed his thesis, Guillermo Francés, both researchers of the Geological Oceanography and Biogeochemistry research group at the CIM-UVigo Marine Research Centre; the professor Francisco Javier Tovar, of the University of Granada, who led the study, and the researcher from the Royal Holloway University of London Javier Dorador.
The study was published this week in the Global and Planetary Change journal and it is a continuation of the multidisciplinary study that is being carried out on the Galicia Interior Basin, a line of research that started with Mena’s own doctoral thesis, research which was now used as a theoretical framework for this new phase of the study, especially in what refers to the chronological information and the existing sedimentary processes.
Changes that occurred in the Pleistocene serve as a model for the future
This new article delves into how the Heinrich Events, which are those abrupt climatic changes that occurred in the Pleistocene, brought large amounts of icebergs to the latitudes of Galicia, changed the macrobenthic communities and, therefore, the traces they left on the sediment. “Knowing how abrupt climatic changes affect the benthic habitat is very important because it helps us to understand the action of the water masses, not only in relation to sedimentary processes, but also in relation to associated benthic fauna “, Mena explains. He stresses the fact that being able to know this, both the global scale and the regional scale, “allow us to see the variations within the same system to the same alterations”, an issue that is not minor if we take into account a current climate change situation. “Knowing what happened in the past is the best way for the scientific community to get an idea of how Galicia’s oceanography and climate would react to a similar event, characterized, above all, by the release of fresh water to the ocean ” Mena emphasizes.
Coinciding with the arrival of fresh water on the ocean surface, the benthic fauna was seriously reduced
For the launch of the study, they focused on the so-called Heinrich Event 1, which is the closest to today, and which is located approximately 16,000 years ago. After analyzing all the data, the results indicate that these macrobenthic communications were changing at the time of the climatic event and also according to their relative position towards the coast. “In this way, during the most extreme part of the Heinrich Event, when the largest number of icebergs arrived, these communities were greatly reduced or almost disappeared due to the lack of oxygen conditions of the sedimentary surface, recovering this community once this event is mitigated or it is no longer so extreme”, the UVigo researcher stresses.
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 Galicia Interior Basin and to the oceanography and the action of the water bodies on the slope and the bottom of the basin”, the researcher explains.
The Geological Oceanography and Biogeochemistry group´s research activities are cofunded by the European Union through the ERDF Operational Program Galicia 2014-2020.
Source: DUVI
