Researchers from the University of Granada discover the presence of fresh water under the surface of the seabed of the Tropical Coast

The oceanographic campaign of the University of Granada Sanimed 24 concludes on the Granada coast after 20 days of observation and sample collection

Researchers from the University of Granada have concluded the Sanimed24 oceanographic campaign, carried out off the coast of Granada between the towns of Almuñécar and Calahonda between March 6 and 26, and have discovered the presence of fresh water just a few meters below the surface of the seabed. This was reported by the UGR through a press release.

The working group that carried out the research, led by researchers Ángel Puga Bernabéu, from the Department of Stratigraphy and Paleontology of the University of Granada, and Francisco J. Lobo, from the Andalusian Institute of Earth Sciences, has concluded with two discoveries of great impact. Firstly, the presence of fresh water just a few meters below the surface of the seabed in the places that had been hypothesized in the project. It is the first time, the researchers explain, that evidence of an underwater aquifer has been found on a platform on the Iberian margin.

The second great result has been the identification of a bioconstructed habitat for oysters of the genus Neopycnodont at 500 meters deep in the Carchuna canyon. These oysters are common in shallow waters – less than 100 meters deep – on the platforms of the Mediterranean coast but not at five times that depth.

Furthermore, black corals grow on these oyster reefs under special protection, a priori Antipathes cf. dichotoma and Parantipathes cf. larix, as well as the protected scleractinium Lophelia pertusa. Knowledge of this type of habitat is scarce worldwide, as there are very few known examples of oyster reefs at these depths. The known examples are also associated with submarine canyon environments, but there are no examples similar to those that have been described in the Carchuna Canyon.

Sanimed24 oceanographic project

The Sanimed project has among its objectives to decipher the genetic mechanisms and importance of gravitational flows in deltaic and underwater canyon environments, determine the influence of anthropogenic activity in relation to the distribution of garbage on the seabed and its impact on benthic ecosystems, the distribution of garbage in the water column and the effect of the damming of the Guadalfeo River on coastal sedimentary dynamics and corroborate the presence of underwater discharges and storage of fresh water in the underwater environment of the Guadalfeo River delta and the head of the canyons submarines.

In addition to the main discoveries, more than 300 meters of sediment cores with individual lengths of up to 8.5 meters were collected during the campaign, which, together with the high-resolution acoustic profiles acquired, will allow the reconstruction of the sedimentary conditions and paleoecologies of the study area during the rise in sea level linked to the last deglaciation.

The data obtained with autonomous and remotely operated submersible vehicles have allowed the obtaining of very high resolution bathymetries (less than one meter) in areas where there is active sediment transport and the obtaining of high resolution videos and images that show the existing benthic communities in underwater canyon environments (some of them of special ecological interest) and the accumulation of garbage in specific areas of the Carchuna and Motril canyons.

Finally, the collection of microplastics in the water column at different depths and distances off the coast will provide very relevant information about the dynamics of these particles on the Granada coast, their permanence in the water column and their potential transfer to the accumulated sediment on the seabed.

This year’s campaign has had the multidisciplinary participation of scientists from the University of Granada (departments of Stratigraphy and Paleontology and Geodynamics), the Andalusian Institute of Earth Sciences-CSIC, the Oceanographic Institute of Spain, the universities of Almería, Cádiz, Las Palmas, Algarve (Portugal) and Ghent (Belgium), the Institute of Marine Sciences (Barcelona) and the Ceuta Sea Museum Foundation. “The training participation of five students of the Degree in Geology and two postgraduate students from the University of Granada who were able to obtain relevant data for the completion of their doctoral theses has been interesting,” adds the University of Granada in its communication of the results of the investigation.