Eight new deep-sea species of marine sponges discovered

Despite marine sponges being widespread on our planet, their biodiversity and distribution is still poorly known. Even though the Mediterranean Sea is the most explored sea on Earth, a study by Díaz et al. (2024) reveals the presence of new sponge species and new records in unexplored habitats such as underwater caves or mountains around the Balearic Islands.

The new discoveries will increase the ecological importance of the Mallorca channel seamounts and the littoral caves, providing compelling arguments for the Spanish government to emphasize the need for protection measures. Regarding the underwater mountains, the data suggests a strong case for their inclusion within the Natura 2000 Network, highlighting their ecological significance and the necessity of conservation efforts.

Sponges are aquatic animals that live attached to the bottom of the sea and feed on bacteria and other microscopic food by constantly filtering large amounts of seawater. We currently know more than 9,600 species worldwide, with still many parts of the world unexplored. The sponge fauna of the Western Mediterranean is one of the most studied in the world and yet, the sampling of new habitats in this region is usually an opportunity to reveal new species. Julio A. Díaz, a PhD student of the Balearic Oceanographic Centre of the Spanish Institute of Oceanography (CSIC), together with other researchers from the same centre, have been collecting sponges in the Balearic Islands, Spain. Collections came from shallow underwater caves to deep-sea fishing grounds and underwater mountains (seamounts), descending to depths of up to 1000 meters. With Docent Paco Cárdenas, sponge taxonomist and zoology curator at the Museum of Evolution, Uppsala University, they have focused on one particular large group of sponges, the tetractinellids, for which substantial comparative material is available in the collections of the Museum of Evolution.

Before this study, only 16 of the 83 Mediterranean tetractinellid sponges had been recorded in the Balearic Island region. This study identified a total of 36 tetractinellid species, and discovered in the process eight new species for science, such as Stelletta mortarium, which was named after the typical kitchen mortar commonly used in Mediterranean cuisine, because of its cup-shape; or Geodia matrix named after its tendency to accumulate all kind of different elements in its body. Two new species honour two important sponge scientists: Dr. Maria Antònia Bibiloni, who was key to initiate sponge research in the Balearic Islands in the 1980s, and Dr. Joana R. Xavier for her continuous efforts and leadership to support deep-sea sponge research. In addition, some species were re-discovered since their description 40 years ago.

Julio A. Díaz is supported by the Regional Government of the Balearic Islands and the European Social Fund. This study has been carried out in the scope of the LIFE IP INTEMARES project, which aims to improve the scientific knowledge of the Mallorca Channel seamounts for its inclusion in the Natura 2000 Network and the MEDITS research surveys, co-funded by the European Maritime and Fisheries Fund and the Spanish National Program of collection, management and use of data in the fisheries sector and support for scientific advice regarding the Common Fisheries Policy. Additional support has also been available from the SosMed project, funded by Next Generation European funds (Recovery, Transformation and Resilience Plan). Furthermore, the specimens collected by J. A. Díaz within the LIFE IP INTEMARES project will support P. Cárdenas’ current research project SponBIODIV (co-funded by the EU and FORMAS), which is aiming to establish a sponge biodiversity baseline knowledge in the Atlanto-Mediterranean region.