A Multidisciplinary Approach to the Conservation and Monitoring of a Unique Cave Geosite: Portugal's World-Class Biodiversity Hotspot

Beneath the surface of the Earth lies some of the world's rarest, most endangered, and least protected species. Despite their critical importance, cave-dwelling animals are often neglected in major conservation policies. These species exhibit high levels of endemism and represent a unique natural heritage, while simultaneously providing vital ecosystem services, including roles in carbon and nutrient cycling. However, even in their isolated underground habitats, these organisms face significant threats from pollution and environmental changes.

In the karst region of the Algarve (Barrocal), a single cave has been identified as a global hotspot for subterranean biodiversity. Designated as a geosite by the aspiring UNESCO Global Geopark Algarvensis, this cave boasts an extraordinary concentration of endemic species, many of which are found nowhere else on Earth. As a unique natural site in Portugal, it is under acute threat from urbanization and surface area degradation, making its protection a critical priority.

This urgent situation has spurred the Barrocal-Cave project, a multidisciplinary initiative aimed at studying, protecting, and restoring this exceptional site. The project’s goal is to generate essential scientific knowledge to guide conservation efforts and establish a framework for its ecological assessment and long-term sustainability. Preliminary findings reveal that the cave atmosphere presents extreme stratification of oxygen (O₂) and carbon dioxide (CO₂) levels, with values potentially lethal at certain depths. Furthermore, the cave hosts a remarkably diverse community of more than 25 cave-adapted arthropod species, displaying notable seasonal variation.

As part of the ongoing work, the Barrocal-Cave project is pioneering the establishment of the first Long-Term Ecological Research (LTER) station in a cave environment in Western Europe while SAMEPA project is acessing past environmental changes through stalagmite studies. This effort provides the foundation for a formal conservation proposal, developed in collaboration with the Municipality of Loulé, to create a legal framework that ensures the protection and sustainable management of this exceptional cave ecosystem. By addressing the threats and challenges faced by this geosite, the project contributes vital insights to the broader field of subterranean biodiversity conservation.

 

This work is supported by Prémio Belmiro de Azevedo-FCT (2023.10009.PRIZE) and by Portuguese National Funds through “Fundação para a Ciência e a Tecnologia” (FCT) within SAMEPA Project PTDC/CTA-GEO/0125/2021 SAMEPA and  the cE3c and CIMA/ARNET Units’ fundings UIDB/00329/2020 (https://doi.org/10.54499/UIDB/00329/2020), UIDP/00350/2020 (https://doi.org/10.54499/UIDP/00350/2020 ) and LA/P/0069/2020 (https://doi.org/10.54499/LA/P/0069/2020).