# Subterranean Biodiversity on the Brink: Urgent Framework for Conserving the Densest Cave Region in South America

## TL;DR

A study in southeastern Brazil highlights the urgent need to protect the region's highly diverse and threatened cave ecosystems.

## Contribution

The paper introduces a novel framework for identifying high-priority caves for conservation based on biodiversity and human impact data.

## Key findings

- 32 cave-restricted species were identified, with half found in just seven caves.
- Agriculture and mining are the main threats to subterranean biodiversity in the region.
- Seven caves contain 50% of the region’s cave-restricted species.

## Abstract

Subterranean ecosystems in southeastern Brazil are both fragile and highly biodiverse, yet they face severe threats from agriculture, mining, and urban expansion. In our survey of 105 caves, we identified 32 cave-restricted species, half of them concentrated in only seven caves. These subterranean habitats represent sites of global importance and require urgent, targeted conservation measures to prevent the irreversible loss of biodiversity.

Subterranean ecosystems represent some of the most unique and fragile habitats on Earth, yet they remain poorly understood and highly vulnerable to human-induced disturbances. Despite their ecological significance, these systems are rarely integrated into conservation planning, and surface-level protected areas alone are insufficient to safeguard their biodiversity. In southeastern Brazil, a karst landscape spanning approximately 1200 km2, recognized as the region with the highest cave density in South America (approximately 2600 caves), is under increasing pressure from urban expansion, agriculture, and mining, all of which threaten the ecological integrity of subterranean habitats. This study sought to identify caves of high conservation priority by integrating species richness of non-troglobitic invertebrates, occurrence of troglobitic species, presence of endemic troglobitic taxa, and the degree of anthropogenic impacts, using spatial algebra and polygon-based mapping approaches. Agriculture and exotic forestry plantations (54%) and mining operations (15%) were identified as the most prevalent disturbances. A total of 32 troglobitic species were recorded, occurring in 63% of the 105 surveyed caves. Notably, seven caves alone harbor 25% of the region’s known cave invertebrate diversity and encompass 50% of its cave-restricted species. The findings highlight the global significance of this spot of subterranean biodiversity and reinforce the urgent need for targeted conservation measures. Without immediate action to mitigate unsustainable land use and resource exploitation, the persistence of these highly specialized communities is at imminent risk.