Congeria in the Dinaric Karst: conservation and scientific study of a unique cave-dwelling bivalve genus

Congeria, one of the few extant genera of cave-dwelling bivalve mollusks, is endemic to the Dinaric Karst and currently comprises three distinct species with highly fragmented distributions, facing serious threats of extinction. Here we highlight the unique life history traits exhibited by Congeria and discuss the potential of ongoing and future scientific research in addressing the critical challenges associated with its conservation. The subterranean waters of the Karst represent a highly stable yet vulnerable ecosystem that has been significantly impacted by human activities over the past few decades. Hydrotechnical projects have notably reduced water flow to underground habitats that are essential for the reproduction and survival of Congeria, leading to habitat loss and severe population declines in several areas. These challenges, together with water pollution, intensive agriculture and tourism, are projected to cause further population decreases in the coming decades, exacerbated by inadequate regulatory measures and our limited understanding of the biology of these bivalves. Scientific advancements, which include the recently completed sequencing of the genome of C. kusceri, have the potential to provide critical insights into previously unexplored aspects of Congeria biology, unveiling the molecular mechanisms underlying its adaptive success in this challenging environment. Such research may offer a platform for an improved understanding of the factors underpinning the adaptation of Congeria to the subterranean environments and a comprehensive assessment of the genetic health, demographic history and resilience of the three extant species in the face of habitat alterations.