Benthic macroinvertebrates in a tufa-depositing environment: a case study of highly vulnerable karst lotic habitats in Southeast Europe

Karst freshwater ecosystems are considered biodiversity hotspots, highlighting their sensitivity and vulnerability to environmental change. However, our understanding of the distribution and ecology of macroinvertebrates in lotic karst habitats is still incomplete. Therefore, to fill the knowledge gaps, the current study was conducted in the Dinaric and Carpathian–Balkan Mountains in Serbia, Southeastern Europe. We studied aquatic macroinvertebrates and their relationship with environmental parameters at 25 sampling sites in three habitat types (springs, the upper reaches, and tufa barriers) in 12 rivers and streams in Serbia, seasonally, between 2019 and 2022. We recorded 85,072 individuals within 206 taxa. Most environmental variables were comparable among the three habitat types, which most probably resulted in comparable abundance and diversity of benthic macroinvertebrates. However, taxa richness was lower in springs compared to upper reaches and tufa barriers. Environmental parameters had a greater impact than spatial effects on shaping the macroinvertebrate community. Moreover, IndVal analysis revealed a list of 30 indicator taxa associated with specific habitat types. We emphasized that highly specialized species support vulnerable functions in high-diversity karst freshwater ecosystems. Therefore, this study establishes a scientific foundation for implementing effective management strategies for these unique aquatic ecosystems.