Work

Challenges of the assessment of nature conservation value of aquatic habitats using microalgae

Year: 2026

Type: article

Abstract: The increasing focus on ecosystem restoration in European environmental policy highlights the need for reliable methods to quantify the nature conservation value (NCV) of aquatic habitats. Current Water Framework Directive (WFD) metrics assess ecological quality mainly through the phytoplankton community composition and abundance. However, these approaches do not reflect properly the real conservation value of the habitats, because they overlook the contribution of rare and unique algal species. Currently, the method proposed by Coesel is the only microalgae-based framework explicitly incorporating rarity, using desmid assemblages to assess the conservation value of aquatic habitats. In this study, we investigated its applicability to the Hungarian aquatic ecosystems using a database containing 379 desmid species from 101 localities, representing 14 habitat types. We calculated the NCV value of all localities. The highest NCV values were found in old bog lakes, marshlands, oxbows and large saline lakes, while reservoirs, large rivers and heavily modified habitats showed lower scores. No significant relationship was detected between the NCV value and the WFD-compliant Ecological Quality Ratio (EQR) metrics, indicating that ecological status metrics are weak predictors of conservation value. Although the desmid-based NCV method provides a promising foundation, its components require refinement and habitat-specific calibration to support more robust conservation assessments.

Source: Hydrobiologia

DOI: 10.1007/s10750-026-06361-2