Representation of obligate groundwater‐dwelling copepod diversity in European protected areas

Groundwaters sustain diverse surface ecosystems and are populated by metazoan species, mostly invertebrates, that provide fundamental ecological functions and are often of prominent conservation value due to narrow endemism and high phylogenetic rarity. Taking advantage of an open-access, Europe-wide, and expert-curated dataset (EGCop) that includes thousands of occurrence records of obligate groundwater-dwelling copepods, we assessed the taxonomic diversity of these groundwater crustaceans in European protected areas. We calculated species richness and beta diversity of copepods in 10 × 10-km cells of the European Biogeographical Regions map. We used statistical matching to select a set of protected and unprotected cells that were comparable in terms of climatic conditions, groundwater habitat diversity, topographic heterogeneity, and glacial history. We compared species richness and beta diversity with protection level and environmental covariates through generalized linear models (GLMs), gradient boosting models (GBMs), and generalized dissimilarity models (GDMs). We also fitted these ecological models with the prematching datasets to analyze diversity patterns regardless of protection level. Species richness was primarily explained by average temperature (bio_10) and precipitation (bio_18) of the warmest quarter in GLMs. Extent of highly productive fissured aquifers had a relatively high percent importance score (up to 30%) in GBMs, which was similar to the score for climatic predictors. Coverage by protected areas contributed practically nothing to species richness in both GLMs and GBMs. Similarly, between-site taxonomic dissimilarity was not consistently higher in protected than in unprotected areas and was only partially explained by environmental variables and geographic distance in GDMs. Of the 517 analyzed species, 205 occurred only in unprotected cells. Our results highlight the need to advance research on groundwater ecosystems and implement targeted conservation actions, including revising protected area boundaries to better encompass karst regions and subterranean biodiversity.