Global environmental goals mandate the expansion of the protected area network to halt biodiversity loss. The European Union’s Natura 2000 network covers 27.3% of the terrestrial area of Greece, one of the highest percentages in Europe. However, the extent to which this network protects Europe’s biodiversity, especially in a biodiverse country like Greece, is unknown. Here, we overlap the country’s Natura 2000 network with the ranges of the 424 species assessed as threatened on the IUCN Red List and present in Greece. Natura 2000 overlaps on average 47.6% of the mapped range of threatened species; this overlap far exceeds that expected by random networks (21.4%). Special Protection Areas and Special Areas of Conservation (non-exclusive subsets of Natura 2000 sites) overlap 33.4% and 38.1% respectively. Crete and Peloponnese are the two regions with the highest percentage of threatened species, with Natura 2000 sites overlapping on average 62.3% with the threatened species’ ranges for the former, but only 30.6% for the latter. The Greek ranges of all 62 threatened species listed in Annexes 1 and II to the Birds and Habitats Directives are at least partially overlapped by the network (52.0%), and 18.0% of these are fully overlapped. However, the ranges of 27 threatened species, all of which are endemic to Greece, are not overlapped at all. These results can inform national policies for the protection of biodiversity beyond current Natura 2000 sites.

Disentangling the main drivers of species richness and community composition is a central theme in ecology. Freshwater biodiversity patterns have been poorly explored; yet, it has been shown that different freshwater biota have different, often contrasting responses to environmental gradients. In this study, we investigated the relative contribution of geographical and environmental (habitat-, climate- and water quality-related) factors/gradients in shaping the α- and β-diversity patterns of macrophytes and fish in sixteen natural freshwater lakes of an unexplored Balkan biodiversity hotspot, the Southern Balkan Peninsula. We employed generalized linear modeling to identify drivers of α-diversity, and generalized dissimilarity modeling to explore commonalities and dissimilarities of among-biota β-diversity. Species richness of both biota was significantly associated with lake surface area, whereas macrophytes had an inverse response to altitude, compared to fish. Both species turnover and nestedness significantly contributed to the total β-diversity of macrophytes. In contrast, species turnover was the most significant contributor to the total fish β-diversity. We found that the compositional variation of macrophytes is primarily limited by dispersal and ultimately shaped by environmental drivers, resulting in spatially structured assemblages. Fish communities were primarily shaped by altitude, highlighting the role of species sorting. We conclude that among-biota diversity patterns are shaped by different/contrasting factors, and, thus, effective/sustainable conservation strategies should encompass multiple aquatic biota.

The Mediterranean Sea (MED) is prone to species’ introductions, induced by human activities and/or climate change. Recent studies focus on the biological traits that result in such introductions, yet on a single-area-type approach. Here, we used, analyzed, and compared biological traits derived from FishBase for MED, non-indigenous (NIS) and neonative (NEO) in the Mediterranean, and adjacent Atlantic (ATL) and Red Sea (RS) species. A quantitative trait-based analysis was performed using random forest to determine the importance of traits in the successful establishment in the Mediterranean. MED fishes were mainly demersal, slow growing and small-medium sized, preferring intermediate temperatures. Conversely, ATL were mainly deep-dwelling species, preferring low temperatures. RS and NIS were predominantly reef-associated, thermophilus, and stenothermic. NEO species were stenothermic with preference to intermediate-high temperatures. Omnivores with preference to animals was the most common trophic group among regions. MED species exhibited higher phylogenetic uniqueness (PD₅₀) compared to RS and NIS, indicating that they have long ancestral branches and few descendants. Preferred temperature, habitat type preference and maximum reported length (L_max) and infinite length (L_inf) were the most important predictors in the establishment process. Overall, the results presented here could serve as a baseline for future research, especially by using more refined and/or additional biological trail estimates.