Overlooked keystone species in conservation plans of fluvial ecosystems in Southeast Europe: a review of native freshwater crayfish species

Abstract

Although a large number of rivers stretches in Southeast Europe (SEE) have a pristine status compared to the rest of Europe, these ecosystems and their freshwater biodiversity are perceptibly threatened. Since crayfish species are known to cover a wide spectrum of ecological functions they are considered as keystone species and ecosystem engineers. Therefore, their decline may substantially impair local biodiversity and ecosystem services. In this manuscript we present a brief overview of the status of the native freshwater crayfish and their habitats in SEE. Different forms of physical habitat degradation as well as invasive alien crayfish species and their pathogens (e.g., Aphanomyces astaci) are simultaneously threatening endangered populations all over SEE. Even though all native crayfish species are listed in the IUCN Red List, so far none of the 33 LIFE rehabilitation projects performed in SEE, has crayfish as target species in their agenda. Furthermore, SEE countries rarely designated Natura 2000 sites for native crayfish. We propose future studies to assess the distribution and functional role of crayfish species in SEE, as well as to develop habitat suitability models for these species during future conservation projects.

People need freshwater biodiversity

“…The cultural importance of freshwater biodiversity in the history of European countries is proven by their appearance in emblems, coats of arms, toponymies, family names, as part of regional sayings, and as figures in legends and stories. Large‐bodied, long‐lived freshwater crayfish, which are ecologically important components of freshwater food webs, ecosystem engineers, and keystone species, are also a regionally important resource for food or fodder (Danilovic et al, 2022; Jussila et al, 2021; Patoka et al, 2016). This importance is highlighted through heraldry; the carapace is associated with protection and the claws with the ability to defend.…”

Cuticular Swabs and eDNA as Non-Invasive Sampling Techniques to Monitor Aphanomyces astaci in Endangered White-Clawed Crayfish (Austropotamobius pallipes Complex)

“…Results of the comparison between sampling protocols (cuticle and swab) in P. clarkii after their housing at the IZSVe aquarium facility. The absolute quantification expressed in PFU (copies/µL) and indicated in scientific notation was reported only for positive samples (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20); samples from 21 to 33 were completely negative. Estimated quantification below LoD level was reported in brown; N/A means no detected amplification or discordance between replicates.…”

“…They control the freshwater community by feeding on benthic fauna and algae, contributing to sedimentation with their burrowing activities. Furthermore, the species are well integrated into the trophic chain, being predated by fish, birds and mammals [12,13]. Therefore, their sudden loss severely compromises freshwater ecosystems [13].…”

“…Furthermore, the species are well integrated into the trophic chain, being predated by fish, birds and mammals [12,13]. Therefore, their sudden loss severely compromises freshwater ecosystems [13]. The distribution of the A. pallipes complex suffers from a rapid contraction and fragmentation.…”

The role of diseases in unifying the health of global estuaries

“…This has already been documented with sea otters in coastal California being affected by pathogens (Ostfeld et al, 2008) and the rocky intertidal zone starfish Pisaster ochraceus (Hajishengallis et al, 2012) falling victim to pathogenic disease outbreaks. There is indication in the literature that if the relationship between keystone species and the microbial ecology of an environment could be elucidated further, there could be essential insights made into the structure of marine pathogenic communities and their interplay with their environment and hosts (Estes and Palmisano, 1974;Ostfeld et al, 2008;Hajishengallis et al, 2012;Danilovićet al, 2022). Such thematic findings, along with the dearth of literature on this interaction, highlight a crucial need for significantly more study.…”