Integrating population genetics and species distribution modelling to guide conservation of the noble crayfish, Astacus astacus, in Croatia

Abstract

The noble crayfish, Astacus astacus, is an indigenous European freshwater species. Its populations show significant declines caused by anthropogenic pressure on its habitats, climate change and the spread of invasive species. Diminishing populations’ trends and loss of genetic diversity highlight the need for effective conservation that will ensure their long-term survival. We combined population genetics and species distribution modelling (SDM) to reveal the impact of climate change and invasive species on the noble crayfish, and to guide future conservation programs of current populations. Our study showed that Croatian populations of A. astacus harbour an important part of species genetic diversity and represent significant genetic reservoir at the European level. The SDM results predicted substantial reductions of suitable habitats for A. astacus by the 2070; only 13% of its current potential distribution is projected to remain stable under pessimistic Representative Concentration Pathway (RCP 8.5) emission scenario. Moreover, most of the populations with high genetic diversity are located in the areas predicted to become unsuitable, and consequently have a high probability of being lost in the future. Further, SDM results also indicated considerable decrease of future habitat suitability for invasive crayfish species in Croatia, suggesting that climate change poses a major threat to already endangered A. astacus. The obtained results help in the identification of populations and areas with the highest conservation value which should be given the highest priority for protection. In order to preserve present diversity in areas that are predicted as suitable, we propose assisted migration and repopulation approaches, for enhancing populations’ size and saving maximum genetic variability. The result of our research emphasizes once again the benefits of multidisciplinary approach in the modern biodiversity conservation.

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

“…High genetic diversity in the Black Sea basin for A. astacus was shown by Schrimpf et al (2014), especially in the western Balkans. Lovrenčić et al (2022) confirmed these findings by showing, that Croatian populations harbour an important part of species genetic diversity and represent significant genetic reservoir at the European level. For P. leptodactylus Maguire et al (2014) found two distinct evolutionary lineages, one Asian and one European.…”

Physiological performance of native and invasive crayfish species in a changing environment: insights from Dynamic Energy Budget models

“…Despite the strong positive impact of temperature increase on maturation and marginally positive impact on reproductive output of the native A. astacus , temperature increase may severely affect its current (limited) distribution range. This has already been observed for A. astacus in Croatia, where most of the populations of highest genetic diversity are positioned within areas predicted to become unsuitable for the species under RCP 4.5 and 8.5 scenarios, and may ultimately lead to loss of these populations ( Lovrenčić et al , 2022 ). Interestingly, the same study also indicated substantial decrease of future habitat suitability for P. leniusculus ( Lovrenčić et al , 2022 ).…”

“…This has already been observed for A. astacus in Croatia, where most of the populations of highest genetic diversity are positioned within areas predicted to become unsuitable for the species under RCP 4.5 and 8.5 scenarios, and may ultimately lead to loss of these populations ( Lovrenčić et al , 2022 ). Interestingly, the same study also indicated substantial decrease of future habitat suitability for P. leniusculus ( Lovrenčić et al , 2022 ). Austropotamobius torrentium , as a highly vulnerable species with the lowest reproductive output under both optimal food availability and increasing temperature and with a similar trend of loss of suitable habitat (Maguire et al, unpublished data), will be especially endangered in the future climate change and invasive crayfish range expansion scenarios.…”

“…Austropotamobius torrentium , as a highly vulnerable species with the lowest reproductive output under both optimal food availability and increasing temperature and with a similar trend of loss of suitable habitat (Maguire et al, unpublished data), will be especially endangered in the future climate change and invasive crayfish range expansion scenarios. This calls for specific conservation measures of assisted migration to climate change refugia, spatially isolated from invasive crayfish spread in the case of A. torrentium , and for a combination of assisted migration and repopulation measures in the case of A. astacus ( Lovrenčić et al , 2022 ).…”

“…Ectotherms such as crayfish are particularly sensitive because the lack of internal temperature control makes them highly dependent on environmental temperature. Deep understanding of effects of temperature is especially important given rapid climate-change driven environmental changes that may affect future invasion patterns and may accelerate population loss of endangered native crayfish species ( Hudina et al , 2011a ; Lovrenčić et al , 2022 ).…”