Climate Warming as a Possible Trigger of Keystone Mussel Population Decline in Oligotrophic Rivers at the Continental Scale

Abstract

The effects of climate change on oligotrophic rivers and their communities are almost unknown, albeit these ecosystems are the primary habitat of the critically endangered freshwater pearl mussel and its host fishes, salmonids. The distribution and abundance of pearl mussels have drastically decreased throughout Europe over the last century, particularly within the southern part of the range, but causes of this wide-scale extinction process are unclear. Here we estimate the effects of climate change on pearl mussels based on historical and recent samples from 50 rivers and 6 countries across Europe. We found that the shell convexity may be considered an indicator of the thermal effects on pearl mussel populations under warming climate because it reflects shifts in summer temperatures and is significantly different in viable and declining populations. Spatial and temporal modeling of the relationship between shell convexity and population status show that global climate change could have accelerated the population decline of pearl mussels over the last 100 years through rapidly decreasing suitable distribution areas. Simulation predicts future warming-induced range reduction, particularly in southern regions. These results highlight the importance of large-scale studies of keystone species, which can underscore the hidden effects of climate warming on freshwater ecosystems.

Integrative taxonomy, biogeography and conservation of freshwater mussels (Unionidae) in Russia

“…Furthermore, a variety of old synonyms for several species and genera were resurrected as valid names using minute differences in the curvature of the shell frontal section 25,64,66 . However, the shell convexity is strongly influenced by habitat parameters and climatic factors and cannot be used as a diagnostic character 3,5,9,[26][27][28]31,35,38 . A growing body of research critically reassessing the comparatory method in and outside of Russia has discredited its usage for taxonomy, and the last "comparatory" species, Middendorffinaia alimovi (=M.…”

“…It is likely that environment-induced shifts in the shell shape can be traced in species with extremely high levels of conchological variability such as Anodonta anatina, Beringiana beringiana, Buldowskia suifunica, B. shadini, Middendorffinaia mongolica, and Nodularia douglasiae. Furthermore, the shell convexity that was used to delineate comparatory taxa actually reflects shifts in summer temperatures and can be applied as a sensitive and low-cost indicator of climate changes 3,94 .…”

Freshwater mollusks from Neogene-Quaternary Dniester and Prut riverine deposits as indicator paleoenvironments: chemical composition of shells and its palaeoecological interpretation

“…Modern global eutrophication of watercourses, caused by anthropogenic pollution and climate change in the direction of warming (Fritts et al 2017, Lundquist et al 2019, leads to the replacement of pearl mussels of the family Margaritiferidae by more eurybiont species of the family Unionidae in the benthic communities of European oligotrophic rivers. These processes are similar to those deduced for the Neogene-Quaternary watercourses of the Prut and Dniester basins, but proceed at a much faster pace.…”

Peer Review #2 of "The Global Museum: natural history collections and the future of evolutionary science and public education (v0.1)"

“…The Gothenburg Natural History Museum (GNM) malacological collections have benefitted tremendously by citizen science efforts with devoted ('advanced') amateurs donating their often well-curated private collections. Based on these collections, which can be considered 'environmental archives ', Bolotov et al (2018) could infer from freshwater pearl mussel collections that morphology has changed in time correlated to environmental alteration and climate change.…”