Money Kills Native Ecosystems: European Crayfish as an Example

Abstract

Native European crayfish conservation was triggered by invasion of crayfish plague disease agent, Aphanomyces astaci, starting 1860s in Northern Italy. Resulting crayfish plague epidemics quickly spread over Continental Europe, then to Finland, Sweden and finally, after running amok around Europe, A. astaci was discovered also in Iberian Peninsula, Norway, Ireland, and United Kingdom in 1970s and 1980s. By that time significant proportion of native crayfish stocks had been lost, and while crayfish plague epidemics were still recorded, also industrialization and waterways construction were causing damage to remaining native crayfish stocks. While alien crayfish introductions, at least Faxonius limosus, already gave rise to first wave of crayfish plague epidemics in late 19th century, later in 1960s it was decided that introductions of alien Pacifastacus leniusculus should be initiated to replace native European crayfish populations. Decisions were based on presumed advantages for fishery, suitable habitat requirements and supposed immunity against A. astaci. Furthermore, conservation of native European crayfish species was sidelined and focus shifted toward alien crayfish stocking routine and consumption. Alien crayfish species introductions resulted in repeated waves of crayfish plague epidemics among remaining native crayfish stocks. It was soon discovered that alien crayfish of North American origin were, as suspected, permanent reservoirs for A. astaci, that some of those alien species were losing their resistance against selected strains of A. astaci and struggled in European aquatic ecosystems. In this article, we introduce numerous motives behind grand mistake of introducing alien crayfish species to Europe and then promoting their stocks instead of focusing on conservation of native crayfish species. We outline how false economical, biological and ecologic assumptions were used to justify a hasty introduction of alien crayfish, which has further devastated native crayfish and also permanently changed European aquatic ecosystems, both with disastrous consequences. Lesson to be learnt is that science-based warnings about alien species damage to native ecosystems and native crayfish must be taken with utmost caution. Protection of native European crayfish should be core issue, not commercial activities. Finally, we summarize main threats and actions needed to protect remaining native freshwater crayfish fauna in Europe.

Soil-Related Predictors for Distribution Modelling of Four European Crayfish Species

“…These could be used to design adequate conservation measures by assessing the best local habitat and appropriate inter-populations corridors. Invasive crayfish species may have different abilities to use these soil structures and could benefit from climate change [39]. Thus, the availability of good distributional predictors can be valuable for investigating invasion dynamics, including the carried cray-fish plague pathogen Aphanomyces astaci with the increasing availability of spatial data associated with pathogen strains and virulence [74,75].…”

“…Fragmentation was proved to be one of the main issues in the long run of protecting sensitive species, even in the context of protected areas that may offer appropriate local conditions but failed in ensuring connectivity between populations [31]. Probably one of the most impacting phenomena, the dominance of invasive alien species [32][33][34][35][36][37], accompanied by the carried deadly disease known as crayfish plague [38][39][40], led to dramatic changes in the distributions of European indigenous crayfish species in the last decades [38]. Modern conservation actions should consider an extensive array of factors that should be monitored and controlled.…”

Host-pathogen coevolution drives innate immune response to Aphanomyces astaci infection in freshwater crayfish: transcriptomic evidence

“…Host-pathogen interactions are of high interest in conservation biology, as they not only determine the fate of invasive species, but they also affect the survival of native taxa [11]. Due to its high importance for aquaculture and management, scientists have studied the interaction between freshwater crayfish and their pathogen Aphanomyces astaci for over a century [12]. Still, the coevolutionary aspect of this hostpathogen interaction remains understudied.…”

“…Haplogroup A contains strains of unequal virulence (ranging from non-virulent to highly virulent), while haplogroups B, D and E are usually characterized by high virulence [17,22,23]. Despite the high susceptibility of native European crayfish species towards the crayfish plague disease agent, latent crayfish plague infections without mass mortalities have been reported for several species infected with low virulent A. astaci strains of haplogroup A [12], suggesting the presence of an ongoing dynamic coevolutionary process. However, the foundation of this naturally occurring resistance to A. astaci remains unclear.…”

Controlled Infection Experiment With Aphanomyces astaci Provides Additional Evidence for Latent Infections and Resistance in Freshwater Crayfish

“…The second wave was caused by multiple introductions of different species of North American crayfish (Alderman, 1996). It is believed that each of them carried its own specific haplogroup of A. astaci, resulting in the introduction into Europe of three new haplogroups: B, D, and E (Huang et al, 1994;Diéguez-Uribeondo et al, 1995;Kozubíková et al, 2011;Makkonen et al, 2018;Jussila et al, 2021). North American crayfish are resistant against A. astaci and can act as reservoirs for the pathogen (Unestam and Weiss, 1970;Unestam and Nylund, 1972;Alderman, 1996).…”