Introduction Of Crayfish Research Articles

Long‐Term Declines in Body Size of the Invasive Rusty Crayfish (Faxonius rusticus) in Temperate Lakes

ABSTRACT Invasive species often experience phenotypic change during the invasion process. For example, many invasive species are larger in their non‐native than native ranges, but some invasive species experience body size declines with time since invasion. Mechanisms of these phenotypic changes are poorly known, likely due to a paucity of long‐term datasets and complex interactions among abiotic and biotic factors that affect body size over time. We use a long‐term dataset (1980–2020) in 17 lakes of Wisconsin, United States to investigate trends in body size for an invasive species, the rusty crayfish (Faxonius rusticus). We relate F. rusticus body size to crayfish relative abundance as catch‐per‐unit effort (CPUE) from baited trapping, as well as modelled lake temperatures and pelagic primary productivity, using a structural equation model (SEM). Our use of an SEM allowed us to investigate the direct effect of time on F. rusticus on body size, as well as indirect effects through factors like warming of lakes due to climate change. We found that F. rusticus body size has declined by 10% over the past four decades in our study lakes, from a mean of 36.6 mm total carapace length in 1980 to 32.8 mm in 2020. Faxonius rusticus individuals were larger when lakes were warmer, but the overall effect of time on declining F. rusticus body size was stronger than this predictor. Relative abundance as CPUE had no effect on F. rusticus body size, rejecting a role for density dependence in explaining adult body size of this invasive crayfish. Declining F. rusticus body sizes have accompanied population declines of this invasive crayfish in some Wisconsin lakes, and both trends provide potential for post‐invasion ecosystem recovery. As one example, smaller F. rusticus individuals may be less effective or active predators on fish nests. By contrast, declining F. rusticus body size may also create opportunities for serial or over‐invasion by future crayfish invaders, sustaining a need to discourage crayfish introductions to this region.

World of Crayfish™: a web platform towards real-time global mapping of freshwater crayfish and their pathogens

Freshwater crayfish are amongst the largest macroinvertebrates and play a keystone role in the ecosystems they occupy. Understanding the global distribution of these animals is often hindered due to a paucity of distributional data. Additionally, non-native crayfish introductions are becoming more frequent, which can cause severe environmental and economic impacts. Management decisions related to crayfish and their habitats require accurate, up-to-date distribution data and mapping tools. Such data are currently patchily distributed with limited accessibility and are rarely up-to-date. To address these challenges, we developed a versatile e-portal to host distributional data of freshwater crayfish and their pathogens (using Aphanomyces astaci, the causative agent of the crayfish plague, as the most prominent example). Populated with expert data and operating in near real-time, World of Crayfish™ is a living, publicly available database providing worldwide distributional data sourced by experts in the field. The database offers open access to the data through specialized standard geospatial services (Web Map Service, Web Feature Service) enabling users to view, embed, and download customizable outputs for various applications. The platform is designed to support technical enhancements in the future, with the potential to eventually incorporate various additional features. This tool serves as a step forward towards a modern era of conservation planning and management of freshwater biodiversity.

An overview of recent introductions of non-native crayfish (Crustacea, Decapoda) into inland water systems in Israel

An overview of recent introductions of non-native crayfish (Crustacea, Decapoda) into inland water systems in Israel

Diversity and distribution of Aphanomyces astaci in a European hotspot of ornamental crayfish introductions

Ornamental trade has become an important introduction pathway of non-native aquatic species worldwide. Correspondingly, there has been an alarming increase in the number of established crayfish of aquarium origin in Europe over the previous decade. The oomycete Aphanomyces astaci, the pathogen causing crayfish plague responsible for serious declines of European crayfish populations, is dispersed with introduced North American crayfish. The role of ornamental taxa in introducing and spreading different genotypes of this pathogen in open waters remains unclear. We investigated the distribution, prevalence, and diversity of A. astaci in Budapest, Hungary, which became a hotspot of aquarium crayfish introductions. Their establishment in this area was facilitated by locally abundant thermal waters. We screened for A. astaci in six host taxa from 18 sites sampled between 2018 and 2021: five cambarids (Cambarellus patzcuarensis, Faxonius limosus, Procambarus alleni, P. clarkii, P. virginalis) and one native astacid (Pontastacus leptodactylus). The pathogen was confirmed at five sampled sites in four host taxa: P. virginalis, P. clarkii, F. limosus, and for the first time in European open waters also in P. alleni. Genotyping was successful only in individuals from two different brooks where multiple host species coexisted but revealed unexpected patterns. Mitochondrial B-haplogroup of A. astaci, previously usually reported from Pacifastacus leniusculus or infected European species, was detected in P. virginalis at both sites, and in both F. limosus and P. virginalis sampled from a thermally stable tributary of Barát brook in 2018. In contrast, A-haplogroup of A. astaci was detected in coexisting F. limosus, P. virginalis and P. clarkii sampled in the same watercourse just a few hundred meters downstream in 2020. Additional genotyping methods indicated that a previously unknown A. astaci strain was associated with the latter haplogroup. One P. virginalis individual from 2020 was apparently co-infected by strains representing both mitochondrial haplogroups. The results indicated multiple sources of A. astaci in Budapest, likely directly associated with the introduction of ornamental species, interspecific transmission of this pathogen among ornamental hosts, and potential for a quick spatial or temporal turnover of dominant A. astaci strains at a certain locality. This highlights that in regions with high richness of potential A. astaci hosts, host taxon/pathogen genotype combinations become unpredictable, which might prevent reliable genotyping of pathogen sources in local crayfish mass mortalities.

Managing Pathways for Introduction of Alien Crayfish: Evaluation of a Midwestern State's Regulations on the Pet Industry

The increasing worldwide popularity of the aquatic pet trade causes widespread transport and introduction of alien species, including crayfish (Astacidea), into fisheries. Thirty crayfish species have invaded North America, affecting native species and changing ecosystems. Growing numbers of crayfish introductions are linked to the pet trade, and this pathway increasingly requires attention from natural resource managers. The Missouri Department of Conservation implemented regulations in 2014 to restrict pet store crayfish sales. We surveyed all Missouri pet stores in 2019 to estimate regulation compliance. Undercover enforcement agents visited stores and assessed crayfish sales by inspecting livestock and interviewing owners/employees. Simultaneously, we conducted a comparative survey of Ohio stores, where minimal regulations exist. Crayfish, including three alien species, were illegally sold at 15.5% of Missouri stores. In Ohio, 63% of stores sold crayfish, including three alien species. The Missouri regulations appear effective for managing and reducing pet store sales of potentially invasive crayfish.

Co-culture of red swamp crayfish Procambarus clarkia influenced glycoside hydrolase families and fungal communities in the rice-paddy soils

Integrated rice–crayfish farming has expanded rapidly, and an in-depth understanding of this model is urgently required. In the present study, metagenomics and real-time polymerase chain reaction were carried out to determine whether and how the introduction of the red swamp crayfish Procambarus clarkia affected glycoside hydrolase (GH) families and the abundance and community composition of fungi in soils. Investigations comprised the ecosystems of rice–crayfish co-culture fields, crayfish culture ponds, and rice paddy fields. Further, we sought to investigate the influence of the fungal community on bacterial chitinase gene abundance. The results showed that although rice cultivation induced variations in GH families and fungal communities in rice paddy soils, the introduction of crayfish was the main factor responsible for these variations. Additionally, the proliferation of bacteria with chitinase genes was not induced by the crayfish exoskeleton (in the form of living animals) but by the abundance of fungi in the soils. Therefore, bacterial chitinase in soils may not affect the exoskeleton of living crayfish but is likely the main regulator of the abundance of soil fungi. The impact of crayfish on fungal diversity was likely due to direct biological effects, while its inhibitory effect on fungal abundance was mainly attributed to the low nitrogen content in soils.

Nothing can go wrong–Introduction of alien crayfish to Europe

Nothing can go wrong–Introduction of alien crayfish to Europe

The King's aquatic desires: 16th‐century fish and crayfish introductions into Spain

AbstractHumans have introduced species out of their native areas for millennia, and characterising these historical introductions can provide insights into the long‐term progress of invasion processes. Here, archival sources and other historical documents are used to describe the motivations, negotiations and actions leading to fish and crayfish introductions into Spain in the second half of the 16th century. King Philip II of Spain brought to the Iberian Peninsula several gardening customs from central Europe, including the construction of fish ponds and their stocking with different aquatic species, many of which were naturally absent from Iberia. These interests led to the introduction of pike (Esox Lucius, Esocidae), common carp (Cyprinus carpio, Cyprinidae), tench (Tinca tinca, Cyprinidae) and Italian crayfish (Austropotamobius italicus, Astacidae). Historical documents allowed describing introduction events, their early management and their outcomes with high temporal, spatial and taxonomic precision. These results introduce a centuries‐long view on the history of the presence of these introduced species in the Iberian Peninsula, where they have all been successful invaders in different historical periods. This work exemplifies the large potential of archival documents to inform about long‐term human–nature relationships, with implications for present‐day environmental management (e.g. setting conservation targets). However, this potential has been only sparsely explored, arguably due to the lack of interactions between humanities and natural sciences. Interdisciplinary historical ecology research should be promoted in order to build robust and applicable knowledge on the long‐term variability of ecosystems and their biota.

Ecological and potential socioeconomic impacts of two globally-invasive crayfish

Quantifying the impacts of invasive species, relative to native analogues, is crucial for management and policy development. Two freshwater crayfish species of global concern, Cherax quadricarinatus and Procambarus clarkii, have established populations across Africa. Negative impacts on native biodiversity and socioeconomic impacts have been documented in other continents; however, there is a paucity of information on impacts from Africa and for C. quadricarinatus. To fill this literature gap, this study used laboratory experiments to determine potential ecological and socioeconomic impacts conferred by the crayfish species relative to a functionally similar native analogue, the river crab Potamonautes perlatus, on two static, but different resources. Consumption rates were derived for the three focal species consuming the macrophyte Potamogeton nodosus and dead Oreochromis mossambicus under different temperatures regimes (19 °C and 28 °C), representing summer and winter seasons in Southern Africa, with maximum feeding rate used to infer impact. Potamogeton represents ecologically-important nutrient cycling macrophytes, as well as crucial habitat for juvenile fish, whereas dead O. mossambicus was used as proxy for fish catches in artisanal gillnet fisheries often scavenged by crayfish. Consumption of both resources by all the decapods increased with temperature. However, the two invasive crayfish showed different impact trends where P. clarkii had a significantly higher consumption of macrophytes than the other two decapods regardless of temperature and the same trends seen, but for C. quadricarinatus scavenging on fish. Crayfish introductions clearly have potential for highly destructive ecological and socioeconomic impacts to invaded systems as compared to the native crabs. The disparity between resource use emphasises the necessity to use appropriate geographical and species-specific contexts to avoid erroneous conclusions from generalised risk assessments. Derived feeding rates can be used for rapid impact assessments and comparisons in other invasion cores.

Hemolymph Glycemia as an Environmental Stress Biomarker in the Invasive Red Swamp Crayfish (Procambarus clarkii)

AbstractSeveral freshwater crayfish species, including Procambarus clarkii, are both ecologically important and commercially important benthic macroinvertebrates, remarkable for their potential to adapt and reproduce but also for their unique abilities to face distinct abiotic and biotic environments and become successful invaders. While much work has been done to study crayfish introductions, less focus has been given to how crayfish cope with pollution and other environmental stressors, in terms of physiological responses, and whether crayfish responses can be used to assess the effective state of their living environment. Here, we used a mixed approach combining laboratory experiments with field data to validate the use of hemolymph glucose as a relevant biomarker of red swamp crayfish (Procambarus clarkii) stress response. Three meaningful sampling locations were chosen across southern Portugal that are representative of different environments where crayfish live and are frequently captured for human consumption but also correspond to different pollution levels. To reference field measurements of glucose levels, we performed two lab-based experiments: (a) crayfish were exposed to different levels of stress (stress challenge) and (b) crawfish were exposed to a maze dispersal test, with or without water. Crayfish glucose levels were responsive to induced stress but were not correlated with dispersal efforts. Wild crayfish's body condition and stress levels responded differently to environmental conditions, with more challenged individuals showing higher glycemia levels but similar body condition. The glucose levels of the more stressed wild crayfish were visually similar to lab-based crayfish subjected to the higher stress levels (electric shocks), while the levels of glucose of crayfish at the less polluted site corresponded to those measured before the start of the challenge (baseline). The maintenance of high levels of glycemia in crayfish inhabiting more challenging habitats is revealing of their higher energetic demand state. Since P. clarkii ia globally distributed and easily sampled invasive species, quantifying its hemolymph glucose levels can be a particularly useful proxy for assessing environmental quality.

The dilution effect in a freshwater mutualism: Impacts of introduced host species on native symbionts

AbstractThe dilution effect was originally proposed to describe the negative effect of increased host diversity on parasite or pathogen abundance; with greater host diversity, parasite or pathogen levels per host are predicted to be lower due to a higher probability of dispersing parasites or pathogens encountering noncompetent hosts. Dilution effects could occur in many mutualisms if dispersing symbionts encounter hosts that vary in their competence. Introduced, non‐native hosts can change the community competence of a local group of host species. Crayfish introductions are occurring world‐wide and these introductions are likely disrupting native crayfish‐symbiont systems. Branchiobdellidan symbionts declined on native Cambarus crayfish co‐occurring with non‐native Faxonius crayfish in the New River watershed, USA. We performed an experiment investigating the effect of host density (1 vs. 2 native hosts) and host diversity (1 native host and 1 introduced host) on branchiobdellidan abundance. The introduced Faxonius cristavarius is a noncompetent host for these worms. Six C. ingens were stocked on a Cambarus chasmodactylus in each treatment and worm numbers were followed over 34 days. Worm numbers decreased over time on C. chasmodactylus alone and in the treatment in which a C. chasmodactylus was paired with an F. cristavarius. Worm numbers remained highest in the 2 C. chasmodactylus treatment. There was no effect of host diversity on worm reproduction. Crayfish invasions may have negative effects on mutualistic symbionts depending on the competence of introduced hosts. Loss of native symbionts is one of the potential hidden, negative effects of invasions on native freshwater diversity.

Using eDNA to simultaneously detect the distribution of native and invasive crayfish within an entire country

The introduction of invasive crayfish has led to a decline of many European native species of crayfish across their range. In this study, novel duplex assays for all crayfish occurring in Switzerland were developed. We aimed to identify the distribution of the seven species using a traditional trap surveillance method as well by collecting water samples to detect eDNA by species-specific quantitative real-time PCR. We reveal our overall experience in finding optimal field and laboratory techniques to discover the distribution and abundance of native and invasive species in order to enhance knowledge of early invasive species invasion and highlight important pockets of populations where native species remain, for implementation of conservation strategies. Using eDNA, important populations of native noble and white-clawed crayfish were revealed in multiple waters across various cantons. The successful identification of native and invasive crayfish species in Switzerland using eDNA can be applied to future nationwide projects. This method which has the ability to detect all species simultaneously across an entire country, will allow an improvement in freshwater crayfish conservation management.

Money Kills Native Ecosystems: European Crayfish as an Example

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. astaciwas 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 leastFaxonius limosus, already gave rise to first wave of crayfish plague epidemics in late 19th century, later in 1960s it was decided that introductions of alienPacifastacus leniusculusshould be initiated to replace native European crayfish populations. Decisions were based on presumed advantages for fishery, suitable habitat requirements and supposed immunity againstA. 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 forA. astaci, that some of those alien species were losing their resistance against selected strains ofA. astaciand 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.

Real-Time PCR Assays for Rapid Identification of Common Aphanomyces astaci Genotypes

The oomyceteAphanomyces astaciis the etiologic agent of crayfish plague, a disease that has seriously impacted the populations of European native crayfish species. The introduction of non-indigenous crayfish of North American origin and their wide distribution across Europe have largely contributed to spread of crayfish plague in areas populated by indigenous crayfish. TrackingA. astacigenotypes may thus be a useful tool for investigating the natural history of crayfish plague in its European range, as well as the sources and introduction pathways of the pathogen. In this study, we describe the development of real-time PCR TaqMan assays aiming to distinguish the five genotype groups ofA. astaci(A–E) previously defined by their distinct RAPD patterns. The method was evaluated using DNA extracts from pureA. astacicultures representing the known genotype groups, and fromA. astaci-positive crayfish clinical samples collected mostly during crayfish plague outbreaks that recently occurred in Central Italy and Czechia. The assays do not cross-react with each other, and those targeting genotype groups A, B, D, and E seem sufficiently specific to genotype the pathogen from infected crayfish in the areas invaded byA. astaci(particularly Europe). The unusualA. astacigenotype “SSR-Up” documented from crayfish plague outbreaks in Czechia and chronically infectedPontastacus leptodactylusin the Danube is detected by the group B real-time PCR. The assay originally developed to detect group C (one not yet documented from crayfish plague outbreaks) showed cross-reactivity withAphanomyces fennicus; theA. astacigenotype “rust1” described in the United States fromFaxonius rusticusis detected by that assay as well. Analyses of additional markers (such as sequencing of the nuclear internal transcribed spacer or mitochondrial ribosomal subunits) may complement such cases when the real-time PCR-based genotyping is not conclusive. Despite some limitations, the method is a robust tool for fast genotyping ofA. astacigenotype groups common in Europe, both during crayfish plague outbreaks and in latent infections.

Hungary: a European hotspot of non-native crayfish biodiversity

There is a long history of crayfish introductions in Europe and numbers keep increasing. In Hungary, spiny-cheek crayfish Faxonius limosus, signal crayfish Pacifastacus leniusculus, red swamp crayfish Procambarus clarkii, marbled crayfish P. virginalis and Mexican dwarf crayfish Cambarellus patzcuarensis have become established. Here we report on monitoring at two localities with novel crayfish assemblages closely linked to releases associated with the pet trade. Florida crayfish Procambarus alleni were recorded from the Gombás brook near Vác living in syntopy with the established spiny-cheek crayfish. Dozens of Florida crayfish individuals including egg-carrying females have been detected. The short lifespan of this species and its documented presence including two overwintering in at least two years suggests possible establishment. However, the lack of juvenile records calls for further monitoring as long-term propagule pressure cannot be ruled out. We also identified a single marbled crayfish in the Danube floodplain at the end of the monitoring campaign. The second locality (Városliget thermal pond in Budapest) harbours an even more diverse crayfish assemblage. Here, we identified numerous red swamp and marbled crayfish in syntopy with dozens of monitored redclaws Cherax quadricarinatus and seven individuals of New Guinean Cherax species − C. holthuisi, C. snowden, as well as two scientifically undescribed species. These findings clearly indicate the attractiveness of urban and, especially, thermal waters for the release of even expensive aquatic pets and highlight the hitherto poorly known biodiversity of New Guinean crayfish species.

Introduced alien signal crayfish (Pacifastacus leniusculus) in Finland − uncontrollable expansion despite numerous crayfisheries strategies

In Finland, massive signal crayfish introductions started towards the end of 1980s, with an estimated total of 2.2 million signal crayfish been stocked before year 2016. During that period, Finnish fisheries authorities have implemented three national management strategies setting guidelines for the crayfish introductions. The main aims of the strategies have been conservation of native noble crayfish stocks and a controlled spreading of the alien signal crayfish within a designated region. In this study, we report the current distribution of signal crayfish in Finland in comparison to the guidelines set in these three national strategies. The present distribution area of the signal crayfish covers most of the Southern Finland. The signal crayfish has been introduced with a stocking permits to over 480 water bodies. In addition, there have been numerous stockings without permits, which are often next to the region designated for the signal crayfish. Based on the results, we conclude that crayfish management strategies adopted in Finland have only had limited effect on the spread of signal crayfish. We presume that main causes for the uncontrolled spreading of the signal crayfish in Finland have been lack of strict official supervision and general lack of awareness about the risks associated with the alien species spreading.

The use of Chara spp. (Charales: Characeae) as a bioindicator of physico‐chemical habitat suitability for an endangered crayfish Austropotamobius pallipes in lentic waters

Abstract Austropotamobius pallipes is an endangered decapod attracting much attention in freshwater conservation programmes. In some cases population transfers or reintroductions are carried out in lentic ecosystems such as ponds or quarries. Such conservation actions require rapid, low cost and powerful tools to census suitable habitat. Some species of the Characeae family (Chara spp.), share ecological needs with A. pallipes and are proposed as bioindicators of suitable habitat. Chara species were tested, among other plants, as bioindicators, and to see whether Chara species are a stronger indicator than water chemistry. The Pinail Nature Reserve, with 3000 permanent ponds, is inhabited by white‐clawed crayfish probably introduced historically into ponds used for fish production. This allows a replicated study of suitable habitats where plant communities are bioindicators of crayfish presence. Crayfish presence is associated with Chara species (such as Chara aspera, Chara virgata, Chara fragifera, Chara polyacantha and Chara vulgaris). Austropotamobius pallipes is present in ponds with Chara spp. (N = 10/10) while other ponds without crayfish are lacking charophytes (N = 1/23). Algae of the genus Chara are thus a simple and low‐cost additional tool for determining suitable habitat for crayfish introductions within enclosed waters protected from exotic invasive species and disease. Cladium mariscus also appears to be another useful bioindicator for crayfish habitat.

ザリガニ類(ウチダザリガニ,メキシコザリガニ,マロン,レッドクロー)の移入に関する考察

ザリガニ類(ウチダザリガニ,メキシコザリガニ,マロン,レッドクロー)の移入に関する考察

First record of the invasive Australian redclaw crayfish <i>Cherax quadricarinatus</i> (von Martens, 1868) in the Crocodile River, Kruger National Park, South Africa

The redclaw crayfish Cherax quadricarinatus (von Martens, 1868), a robust freshwater crayfish native to Australia and Papua New Guinea, has now been recorded from the Kruger National Park (KNP). Previously absent from the Crocodile River, SAN Parks received a report in February 2016 of redclaw crayfish below the Van Graan Dam on the border of the KNP. Here, we provide evidence of the presence of redclaw crayfish in the Crocodile River. A better understanding of the redclaw crayfish distribution, habitat preferences, rate of spread and impacts on the local aquatic ecosystems in the Crocodile River is urgently required to develop mitigation strategies that minimise the spread of this invasive crayfish in the KNP and the Komati Catchment. The negative impacts of global crayfish introductions justify efforts to discourage further introductions and prevent their secondary spread.Conservation implications: A better understanding of the redclaw crayfish distribution, habitat preferences, rate of spread and impacts on the local aquatic ecosystems in the Crocodile River is urgently required to develop mitigation strategies that minimise the spread of this invasive crayfish in the Kruger National Park and the Komati Catchment.

Predictions of marbled crayfish establishment in conurbations fulfilled: Evidences from the Czech Republic

AbstractThe marbled craynsn (