Native Crayfish Research Articles

ОСНОВНЫЕ ПОЛОЖЕНИЯ СТРАТЕГИИ ВОСПРОИЗВОДСТВА РЕСУРСОВ РОССИЙСКИХ РЕЧНЫХ РАКОВ (ASTACINAE LATREILLE, 1802)

Strategy of reproduction of resources of native crayfish subfamily Astacinae (noble crayfish ( Astacus astacus (L.)), narrow-clawed crayfish ( Pontastacus leptodactylus (Esch.)), Kuban crayfish ( P. cubanicus (Birstein & Winogradov, 1934)) was developed in the conditions of reduction of the number of these valuable species and loss of many commercial water-bodies in the European part of Russia. The strategy was developed taking into account the achievements of Western European countries and Russia in the field of restoration of native astacinae resources in the natural water-bodies and in conditions of cultivation. Reproduction of natural resources of the Russian crayfish should be carried out stage by stage in the territories with favorable ecological and hydrographic conditions for their breeding. Provisions recommended to follow include: selection of the territories favorable for crayfish breeding; preparation of the list of water-bodies suitable for formation of sites with high crayfish productivity; arranging crayfish hatcheries (astacological centers) for receiving crayfish stocking material; creating crayfish reproduction grounds by means of intruding there seeding material from the fish farms. Cultivated resources of crayfish, such as reserved populations, domesticated forms, new-spawning stock of crayfish, groups of breeds and others, are practically absent in Russia. Creating specialized resources for crayfish cultivating (ponds, cages, tank-basins) will allow to carry out selective and genetic researches, to develop technologies of crayfish growing for food production, etc. Solutions for funding actions for reproduction of Astacinae resources and for their legal protection have been proposed.

Native European branchiobdellids on non-native crayfishes: Report from the Czech Republic

Invasive alien species present a global threat to biodiversity, particularly where pathogens and symbionts are involved. Non-native crayfish species can increase their impact on the host ecosystem through introductions of symbiotic fauna. Conversely, non-native crayfishes could serve as hosts for native epibionts, thus substituting for disappearing native crayfishes as well. Here we report the presence of native branchiobdellids on naturalized populations of non-native crayfish Orconectes limosus and Pacifastacus leniusculus living in sympatry with native Astacus astacus. The native crayfish species probably served as a source of Branchiobdella spp. for non-native crayfishes. Two species of Branchiobdella (B. parasita and B. pentadonta) were found on P. leniusculus while only B. parasita was found on O. limosus. The level of colonization of inspected specimens and species was also evaluated. The mean number of branchiobdellids found on P. leniusculus and O. limosus was 26.0±15.9, and 64.8±27.7, respectively. Orconectes limosus was more heavily colonized by Branchiobdella despite being significantly smaller than P. leniusculus. Non-native species were corroborated as suitable to host the native epibionts.

Recent acute crayfish mortality reveals Aphanomyces astaci presence in Bosnia and Herzegovina.

Although the introduction of the crayfish plague pathogen Aphanomyces astaci to Europe is responsible for substantial declines in native crayfish populations throughout the whole continent, its presence has never been officially confirmed in many European regions, including most of the Balkan Peninsula. We demonstrate that the recent crayfish mortality observed in Bosnia and Herzegovina (Mostarsko blato karst field, Neretva river drainage) was caused by A. astaci. The causative strain is known only from European crayfish, indicating that A. astaci poses a threat to native species in this region, even in the absence of its main vectors, the North American crayfish.

Behavior and season affect crayfish detection and density inference using environmental DNA.

Although the presence/absence of aquatic invertebrates using environmental DNA (eDNA) has been established for several species, inferring population densities has remained problematic. The invasive American signal crayfish, Pacifastacus leniusculus (Dana), is the leading cause of decline in the UK's only native crayfish species, Austropotamobius pallipes (Lereboullet). Methods to detect species at low abundances offer the opportunity for the early detection, and potential eradication, of P. leniusculus before population densities reach threatening levels in areas occupied by A. pallipes. Using a factorial experimental design with aquaria, we investigated the impacts of biomass, sex ratio, and fighting behavior on the amount of eDNA released by P. leniusculus, with the aim to infer density per aquarium depending on treatments. The amount of target eDNA in water samples from each aquarium was measured using the quantitative Polymerase Chain Reaction. We show that the presence of eggs significantly increases the concentration of crayfish eDNA per unit of mass, and that there is a significant relationship between eDNA concentration and biomass when females are egg‐bearing. However, the relationship between crayfish biomass and eDNA concentration is lost in aquaria without ovigerous females. Female‐specific tanks had significantly higher eDNA concentrations than male‐specific tanks, and the prevention of fighting did not impact the amount of eDNA in the water. These results indicate that detection and estimate of crayfish abundance using eDNA may be more effective while females are ovigerous. This information should guide further research for an accurate estimation of crayfish biomass in the field depending on the season. Our results indicate that detection and quantification of egg‐laying aquatic invertebrate species using eDNA could be most successful during periods when eggs are developing in the water. We recommend that practitioners consider the reproductive cycle of target species when attempting to study or detect aquatic species using eDNA in the field.

A crayfish survey of the fishing creek watershed in northeastern Pennsylvania suggests widespread prevalence of a nonindigenous species and the absence of a native congener

Abstract Introduction of nonindigenous crayfish species impacts freshwater ecosystems and can result in displacement of native crayfish. The crayfish Orconectes limosus and Cambarus bartonii are native to the Susquehanna River drainage in Pennsylvania. However, several nonindigenous crayfish have become established in this drainage. No comprehensive survey exists on crayfish species within the Fishing Creek watershed. Historic records report O. limosus and C. bartonii in this watershed; however, recent point surveys have documented the presence of the nonindigenous crayfish O. obscurus. We sampled crayfish in 15 sites from the lower reaches of Fishing Creek through its headwaters and major tributaries. We collected a total of 484 crayfish, representing the species O. obscurus and C. bartonii. We found O. obscurus within much of Fishing Creek and some tributaries, but absent from the upper reaches of the watershed, possibly due to a series of dams. C. bartonii were primarily found in the upper portions of the Fishing Creek watershed, but also found at low abundance with O. obscurus in the central portions of the watershed and in a small, first order tributary. We collected no O. limosus specimens in our samples, suggesting local extirpation via displacement by O. obscurus, as has been reported elsewhere.

Resistance to the crayfish plague, Aphanomyces astaci (Oomycota) in the endangered freshwater crayfish species, Austropotamobius pallipes.

The pathogen Aphanomyces astaci Schikora 1906 is responsible for the decline of the native crayfish species of Europe, and their current endangered status. This pathogenic species is native to North America and only colonizes aquatic decapods. The North American crayfish species have a high resistance to this pathogen, while species from other regions are highly susceptible. However, recent field and laboratory observations indicate that there might exist some populations with resistance against this disease. The objective of this study was to test the susceptibility of 8 selected native European crayfish populations of Austropotamobius pallipes Lereboullet 1858 from the Pyrenees. We challenged them against the genome sequenced strain AP03 of A. astaci isolated from a North American red swamp crayfish, Procambarus clarkii Girard 1852, in the Garrotxa Natural Park, Girona. The results showed that there are significant differences (P<0,001) among populations, although most of them show high mortality rates after the zoospore challenge with A. astaci. However, one population from Girona exhibited a 100% survival during a four-month monitoring period under the experimental conditions tested. Histological analyses revealed a high immune reaction in tissues examined, i.e., encapsulation and melanization of hyphae, similar to that found in North American resistant crayfish species. These results represent the first observation of a native European crayfish population showing high resistance towards the most virulent genotype of this pathogen, i.e., genotype Pc. The identification of this population is of key importance for the management of these endangered species, and represents a crucial step forward towards the elucidation of the factors involved in the immune reaction against this devastating pathogen.

Invasive dreissenid mussels benefit invasive crayfish but not native crayfish in the Laurentian Great Lakes

Invasive ecosystem engineers, such as dreissenid mussels, may facilitate subsequent invaders. Despite their potential ecological importance, interactions between dreissenid mussels and crayfish in the Laurentian Great Lakes have received little research attention. Invasive rusty crayfish (Orconectes rusticus) have recently spread within the Great Lakes, and we hypothesized that food resources provided by invasive dreissenid mussels may have enhanced this spread. Dreissenid mussels may also benefit native crayfish such as the virile crayfish (O. virilis), but the distribution of virile species has not increased in the Great Lakes in recent years. We tested the interactive effects of dreissenid mussels and crayfish density on the growth, survival and activity of sympatric rusty and virile crayfish using a mesocosm experiment. We found that dreissenid mussels increased growth and activity of rusty crayfish while high crayfish densities negatively affected rusty crayfish growth. Dreissenid mussels did not affect growth or activity of virile crayfish, but high crayfish densities negatively affected their survival. The different responses of rusty and virile crayfish to mussels may be due to a greater ability of invasive crayfish to exploit mussel-associated food resources and/or to behavioral interactions between these species in sympatry. Our results suggest that dreissenid mussels may facilitate the establishment, spread, and potential impacts of invasive crayfish where these taxa co-occur.

Invasive red swamp crayfish (Procambarus clarkii) and native noble crayfish (Astacus astacus) similarly reduce oligochaetes, epipelic algae, and meiofauna biomass: a microcosm study

AbstractHuman activities have led to the decline of native crayfish and promoted dispersion of invasive species in European freshwater ecosystems. Crayfish are well-known predators of benthic macroinvertebrates, but benthic communities in aquatic ecosystems also include an abundant and functionally important meiofaunal component. For these organisms, the effects of invasive and native crayfish species are poorly understood. In this study, the effects of predation by the invasive red swamp crayfish (Procambarus clarkii) and the native noble crayfish (Astacus astacus) on the density, biomass, and secondary production of meiofaunal assemblages were compared in a model ecosystem experiment. Both crayfish species reduced the overall density of oligochaetes; the biomasses of total meiofauna, oligochaetes, and microcrustaceans; and secondary production by total meiofauna and oligochaetes. Nematodes and rotifers were unaffected by either crayfish species. An analysis of the gut contents of P. clarkii and A. astac...

The least known European native crayfish Astacus pachypus (Rathke, 1837) revealed its phylogenetic position

The thick-clawed crayfish Astacus pachypus (Rathke, 1837) is the least known species within the Astacidae, mostly due to limited access to samples and declining populations in recent decades. In the present study, for the first time, we report the phylogenetic position of this vulnerable native European freshwater crayfish within the genus Astacus, based on mitochondrial (COI and 16S rRNA) and nuclear (ITS2) molecular markers. Genetic results suggest its closest relationship is to A. leptodactylus (Eschscholtz, 1823), as previously suggested by morphology and common area of occurrence.

Molecular and morphometric characterisation of the invasive signal crayfish populations in Croatia

The signal crayfish Pacifastacus leniusculus (Dana, 1852) is a native species to North America. It was introduced to Europe and Japan where it rapidly spread as an invasive species. In Croatia, it is recorded in the rivers Mura and Drava, where it spread downstream from Slovenia, and in the Korana River, where it has been recently illegally introduced. In the invaded areas, signal crayfish outcompetes native crayfish species. Since the knowledge on the genetic diversity of this invasive species is limited, microsatellite markers and sequences of mitochondrial gene for 16S rRNA were analysed to explore the genetic relations between the two Croatian populations (Mura and Korana rivers) as well as their relation to other already studied European populations. Moreover, 16S rRNA sequence fragments of Croatian samples were compared with those from the native range in the west North America. Morphometric characteristics were also studied to determine if there are significant differences between studied populations and if these are concordant with the genetic analyses results. Also, morphometric data were used to assign Croatian signal crayfish into subspecies classification according to Miller’s discriminant function formula, and to compare claw surface area among Croatian, Japanese and North American populations. Based on the results of morphometric characteristics Croatian samples showed Pacifastacus leniusculus leniusculus -like morphology. Phylogenetic reconstruction based on 16S rRNA, positioned Croatian samples into P. leniusculus sensu Larson et al. (2012). Results on microsatellite markers showed that the genetic diversity of P. leniusculus in the Mura River population is slightly higher compared to the Korana River population, but these two populations do not form separated genetic clusters. This study contributes to the knowledge on genetic variability and morphometric characteristics of signal crayfish in Europe and further understanding of its success as an invasive species.

The prevalence of Aphanomyces astaci in invasive signal crayfish from the UK and implications for native crayfish conservation.

The crayfish plague agent, Aphanomyces astaci, has spread throughout Europe, causing a significant decline in native European crayfish. The introduction and dissemination of this pathogen is attributed to the spread of invasive North American crayfish, which can act as carriers for A. astaci. As native European crayfish often succumb to infection with A. astaci, determining the prevalence of this pathogen in non-native crayfish is vital to prioritize native crayfish populations for managed translocation. In the current study, 23 populations of invasive signal crayfish (Pacifastacus leniusculus) from the UK were tested for A. astaci presence using quantitative PCR. Altogether, 13 out of 23 (56·5%) populations were found to be infected, and pathogen prevalence within infected sites varied from 3 to 80%. Microsatellite pathogen genotyping revealed that at least one UK signal crayfish population was infected with the A. astaci genotype group B, known to include virulent strains. Based on recent crayfish distribution records and the average rate of signal crayfish population dispersal, we identified one native white-clawed crayfish (Austropotamobius pallipes) population predicted to come into contact with infected signal crayfish within 5 years. This population should be considered as a priority for translocation.

The occurrence of branchiobdellidans on stone crayfish (Austropotamobius torrentium) in the Czech Republic

The stone crayfish Austropotamobius torrentium (Schrank, 1803) is one of only two native crayfish species in the Czech Republic. Epibiotic branchiobdellidans present on this crayfish species have not been studied before in the Czech Republic. Here we evaluate the occurrence, and basic population characteristics of branchiobdellidans inhabiting A. torrentium in 12 small streams in the Czech Republic. Three Branchiobdella species were found: Branchiobdella parasita , and B. pentadonta dominated. B. hexadonta was found only exceptionally, as we did not focus on species inhabiting the gill chamber. The overall abundance varied between 0.3 and 17 individuals per crayfish. The mean length of B. parasita was 3.58 (1.1–7.1) mm, of B. pentadonta 2.00 (0.9–4.9) mm, and of B. hexadonta 1.73 (1.4–2.2) mm.

Risk assessment of pet-traded decapod crustaceans in the Republic of Kazakhstan, the leading country in Central Asia

The pet trade with decapod crustaceans has been considered one of the main pathway of introduction of these animals worldwide. As the leading markets in this regards are the Czech Republic, Germany and the USA. Central Asia is not perceived as an important market with ornamental decapod crustaceans. Despite this assumption, we found at least 16 species of freshwater shrimp, crayfish and crab species pet-traded in the Republic of Kazakhstan, the largest country in this region. Considering computed risk assessment, the origin of particular species, their availability on the market, the probability of establishment and further aspects, we identified two crayfish Procambarus clarkii and Procambarus fallax f. virginalis being the seriously hazardous taxa with high potential to threaten native crayfish species as well as inhabited ecosystems. To prevent their introductions and to minimize the risks of mentioned species, similarly as in the case of European Union, we recommend the total ban of import, trade and keeping of these high-risk taxa within Central Asia.

English

Abstract Invasive crayfish are known to displace native crayfish species, alter aquatic habitat and community structure and function, and are serious pests for fish hatcheries. White River Crawfish (WRC; Procambarus acutus) were inadvertently introduced to a warm-water fish hatchery in Missouri, USA, possibly in an incoming fish shipment. We evaluated the use of chemical control for crayfish to ensure incoming and outgoing fish shipments from hatcheries do not contain live crayfish. We conducted acute (≤ 24 hr) static toxicity tests to determine potency, dose-response, and selectivity of pesticides to WRC, Virile Crayfish (VC; Orconectes virilis), and Fathead Minnow (FHM; Pimephales promelas). Testing identified a formulation of cypermethrin (Cynoff®) as the most potent of five pesticides evaluated for toxicity to crayfish. A 4-hr exposure to a cypermethrin concentration of 100 μg·L-1 was found to kill 100% of juvenile and adult WRC; however, adult VC were not consistently killed. Concentrations of cypermethrin ≤ 100 μg·L-1 did not cause significant (&gt; 10%) mortality in juvenile FHM. Additional testing is needed to examine selectivity between crayfish and hatchery fish species. Biosecurity protocols at hatcheries that use chemical control have the potential to reliably prevent inadvertent transfers of live crayfish in fish shipments.

Native and alien crayfish species: do their trophic roles differ?

AbstractFreshwater crayfish are regarded as ecosystem engineers and keystone species. They act on various trophic levels and influence plant and animal species, community-level properties, and ecosystem processes. Comparisons of native and alien crayfish suggest greater negative effects of alien than native crayfish, but the species-specific roles of native and alien crayfish remain unclear. We used 2 enclosure experiments in streams to study biomass-related effects of the native Astacus astacus and Austropotamobius torrentium and the alien Pacifastacus leniusculus on available food types and the potential fate of these nutrients in the stream food web. In experiment 1, we compared the effects of crayfish (2 densities and a no-crayfish control) on leaf breakdown, production of leaf fragments, and accumulation of fine particulate matter (FPM). In experiment 2, we investigated predation by individual crayfish on Gammarus, Hydropsyche, and Arctic Char carrion. Pacifastacus leniusculus had stronger effects on...

Invasion-Related Change in Crayfish Density Affects a Stream Macroinvertebrate Community

Abstract Orconectes rusticus (Rusty Crayfish) have invaded streams of the upper Susquehanna River catchment, NY, replacing native crayfish and, in some areas, increasing overall crayfish density. Crayfish are important consumers and significant agents of disturbance in aquatic communities, so the introduction and expansion of Rusty Crayfish could affect the invaded community through the change in crayfish species composition, the increase in crayfish density, or some combination of the two. Other macroinvertebrates are prey of, competitors with, or subject to disturbance by crayfish and so are likely to be affected by changes in the crayfish assemblage. I conducted experiments in stream enclosures to determine the effects of crayfish species and density on the macroinvertebrate community. Increasing crayfish density reduced macroinvertebrate density but did not significantly affect macroinvertebrate taxon richness, diversity, or community composition. At moderate densities, the effects of native O. propin...

Distribution of crayfish species in Hungarian waters

Three native crayfish species, i.e. Astacus astacus, Astacus leptodactylus and Austropotamobius torrentium, occur in Hungary. Lately, however, non-indigenous crustaceans have also invaded the country Their most recent distribution and impact on the occurrences of the native species is not clear. Consequently, the first object of the present study was to investigate the present-day distribution and habitat preference of the native and invasive crayfish and crab species in Hungary according to water types and surface water velocity values. The second aim was to investigate the changes in the distribution patterns of all species over the last 20 years and to identify potential risks for native species in Hungary. Although A. astacus was discovered on several new locations the overall distribution of the species is decreasing. The rarest crayfish is A. torrentium which was found only at three locations, making this the most endangered crayfish in Hungary. Although A leptodactylus used to occur especially in the main branches of the Danube and Tisza Rivers it shifted towards its tributaries after O. limosus appeared here. Despite their overlapping habitat preference and the fact that O. limosus is a carrier of the lethal crayfish plague, both species still co-occur at a few locations in Hungary Pacifastacus leniusculus is invading the country from the West and although it is not present in large numbers yet, it has replaced the local A. astacus populations and may further impact its distribution when it further increases its range in the future. Although occurrences of the Chinese mitten crab (Eriocheir sinensis) the marbled crayfish (Procambarus fallax f. virginalis) and the red swamp crayfish (Procambarus clarkii) have been reported in the literature, these species were not encountered during the survey Thus indicating that their occurrence in Hungary is not widespread yet. The increasing distribution of the invaders forms a constant threat to native crayfish populations in Hungary To ensure the survival of the native species it is important to keep track of the ongoing changes in crayfish distributions. Nevertheless, additional protection measures will be required to safe-guard the survival of the native crayfish populations in Hungary.

Habitat Assessment and Range Updates for Two Rare Arkansas Burrowing Crayfishes:Fallicambarus harpiandProcambarus reimeri

Abstract The Ouachita Highlands Freshwater Ecoregion harbors the 6th-highest native crayfish species density in the US and Canada. Many of these species are understudied, and the burrowing crayfishes of this region are of particular interest. We conducted field surveys in the spring of 2014 and 2015 to assess the range and habitat preferences of 2 of Arkansas' rarest burrowing crayfishes: Fallicambarus harpi (Ouachita Burrowing Crayfish) and Procambarus reimeri (Irons Fork Burrowing Crayfish). Both crayfishes are currently of conservation concern—F. harpi is vulnerable and P. reimeri is endangered according to the American Fisheries Society. Our surveys detected new populations of both species and documented marginal and wider range expansions for F. harpi and P. reimeri, respectively. The preferred habitat for both species was characterized as wet seepage areas with an open canopy, low grasses, and abundant sedges. Our surveys support prior observations that these species are geographically constrained; ...

First detection of the crayfish plague pathogen Aphanomyces astaci in South America: a high potential risk to native crayfish

The crayfish plague pathogen, Aphanomyces astaci, is a fungal-like organism (Oomycetes), specialized in parasitizing freshwater crayfish species. Crayfish plague is a disease that has caused losses of indigenous crayfish populations, especially in Europe. The pathogen chronically infects North American endemic crayfish, such as Procambarus clarkii, which is considered an invasive species in several continents, including South America. Using molecular tools, quantitative PCR, and conventional PCR, we detected this pathogen in feral P. clarkii populations established in southeastern Brazil. This is an alarming result because in South America, especially in Brazil, there is considerable endemic crayfish species diversity, especially in the genus Parastacus. Possible contacts between P. clarkii and the endemic crayfish could be seen as a major threat to the native crayfish, mainly because of the possibility of A. astaci transmission. Furthermore, our results indicate preliminary evidence of possible A. astaci infection, agent level A2, in two sympatric native species, namely Parastacus defossus and Parastacus pilimanus. In this study, we provide the first overview concerning the presence of the crayfish plague pathogen, A. astaci, in South America.

Trapping Aliens: Understanding the Complexities of Controlling Introduced Freshwater Crayfish in the United Kingdom

Abstract Invasive non-native species pose practical and ethical problems for the people tasked with their management. Invasive freshwater crayfish species in the UK threaten rare native crayfish and freshwater habitats, yet their control is beset with social, practical and environmental barriers to success. This paper draws on an interdisciplinary study of stakeholders involved in crayfish management in East Anglia to explore the management of non-native freshwater crayfish in the UK. It concludes that when standard methods of control fail, stakeholders are willing to consider unusual management suggestions such as commercial trapping, whilst recognising that these may bring their own problems.