Crayfish Research Articles

Morphological and molecular characters of Cherax quadricarinatus (von Martens, 1868) from Sermo Reservoir and Tambakboyo Retention Basin, Daerah Istimewa Yogyakarta, Indonesia

The Australian red claw freshwater crayfish, Cherax quadricarinatus is one of the most widely distributed and cultivated freshwater crayfish due to its high tolerance towards various environmental conditions. Native to North Australia and South Papua New Guinea, this crayfish was found in Tambakboyo Retention Basin in 2016 and Sermo Reservoir in 2019. This research was aimed to identify the morphological and molecular characters of C. quadricarinatus collected from Sermo Reservoir and Tambakboyo Retention Basin, Yogyakarta. The genetic information of the samples was compared to Australian red claw freshwater crayfish currently available. The methodology used for this research are morphological, morphometrical, meristic identification, and molecular identification using the PCR method. The primer used to be 1471 primers as the forward primer and 1472 primers as the reverse primer. In conclusion, all six specimens obtained were identified to be C. quadricarinatus. Morphological analysis using UPGMA showed that all specimens were formed one big cluster and has the highest similarity index (1.00). Molecular analysis using BLAST showed that specimen from Sermo Reservoir was 98.96% identical to C. quadricarinatus and specimen from Tambakboyo Retention Basin was 100% identical to C. quadricarinatus. Thus concluding that based on their morphological and molecular character, all samples of this study were C. quadricarinatus. This finding also contributes to the distribution information of C. quadricarinatus in Daerah Istimewa Yogyakarta

ГЕМАТОЛОГИЧЕСКИЕ И БИОХИМИЧЕСКИЕ ПОКАЗАТЕЛИ ГЕМОЛИМФЫ АВСТРАЛИЙСКОГО КРАСНОКЛЕШНЕВОГО РАКА

The article describes Australian red claw crayfish, Cherax quadricarinatus, which is currently one of the most promising cultivation targets. However, to increase production volumes, it is necessary to improve cultivation technologies, which should be based on the data of physiological and biochemical parameters. An objective method for monitoring the physiological state 
 of Australian red claw crayfish in the artificial conditions is determining its hematological and biochemical indicators that complement the general characteristics of hemolymph and later define its physiological norm. When giving the objects the compound feed, which the authors produced by their own recipe, there was recorded a high level of total hemolymph protein of 40.8 ± 4.5 g/l. According to the results of biochemical research, the cholesterol content in the hemolymph of Australian crayfish was 3.2 ± 0.6 mmol/l, and the concentration of lipoproteins was 0.8 ± 0.2 g/l (levels within the reference values). When considering the hemogram of hemolymph there were found the dominant types and linear dimensions of native formed elements. The diameter of agranulocytes in Australian freshwater crayfish varied from 85 to 90 μm, semi-granulocytes - from 90 to 95 μm, granulocytes - from 65 to 78 μm, transparent cells differed by greater variability in size, which ranged from 85 to 120 μm. The part of granulocytes in relation to other shaped elements exceeded 50%, for transparent cells it turned out to be above 20%, for semi-granulocytes - about 15% and for agranulocytes - about 5%, which means that the latter form the rarest group. The established ratios are specific for Cherax quadricarinatus, its hemocytic characteristics greatly differs from Astacus leptodactylus, which is the main object of comparative research. The results of comparative analysis of the cellular composition of the hemolymph of the Australian freshwater crayfish Cherax quadricarinatus (Von Martens, 1868) demonstrate the taxonomic specificity of this representative of freshwater aquaculture

Studying the Drying Kinetics of Fresh-water Crayfish (Austropotamobius pallipes) on Thin-layers

Studying the Drying Kinetics of Fresh-water Crayfish (Austropotamobius pallipes) on Thin-layers

Heavy Metals in the Muscle and Hepatopancreas of Red Swamp Crayfish (Procambarus clarkii) in Campania (Italy).

Simple SummaryHeavy metals can represent a serious threat to marine and freshwater fauna through exposure, bioaccumulation and biomagnification processes. The aim of this study was to evaluate the presence of non-essential and essential elements in freshwater crayfish (Procambarus clarkii) edible tissues to establish the healthiness of this product and to evaluate the pollution status of the sampling sites from Campania region (Italy). The results suggest that crayfish were safe for human consumption and indicated mild contamination of heavy metals of the sampling areas. The aim of this study was to carry out a quali-quantitative analysis of the presence of non-essential and essential trace elements in freshwater crayfish (Procambarus clarkii) edible tissues to establish the healthiness of this product and to evaluate the pollution status of the sampling sites included in the present study. P. clarkii is one of the most common species of freshwater crustaceans in Italy, regularly consumed by local people. Moreover, the crayfish, due to its trophic position and diet, can be considered as an excellent bioindicator of the health status of the ecosystem. We collected sixty crayfish samples from two different sites in Campania (Italy): Villa Literno and Sessa Aurunca. Concentrations of trace elements were determined by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Our data showed low concentrations of Cd, Hg and Pb, with values below the European Commission MRL (Commission Regulation (EC) 1881/2006). We suggest that data obtained from this study showed that crayfish collected from Villa Literno and Sessa Aurunca were safe for human consumption. Furthermore, the results of this research indicated mild contamination of heavy metals of the sampling sites, indicating a good health status of the area’s aquatic ecosystem.

Biological insights into the rapid tissue regeneration of freshwater crayfish and crustaceans.

The freshwater crayfish is capable of regenerating limbs, following autotomy, injury and predation. In arthropod species, regeneration and moulting are two processes linked and strongly regulated by ecdysone. The regeneration of crayfish limbs is divided into wound healing, blastema formation, cellular reprogramming and tissue patterning. Limb blastema cells undergo proliferation, dedifferentiation and redifferentiation. A limb bud, containing folded segments of the regenerating limb, is encased within a cuticular sheath. The functional limb regenerates, in proecdysis, in two to three consecutive moults. Rapid tissue growth is regulated by hormones, limb nerves and local cells. The TGF-β/activin signalling pathway has been determined in the crayfish, P. fallax f. virginalis, and is suggested as a potential regulator of tissue regeneration. In this review article, we discuss current understanding of tissue regeneration in the crayfish and various crustaceans. A thorough understanding of the cellular, genetic and molecular pathways of these biological processes is promising for the development of therapeutic applications for a wide array of diseases in regenerative medicine.

Early Changes in Crayfish Hemocyte Proteins after Injection with a β-1,3-glucan, Compared to Saline Injected and Naive Animals.

Early changes in hemocyte proteins in freshwater crayfish Pacifastacus leniusculus, in response to an injection with the fungal pattern recognition protein β-1,3-glucan (laminarin) were investigated, as well as changes after saline (vehicle) injection and in naïve animals. Injection of saline resulted in rapid recruitment of granular hemocytes from surrounding tissues, whereas laminarin injection on the other hand induced an initial dramatic drop of hemocytes. At six hours after injection, the hemocyte populations therefore were of different composition. The results show that mature granular hemocytes increase in number after saline injection as indicated by the high abundance of proteins present in granular cell vesicles, such as a vitelline membrane outer layer protein 1 homolog, mannose-binding lectin, masquerade, crustin 1 and serine protease homolog 1. After injection with the β-1,3-glucan, only three proteins were enhanced in expression, in comparison with saline-injected animals and uninjected controls. All of them may be associated with immune responses, such as a new and previously undescribed Kazal proteinase inhibitor. One interesting observation was that the clotting protein was increased dramatically in most of the animals injected with laminarin. The number of significantly affected proteins was very few after a laminarin injection when compared to uninjected and saline-injected crayfish. This finding may demonstrate some problematic issues with gene and protein expression studies from other crustaceans receiving injections with pathogens or pattern recognition proteins. If no uninjected controls are included and no information about hemocyte count (total or differential) is given, expressions data for proteins or mRNAs are very difficult to properly interpret.

Diversity, Distribution and Habitat Use of Freshwater Crayfish in the Upper Appomattox River Basin, Virginia

The Appomattox River basin in Virginia is a poorly understood system for freshwater crayfish diversity and distribution. We sampled 36 locations in the upper Appomattox basin for crayfish and noted general habitat characteristics. The following 7 species of crayfish were discovered in the system belonging to 4 genera: Cambarus cf. acuminatus, Cambarus bartonii bartonii (Common Crayfish), Cambarus longulus (Atlantic Slope Crayfish), Lacunicambarus diogenes (Devil Crayfish), Procambarus acutus (White River Crayfish), Creaserinus fodiens (Digger Crayfish), and invasive Procambarus clarkii (Red Swamp Crayfish). Native C.cf. acuminatus dominates the upper Appomattox region, having a wider distribution and higher relative abundance compared to other species in the basin. All other taxa demonstrated relatively limited distributions and low abundance. The least encountered species were the 2 primary burrowing species, Devil Crayfish and Digger Crayfish, which exclusively used shallow seasonal pools during the spring breeding season. We report range extensions for C. cf. acuminatus, Atlantic Slope Crayfish, Common Crayfish, Devil Crayfish, Digger Crayfish, and Red Swamp Crayfish, and recommend additional surveys to improve our understanding of the diversity and distribution of crayfish in the Appomattox River basin. Furthermore, we recommend monitoring of the Briery Creek and Sandy River systems to assess the extent and severity of the Red Swamp Crayfish invasion. Additionally, we urge a systematic study to resolve the taxonomic uncertainty of a potentially new Creaserinus species in the Appomattox River basin.

Astacus multicavatus Bell, 1863 is a marine lobster (Decapoda: Erymoidea: Erymidae), not a freshwater crayfish

Abstract Crayfishes comprise a large and diverse group of freshwater lobster-like crustaceans. Despite being abundant in the recent, they are extremely rare in the fossil record. We revise a putative occurrence of Astacus multicavatusBell, 1863 from the marine Hauterivian of Speeton Clay (Speeton, United Kingdom), which was used a few years ago as a calibration fossil representing AstacusFabricius, 1775 for divergence time analyses. This species is actually a senior synonym to Eryma sulcatumHarbort, 1905. It so appears that Eryma multicavatum (Bell, 1863) comb. nov. is not a freshwater crayfish but a marine representative of Erymidae. Two co-occurring isolated chelae, also from the Speeton Clay, may correspond to larger, older specimens of E. multicavatum comb. nov.

Human health risk assessment of selected metal(loid)s via crayfish (Faxonius virilis; Procambarus acutus acutus) consumption in Missouri

Farmed crustaceans are an important component in addressing the rising animal protein demand. The present study determined the concentrations of fourteen elements (Ag, As, Be, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Sn, Pb, and Zn) in the edible abdominal muscle of cultured freshwater crayfish species (Faxonius virilis; Procambarus acutus acutus) from Missouri. Also, this paper describes the dietary intake and the human health risks from the consumption of crayfish muscle in the adult population. Overall, 172 animals were captured between February 2017 and January 2018 for assessment. Concentrations of metals (Ag, Be, Cd, Cu, Co, Cr, Fe, Mn, Ni, Pb, Sn, Mo, and Zn) and metalloid (As) in the muscle tissue were determined after microwave-assisted acid digestion by ICP - OES. Health indices (EDI/EWI: estimated daily/weekly intakes; THQ: target hazard quotient; TTHQ: total target hazard quotient; ILCR: incremental lifetime cancer risk; and ∑ILCR: cumulative lifetime cancer risk) were calculated and compared to thresholds. Of all samples, the highest concentrations (mg kg −1 wet weight) of metal(loid)s in muscle were Ag (0.11), As (3.15), Be (0.21), Cd (0.11), Co (0.32), Cr (1.22), Cu (107), Fe (23.0), Mn (8.54), Mo (0.62), Ni (2.65), Pb (1.76), Sn (5.91), and Zn (19.2). In both species, the average As, Cd, and Zn concentrations were below the legal limits. However, the levels of Cu, Pb, and As, in some samples, were in exceedance of the maximum levels. In both species, a significant correlation (p < 0.05) was observed between the carapace length (CL) and animal body weight (BW). In P. acutus, CL, BW, and animal total length were homogenous (p > 0.05) among the sexes. Non-parametric Kruskal–Wallis test results indicated significant differences (p < 0.05) in the levels of As, Be, and Zn in F. virilis, and Be and Cr in P. a. acutus among the genders. Significant inter-species differences (p < 0.05) were observed in the levels of Be, Ni, and Pb and the growth factors. The EDI/EWI values were below the permissible limits. THQ and TTHQ values, being below 1.0, indicated no probabilistic health risk. Regarding carcinogenic risk, only As and Ni indicated cancer risk (ILCR >10−5 and ∑ILCR >10−5) to the adult population. High metals/metalloid exposure from crayfish muscle consumption posed potential health hazards to the adult population.

The features of an emerging whispovirus isolate from freshwater crayfish

A highly lethal freshwater crayfish Cambarus clarkii whispovirus (WSSV-Cc) was isolated from a naturally infected host. A large number of viral particles with typical nimavirus characters were observed in host cells. Genomic architecture and genetic evolution of this extremely virulent pathogen were uncovered. WSSV-Cc has a double-stranded DNA genome containing 287,179 bp, encoding 180 putative ORFs. Congruence analysis was performed between WSSV-Cc and known nimavirus genomes. The genome of WSSV-Cc is smaller than that found in isolates sampled before 2010, but is similar in size to that of recent isolates, which provided new evidence for the shrinkage of nimavirus genome size during evolution. Phylogenetic analysis with the complete genome also showed connections between genome size and evolutionary relationship. Twenty low-similarity genes and three variable regions were identified from the WSSV-Cc genome. In addition, two recombination events were detected in the WSSV-Cc genome, and analysis of the recombinant regions showed a close relationship among the three freshwater crayfish nimaviruses. These findings provide us the morphological, genomic, and genetic characters of an emerging whispovirus, which will broaden our understanding to nimaviruses and be useful for diagnosis of crayfish viral disease.

Short communication: Production, distribution and conservation analysis of Cherax crayfish endemic to Papua and West Papua Provinces, Indonesia

Abstract. Widyasari F, Sayuti M, Salampessy RBS. 2021. Short communication: Production, distribution and conservation analysis of Cherax crayfish endemic to Papua and West Papua Provinces, Indonesia. Biodiversitas 22: 3271-3276. Freshwater crayfish is a species from the Parastacidae family that is indigenous to Papua and West Papua Indonesia. This study analyzes the amount of production, economic value, distribution, and conservation of freshwater crayfish endemic to Papua and West Papua. The production data were obtained from Stasiun Karantina Ikan or Fish Quarantine Inspection Agency in Papua and West Papua, Indonesia. Data regarding the price of Cherax crayfish were determined based on interviews with freshwater crayfish sellers. Furthermore, the distribution of freshwater crayfish was explained based on a literature review, while the data of its conservation were retrieved from the IUCN Red List of Threatened Species. Cherax crayfish caught from wild populations in West Papua is known higher than in Papua. Increased sales revenue could support the economy of the local community. There have been 25 species of freshwater crayfish identified, nine of which were from West Papua and 16 from Papua. Three species were under Endangered (EN), Least Concern (LC), Vulnerable (VU) status, respectively. Four species were under Data Deficient (DD) status, while the rest were unidentified. Overfishing of Cherax crayfish causes decline Cherax crayfish stock in the wild, future researchers are expected to conduct more specific studies that include relevant stakeholders regarding the conservation of Cherax crayfish that are endemic to Papua and West Papua.

A new insight to characterize immunomodulation based on hepatopancreatic transcriptome and humoral immune factor analysis of the Cherax quadricarinatus infected with Aeromonas veronii

Cherax quadricarinatus is a type of large freshwater crayfish that is characterized by rapid growth and formidable adaptability. It has also been widely cultured and studied as a model organism. Aeromonas veronii is the dominant pathogen in aquatic environments and the primary threat to aquaculture’s economic stability. To better understand the interactions between C. quadricarinatus and A. veronii, high-throughput RNA sequencing of the C. quadricarinatus hepatopancreas was carried out on a control group, susceptible group (6 h after infection), and resistant group (48 h after infection). A total of 65,850,929 genes were obtained. Compared with the control group, 2616 genes were up-regulated and 1551 genes were down-regulated in the susceptible group; while 1488 genes were up-regulated and 1712 genes were down-regulated in the resistant group. GO and KEGG analysis showed that these differentially expressed genes (DEGs) were associated with multiple immune pathways, including Toll-like receptors (TLRs), antigen processing and presentation, NOD-like receptor signaling pathway, phagosome, lysosome, JAK-STAT signaling pathway. qRT-PCR showed that infection by A. veronii changed the expression pattern of the serine proteinase inhibitor (SPI), crustacean hyperglycemic hormone (CHH), anti-lipopolysaccharide factor (ALF), and extracellular copper/zinc superoxide dismutase (SOD1), all of which were significantly higher than in the control group up to 48 h after infection. In addition, detection of superoxide dismutase (SOD), catalase (CAT), lysozyme (LZM), and phenoloxidase (PO) activity, as well as ceruloplasmin (CP) concentration at different times after infection showed diverse trends. Furthermore, pathological sections obtained 24 h after infection show lesions on the hepatopancreas and intestinal tissues caused by A. veronii. The results of this study provide a foundation for analyzing the immune mechanism of C. quadricarinatus infected with A. veronii at the transcriptional level and a theoretical basis for screening disease-resistant individuals to ensure healthy economic development of the aquatic industry.

A Comprehensive Review on Crustaceans' Immune System With a Focus on Freshwater Crayfish in Relation to Crayfish Plague Disease.

Freshwater crayfish immunity has received great attention due to the need for urgent conservation. This concern has increased the understanding of the cellular and humoral defense systems, although the regulatory mechanisms involved in these processes need updating. There are, however, aspects of the immune response that require clarification and integration. The particular issues addressed in this review include an overall description of the oomycete Aphanomyces astaci, the causative agent of the pandemic plague disease, which affects freshwater crayfish, and an overview of crustaceans’ immunity with a focus on freshwater crayfish. It includes a classification system of hemocyte sub-types, the molecular factors involved in hematopoiesis and the differential role of the hemocyte subpopulations in cell-mediated responses, including hemocyte infiltration, inflammation, encapsulation and the link with the extracellular trap cell death pathway (ETosis). In addition, other topics discussed include the identity and functions of hyaline cells, the generation of neoplasia, and the emerging topic of the role of sessile hemocytes in peripheral immunity. Finally, attention is paid to the molecular execution of the immune response, from recognition by the pattern recognition receptors (PRRs), the role of the signaling network in propagating and maintaining the immune signals, to the effector elements such as the putative function of the Down syndrome adhesion molecules (Dscam) in innate immune memory.

Survival, Growth, and Reproduction: Comparison of Marbled Crayfish with Four Prominent Crayfish Invaders.

Simple SummaryBiological invasions exert tremendous impacts on native biodiversity and ecosystem functioning. Invasive crayfish species are well known for their particularly vigorous impacts. Recent research indicated that locations with multiple invasive crayfish species are increasing, yet questions asking which species and under what circumstances will dominate have remained unanswered. Conducting a set of independent trials of single-species stocks (intraspecific interactions) and mixed stocks (interspecific interactions) of marbled crayfish in combination with other four crayfish species invasive to Europe we evaluated survival, growth, claw injury, and reproduction. In both single and mixed stocks, red swamp crayfish and common yabby grew faster than marbled crayfish, while marbled crayfish were superior to both spiny-cheek and signal crayfish in terms of growth. Except for the trial with signal crayfish, the faster-growing species consistently reached a higher survival rate. Thus, the success of the marbled crayfish is significantly driven by its relatively fast growth as well as early and frequent reproduction. Our results indicate how interactions between invasive populations can unfold in the future and underline the complex population dynamics between existing and emerging invasive species.Biological invasions are increasingly recognized ecological and economic threats to biodiversity and are projected to increase in the future. Introduced freshwater crayfish in particular are protruding invaders, exerting tremendous impacts on native biodiversity and ecosystem functioning, as exemplified by the North American spiny-cheek, signal and red swamp crayfish as well as the Australian common yabby. The marbled crayfish is among the most outstanding freshwater crayfish invaders due to its parthenogenetic reproduction combined with early maturation and high fecundity. As their introduced ranges expand, their sympatric populations become more frequent. The question of which species and under what circumstances will dominate in their introduced communities is of great interest to biodiversity conservation as it can offer valuable insights for understanding and prioritization of management efforts. In order to examine which of the aforementioned species may be more successful as an invader, we conducted a set of independent trials evaluating survival, growth, claw injury, and reproduction using single-species stocks (intraspecific interactions) and mixed stocks (interspecific interactions) of marbled crayfish vs. other crayfish invaders since the onset of exogenous feeding. In both single and mixed stocks, red swamp crayfish and yabby grew faster than marbled crayfish, while marbled crayfish were superior to both spiny-cheek and signal crayfish in terms of growth. With the exception of signal crayfish, the faster-growing species consistently reached a higher survival rate. The faster-growing species tended to negatively impair smaller counterparts by greater claw injury, delayed maturation, and reduced fecundity. Only marbled crayfish laid eggs as early as 14 weeks in this study, which is earlier than previously reported in the literature. Thus, the success of marbled crayfish among invasive crayfish is significantly driven by relatively fast growth as well as an early and frequent reproduction. These results shed light on how interactions between invasive populations can unfold when their expansion ranges overlap in the wild, thereby contributing to the knowledge base on the complex population dynamics between existing and emerging invasive species.

Environmental DNA detection of the giant freshwater crayfish (Astacopsis gouldi)

AbstractThe giant freshwater crayfish, Astacopsis gouldi Clark, 1936, is an endangered endemic freshwater species native to Northern Tasmania. Habitat loss, fishing pressure, and climate change have been identified as threatening processes. The Australian government approved a recovery plan for A. gouldi in 2017 that requires routine population surveys to assess the impact of ongoing threats and recovery actions. We developed a novel species‐specific probe‐based assay targeting a 219 bp fragment in the Cytochrome Oxidase 1 gene region to detect traces of A. gouldi DNA in environmental samples as a cost‐effective, sensitive, and non‐invasive surveillance method to assess the presence of this endangered species. We tested assay specificity against ten crayfish species commonly found in Tasmania within the Astacopsis, Cherax, Geocharax, Engaeus, and Ombrastacoides genera and determined assay sensitivity using tissue‐derived genomic DNA and synthetic oligo standards designed for A. gouldi. We then tested water samples collected from aquaria and natural freshwater streams in Northern Tasmania with known occurrence of A. gouldi, as well as one site with no known A. gouldi occurrence. The probe‐based assay designed in this study successfully detected A. gouldi DNA and eDNA with a 10 copies/µl limit of detection and showed no amplification of non‐targeted co‐existing crayfish species. We successfully detected the presence of A. gouldi eDNA in water samples from six sites with known occurrences of the species. There was no detection from the negative site. This study validates the use of eDNA‐based detection of A. gouldi by real‐time PCR as a non‐invasive monitoring tool to assist field monitoring, assessment, and complement ongoing recovery actions to protect habitable ecosystems of A. gouldi.

Aerobic and anaerobic metabolic scaling in the burrowing freshwater crayfish Parastacus pugnax.

Metabolic scaling is a well-known biological pattern. Theoretical scaling exponents near 0.67 and 0.75 are the most widely accepted for aerobic metabolism, but little is known about the scaling of anaerobic metabolism. Furthermore, metabolic scaling has been mainly evaluated in organisms primarily relying on aerobic pathways. Here we evaluate both aerobic and anaerobic metabolic scaling in Parastacus pugnax, a burrowing freshwater crayfish endemic to Chile, which inhabits waters with low pO2 (~ 1mg O2 L-1, measured in this study). We determined the metabolic rate, total oxidative capacity (Electron Transport System: ETS), critical oxygen tension (Pcrit) and muscular Lactate dehydrogenase (LHD) and Malate dehydrogenase (MDH) enzymatic activities (proxies of anaerobic metabolism) over a wide range of P. pugnax sizes (0.24-42.93g wet mass). Aerobic metabolism scaled with crayfish size with an exponent of 0.78, remarkably similar to the 0.73 which scaled the ETS, the enzymatic complex behind respiration. Critical partial pressure of oxygen (Pcrit) was calculated as 15.6 ± 2.9mmHg, showing that aerobic metabolism was efficiently maintained until ~ 10% air saturation. Below this threshold, P. pugnax switched to anaerobic metabolism, evidenced by a reduction in aerobic metabolism and ETS activity under chronic low oxygen conditions. None of the activities of MDH, LDH, their ratio (MDH/LDH), nor Pcrit scaled with crayfish size, indicating that these animals are equally adapted to hypoxic environments throughout their whole ontogeny. Given the particularities of its habitat, the information presented here is valuable for a proper management and successful conservation.

Tracing the origin of the crayfish plague pathogen, Aphanomyces astaci, to the Southeastern United States

The oomycete Aphanomyces astaci is an emerging infectious pathogen affecting freshwater crayfish worldwide and is responsible for one of the most severe wildlife pandemics ever reported. The pathogen has caused mass mortalities of freshwater crayfish species in Europe and Asia, and threatens other susceptible species in Madagascar, Oceania and South America. The pathogen naturally coexists with some North American crayfish species that are its chronic carriers. Presumptions that A. astaci originated in North America are based on disease outbreaks that followed translocations of North American crayfish and on the identification of the pathogen mainly in Europe. We studied A. astaci in the southeastern US, a center of freshwater crayfish diversity. In order to decipher the origin of the pathogen, we investigated (1) the distribution and haplotype diversity of A. astaci, and (2) whether there are crayfish species-specificities and/or geographical restrictions for A. astaci haplotypes. A total of 132 individuals, corresponding to 19 crayfish species and one shrimp species from 23 locations, tested positive for A. astaci. Mitochondrial rnnS and rnnL sequences indicated that A. astaci from the southeastern US exhibited the highest genetic diversity so far described for the pathogen (eight haplotypes, six of which we newly describe). Our findings that A. astaci is widely distributed and genetically diverse in the region supports the hypothesis that the pathogen originated in the southeastern US. In contrast to previous assumptions, however, the pathogen exhibited no clear species-specificity or geographical patterns.

More from less: Genome skimming for nuclear markers for animal phylogenomics, a case study using decapod crustaceans

AbstractLow coverage genome sequencing is rapid and cost-effective for recovering complete mitochondrial genomes for crustacean phylogenomics. The recovery of high-copy-number nuclear genes, including histone H3, 18S and 28S ribosomal RNAs, is also possible using this approach based on our research with freshwater crayfishes (Astacidea). We explored the potential of genome skimming (GS) to recover additional nuclear genes from shallow sequencing projects using decapod crustaceans. Using an in silico-baited approach, we recovered three additional core histone genes (H2A, H2B, and H4) from our low-coverage decapod dataset (99 species, 69 genera, 38 families, 10 infraorders). Phylogenetic analyses using various combinations of mitochondrial and nuclear genes for the entire decapod dataset and a subset of 40 species of crayfishes showed that the evolutionary rates for different classes of genes varied widely. A very high level of congruence was nevertheless found between trees from the six nuclear genes and those derived from the mitogenome sequences for freshwater crayfish. These findings indicate that nuclear genes recovered from the same genome skimming datasets designed to obtain mitogenomes can be used to support more robust and comprehensive phylogenetic analyses. Further, a search for additional intron-less nuclear genes identified several high-copy-number genes across the decapod dataset, and recovery of NaK, PEPCK, and GAPDH gene fragments is possible at slightly elevated coverage, suggesting the potential and utility of GS in recovering even more nuclear genetic information for phylogenetic studies from these inexpensive and increasingly abundant datasets.

Evolving in islands of mud: old and structured hidden diversity in an endemic freshwater crayfish from the Chilean hotspot

Parastacus is a genus of South American freshwater crayfishes disjunctively distributed in southern Chile, Northern Argentina, Uruguay and Southeastern Brazil. Parastacus pugnax is a Chilean endemic distributed along 700 km of latitude in central-southern Chile from the Pacific coast to the Andean piedmont, which is intensively captured for consumption for local communities. Considering the habitat (wet meadows) and natural history (primary burrower, non-migrant) of the species, we tested a hypothesis of highly structured genetic diversity using mtDNA of 465 specimens gathered at 56 localities across the species range. The crown age of P. pugnax was estimated at 38 Ma, predating the main Andean uplift. The genetic variation of P. pugnax is large and geographically structured. In some cases, genetic groups do not match basin limits, suggesting a previous to current dynamic of basin evolution. The uncovered intraspecific main lineages have different demographic histories. A latitudinal cline in past effective population size reduction suggests environmental singularities with a glacial effect in the southern populations. We suggest adding morphologic and more genetic data in order to assess species limits. Our results contribute to improve future conservation actions for this taxon, providing basic information to delimit conservation units.

Detecting Sex-Related Changes to the Metabolome of a Critically Endangered Freshwater Crayfish During the Mating Season.

Captive breeding is a vital tool in the conservation of highly endangered species, as it is for the Margaret River hairy marron, Cherax tenuimanus, from the south west of Australia. A close relative, Cherax cainii, has almost completely displaced C. tenuimanus in the wild and is a successful aquaculture species, whereas C. tenuimanus has performed poorly in captivity. We used untargeted liquid chromatography-mass spectrometry to obtain metabolomic profiles of female and male C. tenuimanus held in controlled aquarium conditions during their reproductive period. Using repeated haemolymph sampling we tracked the metabolomic profiles of animals just prior to and for a period of up to 34 days after pairing with a similar sized potential mate. We identified 54 reproducible annotated metabolites including amino acids, fatty acids, biogenic amines, purine and pyrimidine metabolites and excretion metabolites. Hierarchical clustering analysis distinguished five metabolite clusters. Principal component-canonical variate analysis clearly distinguished females from males, both unpaired and paired; similar trends in profile changes in both sexes after pairing; and a striking shift in males upon pairing. We discuss three main patterns of metabolomic responses: differentiation between sexes; reactive responses to the disturbance of pairing; and convergent response to the disturbance of pairing for males. Females generally had higher concentrations of metabolites involved in metabolic rate, mobilisation of energy stores and stress. Responses to the disturbance of pairing were also related to elevated stress. Females were mobilising lipid stores to deposit yolk, whereas males had a rapid and strong response to pairing, with shifts in metabolites associated with gonad development and communication, indicating males could complete reproductive readiness only once paired with a female. The metabolomic profiles support a previously proposed potential mechanism for displacement of C. tenuimanus by C. cainii in the wild and identify several biomarkers for testing hypotheses regarding reproductive success using targeted metabolomics.