Crayfish Tissues Research Articles

Impact of polyaluminum chloride on the bioaccumulation of selected elements in the tissues of invasive spiny-cheek crayfish (Faxonius limosus) – Potential risks to consumers

The effect of coagulants used in lake reclamation on crayfish is poorly understood. Therefore, the aim of this study was to evaluate changes in the bioaccumulation of Al, Ca, Cu, Fe, K, Mg, Na and Zn in the gills, exoskeleton, muscle and hepatopancreas of spiny-cheek crayfish (Faxonius limosus) as a result of exposure to PAX®18 coagulant, containing polyaluminum chloride. The study also evaluated the risk to human health from the consumption of crayfish muscle. Metal levels, determined using atomic absorption spectrometry, differed between metals (the highest concentrations for Ca, K, Na, Mg) and the body part. Calcium was most abundant in the exoskeleton, K in the muscles, while Cu and Al in the hepatopancreas. The bioaccumulation of metals was affected by exposure to the coagulant, with a statistically significant (p < 0.05) increase in muscle concentration of Al and Na and a decrease in Ca and Fe. The concentrations of elements (in μg g−1) in the muscle of the control group crayfish and those in contact with the coagulant were, respectively: K (2150; 2090), Na (1540; 2020), Ca (749; 602), Mg (207; 174), Al (103; 164), Zn (21.1; 19.1), Fe (7.6; 3.8) and Cu (8.4; 7.6). Most elements were below 12% of the Dietary Reference Values (DRV). The Al concentration in the muscle exceeded the tolerable weekly intake (TWI) (maximum 164% TWI for muscle of crayfish exposed to polyaluminum chloride). In conclusion, the studied F. limosus had typical elemental bioaccumulation for a crayfish, but the contact with the coagulant increased Al concentration and decreased Fe, Ca, Mg, Zn and Cu concentrations. The muscle of crayfish can be used as a supplementary source of essential elements in the human diet, but it seems necessary to introduce obligatory control of Al levels due to the use of polyaluminum chloride in lake restoration.

Dietary fatty acid profiles shape crayfish biosynthesis and performance: Implications for riverine food webs

Abstract Alteration of riverine flows can modify the structure and function of ecosystems, changing energy pathways and patterns of micronutrient transfer between trophic levels. Fatty acids (FAs) commonly are used to evaluate food quality, since some FAs required for somatic growth and physiological functions in animals must be obtained from their diet. FAs also are used in food‐web studies as biotracers as a consequence of their constrained metabolic biosynthesis by animals. However, their utility may be confounded by selective retention or modification of dietary FAs by consumers. We conducted a 70‐day feeding trial to compare growth and survival of an abundant and widespread mesoconsumer (Cherax destructor, the common yabby or crayfish) fed three contrasting diets: a poor‐quality detritus‐based diet; a high protein invertebrate diet; and a high‐quality commercial aquaculture pellet. Fatty acid profiles were obtained for each dietary treatment and contrasted with crayfish FA profiles at the end of the experiment to examine patterns of FA retention and integration. We also collected wild crayfish from floodplain wetland and river habitats, and obtained FA profiles from their stomach contents and body tissue to compare with experimental crayfish. Experimental crayfish fed high‐quality commercial pellets doubled in mass during the 70‐day assay, invertebrate fed crayfish growth was intermediate, and growth of crayfish fed detritus was negligible. Fatty acid profiles of crayfish fed our three contrasting diets differed significantly at the end of the experiment. Proportions of the polyunsaturated omega‐6 FA linoleic acid (LIN, 18:2ω6) in crayfish followed the same inequality observed in growth and diets: pellets &gt; invertebrates &gt; detritus. Pellet‐fed crayfish preferentially assimilated greater proportions of FAs 20:4ω6 (ARA), 20:5ω3 (EPA) 18:1ω9 (OA) and 16:1ω7 (POA) into their tissue. Fatty acid profiles of floodplain crayfish differed to profiles of riverine crayfish, and floodplain crayfish had higher proportions of essential FAs ARA and LIN in their tissues. Fatty acid biosynthesis by crayfish was best described by a hypothesis of FA allostasis rather than homeostasis; in this, FA profiles of crayfish were shaped by their diet, and selective integration and modification of high‐quality FAs from basal resources rich in these micronutrients led to higher proportions in crayfish tissues. Here we present evidence for the conversion of shorter‐chain essential FAs by freshwater crayfish to compensate for a lack of long‐chain FAs in their diet. We provide a necessary step for improving our understanding of micronutrient dynamics and the transfer of essential molecules between trophic levels in lowland river food webs. Floodplain habitats are known to provide higher‐quality basal food resources for mesoconsumers than riverine habitats, and here we identify one mechanism by which that may be extended to subsequent trophic levels.

Effect of dietary supplementation with fatty acids on growth, survival, and fatty acid patterns in Procambarus clarkii and Procambarus virginalis: the first comparison of two invasive crayfish species

The red swamp crayfish, Procambarus clarkii, and the marbled crayfish, Procambarus virginalis, are invasive species expanding their ranges on a global scale. Their spread is favored by the fact that these crayfish are also aquaculture species of great economic importance (P. clarkii) or promising prospects in this regard (P. virginalis). This study represents the first attempt to assess the impact of diet supplementation with fatty acids on growth, survival, and fatty acid content in these crayfish species, as well as the first record of fatty acid patterns in the obligate parthenogenetic marbled crayfish. Our results showed that supplementation with saturated palmitic acid increased P. clarkii survival, which has not previously been reported for crustaceans. This positive effect on the part of palmitic acid supplementation was not observed for P. virginalis individuals. Marbled crayfish had significantly higher survival rates than red swamp crayfish regardless of the diet used. The growth of both species was not affected by fatty acid supplementation. Our study indicated that young marbled crayfish had a poorer fatty acid profile than juvenile conspecifics and red swamp crayfish. Fatty acid supplementation and type of diet significantly affected the fatty acid composition in the crayfish tissues. There was an increase in unsaturated α-linolenic acid for P. clarkii and palmitic acid for P. virginalis. Palmitic acid quantitatively dominated in both species regardless of the experimental treatment, with the exception of juvenile P. virginalis, which was fed an oligochaete diet rich in EPA.

Parasite DNA detection in water samples enhances crayfish plague monitoring in asymptomatic invasive populations

Invasive species can facilitate the spread of pathogens by first providing asymptomatic host reservoirs, and then driving disease outbreaks in native populations through pathogen spillover. An example of this are invasive crayfish species in Europe (Faxonius limosus, Pacifastacus leniusculus, Procambarus clarkii), which carry the deadly plague agent (Aphanomyces astaci). Effective disease management requires comprehensive monitoring, however, pathogen detection in carrier populations with low pathogen prevalence and intensities is challenging. We simultaneously collected and analysed crayfish tissue samples of invasive crayfish populations and water samples to compare A. astaci detection in different sample types using quantitative PCR. Combined, the two sampling methods revealed A. astaci presence with DNA concentrations above limit of detection (LOD; the lowest concentration which can be detected with reasonable certainty) in 13 of 23 invasive crayfish populations. In four additional sites, A. astaci DNA concentrations below LOD were found in water. In four populations only were A. astaci concentrations above LOD detected in both sample types and in three populations in concentrations above LOD in tissue but below LOD in water. The likely reason for these discrepancies is the low A. astaci prevalence and concentration in resistant invasive crayfish, which limit detection reliability. Consistency may be improved by timing surveys with seasonal periods of high A. astaci abundance and by increasing water sampling effort. Considering the ease of collecting eDNA samples, compared to crayfish tissue sampling, eDNA methods would facilitate frequent and comprehensive surveys. However, remaining uncertainties in eDNA-based detection reveal the relevance of combining monitoring tools to improve detection of invasive pathogens and their management.

Detection of infectious white spot syndrome virus in red claw crayfish (Cherax quadricarinatus) and red swamp crayfish (Procambarus clarkii) imported into Korea

White spot syndrome virus (WSSV) is one of the most virulent viruses in crustaceans, causing severe economic losses to aquaculture industry. In this study, we tested for the presence of WSSV in the commodity crayfish imported to Korea and also examined the potential infectivity of WSSV in the commodity WSSV-positive crayfish. For the sampling, two species of crayfish, Cherax quadricarinatus (320 red claw crayfish in eight batches) imported from Indonesia and Procambarus clarkii (40 red swamp crayfish in two batches) imported from China, were obtained from fishery markets in Korea. Five representative samples per batch (N = 50) were screened for WSSV using PCR assay, and the virus was detected in five C. quadricarinatus samples and one P. clarkii sample. Among the WSSV-positive samples, the highest virus titer (the copies ranged between 4.93 × 105 and 8.36 × 106 copies/μL) was detected in the P. clarkii sample (20−012) by qPCR, and a comparatively low titer was observed in the C. quadricarinatus sample (20–008) (the copies ranged between 5.94 × 101 and 3.86 × 105 copies/μL). Following the virus infectivity test, WSSV infection was confirmed after feeding WSSV-positive crayfish tissue (20–008, 3.46 × 107 WSSV copies/μL) to Penaeus vannamei (Pacific white shrimp, N = 42) at 5% shrimp biomass. This is the first report of confirmed infectivity of WSSV from the commodity crayfish imported into Korea, suggesting that virus-infected frozen crayfish may present a potential source of viral disease in Korean shrimp aquaculture. Therefore, accurate and strict monitoring of crustacean viruses is required for imported crayfish from foreign countries into Korea.

Development and Validation of an Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry Method to Determine Maduramicin in Crayfish (Procambarus clarkii) and Evaluate Food Safety.

Maduramicin (MAD) is widely introduced into aquatic environments and results in the contamination of fish products. Worryingly, the consumption of MAD-contaminated crayfish (Procambarus clarkii) may induce symptoms of Haff disease. In this study, to monitor this potential contamination and to understand the residue and elimination characteristics of MAD in edible tissues of crayfish, a sensitive and efficient ultra-performance liquid chromatography–tandem mass spectrometry method was developed, validated, and applied. After extraction with acetonitrile and purification by solid-phase extraction column, multiple-reaction monitoring mass spectrometry with positive ionization mode was used to determine MAD’s residues. The limits of detection and of quantification were 6 μg·kg−1 and 20 μg·kg−1, respectively. The fortified recoveries ranged from 74.2% to 110.4%, with relative standard deviation of 1.2% to 10.1%. Furthermore, MAD was completely eliminated after 3 and 5 days from abdominal muscle and hepatopancreas tissues of crayfish, respectively. The maximum residue limits (MRLs) of MAD respectively was 200 μg·kg−1 in muscle and 600 μg·kg−1 in the hepatopancreas, and its withdrawal time in both edible tissues was 25.8 °C·d. Collectively, the results of this study indicate the proposed method is an efficient tool to evaluate the public health risk associated with crayfish consumption.

Evaluation of the nutritional quality of edible tissues (muscle and hepatopancreas) of cultivated Procambarus clarkii using biofloc technology

A 60-day study was conducted to evaluate the growth performance, nutritional quality of edible tissues (muscle and hepatopancreas) of red swamp crayfish (Procambarus clarkii) cultivated using commercial diet feeding (diet group) and biofloc technology (biofloc group). The commercial diet used in the biofloc group was only 60 % of that in the diet group. Glucose and wheat bran were used as additional carbon sources in the biofloc group. The results showed bioflocs was characterized by sufficient protein content but lower lipid content, however, the growth performance of crayfish in the biofloc group were significantly better at the end of the experiment. Besides, the total lipid content in hepatopancreas of crayfish in the biofloc group was higher. Moreover, saturated fatty acid (STA) content in hepatopancreas and monounsaturated fatty acid (MUFA) content in muscle were higher in the biofloc group, while MUFA content in muscle was significantly lower. No significant difference was observed in total amino acid (TAA), essential amino acid (EAA) and essential amino acids index (EAAI) in muscle in both groups. In conclusion, crayfish could be better cultivated using biofloc technology. However, the lipid deficiency and nutritional imbalance of bioflocs would affect the lipid nutritional composition in edible tissues of crayfish.

Fusarium oxysporum causes black gill disease in narrow-clawed crayfish Pontastacus leptodactylus.

Morphological and molecular analyses were carried out to determine the causative agent of black gill disease in narrow-clawed crayfish Pontastacus leptodactylus specimens collected from 6 lakes (Taşkısığı, Beyşehir, Karaidemir, Karataş, Manyas, and Gölhisar) in Turkey. Fungi were isolated from the tissues of crayfish displaying putative black gill disease symptoms. Morphological evaluation was conducted, and the isolates were determined to be similar to Fusarium oxysporum. Subsequent molecular cloning of the ITS region of nrDNA by PCR confirmed species identification; DNA sequences from all 6 isolates were 99% similar to those of F. oxysporum. An experimental infection trial was conducted in triplicate using 1 of the 6 isolates to fulfill Koch's postulates. Three groups of crayfish were used: (1) wounded and contaminated (WC), (2) wounded and not contaminated (WNC), and (3) non-wounded and contaminated (NWC). On Day 3, one individual died in the WC group. Throughout the total 74 d monitoring period, no other mortality was recorded. On Day 14, all crayfish in the WC group showed blackened gills, whereas all crayfish in the NWC displayed partial blackening and all crayfish in the WNC group displayed normal gill coloration. F. oxysporum was re-isolated in pure culture from the WC and NWC groups; thus, the disease was confirmed. Our results indicated that F. oxysporum causes black gill disease in P. leptodactylus crayfish. Moreover, we demonstrated that F. oxysporum can also infect non-wounded crayfish.

Microplastic pollution in water, sediment, and specific tissues of crayfish (Procambarus clarkii) within two different breeding modes in Jianli, Hubei province, China.

This study investigates the occurrence and distribution of microplastics in water, sediment, and crayfish samples within pond and rice-crayfish co-culture breeding modes in Jianli prefecture, China. Microplastics in environmental and biological samples were systematically extracted by CaCl2 solution, digested by H2O2 and KOH, and identified by μ-FTIR. A cleansing treatment for crayfish was performed in pure water before dissection and microplastic accumulation in different tissues (gill, stomach, gut, and flesh) of non-cleansed and cleansed crayfish were compared. The average microplastic abundances were 1.3±0.1-2.5±0.1 particles/L, 0.03±0.01-0.04±0.02 particles/g, and 0.17±0.07-0.92±0.19 particles/individual in water, sediment, and crayfish samples, respectively. Microplastics were detected in all studied crayfish tissues, except the flesh. There were no significant differences in microplastic abundances in water (P=0.82), sediment (P=0.90), and crayfish (P=0.47 for non-cleansed samples; P=0.30 for cleansed samples) between two breeding modes despite the detection of relatively higher microplastic abundances in the samples from the pond breeding mode. Microplastic accumulation in non-cleansed crayfish stomachs and guts (0.71±0.18 particles/individual) was higher (P<0.01) than that recorded in their gills (0.13±0.06 particles/individual). Moreover, microplastics present in the stomachs and guts of cleansed crayfish were significantly less abundant (P<0.01) than in non-cleansed crayfish, although this was not observed in the gills (P=0.99). The majority of microplastic particles in this study had fiber-like shapes, blue and transparent colors, a size smaller than 1mm, and polymer types of PP:PE and PE. The results demonstrate that microplastics in the environment can accumulate in the internal tissues of crayfish, which may pose a potential risk to humans through food consumption without the removal of the gills, stomach, and guts. This study provides valuable information for understanding microplastic accumulation in the different tissues of crayfish and the potential risk of human exposure to microplastics from crayfish as a food supplement.

Crayfish tissue metabolomes effectively distinguish impacts of wastewater and agriculture in aquatic ecosystems

Environmental metabolomics has been proposed as a tool for biomonitoring because organisms regulate production or consumption of metabolites in response to environmental conditions. We evaluated the efficacy of the metabolome of three tissues (hepatopancreas, gill, and tail muscle) from the northern crayfish (Faxonius virilis) to detect and differentiate between impacts of human activities (i.e., reference, municipal wastewater, and agriculture). We conducted a reciprocal transfer study exposing crayfish for 1 or 2 weeks in three streams with different amounts and types of human activities in southern Manitoba, Canada. Tissue samples were analyzed using nuclear magnetic resonance spectroscopy to generate a metabolic profile. Findings indicated the gill tissue metabolome best detected and differentiated between human activities. In particular, the gill metabolome was able to rapidly integrate abrupt changes in environmental conditions associated with municipal wastewater activity. In contrast, the tail metabolome best differentiated between crayfish collected at the reference site from those collected at the two impacted sites. Metabolites extracted from hepatopancreas tissue showed limited and inconsistent detection of among site differences. Based on our findings, we conclude that the metabolome of the northern crayfish can be an effective biomonitoring tool, but monitoring purpose will dictate tissue selection. Indeed, we recommend the gill metabolome be used for short-term assays aimed at detecting acute effects, whereas the tail be applied for survey monitoring aimed at detecting deviations in ecological condition at test sites from reference site conditions.

Ionophore Toxin Maduramicin Produces Haff Disease-Like Rhabdomyolysis in a Mouse Model.

Maduramicin is a toxic ionophore antibiotic that is isolated from Streptomyces, frequently occurring in an aquatic environment. To understand the potential role of maduramicin in crayfish consumption related Haff disease, a mouse model was established in this study. Two exposure routes of maduramicin in the abdominal muscle and the hepatopancreas tissue homogenates of crayfish were given intragastrically to mice in different doses for seven days. Action changes, clinical symptoms, feed consumption, body weight, blood biochemistry, and histopathology examination of mice were observed and analyzed. In the natural exposure group, relatively low concentration of maduramicin in crayfish muscle and hepatopancreas had no obvious effects on mental state, body weight, blood biochemical indexes, or histologic appearance. However, in the artificial exposure group, with increasing concentrations, maduramicin in crayfish muscle and hepatopancreas homogenates both induced mental sluggishness and weight loss of mice. Blood biochemical examination showed that 3.5 mg·kg−1 and 7 mg·kg−1 maduramicin in crayfish tissue homogenates significantly increased levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), lactate dehydrogenase (LDH), and creatine kinase (CK). Additionally, histopathological examination showed that multiple organs were damaged by maduramicin, including degeneration of liver cells, shedding of renal epithelial cells, and disturbance and partial lysis of myocardial and skeletal muscle filaments in the mice. In summary, maduramicin may not cause Haff disease through contamination of the aquatic environment under normal conditions. Maduramicin can be used as a potential toxin tool to establish a rhabdomyolysis disease animal model for drug development.

Variability of elements and nutritional value of spiny-cheek crayfish (Faxonius limosus, Rafinesque, 1817): Variability of elements and nutritional value of F. limosus

Spiny-cheek crayfish (Faxonius limosus, Rafinesque, 1817) females and males were examined as an alternative source of highly valuable material currently sought by the food industry. The aim of the study was to assess the profiles of 14 macro- and microelements (Al, Ca, Cd, Cu, Fe, K, Mg, Na, Ni, P, Pb, Se, Si, Zn) in the meat, exoskeleton and eggs (females) of crayfish collected in the spring and autumn seasons in the Lake Sominko (Poland). The content of heavy metals was analysed, and the degree of their accumulation in crayfish tissues was determined. The profile of the investigated elements in the tested samples was variable depending on the body part, sex of individuals and season of sample collection. A portion of crayfish abdomen meat or eggs (100 g) is particularly rich in P (41.5–73.9 %) of daily requirement), Zn (14.1–38.5 %), Mg (7.9–21.5 %), K (3.3–13.1 %) and Na (4.6–7.7 %) and small quantities of Ca (0.8–2.5 %) and Al (0.9–4.7 %). The study confirmed that consumption of crayfish meat is toxicologically safe and nutritionally complete.

Heavy metal accumulation and health risk assessment of crayfish collected from cultivated and uncultivated ponds in the Middle Reach of Yangtze River

Crayfish, an aquatic food consumed globally, has been reported to accumulate heavy metal. To assess the health risk to the crayfish-consuming population, we investigated heavy metals (Cu, Pb, Zn, Fe, Mn, Cd, Cr, Ba, and As) in crayfish tissues (exoskeleton, abdominal muscle, gills, and hepatopancreas) and sediments from uncultivated and cultivated ponds in the middle reach of the Yangtze River. The metals, except for As, were measured by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and As was measured by atomic fluorescence spectrometry. The distribution of heavy metals differed significantly among tissues and concentrations were generally highest in the hepatopancreas. The average concentrations of heavy metals were higher in crayfish from uncultivated ponds than in crayfish from cultivated ponds. Heavy metal concentrations in crayfish correlated positively with sediment concentrations in uncultivated ponds, indicating that heavy metals can accumulate in crayfish. However, this positive correlation between sediment concentration and crayfish concentration was not observed in cultivated ponds. Source identification, using correlation analysis, indicated that heavy metals in the sediments derive from transportation and agriculture. Based on correlations between heavy metal concentration and body weight, and data on metal distribution in organs, heavy metals accumulate in the hepatopancreas of crayfish in uncultivated ponds, but not in cultivated ponds. Heavy metal concentrations were somewhat higher in female crayfish than in male crayfish and the difference was significant for Fe and Pb. The target hazard quotient (THQ) was used to evaluate non-carcinogenic health risk, with THQ < 1 considered to be safe. All THQ values were < 1, except for Cu in the hepatopancreas (THQ = 1.38) of cultured crayfish and Pb (THQ = 1.01) and Cd (THQ = 1.69) in the hepatopancreas of wild crayfish. Thus, the health risk posed by consuming crayfish, particularly cultured crayfish is low. Our research was designed to protect food safety and the results indicate that the health risk posed by heavy metals in crayfish is low.

Molecular cloning and functional analysis of three STAT isoforms in red swamp crayfish Procambarus clarkii

The Janus kinase (JAK)/signal transducers and activators of transcription (STAT) signaling pathway is associated with the innate immune system and plays crucial roles in the mediation of immune response to viral infections. In this study, three STAT isoform cDNAs were cloned from the red swamp crayfish Procambarus clarkii, and they were designated as PcSTATa, PcSTATb, and PcSTATc. PcSTATa and PcSTATb were generated through the alternative splicing of the last exon, and PcSTATc was produced by intron retention. PcSTATa, PcSTATb, and PcSTATc contained 2382, 2337, and 2274 bp open reading frames encoding proteins with 793, 778, and 757 amino acid residues, respectively. Domain prediction analysis revealed that three isoforms of PcSTATs contain a STAT interaction domain, a STAT all-alpha domain, a STAT DNA binding domain, and a Src-homology 2 domain. The mRNA transcripts of three PcSTAT isoforms were detected in all examined tissues of male and female crayfish. The expression levels of the three PcSTAT isoforms in the hemocytes, gills, and intestines significantly changed after the white spot syndrome virus (WSSV) challenge. PcSTAT silencing by dsRNA interference could positively regulate the expression levels of three anti-lipopolysaccharide factors (PcALF1, PcALF2, and PcALF6) and two crustins (PcCrus1 and PcCrus2) and negatively regulate the expression levels of three ALFs (PcALF3, PcALF4, and PcALF5) and two crustins (PcCrus3 and PcCrus4). These results suggest that all three PcSTAT isoforms are involved in the host defense against WSSV infection.

Effects of freshwater crayfish on influenza A virus persistence in water.

Several investigations have recently assessed the ability of some aquatic invertebrates to act as tools for avian influenza A virus (IAV) surveillance as well as their potential role(s) in IAV ecology. Because of this, as well as the high IAV seroprevalence rates noted in select mesocarnivores that commonly inhabit aquatic and semi-aquatic habitats, we evaluated the effects that freshwater crayfish have on IAV in water at three dose levels and monitored for the presence of IAV in crayfish tissues (gill and green gland) and haemolymph at multiple time points. At relatively high, medium and low (approximately 104 , 103 and 102 EID50 /ml, respectively) doses, mesocosms containing crayfish (Orconectes sp.) had less detectable IAV RNA present when final water samples were assayed (9days post-contact [DPC]). In general, containers without crayfish present had nearly three-fold greater quantities of viral RNA at 9DPC. A varying number of RNA positive samples were detected for the three crayfish sample types collected. Gill tissue produced the largest number of positive non-water samples (n=26), with the highest quantities detected from crayfish sampled on 1 and 4DPC (103.5 EID50 equivalent/ml). On a few occasions, gill (n=8) and haemolymph samples (n=1) produced higher quantities of viral RNA than their respective water samples or water samples collected 1-2DPC earlier, but these differences were typically minor. Based upon water samples, statistical models indicated that the interaction of dose and crayfish exposure days explained most of the variation in these data. Future efforts should address if crayfish exposed to IAV-laden water have the capacity to successfully transmit IAVs to mammals and birds which frequently prey upon them.

Accumulation of trace metals in crayfish tissues: is Procambarus clarkii a vector of pollutants in Po Delta inland waters?

Concentrations of trace elements (Cd, Pb, As, Cu and Zn) were determined in superficial sediments and in hepatopancreas, exoskeleton, and abdominal muscle of the red swamp crayfish Procambarus clarkii from several canals of the Po River Delta area. Sediments of the studied canals exhibited some metal pollution. The hepatopancreas of the crayfish showed a higher concentration of trace metals in comparison to the other tissues at all sites under scrutiny. Concentrations of As and Pb, either in sediment and P. clarkii tissues, were probably related to the use of fertilizers and pesticides. Moreover, the levels of certain metals accumulated in the abdominal muscle (Pb, Cu and Zn) exceeded the threshold values considered harmful to human health. The Toxic Contamination Index, depending on the bioaccumulation data of hepatopancreas and abdominal muscle, allowed us to assess the toxicity by heavy metals of sediments measuring the stress level of the detoxification organ, and resulted in >1 only at two sampling canals. We hypothesize that P. clarkii in the Po River Delta aquatic communities can act as a vector of pollutants, as crayfish can transfer their relatively high amount of heavy metals to higher trophic levels.

Arsenic Uptake and Depuration by Red Swamp Crayfish, Procambarus clarkii

Paddy rice soils, which can contain elevated levels of arsenic, also have importance in crayfish production in Louisiana (USA). In this study, arsenic accumulation and depuration in the tissues of crayfish (Procamborus clarkii) exposed to different As concentrations were determined. For this purpose, crayfish were exposed to 3 different concentrations of As (0,2; 0,8 and 2 mg As L-1) for 14 days and then kept in As free water for following 14 days. Arsenic concentrations were determined in crayfish tissues (gill, muscle, exoskeleton, hepatopancreas) during both the accumulation (1, 3, 7 and 14th days) and depuration (15, 17, 21, and 28th days) phases. During the accumulation period, arsenic concentration in the tissues was found to increase proportionally with time and exposure concentrations: gill &amp;gt; hepatopancreas &amp;gt; exoskeleton &amp;gt; muscle. During this period, however, the arsenic concentration in the tissues did not reach the equilibrium. In the depuration phase, arsenic elimination varied ranging between 54.63-87.91% in the hepatopancreas, 42.69 to 74.21% in the gills, 35.56-73.55% in the exoskeletons and 26.75-49.84% in the muscles.

Food safety risk assessment of metal pollution in crayfish from two historical mining areas: Accounting for bioavailability and cooking extractability

Here we characterize the bioaccumulation of mercury (Hg) and lead (Pb) in red swamp crayfish (Procambarus clarkii) from two river courses in Central Spain that are impacted by historical Hg and Pb mining activities, respectively. We estimate the absolute oral bioavailability of metals in crayfish tissues by means of in vitro bioaccessibility simulations, and assess whether their consumption may imply a health risk for humans by estimating target hazard quotients and safe consumption rates. We also study the effect of cooking crayfish on the mobilization of the metal body burden in the context of the traditional Spanish cuisine. The results showed that crayfish from the mining districts accumulated a high level of Hg and Pb pollution in both the tail muscle and the carcass. The in vitro bioaccessibility of Hg and Pb in the edible part was 27.86 ± 4.05 and 33.73 ± 5.91%, respectively. Absolute bioavailability was estimated to be 38.31 for Hg, and 20.21 (adults) and 67.35% (children) for Pb. Risk indices indicated that, even after adjusting for bioavailability, it is not safe to consume crayfish from the mining-impacted rivers because of their high levels of Hg and Pb. Using the carcass as a condiment for flavouring should also be avoided. The cooking procedure extracted relatively small amounts of the total Hg (8.92 ± 2.13%) and Pb (1.68 ± 0.29%) body burden. Further research that will support human and ecological risk assessment, along with the implementation of advisory measures for the local population as regards crayfish consumption, are recommended.

Invasive rusty crayfish (Faxonius rusticus) populations in North America are infected with the crayfish plague disease agent (Aphanomyces astaci)

The American rusty crayfish, Faxonius rusticus, is an invasive species in parts of North America where it displaces native crayfish species. In Europe, various invasive North American crayfish species are carriers of the crayfish plague disease agent Aphanomyces astaci that causes devastating population declines of European crayfish. Little is known about either the presence or the influence of A. astaci in North America where it originates. Here, we attempted to isolate A. astaci from North American F. rusticus for the first time and compare it to the strains detected in Europe. We tested the infection status of 84 F. rusticus samples from 10 different locations in the midwestern United States that are outside of the F. rusticus native distribution range. We used quantitative real-time PCR (qPCR) to assess the infection status in each individual, and we determined the mitochondrial haplotypes and multilocus microsatellite genotypes when it was possible. We detected A. astaci DNA in 9 individuals from 4 out of 10 locations. Analyses of the axenic culture isolates and the crayfish tissue samples by sequence analyses, haplotyping, and genotyping confirmed the results and revealed a novel A. astaci microsatellite genotype. Our results clearly identify F. rusticus as a host of A. astaci in North America. The threat of these strains to endangered crayfish species in North America remains unknown, but the potential of A. astaci infections should be considered when developing and implementing invasive species management plans for conservation purposes.

Improved method for genotyping the causative agent of crayfish plague (Aphanomyces astaci) based on mitochondrial DNA.

Aphanomyces astaci causes crayfish plague, which is a devastating disease of European freshwater crayfish. The likely first introduction of A. astaci into Europe was in the mid-19th century in Italy, presumably with the introduction of North American crayfish. These crayfish can carry A. astaci in their cuticle as a benign infection. Aphanomyces astaci rapidly spread across Europe causing the decline of the highly susceptible indigenous crayfish species. Random amplified polymorphic DNA-PCR analysis of A. astaci pure cultures characterized five genotype groups (A, B, C, D and E). Current A. astaci genotyping techniques (microsatellites and genotype-specific regions, both targeting nuclear DNA) can be applied directly to DNA extracted from infected cuticles but require high infection levels. Therefore, they are not suitable for genotyping benign infections in North American crayfish (carriers). In the present study, we combine bioinformatics and molecular biology techniques to develop A. astaci genotyping molecular markers that target the mitochondrial DNA, increasing the sensitivity of the genotyping tools. The assays were validated on DNA extracts of A. astaci pure cultures, crayfish tissue extractions from crayfish plague outbreaks and tissue extractions from North American carriers. We demonstrate the presence of A. astaci genotype groups A and B in UK waters.