Crayfish Tissues Research Articles

An autophagy-related gene ATG14 promotes WSSV infection by facilitating autophagy in Cherax quadricarinatus

The activation of autophagy was found to be positively correlated with white spot syndrome virus (WSSV) entry into host cells; however, the molecular regulation between autophagic initiation and WSSV entry is still poorly known. Herein, ATG14, a major member of autophagy initiation complex class III phosphatidylinositol-3-kinase (PI3KC3) complex 1 (PI3KC3-C1), playing a vital role in the formation of autophagy precursors, was studied on WSSV infection in a crustacean Cherax quadricarinatus. The CqATG14 gene was cloned with 1476 bp encoding 491 amino acids, which was widely expressed in all examined tissues of crayfish with the highest expression in hemocytes. Moreover, the gene expression of CqATG14 was significantly up-regulated at 6 and 12 hpi in crayfish hematopoietic tissue (Hpt) after WSSV infection. Importantly, the internalized WSSV virions was clearly decreased at an early infection stage of 2 hpi in CqATG14-silenced Hpt cells, causing the decrease of viral replication as the expression of both WSSV genes and viral protein VP28 were significantly down-regulated at a late infection stage after CqATG14 knocking down. Furthermore, the binding of CqATG14 to CqBeclin1 was determined by co-immunoprecipitation assay; meanwhile, the presence of CqGABARAP-II protein (a marker of autophagy activation) was significantly decreased in CqATG14-silenced Hpt cells. These data suggest that CqATG14 might promote the early infection of WSSV, probably resulting from the promotion of viral endocytosis via facilitating autophagy, which benefits the further exploration of molecular mechanism around WSSV-autophagy in crustaceans.

Microcystins in the benthic food-web of the Sacramento-San Joaquin Delta, California

Harmful cyanobacteria blooms are a growing threat in estuarine waters as upstream blooms are exported into coastal environments. Cyanobacteria can produce potent toxins, one of which—hepatotoxic microcystins (MCs)—can persist and accumulate within the food web. Filter-feeding invertebrates may biomagnify toxins up to 100× ambient concentrations. As such, bivalves can be used as an environmentally relevant and highly sensitive sentinel for MC monitoring. To date there has been little research on cyanotoxin bioaccumulation in estuaries. The Sacramento-San Joaquin Delta (Delta) aquatic food web has undergone a profound change in response to widespread colonization of aquatic invasive species such as Asian clams (Corbicula fluminea) in the freshwater portion of the Delta. These clams are prolific—blanketing areas of the Delta at densities up to 1000 clams/m2 and are directly implicated in the pelagic organism decline of threatened and endangered fishes. We hypothesized that Asian clams accumulate MCs which may act as an additional stressor to the food web and MCs would seasonally be in exceedance of public health advisory levels. MCs accumulation in Delta Asian clams and signal crayfish (Pacifastacus leniusculus) were studied over a two-year period. ELISA and LC-MS analytical methods were used to measure free and protein-bound MCs in clam and crayfish tissues. We describe an improved MC extraction method for use when analyzing these taxa by LC-MS. MCs were found to accumulate in Asian clams across all months and at all study sites, with seasonal maxima occurring during the summer. Although MC concentrations rarely exceeded public health advisory levels, the persistence of MCs year-round still poses a chronic risk to consumers. Crayfish at times also accumulated high concentrations of MCs. Our results highlight the utility of shellfish as sentinel organisms for monitoring in estuarine areas.

Concentrations, sources and health risk of bisphenols in red swamp crayfish (Procambarus clarkii) from South-Eastern China

Bisphenol analogs (BPs) are extensively employed in commercial and industrial products and they have been found in a variety of environmental matrices and human samples. The red swamp crayfish (Procambarus clarkii) has been a trendy food in China in recent decades. However, the levels of BPs in Chinese crayfish and the associated hazards of human exposure remain unknown. Thus, in this study, the levels of eight BPs in crayfish gathered from five major provinces engaged in crayfish within the Yangtze River Basin were analyzed. Additionally, the health risks for humans by ingesting crayfish were calculated. BPs were frequently detected in crayfish tissues, indicating the wide occurrence of these chemicals. In comparison to other substitutions, BPA remains the dominant bisphenol analog. Most of the BPs were observed to accumulate in the hepatopancreas compared to the muscle, so consuming the hepatopancreas of crayfish is not recommended. With the exception of BPS, the Estimated Daily Intakes (EDIs) of the remaining BPs exceeded the Tolerable Daily Intake (TDI) specified by the European Food Safety Authority (EFSA) by a factor of 1.75–69.0. The mean hazard index (HI) values exceeded 1 for both hepatopancreas and muscle in all provinces, and the mean HI values for hepatopancreas were significantly higher than those for muscle, indicating potential health risks for local consumers.

PcASTA in Procambarus clarkii, a novel astaxanthin gene affecting shell color

The color of crayfish (Procambarus clarkii) shells not only affects their value, but also has a significant impact on individual size. Astaxanthin is a common carotenoid that has been found in many studies to have different functions, including regulating body color formation. In this study, the levels of different carotenoids were detected using high performance liquid chromatography (HPLC) and found a significant correlation between astaxanthin content and shell color. An astaxanthin gene (PcASTA) was identified from P. clarkii, and it was expressed in tissues of crayfish with dark-red shells and green shells. The highest expression levels of PcASTA were found in the hepatopancreas, followed by the muscle. The expression of PcASTA in all tissues of red shell crayfish was higher than that of green shell crayfish, indicating that PcASTA may be involved in shell color formation in crayfish. Moreover, high water temperature and feeding β-carotene can lead to an increase in tissue expression of PcASTA and astaxanthin content in crayfish shells. The findings indicate that PcASTA may affect shell color in P. clarkii by being involved in astaxanthin synthesis and transformation.

Рівні накопичення важких металів та активності радіонуклідів у вузькопалих річкових раках (Astacus leptodactylus Eschscholtz, 1823) Кам’янського та Запорізького (Дніпровського) водосховищ

Purpose. To determine the content of heavy metals as well as natural and artificial radionuclides in muscle tissue and carapaces of narrow-clawed crayfish Astacus leptodactylus of the Kamianske and Zaporizhzhia (Dnipro) reservoirs. Methodology. The material for the study were narrow-clawed crayfish collected in the spring period (March-April) 2021 in the coastal zone of the Kamianske and Zaporizhzhia (Dnipro) reservoirs. The collection of material was carried out with standard open-type crayfish traps with a mesh size No. 20, manual collection in the littoral zone as well as with the help of special baited traps. Carapaces and muscle tissue of crayfish were used to determine the content of heavy metals and radionuclides. Preparation of samples for measuring the content of heavy metals and radionuclides was carried out by separating crayfish tissues with subsequent homogenization and concentration (drying and incineration) of the collected material. The samples were dried at a temperature of +105°С to a constant weight, and then incinerated at a temperature of +450°С to obtain white ash. The content of radionuclides was determined on a gamma-beta spectrometer SE-BG-01 “AKP”. The content of heavy metals was determined on an atomic absorption spectrophotometer C115-M1 with a flame analyzer. Findings. Zn, Fe, and Cu were actively accumulated in the muscle tissue of crayfish of the Kamianske and Zaporizhzhia (Dnipro) reservoirs. This fact is explained by the intensive accumulation of elements in crayfish body that actively occurred in the course of physiological processes. Heavy metals such as Mn, Pb, Co were the most accumulated in crayfish carapace. The minimum content of heavy metals was found for Сd. It was found that Pb, Cu, Zn and Cd contents exceed the MACs in muscles of crayfish of the Zaporizhzhia (Dnipro) reservoir by 8, 6, 6.2 and 1.65 times, respectively. The norms for the content of heavy metals in the muscle tissue of river crayfish have not been established in Ukraine today, however, a comparison of the data we obtained with the norms for live fish shows a significant excess for almost all heavy metals examined. It was found that the level of radionuclide activity of in the muscle tissue of decapods of both investigated reservoirs was due to 40K, in the carapaces - 226Ra; 90Sr activity was minimal in muscles, and 226Ra activity in carapaces. Accumulation of studied radionuclides in crayfish did not exceed the MACs for crayfish as a food product. Originality. For the first time, the levels of accumulation of heavy metals and the activity of radionuclides in the muscle tissue and carapace of narrow-clawed crayfish of the Kamianske and Zaporizhzhia (Dnipro) reservoirs were determined. The content of toxic elements that are subject to control in food raw materials and food products according to the MACs in crayfish of the Kamianske and Zaporizhzhia (Dnipro) reservoirs was determined. Practical value. The results of the work can be used during monitoring of the ecotoxicological and radioecological conditions of the aquatic environment. Also, the obtained results can be applied in the study of narrow-clawed crayfish of the Dnieper River basin. Keywords: heavy metals, radionuclides, accumulation coefficient, MAC, crayfish, Zaporizhzhia (Dnipro) Reservoir, Kamianske Reservoir.

Toxicological effects of diclofenac on signal crayfish (Pacifastacus leniusculus) as related to weakly acidic and basic water pH

The widespread use and continuous discharge of pharmaceuticals to environmental waters can lead to potential toxicity to aquatic biota. Pharmaceuticals and their metabolites are often complex organic and environmentally persistent compounds that are bioactive at low doses. This study aimed to investigate the effects of diclofenac (DCF) on the antioxidant defence system and neurotoxicity biomarkers in signal crayfish (Pacifastacus leniusculus) under weakly acidic and basic conditions. Crayfish were exposed to 200 µg/L of DCF at pH 6 and 8 for 96 h and subsequently underwent the depuration phase for 96 h. Gills, hepatopancreas, and muscle were sampled after the exposure and depuration phases to assess the toxicological biomarker responses of DCF in crayfish by evaluating lipid peroxidation (LPO) levels, activities of antioxidant enzymes and acetylcholinesterase. After the exposure phase, the hemolymph DCF concentration was detected one order higher at pH 6 than at pH 8. The DCF was subsequently fully eliminated from the hemolymph during the depuration phase. Our results showed that DCF caused alteration in the activities of six of the seven tested biomarkers in at least one crayfish tissue. Although exposure to DCF caused imbalances in the detoxification system on multiple tissue levels, it was regenerated to a balanced state after the depuration phase. Integrated biomarker response (IBRv2) showed that the highest toxicological response to DCF exposure was elicited in the gills, whereas the hepatopancreas was the highest-responding tissue after the depuration phase. Exposure to DCF at pH 6 caused higher toxicological effects than at pH 8; however, crayfish antioxidant mechanisms recovered more quickly at pH 6 than at pH 8 after the depuration phase. Our results showed that water pH influenced the toxicological effects of DCF, an ionisable compound in crayfish.

Microcystin profiles in European noble crayfish Astacus astacus and water in Lake Steinsfjorden, Norway

Lake Steinsfjorden, an important noble crayfish (Astacus astacus) habitat, is often affected by blooms of Planktothrix spp. that produce microcystins (MCs). A poor correlation between MCs by ELISA in the water and in crayfish tissue in a study in 2015 prompted further investigation by LC–HRMS. LC–HRMS analyses of filters from water samples and on selected crayfish tissue extracts from the 2015 study revealed the presence of known and previously unreported MCs. Crayfish samples from May and June 2015 were dominated by MCs from the Planktothrix bloom, whereas in September novel MCs that appeared to be metabolites of MC-LR were dominant, even though neither these nor MC-LR were detected in the water in 2015. A water sample from October 2016 also showed MCs typical of Planktothrix (i.e., [d-Asp3]- and [d-Asp3,Dhb7]MC-RR and -LR), but low levels of MC-RR and MC-LR were detected in the lake water for the first time. In late summer and autumn, the MC profiles of crayfish were dominated by the homonorvaline (Hnv) variant MC-LHnv, a putative metabolite of MC-LR. Taken together, ELISA, LC–HRMS and previous PCR analyses showed that although Planktothrix was part of the crayfish diet, it was not the sole source of MCs in the crayfish. Possibly, crayfish in Lake Steinsfjorden may be ingesting MCs from benthic cyanobacteria or from contaminated prey. Therefore, information on the cyanobacterial or MC content in the water column cannot safely be used to make predictions about MC concentrations in the crayfish in Lake Steinsfjorden. Interestingly, the results also show that targeted LC–MS analysis of the crayfish would at times have underestimated their MC content by nearly an order of magnitude, even if all previously reported MC variants had been included in the analysis.

Molecular detection of Aphanomyces astaci – An improved species specific qPCR assay

The parasitic oomycete Aphanomyces astaci is the causative agent of crayfish plague, a devastating disease for European freshwater crayfish. Species specific quantitative real-time PCR (qPCR) can offer rapid detection of the pathogen. However, the well established A. astaci qPCR assay recommended by the World Organization for Animal Health (WOAH) amplifies the recently described Aphanomyces fennicus. Consequently, false-positive results may occur. This calls for the improvement of the established species specific A. astaci qPCR assay in order to avoid amplifying A. fennicus while screening for A. astaci.We developed an improved species specific A. astaci qPCR assay and validated the assay across three laboratories, using established procedures including different qPCR master mixes for each respective laboratory. Genomic DNA from A. astaci, A. fennicus and closely related Aphanomyces spp. was analysed and compared with both the improved and established assay. Additionally, DNA from crayfish tissue and environmental samples were analysed with both assays. The improved assay showed similar sensitivity with the established assay for all sample types, while proving highly specific for A. astaci avoiding amplification of A. fennicus and the other tested Aphanomyces spp.Environmental DNA (eDNA) samples collected at River Lierelva in Norway amplified with the established assay, but not with the improved assay indicating false positive. We were able to sequence a 530 bp fragment of the ITS region from these eDNA samples and the consensus sequence showed 99.9–100 % pairwise identity with A. fennicus and 97.2–98 % pairwise identity with A. astaci, suggesting that the occurrence of A. fennicus is not limited to Finland, where it was first discovered.

Aeromonas salmonicida subsp. Masoucida causes an emerging infectious diseases and immune response in red swamp crayfish (Procambarus clarkii)

In this study, the characteristics of a dominant strain wx3 isolated from the tissues of several sick red swamp crayfish were studied, and the immune response of the red swamp crayfish under stress was analyzed. The whole genome analysis of wx3 identified it as Aeromonas salmonicida subsp. Masoucida, which was confirmed using the bacterial challenge test, and is the pathogen that causes red swamp crayfish head rot. The sensitivity of wx3 to a variety of antibiotics was found that wx3 was highly sensitive to 13 antibiotics, but was not sensitive to 4 antibiotics. Comparative transcriptome analysis showed that 811 differentially expressed genes (DEGs) were enriched in the hepatopancreas 48 h after wx3 infection. The KEGG pathway analysis and GO analysis detected differentially expressed immune related genes, including C-type lectin 3 and Hsp22, which were upregulated, and also enriched in immune related pathways, such as the C-type lectin receptor signaling pathway, etc. In conclusion, by analyzing transcriptome, we found that red swamp crayfish infected with wx3 can exert a strong immune response.

P10-06: Potential of crayfish tissue cells for ecotoxicology studies

P10-06: Potential of crayfish tissue cells for ecotoxicology studies

The Accumulation of Toxic Elements (Pb, Hg, Cd, As, and Cu) in Red Swamp Crayfish (Procambarus clarkii) in Qianjiang and the Associated Risks to Human Health.

Due to rapidly expanding crayfish consumption worldwide, the food safety of red swamp crayfish (Procambarus clarkii) is of great concern. China is the largest consumer and producer of crayfish globally. As of yet, it is unknown whether the main crayfish production cities in China are within safe levels of toxic heavy metals and metalloids. For 16 consecutive years, Qianjiang city ranked first in China in processing export volumes of red swamp crayfish. This study presents a comprehensive analysis of the enrichment levels and associated health risks of the species in Qianjiang. In our research, samples of four crayfish tissues, including the head, hepatopancreas, gills, and muscles, were collected from 38 sampling sites distributed in Qianjiang to evaluate the concentration levels of five heavy metals (Pb, Hg, Cd, As, and Cu). The concentration levels of all five metals in muscle did not surpass the national standard. Furthermore, eight significant correlations have been found. For further in-depth assess risk of crayfish in Qianjiang, estimated daily intake (EDI), target hazard quotient (THQ), carcinogenic risk (CR), and estimated maximum allowable consumption rates (CRmm) were evaluated in the abdomen muscle and hepatopancreas. The THQ values for each metal were found to be less than 1, while the CR values were below 10-6. Additionally, the CRmm for adults was determined to be 17.2 meals per month. These findings, based on the analysis of five metallic elements included in this study, suggest that the consumption of crayfish abdomen muscle in Qianjiang does not pose any significant health risks. However, it is noteworthy that certain regions exhibit elevated levels of arsenic in the hepatopancreas, surpassing the national standard, thereby rendering them unsuitable for excessive consumption. In general, the findings can be used to provide guidance for safe dietary practices in China.

Accumulation of antibiotics and antibiotic resistance genes in freshwater crayfish - Effects of antibiotics as a pollutant.

• Antibiotic resistance genes were analyzed in crayfish faeces. • Crayfish can accumulate antibiotic resistance genes in their intestine after a short time of SMX exposure. • Low concentration of sulfamethoxazole in the surrounding water causes accumulation of this antibiotic in crayfish tissues.

Factors influencing accumulation of Zn, Cu, and Ca in the tissues of spiny-cheek crayfish (Faxonius limosus, Rafinesque, 1817)

Both physicochemical and biological factors affect the degree of metal accumulation in crayfish tissues. The content of metals and correlations between the metal concentrations in different tissues and the total length of crayfish is suitable indicators of contamination of the aquatic environment. The aim of the study was to analyse the effect of age and sex of crayfish on the degree of accumulation of Ca, Cu, and Zn in the muscle and exoskeleton. A total of 100 individuals of the spiny-cheek crayfish (Faxonius limosus, Rafinesque, 1817) were caught from Głowińsk reservoir (Poland) in October 2019 using fyke nets. Metal concentrations were determined in freeze-dried samples of the abdominal muscle, exoskeleton, bottom sediment, and water using atomic absorption spectroscopy (AAS). Here, we show that the highest concentrations of Zn were found in the muscle of 4-year-old females, Cu in 3-year-old males, and Ca in 4-year-old males. Sex was a significant factor affecting the content of Ca in the muscle and Zn in the exoskeleton. Age was a significant factor affecting the content of Zn, Cu, and Ca in the muscle and Zn and Cu in the exoskeleton. The bioconcentration factor (BCF) of Zn and Cu in the muscle and exoskeleton of spiny-cheek crayfish was much higher from water than from sediments, unlike Ca. Furthermore, we found significant correlation for muscle between Zn and total length in 3-year-old females and 4-year-old males and between Cu and TL in 3-year-old males. Analysing the recommended daily intake (RDI) for the investigated minerals confirmed that the consumption of 100 g of spiny-cheek crayfish muscle could meet daily requirement for Zn up to 27.5%, for Ca in 12.4%, and over 100% for Cu. The conducted analyses confirmed that the consumption of crayfish meat was safe for the health of potential consumers in terms of the analysed metal content.

Effect of dietary Bacillus subtilis supplement on Cd toxicokinetics and Cd-induced immune and antioxidant impairment of Procambarus clarkii.

Cadmium (Cd), a non-biodegradable contaminant in freshwater ecosystems, can pose a serious threat to aquatic animals at high levels. In this study, the Cd toxicokinetics and the immune and antioxidant defense were explored in Procambarus clarkii exposed to different levels of Cd (0, 0.1, 1.0mg Cd/L) or treated with 1.0mg Cd/L and dietary Bacillus subtilis supplementation (1 × 107cfu/g). Results from the 21-day uptake and depuration experiment revealed that Cd exposure elicited a dose- and time-dependent uptake in all crayfish tissues, and the rank order of Cd concentration was gill > hepatopancreas > exoskeleton > muscle. The one-compartment model demonstrated that gills had the highest uptake rate (ku) value after Cd aqueous exposure and the ku and elimination rate (kd) values in gill, hepatopancreas, and exoskeleton of the group with 1.0mg Cd/L were higher than those of the group at alow Cd concentration (0.1mg Cd/L). However, B. subtilis could decrease Cd ku and increase Cd kd in hepatopancreas, resulting in the reduction of bioconcentration factors (BCF), steady-state concentrations (Css), and biological half-life (Tb1/2). A positive correlation was found between aqueous Cd concentration and the severity of hepatopancreas histopathological injury, while B. subtilis could ameliorate the pathological damage in the high Cd group. Similarly, aqueous exposure to Cd elevated malonaldehyde (MDA) content and suppressed the activities of lysozyme (LZM), acid phosphatase (ACP) in hepatopancreas and alkaline phosphatase (AKP) in hemolymph. The activities of superoxide dismutase (SOD) and catalase (CAT) in hepatopancreas were also inhibited. Nevertheless, they were all recovered with the dietary addition of B. subtilis. In conclusion, our results indicated that exposure to Cd significantly increased Cd accumulation and toxic damages in crayfish hepatopancreas, while dietary administration of B. subtilis to crayfish significantly decreased Cd accumulation and improved the immune and antioxidant defense, leading to the prevention in toxic effects of Cd.

Exposure and Health Risk Assessment of Per- and Polyfluoroalkyl Substances in Crayfish from the Middle and Lower Reaches of the Yangtze River

Per- and polyfluoroalkyl substances (PFASs) are a novel class of emerging persistent organic pollutants (POPs) owing to their environmental persistence and bioaccumulation. Red swamp crayfish is a major source of exposure to PFASs, while the dietary intake of PFASs from crayfish is still unclear. We investigated the concentrations of PFASs in 130 batches of crayfish and 100 environmental samples from Middle and Lower Reaches of the Yangtze River Delta. Seven Perfluoroalkyl carboxylic acids (PFCAs), 3 Perfluoroalkyl sulfonates (PFSAs), and 6:2 Cl-PFESA were analyzed by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Meanwhile, PFASs exposure levels were examined concretely in four tissues of crayfish and different circulation links. The average daily intake (ADI) risk model was used to evaluate the human health risk of consuming crayfish and suggested that the risk of PFASs exposure is at a low level.

Bioaccumulation, Biosedimentation, and Health Hazards of Elements in Crayfish, Procambarus clarkii from El-Rahawi Drain and El-Qanatir in the River Nile, Egypt

Elements accumulation in crayfish is proportional to the increase in bioavailability (direct contact) with the surrounding water, sediment, and feeding. Five heavy metals (Cu, Cr, Mn, Ni, and Ag) and lithium (Li) were analyzed in the sediment, water, and crayfish tissues. Elements (heavy metals and lithium) concentrations in sediment, water, and crayfish tissues showed significant differences between the two sampling stations (El-Qanatir and El-Rahawi drain). However, the levels of elements in crayfish tissues were arranged in declining order as hepatopancreas > gills > exoskeleton > muscles for Cu and Cr; hepatopancreas > exoskeleton > gills > muscles for Ni and Ag; and exoskeleton > gills > hepatopancreas > muscles for Li and Mn. The human health hazard evaluation of heavy metals and lithium exposure via edible tissue consumption was assessed for both children and adult consumers. The target hazard quotient THQ values of crayfish edible tissues (less than 1) will not impose any health implications for consumers who ingest edible tissues in sufficient quantities. Furthermore, the hazard index (HI) values reported for children and adult consumers were lower than one, indicating non-carcinogenic and carcinogenic hazards, suggesting that crayfish edible tissues are safe for human ingestion. This evidence also found that Procambarus clarkii could be a good bio-indicator organism for monitoring potentially metals in aquatic systems.

Residue, biotransformation, risk assessment and withdrawal time of enrofloxacin in red swamp crayfish (Procambarus clarkii)

Crayfish is a very popular aquatic food in many countries, and enrofloxacin (ENR) and ciprofloxacin (CIP) was the most frequently detected in aquatic products. However, limited information is available on the residue characterization, biotransformation rate and withdrawal period (WT) of ENR and CIP in crayfish and health risk via consumption of ENR and CIP remained crayfish. Herein, a comprehensive investigation was conducted to study residue depletion, biotransformation, ingestion risk, and WT of ENR and its predominate metabolite CIP in crayfish following different routes with repeated doses. The results showed that the elimination half-life (T1/2) of target compounds in crayfish were all in order of hepatopancreas > muscle > gill, and the order of T1/2 in different crayfish tissues were intramuscular (IM) route > oral (PO) treatment > immersion (IMMR) administration. The biotransformation rates from ENR to CIP varied from 0.75% to 3.45% in crayfish tissues following different exposure routes. The high dietary risk (RQ > 1) consuming muscle and hepatopancreas of ENR and CIP remained crayfish occurred at early after different administrations. WT is the key to control the drug residue risk, and the longest WT of marker residue of ENR in crayfish was calculated to be 51 d (1275 °C-day).

Heavy Metals and their Effects on Macroinvertebrates Present in the Ojo River, Lagos, Nigeria

Aim: To provide information regarding the presence of heavy metals in the tissues of crab (Potamon fluviatile), prawn (Macrobrachium rosenbergii), and crayfish (Metanephrops australiensis) obtained from the Ojo river of Lagos State, Nigeria.
 Study Design: Commercially sold marine crustacean samples (crab, prawn, and crayfish) obtained from the Ojo river of Lagos, Nigeria, were assessed for the presence of heavy metals, and also the potential health risks for local consumers.
 Place and Duration of Study: Ojo river, located close to Ojo local government secretariat, Ojo, Lagos State, Nigeria.
 Methodology: Live samples of macroinvertebrates such as Metanephrops australiensis, Potamon fluviatile, and Macrobrachium rosenbergii were purchased from the fishermen at the riverside in Ojo and immediately transferred to the laboratory. The samples were oven-dried and ground into a fine powder, then subjected to sample digestion and finally atomic absorption spectrophotometer (AAS), to obtain the various heavy metal concentrations present in each sample.
 Results: The result indicated variations in the metal body load among species. All the metals were below the FAO/WHO permissible limit for food consumption except for Cd in crayfish which was slightly beyond the set limit. The highest concentration examined were found in crayfish, followed by crab and prawn. Zinc and iron were of higher concentrations in the tissues of the macroinvertebrates while lead was the least concentrated metal present only in the tissues of crayfish and absent in the tissues of both crab and prawn.
 Conclusion: The human health risk evaluation for the marine organisms indicated that both the crab and the prawn samples examined were safe for consumption, while crayfish may not be considered safe for consumption. Also, the potential health risk from consuming seafood exposed to these metals should not be ignored.

Extraction of biodegradable microplastics from tissues of aquatic organisms

Biodegradable plastics (BPs) have been given high hopes to substitute conventional plastics, but their biodegradation requires strict conditions. BPs can accumulate for a long time in the environment and even derive biodegradable microplastics (BMPs), thus threatening wildlife and ecosystems. However, no efficient method is available for extracting BMPs from organisms' tissues. This study used multi-criteria decision-making (MCDM) methods to comprehensively evaluate and optimize extraction protocols of five BMPs from economic aquatic species. Digestion time, digestion efficiency, mass loss, cost, polymer integrity and size change were selected as evaluating indictors. According to the screening results of MCDM methods, Pepsin+H2O2 was selected as the optimal digestion method of BMPs because of its highest comprehensive score, which has high digestion efficiency (99.56%) and minimum plastic damage. Compared with olive oil, NaI is more suitable for separating BMPs from the digested residues. Furthermore, the combination of Pepsin+H2O2 digestion and NaI density separation was used to extract all five kinds of BMPs from the bivalve, crab, squid, and crayfish tissues, and all the recovery rates exceeded 80%. These results suggest that the optimal protocol is practicable to extract various BMPs from various aquatic organisms.

Creating a baseline for bioaccumulation in crayfish in the central Appalachian coalfields

Cambarus veteranus and Cambarus callainus are highly imperiled crayfish that are federally listed. These crayfish are native to the coalfields region of central Appalachia. The dominant industry and land use in this region is coal mining. The most common method of mining in this area, surface mining, employs large ponds to hold a slurry water byproduct created when cleaning the coal. Intermittently, the containment structures for these ponds fail causing the uncontrolled release of coal slurry. There is a lack of data on the rates of bioaccumulation of elements commonly associated with mining in crayfish within this region before and after these spills occur, such that there is no reference to know what concentrations constitutes “normal” rates. Chemical pollutants along with increased sedimentation from industrial sources are known to cause adverse effects in crustaceans and can be lethal. Therefore, it is crucial to better understand what baseline conditions of bioaccumulation are within this region before spills occur. This study assessed the bioaccumulation of magnesium (Mg), aluminum (Al), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), and lead (Pb) in non-imperiled crayfish by analyzing hepatopancreas and gill tissues. We analyzed rates of bioaccumulation grouped by crayfish genus and tissue type throughout each season Differences between genus and tissue type, reference and degraded sites, and between crayfish tissue type, periphyton, and water were also investigated. Seasonal variation in the concentrations of elements in crayfish tissue was found with higher element concentrations during winter and lower concentrations during summer. Differences between crayfish tissue type, periphyton, and water were also found, with periphyton typically having the highest concentrations, water having the lowest concentrations, and crayfish tissue being between concentrations found in water and periphyton.