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In this study, Crayfish Optimization Algorithm (COA) was examined. COA, which simulates crayfish's summer resort behavior, competition behavior, and foraging behavior. COA is a successful heuristic algorithm originally proposed for continuous optimization problems. In this study, the continuous search space of COA was converted into a binary search space with eight different S- and V-shaped transfer functions. Thus, the Binary COA (BinCOA) algorithm was proposed to the literature. The success of BinCOA variations was analyzed on 25 different knapsack problems of different sizes. The most successful transfer function was determined as BinCOAV1. Since the success of BinCOAV1 fell behind many binary heuristic algorithms in the literature, BinCOA was developed with two different methods (bitwise operator and repair method). Thus, the Improved BinCOA (IBinCOA_RX) algorithm was proposed in this study. BinCOA's local search ability and discovery ability in the binary search space have been improved. The resulting improved BinCOA variations (IBinCOAX (BinCOA with bitwise operator), IBinCOAR (BinCOA with repair method), and IBinCOA_RX (BinCOA with bitwise operator and repair method)) were analyzed in detail and the effect of each method added to BinCOA was detailed in the paper. The success of IBinCOA_RX has been proven by comparing it with eight different binary heuristic algorithms selected from the literature. According to the results, the IBinCOA_RX algorithm showed preferable success for binary optimization problems. In addition, in this study, the effectiveness of BinCOAV1 and IBinCOAX algorithms is also shown on a different binary problem, namely the uncapacitated facility layout problem (UFLP). [ABSTRACT FROM AUTHOR]

In high-dimensional scenarios, trajectory planning is a challenging and computationally complex optimization task that requires finding the optimal trajectory within a complex domain. Metaheuristic (MH) algorithms provide a practical approach to solving this problem. The Crayfish Optimization Algorithm (COA) is an MH algorithm inspired by the biological behavior of crayfish. However, COA has limitations, including insufficient global search capability and a tendency to converge to local optima. To address these challenges, an Enhanced Crayfish Optimization Algorithm (ECOA) is proposed for robotic arm trajectory planning. The proposed ECOA incorporates multiple novel strategies, including using a tent chaotic map for population initialization to enhance diversity and replacing the traditional step size adjustment with a nonlinear perturbation factor to improve global search capability. Furthermore, an orthogonal refracted opposition-based learning strategy enhances solution quality and search efficiency by leveraging the dominant dimensional information. Additionally, performance comparisons with eight advanced algorithms on the CEC2017 test set (30-dimensional, 50-dimensional, 100-dimensional) are conducted, and the ECOA's effectiveness is validated through Wilcoxon rank-sum and Friedman mean rank tests. In practical robotic arm trajectory planning experiments, ECOA demonstrated superior performance, reducing costs by 15% compared to the best competing algorithm and 10% over the original COA, with significantly lower variability. This demonstrates improved solution quality, robustness, and convergence stability. The study successfully introduces novel population initialization and search strategies for improvement, as well as practical verification in solving the robotic arm path problem. The results confirm the potential of ECOA to address optimization challenges in various engineering applications. [ABSTRACT FROM AUTHOR]

Invasive species have been drivers of biodiversity loss and functional changes in aquatic ecosystems, including in protected areas. Therefore, monitoring population invasion dynamics and biological traits is fundamental to better understand their ecological and economic impacts and for management actions development. We followed signal crayfish (Pacifastacus leniusculus) invasion in Rabaçal River upper reach at Montesinho Natural Park, Portugal. We collected information on the spread and biological traits (abundance, size, weight, physical condition, sex ratio, and aggressiveness) to assess differences between invasion core and front areas and among years. Signal crayfish population remained restricted since first reports in 2013 in the invasion core until 2017. After 2019, signal crayfish population has been spreading downstream, decreasing abundance at invasion core but increasing at invasion front. Significant higher number of crayfish with claw loss indicate potential higher signs of aggressiveness in the invasion front. Results also demonstrate a significant dominance of females although sex ratio is closer to 1:1 at the invasion front. Overall, results indicate signal crayfish is spreading and increasing their abundance at Rabaçal River highlighting the need for immediate management actions to hold dispersion and mitigate possible impacts. [ABSTRACT FROM AUTHOR]

Northern Crayfish, Faxonius virilis, displays various strategies that allow them to survive extended periods of oxygen deprivation. However, certain epigenetic adaptations that these crayfish use have not been studied in detail, and the role of specific mechanisms used such as histone modifications remain unknown. Epigenetic studies offer a new perspective on how crayfish can regulate gene expression to redirect energy to essential functions needed for survival. This study investigates the regulation of histone modifications of proteins including acetylation and deacetylation in F. virilis in response to 20-h anoxia exposure. These histone modifications were studied via analysis of writer, reader, and eraser proteins such as lysine acetyltransferases (KATs), bromodomain proteins (BRDs), histone deacetylases (HDAC), and sirtuin proteins (SIRTs). Significant upregulation was seen in one histone protein and one lysine acetyltransferase: H3K14Ac and KAT2A. These proteins are known to be regulated by BRD2; a protein that specifically reads and targets H3K14Ac. In response to anoxia, a larger number of histone deacetylases and sirtuin proteins were upregulated in comparison to lysine acetyltransferases suggesting a focus on suppression of gene expression. The histone deacetylases and sirtuin proteins with significant upregulation were HDAC2, HDAC3, SIRT2, SIRT3, and SIRT6. These proteins have also all been implicated in DNA damage regulation which further suggests that crayfish focus limited energy on ensuring cell survival. This study provides an understanding of how histone acetylation and deacetylation are regulated in crayfish as a component of metabolic rate suppression under anoxia. [ABSTRACT FROM AUTHOR]

Objective To understand the various metal elements content and distribution in crayfish sold in Deyang, and to initial determine the harm of hazardous metallic elements to residents in Deyang. Methods A total of 102 samples were collected in Deyang using a stratified random sampling approach, the samples was digested by microwave digestion, 17 mineral elements and 7 harmful metal elements were detected using inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectrometry (ICP- MS). Results Mineral elements in all parts of the crayfish were detected and the content varies, in terms of total minerals, crayfish brain > crayfish intestine > crayfish gills > crayfish meat > crayfish hepatopancreas. For harmful metals, there was no exceedance in crayfish meat, As, Cu, Cd in crayfish hepatopancreas exceeded the standard rate of 97.0%, 2.97%, 27.7%, Hg, Pb, Cr did not exceed the standard, As, Cu, Pb, Cr and Al were all exceeded the standard in the non-edible parts by 2.17% to 100%. The enrichment pattern of all metal elements in crayfish in Deyang and Hubei was consistent, but the contents varied. In different sampling sessions, none of the harmful metal elements in crayfish meat exceeded the standard; As, Cu, Cd in crayfish hepatopancreas exceeded the standard rate of 2.8% -97%, and the rest of the elements did not exceed the standard. In different growth stages, except for As, there was no significant difference in the accumulation of hazardous metal elements between green and red crayfish. Conclusion Crayfish have a high mineral content and abundant nutrients, and local residents in Deyan City have a lower risk of heavy metal hazards in their daily intake of crayfish. [ABSTRACT FROM AUTHOR]

Industrial robotic arms are often subject to significant end-effector pose deviations from the target position due to the combined effects of nonlinear deformations such as link flexibility, joint compliance, and end-effector load. To address this issue, a study was conducted on the analysis and compensation of end-position errors in a six-degree-of-freedom robotic arm. The kinematic model of the robotic arm was established using the Denavit–Hartenberg (DH) parameter method, and a rigid–flexible coupled virtual prototype model was developed using ANSYS and ADAMS. Kinematic simulations were performed on the virtual prototype to analyze the variation in end-effector position errors under rigid–flexible coupling conditions. To achieve error compensation, an approach based on an Enhanced Crayfish Optimization Algorithm (ECOA) optimizing a BP neural network was proposed to compensate for position errors. An experimental platform was constructed for error measurement and validation. The experimental results demonstrated that the positioning accuracy after compensation improves by 75.77%, fully validating the effectiveness and reliability of the proposed method for compensating flexible errors. [ABSTRACT FROM AUTHOR]

Simple Summary: Freshwater crayfish are important organisms in terms of their ecological role and reputation as a delicacy and food source with cultural significance. In Russia, crayfish are abundant in water bodies and are extensively harvested. In this review, we summarize recent information on the biology of the main species, as well as aquaculture practices which are being developed to meet the growing demand for high-quality products. We discuss the main problems in the industry and provide further directions for the development of crayfish farming in Russia. Natural populations of crayfish in Europe have experienced significant declines due to the spread of crayfish plague, overfishing, competition with invasive crayfish species, and habitat degradation. Consequently, crayfish farming has gained importance in meeting the increasing demand for crayfish products. Although Russia boasts abundant water resources, the development of crayfish aquaculture remains nascent. In this review, we consolidate recent studies by Russian researchers that focus on various aspects of crayfish cultivation. Extensive cultivation in open ponds is the most suitable method, owing to its accessibility and lower costs; however, it necessitates suitable environmental conditions within the water bodies. The production cycle encompasses pond preparation, stocking, exploration, restoration, and monitoring. Controlled cultivation of egg-bearing females is essential for producing high-quality seedstock for subsequent rearing. Experimental evidence suggests that crayfish exhibit high adaptability to artificial conditions, with formulated diets comprising artificial feeds for sturgeon and powdered dried beef by-products demonstrating promising results in terms of growth performance. Plastic tangled threads and mink shelters are recommended to reduce cannibalism. Short-term grow-out of juvenile crayfish can yield a profit margin of 17%, while a complete two-year production cycle is projected to achieve financial break-even over three years. The primary challenges confronting the industry include disease management, cannibalism, the need for skilled technical personnel, and insufficient financial and policy support. [ABSTRACT FROM AUTHOR]

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The quality of frozen crayfish (Procambarus clarkii) is challenged by freeze–thaw (FT) cycles during storage. The effect of freezing methods on the quality of crayfish during FT cycles was investigated by comparing physicochemical properties, microstructure, and myofibrillar protein (MPs) properties. Three methods were used for crayfish freezing, including air convective freezing (AF) at −20 °C and −50 °C, as well as liquid nitrogen freezing (LNF) at −80 °C. The frozen crayfish were thawed at 4 °C after 45 d of frozen storage as 1 FT cycle. After 5 FT cycles, the water holding capacity of LNF crayfish (70.8%) was significantly (p < 0.05) higher than that of −20 °C AF crayfish (60.6%) and −50 °C AF crayfish (63.5%). The drip loss of LNF crayfish (7.83%) was significantly lower than that of AF crayfish. Moreover, LNF maintained the gel strength and the thermal stability of MPs from crayfish with higher gel storage modulus and enthalpy. These results demonstrated that LNF minimized the formation of large ice crystals, preserving the structural integrity of muscle and the properties of MPs, thereby maintaining crayfish quality. This study investigated the effect of LNF in preserving crayfish quality during FT cycles, providing valuable insights for reducing the quality degradation of aquatic products during storage and transportation. [ABSTRACT FROM AUTHOR]

Among the nicotinoid insecticides, imidacloprid (IMI) may affect non-target invertebrates like aquatic crustaceans by entering the aquatic environment through rainfall. Nevertheless, there are not sufficient studies on the toxicity mechanism of IMI in crayfish. Here, we investigated the effects of IMI on oxidative stress, osmoregulatory, and neurotoxicity biomarkers. The 96-hour lethal concentration value (96 h-LC50) of IMI was determined to be 0.932 mg AI L−1. Four concentrations of IMI (0.932, 0.466, 0.233 and 0.117 mg AI L−1) were applied to crayfish for 96 h. Na+/K+-ATPase, Mg2+-ATPase, Ca2+-ATPase, and total ATPase activities had almost significantly concentration-related inhibition in both gill and muscle tissues (p < 0.05). Compare with control in hepatopancreas, the activities of GST, SOD and GPx were increased, while the activities of AChE, CES and GR were decreased (p < 0.05). As non-enzymatic parameters, a statistically significant (p < 0.05) increase in MDA levels and a decrease in GSH levels were observed in the hepatopancreas compared to the control group, which was not related to the concentration. In conclusion, it can be said that the study's biomarkers are highly helpful and that commercially consumed crayfish are a significant non-target organism in the assessment of IMI toxicity. [ABSTRACT FROM AUTHOR]

This article proposes a conservation voltage reduction (CVR), Var optimization (VO), and network reconfiguration (NR)-based energy management technique. The main focus of this article is to maximize substation demand reduction, annual cost savings, voltage improvement, and node voltage optimization under different loading patterns. The proposed energy management method has been solved using 2 different optimization methods. Optimal tap setting of on-load tap changer (OLTC) while applying CVR and VO has been performed using crayfish optimization algorithm (COA), whereas NR has been carried out using binary particle swarm optimization (BPSO). The proposed scheme has been tested on the IEEE-69 node system, assessing various cases, including no control, with CVR alone, with CVR and VO, with CVR and NR, and with CVR, VO, and NR. Simulation results show that the combined operation of CVR, VO, and NR leads to improved outcomes in reducing substation demand and achieving cost savings. Furthermore, the proposed scheme has been tested for different network loading conditions, and improved results are obtained compared to other cases. Additionally, the efficacy of the COA has been compared to existing optimization algorithms under higher loading patterns. The COA algorithm converges to a minimal value of 0.2160 promptly in 22.47 s. [ABSTRACT FROM AUTHOR]

Crayfish are emerging as model organisms for various disciplines. Moreover, decapod crustaceans also exhibit pain‐like reactions and heightened anxiety when exposed to harmful stimuli, leading to short‐term or persistent behavioral shifts. Awareness of decapod crustacean sentience and thus, suffering calls for refinement of current laboratory protocols. This study aims to enhance the standard methodology for injecting substances into crayfish by minimizing stress‐inducing manipulation. We examined the impacts of various administration routes on the persistence of injected chemicals in marbled crayfish, its excretion, and animal survival. Fluorescein dye was used as a visual marker. It was administered via three alternative injection routes—intracoelomic (IC), intrapericardial administration through areola (IP‐A), and intrapericardial administration through arthrodial membrane (IP‐AM). Continuous video observations were made for a 4‐h period under UV light, followed by intermittent observations at 12‐h intervals over 48 h. The highest mortality (20%) was observed in IP‐A administration. The IP‐A method also provided the fastest systemic distribution of the dye in the body. Results indicated visibly higher urination frequency in IP‐AM compared to IP‐A. IC mirrored IP‐AM outcomes without any observed mortality. We conclude that IC administration proved superior to intrapericardial methods, offering the least harmful but effective approach for crayfish injections. Summary: Results indicated that the administration route matters in the research of model crayfish. The IC‐administered crayfish performed better in terms of mortality, urine release, and retention time. The present study provided data beneficial for crayfish use in experimental works by identifying a proper administration route to reduce the suffering/stress to the animals without compromising the efficacy of the injected substance. [ABSTRACT FROM AUTHOR]

This study presents an updated fish checklist of the Sultan Idris Shah Forestry Education Centre (SISFEC), Puchong, Selangor, Malaysia. Fish samples were collected using gill nets, cast nets, scoop nets, baited lines, and electrofishers at eight sites within SISFEC, including Rasau River, Bohol River, and several lentic water bodies. There are 29 fish species, representing 13 families of freshwater fish, with the family Danionidae (six species) dominating the list. Of the 29 species recorded, six were non-native, including Oreochromis niloticus, Barbonymus gonionotus, Puntigrus tetrazona, Pterygoplichthys disjunctivus, Oreochromis sp. (red), and Poecilia reticulata. In addition to the non-native species recorded, the Australian red claw crayfish, a non-native invasive invertebrate, was also encountered. Despite the increase in recorded native species compared to past reports, potential threats from invasive species remain a concern. Regular monitoring and strict regulation are recommended to ensure the conservation and sustainable use of SISFEC's aquatic biodiversity. [ABSTRACT FROM AUTHOR]

Crayfish plague is considered the most important crayfish disease globally. It is caused by the fungus-like agent, Aphanomyces astaci. This study aimed to identify and determine the prevalence of A. astaci using PCR in narrow-clawed crayfish (Pontastacus leptodactylus) populations from across Türkiye.

Abstract Background Haff disease is a condition that has emerged in China in recent years, primarily associated with the consumption of crayfish. Despite its increasing incidence, the exact cause of Haff disease remains unknown, prompting further investigation into its potential triggers and risk factors. The purpose of this system review is to investigate and summarize the current understanding of Haff disease and provide insights into the etiology and pathogenesis of Haff disease by collecting and analyzing data from a large number of patients. Method Systematic searches were conducted in PubMed, CNKI, and Wanfang Databases to investigate and summarize Haff disease by crayfish consumption in China over recent years. The search included observational studies published up to May 1, 2024. Result This review collected data from 1437 patients and conducted a comprehensive analysis of symptoms. In-depth examinations of patient symptoms revealed that nearly all patients exhibited abnormally elevated serum creatine kinase levels and muscular pain, while some also experienced changes in urine color, abdominal discomfort, and chest pain. Risk factors associated with Haff disease from crayfish consumption included high crayfish consumption, alcohol use, the consumption of specific crayfish organs such as the head, liver, and pancreas, and the consumption of wild crayfish. Conclusion Haff disease is indeed related to the consumption of crayfish, which may be due to the presence of an unknown heat stable toxin in crayfish. During the research process, many risk factors were identified, and it is recommended that people who consume crayfish pay attention to these risk factors and take appropriate preventive measures to minimize the risk of illness.

In order to explore the accumulation of heavy metals in crayfish cooking juice and its effect on the level of heavy metals in edible parts (crayfish tail) under different cooking methods. The levels of nine heavy metals As, Ba, Cd, Cr, Cu, Hg, Mn, Ni, and Pb in crayfish tails and cooking juice at different stages were detected by inductively coupled plasma spectrometer (ICP-OES) under three different cooking methods: Boiling, frying and seasoning. The single factor pollution index was used to judge the heavy metal pollution degree of crayfish tails, and the influence of heavy metal accumulation in cooking juice on crayfish tails was explored by correlation analysis. The results showed that high concentrations of Mn and Cu were observed in the crayfish boiling juice, the concentrations of toxic elements As and Cr increased by 88.8% and 80.7% in the crayfish frying oil, respectively. Furthermore, the concentration of Mn in the crayfish seasoning sauce increased by about 5.4 times compared with the control. With the increase of complexity of cooking method, the level of most heavy metals in the cooking juice would accumulate gradually with the processing process. The correlation analysis revealed that there was a significant positive correlation between heavy metals in the cooking juice and certain metals in crayfish tails (P

In this paper, the effects of rice and shrimp farming on rice yield, water quality and farmer income were analyzed. An econometric model based on simplified form of crop yield was used to compare the differences and impact degree of rice and shrimp farming data in Jingzhou city from 2018 to 2020. The results showed that rice shrimp culture could significantly improve rice yield and farmers’ income, but had some effects on water quality, and the degree of impact increased with the increase of crayfish density. It is suggested that the government should strengthen the technical guidance and supervision of rice and shrimp farming, and promote the optimized cultivation mode of rice and shrimp rotational cultivation. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to investigate the optimal conditions for solid-state fer‐ mentation in order to enhance pectinase production by Paenibacillus sp. C21, which was isolated from the intestinal tract of crayfish. Based on the results obtained from a single factor experiment, a response surface design approach was employed to optimize the solid-state fermentation process for pectinase pro‐ duction. The findings revealed that under the following conditions: culture time of 4 days, culture tem‐ perature of 32 ℃, inoculation amount of 8%, loading amount of 40 g/250 mL, and water/material ratio of 2.3∶1; the highest pectinase activity reached 482.65 U/g wet basis. This value represented an increase of 34.67% compared to the initial fermentation process with an activity level of 358.39 U/g wet basis. These results demonstrate that Paenibacillus sp. C21 exhibits significant potential for high pectinase production and can be utilized as probiotics in Procambarus clarkii feed formulations while also offering opportuni‐ ties for developing efficient microecological preparations. [ABSTRACT FROM AUTHOR]

Simple Summary: In the present work, we adopted morphometry to investigate the presence of two different morphotypes in the highly invasive crustacean Procambarus clarkii, the Louisiana crayfish, caught in an isolated Mediterranean population so far never investigated. We distinguished two morphotypes: in the "form I", or the reproductive form, crayfish exhibit enhanced secondary sexual features, such as gonopods and chelae; in the "form II", animals are equipped with smaller chelae and poorly calcified gonopods. We further estimated by morphometry the size at onset of maturity (SOM) in males of the Louisiana crayfish, between 35.0 and 37.1 mm of carapace length. Morphometric analysis was preceded by molecular techniques used for a correct taxonomic attribution of the crayfish here analyzed. Furthermore, molecular analysis was also applied to detect the presence of the pathogenic fungus, Aphanomyces astaci, in the tissues of crayfish. Our study is useful to enrich the biological knowledge of this highly invasive crustacean, whose spread is severely endangering freshwater ecosystems. We adopted a morphometric approach to provide statistical support for the description of two different morphotypes (I, reproductive, II, non-reproductive) firstly observed in Procambarus clarkii specimens caught in a population from Sardinia Island (western Mediterranean). The morphometric study was preceded by molecular taxonomic identification using the mitochondrial Cytochrome C Oxidase subunit I (COI) gene. The presence or absence of the pathogen Aphanomyces astaci, responsible for the plague, was also investigated using the ribosomal Internal Transcribed Spacer (ITS) marker. The estimation of the size at onset of maturity (SOM) was further performed in males. Finally, the population structure was examined. Our results confirmed the entirety of the individuals as P. clarkii, and the absence of the pathogen A. astaci. Morphological analysis revealed a significant correlation between chela and carapace lengths, while intra- and inter-sexual dimorphism in the chela length confirmed the occurrence of the two morphotypes. The SOM in males was established between 35.0 and 37.1 mm carapace length. Finally, the size-population structure showed a Gaussian distribution. The recognition of the two distinct morphotypes in the crayfish could be useful as an additional tool not only to identify the reproductive period of this invasive crustacean but also to enrich the guidelines for the correct taxonomic identification of the species. [ABSTRACT FROM AUTHOR]

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

The objective of the present study was to investigate the antimicrobial properties of a chitosan-based cream. To achieve this, the antimicrobial effects of a cream enriched with chitosan were compared with those of a control group. Chitosan, sourced from crayfish obtained frozen from Eğirdir Lake, Eğirdir, Isparta, served as the primary material. The study involved a comparison between control (F1) and treatment (F2) groups. While both cream formulations exhibited bacterial inhibition, only the F1 formulation demonstrated a significant reduction in viable microorganisms for C. albicans. The cytotoxicity assessment revealed a concentration-dependent increase in the cytotoxic effects of the samples. Notably, the F1 formulation exhibited higher toxicity to healthy cells compared to the F2 formulation. In conclusion, further investigation is necessary to understand the mechanisms underlying their cytotoxic effects and to optimize their formulations to enhance biocompatibility. Moreover, the chitosan-based cream developed in this study demonstrated notable antimicrobial efficacy against the tested bacteria. [ABSTRACT FROM AUTHOR]

For acoustically signalling animals, the rate of signal degradation is critical for successful communication. Degradation is heavily influenced by habitat characteristics, with sound degrading more rapidly in the presence of environmental obstacles (e.g. vegetation). Land management strategies such as prescribed burns eliminate obstacles and should therefore lead to more efficient sound transmission. Crawfish frogs (Rana areolata) produce long-distance advertisement calls for breeding. Habitats surrounding crawfish frog breeding ponds vary in vegetative density, and prairies surrounding breeding habitat often undergo controlled burns prior to the breeding season. We hypothesised that R. areolata advertisement calls would transmit more efficiently in post-burned prairies compared to other more vegetated habitats. To test this hypothesis, we conducted a sound transmission playback experiment, broadcasting crawfish frog calls in three habitats: forest, prairie, and post-burned prairie. We compared sound degradation measures between habitat types and across distances. We found that crawfish frog calls experienced up to 6.8 dB less excess attenuation in post-burned habitats relative to other habitat types, and that in general, prairie habitats had better sound transmission than forest. These results indicate that land management and habitat structure have consequences for acoustic communication, and may also influence the findings of frog call detection surveys. [ABSTRACT FROM AUTHOR]

Wildlife diseases figure prominently among the main causes of biodiversity loss worldwide. Especially fungal and fungus-like pathogens are on the rise, wreaking havoc across the tree of life by threatening species persistence and destabilizing ecosystems. A worrisome example are freshwater crayfish species in Eurasia and Oceania, facing the dual challenge of introduced competitive crayfish species and an introduced water mold (Aphanomyces astaci) causing crayfish plague. A. astaci locally extinguishes susceptible native crayfish populations, while non-native individuals (mostly from North America) remain largely unaffected. Despite its significant impact and its ∼150 years of presence in Europe, studies and disease management recommendations for crayfish plague that are firmly rooted in epidemiological theory are scarce. Here, we present a practical eco-epidemiological framework to understand how multi-species crayfish communities react to crayfish plague introductions. The framework is based on the observation that the dynamics of crayfish communities are mainly determined by life-history characteristics, within- and among-species competition, effects of generalist predators (including fishing), and host-pathogen interactions. From this ecological and epidemiological context, we derive fundamental epidemiological metrics, single-host species and community-level basic reproduction numbers (R0). We investigate how host species densities affect the likelihood of a disease outbreak in a crayfish community, and we demonstrate that a community's R0 value is simply the sum of the community's single-host species R0 values, adjusted for competition and predation. We further demonstrate how R0 can be used to guide preventative and mitigation actions for crayfish communities. For example, we show how R0 expressions – even without a detailed parametrization – can be used to construct regional risk rankings for different crayfish communities, for an effective allocation of resources to local conservation plans. Our eco-epidemiological framework will also be of interest to the management of other aquatic host-pathogen systems with water-borne pathogen transmission as the main route of pathogen spread. KEY POLICY HIGHLIGHTS: Fungal and fungus-like pathogens are on the rise globally and are taking a heavy toll on biodiversity, including crayfish species in many parts of the world. To aid management of native crayfish species confronted with highly competitive introduced crayfish and crayfish plague, we present and discuss a flexible eco-epidemiological framework. The framework – and derived simple results from it – offers a sound and holistic basis for the planning and implementation of mitigation actions, for crayfish communities and other freshwater species affected by fungal pathogens with a mainly water-borne transmission. [ABSTRACT FROM AUTHOR]

To investigate the effects of temperature stress on metabolic and digestive enzyme activities of Procambarus clarkii, the test species was transferred from 20°C (control group) to 10°C and 30°C, and samples were collected at 0, 3, 6, 12, 24, and 48h. The activities of pyruvate kinase (PK), hexokinase (HK) and hosphoenolpyruvate carboxykinase (PEPCK) in muscle and hepatopancreas of Procambarus clarkii was determined. The changes in a-amylase (a-AMY) and lipase (LPS) activity in intestinal and hepatopancreas were also examined. The results showed that the activities of digestive and metabolic enzymes in Procambarus clarkii were significantly affected by extreme water temperature (P<0.05). During the whole experimentation period, PK, HK, and PEPCK activities in the low-temperature group (10°C) were lower than those in the control group (20°C) (P < 0.05). Meanwhile, LPS and a-AMY activities in the low-temperature group (10°C) were also significantly lower than those in the control group (20°C) (P < 0.05). In the high-temperature group (30°C), the activities of PK, HK, and PEPCK metabolic enzymes in muscle and hepatopancreas decreased first. Then they increased, and their activity levels were significantly lower than those in the control group (P<0.05). At the same time, the activities of LPS and a-AMY digestive enzymes in the intestines and hepatopancreas were significantly lower than those in the control group(P<0.05). In summary, this study examined the impact of temperature stress on the metabolic and digestive enzyme activities in Procambarus clarkii, shedding light on its self-regulation mechanisms in response to temperature fluctuations. The findings provide a scientific foundation for understanding the species' adaptation to environmental changes. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the effects of different feeding rates on the growth, muscle composition, intestinal digestive enzyme activities, and intestinal microbiota composition of juvenile crayfish (Procambarus clarkii). A total of 240 crayfish with an initial body weight of 8.33±0.50 g were randomly distributed into five groups, and each group had three replicates. The five groups corresponded to five different feeding rates of 2%, 4%, 6%, 8%, and 10% body weight per day (BW/day). The feeding trial lasted for six weeks. The results showed that the final body weight (FBW), weight gain rate (WGR), and specific growth rate (SGR) first increased when the feed rate increased from 2% to 6 % (P<0.05) and then showed a decreased trend with the further increase of the feeding rate, but no significant differences were observed. The feed conversion ratio (FCR) increased with a rise in feeding rate, which reached a peak at the feeding rate of 10% (P<0.05). The survival rate (SR), hepatosomatic index (HSI), and condition factor (CF) were unaffected by the feeding rates (P>0.05). The moisture, crude protein, crude fat, and ash contents of crayfish muscle remained unchanged among all feeding rate groups. Intestinal activities of lipase and amylase increase with the feeding rate (up to 6%) increasing (P<0.05). The ACE and Chao indices in the groups fed at 2% of feeding rate were significantly lower than those at a feeding rate of 10% (P<0.05). The relative abundance of Firmicutes in the groups fed at feeding rates of 4%, 6%, and 8% was higher than that in other groups (P<0.05), Citrobacter in the group fed at feeding rate of 6% was lower than that in different groups (P<0.05). The intestinal microbiota primarily functions in connection to amino acid, carbohydrate, and vitamin metabolism. Therefore, the optimum feeding rate could be 6.0% of the feeding rate of juvenile P. clarkii. [ABSTRACT FROM AUTHOR]

In this preliminary study, we measured and compared the effectiveness of electrofishing and kick-seining sampling methods for crayfishes from 4 headwaters streams on the Domain of the University of the South. The University of the South is located on the southern Cumberland Plateau ecoregion in Sewanee, TN. Specifically, we examined how many individuals were captured between gears, and carapace-length differences between capture methods during March--April 2024. Focal species were Cambarus sphenoides (Triangleclaw Crayfish) and Faxonius placidus (Bigclaw Crayfish). Four times as many crayfish were captured on average with the electrofishing method (13.5 ± 4.1 crayfish) compared with the kick-seining method (3.0 ± 1.1 crayfish) across all 4 streams. Captured crayfish were of similar sizes using both methods. The higher catch rate from electrofishing compared to kick seining demonstrates that electrofishing is the best sampling method for headwater streams tested on the southern Cumberland Plateau for Triangleclaw Crayfish and Bigclaw Crayfish. [ABSTRACT FROM AUTHOR]

Sustainability of natural stocks of crayfish is critical because of their economic and ecological importance. Crayfish (Pontastacus leptodactylus), one of the most important species in Turkish inland fisheries, has been facing serious threats recently. One threat the species faces is high landed bycatch of undersized crayfish because of selective fishing gear, such as fyke nets. We estimated size‐selectivity of sorting grids with various bar spacings for crayfish to reduce bycatch. Six bar spacings (15.0, 17.5, 20.0, 22.5, 25.0, and 30.0 mm) were tested alongside commercial crayfish fyke nets. Mean selectivity (L50) (±95% CI) was 6.90 (6.63–6.99) cm for 15.0 mm bar spacing, 7.52 (7.16–8.02) cm for 17.5 mm, 8.52 (8.32–8.71) cm for 20.0 mm, 9.70 (9.28–9.90) cm for 22.5, 10.75 (10.34–11.17) cm for 25.0 mm, 11.80 (11.31–12.24) cm for 30.0 mm, and 8.79 (8.05–9.29) cm for commercial fyke nets. The proportion of undersized specimens caught be reduced from 32.27% for commercial fyke nets to as low as 2.46% by using sorting grids. The codend of 22.5 mm bar spacing was more selective, with significantly lower discard rates, and more effective for individuals above the minimum conservation reference size than commercial fyke nets. [ABSTRACT FROM AUTHOR]

Crayfish (Cherax quadricarinatus) is an economically valuable fishery product but its freshness and nutritional content decreases quickly during storage. To observe the freshness level of crayfish, a smart label was developed with the addition of color indicators made from red dragon fruit peel extracts (RDFPE). The purpose of this study was to apply RDFPE as an indicator of colorimetric smart labels in monitoring the freshness of crayfish. There were four levels of RDFPE, namely 0, 15, 20, and 25%. When different levels of pH were used, RDFPE colors changed. Optimization using Design Expert (V13) software indicated that the use of 15% (v/v) of RDFPE in PVA and chitosan film was the best treatment for preparing a colorimetric smart label. This smart film had a thickness of 101 mm, tensile strength of 4.4 MPa, elongation of 118%, and water vapor permeability of 4.3×10-10 g s-1 m-1 Pa-1. The pH, total volatile basic (TVB), and total plate count (TPC) values of crayfish rose along with storage time and they had a strong correlation with the ΔE value of the smart label. This study concluded that the addition of RDFPE could be used as a color indicator to fabricate colorimetric smart labels for monitoring the freshness of packaged crayfish. [ABSTRACT FROM AUTHOR]

Background and Aim: The effects of phycocyanin (PC) on pigmentation have been extensively studied in fish; however, its specific impact on crustaceans, particularly Procambarus clarkii, remains underexplored. This study aimed to evaluate the impact of PCs extracted from Arthrospira platensis BUUC1503 on the color enhancement of P. clarkii crayfish when added to food pellets. Materials and Methods: The following five dietary treatments were prepared: a control (without PC) and four experimental diets with PC supplementation at concentrations of 10, 50, 100, and 500 mg/kg. The stability of the pellets in water was ensured for 180 min. P. clarkii crayfish were fed these diets at 5% of their body weight daily for 10 weeks. Body weight and total length were measured. Color changes in P. clarkii were also assessed. After the experiments, we treated the samples according to Animal Welfare Technical Information No.16.8 Correct euthanasia of decapods. Results: Although PC supplementation did not significantly affect the yellowness (b* value) of P. clarkii, it significantly enhanced the redness (a* value) and lightness (L* value) pigmentation compared with the control. At week 10, crayfish fed a diet containing 100 mg/kg PC exhibited the highest L* value (36.51 ± 1.59) (p < 0.001). Diet with 500 mg/kg PCs had the highest a* value (26.96 ± 0.64) (p < 0.001). Crayfish fed 50, 100, or 500 mg/kg PC had the highest survival rate (100%). PCs appear to positively affect weight gain in P. clarkii crayfish during weeks 8, 9, and 10 (p = 0.013, 0.003, and 0.034, respectively). However, statistical analysis revealed no significant differences in length among the dietary treatments. Conclusion: PCs effectively weight-gain and enhance red pigment deposition in the epidermal layer of P. clarkii. Further investigation is warranted to elucidate the underlying mechanisms. [ABSTRACT FROM AUTHOR]

In this study, the length–weight relationships of Pontastacus leptodactylus, a freshwater crayfish species found in the Keban Dam Lake, were assessed using both conventional methods and artificial intelligence techniques. Throughout the research process, all biometric measurements of the crayfish were meticulously recorded, including TL, TW, and other biometric data. These measurements were analyzed using both the conventional length–weight relationship method and artificial neural networks. The results obtained using artificial neural networks and conventional methods were compared, and the analysis was based on MAPE and R2 performance criteria. The study showed that the ANNs method outperformed the conventional LWR method, showing more accurate results. The models employed to predict the length–weight relationships of the crayfish demonstrated high accuracy, and the Artificial Neural Networks method was identified as the most effective model. These results provide strong evidence that the ANNs method performs significantly better in predicting the LWRs of freshwater crayfish. [ABSTRACT FROM AUTHOR]

Long‐term studies depicting the multicontinental invasion trajectories of species are often constrained by the scarcity of documented records, especially for invertebrates. The red swamp crayfish, Procambarus clarkii (Decapoda: Cambaridae), stands out as an uncommon example of hypersuccessful invasive species with a well‐known invasion history at both regional and global levels. This allows for the use of its records to track distribution dynamics and bioclimatic preferences over time. Through multiple temporal comparisons, the global bioclimatic tendencies of the species have been explored over a period exceeding a century (1854–2023) using linear models with generalized least squares estimation and two‐sample t‐tests. This specific setup provides a rare focus on biological invasions at both broad temporal and spatial scales. The results highlight climatic trends in the invasion process of the species, including decreases in the values of bioclimatic variables associated with temperature and precipitation. This trend encompasses not only mean values but also both extreme (minimum and maximum) and is coupled with increases in elevation and aridity values in the areas with the presence of the species. The findings indicate that the species can engage in new ecological interactions and further affect range‐restricted species in climatic refuges once considered protected. These findings help anticipate changes in the species' invasion trajectory, suggesting possible expansions into colder, less humid climates and higher altitudes. This knowledge supports effective monitoring and early detection for management and conservation efforts. [ABSTRACT FROM AUTHOR]

Background: Cambaroides schrenckii is an endangered freshwater crayfish in China, belonging to the genus Cambaroides, that can act as a complementary host for paragonimus. The objective of this study was to examine the complete mitochondrial genome characteristics and their evolutionary relationships within the Astacidea. Methods: The analysis of gene rearrangements and evolutionary relationships was conducted through the sequencing of the mitochondrial genome of C. schrenckii. Results: C. schrenckii mitochondrial genome length was 15,572, comprising thirteen PCGs, two rRNAs, 22 tRNAs, and one d-loop region of C. schrenckii. The mitochondrial genome of C. schrenckii exhibits an A + T content of 69.61% and a G + C content of 30.39%. Among the thirteen PCGs, cytb, nad3, and nad6 have a start codon of ATT, while the other ten PCGs have ATC, ATA, and ATG start codons. All 22 tRNA genes displayed a typical cloverleaf secondary structure. Gene rearrangement analysis showed that seven gene arrangements were identified based on PCGs in the infraorder Astacidea, with type I being the most common. Conclusions: The relationship between the American Cambaridae is closer to Astacidae than the Asian Cambaridae. The present study provides a theoretical basis for further discussions of developmental relationships in the infraorder Astacidea. [ABSTRACT FROM AUTHOR]

In this study, the direct and indirect causal relationships among the length, weight, egg diameter, egg weight, and egg quantity of female Pontastacus leptodactylus were analyzed using a path analysis. A total of 79 egg-bearing female crayfish with a total weight (WT; 39.1 ± 16 g) and total length (TL; 109.6 ± 18.1 mm), were sampled from Eğirdir Lake, Türkiye, in 2022 and 2023. Significant direct effects were observed several traits, such as crayfish length and weight, weight and egg diameter, length and egg quantity, egg diameter and egg quantity, weight and egg quantity, length and egg weight, and egg quantity and egg weight (p<0.05). These relationships indicate that larger females tend to produce a higher number of eggs and have greater overall reproductive potential. In contrast, no significant relationships were found between length and egg diameter, weight and egg weight, and egg diameter and egg weight (p>0.05), suggesting that body size may not directly influence egg size in this species. Regarding indirect effects, crayfish length was found to significantly influence egg weight through egg quantity (p<0.05). This suggests that larger females indirectly affect egg weight by producing more eggs. Although the direct effect of egg diameter on egg weight was not significant (p>0.05), its indirect effect of egg diameter on egg weight through egg quantity was significant (p<0.05), indicating that egg diameter plays a role in reproductive output through its influence on egg numbers. The findings of this study contribute to a better understanding of the direct and indirect causal relationships between growth-related traits and egg-related traits in freshwater crayfish. These insights can be utilized in sustainable fisheries management and aquaculture practices by informing selective breeding programs to enhance reproductive success or guiding conservation strategies that protect larger females in natural populations. [ABSTRACT FROM AUTHOR]