Global invasion and biosecurity risk from the online trade in ornamental crayfish.

Trade in undomesticated ornamental animals has rapidly expanded beyond brick-and-mortar retail stores to now include growing numbers of internet marketplaces. The growing volume, diversity, and origins of invasive non-native species in trade challenge already weak national biosecurity policies. Despite widespread focus on vertebrates, many knowledge gaps exist regarding the online global trade of ornamental invertebrates. We conducted the first global assessment of the online trade in and associated invasion risk of freshwater crayfishes, which are increasingly popular aquarium animals. We systematically examined e-commerce marketplaces in multiple languages, scrapping information that included species identity, price, quantity, and shipping designation from each crayfish listing. Next, we combined geographic pathways of shipping associated with online trade (introduction risk) and environmental suitability modeling (establishment risk) to estimate global risk of non-native crayfish invasion risk. We identified hundreds of online marketplaces and thousands of sale listings in 33 countries (5 continents) involving 60 species and representing a selling value of ∼US$1.5 million. Invasion risk of non-native crayfish in trade was widespread, with geographic hotspots coinciding with both elevated opportunities for introduction (greater shipping offerings) and establishment. Precise characterization of the online species trade is fundamental to support new and reformed biosecurity policies, build industry partnerships, and design educational campaigns to prevent species invasions through trade. We found that the taxonomy, geography, and economics of the global online ornamental crayfish trade are vast and require greater attention.

Invasión global y riesgos de bioseguridad a partir del mercado virtual de langostinos de ornato Resumen El comercio de animales ornamentales silvestres se ha expandido rápidamente más allá de las tiendas minoristas para incluir un número creciente de tiendas en línea. El creciente volumen, diversidad y origen de las especies no nativas invasoras en el comercio suponen un reto para las ya débiles políticas nacionales de bioseguridad. A pesar de la gran atención que se presta a los vertebrados, existen muchos vacíos en el conocimiento sobre el comercio mundial en línea de invertebrados ornamentales. Realizamos la primera evaluación mundial del comercio virtual de langostinos de agua dulce, animales de ornato cada vez más populares, y el riesgo de invasión asociado. Analizamos sistemáticamente los mercados de comercio electrónico en varios idiomas, recopilando información que incluía la identidad de las especies, el precio, la cantidad y la designación de envío de cada listado de langostinos. Después combinamos las vías geográficas de envío asociadas al comercio en línea (riesgo de introducción) y los modelos de idoneidad ambiental (riesgo de establecimiento) para estimar el riesgo global de invasión de los langostinos no nativos. Identificamos cientos de mercados en línea y miles de listados de venta en 33 países (cinco continentes) que afectaban a 60 especies y representaban un valor de venta de ∼1.5 millones de dólares estadunidenses. El riesgo de invasión de langostinos no nativos en el comercio fue extenso, con puntos geográficos críticos que coincidían con elevadas oportunidades de introducción (mayores ofertas de envío) y de establecimiento. La caracterización precisa del comercio virtual de especies es fundamental para respaldar políticas de bioseguridad nuevas y reformadas, establecer alianzas con la industria y diseñar campañas educativas para prevenir las invasiones de especies a través del comercio. Descubrimos que la taxonomía, la geografía y la economía del comercio mundial en línea de langostinos de ornato es amplio y requiere mayor atención.

How to reduce fear in a snail: Take an aspirin, call me in the morning.

Aspirin (Acetylsalicylic acid, ASA), one of the widely used non-steroid anti-inflammatory drugs can easily end up in sewage effluents and thus it becomes necessary to investigate the effects of aspirin on behaviour of aquatic organisms. Previous studies in mammals have shown ASA to alter fear and anxiety-like behaviours. In the great pond snail Lymnaea stagnalis, ASA has been shown to block a 'sickness state' induced by lipopolysaccharide injection which upregulates immune and stress-related genes thus altering behavioural responses. In Lymnaea, eliciting physiological stress may enhance memory formation or block its retrieval depending on the stimulus type and intensity. Here we examine whether ASA will alter two forms of associative-learning memory in crayfish predator-experienced Lymnaea when ASA exposure accompanies predator-cue-induced stress during the learning procedure. The two trainings procedures are: 1) operant conditioning of aerial respiration; and 2) a higher form of learning, called configural learning, which here is dependent on evoking a fear response. We show here that ASA alone does not alter homeostatic aerial respiration, feeding behaviour or long-term memory (LTM) formation of operantly conditioned aerial respiration. However, ASA blocked the enhancement of LTM formation normally elicited by training snails in predator cue. ASA also blocked configural learning, which makes use of the fear response elicited by the predator cue. Thus, ASA alters how Lymnaea responds cognitively to predator detection.

Intraspecific variation in crayfish behavioral traits affects leaf litter breakdown in streams.

Although intraspecific trait variation is increasingly recognized as affecting ecosystem processes, few studies have examined the ecological significance of among-population variation in behavioral traits in natural ecosystems. In freshwater habitats, crayfish are consumers that can influence ecosystem structure (e.g., macroinvertebrate communities) and function (e.g., leaf litter breakdown). To test whether crayfish behavioral traits (activity, boldness, and foraging voracity) are major contributors of leaf litter breakdown rates in the field, we collected rusty crayfish (Faxonius rusticus) from eight streams across the midwestern USA and measured behaviors using laboratory assays. At the same streams, we measured breakdown rates of leaf packs that were accessible or inaccessible to crayfish. Our results provide evidence that among-population variation in crayfish boldness and foraging voracity was a strong predictor of leaf litter breakdown rates, even after accounting for commonly appreciated environmental drivers (water temperature and human land use). Our results suggest that less bold rusty populations (i.e., emerged from shelter more slowly) had greater direct impacts on leaf litter breakdown than bold populations (P = 0.001, r2 = 0.85), potentially because leaf packs can be both a shelter and food resource to crayfish. Additionally, we found that foraging voracity was negatively related to breakdown rates in leaf packs that were inaccessible to crayfish (P = 0.025, r2 = 0.60), potentially due to a trophic cascade from crayfish preying on other invertebrates that consume leaf litter. Overall, our results add to the growing evidence that trait variation in animals may be important for understanding freshwater ecosystem functioning.

Effect of abamectin on osmoregulation in red swamp crayfish (Procambarus clarkii).

As a widely used pesticide, abamectin could be a threat to nontarget organisms. In this study, the toxic mechanism of abamectin on osmoregulation in Procambarus clarkii was explored for the first time. The results of this study showed that with increasing abamectin concentration, the membrane structures of gill filaments were damaged, with changes in ATPase activities, transporter contents, biogenic amine contents, and gene expression levels. The results of this study indicated that at 0.2 mg/L abamectin, ion diffusion could maintain osmoregulation. At 0.4 mg/L abamectin, passive transport was inhibited due to damage to the membrane structures of gill filaments, and active transport needed to be enhanced for osmoregulation. At 0.6 mg/L abamectin, the membrane structures of gill filaments were seriously damaged, and the expression level of osmoregulation-related genes decreased, but the organisms were still mobilizing various transporters, ATPases, and biogenic amines to address abamectin stress. This study provided a theoretical basis for further study of the effects of contaminations in aquatic environment on the health of crustaceans.

Correlated evolution of conspicuous colouration and burrowing in crayfish.

Conspicuous colours have fascinated biologists for centuries, leading to research on the evolution and functional significance of colour traits. In many cases, research suggests that conspicuous colours are adaptive and serve a function in sexual or aposematic signalling. In other cases, a lack of evidence for the adaptive value of conspicuous colours garners interest from biologists, such as when organisms that live underground and are rarely exposed to the surface are nevertheless colourful. Here, we use phylogenetic comparative methods to investigate colour evolution throughout freshwater crayfishes that vary in burrowing ability. Within the taxa we analysed, conspicuous colours have evolved independently over 50 times, and these colours are more common in semi-terrestrial crayfishes that construct extensive burrows. The intuitive but not evolutionarily justified assumption when presented with these results is to assume that these colours are adaptive. But contrary to this intuition, we discuss the hypothesis that colouration in crayfish is neutral. Supporting these ideas, the small population sizes and reduced gene flow within semi-terrestrial burrowing crayfishes may lead to the fixation of colour-phenotype mutations. Overall, our work brings into question the traditional view of animal colouration as a perfectly adapted phenotype.

Considerations for protein and amino acids in standardized reference diet for parthenogenetic marbled crayfish Procambarus virginalis model organism.

The concept of a standardized reference diet (SRD) is used in laboratory model organisms to ensure nutritional control between studies and laboratories. Although models using the genetically identical, all female parthenogenetic marbled crayfish (Procambarus virginalis) are growing in popularity, research into nutrition in this species still has many knowledge gaps. To fast track the development of a SRD in terms of protein and amino acids (SRDprotein) for this species, we first analyzed the composition of its body amino acids to determine the ideal protein concept (IPC) of indispensable amino acids in wild-caught P. virginalis (which had an unusually high preponderance of leucine and arginine). Then, we strategically evaluated three common clusters of types of fish feed: (1) ornamental fish feed (SER) fortified with a naturally occurring alga (Spirulina). This type of feed was protein-high in arginine and leucine (SER + SPI) that fulfils the species' IPC for iso-protein (~ 40%), iso-phosphorus (~ 0.8%) and near iso-energetic (~ 475 kcal 100 g-1); (2) freeze-dried live feed consisting of chironomid larvae (CHI) fortified with Spirulina (CHI + SPI) that fulfils the IPC for iso-protein (~ 46%), iso-phosphorus (~ 0.7%) and near iso-energetic (~ 405 kcal 100 g-1); and (3) a commercially standardized 'starter diet' for carnivorous fish larvae (FISH) and post-larval shrimps (SHRIMP) with iso-protein (~ 56%) and iso-phosphorus (~ 1.6%). A total of six diets, embracing a diverse range of proteinaceous feeds, were used in a 100-day ad libitum feeding and growth trial. The FISH group outperformed all the other groups (p < 0.05) and our exploratory multivariate analysis revealed an ideal demand of > 44% protein (tailored to deliver high arginine 3% and leucine 4%, followed by the usual lysine > 3.5% and methionine 1.2%) but also the lowest carbohydrate level (21%). For SRDprotein, our findings show that the FISH diet is ideal and suggest the possibilities of using a CHI + SPI diet for further optimization (more economic use of protein and phosphorus).

Longitudinal tracking of hemocyte populations in vivo indicates lineage relationships and supports neural progenitor identity in adult neurogenesis.

Adult neurogenesis, which takes place in both vertebrate and invertebrate species, is the process by which new neurons are born and integrated into existing functional neural circuits, long after embryonic development. Most studies in mammals suggest that self-renewing stem cells are the source of the new neurons, although the extent of self-renewal is a matter of debate. In contrast, research in the crayfish Procambarus clarkii has demonstrated that the neural progenitors producing adult-born neurons are capable of both self-renewing and consuming (non-self-renewing) divisions. However, self-renewing divisions are relatively rare, and therefore the production of adult-born neurons depends heavily on progenitors that are not replenishing themselves. Because the small pool of neural progenitors in the neurogenic niche is never exhausted throughout the long lives of these animals, we hypothesized that there must also be an extrinsic source of these cells. It was subsequently demonstrated that the neural progenitors originate in hemocytes (blood cells) produced by the immune system that travel in the circulation before ultimately integrating into niches where the neural lineage begins. The current study examines the developmental lineage of the three hemocyte types - hyaline (HC), semigranular (SGC) and granular (GC) cells - with the goal of understanding the origins of the progenitor cells that produce adult-born neurons. Longstanding qualitative metrics for hemocyte classification were validated quantitatively. Then, in a longitudinal study, proliferation markers were used to label the hemocytes in vivo, followed by sampling the circulating hemocyte population over the course of two months. Hemolymph samples were taken at intervals to track the frequencies of the different hemocyte types. These data reveal sequential peaks in the relative frequencies of HCs, SGCs and GCs, which were identified using qualitative and quantitative measures. These findings suggest that the three hemocyte types comprise a single cellular lineage that occurs in the circulation, with each type as a sequential progressive stage in hemocyte maturation beginning with HCs and ending with GCs. When combined with previously published data, this timeline provides additional evidence that HCs serve as the primary neural progenitor during adult neurogenesis in P. clarkii.

Population-specific responses to pollution exposure suggest local adaptation of invasive red swamp crayfish Procambarus clarkii along the Mediterranean French coastline.

Anthropogenic stressors can have an impact in a broad range of physiological processes and can be a major selective force leading to rapid evolution and local population adaptation. In this study, three populations of the invasive crayfish Procambarus clarkii were investigated. They are geographically separated for at least 20 years, and live in different abiotic environments: a freshwater inland lake (Salagou lake) with no major anthropogenic influence and two other coastal wetlands regularly polluted by pesticides along the Mediterranean coast (Camargue region and Bages-Sigean lagoon). Collected adults were genetically characterized using the mitochondrial COI gene and haplotype frequencies were analyzed for genetic variability within and between populations. Results revealed a higher genetic diversity for these invasive populations than any previous report in France, with more than seven different haplotypes in a single population. The contrasting genetic diversity between the Camargue and the other two populations suggest different times and sources of introduction. To identify differences in key physiological responses between these populations, individuals from each population were maintained in controlled conditions. Data on oxygen consumption rates indicate that the Salagou and Bages-Sigean populations possess a high inter-individual variability compared to the Camargue population. The low individual variability of oxygen consumption and low genetic diversity suggest a specific local adaptation for the Camargue population. Population-specific responses were identified when individuals were exposed to a pesticide cocktail containing azoxystrobin and oxadiazon at sublethal concentrations. The Salagou population was the only one with altered hydro-osmotic balance due to pollutant exposure and a change in protease activity in the hepatopancreas. These results revealed different phenotypic responses suggesting local adaptations at the population level.

Inhibitory modulation of action potentials in crayfish motor axons by fluoxetine.

The goal of this report is to explore how K2P channels modulate axonal excitability by using the crayfish ventral superficial flexor preparation. This preparation allows for simultaneous recording of motor nerve extracellular action potentials (eAP) and intracellular excitatory junctional potential (EJP) from a muscle fiber. Previous pharmacological studies have demonstrated the presence of K2P-like channels in crayfish. Fluoxetine (50 µM) was used to block K2P channels in this study. The blocker caused a gradual decline, and eventually complete block, of motor axon action potentials. At an intermediate stage of the block, when the peak-to-peak amplitude of eAP decreased to ∼60%-80% of the control value, the amplitude of the initial positive component of eAP declined at a faster rate than that of the negative peak representing sodium influx. Furthermore, the second positive peak following this sodium influx, which corresponds to the after-hyperpolarizing phase of intracellularly recorded action potentials (iAP), became larger during the intermediate stage of eAP block. Finally, EJP recorded simultaneously with eAP showed no change in amplitude, but did show a significant increase in synaptic delay. These changes in eAP shape and EJP delay are interpreted as the consequence of depolarized resting membrane potential after K2P channel block. In addition to providing insights to possible functions of K2P channels in unmyelinated axons, results presented here also serve as an example of how changes in eAP shape contain information that can be used to infer alterations in intracellular events. This type of eAP-iAP cross-inference is valuable for gaining mechanistic insights here and may also be applicable to other model systems.

The impact of Roundup® Original DI on the hemolymph metabolism and gill and hepatopancreas oxidative balance of Parastacus promatensis (Crustacea, Decapoda, Parastacidae).

In Brazil, glyphosate is present in more than 130 commercial formulations, and its toxic effects have already been tested in different species to understand its impact on biota Decapod crustaceans are widely used as experimental models due to their biology, sensitivity to pollutants, ease of collection, and maintenance under laboratory conditions. We evaluated the changes in metabolism (hemolymph) and oxidative balance markers (gill and hepatopancreas) of a crayfish (Parastacus promatensis) after exposure to Roundup® (active ingredient: glyphosate). The crayfish were captured in the Garapiá stream within the Center for Research and Conservation of Nature Pró-Mata, Brazil. We collected adult animals outside (fall) and during (spring) the breeding season. The animals were transported in buckets with cooled and aerated water from the collection site to the aquatic animal maintenance room at the university. After acclimatization, the animals were exposed to different concentrations of glyphosate (0, 65, 260, 520, and 780 µg/L). The results showed a significant variation in the hemolymph glucose, lactate, and protein levels. We observed variations in the tissue antioxidant enzymatic activity after exposure to glyphosate. Finally, the increase in oxidative damage required a high energy demand from the animals to maintain their fitness, which makes them more vulnerable to stress factors added to the habitat.

Predation cues induce predator specific changes in olfactory neurons encoding defensive responses in agile frog tadpoles.

Although behavioural defensive responses have been recorded several times in both laboratory and natural habitats, their neural mechanisms have seldom been investigated. To explore how chemical, water-borne cues are conveyed to the forebrain and instruct behavioural responses in anuran larvae, we conditioned newly hatched agile frog tadpoles using predator olfactory cues, specifically either native odonate larvae or alien crayfish kairomones. We expected chronic treatments to influence the basal neuronal activity of the tadpoles' mitral cells and alter their sensory neuronal connections, thereby impacting information processing. Subsequently, these neurons were acutely perfused, and their responses were compared with the defensive behaviour of tadpoles previously conditioned and exposed to the same cues. Tadpoles conditioned with odonate cues differed in both passive and active cell properties compared to those exposed to water (controls) or crayfish cues. The observed upregulation of membrane conductance and increase in both the number of active synapses and receptor density at the postsynaptic site are believed to have enhanced their responsiveness to external stimuli. Odonate cues also affected the resting membrane potential and firing rate of mitral cells during electrophysiological patch-clamp recordings, suggesting a rearrangement of the repertoire of voltage-dependent conductances expressed in cell membranes. These recorded neural changes may modulate the induction of an action potential and transmission of information. Furthermore, the recording of neural activity indicated that the lack of defensive responses towards non-native predators is due to the non-recognition of their olfactory cues.

Gradual effects of gradient concentrations of perfluorooctane sulfonate on the antioxidant ability and gut microbiota of red claw crayfish (Cherax quadricarinatus).

Perfluorooctane sulfonate (PFOS) is a typical persistent organic pollutant that is characterized by environmental persistence, bioaccumulation, and toxicity. In this study, we investigated the gut microbial response of the red claw crayfish Cherax quadricarinatus after 28 days of exposure to 0 ng/L, 1 ng/L, 10 µg/L, or 10 mg/L of PFOS as a stressor. We measured oxidative stress-related enzyme activities and expression of molecules related to detoxification mechanisms to evaluate the toxic effects of PFOS. We found that PFOS disturbed microbial homeostasis in the gut of C. quadricarinatus, resulting in increased abundance of the pathogen Shewanella and decreased abundance of the beneficial bacterium Lactobacillus. The latter especially disturbed amino acid transport and carbohydrate transport. We also found that the activities of glutathione S-transferase and glutathione peroxidase were positively correlated with the expression levels of cytochrome P450 genes (GST1-1, GSTP, GSTK1, HPGDS, UGT5), which are products of PFOS-induced oxidative stress and play an antioxidant role in the body. The results of this study provided valuable ecotoxicological data to better understand the biological fate and effects of PFOS in C. quadricarinatus.

Variation in fine-scale water table depth drives abundance of a unique semi-terrestrial crayfish species.

With anthropogenic changes altering the environment and the subsequent decline of natural habitats, it can be challenging to predict essential habitats for elusive and difficult to study taxa. Primary burrowing crayfish are one such group due to the complexity in sampling their semi-terrestrial, subterranean habitat. Sampling burrows usually requires a labor-intensive, time-consuming excavation or trapping process. However, limited information on burrowing crayfish suggests that fine-scale habitat variation may drive burrowing crayfish habitat choice. This project aimed to evaluate the fine-scale habitat characteristics that influence burrowing crayfish presence and abundance at a large, restored-remnant grassland preserve in north-central Illinois. We documented burrow abundance and quadrat-specific habitat variables such as root biomass, canopy cover, apparent seasonal high-water table (water table) depth and dominant vegetation at sites with and without burrowing crayfish populations. Data was recorded at every quadrat and analyzed using generalized linear mixed models. A total of 21 models were created to determine what habitat variables affected burrow presence and abundance. We found that the water table depth was a significant driver of burrow presence and abundance. Root biomass and vegetation cover were not significant drivers, although they did show up in the final models, explaining the data. These findings demonstrate empirical support for previous observations from other burrowing crayfish research and demonstrate the influence of fine-scale habitat when modeling elusive taxa requirements.

Toxic mechanisms of nanoplastics exposure at environmental concentrations on juvenile red swamp crayfish (Procambarus clarkii): From multiple perspectives.

Nanoplastics pollution has emerged as a global issue due to its widespread potential toxicity. This study delved in to toxic effects of nanoplastics on juvenile P. clarkii and molecular mechanisms from perspectives of growth, biochemical, histopathological analysis and transcriptome level for the first time. The findings of this study indicated that nanoplastics of different concentrations have varying influence mechanisms on juvenile P. clarkii. Nanoplastics have inhibitory effects on growth of juvenile P. clarkii, can induce oxidative stress. The biochemical analysis and transcriptome results indicated that 10 mg/L nanoplastics can activate the antioxidant defense system and non-specific immune system in juvenile P. clarkii, and affect energy metabolism and oxidative phosphorylation. While 20 mg/L and 40 mg/L have a destructive influence on the immune function in juvenile P. clarkii, leading to lipid peroxidation and oxidative damage, and induce apoptosis, can affect ion transport and osmotic pressure regulation. The findings of this study can offer foundational data for delving further into impacts of nanoplastics on crustaceans and toxicity mechanism.

Evaluating micro-nano bubbles coupled with rice-crayfish co-culture systems: A field study promoting sustainable rice production intensification.

Traditional rice-fish symbiosis systems efficiently use soil and water resources but the adverse effects of prolonged flooding on the stability of rice growth can be mitigated. The feasibility and efficacy of injecting micro-nano bubbles (MNBs) in rice-crayfish co-cultures was investigated in a 22-hectare field experiment conducted over five months. This injection significantly enhanced the growth of both rice and crayfish, and increased total nitrogen and phosphorus levels in the soil, thereby augmenting fertility. Analysis of dissolved oxygen (DO), water temperature and gene expression (rice and crayfish) clarified that micro-nano bubbles (MNBs) foster an optimal environment for rice root respiration, whereas rice establishes an optimal temperature for crayfish, thereby enhancing their activity and growth. Comparative analyses of gene expression profiles and metabolic pathway enrichment revealed that the injection of MNBs diversifies soil microbial communities and intensifies biological processes, such as plant hormone signal transduction. This was in marked contrast to the situation in our controls, rice monoculture (R) and micro-nano bubbles rice monoculture (MNB-R). The combination of rice-fish symbiosis with MNBs led to a 26.8 % increase in rice production and to an estimated 35 % improvement in economic efficiency. Overall, this research introduces an innovative and environmentally sustainable method to boost rice yields, thereby enhancing food security and providing additional income for farmers.

Antibiotics in the rice-crayfish rotation pattern: Occurrence, prioritization, and resistance risk.

Antibiotics are extensively utilized in aquaculture to mitigate diseases and augment the productivity of aquatic commodities. However, to date, there have been no reports on the presence and associated risks of antibiotics in the emergent rice-crayfish rotation (RCR) system. This study investigated the occurrence, temporal dynamics, prioritization, sources, and potential for resistance development of 15 antibiotics within the RCR ecosystem. The findings revealed that during the crayfish breeding and rice planting periods, florfenicol (FFC) predominated in the RCR's surface water, with peak and average concentrations of 1219.70 ng/L and 57.43 ng/L, and 1280.70 ng/L and 52.60 ng/L, respectively. Meanwhile, enrofloxacin (ENX) was the primary antibiotic detected in RCR soil and its maximum and average concentrations were 624.73 ng/L and 69.02 ng/L in the crayfish breeding period, and 871.27 ng/L and 45.89 ng/L in the rice planting period. Throughout the adjustment period, antibiotic concentrations remained relatively stable in both phases. Notably, antibiotic levels in surface water and soil escalated during the crayfish breeding period and subsided during the rice planting period, with these fluctuations predominantly influenced by FFC and ENX. Source analysis indicated that the antibiotics in RCR predominantly originated from aquaculture activities, supplemented by water exchange processes. Utilizing the entropy utility function and a resistance development model, FFC, clarithromycin (CLR), and roxithromycin (ROX) in surface water, along with ENX, CLR, and ROX in soil, were identified as priority antibiotics. FFC, ENX, and ROX exhibited a medium risk for resistance development. Consequently, this study underscores the necessity to intensify antibiotic usage control during the crayfish breeding period in the RCR system to mitigate environmental risks.

Copper-Induced Chemosensory Impairment is Reversed by a Short Depuration Period in Northern Clearwater Crayfish (Faxonius propinquus).

Crayfish rely on their chemosensory system for many essential behaviours including finding food, finding mates, and to recognize individuals. Copper can impair chemosensation in crayfish at low concentrations; however, it is not clear if the effect is ameliorated once copper is removed. To better understand the effect of and recovery from copper exposure in crayfish, we exposed Northern clearwater crayfish (Faxonius propinquus) to 31.3 [Formula: see text] copper for 24 h and measured the response of the crayfish to a food cue. The crayfish were then placed into clean water to depurate for an 24 h. The results demonstrated that the crayfish did not respond to a food cue if they had been exposed to copper, but showed a full response after a 24 h recovery period without copper. Higher concentrations of copper have shown a much longer-term effect in rusty crayfish (Faxonius rustics), indicating there is a concentration where the copper is causing longer-term damage instead of just impairing chemosensation. These results highlight the fact that even though contaminants like copper can have profound effects at low concentrations, by removing the contaminants the effect can be ameliorated.

Effects of carbon source addition in rearing water on sediment characteristics, growth and health of cultured marron (Cherax cainii).

Carbon sources are considered as critical input for the health and immunity of aquatic animals. The present study investigated the impact of different carbon sources on water quality parameters, carbon to nitrogen (C/N) ratio and microbial community in sediments, and health responses of marron (Cherax cainii) under laboratory conditions. Following one week of acclimation, 120 marron were randomly assigned to 12 experimental tanks. There were four treatments including one untreated control and three groups with carbon addition to maintain a C/N ratio of 12 maintained in culture water. Carbon supplementation groups included corn flour (CBC12), molasses (MBC12) and wheat flour (WBC12). At the end of the 60-day trial, MBC12 resulted in the highest sediment C/N ratio, followed by CBC12. Weight gain and specific growth rate were higher in MBC12, compared to control. The protease activity in marron hepatopancreas, total haemocyte count and lysozyme activity in haemolymph were highest in MBC12. Analysis of 16S rRNA sequence data of tank sediments revealed increased bacterial alpha diversity in MBC12 and WBC12. Proteobacteria was the most abundant phylum in MBC12 (88.6%), followed by control (82.4%) and CBC12 (72.8%). Sphingobium and Novosphingobium were the most abundant genera in control and MBC12 groups, respectively. Higher Aeromonas abundance in CBC12 and Flavobacterium in WBC12 were observed. Overall results indicated that MBC12 led to improved water quality, retaining high C/N ratio and enriched the bacterial populations in sediments resulting in improved growth and immune performance of marron.

Temperature and hypoxia trigger developmental phenotypic plasticity of cardiorespiratory physiology and growth in the parthenogenetic marbled crayfish, Procambarus virginalis Lyko, 2017.

Attempting to differentiate phenotypic variation caused by environmentally-induced alterations in gene expression from that caused by actual allelic differences can be experimentally difficult. Environmental variables must be carefully controlled and then interindividual genetic differences ruled out as sources of phenotypic variation. We investigated phenotypic variability of cardiorespiratory physiology as well as biometric traits in the parthenogenetically-reproducing marbled crayfish Procambarus virginalis Lyko, 2017, all offspring being genetically identical clones. Populations of P. virginalis were reared from eggs tank-bred at four different temperatures (16, 19, 22 and 25 °C) or two different oxygen levels (9.5 and 20 kPa). Then, at Stage 3 and 4 juvenile stages, physiological (heart rate, oxygen consumption) and morphological (carapace length, body mass) variables were measured. Heart rate and oxygen consumption measured at 23 °C showed only small effects of rearing temperature in Stage 3 juveniles, with larger effects evident in older, Stage 4 juveniles. Additionally, coefficients of variation were calculated to compare our data to previously published data on P. virginalis as well as sexually-reproducing crayfish. Comparison revealed that carapace length, body mass and heart rate (but not oxygen consumption) indeed showed lower, yet notable coefficients of variation in clonal crayfish. Yet, despite being genetically identical, significant variation in their morphology and physiology in response to different rearing conditions nonetheless occurred in marbled crayfish. This suggests that epigenetically induced phenotypic variation might play a significant role in asexual but also sexually reproducing species.

Quantification of proteomic profile changes in the hemolymph of crayfish during in vitro coagulation.

Hemolymph is the circulatory fluid that fills the body cavity of crustaceans, analogous to blood in vertebrates. Hemolymph coagulation, similar to blood clotting in vertebrates, plays a crucial role in wound healing and innate immune responses. Despite extensive studies on the clotting process in crustaceans, no comparative quantitative analysis of the protein composition of non-clotted and clotted hemolymph in any decapod has been reported. In this study, we used label-free protein quantification with high-resolution mass spectrometry to identify the proteomic profile of hemolymph in crayfish and quantify significant changes in protein abundances between non-clotted and clotted hemolymph. Our analysis identified a total of two-hundred and nineteen proteins in both hemolymph groups. Furthermore, we discussed the potential functions of the top most high and low-abundant proteins in hemolymph proteomic profile. The quantity of most of the proteins was not significantly changed during coagulation between non-clotted and clotted hemolymph, which may indicate that clotting proteins are likely pre-synthesized, allowing for a swift coagulation response to injury. Four proteins still showed abundance differences (p < 0.05, fold change>2), including C-type lectin domain-containing proteins, Laminin A chain, Tropomyosin, and Reverse transcriptase domain-containing proteins. While the first three proteins were down-regulated, the last one was up-regulated. The down-regulation of structural and cytoskeletal proteins may affect the process of hemocyte degranulation needed for coagulation, while the up-regulation of an immune-related protein might be attributed to the phagocytosis ability of viable hemocytes during coagulation.