Red Swamp Crayfish Procambarus Clarkii Research Articles

Can fish lifts aid upstream dispersal of the invasive red swamp crayfish (Procambarus clarkii) past high‐head hydropower plants?

AbstractMany types of fish passage facilities have been built worldwide to mitigate river fragmentation by instream barriers and partially restore upstream movements of fish. Among these, fish lifts are a design that enables fish to pass through high‐head obstacles (>15 m height) and can be considered the most cost‐effective fishway. However, fishways may also be used by non‐native invasive species to disperse and impact new areas and organisms upstream. As far as the authors are aware, this short communication is the first record of the red swamp crayfish (Procambarus clarkii) passing through a fish lift. The lift, built at the Touvedo hydropower plant on the Lima River (northwestern Portugal), was mainly designed for the upstream passage of diadromous fish. Fish‐lift use and upstream passage of two crayfish occurred over 3 years (November 2017–October 2020) during periods of turbine shutdown and high water temperatures (18°C). In the present case, the crayfish passage should not pose a serious threat due to the limiting characteristics of the upstream lotic environment. Nevertheless, despite the small sample size, this study shows the importance of considering the passage of invasive crayfish species while planning future fishways and the need to continuously monitor such facilities to detect the passage of this and other non‐native invasive species.

Melanized Lesions in Red Swamp Crayfish (Procambarus clarkii) Reared in the Laboratory Conditions

Melanized Lesions in Red Swamp Crayfish (Procambarus clarkii) Reared in the Laboratory Conditions

Influence of Dietary Replacement of Fish Meal with Crayfish Shell Meal on the Skin Coloration, Muscle Texture, and Amino Acid Composition of Oujiang Color Common Carp Cyprinus carpio var. color

AbstractAn 8‐week feeding trial was conducted to investigate the influence of dietary replacement of fish meal with crayfish shell meal (red swamp crayfish Procambarus clarkii) on the skin coloration, muscle texture, and amino acid composition of Oujiang color common carp Cyprinus carpio var. color. One‐hundred‐eighty fish with average initial weight of 3.0 ± 0.5 g were fed with two isonitrogenous and isolipidic diets (a control diet and a crayfish shell meal diet with 25% substitution of fish meal protein [CSM25]). At the termination of the feeding trial, there were no significant differences between the two groups in terms of lightness (L*), redness (a*), and yellowness (b*) values. Interestingly, one unexpected finding was the extent to which the highest value for total color difference (ΔE) was observed in caudal skin. The springiness, adhesiveness, cohesiveness, gumminess, and chewiness of the muscle were not affected by the CSM25 diet in this study. Muscle hardness was decreased by dietary supplementation with crayfish shell meal, although this decrease was not significant. Notably, there were significant increases in the levels of threonine, leucine, and lysine in the CSM25 group. The current results indicate that crayfish shell meal can alter some essential amino acid levels in muscle. These findings might help others to better understand the influence of dietary replacement of fish meal with crayfish shell meal on skin coloration, muscle texture, and amino acid composition.

Health risk assessment and bioaccumulation of heavy metals in Procambarus clarkii from six provinces of China.

Contamination with heavy metals in wild red swamp crayfish (Procambarus clarkii) from 7 different geographical areas in six provinces of China (Hubei, Hunan, Jiangxi, Anhui, Jiangsu, and Shandong) was evaluated. Concentrations of chromium (Cr), arsenic (As), lead (Pb), cadmium (Cd), and mercury (Hg) in the abdominal muscle, gonad, and hepatopancreas were determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic fluorescence spectrometer (AFS). Except for the Cd content in the hepatopancreas, the contents of selected heavy metals in three different tissues were significantly lower than the proposed limits provided by United States Environmental Protection Agency (USEPA). The maximum accumulations of Cd and Pb were in the hepatopancreas, while the maximum accumulation of As was in the gonad, and the maximum accumulations of Hg and Cr were in the abdominal muscle. The highest contents of Cr, Hg, and Pb were all detected in Dongting Lake, Hunan, which was consistent with the trend of the metal pollution index (MPI). Risk value of the target hazard quotient (THQ) was below 1.0, suggesting that the intake of selected heavy metals through crayfish consumption would not pose a significant health risk to consumers.

Detection of Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV, Decapod Penstylhamaparvovirus 1) in Commodity Red Claw Crayfish (Cherax quadricarinatus) Imported into South Korea

Freshwater crayfish, which are cultivated in aquaculture, are economically important for food and ornamental purposes. However, relatively few studies have focused on potentially pathogenic viruses in crayfish compared to in penaeid shrimp. Commodity red claw crayfish (Cherax quadricarinatus; 400 crayfish in 10 batches) and red swamp crayfish (Procambarus clarkii; 40 crayfish in 2 batches) imported into South Korea from Indonesia and China were screened by PCR to detect infectious hypodermal and hematopoietic necrosis virus (IHHNV or Decapod penstylhamaparvovirus 1). IHHNV was detected in tissue samples pooled from nine out of ten batches of red claw crayfish imported from Indonesia. Phylogenetic analysis of PCR amplicons from representative pools clustered the IHHNV strain with infectious-type II sequences commonly detected in Southeast Asian countries rather than with type III strains detected previously in whiteleg shrimp (Penaeus vannamei) cultured in South Korea. IHHNV DNA was detected most frequently in the muscle (eight batches, 66.7% samples), followed by in the hepatopancreas (five batches, 41.7% samples) and gills tissue (three batches, 25.0% samples). These data suggest that red claw crayfish could be a potential carrier of the virus and that quarantine procedures must be strengthened in South Korea to avoid importing infectious types of IHHNV in commodity crustaceans such as red claw crayfish.

A chromosome-level reference genome of red swamp crayfish Procambarus clarkii provides insights into the gene families regarding growth or development in crustaceans

Red swamp crayfish Procambarus clarkii is an ecologically and economically important crustacean species. Here, based on a de novo assembly strategy combining PacBio with Hi-C sequencing, we presented a high quality chromosome-level P. clarkii genome. The assembled genome is 2.75 Gb in size with a contig N50 of 216.75 kb. Transposable elements (TEs) make up the largest fraction of the genome (~79.61%), and LINEs comprise the majority of the TEs. Frequent molting and rapid growth of the red swamp crayfish may be explained by the expansion of multiple gene families regarding growth or development. Phylogenetic analysis revealed that P. clarkii diverged from Portunus trituberculatus at 278–407 million years ago (Mya). PSMC analysis identified multiple bottleneck events of the P. clarkii population between 2 kaBP to 14 kaBP. The obtained P. clarkii genome should not only facilitate us understanding the development and evolution of the crayfish species, but also contribute to the genetic improvement in future breeding selections.

State of the ART: Using artificial refuge traps to control invasive crayfish in southern California streams.

Invasive species are a widespread threat to stream ecosystems across the planet. In Southern California, USA, the invasive red swamp crayfish Procambarus clarkii (Girard, 1852) poses a significant threat to native aquatic fauna. Studies have suggested that artificial refuge traps (ARTs) resembling crayfish burrows can be used to remove invasive crayfish, but, to date, no studies have focused on optimizing ART design and deployment to maximize crayfish catch. This month-long study tested the effect of modifications on ART diameter, color, and soak time on P. clarkii catch effectiveness across 160 traps. We evaluated catch data by creating multiple candidate generalized linear mixed models predicting P. clarkii catches with different modeling parameterizations and a priori hypothesized predictor variables. During the study period, ARTs removed a total of 240 red swamp crayfish with no incidental bycatch. Larger P. clarkii (2-6-cm carapace length) were found more frequently in 5.1-cm-diameter traps, and smaller P. clarkii (1-4 cm) were found more frequently in 2.5-cm-diameter traps. Catch numbers varied between trap types, with black-colored 5.1-cm-diameter traps removing the greatest amount of the total P. clarkii caught in the study (mean = 0.27, SD = 0.29; 35% of the total caught) and black-colored 2.5-cm-diameter traps removing the least amount (mean = 0.09, SD = 0.55; 12% of the total). Further, ART deployment duration was an important predictor variable for candidate models, where ARTs with 4-d and 7-d deployment durations had lower catch/unit effort than traps with 1-d and 2-d deployments. This factorial experiment is the 1st study to suggest specific design modifications to ARTs that optimize invasive red swamp crayfish removal without incurring non-target incidental bycatch. This study demonstrates that ARTs can be a valuable tool for conservation managers interested in restoring streams through invasive crayfish removal, especially where there are sensitive biological resources.

Patterns and determinants of phenotypic variability within two invasive crayfish species

Abstract Knowledge on the ecological determinants and evolutionary processes shaping intraspecific variability in the wild remains scarce. It is particularly needed in the context of biological invasions to fully understand the consequences of invasive species on the functioning of recipient ecosystems. Using geometric morphometrics, stable isotopes, and elemental composition analyses, we quantified phenotypic variability (morphological, trophic, and stoichiometric traits) within and among invasive populations of two crayfish species with distinct invasion histories over 23 gravel pit lakes in southwest France. We sampled 12 populations of the red swamp crayfish (Procambarus clarkii Girard, 1852) and 11 populations of the spiny‐cheek crayfish (Faxonius limosus Rafinesque, 1817). We aimed at unravelling the ecological determinants and the mechanisms (neutral or adaptive) underlying the phenotypic variability among invasive populations. We demonstrate that, for each group of traits, P. clarkii and F. limosus display contrasting patterns of variance distribution across three ecological scales (population, sex, individual). Then, we demonstrate that P. clarkii trait variation in body morphology and stoichiometry is associated with both ecological and historical determinants (i.e. predation pressure, intraspecific invasion, and invasion age), and morphological traits in F. limosus vary with ecological factors only (i.e. predation pressure and abundance of P. clarkii). Finally, we highlight that different combinations of neutral and adaptive processes shaped the phenotypic variability in the two species, with a higher contribution of adaptive processes in F. limosus. Overall, these results indicate that F. limosus has already gone through local adaptation in the meta‐population while this has not yet occurred for P. clarkii, which was introduced later. This highlights that these two invasive species might have contrasting effects across ecological scales. Our study emphasises that studying invasive species can provide great knowledge on intraspecific variability and its ecological determinants and evolutionary processes in the wild. Our results also stress the need to focus on intraspecific variability in the context of biological invasions as it can be substantial across wide geographic areas.

Habitat alteration facilitates the dominance of invasive species through disrupting niche partitioning in floodplain wetlands

AbstractAimExotic species invasion often leads to declines in local and regional biodiversity, particularly in freshwater ecosystems. This biodiversity loss is generally facilitated by human activities such as land cover change and hydrological alternation. Recent advances in stable isotope analysis (SIA) have been highlighted in many studies addressing fundamental issues in invasion ecology, especially in quantifying competition for resources between native and exotic species. However, how anthropogenic disturbance influences trophic relationships among invasive and native species remains poorly understood.LocationMiddle‐lower Yangtze River Region, China.MethodsTo investigate the effects of human disturbance on interspecific trophic interactions, this study compared isotopic niche space and overlap of the introduced red swamp crayfish (Procambarus clarkii) and the native oriental river shrimp (Macrobrachium nipponense) and freshwater snail (Bellamya aeruginosa) in natural and modified wetlands.ResultsBased on carbon and nitrogen SIA, we found ubiquitous niche shifts in macroinvertebrates with increased competition, which might lead to significant niche contraction in modified habitats at both community and population scales. Moreover, the isotopic niche width of the exotic crayfish was twice as larger as that of natives at both habitats, suggesting that the exotic P. clarkii had great competitive superiority over the native species. However, the effects of habitat modification on niche overlap were inconsistent. While the niche overlap between crayfish and shrimp was significantly higher in modified habitats than in natural open waters, niche overlap between crayfish and the snail was significantly reduced.Main conclusionsCollectively, our findings highlight that the competitive outcomes of interspecific trophic interactions can be dependent on the prey availability and diversity, which embraces both the classic optimal foraging theory and competition theory to understand how environmental change, such as habitat alternation, affects the biological invasion processes.

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

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

Intra-and inter-specific competition effects on survival and growth of juvenile Procambarus acutus acutus and Procambarus clarkii

Four similar sizes eastern white river crayfish (Procambarus acutus acutus) and red swamp crayfish (Procambarus clarkii) were stocked separately to determine intra and inter-specific-competition. Three treatment levels were used three treatment levels, with six replicates tanks each with stand green rice (representing a stocking density of approximately 21 individuals per m2). This study was carried out during 90 days to determine growth and survival rate. Results showed that the growth of P. acutus acutus in the interspecific treatment tank was found higher than those grown in the intraspecific-treatment tanks. For P. clarkii, no significant differences in growth (estimated from the mean Total length, TL) were detected between treatments. The survival of the two species was the same up to the first 60 days of the experiment, while the difference in survival was only noticeable at 90 days. The survival rate of P. clarkii in the intraspecific-treatment tanks (55.0%) was higher than in the interspecific tanks (26.7%) treatment, while the survival of P. acutus acutus was found similar in two treatments. It was achieved higher survival, faster growth and larger size in P. a. acutus than P. clarkii when grown in the tank study. Size of body was important in determining competitive interactions between the two species.

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

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

Intervention of re-feeding on growth performance, fatty acid composition and oxidative stress in the muscle of red swamp crayfish (Procambarus clarkii) subjected to short-term starvation

The red swamp crayfish (Procambarus clarkii) is widely cultivated and consumed for its tender meat. The quality of P. clarkii is increasingly deteriorating due to a possible shortage of feed nutrition, posing a significant threat to its sustainability. To avoid the phenomenon mentioned above and enrich the culture technology of P. clarkii, the aim of this study was to assess the effect of re-feeding on alleviating oxidative damage caused by short-term starvation, as well as to investigate the relationship between oxidative stress and meat quality and its molecular regulation mechanism. A total of 600 crayfish weighing about 20.11 g were randomly divided into 4 groups: S0F0 (the control group), S0F3 (0 days of starvation and 3 days of re-feeding), S3F0 (3 days of starvation and 0 days of re-feeding) and S3F3 (3 days of starvation and 3 days of re-feeding). The results showed that starvation slowed down the growth of P. clarkii and significantly decreased the saturated fatty acids (SFA) contents in the muscle (P < 0.05). Meanwhile, starvation-induced production of large amounts of reactive oxygen species (ROS) in muscle, disrupted the structure of biomolecules in muscle, allowing myofiber to be destroyed, the structural basis of muscle and indirectly leading to muscle damage of P. clarkii. After three-day re-feeding, the growth performance of crayfish resumed. Besides, re-feeding induced the Nrf2/Keap1 pathway in the muscle and increased the expression level of downstream antioxidant enzyme genes, improving the ability of scavenging oxidative free radicals. The supply of feed also up-regulated the expression of MEF2a and MEF2b with the expression of MSTN being down-regulated, accompanied by a recovery of the textural properties and myofiber characteristics. Furthermore, the fatty acid composition was optimized where n3PUFA and n6PUFA mainly were changed. In summary, the growth of crayfish could be improved by re-feeding after three-day starvation and the negative impacts of starvation on muscle quality could be reversed by three-day refeeding.

First Detection of the Crayfish Plague Pathogen Aphanomyces astaci in Costa Rica: European Mistakes Should Not Be Repeated

The crayfish plague pathogenAphanomyces astaciis one of the main factors responsible for the decline in European and Asian native crayfish species. This pathogen was transported to these regions through its natural carriers, North American crayfish species, which were introduced during the last century. Since then, the carrier species and the pathogen have spread worldwide due to globalization and the highly invasive nature of these species. In Europe, five carrier species have been categorized as high-risk as they are responsible for the loss of provisioning services, which endangers freshwater ecosystems. The red swamp crayfishProcambarus clarkii, in particular, is currently one of the most concerning species as its spread threatens crayfish biodiversity and freshwater ecosystems worldwide. In this study, we describe the first detection ofA. astaciin an introduced population ofP. clarkiiin Central America, specifically in Costa Rica. Using molecular approaches, we analyzed 48 crayfish samples collected from Reservoir Cachí and detected the presence ofA. astaciin four of these samples. The introduction ofP. clarkiiand the incorrect management of the species (related to its fishery and the commercialization of live specimens) over the past decades in Europe are mistakes that should not be repeated elsewhere. The detection of the pathogen is a warning sign about the dangerous impact that the introduction of this invasive crayfish may have, not only as a carrier of an emerging disease but also as a direct risk to the invaded ecosystems. Our results may serve to (1) assess current and future consequences, and (2) direct future research activities, such as determining the potential impacts ofA. astacion native decapod species, or on other introduced crayfish species that are used for aquaculture purposes, such asCherax quadricarinatus.

Herbicide atrazine exposure induce oxidative stress, immune dysfunction and WSSV proliferation in red swamp crayfish Procambarus clarkii

Atrazine is considered as a potential environmental endocrine disruptors and exhibits various toxic effects on animals. It has a great impact in the aquatic ecosystems, but there are few studies on its immunotoxicity in crustaceans. In the present study, the Procambarus clarkii were utilized to assess the immune toxicity after 0.5 mg/L and 5 mg/L atrazine exposure. A significant decrease in total hemocytes count (THC) was observed at 5 mg/L atrazine exposure throughout the experiment. The activities of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were significantly inhibited, but the content of reactive oxygen species (ROS) and malondialdehyde (MDA) were up-regulated, indicating the potential oxidative stress. The analysis of the integrated biomarker response (IBR) showed the induction of oxidative stress biomarkers and the inhibition of antioxidants. After 5 mg/L atrazine exposure for 144 h, the integrity of crayfish hepatopancreas was destroyed with disappeared connections between tubules and increased liver tubules vacuoles. The relative expression levels of different immune genes in hepatopancreas after atrazine exposure were measured. Most of these genes were suppressed and exhibited a certain dose-dependent effect. The results of crayfish white spot syndrome virus (WSSV) replication shown the amount of virus in muscle was significantly higher and exhibited a higher mortality rate at 5 mg/L group than other groups. The present study determined the impact of atrazine exposure on WSSV outbreaks, and also provide an important basis for further assessing the occurrence of pesticides on diseases of P. clarkii.

Environment and host-related factors modulate gut and carapace bacterial diversity of the invasive red swamp crayfish (Procambarus clarkii)

The invasive red swamp crayfish Procambarus clarkii is present in most of the Portuguese rivers with well-known economic and environmental impacts, being also an important reservoir for many fungal and bacterial pathogens that can affect native aquatic fauna. Here the bacterial microbiota of the gut and carapace of the red swamp crayfish from three distinct localities in Portugal was characterized, using a metataxonomic approach. We tested whether biological measurements (sex, cephalotorax lenght, body condition and stress through glucose measurements) and sampling locality can be used as predictors of alpha and beta bacterial diversity. Results showed that the carapace microbiota are more responsive to differing environmental conditions than the gut microbiota, which are likely more affected by host factors, such as sex. Additionally, we have also found several potential pathogens in the microbiota of the analyzed crayfish. Our data provide a relevant baseline of the red swamp crayfish microbiota but highlight the need for further research, namely to fully characterize its role as a vector for bacterial diseases in freshwater ecosystems.

Effects ofPortulaca oleraceawhole diet on pigments and fatty acids profiles of juvenile red swamp crayfish (Procambarus clarkiiGirard, 1852) under laboratory conditions

A 10-week feeding trial was carried out to emphasize the effects of purslane weed (Portulaca oleracea) whole diet on pigmentation and fatty acids profile of juvenile freshwater red swamp crayfish Procambarus clarkii. Purslane weed is an annual succulent herb easily found in tropical and temperate regions showing a high-quality PUFA profile and carotenoid content. Crayfish fed with P. oleracea were compared with two groups fed with aquatic macrophytes control diets. At the end of the experiment, each group showed a distinct fatty acid composition, with crayfish feeding P. oleracea that exhibited significantly higher n-3 PUFA content (1.01 mg × 100 g−1) and total carotenoids (mainly astaxanthin) concentration (72.2 mg × kg−1). In natural conditions, plants are not used as primary foodstuff by crayfish, but in extensive and semi-intensive aquaculture, they could bring supplementary nutrition benefits to crayfish without affecting growth performance. P. oleracea could represent a promising ingredient in crayfish diets, or in new artificial feeds, given its added values in terms of carotenoids and polyunsaturated fatty acids. The results of this study might encourage further research aimed at defining the optimal percentages of P. oleracea inclusion in sustainable crayfish diets.

Hepatopancreas-Specific Lectin Participates in the Antibacterial Immune Response by Regulating the Expression of Antibacterial Proteins.

The hepatopancreas is an important digestive and immune organ in crustacean. There were low but stable numbers of microbes living in the hemolymph of crustacean, whereas the organs (including hepatopancreas) of crustacean were immersed in the hemolymph. It is very important to study the immune mechanism of the hepatopancreas against bacteria. In this study, a novel CTL (HepCL) with two CRDs, which was mainly expressed in the hepatopancreas, was identified in red swamp crayfish (Procambarus clarkii). HepCL binds to bacteria in vitro and could enhance bacterial clearance in vivo. Compared with the C-terminal CRD of HepCL (HepCL-C), the N-terminal CRD (HepCL-N) showed weaker bacterial binding ability in vitro and stronger bacterial clearance activity in vivo. The expression of some antimicrobial proteins, such as FLP, ALF1 and ALF5, was downregulated under knockdown of HepCL or blocked with Anti-HepCL after challenge with Vibrio in crayfish. These results demonstrated that HepCL might be involved in the antibacterial immune response by regulating the expression of antimicrobial proteins.

Effects of Two Different Macroalgae (Ulva lactuca and Jania rubens) Species on Growth and Survival of Red Swamp Crayfish (Procambarus clarkii) as Feed Additive

The effects of dietary supplementation of two different macroalgae Ulva lactuca and Jania rubens on the growth performance, survival and feed conversion ratio of juvenile red swamp crayfish juvenile (Procambarus clarkii) were investigated. Red swamp crayfish with an average total length of 56.2±6.67 mm and an average weight of 3.77±0.2 g were placed at tanks (10 crayfish at each tank) and offered diets 8 weeks. Different levels of macroalgae were added to commercial sea bass feed, and no seaweed was used as a control group. It was observed that crayfish fed with 10% feed had higher growth performance (in terms of length and weight) than those fed with 15% diet and control group (P&amp;lt;0.05). The lowest feed conversion rate was observed in juvenile crayfish fed with 15% feed (P&amp;lt;0.05). The highest survival rate was 50.0% at group fed with 15% feed, followed by 46.66% (control group) and 43.33% (10% diet groups), respectively. This study showed that there was no statistical difference in survival rate among treatment groups (P&amp;gt;0.05). However, the frequency of molting was mostly observed in the group fed with 10% diet. Therefore, the results showed that seaweed (Ulva lactuca and Jania rubens) could be used as a supplement for red swamp crayfish diet (Procambarus clarkii) at 10% to improve growth performance with no adverse effects on feed efficiency or survival rate.

G protein-coupled receptors as candidates for modulation and activation of the chemical senses in decapod crustaceans.

Many studies have characterized class A GPCRs in crustaceans; however, their expression in crustacean chemosensory organs has yet to be detailed. Class A GPCRs comprise several subclasses mediating diverse functions. In this study, using sequence homology, we classified all putative class A GPCRs in two chemosensory organs (antennular lateral flagellum [LF] and walking leg dactyls) and brain of four species of decapod crustaceans (Caribbean spiny lobster Panulirus argus, American lobster Homarus americanus, red-swamp crayfish Procambarus clarkii, and blue crab Callinectes sapidus). We identified 333 putative class A GPCRs– 83 from P. argus, 81 from H. americanus, 102 from P. clarkii, and 67 from C. sapidus–which belong to five distinct subclasses. The numbers of sequences for each subclass in the four decapod species are (in parentheses): opsins (19), small-molecule receptors including biogenic amine receptors (83), neuropeptide receptors (90), leucine-rich repeat-containing GPCRs (LGRs) (24), orphan receptors (117). Most class A GPCRs are predominately expressed in the brain; however, we identified multiple transcripts enriched in the LF and several in the dactyl. In total, we found 55 sequences with higher expression in the chemosensory organs relative to the brain across three decapod species. We also identified novel transcripts enriched in the LF including a metabotropic histamine receptor and numerous orphan receptors. Our work establishes expression patterns for class A GPCRs in the chemosensory organs of crustaceans, providing insight into molecular mechanisms mediating neurotransmission, neuromodulation, and possibly chemoreception.