Swimming Crab Research Articles

Identifying sex-differential gene expression in the antennal gland of the swimming crab by transcriptomic analysis

The antennal glands (AnGs) are recognized as an important organ that functions in ion regulation and excretion in decapods. Previously, many studies had explored this organ at the biochemical, physiological, and ultrastructural levels but had few molecular resources. In this study, the transcriptomes of the male and female AnGs of Portunus trituberculatus were sequenced using RNA sequencing (RNA-Seq) technology. Genes involved in osmoregulation and organic/inorganic solute transport were identified. This suggests that AnGs might be involved in these physiological functions as versatile organs. A total of 469 differentially expressed genes (DEGs) were further identified between male and female transcriptomes and found to be male-biased. Enrichment analysis showed that females were enriched in amino acid metabolism and males were enriched in nucleic acid metabolism. These results suggested differences in possible metabolic patterns between males and females. Furthermore, two transcription factors related to reproduction, namely AF4/FMR2 family members Lilli (Lilli) and Virilizer (Vir), were identified in DEGs. Lilli was found to be specifically expressed in the male AnGs, whereas Vir showed high expression levels in the female AnGs. The expression of up-regulated metabolism and sexual development-related genes in three males and six females was verified by qRT-PCR and the pattern was found to be consistent with the transcriptome expression pattern. Our results suggest that although the AnG is a unified somatic tissue composed of individual cells, it still demonstrates distinct sex-specific expression patterns. These results provide foundational knowledge of the function and differences between male and female AnGs in P. trituberculatus.

Spawning potential ratio of comercially important spiny lobster in Donggala Waters Central Sulawesi

Currently, spiny lobster fishery in Indonesia ranks third as an export commodity from the crustacean subphylum after shrimp and blue swimming crab – mud crab. Most of the spiny lobster export needs still rely on wild population resulting in fishing pressure. To ensure the sustainability of spiny lobster stocks, information of the Spawning Potential Ratio (SPR) is needed. This study aims to analyze SPR of spiny lobsters of Panulirus femoristriga and P. versicolor species. The research was conducted in May − November 2022 in Donggala Regency waters. SPR analysis uses the Length-Based SPR method. The results showed that the stock status of P. femoristriga and P. versicolor had experienced growth overfishing and recruitment overfishing with estimated SPRs of 17 and 11%, respectively. Fishing regulations are needed to maintain a sustainable spiny lobster fishery through increased participation of stakeholders in the implementation, monitoring and evaluation of the regulations set by the government. In addition, it is necessary to reduce of efforts 27 − 33% from the current exploitation rate to E50 0.28.

Sail technology on fishing vessel for blue swimming crab catching application - A review

The increase in fuel prices will gradually have an impact on the capture fisheries sub-sector, especially the fishermen. Sail technology is an alternative that can be used to save fuel oil, although it is realized that this technology cannot completely replace the diesel motor that is commonly used in fishing operations. This study will explain the application opportunities of sail technology on fishing vessels for blue swimming crab (Portunus pelagicus) in the deep waters of the Java Sea. This fishing ground is more than 12 nautical miles from the coast. Using sail technology on fishing vessels is very dependent on the characteristics of wind speed and direction. This discussion explores the relationship between the west and east monsoons in the Java Sea with the direction of fishing trip. Technological difficulties and current challenge in sail technology on fishing vessel for blue swimming crab are identified. The possible ideas for future research in this field are also discussed.

Effects of Different Habitat Space on Growth Performance and Nutritional Composition of Swimming Crabs (Portunus trituberculatus)

Habitat space is crucial for animals. This experiment explored the effect of four different farming acreages (0.5 m2, 1 m2, 10 m2, and 100 m2) on survival rate, growth performance, and muscle nutrition composition of swimming crabs (Portunus trituberculatus) at the farming density of 2 ind/m2. The results showed that the survival rate of the crabs that live in the 10 m2 group and live in 0.5 m2 alone had the highest survival rate of 20.50% and 20%, better than the 1 m2 group and the 100 m2 group with the lowest of 12.00% and 13% ( P < 0.05 ). There was no significant difference between final body weight and final carapace width among the 4 groups ( P > 0.05 ). The crude lipid content was the highest in 1 m2, which was significantly higher than in 0.5 m2 ( P < 0.05 ). The crude protein content in the 1 m2 and 10 m2 groups was significantly higher than that in the 0.5 m2 and 100 m2 groups ( P < 0.05 ). The results of the three conventional nutrients showed that there was no positive correlation between the muscle conventional nutrients and the farming area. The polyunsaturated fatty acid part of the 100 m2 and 10 m2 group was significantly different from the 1 m2 and 0.5 m2 groups ( P < 0.05 ). The results show that farming crab alone is not better than together, and a small aquaculture acreage helps to improve the muscle nutrition composition of the swimming crabs, while a large aquaculture acreage is more conducive to balance the development of nutrition. Overall, 10 m2 of habitat space was more economically feasible in practice.

Light Intensity and Photoperiod Interaction Affects the Survival, Development, Molting and Apoptosis-Related Genes of Swimming Crab Portunus trituberculatus Larvae

A 19-day experiment was conducted to investigate the optimal light intensity and photoperiod combination for larval swimming crabs Portunus trituberculatus in terms of survival, development, and apoptosis-related gene expression. Two photoperiods, i.e., 12 and 18 h photophases, and three light intensities, i.e., 126.08, 173.17, and 191.53 μmol m−2 s−1, were used in the study. The results showed that the cumulative survival rate (CSR) of larvae decreased with the increasing light intensity, and the adverse effect of high light intensity was only observed in long photophase groups. On the contrary, a long photophase and low light intensity elevated the CSR from zoea III to juvenile crabs. A long photophase also accelerated the development of zoea III larvae and upregulated the molting-related (ecr and rxr) and apoptosis-related (jnk, p53, and bcl-2) gene expressions. Taken together, the present study suggested that the light intensity and the photoperiod had a combined effect on P. trituberculatus larvae. The optimal light intensity and photoperiod for P. trituberculatus larvae were 126.08 μmol m−2 s−1 and an 18 h photophase, respectively.

Survival, Energy Status, and Cellular Stress Responses of the Juvenile Swimming Crab Portunus trituberculatus under Acute Nitrite Stress

Nitrite is a common pollutant encountered in aquaculture systems. During intensive hatchery, accumulation of nitrite can cause massive mortality of juvenile crustaceans. However, the nitrite toxicity and cellular stress responses in juvenile crustaceans is not clearly understood. Here, we investigate the survival, energy metabolism, and cellular stress responses in juvenile P. trituberculatus, an important aquaculture species in China, under acute nitrite stress. The results revealed nitrite resulted in a significant decrease in survival rate of juvenile swimming crab. After nitrite exposure, the activity of catabolic enzymes, such as HK, PK, CS, and CPT-1, were initially enhanced, and then they showed significant decrease at the late stage of exposure, accompanied by reduction in ATP and adenylate energy charge (AEC). The impaired energy homeostasis was possibly associated with disturbed AMPK signaling and enhanced anaerobic metabolism, which was indicated by the high levels of LDH activity and HIF-1α expression. Furthermore, we found that nitrite stress can depress antioxidant systems and unfold protein responses, causing oxidative damage and endoplasmic reticulum (ER) stress, and this, in turn, can trigger autophagy and apoptosis through both caspase-dependent and caspase-independent pathways. The results of the present study improve our understanding regarding adverse effects of nitrite on P. trituberculatus and provide valuable information for hatchery management.

Modification of Eco-Friendly Collapsible Crab Pot of Blue Swimming Crab in Pangkep Regency, Indonesia

The aim of this study is to determine the effect of mesh size on the catches of small crab (Portunus sp.) both in number, carapace length (CL), and catchability between modified and control collapsible crab pot. This study used mesh size of the wrapping net (PE) from 2.5 cm (± 1 inch) to 7.0 cm (± 2.5 inches) with 20 units and 20 repetitions (trips). The results showed that different mesh size has a significant effect on the catch of the pot. However, the catch of a 2.5-inch mesh size- showed a larger carapace length = 42 individuals (85.7 %), while the escaped number was 44 individuals (63.7%) in the unfeasible category catch while the remaining 25 samples (36.2%) are eligible to catch. The Anova test on the catch of crab pot with a mesh size of 2.5 inches and 1 inch based on CL showed F-count > F_table (54.213 > 3.016) or sig. value <0.05 (0.00<0.05) which means that the size of the crab pot had a significant effect on CL. This identified that the size of the collapsible crab pot with a mesh size of 2.5 inches could pass small crabs and can only catch large crabs.

Crabs ride the tide: incoming tides promote foraging of Giant Mud Crab (Scylla serrata)

BackgroundEffective fisheries management of mobile species relies on robust knowledge of animal behaviour and habitat-use. Indices of behaviour can be useful for interpreting catch-per-unit-effort data which acts as a proxy for relative abundance. Information about habitat-use can inform stocking release strategies or the design of marine protected areas. The Giant Mud Crab (Scylla serrata; Family: Portunidae) is a swimming estuarine crab that supports significant fisheries harvest throughout the Indo-West Pacific, but little is known about the fine-scale movement and behaviour of this species.MethodsWe tagged 18 adult Giant Mud Crab with accelerometer-equipped acoustic tags to track their fine-scale movement using a hyperbolic positioning system, alongside high temporal resolution environmental data (e.g., water temperature), in a temperate south-east Australian estuary. A hidden Markov model was used to classify movement (i.e., step length, turning angle) and acceleration data into discrete behaviours, while also considering the possibility of individual variation in behavioural dynamics. We then investigated the influence of environmental covariates on these behaviours based on previously published observations.ResultsWe fitted a model with two well-distinguished behavioural states describing periods of inactivity and foraging, and found no evidence of individual variation in behavioural dynamics. Inactive periods were most common (79% of time), and foraging was most likely during low, incoming tides; while inactivity was more likely as the high tide receded. Model selection removed time (hour) of day and water temperature (°C) as covariates, suggesting that they do not influence Giant Mud Crab behavioural dynamics at the temporal scale investigated.ConclusionsOur study is the first to quantitatively link fine-scale movement and behaviour of Giant Mud Crab to environmental variation. Our results suggest Giant Mud Crab are a predominantly sessile species, and support their status as an opportunistic scavenger. We demonstrate a relationship between the tidal cycle and foraging that is likely to minimize predation risk while maximizing energetic efficiency. These results may explain why tidal covariates influence catch rates in swimming crabs, and provide a foundation for standardisation and interpretation of catch-per-unit-effort data—a commonly used metric in fisheries science.

Morphological Description of Megalopal Stages of Three Portunid Species (Decapoda, 2 Brachyura, Portunidae) from Indus Deltaic Area (northern-Arabian Sea)

The larvae of crustaceans, including those of brachyuran crabs, are a significant part of zooplanktonic communities constituting an ecologically important fraction of the pelagic communities. The present study describes taxonomic studies on three megalop stages of Portunus pelagicus (Linnaeus, 1758), Charybdis feriatus (Linnaeus, 1758) and Carcinus maenas (Linnaeus, 1758) belonging to family Portunidae collected from Indus deltaic creek system. Zooplankton samples were collected from three locations: Shahbandar 24°15’48.083’N, 67°90’15’333’E, Ketibandar 24°9’16.06’N, 67°27’7.64’E and Korangi creek 24°48’18.80’’N, 67°12’30.31’E during April to October 2018. No data available on taxonomic studies of portunid megalops upto species level from Paksitan, hence this is a first attempt to examine and to describe taxonomic features of megalops collected in the zooplankton samples. This study will contribute to the scientific knowledge on megalops taxonomy and identification as well as be useful for future research by taxonomists and biologists.

A swimming crab portunus trituberculatus re-identification method based on RNN encoding of striped key regions

A swimming crab portunus trituberculatus re-identification method based on RNN encoding of striped key regions

The effectiveness of weather index insurance in managing mariculture production risk

AbstractMariculture is a high‐risk industry that is susceptible to weather disasters. However, due to moral hazard, adverse selection and high transaction costs, traditional indemnity insurance policies are not available. An emerging alternative is the development of weather index mariculture insurance. This research assesses the effectiveness of weather index mariculture insurance by using the swimming crab precipitation index insurance as an example. The theoretical and empirical results suggest that weather index mariculture insurance is not always effective. It cannot be guaranteed to promote the welfare of mariculturists and reduce the tail risk of income, especially in the case of gross rates. However, in the case of low basis risk, it could be a viable option for the government because of the low subsidy cost required.

Acute metabolic responses of two marine brachyuran crabs to dilute seawater: The aerobic cost of hyper regulation.

Hepatuspudibundus ("flecked box crab") is a stenohaline osmoconfomer, and restricted to marine habitats. Callinectes danae ("swimming crab Dana") lives in coastal/estuarine waters and is a weak hyper regulator. There is no consensus on which strategy is more expensive metabolically face salinity challenges: conformation with higher dependence on cell volume regulation, or hyper regulation, alleviating the need for intense cell volume regulation. Crabs were probed for their acute response to dilute seawater through exposures to salinities 35‰, 30‰, 25‰, and 20‰for 2, 4, and 6 h. Hemolymph osmolality, lactate, and ions (chloride, sodium, magnesium, potassium) were assayed, as well as muscle water content. Water dissolved oxygen, ammonia, and pH levels were also measured. H. pudibundus conformed for osmolality and displayed increase in muscle hydration along the decrease in salinity down to 25‰, while C. danae efficiently maintained hemolymph osmo ionic stability, consumed more oxygen, acidified more the water, and released more ammonia. In 25‰,both species spent energy: H. pudibundus putatively controlling cell volume, and C. danae regulating hemolymph concentrations. In 20‰, H. pudibundus closed itself, avoiding the contact of the interface epithelia with the external environment and producing much lactate, whereas C. danae spent more energy (aerobic) in extracellular osmo ionic stability. Under these conditions, anisosmotic extracellular regulation (together with additional cell volume regulation) is more oxygen consuming than osmoconformation with a putatively more intense challenge to cell volume. The exposure to hyposalinity limits the occupation of estuarine environments by H. pudibundus in short and middle term.

Molecular identification of an insulin-like peptide from the swimming crab Portunus trituberculatus and evidence for its glucoregulation function

Insulin-like peptides (ILPs) are essential to the animal kingdom for regulating growth and development, reproduction, behavior, metabolism, and lifespan. In crustaceans, the most well-known ILP is insulin-like androgenic gland hormone, a key hormone in regulating sex differentiation and reproduction. Identification of other ILPs and their functions are still limited. In this study, an insulin-like peptide gene of the swimming crab Portunus trituberculatus was cloned and characterized. Its transcripts were mainly found in nerve tissues and expression could be induced by glucose, implying a putative role in glucoregulation. After depletion of endogenous ILP, injection of ILP dsRNA (dsILP) significantly elevated blood glucose levels and recombinant ILP (rILP) decreased hemolymph glucose levels, further clarifying the involvement of acquired ILP in hemolymph glucose regulation. Injection of dsILP decreased PtAkt, PtGS, PtPFK and increased PtGSK and PtPEPCK gene expression. The opposite profile was observed after glucose and rILP injection, indicating that PtILP might negatively regulate hemolymph glucose levels via the IIS (insulin/IGF-1 signaling) pathway by inhibiting gluconeogenesis and promoting glycogen synthesis and glycolysis. This study has refined the mechanism of glucose regulation in crustaceans and laid the foundation for further studies on ILP function.

Ammonia Stress Disturbs Moult Signaling in Juvenile Swimming Crab Portunus trituberculatus

Ammonia is a significant concern during hatchery culture in brachyuran species, and its accumulation may lead to abortive moulting and large-scale deaths of the early juveniles. To date, the underlying mechanism for ammonia-induced alteration of the moulting process is still unknown. In this study, we aimed to investigate the effects of ammonia on the moulting as well as the potential mechanisms in early juveniles of the swimming crab Portunus trituberculatus, an important aquaculture species in China. We evaluated the survival rate and moulting rate of the juvenile crabs (C2) and analyzed the expression pattern of the genes in key components of molt signaling during a complete moulting cycle under different concentrations of ammonia nitrogen (the control group: <0.1 mg/L; the LA group: 5 mg/L; and the HA group: 20 mg/L). The results showed that: (1) the survival rate in the LA and HA groups was lower than that in the control group at the end of the experiment, and moulting death syndrome (MDS) was only observed in the HA group; (2) the moulting rate was higher in the LA group and lower in the HA group compared to the control group; (3) consistent with the results of the moulting experiment, MIH showed decreased expression, and genes related to ecdysteroid synthesis, ecdysteroid receptors, and responsive effectors exhibited increased expression in the LA group compared to the control group; and (4) although MIH expression was upregulated, increased expression of the genes associated with ecdysteroid synthesis, ecdysteroid receptors and downstream effectors still observed in the HA group. Our results indicated that low levels of ammonia can promote moulting in juvenile swimming crabs by inhibiting the expression of MIH and activating moult signaling, whereas high levels of ammonia inhibit moulting and lead to MDS through impairing moult signaling.

A quantitative analysis of greenhouse gases emissions from catching swimming crab and snow crab through cross-analysis of multiple fisheries

A quantitative analysis of greenhouse gases emissions from catching swimming crab and snow crab through cross-analysis of multiple fisheries

Reveal The Growth Pattern and Condition Factors of Blue Swimming Crabs (Portunus pelagicus) in Estuary Ecosystem of Berombang, Labuhanbatu Regency, North Sumatera

The Blue swimming crab Portunus pelagicus which comes from subphylum Crustacea, specifically the Portunidae family, is one of the potential crabs that have high economic value in Labuhanbatu regency. This study aimed to reveal information on condition factors and the population growth pattern of P. pelagicus in the ecosystem of the Berombang river estuary. This study was conducted from November 2021 to January 2022, using the purposive random sample method in determining the sampling points. In collecting the samples of P. pelagicus, the researchers used fish traps called bubu with fresh fish as bait. Results showed that the growth pattern of P. pelagicus was negatively allometric, in which values ​​for males and females were 1.1552 and 2.2727, respectively. Furthermore, the results of the correlation analysis between the physical-chemical of waters to abundance of P. pelagicus indicated that positive correlation for water temperature (0.835), dissolved oxygen (DO) (0.778), and salinity (0.726) had an effect on the presence of P. pelagicus.

Population Genetic Structure of the Blue Swimming Crab (Portunus pelagicus) Along the Andaman Sea Coast of Thailand

The blue swimming crab (Portunus pelagicus) is a valuable commercial species. In Thailand, the consumption of the blue swimming crab is increasing. To construct an effective sustainable management plan, genetic information is required. Knowledge of natural stock genetic information can help policymakers design fishing and conservation management policies to maintain genetic diversity. In our study, we examined the genetic structure of the blue swimming crab population on the Andaman Sea coast of Thailand. Partial sequences of the mitochondrial DNA control region (mtDNA CR) with a size of 369-371 base pairs were studied in 150 individuals collected from five sampling sites along Thailand's Andaman Sea coast. Seventy-one haplotypes were characterized by 127 polymorphic sites, indicating high haplotype diversity but low nucleotide diversity across five localities. The multiple tests of population genetic analysis showed a lack of genetic structure. The absence of genetic structure was possibly caused by a high level of gene flow due to the larval blue swimming crab's high dispersal ability. Demographic history findings indicate that the blue swimming crab population has expanded. The findings of our study can be used to guide the management of the blue swimming crab in this region of the Andaman Sea to conserve genetic diversity.

The first description of the blue swimming crab (Portunus pelagicus) transcriptome and immunological defense mechanism in response to white spot syndrome virus (WSSV)

In the global shellfish farming industry, white spot syndrome virus (WSSV) is a major cause of mortality and a significant factor in economic losses. However, information on molecular immune responses to WSSV in blue swimming crabs (Portunus pelagicus) has never been reported. First, viral loads were measured in the gills, hepatopancreas, intestines, subcuticular epithelium and hemocytes of blue swimming crabs (50 ± 10 g) (n = 4) after WSSV induction at 0, 24, 48 and 96 h post injection (hpi). A significant increase in WSSV particles was observed in gills at 48 and 96 hpi, as supported by histopathology. To further investigate the acute immune response to WSSV, total RNA from the same gill tissues at 0, 24, and 96 hpi was used to construct 16 high-quality RNA-seq cDNA libraries. In summary, 162,740 unigenes were discovered in these transcriptomic libraries analyzed with the GO, KO, KOG, NR, NT, PFAM and SwissProt databases. Intensive sequence analysis against control crabs using three major categories of gene oncology (GO) of DEGs, biological processes (BPs), molecular functions (MFs), and cellular components (CCs), indicated that induction of WSSV in blue swimming crabs strongly affected the immune responses of the target animals significantly during the early stages of infection from 24 to 96 hpi. Furthermore, KEGG identified approximately twenty biological pathways of gene expression that were both downregulated and upregulated. Interestingly, at 24 and 96 hpi, several immune-related genes involved in virus defense in the blue swimming crab, particularly crustin 2, chitinase, anti-lipopolysaccharide, proteinase inhibitor, and lysozyme, were highly expressed during the WSSV early infection stages. At the same time, viral mRNA transcripts, including WSV289, WSV343, WSV306, deoxyuridine 5’ triphosphate nucleohydrolase, RING finger containing E3 ubiquitin-protein ligase WSV403 and WSV404, were recorded in the top twenty upregulated genes. Moreover, some immune-responsive genes related to growth development, such as chitinase, tubulin alpha and beta chains, trypsin, and the cathepsin family, were also differentially expressed during these periods. Expression validation of 20 upregulated and 11 downregulated immune-related genes using qRT‒PCR showed similar patterns with transcriptome information. Overall, the data showed that during WSSV infection, a number of immune-, metabolism-, and growth-related pathways were activated, and several of the pathways involved differed depending on the stage of virus invasion. These findings could effectively help us better understand the impact of WSSV on the physiology of blue swimming crabs and serve as a valuable reference for future research on the immune system and disease control in this target species.

Adaptive changes of swimming crab (Portunus trituberculatus) associated bacteria helping host against dibutyl phthalate toxification

The pollution of dibutyl phthalate (DBP) in aquatic environments is becoming an extensive environmental problem and detrimental to aquatic animals. Here, we quantified the response pattern of the bacterial community and metabolites of swimming crab (Portunus trituberculatus) juveniles exposed to 0.2, 2, and 10 mg/L DBP using 16 S rRNA gene amplicon sequencing coupled with metabolomic technique. The results showed that DBP changed the bacterial community compositions in a concentration-dependent pattern and decreased the Shannon index at the second developmental stage of the swimming crabs. The Rhodobacteraceae taxa were specifically enriched by crabs when challenged by 2 and 10 mg/L DBP, with an increased in Shannon index and enhanced drift in its assembly. Moreover, DBP changed the metabolic profiling of the swimming crab, highlighted by increased levels of lactate, valine, methionine, lysine, and phenylalanine in the 10 mg/L DBP-exposed crabs. Rhodobacteraceae presented the most considerable contribution to the metabolic potentials in phthalate and benzoate degradation, lactate production, and amino acid biosynthesis. Overall, our results indicated an adaptive change of crab-associated bacteria helped the host resist DBP stress. The findings extend our insights into the relationship between the microbiota and its host metabolism under DBP stress and reveal the potential microbiota modalities for DBP detoxification.

Diets of Portunus segnis (Forskål, 1775) (Decapoda, Portunidae) from the Persian Gulf, Iran

Abstract The food habits of the blue swimming crab, Portunus segnis (Forskål, 1775) were investigated using specimens collected from trawl catches in the north-east of the Persian Gulf, from June 2018 to May 2019. Feeding habits of 304 adult female crabs, ranging from 2.6 to 8.7 cm in carapace length, were analysed. The stomach content of examined crabs showed to consist of crustaceans, fish, molluscs, unidentifiable material, sea grass and foraminiferans. We realized that the vacuity index did not show significant differences between ovigerous and non-ovigerous females (). Nevertheless, there was a significant difference in the vacuity index between barnacle-carrying crabs — Chelonibia testudinaria — and crabs without barnacles (). There was no significant difference observed in the quantity of the eaten foods between large and medium-sized groups of crabs. But a significant difference was observed between large- and small-sized crabs, and small- and medium-sized crabs. Moreover, significant differences were observed in food items between barnacle-carrying crabs and crabs without barnacles. Also, the percentage of empty stomachs was higher in ovigerous females than in non-ovigerous females.