Swimming Crab Research Articles

Assessing nine devices to reduce bycatch in the pink shrimp Penaeus paulensis fisheries: Lessons from field experiments with fyke nets

The adoption of bycatch reduction devices (BRD) has been widely used to reduce bycatch in several fisheries worldwide, especially in trawl nets targeting shrimps. However, the efficiency of these devices has rarely been assessed in passive nets, such as fyke nets using light attraction. This study tested the efficiency of nine BRDs in a passive fyke net fishery performed in southern Brazil, targeting the pink shrimp Penaeus paulensis. The abundance of fishes, swimming crabs and shrimp was compared using the National Oceanic and Atmospheric Administration (NOAA) testing protocol across 1) three different light attraction colours; 2) two fisheye models; 3) two square-mesh models, and; 4) two grid models. A significant reduction in bycatch was recorded when using fisheye and square mesh, however it was also noticed an important reduction in target species. A reduction in total bycatch biomass was also recorded for both grid models (85 % for a grid angle of 50° and 61 % for a grid angle of 32°), with no significant reduction in target species when using grid angle of 32°. The extensive testing performed supports the ecological benefits of BRDs adoption and tools for management in small scale fisheries.

Effect of dietary β‐carotene supplementation on growth and antioxidant capability of female swimming crab Portunus trituberculatus

AbstractDietary supplementation with synthetic β‐carotene was investigated in this study to assess its impact on gonad development, antioxidant status, color parameters, and carotenoid composition in adult female swimming crab (Portunus trituberculatus). Four diets, designated as Diet 1 to 4, were formulated to contain 3.07, 53.78, 103.23, and 205.22 mg/kg dry diets of synthetic β‐carotene. The findings revealed the following: (1) No significant differences in body weights or feed utilization were observed, indicating that β‐carotene did not significantly enhance the growth of adult P. trituberculatus. (2) The inclusion of 50–100 mg/kg β‐carotene in the diets led to improvements in antioxidant capacity indicators (T‐AOC, MDA) and immune‐related parameters (AKP, ACP) in both hepatopancreas and hemolymph. (3) Notably, the redness of ovaries and hepatopancreas increased significantly with higher dietary β‐carotene supplementation for color enhancement. In conclusion, incorporating β‐carotene into the diet enhanced the antioxidative capability, nonspecific immunity, and tissue carotenoid contents in adult female P. trituberculatus, and the optimal level of dietary synthetic β‐carotene supplementation for adult female P. trituberculatus was suggested to be around 100 mg/kg.

The impact of noise on the stress response of Portunus trituberculatus in a land-based monoculture system

Human-induced noise, particularly from shipping and construction, significantly affects the stress responses of swimming crabs (Portunus trituberculatus Miers, 1876). Prolonged exposure can lead to stress responses, impacting the overall health of the crabs. This study aimed to assess how noise affects stress responses in P. trituberculatus. The sound had an intensity of 163 dB 1μPa for the noise condition and 114 dB 1μPa for ambient sound. P. trituberculatus was continuously exposed to the noise stimulus for six hours. Samples of serum, muscle tissue, gills, and hepatopancreas were collected at multiple time points: 0 min, 10 min, 30 min, 1 h, 3 h, 6 h, and 7 h. The serum cortisol levels in the noise-exposed group were significantly higher than those in the control group at 30 min and 6 h. The two groups had no significant differences regarding serum glucose and muscle lactic acid content. In the noise-exposed group, the gills exhibited significantly lower superoxide dismutase (SOD) levels. Conversely, for the hepatopancreas, the SOD levels in the noise-exposed group were notably lower than those in the control group at 10 min but significantly higher at 6 h and 7 h. Malondialdehyde (MDA) levels were substantially higher in the noise-exposed group than in the control group at 30 min and 6 h. This study demonstrates that P. trituberculatus experiences a physiological stress response to acoustic sounds.

When neighbors become family: the dear-enemy effect of swimming crab and the verification of the formation hypothesis

When neighbors become family: the dear-enemy effect of swimming crab and the verification of the formation hypothesis

Growth, Development and Survival Rate of The Blue Swimming Crab (Portunus pelagicus) Cultured using Different Larvae Feeds

Blue swimming crab (Portunus pelagicus) is one of the most important commodities of softshell industry. Besides mud crab its demand as feed is increasing day by day. As a coastal dominant country, Bangladesh has a great feasibility of this species in culture, production, use and export. However, the production contribution from Bangladesh is still from natural sources and far behind in terms of farming, culture and production. Optimization of larval rearing techniques is therefore important to develop intensive hatchery rearing technique for this species. So, this study is aimed to develop larvae production technique of Portunus pelagicus with a better survival rate. Newly hatched first zoeal of Portunus pelagicus were reared using three different diets till second zoeal stage: (Treatment 1= Artemia franciscana umbrella + Rotifer (Brachionus rotundiformis); Treatment 2= Rotifer (B. rotundiformis) and Treatment 3= Artemia franciscana umbrella). Then, Artemia franciscana nauplii were used for all three treatments till they metamorphosed to crab instar. Regularly, water quality parameters were monitored and maintained and the survival and molting to next stages was observed. The result showed that, all the hatched zoea of P. pelagicus could successfully turns into crab instar stage under all the treatment applied, but the highest survival rate 6.08% was found in case of treatment 2 followed by 0.58%, 0.91%, respectively in treatment 1 and 3. In terms of metamorphosis, it took more than 15 and 14 days respectively from zoea 1 to metamorphose into megalopa for treatments 1 and 3, whereas metamorphosis from zoea 1 to megalopa in treatment 2 finished at the 12th day with a higher Larval Stage Index (LSI) value which was 4.9. Finally, at the 15th day larvae were metamorphosed into crablet for treatment 2 and 18 and 16 days required for metamorphosis into crablets for treatment 1 and 3, respectively. However, the larval feed showed a significant effect on growth and survival of P. pelagicus larvae, whereas the earlier larval stage of P. pelagicus rearing with Rotifer (B. rotundiformis) is found as the most suitable diet.

Reassembly and biotic sources of carapace bacterial community of Portunus trituberculatus after host molting

Crustaceans molt repeatedly during their development, which leads to frequent reassembly of their associated microbial communities. However, the reassembly of the carapace bacterial community (CBC) and its sources remain largely unclear. Here, these concerns were explored by investigating the succession pattern, assembly processes, and biotic sources of CBC of the swimming crab Portunus trituberculatus after host molting. Rhodobacteraceae, significantly discarded with the molted hard shell, was recruited during the 72 h postmolt. The early colonists such as Pseudoalteromonadaceae and Oeanospirillaceae had the higher physiological functional potentials for colonization, mainly via homogeneous selection. By contrast, the late colonists such as Flavobacteriaceae and Pseudomonadaceae had higher metabolic potentials and their colonization was governed by drift first and dispersal limitation later. The CBC was primarily shaped by multiple colonist pools, especially preceding carapace bacteria. Seawater had a higher contribution for CBC at the early stage than the late stage via providing the key bacteria mainly Rhodobacteraceae. These findings advance our understanding of the CBC and its reassembly pattern and sources, highlighting the importance of seawater bacteria for the early colonists. We also suggest the possibility and potential timing of using probiotics in the rearing water for the management of carapace microbiota in the aquaculture practice.

Selectivity of crab pots with escape vents and the optimal vent height for reducing the catch of sublegal swimming crab in the East China Sea pot fishery

Catching and subsequent discarding of sublegal-sized swimming crab Portunus trituberculatus in the pot fishery may result in increased unaccounted fishing mortality and contribute to overexploitation of the crab stocks in the East China Sea. Developing technical measures and implementing related regulations to improve the size selection of pots to reduce the catch of sublegal crab has become urgent. In this study, we evaluated the size selectivity of pots with rectangular escape vents of different opening heights (25 mm, 28 mm, 30 mm and 33 mm) through comparative fishing experiments and by employing the SELECT model. The results show that the installation of escape vents significantly reduced the catch per pot (in numbers) of total and sublegal swimming crabs, and significantly increased the proportion of legal-sized crabs for most vented pots except the 25 mm vent height. A significant positive linear relationship was found between escape vent height and the 50% retention carapace width, selection range and fishing power. Increasing the height of the escape vent had substantial effect on the exploitation pattern for swimming crab and the pot with a 28 mm height escape vent seemed to be the optimal design, releasing 67.4% of sublegal-sized crab and maintaining 94.8% of legal-sized crabs. Results showing that a pot with an escape vent that significantly reduces sublegal crab catch, while maintaining catch efficiency for legal-sized crabs, is positive for the fishery and supports the implementation of escape vents in the East China crab pot fishery.

Evaluation of spray-dried blood meal for application in commercial-like feed for juvenile swimming crab (Portunus trituberculatus)

The objective of the present study was to evaluate the effects of replacing fish meal (FM) with spray-dried blood meal (SDBM) on growth performance, antioxidant capacity, digestive enzyme activity, tissue Fe content, gene expression related to inflammation, and the TOR pathway in juvenile swimming crab (Portunus trituberculatus). Four isonitrogenous (47.0% protein) and isolipidic (9.0% lipid) diets were formulated to contain different levels of SDBM, with FM replaced by SDBM at 0, 10%, 20%, and 30%, respectively. The results showed that crabs fed diet SDBM30 exhibited the lowest survival among all treatments, and crabs fed the SDBM20 diet had the highest final weight, percent weight gain, specific growth rate and feed efficiency among all treatments. In addition, the protein content of the crab hepatopancreas decreased significantly and the lipid content increased significantly as SDBM replaced FM in the diets. Compared to other diets, crabs fed the SDBM30 diet had the lowest activities of antioxidant enzymes and the highest concentration of malondialdehyde in the hepatopancreas and hemolymph. The Fe contents in hepatopancreas and gill increased significantly, and the color of the hepatopancreas got darker as replacement of FM with SDBM increased from 0% to 30%. The expression of genes related to TOR (tor, akt, s6, and s6k1) and antioxidant (gpx) pathways in the hepatopancreas were down-regulated significantly with increased replacement of dietary FM with SDBM. In contrast, expression levels of genes related to protein translation (4ebp1, eif4e1a, eif4e2, and eif4e3) and inflammation pathways (myd88, traf6, relish, and irak4) were up-regulated significantly in crabs fed diets with SDBM supplementation. In summary, replacing FM with less than 20% of SDBM can promote the growth, but can darken the hepatopancreas, negatively affect antioxidant capacity, and induce an inflammatory response.

Combined effects of pentachlorophenol and nano-TiO2 with different sizes on antioxidant, digestive, and immune responses of the swimming crab Portunus trituberculatus

Marine nano-titanium dioxide (nano-TiO2) and pentachlorophenol (PCP) pollution are escalating concerns in coastal areas. This study investigated the combined effects of continuous exposure to nano-TiO2 (25 nm, 100 nm) and PCP (0, 1, 10 μg/L) for 28 days on the antioxidant, digestive, and immune abilities of the swimming crab Portunus trituberculatus. Compared with the control group, the interaction between nano-TiO2 and PCP was significantly higher than exposure to a single stressor, with a pronounced decrease in amylase activity observed due to the reducing nano-TiO2 particle sizes. Resulting in increased MDA and SOD activity. The expression levels of Toll4, CSP3, and SER genes in crab hemolymph showed perturbations following exposure to nano-TiO2 and PCP. In summary, according to the results of CAT, GPX, PES and AMS enzyme activities, it was concluded that compared to the larger particle size (100 nm), the single stress of nano-TiO2 at a smaller particle size (25 nm) and co-stress with PCP have more significant impacts on P. trituberculatus. However, the potential physiological regulation mechanism of the interaction between these pollutants remains elusive and requires further study.

Karakteristik Biologi dan Kelimpahan Rajungan (Portunus pelagicus) di Sekitar Perairan Sumenep

The high demand for the crab export market has resulted in the crab commodity experiencing a decline and leading to exploitation. Prediction of crab stocks in Sumenep Regency is minimal due to a need for further information regarding crab data. This study aims to determine the biological characteristics of the blue swimming crab (Portunus pelagicus), limiting blue swimming crab (Portunus pelagicus), and water quality characteristics around Sumenep. Research methods is observation methods or directly contact fishermen. Data collection included blue swimming crab biology, including morphometric aspects, which consisted of measurements of carapace width, carapace length, weight, and level of gonadal maturity. Data collection for water quality parameters used the insitu method at each research location. The results of this study were variations in the morphometric characters of the crabs in the distribution of the carapace width of the male crabs found in class 121-138 mm, as many as 137 individuals, while the female crabs were found in class 121-138 mm as many as 136 individuals, the distribution of size class based on the length of the female crab in class 60 .42-68.42mm as many as 112 people. The size class distribution of male crabs was mainly found in the 51.42-59.42mm class of 96 individuals; the distribution of size classes based on the weight in male crabs in the 126-157 gram class was 65 individuals. The size class of female swimming crabs was found in the 158-189 gram class; as many as 67 individuals applied for crabs around Sumenep. Based on the crab data collection at the first location, Talango was 289 ind/700 cm2, the second location was Tanjung Saronggi, 65 and/700 cm2, and in the third location, Gili Genting, there was as much as 104 ind/700 cm2. The waters of Tanjung Saronggi are a location that has more male crabs than female crabs. The air quality characteristics around Sumenep waters are categorized as optimal for blue swimming crab habitat.

Protein and lipid nutrition in crabs

AbstractUnderstanding the nutrition of crabs has a key role in ensuring the success and sustainability of their culture, as providing a well‐balanced, cost‐effective and sustainable diet that ensures the survival, growth and health of crabs is crucial. The present review is the first to focus primarily on the current state of knowledge of the nutrient requirements and related nutritional aspects in farmed crab species. The most common farmed and studied crabs are the Chinese mitten crab (Eriocheir sinensis Milne‐Edwards, 1853), giant mud crab (Scylla serrata Forsskal, 1775), green mud crab (Scylla paramamosain Estampador, 1949) and swimming crab (Portunus trituberculatus Miers, 1876). The article reviews how levels of dietary protein and lipid, the two most important and expensive macronutrient ingredients for most marine animals, directly affect reproduction, growth performance and survival of crabs, and the important impacts they have on immune response and antioxidant capacity. Furthermore, essential amino acids, and essential fatty acids, especially the long‐chain polyunsaturated fatty acids, as well as key lipid classes such as cholesterol and phospholipid will be discussed in terms of dietary requirements. Nutrient digestibility is a crucial method to determine protein quality, and studies on this topic in crabs were covered. The replacement of fishmeal and fish oil, as the predominant ingredients traditionally used in aquafeeds for marine animals, with more sustainable alternatives in diet formulations for crabs are also discussed. Modern ‘omics’ studies and high‐throughput technologies as fast‐growing approaches in protein and lipid research are also covered. Crabs generally require approximately 35%–50% protein, 5%–10% lipid, ~2.5% arginine, ~2.5% lysine, 1.5%–2.5% phenylalanine, 2.2% leucine, 0.7% tryptophan, 0.7% taurine, 1%–2% each of eicosapentaenoic acid, docosahexaenoic acid and arachidonic acid, 1% cholesterol and ~2% phospholipid in their diets.

Abstract 1101 Enhancing the reproductive capacity of female blue swimming crabs, Portunus pelagicus through hormonal manipulation and its potential for implementation in aquaculture

Abstract 1101 Enhancing the reproductive capacity of female blue swimming crabs, Portunus pelagicus through hormonal manipulation and its potential for implementation in aquaculture

Ghost fishing efficiency in swimming crab (Portunus trituberculatus) pot fishery

Abandoned, lost, or otherwise discarded fishing gear (ALDFG) is a global challenge that negatively affects marine environment through plastic pollution and continued capture of marine animals, so-called “ghost fishing”. In different pot fisheries, ghost fishing related to ALDFG is of concern, including pot fishery targeting swimming crab (Portunus trituberculatus). This study quantified the ghost fishing efficiency by comparing it to the catch efficiency of actively fished pots of the commercial fishery. The results showed that the ghost fishing affects both target and bycatch species. On average, the ghost fishing pots captured 12.53 % (confidence intervals: 10.45 %–15.00 %) undersized crab and 15.70 % (confidence intervals: 12.08 %–20.74 %) legal-sized crab compared to the actively fished pots. Few individuals of several bycatch species were also captured by ghost fishing pots. The results of this study emphasized the need to develop new management strategies for reducing marine pollution by ALDFG and associated negative effects in this pot fishery.

Changes in the physicochemical characteristics and microbial community compositions of the abdomen and cheliped muscles in swimming crab (Portunus trituberculatus) during frozen storage

The physicochemical indexes and microbial diversity were investigated to compare the altered quality properties of the abdomen and cheliped muscle in swimming crab (Portunus trituberculatus) during 100 days of frozen storage at −20℃. Over the extended duration of frozen storage, the sensory evaluation, moisture content, water activity (Aw), and water-holding capacity (WHC) in the abdomen and cheliped muscles of swimming crab decreased, while the pH, total volatile basic nitrogen (TVB-N), and trimethylamine (TMA) increased. The increase and decrease rates of these indicators were smaller in the abdomen than those in the cheliped muscle. High-throughput sequencing results indicated a reduction in the microbial richness and diversity in the abdomen and cheliped muscles of the swimming crab as frozen storage time extended. Proteobacteria, Actinobacteriota, and Firmicutes, Achromobacter, Kocuria, and Staphylococcus were the dominant phylum and genus in both muscle tissues, respectively. Furthermore, the correlation analysis between the composition of the microbiota and physiochemical properties revealed that the growths of Kocuria, Vibrio, Staphylococcus, and Aliiroseovarius were closely related to the physiochemical factors. The study provides a theoretical reference for quality deterioration and develops new products of different parts in the swimming crab during frozen storage.

Characterization of a pseudohemocyanin gene (PtPhc1) and its immunity function in response to Vibrio parahaemolyticus infection in the swimming crab Portunus trituberculatus

Pseudohemocyanin is a member of the hemocyanin superfamily, but little research is available on its function in immunology. In this study, a Portunus trituberculatus pseudohemocyanin gene, named PtPhc1, was obtained by gene cloning. The PtPhc1 cDNA was 2312 bp in length, encoding 684 amino acids while exhibiting a characteristic hemocyanin structural domain. Tissue expression analysis revealed ubiquitous expression of PtPhc1 across all tissues, with the highest level of expression observed in the hepatopancreas. The expression pattern of PtPhc1 in response to Vibrio parahaemolyticus infection was clarified using RT-qPCR in swimming crabs. Notably, the expression peaked at 24 h, and increased 1435-fold compared to the control group in the hepatopancreas. While the expression level reached the maximum value at 72 h, which was 3.24 times higher than that of the control group in hemocytes. Remarkably, the reduction in PtPhc1 expression led to a noteworthy 30% increase in the mortality rate of P. trituberculatus when exposed to V. parahaemolyticus. In addition, in vitro bacterial inhibition assays exhibited a dose-dependent suppression of bacterial proliferation by recombinant PtPhc1 protein, with a notable inhibition rate of 48.33% against V. parahaemolyticus at a concentration of 0.03 mg/mL. To the best of our knowledge, the results establish the function of pseudohaemocyanin in immunity for the first time, contributing to a deeper comprehension of innate immune regulatory mechanisms in aquatic organisms and advancing strategies for disease-resistant breeding.

The combined effects of microplastics and bisphenol-A on the innate immune system response and intestinal microflora of the swimming crab Portunus trituberculatus

Microplastics (MPs) and bisphenol-A (BPA) have been shown to have toxic effects on aquatic organisms. However, data on the combined effects of MPs and BPA on the innate immune system response and intestinal microorganisms of crabs are limited. Here, Portunus trituberculatus were exposed to BPA (at a concentration of 100 μg/L), MPs (microbeads of polystyrene with a particle size of 1 µm and at a concentration of 1 × 106 particles/L) or BPA+MPs for 21 days were tested at the tissue, cellular, and molecular levels. The results showed that neither the single nor combined exposure of MPs and BPA had a significant impact on the growth of crabs. However, intestinal histology study found that the intestinal villi of crabs in the BPA treated group, MP treated group and MP+BPA treated group appeared abnormal. Overall, compared with the control group and the single pollutant exposure group, co-exposure to the MP and BPA generally led to a significant increase in MDA and SOD activity and a significant decrease in CAT activity, and the activation of MyD88, Crustin-1, TARF6, Cu/Zn-SOD, Lyz, Toll-2 and NOX gene expression levels were significantly up-regulated. Co-exposure induced disorders of the intestinal microbial community of crabs, resulting in an increase in the abundance of harmful bacteria and a decrease in the abundance of beneficial bacteria. This study shows that the combined exposure of MPs and BPA can exacerbate the intestinal toxicity of a single pollutant to P. trituberculatus.

Dietary tributyrin supplementation promotes the growth by improving intestinal digestive and antioxidant capacity and the abundance of intestinal beneficial bacteria for swimming crab (Portunus trituberculatus)

This study aimed to evaluate the effects of tributyrin (TB) supplementation on the growth, digestive enzyme activity, lipid metabolism, and intestinal health of swimming crab (Portunus trituberculatus) with an initial weight of 12.50 ± 0.02 g. Six experimental diets were formulated, which containing 0%, 0.025%, 0.05%, 0.10%, 0.20%, and 0.40% of TB, respectively. Results showed that crabs fed the diet containing 0.10% TB had significantly higher values of percent weight gain (PWG) and specific growth rate (SGR) than those in other treatments. Crabs fed the diet without TB supplementation showed dramatically higher contents of T-CHO, TG, and MDA in serum than those in other treatments, opposite patterns were recorded for the activities of T-SOD, PPO, NO, ACP, and AKP. The activities of antioxidant enzyme including T-AOC, T-SOD, ACP, AKP and GSH-Px in hepatopancreas were significantly affected by dietary TB levels. Meanwhile, crabs fed the diet without TB supplementation had significantly lower activities of trypsin, lipase, and amylase in the intestine than those in other treatments. The relative expression levels of genes related to antioxidant capacity in the hepatopancreas and intestine were markedly decreased when crabs fed the diet without TB supplementation; however, crabs fed the diet without TB supplementation exhibited the highest expression of genes linked to inflammation among treatments, and the expression levels of crustin and lyso in the intestine were significantly affected by dietary TB levels. The expression levels of genes related to energy metabolism and intestinal immune barrier in the intestine were also influenced by dietary TB levels. Dietary TB supplementation could reduce lipid accumulation in hepatopancreas by upregulating lipid catabolism related genes expression levels and decreasing lipid anabolism related gene expression levels. Muscularis thickness, fold width, and fold height in the intestine were significantly increased with dietary TB increasing from 0% to 0.10%; moreover, lipid droplets, the diameter of R cells and the area of R cells in the hepatopancreas significantly decreased with an increase of dietary TB levels. Additionally, the number of Actinobacteria and Bacteroides significantly increased with an increase of dietary TB levels. To sum up, the TB requirement of swimming crab was 0.089% based on two slope broken-line analysis of PWG. The findings of the current study indicate that TB is an effective growth promoter that can serve as a nutritional supplement to improve the growth performance, promote health and regulate lipid metabolism of swimming crab.

Assessing the sustainability of the blue swimming crab (Portunus pelagicus) on the Eastern Coast of Lampung: a holistic approach to conservation and resource stewardship

In response to the escalating demand for blue swimming crabs (BSC) and the consequential impact on their habitat and population, this study advocates for sustainable management through a holistic approach. Our comprehensive framework integrates ecological conservation, socioeconomic well-being, and governance principles, aiming to establish a policy framework for the sustainable management of BSC in the Eastern Coast of Lampung. The research emphasizes the urgent issue of overexploitation, with an exploitation rate of 0.71, requiring immediate attention to prevent stock depletion and maintain ecosystem health. Findings reveal that male BSC, measured by carapace width, typically reaches the length at first catch (Lc50) at approximately 118.69 mm, while for females, it is about 122.70 mm—indicating that BSC is often caught larger than the 10 cm legal requirement set by the Ministry of Marine and Fisheries of Indonesia. Economic analysis demonstrates the profitability of the blue swimming crab business on Lampung's east coast, with a favorable crab capture per trip (4.63) and total costs ratio (1.18). The study area, featuring an extensive mangrove forest, hosts a crucial crustacean population, contributing significantly to BSC's diet. Beyond ecological significance, mangrove conservation enhances our understanding of environmental sustainability, particularly in carbon stock contributions. Addressing sustainability challenges requires a multi-faceted approach, including precise fishing technologies, effective regulation enforcement, and improved monitoring. Collaborative efforts among government authorities, fishing communities, and conservation groups are essential for balancing economic interests with the long-term ecological health of BSC populations in the study area.

Insights into sequence characteristics and evolutionary history of DGATs in arthropods

Triacylglycerol (TAG) is crucial in animal energy storage and membrane biogenesis. The conversion of diacylglycerol (DAG) to triacylglycerol (TAG) is catalyzed by diacylglycerol acyltransferase enzymes (DGATs), which are encoded by genes belonging to two distinct gene families. Although arthropods are known to possess DGATs activities and utilize the glycerol-3-phosphate pathway and MAG pathway for TAG biosynthesis, the sequence characterization and evolutionary history of DGATs in arthropods remains unclear. This study aimed to comparatively evaluate genomic analyses of DGATs in 13 arthropod species and 14 outgroup species. We found that arthropods lack SOAT2 genes within the DGAT1 family, while DGAT2, MOGAT3, AWAT1, and AWAT2 were absent from in DGAT2 family. Gene structure and phylogenetic analyses revealed that DGAT1 and DGAT2 genes come from different gene families. The expression patterns of these genes were further analyzed in crustaceans, demonstrating the importance of DGAT1 in TAG biosynthesis. Additionally, we identified the DGAT1 gene in Swimming crab (P. trituberculatus) undergoes a mutually exclusive alternative splicing event in the molt stages. Our newly determined DGAT inventory data provide a more complete scenario and insights into the evolutionary dynamics and functional diversification of DGATs in arthropods.

Larval Dispersal Modelling of the Blue Swimming Crab Portunus pelagicus (Linnaeus, 1758) from the Crab Banks along the Coast of Trang Province, Southern Thailand

In Thailand, the populations of a commercially important crab Portunus pelagicus (Linnaeus, 1758) have been decreasing due to overfishing, raising concerns about the conservation efforts of this crab species. The Crab Bank Project has recently been established to restore crab populations by releasing crab larvae from each crab bank station. However, the fate of crab larvae after the release is poorly understood. Here, we assessed the dispersal and settlement patterns of the larvae P. pelagicus released from crab banks along the coast of Trang Province, Southern Thailand. The Lagrangian particle tracking model was employed to simulate the larval dispersal and settlement patterns after release from the crab banks during the inter-monsoon, southwest monsoon, and northeast monsoon. Our simulation revealed that virtual larvae were predominantly retained within inshore areas after the release for 14 days, regulated by tidal-driven currents, wind-induced currents, and local coastal topography. Monsoon periods affected the larval dispersal, with some larvae being transported into estuaries due to the SW monsoonal effects. After the 14-day release period, our modelled simulations suggested that the crab larvae arrived at numerous seagrass meadows along the coast, indicating potential settlement and growth. This result highlights the connectivity of sources and sinks for crab larvae after release from crab banks. Moreover, significant implications for conservation efforts and the fishery management of P. pelagicus were also discussed based on our modelled simulations.