Scylla Olivacea Research Articles

Stock status and spawning potential ratio of orange mud crab (Scylla olivacea, Herbst 1796) in the southwestern coastal waters of Bangladesh

Scylla olivacea (Orange mud crab) is a second commercial invertebrate species exported from Bangladesh. Though a significant portion of exports are supported by aquaculture, their farming ultimately depends on their wild stocks. Unfortunately, unregulated exploitation has led to a significant decline in the natural biomass of this species, raising concerns about the sustainability of crab production in Bangladesh. The study aimed to assess the stock status of S. olivacea (Orange mud crab) from the Southwestern coastal water of Bangladesh. One-year length frequency (width frequency-WF for crustacean fishery) data were collected and analyzed using the LBB (Length-based Bayesian Biomass) and LB-SPR (Length-based spawning potential ratio) methods. The assessed width parameter depicted the exploitation of small-size individuals (Wc=< Wc_opt) of S. olivacea. The estimated B/B0 (0.25) suggests that 75 % of the wild stock had already been harvested, and biomass cannot produce MSY. The mean estimates for SW50 % and SW95 % were 8.29 cm and 12.76 cm respectively, revealing the use of a small mesh-size net for crab harvesting. The assessed Spawning Potential Ratio (SPR) was 12 % which is below the SPR limit reference point (SRP) of 20 %. This research confirmed the overfished (F/M = 1.4) and overexploited (E = 0.58) status of S. olivacea in Bangladesh. To ensure the sustainability of coastal fisheries in Bangladesh, the authorities must take immediate management measures to control the overexploitation of this species.

Stock assessment of the mud crab (Scylla olivacea) collected from the terrestrial edge of the Sundarbans mangrove forest, Bangladesh

We estimated mud crab (Scylla olivacea) population parameters to determine recruitment patterns, asymptotic carapace width (CW∞), growth coefficient (k), mortality rate (Z, M, and F), exploitation rate (E) and relationship between body weight and carapace width (BW - CW) in the terrestrial edge of the Sundarbans mangrove forest, Bangladesh. Baited long lines and traps were used to collect crab samples from the terrestrial edge of the mangroves (up to 10 km inside of the Sundarbans mangroves) monthly for a year (Jan 2021–Dec 2021). These CW frequency data were utilized to determine population characteristics. Based on the BW × CW relationship, male S. olivacea crabs increased their BW faster (b = 2.89, R2 = 0.86) than females (b = 2.29, R2 = 0.82). Crabs displayed negative growth allometry, b significantly differed from the isometric growth (b = 3). Both male and female CW∞ was estimated to be 126.00 mm and 113.40 mm, with k values of 0.50 yr−1 and 0.48 yr−1, respectively. The total mortality (Z), natural mortality (M), and fishing mortality (F) of male and female crabs were 1.89 yr−1 and 1.84 yr−1, 0.79 yr−1 and 0.80 yr−1 and 1.10 yr−1 and 1.04 yr−1 respectively. Both sexes were recruited using a bimodal recruitment strategy, with a significant peak from March to June. However, young crabs were present year-round. The virtual population analysis (VPA) shows that males and females are caught at smaller sizes (60–90 mm). The estimated exploitation rate (E) exceeds (0.58 for males and 0.57 for females) the optimum exploitation level (E = 0.50) and E values were close to the projected maximum yield per exploitation rate (Emax = 0.655 for males and 0.647 for females) which indicated over-exploitation of the mud crabs from the territorial edge of the Sundarbans mangrove forest of Bangladesh and hence suggested for proper management.

Hydroxyapatite synthesis and characterization from marine sources: A comparative study

BackgroundHydroxyapatite (HAP) is a biocompatible material widely used in biomedical applications. Recent studies have explored various marine sources for HAP synthesis, demonstrating its potential for diverse applications. ObjectiveThis study aims to compare the characteristics of hydroxyapatite synthesized from sea shells and fish bones, specifically from the shells of Scylla olivacea (orange mud crab) and bones of Eleutheronema tetradactylum (fourfinger threadfin). Materials & methodsHAP was synthesized from Scylla olivacea shells and Eleutheronema tetradactylum bones. The synthesized HAP underwent comprehensive characterization, including scanning electron microscopy (SEM) for structural analysis, hemocompatibility testing, antibacterial assays, and energy-dispersive X-ray spectroscopy (EDS) analysis. ResultsSEM revealed a complex structure of HAP with a clustered arrangement and biofilm-like features. HAP derived from crab shells exhibited superior structural properties compared to that from fish bones. Both sources demonstrated good hemocompatibility, essential for biomedical applications. The antibacterial assays indicated effective antibacterial properties for both HAP sources, with crab shell-derived HAP showing slightly better performance. EDS analysis confirmed the presence of key elements necessary for HAP, with a consistent composition in both sources. ConclusionOur study concludes that hydroxyapatite derived from Scylla olivacea shells exhibits superior properties compared to that from Eleutheronema tetradactylum bones. This research establishes a precedent for future investigations into other marine species, thereby broadening the scope and potential of hydroxyapatite synthesis from natural sources.

Nutritional prospects and heavy metal risks in fattened versus wild mud crabs of the Ganges-Brahmaputra delta: Implications for sustainable management

Scylla olivacea, or the mud crab, is a crucial economic contributor in Southeast Asia, notably in the coastal region of the Ganges-Brahmaputra delta. This study compared the nutritional and heavy metals of fattened and wild-captured mud crabs from the southwest coastal areas of the Ganges-Brahmaputra delta, focusing on proximate composition, fatty acids, amino acids, and heavy metals. Fattened mud crabs showed higher crude protein levels (13.2%–14.4%), particularly in males, and higher crude fat and ash contents than their wild counterparts. Among fatty acids, fattened crabs had the highest palmitic acid levels (34.0%–41.2%), whereas wild crabs were rich in linoleic and linolenic acids. Amino acid analysis revealed that histidine and arginine were the most prevalent essential amino acids in fattened and wild crabs, respectively. Elemental analysis indicated that calcium levels were high in both groups. However, zinc, copper, iron, and manganese concentrations exceeded recommended dietary allowances. Furthermore, the wild mud crabs contained heavy metals lower than that of the fattened mud crabs. Notably, nickel, lead, and cadmium levels surpassed maximum permissible limits, suggesting potential health risks in fattened and wild mud crabs. The concentration of Omega-3 fatty acids was higher in wild crabs than in cultured ones. These findings emphasize the need for cautious consumption and strict monitoring in mud crab aquaculture to ensure food safety and sustainability.

Physiological adaptation and gut microbiota changes of orange mud crab Scylla olivacea in response to increased temperature condition

Physiological adaptation and gut microbiota changes of orange mud crab Scylla olivacea in response to increased temperature condition

Artificial insemination of mud crab, Scylla olivacea

Artificial insemination of mud crab, Scylla olivacea

The Effect of Various Levels of Protein and Carbohydrate in the Feed on the Carcass, Chemical Composition, and RNA/DNA Ratio of the Mud Crab (Scylla olivacea) in an Apartment System

The Effect of Various Levels of Protein and Carbohydrate in the Feed on the Carcass, Chemical Composition, and RNA/DNA Ratio of the Mud Crab (Scylla olivacea) in an Apartment System

The Effect of Various Levels of Protein and Carbohydrate in the Feed on the Carcass, Chemical Composition, and RNA/DNA Ratio of the Mud Crab (Scylla olivacea) in an Apartment System

The Effect of Various Levels of Protein and Carbohydrate in the Feed on the Carcass, Chemical Composition, and RNA/DNA Ratio of the Mud Crab (Scylla olivacea) in an Apartment System

Dietary lacto-sacc stimulates the immune response of gravid mud crab (Scylla olivacea)

Mud crabs have a functioning innate immune system. Probiotics have a considerable effect in improving immune responses in gravid mud crab. The current study investigated the influence of three lacto-sacc concentrations (T1=0 %, T2=1 %, and T3=1.5 %) in a 45 % protein and 12 % lipid meal on the immune response of gravid mud crabs. Three groups of wild gravid mud crabs (average weight: 122.33±1.53 g) were raised individually in bamboo spawning boxes at mangrove pens for 12 weeks. Wild gravid mud crabs (T4) were also caught from the river during the breeding season and tested to offer a more exact assessment of the effect of lacto-sacc. After a 12-week feeding study, T3 therapy resulted in the highest total hemocyte count levels (P < 0.05), followed by T2 and T1. The T3 treatment results in somewhat faster hemolymph clotting, although there is no significant difference among the treatments (P < 0.05). T3 treatments significantly improved immunological parameters (PO, proPO, and SOD enzyme) and survival (61.67±2.89 %) when challenged with Vibrio parahaemolyticus. In the challenge test, the immunological markers THC, PO, and proPO correlated positively, but hemolymph clotting time and mortality linked negatively. Furthermore, T1 was compared to an untreated wild gravid female mud crab (T4), and the results were almost identical. Thus, 1.5 % lacto-sacc is recommended for gravid mud crabs.

Ecotoxicological impact of heavy metals on wild mud crabs (Scylla olivacea) in Malaysia: An integrative approach of omics, molecular docking and human risk assessment

Mud crab, one of the aquatic organisms found in estuary areas, has become a significant economic source of seafood for communities due to its delectable taste. However, they face the threat of heavy metal contamination, which may adversely affect their biological traits. This study explored the comparison of the mud crabs collected from Setiu Wetland as a reference site, while Kuala Sepetang is an area that contains a higher concentration of heavy metals than Setiu Wetlands. Heavy metal levels were quantified using inductively coupled plasma mass spectrometry (ICP-MS), while proteomes were assessed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and 1H nuclear magnetic resonance (NMR)-based metabolomics, respectively. Heavy metal contamination affects the proteome, metabolome, and putative molecular targets in mud crabs (Scylla olivacea), leading to oxidative stress. Mud crabs collected from the metal-polluted area of Kuala Sepetang in Perak had considerably elevated concentrations of nickel (Ni), copper (Cu), zinc (Zn), lead (Pb), chromium (Cr), and cadmium (Cd) in comparison to the reference site of Setiu Wetlands in Terengganu. The proteome analysis revealed an upregulation of the stress-response protein Hsp70, which triggered superoxide dismutase (SOD) and increased arginine kinase expression (5.47 fold) in the muscle tissue, results in the alteration of metabolite regulation in the mud crab from Kuala Sepetang. Additionally, in the muscle tissues of mud crabs obtained from Kuala Sepetang, uncharacterized myosin-tail 1 domain proteins and sarcoplasmic calcium-binding proteins were downregulated. The metabolomic investigation identified changes in metabolites associated with energy metabolism and osmoregulation. Exploration of docking analysis suggests potential connections between methylarsonic acid and essential proteins in mud crabs. These findings suggest that the presence of heavy metals disrupts physiological processes and highlights potential molecular targets that warrant further investigation.

Quantification of heavy metals in wild gravid female mud crab (Scylla olivacea) collected from different rivers of Sundarbans mangrove region

Heavy metals pollution is one of our major problems in Sundarbans mangrove zone as we all their surrounding rivers. The presence of industrial development in the nearby areas of coastal and marine aquacultures sites are the cause of heavy metals pollution. The aim of the research was to quantify heavy metals in gravid female mud crabs (Scylla olivacea) in three different rivers of Sundarbans region. Mud crabs and their surrounding water and soil sediments were collected from Mongla, Kholpetua, and Kopotakkho rivers. Analysis of river water was conducted in the laboratory of Shiva Analyticals (India) Private Limited, India, whereas live mud crabs and sediment samples were analyzed from Quality Control Laboratory (QCL), Khulna, Bangladesh for the quantification of heavy metals. The results showed that the heavy metals As, Cr, Cd, Hg and Pb were detected in mud crabs and their surrounding river water and sediments, but the concentration of heavy metals in mud crabs was remains below the limit of human’s consumptions except the heavy metal Chromium (Cr). Maximum concentration of heavy metals was detected Kopotakkho river followed by Mongla and Kholpetua river. The concentration of heavy metals was highest in soil sediments followed by mud crabs and river waters. Mud crabs were contaminated by heavy metals that bioaccumulated from their surrounding sediments and water sources. The hierarchy of mean concentrations (mg/kg) of the heavy metals were Pb>As>Cr>Pb>Hg. Heavy metals are carcinogenic for human consumption when exceeded their permissible levels. It is urgent to stop pollution in Sundarbans mangrove zone and led to serve healthy foods for the nations.

Natural breeding performance in different saline water pens, crablets rearing and cannibalism in juvenile phase of mangrove mud crab (Scylla olivacea) in earthen mangrove pens

The current study focused on natural breeding techniques using locally available mud crab broods during breeding season. The breeding trial was tested in artificially created earthen pens that designed with mangrove plants and salt tolerance grass. Mature brood crabs were collected from local rivers and equally distributed in 20 L black color plastic containers in three different salinities (T1 = 24ppt, T2 = 26ppt, and T3 = 28ppt) and covered with black cloth. The river salinity was 26ppt during breeding season that is considered as control(T2), and treatment T1 and T3 were prepared artificially mixing with water and sea salt respectively. Broods are reared in containers until hatching and zoea was transferred to earthen pens immediately after hatching. Zoea were reared in earthen pens until turns to crablet(0.027 ± 0.005 g). The broods as well as crablet were identified through molecular barcoding and confirmed species as Scylla olivicea. Besides, morphometric characters like weight(126.22 ± 0.19 g), carapace length(6.36 ± 0.08 cm), carapace width(9.08 ± 0.08 cm), carapace color(brownish to brownish green), Anterolateral margin and teeth (3.79 ± 0.05 cm), abdomen length(3.04 ± 0.02 cm), hand (5.50 ± 0.03 cm), carpus(2.54 ± 0.04), antenna (2.69 ± 0.07), frontal margin(2.90 ± 0.07 cm), dactylus(3.13 ± 0.06 cm), thoracic sternites(4.17 ± 0.10), merus(4.16 ± 0.11 cm) etc. are also assessed during the experiment. The hatching rate, survival %, incubation period and other parameters are significantly different among the treatments. The highest hatching rate was observed in T2(91.34 ± 4.61 %) and lowest was in T1(57.98 ± 1.38) whereas the highest survival rate was recorded in T2(10.53 ± 1.56) and lowest observed in T1(2.87 ± 0.68). The order of incubation was T1(12.3 days)>T3(11 days)>T2(8.67days) observed during experiment. The cannibalism rate was also estimated in this experiment and observed cannibalism rate was 71.20 ± 2.08. Natural mud crab breeding is easy and can be applicable in fields at low cost with significant survival rate.

Collection Practices and Socio-Economic Status of Crab Collectors at Shyamnagar Upazila, Satkhira Distrct in Bangladesh

This study evaluated the mud crab (Scylla olivacea) collection techniques and socio-economic conditions of crab collectors in Shyamnagar Upazila. The results showed that 48% of the collectors collected crabs from the Sundarbans mangrove forest; on the other hand, 42% of the crab collectors collected crabs from coastal rivers, and 10% collected crabs from canals and shrimp farms. In the study area, 63% of crab collectors used doon with Cuchia fish as bait, 6.66% used thopa with Tilapia fish as bait, and the rest used net or hand-picking techniques to collect crabs. Most crab collectors were Muslims (56.9%), and the rest were Hindu (43.1%) regarding religious belief. Regarding gender, 58.1% of crab collectors were female, whereas 41.9% were male. Almost half of crab collectors (41.9%) had no institutional education. In this area, 33.72% were landless and lived on ‘Khas’ land. A significant number of people (29.5%) were married at an early age. The crab collectors (36.2%) earned less than Tk. 200 daily. Natural calamities and other constraints are making the livelihood of crab collectors vulnerable, but they are trying to continue their occupation to sustain their lives. Jagannath University Journal of Life and Earth Sciences, 9(1): 57–68, 2023 (June)

Moulting Performances Evaluation of Female Orange Mud Crab, Scylla olivacea (Herbst, 1796) In-Captivity: Effects of Water Salinity and Limb Autotomy.

Female Scylla olivacea has become more popular in Malaysia as emerging species mainly for soft-shell crabs and crab fattening (to increase weight, size and ovary maturation so that they can be sold at a higher price). To harvest crabs in soft-shell conditions and fattening, both conditions depend mostly on moulting events. To accelerate the moulting process, the manipulation of water parameter (salinity) and autotomy of the limb is commonly used. In this study, the evaluation of the moulting performances of full limb autotomy (the removal of all the appendages except for the swimming legs) and non-ablated (control) using immature S. olivacea cultured in three different salinity treatments (10 ppt, 20 ppt and 30 ppt) were performed. Results indicate there were significant differences between mud crab's culture duration, BW increments, growth performances and feeding efficiency with salinity. However, CW increments and survival indicate no significant effect with salinity. Meanwhile, limb autotomy proved to affect the culture duration, BW increments, survival and feeding efficiency of S. olivacea. The study concludes that both salinity and limb autotomy play significant roles in moulting performances of S. olivacea, with 20 ppt being the best salinity to stimulate S. olivacea moulting and development compared with the other two treatments (10 ppt and 30 ppt). Limb autotomy also indicates promising results as this technique proved to accelerate the moulting duration of S. olivacea with a 100% moulting percentage within 30 days. Therefore, the outcome would certainly benefit in the aquaculture production of this species of commercial importance mainly on soft-shell crabs production and also emerge as crabs fattening technique.

A comparative study on the antennae morphology and ultrastructure of three mud crab species of the genus Scylla from Setiu Wetlands, Terengganu, Malaysia.

Crustaceans possess a range of sensory organs crucial in sensory perception, communication, and various ecological functions. Understanding morphological and functional differences in antennae among species could validate taxonomic differentiation and ecological adaptations. The antennae morphology and ultrastructure of mud crab species within the Scylla genus are poorly understood, and their role in ecological adaptation and species differentiation remains unexplored. This study aimed to describe and compare the morphology and ultrastructure of antennae in Scylla olivacea, Scylla tranquebarica, and Scylla paramamosain. Antennae were carefully excised from each crab and subjected to morphological, morphometric, and ultrastructural analysis. The study revealed that the antennae of Scylla species exhibit similar overall morphology, with a series of segments that tapered toward the upper end. All species possess non-branched single setae on the upper end of each segment. The number of antennae segments varied between species, with S. paramamosain having significantly more segments than S. olivacea. Additionally, the length and width of antenna segments differed among the species, with S. tranquebarica having a rougher antenna surface compared to S. olivacea and S. paramamosain. Our findings suggest that Scylla's antennae are distinct between species, especially in the number of segments and setae size. Such difference might be related to ecological adaptation. The role of antennae in sensory perception and social behavioral cues in mud crabs warrants further investigation. This study serves as a foundational reference for future research on the taxonomy, ecological adaptation, and sensory behaviors in the Scylla genus. RESEARCH HIGHLIGHTS: Variations and similarities in morphology and ultrastructure of three Scylla species can be found in the antennae. Scylla paramamosain had significantly higher number of segments than Scylla olivacea in morphology feature. The antennae surface of Scylla tranquebarica was rougher than that of S. olivacea and S. paramamosain. Antennae of three Scylla species possess non-branched single setae.

Feasibility of rice-crab (Scylla olivacea) co-cultures in the south-west coastal ghers of Bangladesh

To assess the production performance in terms of growth, survival and intactness of mud crab in co-culture with rice plants an experiment was conducted for a period of 120 days in the ghers of two villages under Paikgacha Upazilla, Khulna. The crab juvenile was collected from adjacent Shibsha River and stocked in two experimental ghers of 0.004 ha area each without considering male female ratio. The stocking density was 50 per decimal, 75 per decimal, 100 per decimal in T1, T2 and T3 treatments of two experiments, respectively. Fresh chopped tilapia fish was fed to the crab and the requirement of supplied tilapia fish was adjusted periodically in accordance with the growth performance or body weight of crab. Production and physico-chemical parameters were recorded and analyzed according to standard methods. Among these parameters salinity had significant (p&lt;0.05) role on survival of mud crab. After 120 days of rearing we obtained average final weight of cultured crab (Scylla olivacea) was 154.6±12.19g, 135.46±21.30g and 107.23±14.87g; with the estimated yield of 995.96±193.43 kg/ha, 1179.4±266.68 kg/ha and 1144.22±544.05 kg/ha, survival was 45%, 47% and 42% in T1, T2 and T3 treatments respectively in Bayra village; On the other experimental site in Gopalpur village we obtained average final weight of cultured crab was 169.2±19.20g, 155.22±17.73g and 167.53±18.60g; with the estimated yield of 476.83±160.51 kg/ha, 793.73±361 kg/ha and 1636.19±868.32 kg/ha, survival was 25%, 27% and 22% in T1, T2 and T3 treatments respectively The yield of rice was found 6006±1021 kg/ha, 6026±991 kg/ha, 5995±1005 kg/ha in T1,T2,T3 treatments respectively in the experiment of Bayra village on the other hands in Gopalpur village the yield was 5877±1297 kg/ha, 5743±1350 kg/ ha, 5468±1190 kg/ha in T1,T2,T3 treatments respectively. Results and findings of the present study suggested that yield of rice was not hampered for rice-crab co-culture in ghers. According to the experimental results poor salinity level, temperature, water level fluctuation and winter seasons are the potential constraints in the growth, survival and intactness of rice crab co-culture in the coastal ghers of Bangladesh.

Plastic ingestion by three species of Scylla (Brachyura) from the coastal areas of Thailand

This study marked the first investigation into the presence of plastic particles in the stomachs of three mud crab species (Scylla olivacea, S. paramamosain and S. tranquebarica) collected across the Andaman Sea and the Gulf of Thailand. The highest number of plastic particles in the stomach of crab samples was polyethylene (PE) that contributed 88.5 %; while green was the predominant colour (60.3 %). Ingested particles recovered from the stomachs of crabs differed significantly between species and sites (p < 0.001). The average number of plastic particles per individual was 2.3 ± 8.6 in Scylla olivacea, 7.2 ± 16.9 in S. paramamosain, and 13.5 ± 48.9 in S. tranquebarica. Satun, revealed the highest number of plastic particles recovered from mud crabs, while the lowest number of plastic particles were from Pattani. To conclude, species of crab and site of collection plays a crucial factor in the propensity of plastic particles ingested by the genus Scylla mud crabs.

Indigenous craft and gears used for crab fishery in Cochin estuary, Kerala, southwest coast of India

This paper presents an overview of fishing gears and crafts operated for crab fishery in the Cochin estuary. A survey was made in selected areas of the Cochin estuary to study the design and operational details of indigenous craft and gears used in crab fishing. Primary data on crab fishery were collected from fish landing centers and fishing villages through a structured questionnaire. Crab gillnets and ring nets are the dominant artisanal gear supporting crab fishery throughout the study area. Long lines were one of the widely deployed fishing gears for the crab fishery, which is now operational only in limited areas of the Cochin estuary. Incidental catch of crabs is also noted in the stake net and Chinese dip net. The wounding gears and traditional fishing techniques, viz., vazhuka method and midrib trap, are not deployed in commercial crab fishery as they result in low-value realization. The survey discloses that ring net and crab gillnet accounted for 98% of the crab landing along the Cochin estuary. Scylla serrata and Scylla olivacea are the essential species contributing to inland crab fishery along the study area. Wooden canoes belonging to 3 to 7 m in length overall (LOA) are employed for crab fishing. Migrant fishermen use Coracles and the FRP canoes for crab gill net operations along the stretches of the backwaters.

Potent ovarian development as being stimulated by cocktail hormone in the female Scylla olivacea

The mud crab Scylla olivacea is widely cultured for its economic value, but reproduction issues limit its production. Vitellogenesis-inhibiting hormone (VIH), serotonin (5-HT), and gonadotropin-releasing hormone (GnRH) are important neurohormones that control reproduction in crustaceans. Mimicking crab hormone stimulation during reproduction has scarcely been reported. Comparison of the single hormone and multiple hormone approaches to crab hormonal control in S. olivacea is limited. In situ hybridization showed that injection of dsRNA-VIH could abolish its gene expression in neuronal clusters of female S. olivacea eyestalks, potentially reducing its inhibitory effects on ovarian maturation. This was confirmed by assessing the ovarian gonadosomatic index (GSI), hemolymph vitellogenin (Vg), an indicator of vitellogenesis, and gonad histology using dsRNA-VIH and 5-HT/GnRH combinations. Based on our findings, we demonstrated that administration of dsRNA-VIH significantly increased the gonadosomatic index (GSI) on days 14 and 28 post-treatment. The combination cocktail, however, consisting of 5-HT + GnRH + dsRNA-VIH on days 14 and 28, and GnRH + dsRNA-VIH on day 28, was the most efficacious in increasing GSI and enhancing crab ovarian maturation. Upregulation of hemolymph Vg levels was observed solely on the 28th day following treatment with dsRNA-VIH, 5-HT + GnRH + dsRNA-VIH, and GnRH + dsRNA-VIH. Differential gene expression analysis using quantitative RNA-sequencing of the neural tissues (brain and ventral nerve cord), revealed a significant upregulation of certain receptors (5-HTR, GnRHR, LHR, and FSHR), neuropeptides (sNPF, NPF1, NPF2, SIFamide, AKH/Crz, CHH, and RPCH), downstream reproductive-related genes (FAMeT, ESULT, progesterone-like protein), and prostanoid-related genes (phospholipase A and C, COX, Thromboxane A synthase, prostaglandin D, E, and F synthases) following treatment, particularly dsRNA-VIH + GnRH and/or 5-HT-injected individuals. Upregulation of prostaglandin E synthase and estrogen sulfotransferase genes was confirmed by real-time PCR. Since the construction and propagation of dsRNA-VIH is costly, its lower dose application supplemented with synthetic GnRH and/or 5-HT may be an alternative approach to ensure that female S. olivacea attain sufficient reproductive fecundity in aquaculture. Furthermore, we propose that the administration of multiple hormones in crabs may better emulate the physiological conditions of crustaceans in their natural habitat.

TELAAH ASPEK BIOLOGI KEPITING BAKAU (Scylla spp) TERTANGKAP DI AREAL EKOSISTEM MANGROVE KABUPATEN PASANGKAYUPROVINSI SULAWESI BARAT

The coastal area of Pasangkayu Regency, has the potential of mangrove crab resources, which have not been utilized optimally. This study aims to determine the species composition, and biological aspects of the mangrove crab Scylla spp caught in the Fold trap in the mangrove ecosystem area in Pasangkayu Regency, West Sulawesi Province, Indonesia. The research was carried out from March to June 2020. The materials used consisted of the Global Positioning System (GPS), Camera; and digital scales and rulers. Types of data collected include primary and secondary data. Primary data were collected from surveys and field observations, secondary data were collected from various related agencies. Data analysis includes species composition and biological aspects. The results of the identification of mangrove crabs found 2 types of mud crabs, Scylla serrata and Scylla olivacea, which were more dominant than Scylla olivacea. The results of the analysis of the biological aspect showed that the mangrove crab species were Scylla serrata in the allometric minor category and Scylla olivacea in the isometric category. The size distribution of long class frequencies, types of Scylla serrata and Scylla olivacea. The sex ratio of Sylla serrata is in the balanced category and Sylla olivacea is not balanced, the number of females is less than males. The rate of exploitation of the two types of mangrove crab Scylla serrata and Scylla olivacea is still rational and sustainable, the E value &lt;0.5% or the highest E value 0.5% is still considered sustainable. The conversion rate of mangrove ecosystems for various purposes needs to be reduced so that the mangrove crab habitat area is maintained.