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Mud crab has great demand globally, leading to extensive research that focuses on enhancing the crab survival in hatcheries. This study aimed to evaluate the optimal protein requirement of mud crabs during the transition from megalopa to the early instar stage. The megalopae were cultured in triplicate black containers (n = 30) and fed one of the five formulated diets containing 40%, 45%, 50%, 55%, or 60% dietary protein for 14 days. The growth, survival, and larval stage composition were evaluated on days 7 and 14. The percentage of crab instars 1 (C1) on day 7 (20.07 ± 3.43% to 41.63 ± 5.77%) and C2 on day 14 (47.37 ± 2.35% to 57.96 ± 5.67%) revealed an increasing trend from the 40% to 55% protein level treatments, however, the percentage decreased in the 60% treatment. Growth performance exhibited a similar increasing trend from 40% to 55%, declining at 60%. Enhanced growth with 55% protein was supported by the lowest food conversion ratio (P < 0.05) and highest protein and lipid efficiency ratio (P < 0.05). However, the results did not differ significantly with the group fed with 50% protein. A second-order polynomial regression on the growth performance suggested that 51.3% is required for best growth during the transition of megalopa larvae to the early instar stage. [ABSTRACT FROM AUTHOR]

The present study evaluated the potential of a saccharide mixture (galactose, glucose, fructose, and sucrose in a 2:1:1:1 ratio) as a chemoattractant (attraction) or/and feeding stimulant (ingestion) for the purple mud crab Scylla tranquebarica. In Experiment I, the S. tranquebarica appetitive response toward the 3%, 5%, or 7% (w/v) saccharide mixture solutions was examined and evaluated by a scoring method. The 5% and 7% treatments yielded the highest mean score (2.05 out of 3.00), with 20% of the S. tranquebarica exhibiting the highest response order (probing movement) in the latter treatment. In Experiment II, the S. tranquebarica feeding response toward the pelleted feeds containing the saccharide mixture at 3%, 5%, or 7% (SAC3, SAC5, or SAC7) was examined and evaluated using a scoring method. No significant difference (P > 0.05) was found among the mean scores of SAC3, SAC5, and SAC7. However, the mean score of the SAC7 diet was significantly higher (P < 0.05) than that of the control feed (without saccharide mixture inclusion), with 25% of the S. tranquebarica ingesting the feed. These findings highlight the potency of the saccharide mixture as a feeding effector for S. tranquebarica. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: Mangroves have high potential for advancing ecotourism because of their position at the intersection of land and sea. Many studies have reported that mangroves and coastal environments are the right places for the development of sustainable ecotourism. The aim of this study is to assess the tourism prospects of significant mangrove ecosystems in Sumatra, Indonesia, and to identify suitable approaches for fostering ecotourism. METHODS: The research was conducted in Beras Basah Village, located in the Pangkalan Susu District of Langkat Regency, North Sumatra, Indonesia. It commenced in November 2023 with the initiation of the Beras Basah ecotourism project and concluded in January 2024. The research commenced by introducing the ecotourism landscape through the utilization of a geographic information system. Subsequently, questionnaires and discussion group forums were employed to analyze the community, visitors, and relevant stakeholders. Furthermore, an assessment of the potential mangrove ecosystem was conducted, encompassing transects, ecological suitability, and carrying capacity. Lastly, a comprehensive analysis of the research findings was performed, focusing on the strengths, weaknesses, opportunities, and threats associated with the study. FINDINGS: The potential area for ecotourism covers 38 hectares with various well-designed facilities and infrastructures. The mangroves were utilized as a source of sustenance with the overall condition of community. This study obtained 8 species of mangroves consisting of Rhizophora apiculata, Rhizophora mucronata, Rhizophora stylosa, Sonneratia alba, Avicennia marina, Bruguiera gymnorrhiza, Xylocarpus granatum, and Scyphiphora hydrophyllacea. The species of fauna observed were two species of birds (Haliaetus leucogaster, Bubulcus ibis), three species of reptiles (Varanus salvator, Fordonia leucobalia, Mabouia multifasciata), three types of mammals (Macaca fascicularis, Tupaia glis, Martes flavigula), seven types of fish (Plotosus canius, Epinephelus lanceolatus, Ophiocara porocephala, Lutjanus argentimaculatus, Lates calcarifer, Scatophagus argus, Mugil cephalus), five types of mollusks (Cerithidea cingulata, Telescopium telescopium, Cerithidea quadrata, Murex trapa, Polymesoda bengalensis), and four types of crustaceans (Scylla serrata, Metapograpsus sp., Panaeus monodon, Panaeus merguensis). The two studied stations exhibited varying levels of ecological suitability. One approach to protection is the enforcement of a visitor quota based on the carrying capacity of the areas, was 86 individuals per day. Furthermore, the analysis of strengths, weaknesses, opportunities, and threats revealed that the improvement of mangrove ecosystem management, the addition of supporting facilities, and the provision of environmental and conservation education to tourists can contribute to the enhancement of ecotourism. CONCLUSION: Ecotourism plays a crucial role in preserving the sustainability of the mangrove ecosystem while also influencing socio-economic factors. Through study and analysis of both human behavior and natural processes, effective management strategies can be developed to support ecotourism initiatives. The findings of this study highlight the significance of ecotourism and emphasize the importance of expanding ecotourism initiatives, enhancing infrastructure, and promoting environmental awareness. [ABSTRACT FROM AUTHOR]

A value chain analysis (VCA) is a cost‐effective tool to guide targeted value chain development interventions to address social wellbeing and environmental performance. Examining value chains through a gender lens can help design and implement interventions that enhance opportunities for women in the fisheries and address gender inequalities in the sector. We conducted a VCA in 2015 of the wild‐caught mud crab (Scylla serrata) fishery in Bua Province, Fiji. We found five main players involved in the selling of mud crabs – fishers, traders, retail shops, restaurants and exporters. The value chain was dominated by Indigenous (iTaukei) women fishers (88.1% of fishers) and characterised by low technological input, targeted largely for domestic markets or consumption, and with limited value‐adding activities. Although most women harvested mud crabs on a part‐time basis, it was an important source of income for most with 30% relying on it as their main livelihood. Despite being a lucrative commodity, there are several bottlenecks in the fishery – the relative informality of relationships amongst players in the value chain, the independent livelihood‐driven harvest behaviours of fishers, and opportunistic sale of products. As a result, the fishery did not meet the demands of the domestic market. Our study concluded the gendered‐skewness in the fishery increases the vulnerability of the chain to declines in economic productivity because of its reliance on irregular suppliers, and gender‐based constraints. However, the low frequency and intensity of harvesting and use of low technological harvesting methods meant the fishery was not over‐exploited and likely sustainable. [ABSTRACT FROM AUTHOR]

Understanding 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 FROM AUTHOR]

Introduction: Vibrio alginolyticus is a Gram-negative, rod-shaped bacterium belonging to the family of Vibrionaceae, a common pathogen in aquaculture animals, However, studies on its impact on Scylla serrata (mud crabs) are limited. In this study, we isolated V. alginolyticus SWS from dead mud crab during a disease outbreak in a Hong Kong aquaculture farm, which caused up to 70% mortality during summer. Methods: Experimental infection and histopathology were used to investigate the pathogenicity of V. alginolyticus SWS in S. serrata and validate Koch's postulates. Comprehensive whole-genome analysis and phylogenetic analysis antimicrobial susceptibility testing, and biochemical characterization were also performed. Results: Our findings showed that V. alginolyticus SWS caused high mortality (75%) in S. serrata with infected individuals exhibiting inactivity, loss of appetite, decolored and darkened hepatopancreas, gills, and opaque muscle in the claw. Histopathological analysis revealed tissue damage and degeneration in the hepatopancreas, gills, and claw muscle suggesting direct and indirect impacts of V. alginolyticus SWS infection. Conclusions: This study provides a comprehensive characterization of V. alginolyticus SWS as an emerging pathogen in S. serrata aquaculture. Our findings underscore the importance of ongoing surveillance, early detection, and the development of targeted disease management strategies to mitigate the economic impact of vibriosis outbreaks in mud crab aquaculture. [ABSTRACT FROM AUTHOR]

The aim of the present study was to determine the extenders such as calcium-free saline, Ringer’s solution and phosphate buffer and to determine the effect of different concentrations of cryoprotectants with different duration of exposure for short-term storage of mud crab, Scylla tranquebarica sperm cells. A total of 30 mud crabs were used in the present study. In the present study, three treatments with three replicates were tested to determine the suitable extender. Three treatments (dimethyl sulfoxide, glycine and glycerol) were tested to determine the suitable cryoprotectants. Eight treatments (25, 20, 16, 4, 2, -4, -20, and -80°C) were assessed to determine the optimal cooling rate. The result showed the phosphate buffer solution produced the highest sperm viability (82.36 ± 5.84%) after 60 min compared the calcium-free saline and Ringer’s solution. Using 5% glycine as the optimal cryoprotectant, sperm viability at -80°C exhibited robust initial viability 95.17 ± 0.92% at 6 hours, 94.11 ± 0.64% at 12 hours, and 93.31 ± 0.51% at 24 hours. However, sperm viability gradually declined to 90.84 ± 2.05% by day 7, 82.82 ± 0.41% by day 14, and continued to decrease by day 21. In a nutshell, the phosphate buffer and 5% glycine proved to be the most effective extender and cryoprotectant in this study. [ABSTRACT FROM AUTHOR]

Copyright of Ege Journal of Fisheries & Aquatic Sciences (EgeJFAS) / Su Ürünleri Dergisi is the property of Ege Journal of Fisheries & Aquatic Sciences (EgeJFAS) / Su Urunleri Dergisi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mud crabs are common edible crustaceans, which are fished along the coasts of India. Scylla tranquebarica (Fabricius 1798), commonly called green crab is one of the most economically important portunid crab in India. The study was carried out to determine the sex ratio, maturation and spawning, gonadosomatic index, fecundity and egg diameter. Sex ratio of 1 female to 1.3 male gave good results. Size at first maturity was observed at 11 cm carapace width (CW) in males and 10 cm (CW) in females. The highest GSI values in males (6.17) and females (5.12) were observed in the month of October. The maximum number of eggs produced by the females was up to 5 million. The egg diameter was recorded in the range of 0.69 to 0.76 mm. The incubation period was 11-13 days. The hatching success average percentage was recorded as 80%. For the incubation and larval rearing of mud crab, Scylla tranquibarica, the optimum requirement of water temperature and salinity were recorded as 28°C and 30 ppt, respectively. [ABSTRACT FROM AUTHOR]

Marine Protected Areas limit fishing to protect a broad range of species and enhance biodiversity. Consequently, closures may not benefit species equally and species‐specific assessments are required to determine the impact of closures.Relative abundance and size of Giant Mud Crab (Scylla serrata) was compared across no‐take and fished zones in Port Stephens‐Great Lakes Marine Park, on the temperate east coast of Australia (32.45°S). In addition, passive acoustic telemetry was used to estimate daily space‐use areas.Similar abundances were observed between no‐take and fished zones; however certain no‐take sites had higher abundances than others. In addition, crabs were 9.9 mm larger in no‐take zones on average. Daily crab space‐use varied widely (~4 to 1000 m2), and generally increased with water temperature and conductivity.These patterns indicate that recruitment processes interact with marine park protection to shape crab abundances across estuaries. However no‐take zoning appears to primarily limit fishing mortality on legal size crabs (i.e., carapace length >85 mm) resulting in larger crabs within no‐take zones. This may mean no‐take zones enhance reproductive output of crab populations since larger individuals are likely to be more fecund. [ABSTRACT FROM AUTHOR]

IntroductionVibrio alginolyticus is a Gram-negative, rod-shaped bacterium belonging to the family of Vibrionaceae, a common pathogen in aquaculture animals, However, studies on its impact on Scylla serrata (mud crabs) are limited. In this study, we isolated V. alginolyticus SWS from dead mud crab during a disease outbreak in a Hong Kong aquaculture farm, which caused up to 70% mortality during summer.MethodsExperimental infection and histopathology were used to investigate the pathogenicity of V. alginolyticus SWS in S. serrata and validate Koch’s postulates. Comprehensive whole-genome analysis and phylogenetic analysis antimicrobial susceptibility testing, and biochemical characterization were also performed. ResultsOur findings showed that V. alginolyticus SWS caused high mortality (75%) in S. serrata with infected individuals exhibiting inactivity, loss of appetite, decolored and darkened hepatopancreas, gills, and opaque muscle in the claw. Histopathological analysis revealed tissue damage and degeneration in the hepatopancreas, gills, and claw muscle suggesting direct and indirect impacts of V. alginolyticus SWS infection.ConclusionsThis study provides a comprehensive characterization of V. alginolyticus SWS as an emerging pathogen in S. serrata aquaculture. Our findings underscore the importance of ongoing surveillance, early detection, and the development of targeted disease management strategies to mitigate the economic impact of vibriosis outbreaks in mud crab aquaculture.

The use of artificial feed in mud crab aquaculture continues to be developed considering that feed has an important role in growth, survival, and production costs. The largest production cost comes from feed, especially feed protein. The utilization of carbohydrates and lipids as feed protein savers in mud crab aquaculture has not been widely studied. This study aimed to analyze isoprotein feed with different carbohydrate and lipid ratios on molting, growth, and feed efficiency of mud crab, Scylla serrata. Mud crabs with a weight of 70± 4.7g/head and a carapace length of 5± 0.5cm were reared using crab boxes and placed in ponds for 60 days. Pterygoplichthys pardalis meal and maggot meal were used as feed protein sources. The treatments in this study were 35% iso-protein feeds with different carbohydrate and lipid ratios: treatments A (31 and 10%), B (33 and 9%), C (34 and 7%), and D (35 and 6%). This study used a completely randomized design consisting of four treatments and three replicates. The parameters observed were molting percentage (MP); growth (absolute weight growth "WG" and specific growth rate "SGR"); feed efficiency (protein retention "PR" & lipid retention "LR", feed conversion ratio "FCR", and survival "SR") in addition to the physicalchemical parameters of the research media. Data were analyzed using a completely randomized design, while water physico-chemistry was analyzed descriptively. The results showed that 35% iso-protein feed with different ratios of carbohydrates and lipids had no significant effect on molting, growth, and feed efficiency. However, there is a trend that the quality of crab meat with the carbohydrate and lipid ratio treatment of 31 and 10% is better than the other treatments. Similar research is still needed with more comprehensive studies and conducted in controlled media so that water quality does not experience extreme fluctuations. [ABSTRACT FROM AUTHOR]

Restoration projects are increasingly widespread and many promote habitat succession and the diversity and abundance of faunal communities. These positive effects on biodiversity and abundance may extend to enhancing the ecological functioning and resilience of previously degraded ecosystems, but this is rarely quantified. This study surveyed a 200‐ha restoring coastal wetland and three control wetlands in the Maroochy River, eastern Australia to compare the effects of wetland restoration on the consumption of carrion and the biodiversity, abundance, and functional diversity of functionally important fish and crustaceans. Carrion consumption by fish and crustaceans was measured every 6 months from spring 2017 until spring 2021 for nine events using a combination of baited cameras and scavenging assays. We found restoration improved rates of carrion consumption and the biodiversity, functional diversity, and abundance of scavenger species. Despite positive effects on the diversity of scavengers and carrion consumption, the abundance of two species, longfin eels (Anguilla reinhardtii) and mud crabs (Scylla serrata), was the most important predictors of carrion consumption rates. The spatial distribution of carrion consumption was concentrated in areas with high saltmarsh extent, moderate to high mangrove extent, and high salinity, which also resembled the distribution of both longfin eels and mud crabs. We show that restoration can promote the rates of key ecological functions but that increases to functions are likely to be characterized by low functional redundancy and greater complementarity. Therefore, maintaining or increasing the abundance of functionally important species should become a key objective in future restoration projects. [ABSTRACT FROM AUTHOR]

Achieving global targets for ecosystem restoration necessitates the development of effective restoration approaches. Current restoration approaches focus primarily on mitigating abiotic stresses or supplementing propagules to restore foundation species that support associated species by 'engineering' local habitats. Although keystone predators can strongly affect foundation species in natural ecosystems via trophic cascades and are often diminished in degraded ecosystems, they are traditionally neglected in efforts to restore foundation species.Here, we investigated how a keystone predator (Scylla serrata) might affect the restoration of a foundational plant (Scirpus mariqueter) in a degraded salt marsh. In a series of restoration experiments, we examined the effects of proximity to existing Scylla burrows, as well reintroducing Scylla, on the establishment of planted Scirpus in restoration areas. Furthermore, we tested if Scylla affected Scirpus via non‐consumptive effects in experiments that controlled Scylla's consumption of grazers.We found that planted Scirpus suffered less grazing and achieved higher density in areas closer to existing Scylla burrows where Scylla predation on grazers was stronger. Consistently, reintroduction of Scylla reduced grazing on Scirpus and increased its density by 360%. These positive effects of Scylla on Scirpus were driven by consumptive effects that reduced the abundance of grazers and by non‐consumptive effects that inhibited the herbivory by grazers.Synthesis and applications. These results demonstrate that incorporation of keystone predators, including both their consumptive and non‐consumptive effects, into restoration designs can greatly enhance the restoration of foundation species. Our study thus highlights the value of co‐restoring keystone predators and foundation species. Given that predators are depleted in many ecosystems, this co‐restoration approach may be broadly applicable. [ABSTRACT FROM AUTHOR]

Bone tissue engineering offers a novel therapy for repairing bone defects or fractures. However, it is becoming increasingly challenging because an ideal scaffold should possess a similar porous structure, high biocompatibility, and mechanical properties that match those of natural bone. To fabricate such a scaffold, biodegradable polymers are often preferred due to their degradability and tailored structure. This study involved the isolation of chitosan from crab shells (Scylla serrata) waste to use as a biomaterial in combination with hydroxyapatite (HAP) and collagen I (COL I) to mimic the extracellular matrix (ECM) composition of bone. After being cast and freeze-dried, it resulted in an interconnected porous scaffold with a porosity of 51.44% ± 2.28% and a pore diameter of 109.88 μm ± 49.84 μm. The swelling ratio of the crab scaffold was measured at 358.31% ± 25.23%, 363.04% ± 1.56%, and 370.11% ± 3.7% at 1, 3, and 6 h, respectively. Consequently, the scaffold exhibited a degradation ratio of 8.17% ± 2.59%, 21.62% ± 5.43%, 22.59% ± 14.23%, and 23.12% ± 6.28% over the course of 1 to 4 weeks. It demonstrated excellent biocompatibility with MG-63 osteosarcoma cells. Although the compression strength was lower than 2-12 MPa, the crab scaffold can still be applied effectively for non-load-bearing bone defects. Crab shell waste emerges as a promising source of chitosan for tissue engineering applications. [ABSTRACT FROM AUTHOR]

Effects of varied sediment and physico-chemical properties of water on allantoin content in tissues of Scylla serrata and its role in antioxidant homeostasis were investigated. Tissues of crabs were sampled from different coastal natural habitats of S. serrata of India during summer, winter, and rainy seasons and were analyzed to detect the variation in allantoin content and lipid peroxidation (LPx) and oxidative stress (OS) neutralizing antioxidant factors. High allantoin content in hepatopancreas over muscle tissue was observed in all seasons and sampling sites. The correlation coefficient values between allantoin and environmental factors, i.e., temperature, pH, salinity, organic carbon, Mg, and Ca, strongly support the stress-induced allantoin variation level in tissues. The level of allantoin had a negative correlation with levels of ROS, which was probably due to the upregulation of the activity of major antioxidant enzymes and assisting enzymes such as glutathione peroxidase (GPx), glutathione reductase (GR), and biotransforming enzyme glutathione -s- transferases (GST). A significant seasonal variation in the level of allantoin was correlated with the activity of including superoxide dismutase, catalase, GPx, GR, and GST, which was clearly noticed as a function of abiotic factors. Additionally, the level of allantoin did not correlate with small antioxidant molecules, such as ascorbic acid and reduced glutathione. Discriminant function analysis revealed that the level of allantoin and CAT and GR activities were the major contributing factors for the clear discrimination of groups. Therefore, allantoin can be considered as a significant factor for the seasonal modulation of OS physiology in mud crab Scylla serrata. [ABSTRACT FROM AUTHOR]

Chitosan is a marine polysaccharide commonly seen in the crustacean family, and the exoskeleton is covered by chitosan. In this study, shells of mud crabs were subjected to chitosan extraction which has been followed by demineralization, deproteination, and deacetylation. The chemical compositions of chitosans were characterized using Fourier transform infrared spectroscopy (FTIR). It exhibits antimicrobial activity against pathogens - E.coli, Staphylococcus, Klebsiella pneumonia, Bacillus cereus, and Salmonella typhi. It has therefore received attention as a potential food preservative. Transform Infrared Spectroscopy (FTIR) also spots out chemical bonds in a molecule by creating rather an infrared absorption spectrum. FTIR is an effective instrument for analysis and for also detecting the functional groups as well as characterizing covalent bonding information. FTIR spectroscopy finds out the functional molecules involved in the synthesis of nanoparticles and also, provides accuracy and reproducibility, which helps to detect small absorbance changes in the sample. The chemical compositions of chitosans were characterized further using FESEM.The FESEM pattern performs or indicates the silver nanoparticles to be embedded in a matrix of CS. The size of the particles is seen as with their uniformity. Not only this, but also the FESEM image of Ag nanoparticles shows somewhat the particles of spherical shape. Also, by Transmission Electron Microscopy (TEM) technique, the chemical compositions of chitosans were characterized. It exhibits that synthesized chitosan/silver nanocomposites have indeed a shape such as spherical with their uniformity as to their dispersion. Further, the chemical compositions of chitosans were characterized using Electron dispersive spectroscopy (EDS). The EDS histograms reveal rather successfully the percentage weight ratios of the elements found on the chitosan surface and the nanosilver concentrations in this study. In addition, by XRD analysis the chemical compositions of chitosans were characterized. It recognizes the multifarious crystalline phases present in the material so that the information touching the chemical compositions are revealed. In this study, mcf-7 cell line is chosen. Mcf-7 is a commonly used breast cancer cell line. For evaluation of anticancer study against mcf-7, the mcf-7 cell line is chosen for the study. In this study, anti-cancer study was very specially subjected to research and the chemical compositions of chitosans were characterized very seriously by FESEM, TEM, EDS, FTIR, and XRD for such anticancer study and therapy. [ABSTRACT FROM AUTHOR]

Copyright of Diversitas Journal is the property of Diversitas Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: Mud crab culture/fattening is a lucrative business with high profit margins because they have high economic and export value. Compared with shrimp culture, crab fattening has many advantages such as a short production cycle, high tolerance to poor water quality, rapid growth rates in captivity, etc. Currently, cheap commercial feed for crabs is unavailable, so raw feeds such as low‐value fishes have been used for rearing mud crabs. The current study was conducted to determine the growth performance of mud crab Scylla serrata that were fed with different processed wet feeds. Methods: Crabs weighing 250–300 g were stocked in individual cages, and the experiment was conducted with three different feed treatments including processed chicken intestine, processed shrimp head waste, oyster meat, and the control feed was processed small‐sized low‐value fish. Result: Of all the feeds, mud crabs that were fed with chicken intestine showed better performance, followed by oyster meat, shrimp head waste, and low‐value fish. Conclusion: The present study concludes that fattening mud crabs with chicken intestine as feed showed better growth and economic performance. Impact statementIn India, low‐value fishes have been generally used as a wet feed for mud crab culture. Using chicken intestine as an alternative wet feed enhances the growth performance and economic performance in the mud crab culture. [ABSTRACT FROM AUTHOR]

Mangrove crab (Scylla serrata) is one of the marine organisms that are of significant economic importance. The habitat is distributed in the coastal areas of Indonesia, within the extensive mangrove ecosystems, such as the estuary of Beladen in Dompak, Tanjungpinang. The Beladen estuary area features a flourishing mangrove ecosystem, which supports a diverse range of crab species, with a particular focus on the populations. Therefore, this study aimed to obtain several aspects of mangrove crab in the Beladen estuary, Tanjungpinang. Sampling by the census method was also carried out once every two weeks from May to June 2022. The results showed that the size composition of mangrove crab had a carapace width (CW) of 70-144 mm. The length-weight relationship reported that female and male exhibited a negative and positive allometric growth pattern (b < 3) and (b > 3), respectively. The proportion of male and female was 63% compared to 37% (sex ratio 1:0.59). The value of gonadal maturity index (GMI) in each size class ranged from 2,6512-7,1445 and 1,8751-6,7979 for male and female mangrove crab. Male and female gonadal maturity levels were predominantly categorized as II and III, indicating that crab with mature gonads was not encountered.

Decapod crustaceans have tooth-like white denticles that are present only on the pinching side of the claws. In the mud crab, Scylla serrata, a huge denticle exists on the movable finger of the dominant claw. This is mainly used to crush the shells of the crab's staple food. The local mechanical properties, hardness (HIT) and elastic modulus (Er), of the peak and valley areas of the largest denticle were examined via a nanoindentation test. The microstructure and elemental composition were characterized using a scanning electron microscope and energy-dispersive X-ray spectroscopy. The striation patterns originating from a twisted plywood structure parallel to the surface were visible over the entire denticle. Most of the largest denticle was occupied by a hard area without phosphorus, and there was a soft layer corresponding to the endocuticle with phosphorus in the innermost part. The HIT of the denticle valley was about 40% lower than that of the denticle peak, and the thickness of the soft endocuticle of the denticle valley was five times thicker than that of the denticle peak. The HIT–Er map showed that the abrasion resistance of the denticle surface was vastly superior and was in the top class among organisms. The claw denticles were designed with the necessary characteristics in the necessary places, as related to the ecology of the mud crab. [ABSTRACT FROM AUTHOR]

Anthropogenic alterations to river flow could have repercussions for flow-dependent species downstream but few studies account for these dynamic relationships or quantify impacts of altered river flow. Scylla serrata— a widely distributed portunid crab—was used as an example of a flow-dependent species to model impacts of altered flow on species abundance and catch. Crab population dynamics were modelled across a large semi-enclosed tropical sea in northern Australia. Environmental drivers, primarily river flow, but also temperature and the Southern Oscillation Index were linked to crab dynamics to explain variability in historical catches. Catch and abundance could then be predicted under altered flow scenarios. River flow significantly improved the ability to explain historical catches for some regions but not all, and the strength of this relationship varied across catchments. Altered flows had negligible effects for perennial rivers but for ephemeral and temporally variable rivers, predicted decreases in abundance and catch ranged from 36 to 46% on average. Our modelling approach showcases a way to dynamically and rigorously quantify impacts of altered river flow on a key species with potential to help inform natural resource management, including policy decisions on the timing, quantity, and method of water removed from rivers. [ABSTRACT FROM AUTHOR]

Aim: Spatially explicit protections of coastal habitats determined on the current distribution of species and ecosystems risk becoming obsolete in 100 years if the movement of species ranges outpaces management action. Hence, a critical step of conservation is predicting the efficacy of management actions in future. We aimed to determine how foundational, habitat‐building species will respond to climate change in Fiji. Location: The Republic of Fiji. Methods: We develop species distribution models (SDMs) using MaxEnt, General Additive Models and Boosted Regression Trees and publicly available data from the Global Biodiversity Information Facility to predict changes in distribution of suitable habitat for mangrove forests, coral habitat, seagrass meadows and critical fisheries invertebrates under several IPCC climate change scenarios in 2070 or 2100. We then overlay predicted distribution models onto existing Fijian protected area network to assess whether today's conservation measures will afford protection to tomorrow's distributions. Results: We found that mangrove suitability is projected to decrease along the Coral Coast and increase northward towards the Yasawa Islands due to precipitation changes. The response of seagrass meadows was predicted to be inconsistent and dependent on the climate scenario. Meanwhile, suitability for coral reefs was not predicted to decline significantly overall. The mangrove crab Scylla serrata, an important resource for fisherwomen in Fiji, is projected to increase in habitat suitability while economically important sea cucumber species will have highly variable responses to climate change. Main conclusions: Species distribution models are a critical tool for conservation managers, as linking spatial distribution data with future climate change scenarios can aid in the creation and resiliency of protected area programmes. New protected area designations should consider the future distribution of species to maximize benefits to those taxa. [ABSTRACT FROM AUTHOR]

Crab cell line, especially continuous crab cell line, can provide us a useful tool for studies on the virology, immunology, and molecular biology of crabs. However, no continuous crab cell line has been available due to the lacking of suitable medium and the occurrence of mitosis-arrest. In this study, long-term in vitro culture conditions for both two- (2D) and three-dimensions (3D) were successfully developed for the circulating hemocytes of swimming crab Portunus trituberculatus, designated as PTH cells. In 2D culture, a novel crab basic medium in osmolarity of 990–1 100 mOsm/kg was optimized for the first time, which is different from Leibovitz's L-15 medium in mainly the components of amino acids, containing double strengths of the contents of free amino acid mixture in the crab serum. Then an optimal crab growth medium was developed by supplementing 5% fetal bovine serum, 50-g/L yeast extract powder, 20-µg/L basic fibroblast growth factor and epidermal growth factor into the optimal crab basic medium, and found that it could support a long-term survival of PTH cells in a healthy monolayer up to 347 days and partially break through the mitosis-arrest of crab cells evidenced by the obvious increase of proliferating potential detected in the 10-d primarily cultured PTH cells. These 2D cultured PTH cells could be successfully sub-cultured for 11 times by physical flushing method and well cryopreserved in liquid nitrogen. In 3D culture, using the same crab growth medium, the PTH cell aggregates could be easily formed and healthily maintained on the surface of solidified Matrigel or in the ultra-low-attachment plate with a survival rate of 50%–60% on Day 103. This work largely improved the primary culture and subculture of crab cells and will facilitate the establishment of continuous crab cell line. [ABSTRACT FROM AUTHOR]

Peptide-based drugs have become the most promising drug therapy in the pharmaceutical industry. It accommodates a major part in treating diseases like neurodegenerative disorders, type 2 diabetes, and blood pressure. This study aims to isolate and characterize marine peptides from the crustacean crab species named Scylla serrata. The hemolymph was collected and subjected to thin-layer chromatography (TLC) and Fourier transform infrared spectroscopy for identifying amine groups. Furthermore, peptide groups in the sample were confirmed by nuclear magnetic resonance analysis. Ultra-performance liquid chromatography (UPLC) for the crude was performed to identify peak intensities. The sample was further purified with Sephadex G-25 to elute the small molecular peptides. Antioxidant activity (DPPH) for the crude sample showed 55% of activity at 100 µg/ml concentration, and the fractions showed significant activity. The eluted fractions from the column chromatography were then subjected to SDS PAGE to identify the molecular weight of the peptides in which the peptide bands ranged between 75 and 100 kDa. Furthermore, prospective compounds must be screened for potential drug candidates for Alzheimer's disease with an in silico approach. [ABSTRACT FROM AUTHOR]

Heavy metal (HM) contamination from mining activities poses a health risk to humans who consume mollusks and crustaceans from mine-affected environments. One such example is the Taft River, which receives drainage water and sediments from the Bagacay mines in Samar, Philippines. To assess the accumulation of HM in mollusks and crustaceans and the associated risks to the humans, a comprehensive analysis was conducted on representative specimens, which were gathered from different sections of the river. The concentrations of Cu (97.67 mg kg-1), Ni (29.30 mg kg-1), Pb (0.59 mg kg-1), and Sr (14.67 mg kg-1) in the flesh of "bebe" (Batissa violacea Lamarck) were significantly higher than those in "tangili" (Telescopium telescopium Linn.), "tuway" (Mercenaria mercenaria Linn.), and "sihi" (Nerita albicilla Linn.); whereas for crustaceans, the flesh of mud crabs (Scylla serrata) contained higher concentrations of As (17.67 mg kg-1), Cu (118.67 mg kg-1), Ni (25.79 mg kg-1), Rb (31.33 mg kg-1), Sr (60.67 mg kg-1), and Zn (331.00 mg kg-1) compared with giant freshwater prawns (Macrobrachium rosenbergii). The consumption of T. telescompium, N. albicilla, and B. violacea may result in an estimated daily intake (EDI) that is greater than the provisional tolerable daily intake (PTDI) for As [2.03-4.48 µg kg-1 body weight (BW) d-1], while all mollusks may have an EDI for Cr of between 124.59-136.23 48 µg kg-1 BW d-1. This may subsequently lead to a high target hazard quotient (THQ), high hazard index (HI), and high target cancer risk (TCR) for adults. With respect to crustaceans, the consumption of S. serrata exceeds the PTDI index for As. Both S. serrata and M. rosenbergii exceed the PTDI for Cr by 20-21 times, as well as the elevated health risk values of 22.36 and 28.57 48 µg kg-1 d-1 for M. rosenbergii and S. serrata, respectively. Overall, current results indicate that human consumption of the Taft River mollusks and crustaceans may inadvertently lead to an increased intake of As and Cr that could negatively impact human health. [ABSTRACT FROM AUTHOR]

Decapod crustaceans have tooth-like denticles on their claw fingers, which come into direct contact with predators and prey. Since the denticles are subject to more frequent and intense stress than other parts of the exoskeleton, they must be especially resistant to wear and abrasion. We clarified the mechanical resistance and tissue structure of the denticles arranged in a line on the fixed finger of the mud crab, which has huge claws. The denticles of the mud crab are small at the fingertip and become larger closer to the palm. The denticles have a twisted-plywood-pattern structure stacked parallel to the surface regardless of size, but the abrasion resistance strongly depends on the size of the denticles. Due to the dense tissue structure and calcification, the abrasion resistance increases as the denticle size increases, reaching its maximum at the denticle surface. The denticles of the mud crab have a tissue structure that prevents them from breaking when pinched. The high abrasion resistance of the large denticle surface is an essential feature for the frequent crushing of shellfish, which is the mud crab's staple food. The characteristics and tissue structure of the claw denticles on the mud crab may provide ideas for developing stronger, tougher materials. [ABSTRACT FROM AUTHOR]

Scylla serrata (Crustacea: Decapoda), which is widely spread on the intertidal mudflat of West Bengal, India's Sundarbans Biosphere Reserves, is a potential aqua crop and an economically significant edible species. One of the larger crab groups in the mangrove swamp of the Sundarbans is thought to be this one. The S. serrata's multifaceted immune response is directly tied to its diverse habitat and survival technique. It lives in dangerous surroundings and is constantly in danger of physiological stress brought on by various xenobiotics, such as arsenic. By producing a number of polyclonal antisera in rabbits (New Zealand White, albino), the study attempted to evaluate the surface antigen against crab hemocytes and murine lymphocytes. Control hemocytes and hemocytes treated to 1 ppm expressed very identical reactivity to antihemocyte sera for the agglutination reaction. The control results, however, shifted when exposed to 2 and 3 ppm of sodium arsenite, indicating arsenic-induced hemocyte surface modification. The agglutination reaction from the control sets of hemocytes that reacted with murine antilymphocyte sera gradually, shifted as the quantity of sodium arsenite in the medium of the treatment sets increased. The maximum equivalence zone of murine lymphocyte and hemocyte agglutination 98.6% and 99% respectively suggested a potential epitope sharing between two phylogenetically separate species. The situation may lead to a possible alteration of immune status and make opportunity for pathogenic foreign invaders within the mud crab body. Chronic arsenic exposure indicated a steady decline of edible and demandable S. serrata in the natural habitat of Sundarbans. [ABSTRACT FROM AUTHOR]

Infecting a wide range of hosts, members of Reovirales (formerly Reoviridae) consist of a genome with different numbers of segmented double stranded RNAs (dsRNA) encapsulated by a proteinaceous shell and carry out genome replication and transcription inside the virion. Several cryo-electron microscopy (cryo-EM) structures of reoviruses with 9, 10 or 11 segmented dsRNA genomes have revealed insights into genome arrangement and transcription. However, the structure and genome arrangement of 12-segmented Reovirales members remain poorly understood. Using cryo-EM, we determined the structure of mud crab reovirus (MCRV), a 12-segmented dsRNA virus that is a putative member of Reovirales in the non-turreted Sedoreoviridae family, to near-atomic resolutions with icosahedral symmetry (3.1 Å) and without imposing icosahedral symmetry (3.4 Å). These structures revealed the organization of the major capsid proteins in two layers: an outer T = 13 layer consisting of VP12 trimers and unique VP11 clamps, and an inner T = 1 layer consisting of VP3 dimers. Additionally, ten RNA dependent RNA polymerases (RdRp) were well resolved just below the VP3 layer but were offset from the 5-fold axes and arranged with D5 symmetry, which has not previously been seen in other members of Reovirales. The N-termini of VP3 were shown to adopt four unique conformations; two of which anchor the RdRps, while the other two conformations are likely involved in genome organization and capsid stability. Taken together, these structures provide a new level of understanding for capsid stabilization and genome organization of segmented dsRNA viruses. Author summary: Mud crab reovirus (MCRV), a putative member of the Sedoreoviridae family in Reovirales, infects an economically important crab, Scylla serrata, and has resulted in serious economic loss for the crab aquaculture. In this study, we report the structure of MCRV, which has allowed us to examine the detailed structural elements that might be responsible for capsid stability, as well as those involved in genome packaging and RdRp organization. The arrangement of viral polymerases inside the capsid differ from what has been seen in other viruses of the same order, as ten of the vertices are occupied by RdRp in a symmetrical organization not seen elsewhere. In addition, the VP11 protein is analogous to the "clamp" protein of turreted reovirads. [ABSTRACT FROM AUTHOR]

Background: Effective 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. Methods: We 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. Results: We 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. Conclusions: Our 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. [ABSTRACT FROM AUTHOR]

Herein, moribund mud crab (Scylla serrata) samples were collected from various farming systems, brooders from wild and hatchery quarantine section, located in Tamil Nadu, Andhra Pradesh, and Odisha. The infected crabs showed clinical signs of lethargic movement with the sleeping position in the culture ponds, tanks, and wild-caught. In the wet mount study, massive numbers of viral giant cells were observed in the infected crab hepatopancreas and connective tissue. Mud crab reovirus (MCRV) inclusion bodies were noticed in the connective tissue of hepatopancreas, gill lamellae, muscle and gonads in histopathology analysis. Also, viral particles proliferated into the cytoplasm of the cells, but they did not affect the host nuclei. The infected crab samples were confirmed in the PCR using specific primers (ReoF and ReoR) and rDNA sequence analysis showed 99% similarity with mud crab reovirus and Scylla serrata reovirus (OL466868 and OL466869). The ultrastructural study (TEM) revealed that MCRV viral particles ranged between 70 and 75 nm in diameter, icosahedral shape, and non-enveloped with two capsid layers located in the cytoplasm of the cells. The prevalence of mud crab reovirus infection was recorded between 80 and 100% in cultured farms within 25 days and 19–33% in the wild from the collected samples. In the pathogenicity study, intramuscular injection bioassay reached 100% mortality and a co-habitation assay was 70% mortality on 14 days of MCRV post-infection. Thus, our results suggest that MCRV is highly pathogenic to mud crab culture. [ABSTRACT FROM AUTHOR]

The oxidative stress (OS) condition and antioxidant level as a function of pH, few major elements, temperature, turbidity, organic carbon, sediment, and water salinity are vital to understanding the redox homeostasis of inhabiting animals. These parameters are also used to monitor environmental health. A spatiotemporal redox antioxidant system, followed by discriminant function analysis about the aforementioned abiotic factors, was investigated in the muscle, gill, and hepatopancreas of the mud crab, Scylla serrata, sampled from the Indian coastal belt along the Bay of Bengal (Tamil Nadu and Odisha) and the Arabian Sea (Gujarat) as a measure of environmental health assessment. Results revealed that the redox homeostasis of mud crabs significantly varied with seasonal fluctuations of abiotic factors and sediment chemistry. The level of superoxide dismutase and the non-protein-SH group were negatively correlated, whereas other antioxidant molecules with lipid peroxidation levels were positively correlated with abiotic factors. Only the activities of glutathione peroxidase and glutathione reductase were strongly correlated with all the abiotic factors. The hepatopancreas was found to be the most susceptible organ to OS. The lipid peroxidation level was 20–25 times higher in hepatopancreatic tissue than that in other tissues. The antioxidant level was elevated to 200% during the summer compared to the rainy season. Thus, the results of redox homeostasis in S. serrata may be useful for monitoring the ecotoxic effects of estuarine and marine environments and managing the inhabiting species.

Global climate change–induced ocean warming and acidification have complex reverberations on the physiological functioning of marine ectotherms. The Sundarbans estuarine system has been under threat for the past few decades due to natural and anthropogenic disturbances. In recent years, petroleum products' transportation and their usage have increased manifold, which causes accidental oil spills. The mud crab (Scylla serrata) is one of the most commercially exploited species in the Sundarbans. The key objective of this study was to delineate whether rearing under global environmental drivers (ocean acidification and warming) exacerbates the effect of a local driver (oil pollution) on the physiological energetics of mud crab (Scylla serrata) from the Sundarbans estuarine system. Animals were reared separately for 30 days under (a) the current climatic scenario (pH 8.1, 28°C) and (b) the predicted climate change scenario (pH 7.7, 34°C). After rearing for 30 days, 50% of the animals from each treatment were exposed to 5 mg L−1 of marine diesel oil for the next 24 h. Physiological energetics (ingestion rate, absorption rate, respiration rate, excretion rate, and scope for growth), thermal performance, thermal critical maxima (CTmax), acclimation response ratio (ARR), Arrhenius activation energy (AAE), temperature coefficient (Q10), warming tolerance (WT), and thermal safety margin (TSM) were evaluated. Ingestion and absorption rates were significantly reduced, whereas respiration and ammonia excretion rates significantly increased in stressful treatments, resulting in a significantly lower scope for growth. A profound impact on thermal performance was also noticed, leading to a downward shift in CTmax value for stress-acclimated treatment. The present results clearly highlighted the detrimental combined effect of global climatic stressors and pollution on the physiological energetics of crabs that might potentially reduce their population and affect coastal aquaculture in forthcoming years. [ABSTRACT FROM AUTHOR]

The mud crab, Scylla serrata, has huge claws in comparison with its body size. The color of the claw top's finger surface changes from white to deep-mottled blue, and this discoloration was strongly associated with the change in hardness inside the finger cross section. With special attention to the discoloration points, the tissue structure of the exoskeleton was investigated via scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction (XRD), and the mechanical properties were examined using Vickers hardness and nanoindentation tests. The exocuticle in the deep blue surface exoskeleton was as thin as that in other crustaceans, and the exoskeleton was occupied by the endocuticle with a twisted plywood structure. On the other hand, in the white surface exoskeleton, the thickness of the hard and dense exocuticle accounted for 52–59% of the exoskeleton thickness. This percentage increased at the claw tip. The hardness of the exocuticle was 2.5 times that of the endocuticle, and the microstructures and mechanical properties gradually varied at the boundary between the exo- and endocuticle. The mechanical properties were almost constant in the exocuticle, but calcium (Ca) concentrations decreased from the outer surface toward the boundary in that region and magnesium (Mg) concentrations increased. The change in the unit cell volume obtained via XRD suggested that some of the Ca atoms in the calcite crystal structure in that region were replaced with Mg atoms. Changes in crustacean coloration may help us to understand the tissue structure and mechanical properties within the exoskeleton. [ABSTRACT FROM AUTHOR]

Swimming crabs of the genus Portunus are revised based on analysis of three genetic markers (COI , 16S and H3) and a morphological comparison. The analyses reveal the polyphyletic composition of Monomia , Portunus and Xiphonectes and the paraphyly of Achelous. Portunus , in our revised composition, is restricted to 13, Monomia to ten and Xiphonectes to 14 species. Other species are transferred to Achelous (28) and Cycloachelous (nine) or to newly established genera. Four new genera are separated from Xiphonectes and one new genus from Monomia. The systematic composition of the portunid subfamily Portuninae now comprises 11 genera: Arenaeus , Allomonomia gen. nov. , Cavoportunus , Callinectes , Cycloachelous , Eodemus gen. nov. , Incultus gen. nov. , Monomia , Portunus , Trionectes gen. nov. and Xiphonectes. The genus Lupella is synonymized with Achelous (Achelouinae). Xiphonectes pulchricristatus and Xiphonectes spinipes are placed in Alionectes gen. nov. , Portunus ponticus is transferred to Lupocycloporus (both Lupocyclinae), and Monomia euglypha is now placed in Cycloachelous (Portuninae). Portunus mokyevskyi is considered a junior synonym of Scylla tranquebarica (Necronectinae). Xiphonectes leptocheles is confirmed as a valid species. Cycloachelous granulatus unispinosus is also considered a valid species and is to be treated as Cycloachelous unispinosus. [ABSTRACT FROM AUTHOR]

Connectivity is an essential driver for aquatic species distribution, genetic variability and stock structure. The giant mud crab (Scylla serrata) is a coastal portunid commonly associated with estuaries and mangrove systems. This species has been observed to undertake a seaward spawning migration, as the larval development is known to be more successful under the stable environmental conditions typically found in marine waters. The larvae return to the coastal areas through advection, where they are recruited and enter the estuaries after metamorphosing into the first instar. Here, we used numerical modelling to test hypotheses regarding probabilities of larval settlement of the giant mud crab and the effect of the distance offshore from which females release the eggs. Our scenarios considered the biological characteristics of larvae and oceanographic conditions for six locations for mud crabs along a complex coastline - the Queensland east coast, Australia. The models suggest that all locations tend to self-supply, and to exchange mud crab larvae with other regions, but in different magnitudes. The spawning distance offshore considerably affects larval distribution and settlement. The main drivers for larval advection in areas within the continental shelf are wind patterns and coastal currents, while offshore along the Australian continental slope, the main drivers are ocean currents. Self-recruitment is predominant, although we also observed a significant degree of connectivity between each location and the surrounding coastline. Short spawning migrations benefit self-recruitment in all scenarios, but long offshore migrations favour connectivity among different locations. This source/sink balance seems to depend on the local oceanographic features. Nevertheless, offshore spawning by the giant mud crab has the potential to provide for successful recruitment in a variety of environmental contexts. This study provides novel predictions of the probabilities of larval settlement for mud crab populations considering ocean advection that can be applied to different contexts. [Display omitted] • Numerical simulation was used to infer probabilities of mud crab larvae settlement. • The study considered six mud crab locations on Queensland's east coast. • Short migrations benefit self-recruitment, while long migrations favour connectivity. • To some degree, all locations act as providers and receivers of mud crab larvae. [ABSTRACT FROM AUTHOR]

A 336-base pair (bp) sized mRNA sequence encoding 111 amino acid size crustin isoform (MC-crustin) was obtained from the gill sample of the green mud crab, Scylla serrata. MC-crustin possessed an N-terminal signal peptide region comprising of 21 amino acid residues, followed by a 90 amino acid mature peptide region having a molecular weight of 10.164 kDa, charge + 4.25 and theoretical pI of 8.27. Sequence alignment and phylogenetic tree analyses revealed the peptide to be a Type I crustin, with four conserved cysteine residues forming the cysteine rich region, followed by WAP domain. MC-crustin was cationic with cysteine/proline rich structure and was predicted with antimicrobial, anti-inflammatory, anti-angiogenic and anti-hypertensive property making it a potential molecule for possible therapeutic applications. [ABSTRACT FROM AUTHOR]

Three isoenergetic diets differing in their fishmeal/soy protein concentrate (SPC) ratio were assessed on the tissue growth and energy budget of juvenile crabs Scylla serrata in postmolt stages (PMolt) and in intermolt stages (IMolt). The average growth rates on a dry matter basis were 2.064 ± 0.324% and 0.492 ± 0.08% initial BW.day−1 during PMolt and IMolt stages, respectively. The efficiencies of the feed conversion (FCE, %), protein retention (PRE, %) and energy retention (ERE, %) were similar for the three experimental diets. However, FCE, PRE and ERE in PMolt stages were four to five times higher than in IMolt stages. The feed intake, energy and protein required for growth in PMolt stages were obviously higher than in IMolt stages. The energy budgets (% total energy intake) were marginally affected by diet but were significantly affected by the molt stage. The maintenance energy was lower in PMolt stages (49.84 ± 4.9%) than in IMolt stages (83.33 ± 2.45%). The excess in maintenance energy in IMolt stages represents the portion set aside for the next molt: shell energy content (4.97 ± 0.31%) and energy for ecdysis (±28%). Conversely, recovery energy was significantly higher in PMolt stages (34.39 ± 0.99%) than in IMolt stages (8.33 ± 1.7%). In conclusion, SPC sustained good tissue growth and good feed utilization and can be used as a main source of dietary protein for crab juveniles in captivity. [ABSTRACT FROM AUTHOR]

Despite the progress in the production of artificial diets for marine larvae, feeding during the early life stages of most aquaculture species still relies on live feeds such as rotifers. Advanced rotifer culture techniques are also available, however, in the Philippines, majority use batch cultures with fresh microalgae. These microalgae are prone to collapse resulting to inadequate supply of food for the rotifers that are fed to the larvae. Mangrove crab is one of the economically important aquaculture species in the country where mass seed production requires sufficient and steady supply of rotifers. Thus, here we examined the possibility of substituting fresh culture of green microalgae Tetraselmis tetrathele (FA) with flocculated T. tetrathele paste (FP) and commercially available Tetraselmis sp. (CP) as feed for rotifers (Brachionus rotundiformis) in the seed production of mangrove crab. Rearing of larvae was done until crab instar 1 (DOC 24) where growth and survival were taken to evaluate the viability of rotifers-fed microalgal paste. It was observed that the growth index (FA–6.93 ± 0.07; FP–6.91 ± 0.07; CP–6.96 ± 0.05) was similar for all treatments (P > 0.05) at termination. Comparable survival rates were noted for FA and FP at 1.08 ± 0.59% and 3.21 ± 2.09%, respectively (P > 0.05) while a significantly higher survival (P < 0.05) was recorded for CP at 7.73 ± 1.90%. These findings suggest that the algal paste tested are potential alternatives to fresh microalgae and this technique could benefit hatchery operators who lack the capital for setting up the facility and technical skills to maintain microalgae production. [ABSTRACT FROM AUTHOR]

The claws of the mud crab, Scylla serrata, are huge in comparison with its body size. Many bulges ranging from 5 to 23 μm in height and 90 to 146 µm in diameter were observed on the mottled, deep-blue exoskeleton surface of the mud crab's claw. These cuticle bulges were closely related to irregularly present exocuticles on the surface layer of the exoskeleton's cross section. The bulges exist between the exocuticles, and at the apex of these bulges was a tube that bundled many pore canals that penetrated the exoskeleton. This tube was thick (62–66 µm) near the inner side and narrowed (12–22 µm) toward the outer surface. On the other hand, the exocuticles had a heterogeneous tissue structure in a coarse region extending normally to the surface, with a diameter of 3 to 7 µm, and a dense region between them. Calcium concentrations were high in the dense region, and phosphorus and magnesium concentrations were high in the coarse region. As a result, the mechanical properties (hardness: H and modulus: Er) were distributed inside the exocuticle, and the mapping of H and Er using a nanoindentation test clarified the heterogeneity. [ABSTRACT FROM AUTHOR]

The effects of feeding rotifers and Artemia enriched with different types of enrichment in the first feeding and later stages of Scylla tranquebarica larvae were investigated. Two different experiments were conducted each with five enrichment treatments including live and digestible Nannochloropsis sp. and Tetraselmis sp. or commercial product. In Experiment I, the zoea 1 (Z1) larvae were fed with enriched or unenriched rotifers as their first feed until they moulted into the zoea 2 (Z2) stage, while in Experiment II, the zoea 3 (Z3) larvae were fed with enriched or unenriched Artemia until they metamorphosed into megalopa stage. In Experiment I, Z1 fed enriched rotifers showed higher survival, larval stage index (LSI) and carapace length than those in unenriched treatment. However, the highest survival was recorded in larvae fed Nannochloropsis sp. treatment. In Experiment II, Z3 fed Artemia enriched with digestible Tetraselmis sp. exhibited the highest survival and LSI, lowest chela‐carapace length ratio and abnormal moulting frequencies. In comparison to live microalgae, digestible treatment resulted in a smaller chela‐carapace length ratio with lower abnormal moulting. In conclusion, enrichments tested in this study can be used to enrich rotifers for the first feeding of Z1, while later stage (Z3 onwards) fed Artemia enriched with digestible Tetraselmis sp. improved survival and decreased the abnormal moulting frequencies of Z5 to megalopa stage. [ABSTRACT FROM AUTHOR]

Segara Anakan mangrove waters is a lagoon surrounded by mangrove forests and muddy land. Mangrove forests have an ecological function, such as spawning ground, nursery ground, and feeding ground for various biota. Mud crab is one of the fishery commodities which is important in Indonesia. Segara Anakan mangrove waters is one of the fishing villages which catch mud crabs because of the high demand. The high demand for mud crabs needs to be balanced with the right management strategy so that the population will not extinction. This study aims to determine the ecology of mud crab, Scylla serrata Forskål, 1775 and its fishery potential and explain the habitat population in the Segara Anakan mangrove forest. Many previous studies were conducted by previous researchers. Environmental parameters, i.e. temperature, salinity, oxygen, light penetration, and nature of the bottom were also studied. Crabs were caught by a traditional crab catch fishery called “Wadong” (fish pot). Around 6.487 crabs were caught by “wadong”. The catch consisted of 2.920 male crabs (45,02%) and 3.567 female crabs (54,98%). The dominant size groups for males and females in terms of their carapace length (CL) were 35,00–40,00 mm and 43,00–106,00 mm, respectively. Females mature at a smaller size, i.e., at 42,70 mm CL. Breeding takes places from June–July. CL weight relationship showed that males were heavier than females. The regression equations for both sexes are as follows: WF = 10-3 5,871 L2.4443 (r = 0,999) and WM = 10-4 4,043 L3.1035 (r = 0,999). [ABSTRACT FROM AUTHOR]

Mangrove crab Scylla serrata is associated with mangroves throughout the Indian and Pacific oceans. This species is crucial to aquaculture and fishing. As wild stocks decline and demand rises, mangrove crab aquaculture has become increasingly popular. However, feed development research and its quality are still meager in the industry. This study examined the interactive effects of different levels of crab shellmeal (CSM) to fishmeal (FM) replacement on proximate composition, feed utilization, carcass composition, growth, and survival performance of mangrove crab S. serrata. Four formulated diets were prepared, and one for chopped trash fish (TF) supplement: 30% FM and 0% CSM (Diet 1) as a negative control, 20% FM and 10% CSM (Diet 2), 10% FM and 20% CSM (Diet 3), 0% FM and 30% CSM (Diet 4), and TF as a positive control (Diet 5). Experiments were conducted in each group for 30 days with ten replicates. Results revealed that formulated diets using different levels of CSM and FM did not significantly affect mangrove crabs' growth and survival rates as well as feed utilization. However, the proximate composition of Diet 4 was significantly higher among other experimental diets. Moreover, the crab's whole body composition (ash, moisture, carbohydrates, crude protein, crude fat, and calories) with different levels of CSM and FM was significantly improved. Hence, it is possible to enhance the carcass composition and proximate composition by supplementing CSM; however, it has no effect on feed utilization, as well as the growth and survival rates of mangrove crab S. serrata. [ABSTRACT FROM AUTHOR]

Aquaculture development and expansion can destroy and reduce tropical mangrove systems, while discharging sewage into the ocean. This study introduced a new mangrove system into an aquaculture pond to establish a mangrove–aquaculture coupling system. This study aims to reduce pond water eutrophication and decrease nutrient discharge into the ocean without affecting aquaculture. Results show that mangrove planting does not affect Scylla serrata growth (mud crabs), but does stabilize pond environments. While mangrove‐planting inhibits nitrogen and reactive P (PO43−) accumulation in ponds, it is a poor inhibitor of total phosphorus accumulation. The average nitrite (NO2−), reactive P (PO43−), and total nitrogen (TN) contents decreased by 80.46, 35.47, and 31.01%, respectively. This mangrove–aquaculture coupling system provides a method to balance economic development needs with the ecological needs of mangrove wetlands. This study offers suggestions for establishing this system and its associated waste aquaculture pond transformation. [ABSTRACT FROM AUTHOR]

Larval dispersal and connectivity have important implications for fisheries management, especially for species with life cycles influenced by ocean boundary currents. Giant Mud Crab (Scylla serrata) and Blue Swimmer Crab (Portunus armatus) are two estuarine portunid crabs (Family: Portunidae) that support significant commercial and recreational harvest in eastern Australia. Giant Mud Crab migrate to coastal waters to spawn, and while Blue Swimmer Crab spawn primarily within estuaries they occasionally migrate to coastal waters to spawn, followed by larval dispersal in the East Australian Current (EAC). Here, we coupled a high‐resolution oceanographic model with a Lagrangian particle tracking framework to simulate larval dispersal and determine the extent of population connectivity in this region. Our simulations indicate broad‐scale connectivity (~40–400 km), characterised by high inter‐estuary connectivity. Overall, our results suggest a north‐to‐south source‐sink structure for both species, with contributions of particles from the north ranging from 51% to 99%. Recruitment to a given estuary is dependent on the proximity of mesoscale oceanographic features of the EAC. Most notably, the EAC separation acts as a barrier to recruitment between spawning and settlement to the north/south of this region. This significantly limits interjurisdictional connectivity for these species, especially Blue Swimmer Crab, likely due to a shorter pelagic larval duration than Giant Mud Crab. Our results provide evidence to inform the assessment and management of these species. [ABSTRACT FROM AUTHOR]

Spawning is a key life history event for aquatic species that can be triggered by environmental signals. For estuarine-dependent species, the timing of such triggers can be important for determining future patterns in recruitment. Here, we used acoustic telemetry to identify the potential drivers of spawning migration in female Giant Mud Crabs (Scylla serrata). Eighty-nine mature female crabs were tagged in two subtropical south-east Australian estuaries, the Clarence River (~ 29.4°S) and Kalang River (~ 30.5°S), during the summer spawning season (November–June) over two years (2018/19 and 2020/21), and their movements were monitored for up to 68 d, alongside high-resolution environmental data. Crabs were considered to have 'successfully' migrated if they were detected at the mouth of the estuary, a behaviour exhibited by 52% of tagged crabs. The highest probability of migration was associated with relatively low temperatures (< 22 °C) and when conductivity rapidly declined (< -10 mS cm−1 d−1) following heavy rainfall. Furthermore, migration coincided with larger tides associated with the new and full moon, and following heavy rainfall, which may aid rapid downstream migration. Oceanic detections of 14 crabs (30% of 'successful' migrators) showed that once crabs left estuaries they migrated north. These patterns show that variability in environmental triggers for spawning migrations may contribute to interannual variation in spawning patterns, which may in turn impact fisheries productivity in this region. [ABSTRACT FROM AUTHOR]