Wild Mud Crab Research Articles (Page 1)

Comparative analysis of the microbiota in wild mud crab (Scylla serrata) intestine, sediment, and water in Koggala Lagoon, Sri Lanka

Changes of nutrient composition in the ovaries and hepatopancreas of mud crab Scylla paramamosain broodstock and their offspring performance at different salinities

This study was conducted to investigate the reproductive cycle and size at maturity of wild mud crab, Scylla tranquebarica, in the mangrove forest of Marudu Bay. The sampling was conducted for 12-month consecutively with the assistance of local fishermen. Each sampling was carried out for 2 days, and baited crab traps were deployed in the river. During the sampling period, a total of 1459 crab specimens were caught. The different maturation stages of crab can be found throughout the year. The percentage of mature female crabs (Stage III to V) was relatively higher in February (38.5%) and May (50.5%), and lower in March (17.6%) and June (17.4%). A similar trend was observed in the male crab. Recruitment of crabs into the mangrove forest was observed after the breeding season. It was observed through histological observations that when 50% of the crabs were sexually mature, the size at maturity was in the range of 94.0 to 96.1 mm and 97.0 to 99.5 mm carapace width for female and male, respectively. This study suggests that S. tranquebarica breeds throughout the year and shows two peak breeding seasons and recruitment in Marudu Bay. This information can be used as baseline for mud crab fisheries management in Sabah.

The selected study area in Fisheries Management Area (FMA) 713 in Kartanegara District, East Kalimantan Province, Indonesia has extensive mangrove forests with suitable habitat for mud crabs (Scylla sp.), a valuable fisheries resource. Concerns have been raised regarding reported declines in the abundance of mud crabs and in the condition of their mangrove habitat. To evaluate the management status of the mud crab fishery in this area, an assessment was carried out using the Indonesian Ecosystem Approach to Fisheries Management (EAFM) methodology. The 25 indicators assessed represent 6 domains: Fisheries Resources, Habitat and Ecosystems, Fishing Technology, Social, Economic, and Institutional. The flag model technique was applied using multi-criteria analysis through an expansion of the composite index. The results indicate that the overall management status of mud crab fisheries in Kutai Kartanegara District was in the Moderate class (on a scale of Poor, Insufficient, Moderate, Good, Excellent). Indicators in the Habitat and Ecosystems, Fishing Technology, and Institutional Domains highlighted areas of concern where improvements are needed. The Fisheries Resources Domain aggregate status (moderate) indicated that wild mud crab stocks were still reasonably abundant and reliable, supporting the moderate status in the Social and Economic Domains, which relate to the welfare of fishing communities. The Institutional Domain status was in the poor category. Good governance measures to improve the Institutional Domain indicators have the potential to strengthen the other domains, in particular the Habitat and Ecosystem Domain and the Fishing Technology Domain, and to improve the overall EAFM status of the mud crab fishery in the future.

BackgroundMud crab, Scylla paramamosain, a euryhaline crustacean species, mainly inhabits the Indo-Western Pacific region. Wild mud crab spawn in high-salt condition and the salinity reduced with the growth of the hatching larvae. When the larvae grow up to megalopa, they migrate back to estuaries and coasts in virtue of the flood tide, settle and recruit adult habitats and metamorphose into the crablet stage. Adult crab can even survive in a wide salinity of 0–35 ppt. To investigate the mRNA profile after salinity stress, S. paramamosain megalopa were exposed to different salinity seawater (low, 14 ppt; control, 25 ppt; high, 39 ppt).ResultsFirstly, from the expression profiles of Na+/K+/2Cl- cotransporter, chloride channel protein 2, and ABC transporter, it turned out that the 24 h might be the most influenced duration in the short-term stress. We collected megalopa under different salinity for 24 h and then submitted to mRNA profiling. Totally, 57.87 Gb Clean Data were obtained. The comparative genomic analysis detected 342 differentially expressed genes (DEGs). The most significantly DEGs include gamma-butyrobetaine dioxygenase-like, facilitated trehalose transporter Tret1, sodium/potassium-transporting ATPase subunit alpha, rhodanese 1-like protein, etc. And the significantly enriched pathways were lysine degradation, choline metabolism in cancer, phospholipase D signaling pathway, Fc gamma R-mediated phagocytosis, and sphingolipid signaling pathway. The results indicate that in the short-term salinity stress, the megalopa might regulate some mechanism such as metabolism, immunity responses, osmoregulation to adapt to the alteration of the environment.ConclusionsThis study represents the first genome-wide transcriptome analysis of S. paramamosain megalopa for studying its stress adaption mechanisms under different salinity. The results reveal numbers of genes modified by salinity stress and some important pathways, which will provide valuable resources for discovering the molecular basis of salinity stress adaptation of S. paramamosain larvae and further boost the understanding of the potential molecular mechanisms of salinity stress adaptation for crustacean species.

First detection of white spot syndrome virus (WSSV) in wild mud crab Scylla spp. (de Haan, 1883) from Setiu Wetlands, Malaysia

Nonvolatile taste active compounds, including free amino acids (FAAs), 5′-nucleotides, betaine, soluble sugars, trimethylamine oxide and organic acids of wild and cultured mud crab Scylla paramamosain were examined. The main taste in mud crab (MC) is derived from the FAAs, 5′-nucleotides, betaine, and organic acids, based on the fact that these compounds have a taste activity value (TAV) > 1. Wild MCs had a higher content of total FAAs, 5′-nucleotides, betaine, and organic acids in meat compared with cultured animals. However, no differences in the taste active compound levels were observed in the gonads of wild and cultured MCs, with betaine being the exception (wild crab > cultured crab). The total concentrations of FAAs in MC ranged from 12.71 to 36.94 mg/g. Monosodium glutamate (MSG)-like FAAs were primarily contributed by glutamic acid, and ranged from 0.71 to 0.93 mg/g. The concentrations of 5′-nucleotides were 1.10–2.24 mg/g, in which 5′-inosine monophosphate (IMP) and 5′-adenosine monophosphate (AMP) were the predominant TAVs (TAV > 1). The total concentrations of organic acids in MC were 2.41–11.10 mg/g, in which lactic and succinic acid in meat, and citric acid and succinic acid in female gonads were the main organic acids. The gonads were observed to have higher concentrations of 5′-nucleotides and organic acids compared with crab meat, with the equivalent umami concentration in gonads being higher than that in crab meat. In conclusion, wild MCs contained more active-taste nonvolatile flavor components relative to those detected in cultured MCs.

Mud crab (MC) aquaculture is rapidly developing fast worldwide, and there is a high consumer demand for Scylla paramamosain. Demand for MCs is especially high in China, where such crabs, especially the gravid females, are regarded a delicacy. In Hainan Island, pond-rearing wild MC juveniles in the presence of local trash fish and shrimps in brackish water has been shown to be successful. The nutritional value of cultured MC, however, has not been evaluated. In this paper, the biochemical composition of pond-cultured and wild gravid female MCs was studied. The cultured MCs had a higher ratio of total edible yield than the wild ones. The contents of crude protein and crude lipid in the cultured MCs were significantly lower than in the wild MCs (P < 0.05). Furthermore, the total amino acid (TAA) and essential amino acid (EAA) contents of gonads in the wild MCs were both significantly higher than those in the cultured MCs (P < 0.05). The TAAs and EAAs of claw and body muscles in cultured MCs, however, were significantly higher (P < 0.05). There were no significant differences in the contents of polyunsaturated fatty acids (PUFAs), n-3 fatty acids, and n-6 fatty acids in the gonad of bothMCgroups, whereas the contents of total saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) were significantly different between the wild and the cultured MCs (P < 0.05). Furthermore, there were no significant differences in the contents of SFAs, MUFAs, and PUFAs in both claw and body muscle between the wild and cultured MCs.

Investigation of Parasites and Ecto-Symbiont in Wild Mud Crab, Genus Scylla from Terengganu Coastal Water, Malaysia: Prevalence and Mean Intensity

Most Asian country have been success for the culturing of the mud crab i.e. Thailand, Vietnam and Philippines but no action were taken to solve the barnacle infestation problem of mud crab. Previous study did not mention about significant of the attachment of pedunculate barnacle to the mud crab. But somehow, this pedunculate barnacle may be able to give effect to the mud crab respiratory system especially for adult mud crab. This preliminary study are to observe the effect of the pedunculate barnacle attachment to their host using histopathological and Scanning Electron Microscopy (Tabletop SEM 1000, Hitachi) observation. Histological sectioning of gill wild mud crab with the Hematoxylene and Eosin staining (H&E Stain) were done to study about their effect. The results show the attachment of the pedunculate barnacle is temporary and will be left the host-gill during molting period.

Morphological Distribution of Pedunculate Barnacle Octolasmis cor (Aurivillius, 1892) found on Gill of Wild Mud Crab (Genus: Scylla) from Terengganu Coastal Waters, Malaysia

Morphological Description of Pedunculate Barnacle Octolasmis angulata (Aurivillius, 1894) on Wild Mud Crab Genus Scylla from Setiu Wetland, Terengganu Coastal Water, Malaysia

The significant decrease in wild mud crab population highlights the need to manage the resources and domesticate crabs. This paper presents the initial results of the domestication of mud crab Scylla serrata aimed at producing good-quality captive broodstock. The analysis of the genetic structure of the base population was done as a prerequisite for domestication. Adult S. serrata from the northern to southern parts of the Philippines (Cagayan, Camarines, Samar, and Surigao) were obtained for genetic diversity analysis and domestication. Analysis of molecular variance showed that differences in the genetic variability between the four populations were not significant. Moreover, no significant deviation from Hardy–Weinberg Equilibrium was observed in each sample population and even in pooled populations. Body weight was positively correlated with the carapace width. Second spawning occurred 41–46 days after the first spawning and 34 days from second to third spawning. However, there was a decrease in the number of zoea in repeat spawnings. Twenty-four first-generation (F1) families were produced from the four sites. The duration from spawning of the base population (P0) to attainment of broodstock size F1 was 10–14 months. Four second-generation (F2) families were produced after 11–12 months. Up to the F2, crabs tested negative for six viruses: white spot syndrome virus, infectious hypodermal and hematopoietic necrosis virus, gill-associated virus, yellow head virus, Taura syndrome virus, and infectious myonecrosis virus. The reproductive performance of P0 was comparable to the succeeding generations. Several families were obtained from one population in a year. However, due to the cannibalistic behavior of crabs, more space is required for the nursery and grow-out phase. The domestication of S. serrata is the first study done on any mud crab species in the Indo-west Pacific region. The initial results would serve as guide to understand and eliminate the barriers to mud crab domestication. The breeding technology developed from this study will support the production of good-quality seedstock for farming.

A study was carried out to investigate the presence of bacteria flora in wild mud crab (Scylla serrata) from Setiu Wetland as well as their antibiotic resistances. A total of 91 bacterial isolates consisting of 12 bacterial species were successfully isolated from mud crab. Oxolinic acid was found to be effective against all the bacterial isolates whilst the highest percentage of antibiotic resistance was shown by lincomycin (94.5%) followed by ampicillin (90.1%), amoxicillin (86.8%) and oleandomycin (78.0%). The study is very useful to evaluate the safety of mud crab for human consumption based on wild mud crab-associated bacteria as well as their antibiotic resistances.

Accumulation of Lipofuscin and Preliminary Estimation of Age-Structure in Wild Mud Crab (Scylla paramamosain) Population in Tropical Mangrove Swamps, Thailand