The Effect of Different Salinity on Moulting of Mud Crab (Scylla serrata) in Controlled Media

Market demand for mud crab (Scylla serrata) is increasing so that its catch in nature is high in the long term. The growth of mud crabs (Scylla serrata) occurs through molting (molting) mechanisms. Softshell crab has a higher economic value than hard shell crab. The purpose of this study was to assess the molting rate of mud crab (Scylla serrata) with different salinity treatments in controlled containers. The study used a completely randomized design (CRD) with three treatments of 20 ppt, 25 ppt, and 30 ppt salinity with three replications. The crabs used are mud crabs (Scylla serrata) measuring 80-175 grams with the carapace still hard. The test parameters include the weight gain and absolute length of the individual, daily growth rate, molting percentage, and survival and mortality rates. Besides, the chemical-chemical parameters of the culture media water and the effectiveness of using controlled containers were also observed. The research data were analyzed descriptively quantitatively. The difference in treatment and the use of controlled containers had a significant effect on the 95% significance level (α = 0.05) on all parameters of the response to treatment. Absolute individual weight values 40.6 – 47.41 grams, absolute individual length 2.6 – 3.2 cm, molting percentage 75 – 100%, daily growth rate 1.3 – 1.6 grams, 75 – 100% survival and mortality of mud crab (Scylla serrata) 25-16.7%. Optimal salinity level at 20 ppt. Water quality parameters during the study were still feasible for mangrove crab (Scylla serrata) cultivation. Controlled containers using a water rotation system are quite effective for the cultivation of mud crab (Scylla serrata).

Feeding with a balanced formulation of nutrition, can help the process of growth and moulting of mub crab,Scylla serrata. In general, the Soca crab aquaculture utilize feed that is still competitive with humans thereby increasing the cost operasional, while in the intensive aquaculture require the availability of feed in a number of good quality, inexpensive, sustainable and high production value. One of an alternative food for the growth of mud crab is temberungun snail (Telescopium-telescopium), which is a waste of traditional farming in ponds. This study aimed to compare the effect of temberungun snail as a feed with other feeds that high economic value for the growth and moulting of mud crab. The research was carried on January to May in traditional ponds in the small island of Tarakan. Four feed treatments were applied: A = trash fish, B = temberungun snails (Telescopium-telescopium), C = crustaceans (Penaeid sp), D = squid (Loligo sp). The results of the studi showed that the use of non-economical feed of temberungun snail was not significantly different with the other natural feed that high economic value to growth and moulting of mud crab. Keywords : Scylla serrata, growth, moulting, snail temberungun

Mangrove crab (Scylla serrata) is a fishery commodity that has high economic value. The supply of mangrove crabs in Indonesia is still dominated by wild catches. One of the places to catch mangrove crabs is in the Mangrove Area of ​​Deah Raya Village, Syiah Kuala District, Banda Aceh, Indonesia. Mud crabs are very susceptible to infestation by pathogens in their environment. Pathogens that are often found infesting mud crabs are parasites. Ectoparasite attacks are very dangerous for mud crabs because they can damage the body organs of mud crabs. Therefore, this research was conducted to determine the level of intensity and prevalence of ectoparasites in mud crabs (Scylla serrata) caught by fishermen in Deah Raya Village. This research uses a survey method with a purposive sampling method. Ectoparasite examination is carried out using the smear method. This research was conducted at the Hatchery Laboratory of the Faculty of Maritime Affairs and Fisheries in May 2024. Thirty crabs (Scylla serrata) were randomly sampled from the mangrove area in ​​Deah Raya Village, Syiah Kuala District, and observed for the presence of ectoparasites. The observations revealed that the crabs were infested by ectoparasites from the protozoa phylum (such as Zoothamnium sp., Epistylis sp., and Vorticella sp.) and from the arthropod phylum (Octolasmis sp.). Infestation by Zoothamnium sp. was found as the most prevalent (n=15, 50%), followed by Epistylis sp. (n=6, 20%), Vorticella sp (n=3, 10%), and Octolasmis sp (n=3, 10%). The infestation intensity for Zoothamnium was 7.5 individuals per crab, Epistylis sp. 5.0 individuals per crab, Vorticella sp. 2 individuals per crab, and Octolasmis sp. 1 individual per crab. Considering the high prevalence and intensity of Zoothamnium sp. in the mangrove crabs, the mitigating efforts can be focused on this ectoparasite.

Mud crab is one of brackish water commodity with high ecological and economical value, which is a lot of demand from the local, regional and also foreign market. This study aims to determine autotomi induction effect on the survival rate, molting, and growth of the mud crab (Scylla serrata, Scylla tranquebarica, and Scylla paramamosain). This research was conducted in November-January 2013, which is located in the traditional ponds in Anggoeya Village, Poasia District, Municipality of Kendari, Southeast Sulawesi. It used a completely randomized design (CRD) with 3 treatments and 3 replications, thus in this study, theirs 9 units of experiments which each experimental unit consisted of 10 crabs test. Treatment was applied in this study is the autotomi induction treatment on the mud crab S. paramamosain, S. tranquebarica, and S. serrata. Data were analyzed by analysis of variance (ANOVA). If the results showed the significant effect, it would proceed by the least significant difference (LSD) at the 95% confidence level (α = 0,05). As a tool to carried out the statistical tests were used the SPSS version 17.0 program package. The results showed that autotomi induction treatment on the different types significantly the different results (p<0,05) to the survival rate and molting perfection, but it was not significantly different (p>0,05) to the absolute growth and molting period of the mud crab (S. paramamosain, S. tranquebarica, and S. serrata).

The mangrove pens were modified to produce mud crab (Scylla serrata) and milkfish (Chanos chanos) in a polyculture system. The modification of mangrove pens was done by adding excavations inside the pen. The water quality parameters (dissolved oxygen (DO), pH, salinity, and temperature) were monitored, and the recovery and production rates in each pen were evaluated. The experiment was conducted for a rearing period of 143 days in nine mangrove pens, each having an area of 32 m2 and an average net enclosure height of 3 m from the soil surface. The three different pens constructed (existing design: canal only, 43% excavation by area, and 54% excavation by area) were designated as T1, T2, and T3, respectively. The water quality parameters recorded in the pens were favorable for the growth and recovery of the mud crab and milkfish, except for DO. For mud crab, the highest mean recovery was recorded in T2, followed by T3, and the lowest in T1. The production rate followed the same pattern as the recovery, with T2 having the highest, followed by T3, and T1 having the lowest. The statistical analysis revealed that the variations in mud crab recovery were not significant, while in terms of production rate, modified mangrove pens were found to be more effective than the existing design. Due to the total mortality of the cultured milkfish, the current set-up of modified mangrove pens was found to be unsuitable for the polyculture system of milkfish and mud crab production.

This study aims to know various types, prevalence, and intensity of ectoparasite on mud crab (Scylla serrata) in Mangrove Forest Wonorejo, Surabaya. This study used survey method with random sampling to collect the data. This study was conducted in November 2020. Ectoparasite in this study collected by smear method. In-situ water quality measurement were applied in this study. Mud crab (Scylla serrata) in this study was obtained from local fisherman that consist of 30 crabs. There are 3 types of ectoparasite was infected mud crab there are Octolasmis sp. (208 ind), Zoothamnium sp. (93 ind), dan Epistylis sp. (116 ind). Those ectoparasite was found in mud crabs gills. The highest prevalence was Octolasmis sp. (70%), Epistylis sp. (30%), Zoothamnium sp. (23%). The highest intensity was Zoothamnium sp (13,29 ind/crab), Epistylis sp. (12,89 ind/crab), dan Octolasmis sp. (9,90 ind/crab). Based on Ministerial Decree of Ministry Environment and Forestry No. 1 of 2004 water quality in Wonorejo Mangrove Forest was still optimal for life cycle of mud crab with average of temperature is 31,20°C, Dissolved Oxygen 5,53 mg/l, salinity 11 ppt, and pH 7,40.

Abstract. Hastuti YP, Rusmana I, Nirmala K, Affandi R, Tridesianti S. 2019. Identification and characterization of nitrifying bacteria in mud crab (Scylla serrata) recirculation aquaculture system by 16S rRNA sequencing. Biodiversitas 20: 1339-1343. Recirculation is one of the systems used for increasing aquaculture production, for example, is mud crab Scylla serrata culture. Aquaculture activities will produce organic nitrogen waste and can be affected to inorganic condition (nitrification bacteria). Nitrifying bacteria are capable of changing aerobically from NH4+ to NO2-(nitrite) and from NO2-to NO3-(nitrate). This current work aimed to identify and characterize nitrifying bacteria in mud crab (S. serrata) culture with a recirculated system. Nitrifying bacteria were isolated using serial dilution (10-1 until 10-5) of open filter FB water sample previously cultured in a specific medium. Bacterial identification was performed using a procedure of PrestoTM Mini gDNA Kit (Geneid) for DNA extraction and Polymerase Chain Reaction (PCR) primer 63F and 1387R for 16S rRNA gene amplification. Molecular identification using 16S rRNA sequences, the nitrifying bacteria isolated from mud crab recirculation aquaculture system were 99% identified as a group Pantoea calida, Pseudomonas stutzerii dan Halomonas sp. Morphological characterization of the colony morphology showed that a mucoid appearance and appeared cream in color and large size. Furthermore, their cells were recognized as basil and Gram-negative.

Nutritional properties of wild and fattening mud crab (Scylla serrata) in the south-eastern district of Bangladesh

One of the fishery commodities in the mangrove forest area that has the potential to be cultivated in the mangrove crab (Scylla serrata). The local and international market demand for soft shell mud crab from year to year tends to increase. Most of the efforts to meet the needs of softshell crab still rely on catches from nature where availability is uncertain. The purpose of this study was to identify the effect of the long molting time of mud crab (Scylla serrata) fed trash feed and feed fed with spinach extract using natural methods and popeye. This research is experimental using a completely randomized design. The treatments consisted of the natural method with trash feed, the natural method with spinach extract feed, the popeye method with trash feed, and the popeye method with spinach extract feed. The crabs used are mud crabs with the hard carapace. The test parameter is the length of time for mud crab molting, which is calculated starting from the hard-shelled crab to molting. The data obtained in the form of differences in the length of time for mud crab molting using various treatments were analyzed descriptively quantitatively. The results of this study indicate that the popeye method with spinach extract feed is the treatment that produces the best molting time, which is 14-21 days compared to other treatments.

Mangrove crab or known as Scylla sp. is one of the biota whose habitat is in coastal waters, especially in mangrove forest areas. The need for mangrove crabs still largely relies on natural catches that are fluctuating. For this reason, it is necessary to cultivate mangrove crabs in a controlled manner that can support an effective, efficient and economically profitable mangrove crab farming business. Cultivation can increase mangrove crab production to meet domestic and foreign market demand. An alternative that can be chosen for mangrove crab cultivation is an apartment system that is arranged vertically in the form of a storage rack. The water medium used in this apartment system cultivation uses a recirculation system. One of the efforts to accelerate the growth of crabs is by using steroid hormones. Ecdysteroid is the main steroid hormone that has the main function as a skin replacement hormone. In addition, this hormone also regulates physiological functions, such as growth, metamorphosis, and reproduction. Therefore, this study was conducted to determine the effect of using fern leaf extract (Diplazium esculentum) in raw fish feed with different doses on growth and feed conversion ratio in mud crabs. This research method uses a field experimental method with a completely randomized design (CRD) consisting of 5 treatments and 3 replicates with different percentage doses, namely: PA: Percentage of 0 ml/Kg, PB: Percentage of 100 ml/Kg, PC: Percentage of 125 ml/Kg, PD: Percentage of 150 ml/Kg, PE: 175 ml/Kg percentage. The results showed that the use of fern leaf extract in mangrove crab (Scylla serrata) feed had a significant effect on the growth of absolute weight, Absolute Length, SGR (Specific Growth Rate) and FCR (Feed Conversion Ratio) where the most influential treatment was treatment E which was the highest dose of 175 ml/Kg. This indicates that treatment E is the best dose treatment for growth and feed conversion ratio of mud crab (Scylla serrata).

Mud crab Scylla serrata of Kotania Bay and Pelita Jaya Bay of Western Seram District, has been harvested by local fishermen for more than 25 years. The mud crab has high economic value, and there is always a market for this fishery. The economic dependence of the fishermen forces them to harvest this resource extensively. No existing management strategy and extensive exploitation leads to unsustainable conditions of this fishery. With inadequate data condition, the Driver-Pressure-State-Impact-Response (DPSIR) model constructs an ecological, social-economy, and institutional conceptual model framework for sustainable management of this fishery. The driving force (D) in this fishery comes from the local fishers harvesting the mud crab. The two most sensitive attributes that affected mud crab sustainability from Rapfish analysis were used as state-level of DPSIR methodology. The result shows that the most sensitive variables from ecological, socio-economy, and institution were: caught before maturity, mud crab size, consumer attitude towards sustainability, just management, government quality, and monitoring and reporting, respectively. It was concluded that this conceptual model allows a better understanding of how the mud crab S. serrata system works and management actions taken at different system components. This conceptual model framework can be a useful tool to incorporate the participation of stakeholders, managers, and scientists in the process of a sustainable management plan.

Mud crab (Scylla serrata) have potency commercial market in this country and the other country. That thing because mud crab (Scylla serrata) flesh has a delicious taste and high nutrition. People haven’t knowed about cholesterol content in both male or female mud crab (Scylla serrata), whereas the knowledge about cholesterol content is important to consider nutrition intake to keep in good health. This research aim to determine cholesterol content in Scylla serrata by observing male and female crab in Pemalang and Demak. This research used descriptive method and sampling used purposive random sampling method. Determination of sampling position used purposive sampling method. This research has done in October 30th – November 25th 2011. This research used 30 male and 30 female with mean body weigh 60 - 100 g. Analysis of cholesterol content used method by Lieberman–Burchad. Result from this research indicates that S. serrata from Pemalang has cholesterol content more large than S. serrata from Demak, while the male crab from both place has higher cholesterol content than female crab (66,67 mg/100g and 61,67 mg/100g in male crab, and 64,67 mg/100g and 58,33 mg/100g in female crab).

Mud crab (Scylla serrata) is one of small scale fisheries commodity that have high economic value and typically associated with good mangrove ecosystem. A habitat degradation will cause a serious impact on the existence of mud crab population. The puropse of this study was to assess the ecological quality of mud crab habitat condition on Bintan Bay’s mangrove ecosystem. Ecological data collection was conducted by using plots line transect for mangrove and the mud carb data collection by using fishermen catch (fisher based survey). The results showed the value of habitat quality index (HQI) of mud crab (Scylla serrata) ranged from 52-82 which mean in the “moderate” category (index value 43-66) and "good" (index value 67-90). It showed that Bintan Bay’s mangrove ecosystems was good enough to support the viability of mud crab. Habitat quality had a linier impact on body weight gain (R2 = 99.78%) and carapace width (R2= 99.21%). This showed that higher the index value of habitat quality, the size of the body weight and carapace width will increases. Keywords: Scylla serrata, habitat quality, ecology, mangroves, and Bintan Bay

Grow-out culture of mud crabs Scylla serrata in East Africa is at an earlier development phase and is dependent on wild seed crabs. We assessed three different culture systems (net cages, ponds and pens) in three treatments (shelter, size and density) to evaluate survival and growth in small-scale culture of mud crabs in Kenya. In small nursery cages, we assessed how availability of shelter, stocking density and size-class separation affected cannibalistic rates in small juveniles (20-80 mm internal carapace width) in 7-day experiments. The result indicated that shelter and size-class separation decreased cannibalism and mortality with 26 and 31 %, respectively, whereas no significant effect was found for different stocking densities. Earthen ponds and mangrove pens were used to compare growth and survival in long-term studies (2-4 months) in the presence and absence of shelter. Treatments with and without shelter yielded low overall recovery of crabs (4-26 %) indicating high mortality rates, and there was no significant effect of shelter or culture system on survival. In contrast, growth rate was high in both pens and ponds, but significantly lower in pen systems without shelter. Generally, the results indicated that cannibalism is the largest source of mortality in different culture systems (net cages, ponds and pens), and use of shelter and size grading of crabs improved survival significantly. In contrast, growth rates were high and comparable to natural growth in both pond and pen culture when shelter was provided. Using growth models to compare growth and survival in mud crabs from aquaculture studies in the literature, we show that shelter may have a stronger effect on growth than has been previously thought, whereas crab density appears to impact more on crab survival. Thus, improving survival in grow-out culture systems is a challenge that remains to be solved for small-scale mud crab culture in East Africa.

Abstract. Karniati R, Sulistiyono N, Amelia R, Slamet B, Bimantara Y, Basyuni M. 2021. Mangrove ecosystem in North Sumatran (Indonesia) forests serves as a suitable habitat for mud crabs (Scylla serrata and S. olivacea). Biodiversitas 22: 1489-1496. Mud crabs (Scylla serrata and Scylla olivacea) are often found in muddy substrates associated with mangrove vegetation. The habitat of these crabs ranges from tropical estuaries to sheltered subtropical areas, riverbanks, lower river traits, and intertidal areas. These crabs have an important economic value, and it increases the income of the communities living around the mangrove area. This study aims to obtain more information on the environmental factors of habitat for mud crabs (S. serrata and S. olivacea): insights on the effects of abiotic and biotic factors and potential economic value, in the village of Lubuk Kertang, Langkat, North Sumatra, Indonesia. Data were collected by measuring abiotic factors (temperature, pH, salinity, dissolved oxygen, mud depth, distance from the river) and biotic factors (mangrove stand density through canopy cover). The dataset was analyzed using a binary logistic regression analysis with a stepwise method. Results showed that the abiotic factors that contributed to the presence of the mud crab were dissolved oxygen and a mud depth of 68.7%. Meanwhile, the remaining 31.3% that contributed to the presence of mud crabs were abiotic factors (temperature, pH, salinity, distance from rivers) and biotic factors (stand density through canopy cover). The present study suggests that dissolved oxygen and mud depth have an important function in predicting the presence of mud crabs.