Pengaruh Induksi Autotomi pada Kepiting Bakau (Scylla serrata, Scylla tranquebarica, Scylla paramamosain) terhadap Sintasan, Molting, dan Pertumbuhan di Tambak Rakyat Kelurahan Anggoeya Kendari-Sulawesi Tenggara

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).

Simple SummaryThe eyestalk is a key organ in crustaceans that produces neurohormones and regulates a range of physiological functions. Eyestalk displacement was discovered in some first-generation (F1) offspring of the novel interspecific hybrid crab (Scylla serrata ♀ × S. paramamosain ♂). To uncover the genetic mechanism underlying eyestalk displacement and its potential implications, high-quality transcriptome was reconstructed using single-molecule real-time (SMRT) sequencing. A total of 37 significantly differential alternative splicing (DAS) events (17 up-regulated and 20 down-regulated) and 1475 significantly differential expressed transcripts (DETs) (492 up-regulated and 983 down-regulated) were detected in hybrid crabs with displaced eyestalks (DH). The most significant DAS events and DETs were annotated as being endoplasmic reticulum chaperone BiP and leucine-rich repeat protein lrrA-like isoform X2. In addition, the top ten significant gene ontology (GO) terms were related to the cuticle or chitin. Overall, this study highlights the underlying genetic mechanisms of eyestalk displacement and provide useful knowledge for mud crab (Scylla spp.) crossbreeding.The lack of high-quality juvenile crabs is the greatest impediment to the growth of the mud crab (Scylla paramamosain) industry. To obtain high-quality hybrid offspring, a novel hybrid mud crab (S. serrata ♀ × S. paramamosain ♂) was successfully produced in our previous study. Meanwhile, an interesting phenomenon was discovered, that some first-generation (F1) hybrid offspring’s eyestalks were displaced during the crablet stage I. To uncover the genetic mechanism underlying eyestalk displacement and its potential implications, both single-molecule real-time (SMRT) and Illumina RNA sequencing were implemented. Using a two-step collapsing strategy, three high-quality reconstructed transcriptomes were obtained from purebred mud crabs (S. paramamosain) with normal eyestalks (SPA), hybrid crabs with normal eyestalks (NH), and hybrid crabs with displaced eyestalks (DH). In total, 37 significantly differential alternative splicing (DAS) events (17 up-regulated and 20 down-regulated) and 1475 significantly differential expressed transcripts (DETs) (492 up-regulated and 983 down-regulated) were detected in DH. The most significant DAS events and DETs were annotated as being endoplasmic reticulum chaperone BiP and leucine-rich repeat protein lrrA-like isoform X2. In addition, the top ten significant GO terms were related to the cuticle or chitin. Overall, high-quality reconstructed transcriptomes were obtained for the novel interspecific hybrid crab and provided valuable insights into the genetic mechanisms of eyestalk displacement in mud crab (Scylla spp.) crossbreeding.

Mud crab (Scylla serrata) is a fishery commodity that has high economic value and has a wide salinity tolerance so that its growth can be developed. The growth of mud crabs can be influenced by genetic traits such as moulting. In cultivation activities there are methods that can accelerate the moulting process such as environmental engineering (increasing and decreasing the salinity of the maintenance media) and mutilation. This study aims to determine the growth and fastest moulting time of crabs in media with different salinities in controlled media. The method used is an experimental method with a Completely Randomized Design (CRD) consisting of 5 treatments and 3 replications, namely: (Control), (P1: 5 ppt), (P2: 10 ppt), (P3: 15 ppt) and (P4: 20 ppt) which are given to mud crabs for 45 days. The results showed that at 5 ppt salinity obtained the fastest moulting time which was 24.3 days and the longest was at 20 ppt salinity for 39 days, while the highest growth was obtained in the 15 ppt salinity treatment with an average absolute weight of 27.3 grams and the lowest was in the control treatment with an average absolute weight of 18.3 grams.

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).

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.

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.

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).

The high demand for mud crabs in North Kalimantan causes catch to increase in the wild. If it is not balanced with efforts to increase its aquaculture of mud crab, in the future there will be a decline in population. This study aims to determine the growth and survival rate of mud crab seed (crablet, Scylla serrata) in the application method of different types of trash fish. This research used a completely randomized design with 4 treatments and 3 replications. The Crablet used carapace width average 0.07-0.09 cm and weigh average 0.05-0.07 g with total 150 crablets. The treatments applied by trash fish were (A) Tilapia Fish (Oreochromis mossambicus), (B) Longfin Herrings Fish (Ilisha elongata), (C) Sword Fish (Trichiurus lepturus) and (D) Snails (Telescopium telescopium). The results were The best weight growth of crablet occurs in the treatment of T. lepturus (P>0.05) and the highest of survival rates of crablet were found in treatment T. telescopium (P<0.05) than the other. The trash fish were used turned out to be able survival of crablet mud crab (Scylla serrata).

High market demand of mud crab (Scylla serrata) encourages farmers to increase the production of mud crab. However, mud crab can not synthesize essential amino acids, so it is necessary to supply essential amino acids such as lysine and methionine in the diet. This study aims to determine the effect of lysine and methionine on feeds to increase growth and retention of mud crabs (Scylla serrata). In this study the amount of lysine amino acid and methionine added to the trash fish diet were: P0 (0: 0%); P1 (0.75: 0.75%); P2 (1: 1%); P3 (1.25: 1.25%); P4 (1.5: 1.5%) with the ratio of lysine and methionine 1: 1. The parameters observed in this study were Survival Rate (SR), Specific Growth Rate (SGR), Feed Conversion Ratio (FCR), Efficiency Feed (EF), protein retention and energy retention. The results of the 35-day maintenance study showed significant differences (P <0.05) against Specific Growth Rate (SGR), Feed Conversion Ratio (FCR), Efficiency Feed (EF), protein retention and no significant effect (P> 0.05) on energy retention and Survival Rate (SR) on mud crab. The best results in this study were found in P4 treatment with addition of lysine amino acids and methionine (1.5: 1.5%).

The aim of this study to find out the optimal level of salinity for the growth and survival of the mud crab (Scylla serrata). The weight of crab seeds were about 47.65-51.32 grams and the carapace length ranged from 64.35-71.30 mm, then put into 12 tanks (1 m x 1 m x 0.4 m) with a density of 4 crab seed per tank. During the maintenance of this test, mangrove crab was fed with fresh chicken intestines as much as 10% of its body weight per day. Water changes are carried out more than 150% per week. At the beginning of the experiment, each tank was conditioned to the same water salinity in all experimental units, namely 33 ppt. To see the effect of differences in salinity levels on the growth and survival of mud crabs, 4 treatments were made consisting of (A) 33 ppt salt content, (B) 31 ppt salt content, (C). The salt content is 29 ppt, and (D) the salt content is 27 ppt. From the results of this experiment, it is known that a decrease in the salt content of 4 ppt is the best treatment for the growth of mud crabs, but has no effect on the survival value.

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.

Report cards are increasingly popular tools communicating the condition of coastal and riverine environments to environmental managers, stakeholders and the public, and synthesising complex data drawn from a range of indicators. Mud crabs have not previously been included in ecosystem health report cards in Australia or elsewhere but have been suggested as environmental indicators for tropical coastal marine environments in Australia. Mud crabs support commercial, recreational and Indigenous fisheries and their biology is relatively well known. For these reasons and due to their local relevance, mud crabs (Scylla serrata) were selected for long-term monitoring and inclusion in a report card for Gladstone Harbour, Australia. Three mud crab measures were identified to reflect the variety of pressures across Gladstone Harbour: abundance, prevalence of rust lesions and sex ratio. A standardised field monitoring program was developed to allow for ongoing scoring and reporting of the multi-metric indicator. An indicator scoring (distance from benchmark) and grading methodology was applied to the indicator and refined over the two years of monitoring. This article provides a novel framework for monitoring and scoring mud crabs for management purposes or for use in report cards, and outlines the process of developing an indicator for an iconic crustacean species.