Effects of Seed Transfer Distance on Production Success of Mud Crab (Scylla serrata) in Recirculating Aquaculture Systems

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.

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).

Mud crabs ( Scylla serrata ) are highly valued aquaculture commodities in the international market. However, feeding operations in mud crab culture using a Recirculating Aquaculture System (RAS) are often inefficient, increasing labor time and operational costs. This study aimed to evaluate the operational efficiency of feeding S. serrata once, twice, and three times per day by assessing production performance and conducting a business analysis in a RAS apartment system. A completely randomized design was used with three feeding frequency treatments (one, two, and three times daily), each with three replicates. Parameters observed included survival rate, absolute weight gain, carapace length and width growth, molting frequency and percentage, feed consumption, feed conversion ratio (FCR), feed utilization efficiency, and labor efficiency. Results showed that feeding frequency had no significant effect on survival rate, growth parameters, molting performance, or feed utilization efficiency. However, feeding twice per day produced the highest profit (IDR 5,342,008) and a labor efficiency of 1.08%. These findings indicate that feeding twice daily optimizes both biological performance and economic returns in mud crab fattening using a RAS apartment system.

Mud crabs (Scylla serrata) are important coastal fishery commodities and fetch a high market price, especially for soft-shell crab, making them a lucrative option for aquaculture. However, the main challenges in mud crab culture are their aggressive behavior, which causes more mortality due to cannibalism, resulting in a decrease in overall production. This study aimed to investigate the effects of different synthetic substrates and find a better substrate for optimal growth, survival, molting, cannibalism, and immune response of mud crab instars in the Recirculating Aquaculture System (RAS). The experiment consisted of four treatments: CR: without substrate; T1: shade net substrate; T2: shredded rope substrate; and T3: PVC pipe substrate, conducted in RAS for 30 days with a stocking of 20 crab instars: carapace width of 0.483 ± 0.02 cm in each tank, with triplicate. The mud crab instars reared in T2 had the highest (P < 0.05) specific growth rate (5.17 ± 0.62%) and total hemocyte counts (5.55 ± 0.21 × 106 cells/mL). Survival and molting success were significantly greater in T2 (65 ± 6.0%; 85 ± 5%) and T3 (71.7 ± 5.8%; 76.7 ± 2.9%). Net biomass gain was also highest in T2 (19.98 ± 4.27 g) and T3 (17.66 ± 2.59 g) compared to the other groups. These findings demonstrate that synthetic substrates, particularly shredded rope and PVC pipes, effectively enhance survival and net biomass in mud crab instars RAS culture, providing practical guidance for nursery management through habitat manipulation using suitable synthetic substrates that mimic natural conditions, enhancing mud crab instars production.

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).

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.

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.

Persistent organochlorines and metals in estuarine mud crabs of the Great Barrier Reef

This study aimsed to determine the type of ectoparasites on crab (Scylla serrata) in the water of Alue Naga Banda Aceh. The samples of this study were 10 heads of mud crabs were taken from the Alue Naga waters Banda Aceh and taken to the Laboratory of Parasitology. Veterinary Medicine Faculty of Syiah Kuala University Banda Aceh to identify the take ectoparasites on mud crab (Scylla serrata) by observing the outer body of the organism, then noted bleeding, wounds or swelling and pay attention to the type of organism that is attached to the body of mud crab, then dredge the outer parts of the body like the carapace, foot path, foot pool and gills were take it and then tweezers and then putting the object glass that has been provided and observed with a microscope with 100 times magnification and see what kind of ectoparasites that have been found and then compare with the identification key. From the results of this study concluded that ectoparasites which infects mud crab (Scylla serrata) in the waters of Alue Naga Banda Aceh come from genus Chilodonella sp. Whichare predilections in the gills with a prevalence rate of 10%.

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.

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.

Recirculating Aquaculture System (RAS) was chosen as an alternative for sustainable and low-impact mangrove crab cultivation. One of the main challenges in using RAS is determining the optimal feeding frequency. Inappropriate feeding can cause slow growth, increased mortality, and decreased water quality. This study aimed to analyze the effect of trash fish feeding frequency on the growth of mangrove crab (Scylla serrata) reared in RAS. The method used is an experimental method with a completely randomized design of 3 treatments and 4 replications. The research treatments tested were the frequency of feeding with FPP 01 once a day at 10 pm; FPP 02 twice a day at 10 pm and 5 pm; FPP 03 three times a day at 10 pm, 8 am and 5 pm. The parameters observed were survival, weight growth, carapace length growth, carapace width growth, specific growth rate and molting rate. The research data were analyzed using analysis of variance at a 95% significance level. The results showed that the frequency of feeding did not significantly affect the growth and survival of mud crabs in RAS. The frequency of feeding once is optimal to achieve maximum growth in mud crab cultivation using the RAS system with a survival rate of 100±0.00%, weight growth of 52.00±21.17 g, carapace length growth of 1.90±0.87 cm, carapace width growth of 1.60±0.70 cm, specific growth rate of 5.04±0.14%/day and molting rate of 67.00±0.58%.

Heavy metal accumulation and transfer from sediments to edible mud crab organs (Scylla serrata) pose major ecological and health risks to consumers. The bioaccumulation of these metals are detrimental if they are extremely toxic. The objectives of this study were to analyze heavy metal concentrations in sediments and crab organs and determine the transfer of heavy metals in Scylla serrata from sediments in Mida Creek, Kilifi. The crab samples were collected by simple random sampling whereas sediment samples were collected by purposive sampling. The transfer factor of heavy metals from sediments to the organs of edible mud crabs (Scylla serrata) was evaluated in both the wet and dry seasons. The measurements and examinations of heavy metals, samples of crab organs, and sediments were obtained from three sampled sites. The concentration of metals in the samples was determined using an X-ray fluorescence (XRF) spectrometer. The results showed that the majority of the components are accumulated by the crabs from sediments. The order in which the metal transfer factor to crabs from station 1 sediments increased was Fe &gt; Zn &gt; Ni &gt; Cu &gt; Cd &gt; Hg. In station 2, the transfer factor increased in the following order: Fe &gt; Zn&gt; Cu&gt;Ni&gt;Cd&gt; Hg, while in station 3, it increased in the following order: Fe &gt; Ni&gt; Zn&gt;Hg&gt;Cd&gt;Cu. The study concluded that mud crabs in Mida Creek actively absorb most of the elements from the sediments. The study recommends a routine monitoring of heavy-metal levels in other crustacean marine biota, and fish is necessary.

The availability of shelters in a specific density is expected to increase the production of mud crabs (Scylla serrata) in a recirculation system. Shelter, as one of the abiotic factors, plays a pivotal role in reducing death caused by cannibalism of crab and suppressing the stress levels of biota. Recirculation Aquaculture System (RAS), with the culture box capacity 60 L supported by the shelters, is predicted to produce the best physiological and growth responses of mud crabs. This present study aims to evaluate the effect of shelter addition in the environmental recirculation system on the physiological responses and production of mud crabs S. serrata with a density of 10 crabs per one culture box containing 60 L of seawater. The research was set up with three treatments of shelter addition, i.e., two shelters (S2), four shelters (S4), six shelters (S6), and control without shelter (C). Results showed that S6 was the best treatment with a survival rate of 73.33 ± 5.8%, a specific growth rate of 0.886 ± 0.014%, the growth rate of carapace width 0.024 ± 0.004 cm/day, and the lowest feed conversion ratio than those of other treatments. S6 treatment significantly influenced the total hemocyte count of crabs at the early cultivation (P &lt;0.05). Addition of six shelters could optimize the growth of mud crabs with a stocking density of 10 crabs in one culture box.

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