Effect of water salinity on survival and osmotic level of larval (Zoea Stage) of mud crabs Scylla tranquebarica

Mud crab of the genus Scylla are considered one of the most sought-after seafood today. This crab species has high quality and delicious aging growth rate and encourage expansion in the aquaculture sector especially in Southeast Asian Countries. However, salinity changes will cause changes in organisms osmotic pressure, and every aquatic biota has an optimal salinity range for survival. The study focuses on evaluating the effect of water salinity on the survival and osmotic levels of the purple mud crab, larvae of Scylla tranquebarica at the zoea stage. The LC50 assessment was performed in 10 different level of water salinity (0; 5; 10; 15; 20; 25; 30; 35, 40, and 50 ppt). Each treatment involved 20 ind./L of newly hatched crabs and being observed for 24 h in 10 different water salinity using 1 L volume glass container. The number of crab’s mortality were taken for each salinity regime. Larval behavior monitored during experiment. Meanwhile, the measurement of osmotic level was carried out at the salinity of 25, 30, and 35 ppt. The result shows that mud crab larvae exhibit any tolerance on the low salinity ranged from 0-10 ppt and the salinity of > 40 ppt. On the other hand, mud crab larvae were still able to survive at the salinity ranged from 20-40 ppt for more than 24 hours. The trend of the osmotic level of mud crab to survive is by hypo osmotic to iso osmotic.

Comparison of growth performance of live feed microalgae and rotifer (Brachionus sp.) under different feeding medium in outdoor culture condition

Live feed is the basic food source and nutrient security for successful seed production of any commercially important aquaculture species of fishes, mollusks and crustaceans. Both plant and animal originated aquatic microscopic organisms are generally termed as live food. They are the basic food items in early stages (larval stage) of life cycle due to small sizes, easy digestibility and enriched in nutrients. The Nannochloropsis sp.; Nannochlorum sp. and Tetraselmis sp. are rich with relatively high content of essential fatty acids in comparison to other marine algae. Likelihood, the rotifer Brachionus sp. is ideal feed item for brackishwater finfish and mud crab larvae rearing due to its special features like rapid reproduction, slow movement, suitable size and easy digestion by the newly hatched larvae. The present study is the report on comparison of growth performance of live feed (microalgae and rotifer) in outdoor culture condition. The study was conducted at the hatchery complex of Bangladesh Fisheries Research Institute, Brackishwater Station, Paikgacha, Khulna. In outdoor culture condition the growth pattern obtained for three microalgae were Tetraselmis sp.> Nannochlorum sp.> Nannochloropsis sp. Highest average growth 6.87×106±1.97×106, 6.91×106±1.69×106 and 6.23×106±1.53×106 was observed for Nannochloropsis sp., Nannochlorum sp. and Tetraselmis sp. respectively in trial 3. Average growth of rotifer (Brachionus sp.) found highest 189±18.10 ind./ml at combined media of yeast and microalgae and lowest growth 119.67±17.60 ind./ml noticed with baker's yeast media. Nannochloropsis sp. contains more energy among all microalgae but Tetraselmis sp. carry highest level of protein. The highest level of protein 56.3±0.18% found in rotifer enriched with microalgae+fish oil and lowest protein content noticed with microalgae enrichment media. So, research finding suggests that, treatment T3 would be the best recommendations for rotifer culture.

Effect of Basin Color on The Performance of Blue Swimming Crab (Portunus pelagicus)

Blue swimming crab (Portunus pelagicus) is a sea crab that is widely found in Indonesian waters. One of the determinants of the success of crab cultivation is the availability of quality seeds. Howewer, blue swimming crab hatchery is currently experiencing problems, namely unstable seed availiability due to high mortality and growth at the larvae stage. This research aims to evaluate the effect of various colors of rearing basins of feeding rate and survival rate of blue swimming crab larvae (P. pelagicus) in zoea stage. The larvae for the study was zoea-1 stage with a stocking density of 50 ind/L. The basins used in this study was a round plastic basin with a volume of 40 L filled with 30 L of media water. The feed used was rotifer and artemia nauplius. The method used was a completely randomized design consist of 4 treatments and 3 replications. The treatments that were the use black, green, blue, and red basins colors. The results of the analysis of variance showed that the color of the basins had a significant effect on the feeding rate (p < 0,05) and very significant on survival rate (p < 0,01) for small blue swimming crab larvae were produced in black basins 90.14 and 16.60%.

ANALISIS PEMBERIAN VITAMIN C PADA ROTIFER DAN ARTEMIA TERHADAP SINTASAN, RASIO RNA/DNA, KECEPATAN METAMORFOSIS DAN KETAHANAN STRES LARVA RAJUNGAN (Portunus Pelagicus) STADIA ZOEA

Penelitian ini bertujuan untuk menganalisis kandungan vitamin C rotifer, artemia dan larva rajungan setelah diperkaya dengan vitamin C dan menganalisis pemberian vitamin C terhadap sintasan, rasio RNA/DNA, kecepatan metamorfosis dan ketahanan stres larva rajungan stadia zoea. Serta menentukan dosis optimum vitamin C yang menghasilkan sintasan, rasio RNA/DNA, ke-cepatan metamorfosis dan ketahanan stres larva rajungan stadia zoea yang terbaik. Penelitian ini dilaksanakan pada bulan Mei sampai Juni 2020 di unit pembenihan kepiting dan rajungan Balai Perikanan Budidaya Air Payau (BPBAP) Takalar. Analisis Rasio RNA/DNA dilakukan di Laboratorium Uji Fisika Kimia BPBAP Takalar. Rancangan penelitian menggunakan Rancangan Acak Lengkap (RAL). Hasil penelitian menunjukkan bahwa pemberian vitamin C pada rotifer dan artemia dapat meningkatkan kandungan rotifer, artemia dan larva rajungan. Pemberian vitamin C pada rotifer dan artemia terhadap larva rajungan stadia zoea dapat meningkatkan sintasan, kecepatan metamorfosis dan ketahanan stres larva rajungan dan Dosis vitamin C 250 ppm yang terbaik pada pemeliharaan larva rajungan stadia zoea. This study aimed to analyze the content of vitamin C rotifer, artemia and small crab larvae after enriched with vitamin C and to analyze the provision of vitamin C to survival, RNA / DNA ratio, metamorphosis rate and stress resistance of crab larvae in zoea stage. Also, it aimed to determine the optimum dose of vitamin C which produces the best survival rate, RNA/DNA ratio, metamorphosis speed and stress resistance of crab larvae in zoea stage. This research was conducted from May to June 2020 in the hatchery unit of the Brackish Water Cultivation Fishery Center (BPBAP) Takalar. RNA / DNA ratio analysis was carried out at the Laboratory of Chemical Physics Testing of BPBAP Takalar. The research design used a completely randomized design (CRD). The results showed that giving vitamin C to rotifers and brine shrimp increased the content of rotifers, brine shrimp and crab larvae. Giving vitamin C to rotifers and artemia to larvae of zoea stadia crabs can increase survival, metamorphosis speed and stress resistance of crab larvae and the best dose of vitamin C 250 ppm in the maintenance of zoea stadia crab larvae.

PENGAYAAN PAKAN BENIH RAJUNGAN (Portunus Pelagicus) STADIA MEGALOPA MELALUI PEMBERIAN BETA KAROTEN

Penelitian ini bertujuan untuk meningkatkan nilai nutrisi pakan alami rotifer dan artemia melalui penambahan beta karoten yang bersumber dari wortel. Penelitian ini dilaksanakan pada bulan Mei 2020 di unit pembenihan kepiting dan rajungan Balai Pe-rikanan Budidaya Air Payau (BPBAP) Takalar. Rancangan penelitian yang digunakan adalah rancangan acak lengkap (RAL) sebanyak 4 perlakuan dan 3 ulangan. Hewan uji yang digunakan adalah larva rajungan (Portunus Pelagicus) stadia megalopa yang ditebar dengan kepadatan 5 ekor/l dan dipelihara sampai memasuki stadia crab. Luaran penelitian yang ditargetkan adalah teknologi pengayaan pakan alami rotifer dan artemia menggunakan beta karoten yang berasal dari wortel. Hasil penelitian menunjukkan bahwa Pemberian frekwensi pakan yang tepat setelah dikayakan dengan beta caroten akan meningkatkan sintasan dan pertumbuhan pada larva rajungan. Frekwensi pakan yang tepat diberikan pada larva rajungan yang terbaik untuk kelang-sungan hidup larva rajungan adalah pemberian pakan 3 kali/hari. This study aims to increase the nutritional value of natural rotifer and artemia feed by adding beta carotene from carrots. This research was conducted in May 2020 at the hatchery unit of the Brackish Water Cultivation Fishery Center (BPBAP) Takalar. The research design used was a completely randomized design (CRD) with 4 treatments and 3 replications. The experimental animals used were small crab larvae (Portunus pelagicus) in the megalopa stage which were stocked with a density of 5 individuals/l and they were kept until entering the crab stage. The target output of this research is natural feed enrichment technology for rotifer and artemia using beta carotene derived from carrots. The results showed that giving the right frequency of feed after being enriched with beta carotene would increase survival and growth in small crab larvae. The best frequency of feed given to small crab larvae for the survival of small crab larvae is feeding 3 times/day.

Mitochondrial Haplotypes suggest Genetic Component for Habitat Preference in Blue Crabs

Atlantic blue crabs (Callinectes sapidus) are ecologically and commercially fundamental. Life stages are punctuated with migration. Adults and juveniles live in estuaries and sounds. Larval stages develop in the coastal ocean. Juvenile and adult crabs occupy habitats from high salinities to fresh water. We determined whether maturing juvenile and adult blue crab habitat use is reflected in mitochondrial cytochrome oxidase 1 haplotypes. High salinity crabs had lower haplotype diversity (0.7260 ± .03900) compared to spawning crabs (0.9841 ± .00021) and low salinity crabs (0.94154 ± .00118). Significant pairwise differences in haplotypes were found between high salinity and spawning crabs (Nm = 0.26018, p < 0.001), and between high salinity and low salinity crabs (Nm = 0.19482, p < 0.001) indicating a lack of gene flow. Crabs from high salinity had highly significant genetic differentiation compared to spawning crabs (Fst = 0.11830, p < 0.001) and low salinity crabs (Fst = 0.09689, p < 0.001). Results support the hypothesis that genetics influence habitat selection. Crab larvae mix in the coastal ocean but occupy specific habitats upon return to sounds and estuaries. These findings have implications for the management of fisheries.

Spatial and Temporal Distribution of Blue Swimming Crab Larvae (Portunus pelagicus) in The Conservation Area of Betahwalang, Central Java

Betahwalang has been one of the main contributors to the Blue Swimming Crab (BSC, Portunus pelagicus) fisheries production in Central Java Province. Recruitment of the BSC depends to a large extend on the abundance of crab larvae. However, information on larval distribution of the crab affecting the recruitment to the fishery, fishery management and decision making to support crab conservation in Betahwalang area has been lacking. The purpose of this study is to describe the spatial and temporal distribution of BSC larvae in the crab conservation area, to identify the larval stage most commonly occurs in the conservation area, and to develop process of decision making to managing conservation areas. This study was conducted in twelve months, starting from January until December 2018. The spatial distribution of the crab larvae was analyzed and mapped by means of SPSS and ArcGIS. The results of this study indicate that the crab larvae occur in the conservation area throughout the year. The highest larval abundance of the crab occurs in May, September, and November. The most commonly found crab larval stages were megalopa. As megalopa and crablet stages are relatively much more active and closer to the adult form, their occurrence in the conservation area and throughout the year of 2018 suggests the existence of continuous support to the Blue Swimming Crab recruitment for the following year. The spatial and temporal distribution of the larvae were influenced by oceanographic parameters including temperature, nitrate and phosphate, which were associated with monsoonal changes in the Java Sea.

Design of Water Quality Monitoring System for Crab Larvae using IOT

Water quality is one of the determining factors in maintaining survival and growth of crab larvae, therefore we need a tool that can monitor water quality which includes temperature parameters, pH and salinity in real time and online in crab larva culture. This system consists of several sensor nodes with the main component being Arduino Uno which is connected by several sensor nodes as a publisher and Raspberry Pi 3 (RPi3) board as a broker. Data from each sensor node will be sent to brokers with different topics - and stored to a database using a wireless network. The application system used with the MQTT (Message Queue Telemetry Transport) protocol uses a red node. Red node will display data of each sensor node in the form of gauge and graph. In this study a water quality monitoring system was designed and developed. This tool uses the MQTT (Message Queue Telemetry Transport) protocol to display sensor node data in real time.