<p class="NoParagraphStyle" align="center"><strong>ABSTRACT</strong></p><p class="NoParagraphStyle" align="center"> </p><p class="NoParagraphStyle">One of the abiotic factors that affects the growth and the survival of crabs is salinity. The optimum salinity media will give maximum impact on mangrove crab <em>Scylla serrata</em> due to the osmoregulation process. This study aimed to examine the effect of salinity on the survival rate (SR) and spesific growth rate (SGR) of mangrove crab through the reaction of physiological condition. The treatments were rearing mangrove crab at the salinity medium of 15 ppt (A), 20 ppt (B), 25 ppt (C), and 30 ppt (D). Result showed that different salinity performed a significant effect (P&lt;0.05) on the survival rate and specific growth rate of the crabs. The low level of stress, shown by the high value of total hemocyte and the low osmotic pressure, has made salinity of 25 ppt was the optimum condition for the mangrove crab rearing.</p><p class="NoParagraphStyle"> </p><p class="NoParagraphStyle">Keywords: salinity, survival, specific growth rate, mangrove crab</p><p class="NoParagraphStyle"> </p><p class="NoParagraphStyle"> </p><p class="NoParagraphStyle" align="center"><strong>ABSTRAK</strong></p><p class="NoParagraphStyle"> </p><p class="NoParagraphStyle">Salah satu faktor abiotik yang memengaruhi pertumbuhan dan kelangsungan hidup kepiting adalah salinitas. Salinitas media optimum akan memberikan efek yang maksimal pada kepiting bakau <em>Scylla serrata</em> sehubungan dengan proses osmoregulasi tubuhnya. Penelitian ini bertujuan untuk menguji pengaruh salinitas pada kelangsungan hidup dan laju pertumbuhan spesifik kepiting bakau melalui reaksi kondisi fisiologis. Penelitian ini terdiri atas perlakuan salinitas media 15 ppt (A), 20 ppt (B), 25 ppt (C), dan 30 ppt (D). Hasil penelitian menunjukkan bahwa perbedaan salinitas media pemeliharaan kepiting bakau memberikan perbedaan nyata (P&lt;0,05) pada kelangsungan hidup dan laju pertumbuhan spesifik kepiting bakau. Rendahnya tingkat stres pada salinitas 25 ppt dijelaskan dengan tingginya jumlah total hemosit dan rendahnya tekanan osmotik sehingga salinitas 25 ppt merupakan kondisi optimum bagi pemeliharaan kepiting bakau.</p><p class="NoParagraphStyle"> </p><p>Keywords: salinitas, kelangsungan hidup, laju pertumbuhan spesifik, kepiting bakau</p>

Salah satu faktor abiotik yang berpengaruh terhadap pertumbuhan dan kelangsungan hidup kepiting bakau adalah suhu. Media suhu yang optimum memberikan dampak pertumbuhan yang maksimum pada kepiting bakau Scylla serrata karena berkaitan dengan proses metabolisme. Penelitian ini bertujuan untuk menguji pengaruh suhu terhadap kelangsungan hidup (SR) dan laju pertumbuhan bobot harian (SGR) kepiting bakau melalui reaksi kondisi fisiologisnya. Penelitian ini terdiri dari perlakuan media bersuhu 25 °C (A), media bersuhu 27 °C (B), media bersuhu 29 °C (C), dan media bersuhu 31 °C (D). Berdasarkan hasil penelitian yang diperoleh suhu 29 °C merupakan suhu terbaik untuk pemeliharaan kepiting bakau dengan sistem resirkulasi, hal ini dapat dilihat dari hasil rasio konversi pakan, pertumbuhan spesifik dan kelangsungan hidup kepiting bakau yang memiliki nilai terbaik dibandingkan perlakuan lainnya.

The development of technology and production systems in the field of aquaculture is one of the primary solutions for increasing production to cope with the presence of fishing is mainly about stripped catfish seed. Seed quality improvement through lime addition for the availability of minerals in the water supply and maintenance of media in salinity 4 g/L which aims to suppress the level to support availability of employment of the inaugural thereby reducing energy used for osmoregulation and can be allocated to growth of catfish. Catfish seed size used was 2.69±0.04 cm and weight used was 0.08±0.01 g. Aquarium used measuring 30 x 15 x 25 cm by as much as 15 units and filled water in salinity 4 g/L as much as 9 litres per unit and added lime CaCO3 according treatment that was K (0 mg/L CaCO3), A (150 mg/L CaCO3), B (200 mg/L CaCO3), C (250 mg/L CaCO3) and D (300 mg/L CaCO3). For research, fish was fed on of a protein (28%) as much as 3 times a day by FR 5%. The addition of CaCO3 treatment for all treatment generated a level of survival as much as (100%) (P>0.05). While growth rate of weights daily each treatment in a consecutive manner that is (11.34%); (12.06%); (11.51%); 12.67%; and (11.58%) (P>0.05). Absolute value of different length produce 2.84 cm; 4.63 cm; 3.23 cm; 3.79 cm; and 3.28 cm (P>0.05). During the research, the quality of the water was in the range that can be tolerated by the seed of catfish. The use of lime CaCO3 on salinity 4 g/L recommended as much as 250 mg/L CaCO3 with a turn of the water at regular intervals and feeding.

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.

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 <0.05). Addition of six shelters could optimize the growth of mud crabs with a stocking density of 10 crabs in one culture box.

Molting phase is one of many factors that can inhibit mudcrab growth. Recirculation system in culturing mudcrab has a weakness which is the decreasing of ions. Calcium and magnesium in the water can affect the molting phase. The aim of this study was to evaluate the best additional frequency of calcium and magnesium in recirculation system. This research used mudcrab seeds that have weight of 54.

This study used Lemna as phytoremediator plant in red tilapia culture system and given as feed additive among treatments. The purpose of this study was to measure the production performance (quantity and quality) and physiological response of red tilapia. Study was conducted with two treatments: TL (without lemna) and L (with lemna) treatment. The results showed that L treatment gave the best result based on better feed convertion ratio. However there are no significant difference found in organoleptic test, growth performance, and blood cholersterol parameters. In addition, optimum water quality media that stimulated by lemna, can create a comfortable environmental conditions for red tilapia.

<p>Heavy metals are serious pollutants of the aquatic environment because of their environmental persistence and ability to be accumulated by aquatic organisms. <em>Oreochromis niloticus </em>exposed to 0, 0.16, 0.5, and 1.0 ppm Hg for 30 days. The aim of this study was to determine the influence of mercury in water on survival rate, growth rates, hematological, and histological parameters of <em>Oreochromis niloticus</em>. This study was conducted from Mei to June 2009. The experimental design was arranged in completely randomized design with four treatments and three replications. Stock density was 8 fish/aquarium with mean initial body weight was 15.70±1.13 g. Growth and survival rates of test fish were decreased with increasing the Hg concentration. Red blood cell (RBC) count, haematocrit content, and haemoglobin content decreased when compared to the control. The number of white blood cells (WBC) increased in mercuric treated fish. The results are statistically significant at p&lt;0.05 level.</p> <p>Keywords:mercury, survival and growth rate, hematology, histopathology, <em>Oreochromis niloticus</em></p>