Organic nitrogen is the amount of nitrogen in organic materials dissolved or suspended in water. Ammonia, nitrite, and nitrate is a chemical product produced by organisms and bacteria through biological processes. Ammonia and nitrite are forms of nitrogen which have high toxicity to shrimp. High levels of nitrites can lead to disease such as IMNV and TSV. Based on the trigger factor, shrimp aquaculture component consists of:
According Snieszko (1974) disease in shrimp and fish are the result of the sum of shrimp condition, pathogen, and the square of the value of stress caused by environmental factors. Therefore, the most appropriate approach in controlling infectious diseases of environmental conditions.
Symptoms of diseases such as IMNV (Infectious MyoNecrosis Visus) usually occur at the age of DOC> 40 days. The disease has spread to almost all regions of Indonesia. Some shrimp aquaculture regions with a severe attack of infection such as: Bali, Banyuwangi, Situbondo, Southern part of West Java, West Lampung, and Bengkulu. The agent cause is the dsRNA of the Togaviridae family near the Genus Giardia virus. Signs of this disease shrimp blackened gills, white muscle, the progressive death of shrimp from a few up to thousands in a short time. Prevention efforts that can be done that is not excessive stocking density, organic matter input control, maintain water quality remains stable so that the shrimp are free of stress, and keep plankton abundance stable.
Water quality parameters which marked the beginning of infection for this disease are falling value of alkalinity (<100 mg / l), a decrease in plankton abundance drastically, the increase in the abundance of green Vibrio colony, TSS increased, decreased DO (2-3 ppm) and a pH less than 7, decreased TAN (<2 mg/L), and high Nitrite levels. In general, high levels of nitrites in waters to the serious effect of increasing the rate of oxygen consumption, Methaemocyanin compound formation, suppress the immune system of shrimp (susceptible bacteria Vibrio spp. pathogens), and increase the frequency of molting.
Organic materials from aquaculture produce ammonium load in the process of decomposition by heterotrophic bacteria. Ammonium is oxidized to nitrite and then into nitrate by bacteria through nitrification. Natural nitrification bacteria such as Nitrosomonas and Nitrobacter very limited water of the pond. Maintaining balance of bacteria and plankton abundance is very necessary to control contaminants. Therefore, the addition of bacterial inoculant right heterotroph needed to decompose organic matter and help the process of nitrification. One of the bacteria that has a function to maintain the balance of plankton and help the process of denitrification is in the Ariake 3 probiotics.
When very high nitrite levels heterotroph and nitrification bacteria can not work properly due to environmental conditions that support the growth of these bacteria decreased quality. Bacteria are similar to other living things, requiring nutrient intake as a source of energy (ATP) and cell growth. The main nutrients in the form of carbon (C), nitrogen (N), hydrogen (H), oxygen (O), sulfur (S), phosphorus (P), and a small amount of mineral micronutrients. Micro minerals needed bacteria in the form of zinc (Zn), cobalt (Co), selenium (Se), vanadium (V), iodine (I), iron (Fe), nickel (Ni), fluorine (F), copper (Cu) , chromium (Cr), molybdenum (Mo), manganese (Mn), stannum (Sn), and silicon (Si). The lack of sources of nutrients can affect the growth and abundance of bacteria will decrease.
These micro minerals are sufficiently available in seawater but with semi-closed until closed aquaculture systems so that the input of seawater into the pond is very limited. In addition, a high stocking density shrimp will produce a large waste load so that the required amount of bacteria that is a lot to decompose and the need for sufficient minerals. Therefore, the addition of macro and micro minerals is very important to maintain the stability of the abundance of decomposing bacteria so that infection can be avoided.
Nirmala K. 2019. Minimasi kadar nitrit di tambak udang dan rekayasa keseimbangan bakteri-plankton melalui pemenuhan kebutuhan mikro-elemen. Simposium Nasional Budidaya Udang Vannamei 2019 Banyuwangi.
Suantika G, Situmorang ML. 2018. Microbial equilibrium establishment through microbial loop manipulation for water quality and disease control in shrimp production. Microbial Biotechnology Research Group. School of Life Sciences and Technology. Institut Teknologi Bandung.