Conversion of Nitrogen and Phosphorus in Jellyfish into an Inorganic Species and Processing Jellyfish as Fertilizer

We have investigated the conversion rate of organic nitrogen into NH4+(ammonium), NO2-(nitrite), and NO3-(nitrate), and that of organic phosphorus into PO43-(phosphate) in jellyfish during storage at room temperature. Jellyfish, such asAurelia aurita, Chrysaora melanaster, andStomolophus nomurai, were stored in glass or plastic containers. Supernatant solutions of the jellyfish were periodically taken from the containers and centrifuged and filtered. NH4+and PO43-in the filtrate were determined using conventional absorptiometry. Capillary zone electrophoresis (CZE) developed by us was used to determine the concentrations of NO2-and NO3-. After 10 days, 79% of Total-N (total nitrogen) and 60% of Total-P (total phosphorus) were contained in the supernatant solution ofA. auritaas NH4+and PO43-, respectively. On the other hand, 81% of Total-N and 74% of Total-P were contained in the supernatant solution ofC. melanasteras NH4+and PO43-, respectively after 20 days. After 60 days, 97% of Total-N and 93% of Total-P were contained in the supernatant solution ofA. aurita; 93% of Total-N and 100% of Total-P forC. melanaster. NO2-and NO3-concentrations in the jellyfish were lower than 0.8 mg/l within 60 days. The dried precipitate was weighed to reveal the transparency of the supernatant solutions. The amount of suspended solid in the supernatant solutions was≤0.01%(w/w) after 10 days. As a result of storing jellyfish for more than 60 days in other experiments, the longer the storage time, the higher the concentration of NH4+and PO43-in the supernatant solutions and transparency. We also proposed a concentration procedure for the supernatant solutionsin vacuo(70 hPa) at 40°C to reduce the amount of Na+(sodium) in the solutions and those volumes. The former is to decrease the possibility of salt injury for plants and the latter is to decrease the cost of transfering fertilized jellyfish to consumption places such as vegetable fields. Jellyfish suspensions were diluted as an alternative procedure to relieve the salt injury. Vegetables were cultivated using the diluted suspensions. The usefulness of jellyfish as a liquid fertilizer was elucidated through the experiments.