Raymee T. Tabobo, Zyra Grace C. Zaragosa (March 2012)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
Integrated Multi-trophic Aquaculture (IMTA) system has been proven to increase sustainability, economic output , and environmental remediation by providing the byproducts, including waste, from one aquatic species as inputs for another. In this study, potentials of high value species, Epinephelus fuscoguttatus (grouper), Crassostrea iredalei (Oyster), and Gracilaria bailinae (seaweeds) for an IMTA system for three months were investigated. The experiment included four treatments: IMTA, oyster-fish polyculture, seaweed-fish polyculture, and fish monoculture systems. Growth and survival of cultured organisms and their water biofiltration capabilities in terms of ammonia and phosphate uptake were assessed and compared among tanks. Significant differences among treatments were determined using One-way ANOVA. Results showed that IMTA system’s dissolved inorganic nutrient concentrations were significantly lower in the first eight weeks for ammonia and significantly lower for the first four weeks for phosphate compared with the fish monoculture. In the proceeding weeks, no significant differences were noted in the ammonia and phosphate concentrations among tanks. Growth rates of grouper were highest in IMTA tanks during the first month but no significant difference was noted among treatments. Growth increment of oyster was higher in IMTA tanks but there was no significant difference between treatments. Survival of grouper was highest in oyster-fish polyculture while oyster’s survival was highest in the IMTA system. Results indicate that the combination of Crassostrea iredalei and Gracilaria balinae can effectively reduce ammonia and phosphate from grouper excretion even though the growth rates of the test organisms were not enhanced. Based on the results of this experiment an IMTA system of these three organisms is feasible. To increase growth and survival, it is recommended that the experimental design be refined.