KAJIAN KEMAMPUAN RUMPAI LAUT ULVA INTESTINALIS SEBAGAI PENAPIS AIR LAUT SEMULA JADI BAGI PENGKULTURAN SECARA INTENSIF ROTIFER BRACHIONUS PLICATILIS

The ability of Ulva intestinalis as a biofilter in the intensive culture of rotifer Brachionus plicatilis was evaluated. 20 g wet weight of U. intestinalis was added into a 40 liters beaker containing 10 liters sea water of the cultured rotifer with quality index 0.36 ± 0.28 mg/L of NH3–N, 0.069 ± 0.025 mg/L of NO2––N, 0.90 ± 0.77 mg/L of NO3––N and 0.993 ± 0.0058 mg/L of PO43– and the alkalinity reading 114 ± 0.1 mg/L, pH 7.23 ± 0.08, temperature 26.3 ± 0.1OC and salinity was 30 ± 0.1 psu. The result of the following day of treatment with U. intestinalis, the water quality index changed to 0.001 mg/L of NH3–N, 0.090 ± 0.014 mg/L of NO2––N, 0.70 ± 0.60 mg/L of NO3––N and 0.89 ± 0.03 mg/L of PO43– while the alkalinity was 114 ± 0.1 mg/L, pH 7.45 ± 0.05, temperature 26.0 ± 0.10OC and the salinity was 30.0 ± 0.1 psu. The biofiltration capacity of U. intestinalis was confirmed by significantly reduced concentration of the NH3–N and 10% of PO43– compared to control only 2% over one day treatment. However from day two onwards the readings were conflicting from the first day readings. These findings were probably because U. intestinalis live in intertidal zone and flushing area therefore the use of U. intestinalis as a biofilter by continuous immersion in cultured water is unnatural. Therefore using U. intestinalis as a biofilter should be used not more than 24 hours.