Bacteria population on Eucheuma denticulatum (Rhodophyta) thallus infected by ice-ice disease cultivated on horizontal net cage

Ice-ice is one of the seaweed diseases. The population of bacteria in seaweed affected by ice-ice is estimated to be quite high. This research aims to identify the amount of bacteria population on seaweed (E. denticulatum) infected by ice-ice disease. This research used Complete Random Design with three treatments and three repetitions. Bacteria population analysis used a media of Tryctic Soy Agar (TSA) and solution of Butterfield's Phosphate Buffered (BFP) with agar spread technique. The sample s were part of thallus that had ice-ice disease, compared to healthy thallus which was close to ice-ice and healthy thallus sample which was far from ice-ice, each sample measured 25 g in weight. The results show that highest average bacteria population on thallus with ice-ice (TS) was 8.73 x 108 CFU mL-1 (log: 7.94) and the lowest on healthy thallus far from ice-ice (TJ) was 1.03 x 107 CFU mL-1 (log: 7.01). Water quality parameter measurement results during the research showed water transparency of 6.28 m, temperature 29°C, depth 7.32 m, current velocity 11.56 m, salinity 33 ppt, dissolved oxygen (DO) 7.8 mg L-1, nitrate 0.0104 mg L-1 and phosphate 0.0042 mg L-1. There was no significant correlation evidenced between environmental conditions and ice-ice disease.