Simarmata, Asmika HSiagian, Madju2014-01-302014-01-302014-01-30wahyu sari yenihttps://repository.unri.ac.id/xmlui/handle/123456789/5432A research on vertical profile of Phosphate and Chlorophyl-a around floating cage area in the Bandar Khayangan Reservoir, Riau Province has been conducted on August 2011. This research aims to understand the vertical profile of phosphate and chlorophyll-a and trophic status of the water. Water samples were collected from 3 stations, namely station 1 ( in the upstream of the floating cage area), station 2 (in the floating cage area) and station 3 (downstream of the floating cage area). There were 2 sampling sites in each station, in the surface and in 2.5 secchi depth. Sampling was done three times, once a week. Results shown that Phosphate content in the surface was lower than that of the 2.5 secchi depth. In contrast, the chlorophyl-a in the surface was higher than that of the 2.5 secchi depth. Phosphate content in the surface was ranged from 0.09-0.15 mg/l, in 2.5 secchi depth was 0.09- 0.28 mg/l. Chlorophyll-a in the surface was 16.04-31.55 mg/l and in 2.5 secchi depth was 12.54-21.84 mg/l. Transparency was 53.0-68.3 cm, depth was 1.8-3.51 m, water temperature was 29.6-30.3oC, pH 5.5, dissolved oxygen was 4.5-6.0 mg/l and CO2 was 4.7-8.0 mg/l. Based on data obtained, it can be concluded that the water of the Bandar Khayangan Reservoir was very productive and able to support aquatic organisms living in that dam.enBandar Khayangan Reservoirfloating cagephosphate and chlorophyll-aUR-Proceedings