Phosphate Concentration from the Water around the Floating Cage Fish Culture Area and from the Area with No Cage, in the DAM Site of the Koto Panjang Reservoir

Abstract

In floating cage fish culture activities, degradation of feed remain and fish feces will
increase the Phosphate content in the surrounding area. A research aims to understand the
Phosphate concentration in the water from the cage area and from the area that has no cage has
been done from July - November 2014. There were 3 stations, namely 200 m upstream nof the
cage area (S1), in the cage area (S2) and 200 m downstream of the cage area (S3). Samplings
were conducted in the DAM site 4 times, once/2 weeks. In each station, water samples were
collected from 3 different depth, surface; 2 secchi and 4 secchi depths. Parameters measured
were pH, Phosphate concentration, Dissolved Oxygen, transparancy, temperature and depth.
Results shown that the concentration of Phosphate in the S1was 0.03 mg/L – 0.13 mg/L; in the
S2 was 0.13 mg/L – 0.35 mg/L; and in the S3 was 0.07 mg/L – 0.22 mg/L. The highest
concentration of the Phosphate was in S2, while the lowest was in the upstream (S1). Phosphate
concentration indicates that the DAM site area of the Koto Panjang can be classified as
eutrophic, especially in the area around the cage. Other water quality parameter measured were
temperature: 30.6oC – 31oC; transparancy 1.98 m – 2.55 m; depth 27 m – 40 m; pH 5 and free
CO2: 4.66 mg/L- 15.31 mg/L. the values of water quality parameters indicate that the water
quality in the DAM site of the Koto Panjang is good and might be able to support the life of
aquatic organisms in thet area.
Keywords: phosphate, cage fish culture,Koto Panjang Dam