Ecology, Environment and Conservation Paper

TROPHIC STATUS AND LOAD CAPACITY OF WATER POLLUTION WASTE FISH CULTURE WITH FLOATING NET CAGES IN MANINJAU LAKE, INDONESIA

Hafrijal Syandri, Azrita and Niagara

Abstract

Maninjau Lake has strategic values Hydroelectric power plant, tourism, capture fisheries and floating net cages farming. The function of the lakeis now nolonger in accordance with its designation, because there has been a degradation of water quality, nutrient enrichment and exceed the carrying capacity. Research on the status of the waters of ManinjauLake has been conducted on April 2014, August 2014 and January 2015 in order to determine status of water quality, status of trophic and water pollution loading capacity. The results showed the elevation 462.82 meters above sea level lake surface area is 9,737.50 ha the water quality among others pH ranged from 6.63 to 6.80, total dissolved solids ranged from 12.44±0.13 to 22.84±1.48 mg/L and water transparency is very low ranged from 1.40±0.10 to 2.10±0.36m. Total phosphorus (TP) ranged from 0.47±0.10 to 0.65±0.15mg/L, total nitrogen (TN) in the range from 1.64±0.05 to 2.06±0.16 mg/ L and chlorophyll-a ranged from 0.74 ± 0.012 to 1.295 ± 0.0253 mg/m3. Trophic status index values 78.62±1.15, based on the value of Maninjau Lake classified status heavy eutrophic. The capacity of the waters of Maninjau Lake is 15,432.90 tons fish/year or equivalent to 8,230 units offloating net cages. This means it is an over production of 8,747.1 tons, equivalent to 5,831 units of floating net cages.