Karakteristik dan klasifikasi trofik di Danau Matano dan Danau Towuti Sulawesi Selatan

A lot of research showed that Lake Matano and Towuti have high endemicity organisms but low productivity. Low productivity in both lakes, probably, occurs because of lack of nutrient. Therefore, the transparence of these lakes is still showing clear water. In relation to lake management, classification of Tropic Status is important thing to be determined. Hence, we try to conduct a study on the determination of the trophic status of Lake Matano and Towuti. Classification of these lakes according Trophic status was conducted by observing Total Nitrogen (TN), Total Phosphorus (TP), Secchi depth, and High precision of Seabird CTD profile for chlorophyll-a (fluorescence), and other Physicochemical parameter such as Dissolved Oxygen, temperature, conductivity, Photosynthetically Active Radiation (PAR), and % Light Transmission. The investigation was conducted on October 2013 at the middle of the lakes surface water. Lake Matano still have the aerobic zone through depth of 95-100m whereas Lake Towuti through depth of 130-135m. The concentration of nutrient is very low (The concentration of TP is <0.005 mg/L). The Secchi depth is still showing until 25m for Lake Matano and 21,5m for Lake Towuti. The euphotic zone (PAR is 1% of its surface value) is 87m for matano and 75m for Towuti, whereas abundance of Chlorophyl a is <2µg/m 3 for both lakes. Classification of trophic status of both lakes was still oligotrophic that characterized by single parameter such as nutrient, the abundance of chlorophyll-a and Secchi depth. Classification of Status trophic based on Carlson’s composite indice (Tropic State Index, TSI), showed that The Trophic Status of Lake Matano and Towuti was still classical oligotrofic (Ultraoligotrophic).