Hubungan Nilai Produktifitas Primer dengan Konsentrasi Klorofil a dan Faktor Fisik Kimia Air di Danau Toba Parapat, Kabupaten Simalungun

Abstract

The aim of research was to investigate the value of primary productivity in Lake Toba as result of activity photosynthesis phytoplankton and its relation with the value of chlorophyll, physic and chemical factors of water. This research has been done during March - April 2008 at 4 sampling locations around Parapat, Lake Toba. The sampling location determined depends on various activities in each sampling location. Primary Production was measured by the Oxygen Method were two bottles with a given concentration of phytoplankton (small aquatic organisms) are suspended at the depth from which the samples were obtained. The "dark" bottle is wrapped in aluminum foil, to exclude light; the "light" bottle is clear. A quantity of oxygen proportional to the total organic matter fixed (gross production) is produced by photosynthesis in the light bottle. At the same time, some of the oxygen is being utilized in respiration. The other analysis would be conducted to measurement the chlorophyll, physic and chemical factors of water, such as the temperature, pH, Dissolved Oxygen, Secchi Disk visibility, BOD5, NO3, PO4. The mean value of primary productivity range from 387,873 to 825,793 mg C/m3/dy, with the lowest value obtained at location 4 and highest value at location 2. The lowest value of primary productivity equal to 187,68 mg C/m3 /dy obtained at surface (location 4). The highest value of chlorophyl equal to 95,213 mg/m3 at location 2 and the lowest value of chlorohyl equal to 14,426 mg/m3 at location 3. According to statistical test obtained that there no significance difference of value of primary productivity which is compared between locations, since the value of primary productivity at surface was different compared with the value obtained at deepness 2,5 m (significance value equal to 0,014 which is smaller than 0,05).