Produktivitas Primer Fitoplankton Dan Hubungannya Dengan Faktor Fisik-Kimia Air Di Perairan Parapat, Danau Toba

Abstract

The aimed of this research were to investigated the value of primary productivity in Lake Toba as result of activity of phytoplankton photosynthesis and its relation with the value of physic and chemical factors of water. This research has been done during March - April 2008 at the 4 sampling locations around Parapat, Toba Lake. 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 are suspended at the depth from which the samples were obtained. The other analysis would be conducted to measurement the physic and chemical factors of water, such as the temperature, pH, Dissolved Oxygen, Secchi Disk visibility, BOD5, NO3, PO4, and the density of plankton. The mean value of primary productivity range from 387,873 to 825,739 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). 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 0,034 which is smaller than 0,05). Activity of settlement/domestic and hotels (2nd and 3rdlocations) giving contribution to increase the nutrient concentration of water, causing optimal growth of phytoplankton.