JENIS DAN KELIMPAHAN FITOPLANKTON DI DANAU TOBA DESA HUTA HOTANG KECAMATAN ONAN RUNGGU KABUPATEN SAMOSIR PROVINSI SUMATERA UTARA

Abstract

This research has been conducted in July 2012 in Lake Toba. The research used survey method. There were 3 station, Station 1: The litoral zone of resident activities such as washing, gardening, farming, tourism, and chart for fishing, Station 2: located in the middle of Lake Toba, Station 3: Outlet of Lotung river, around 500 meters from the station 1. Samplings were conducted 3 times, once/week. This research aim to know abundance of phytoplankton in Lake Toba. The results showed 47 kinds of phytoplankton that classified into 5 classes, there were :Chlorophyceae (15species), Cyanophyceae (6species), Bacillariophyceae (12species), Chrysophyceae (4species), and Xanthophyceae (10species). The average of phytoplankton abundance around 77.076-116.993 cel/l, Diversity index (H') of phytoplankton around 2,845-2,891 and Domination index (C) around 0,052-0,065. Whereas water quality parameter such as temperature around 28,3-30oC, Transparency around 433,3-650 cm, Depth around 20-70 m, pH 6, Dissolved Oxygen around 4,3-6,3 mg/l, Free carbondioxide around 3,73-5,03 mg/l, Nitrate around 0.01-0.02 mg/l, Phosphate around 0,023 mg/l. Based on abundance of phytoplankton, concluded the stations of research in lake Toba mesotrophic water