Abstract:
The study to determine the types of phytoplankton around Segati River, Langgam District. The research was conducted in Juni-September 2012 in the Segati River, Langgam District, Pelalawan Regency, Riau. Phytoplankton types found during the study in the Segati River, Langgam District consisted of five classes and (17 species) namely the class Cyanophyceae (7 species), class Cryptophyceae (1 species), class Chlorophyceae (6 species), class Xanthopyceae (1 species) and class Bacillariophyceae (2 species). Abundance values of phytoplankton in the Segati River Langgam District, ranging from 625 cel/l – 1550 cell/l, diversity index (H’) around 1,0 – 3,0. Dominancy index (C) around 0.110 – 0.296 and equitability index (E) around 0.684 – 0.957. Water quality parameter in the Segati River, namely : temperature 29 0C – 31 0C, brightness 35 cm – 39 cm, flow velocity 0,10 m/dtk – 0,15 m/dtk, depth 4 – 6 m, the degree og acidity (pH) 5 – 6, dissolved oxygen (DO) 7,16 mg/l – 7,34 mg/l, carbon dioxide-free (CO2 free) 6,99 mg/l - 7,29 mg/l, Nitrate 0,030 mg/l – 0,047 mg/l and phosphate 0,004 mg/l – 0,007 mg/l. Based on the nitrate and phosphate, Segati River classified oligotrofik waters.
