Study on phytoplankton diversity of Batang Toru River and its surrounding, North Sumatra, Indonesia

Abstract

Batang Toru River which is located in South Tapanuli, North Sumatra, is quite widely used for various purposes, i.e. domestic uses, fisheries and tourism activities. Phytoplankton study at 13-14 stations which are distributed from the area near the upstream to the estuary of Batang Toru River was conducted for 3 months i.e. April, July, and October 2019. In each sampling station, water quality environment i.e. temperature, transparency, turbidity, pH and DO were also observed. Data analysis including phytoplankton abundance, diversity index (H’), evenness index (E), and dominance index (C) of the organism. Generally, water quality in all stations were still in accordance with the quality standards for aquatic life. During the study period, a total of five classes of phytoplankton were recorded, namely Bacillariophyceae (represented by 26 genera), Chlorophyceae (15 genera), Cyanophyceae (7 genera), Dinophyceae (1 genus), and Eiglenophyceae (2 genera). Diversity, Evenness and Dominance Indices varied with range of 0.377-1.847, 0.503-1.000 and 0.187-0.781, respectively. Based on the status of the phytoplankton community structure, the ecological status of the Batang Toru River is classified as moderate.