Diversity of Planktonik Diatom at Bengkalis Waters, Riau Province

Abstract

This research was carried out in August to September 2019 at Bengkalis Waters, Riau Province. This study goals to describe the water quality statues and to determine the species composition, abundance and biological index of planktonic diatom in the Bengkalis waters. Survey method was applied in this research which are 5 stations established, with 3 sampling points in each station. The stations were determined purposively based on antrophogenic activities conducted in that area. Diatom samples were filtered from surface water as much as 100 liters by using plankton net number 25, and the samples were then observed using an Olympus CX 21 microscope (magnification 10 x 10 and 10 x 40) and were identified. The value of water quality at each station indicates that the water is in normal range and it may support the growth of diatoms. There were 20 spesies of planktonic diatoms recorded in the Bengkalis waters. There were 2 species, namely Coscinodiscus sp. and Navicula sp. that were found in each station. Meanwhile, the abundance of plankatonic diatoms ranged from 23,041.80 to 286,693.18 ind/l. The average of biological indices values are as follows: diversity index 1.39-2.32, dominance index 0.24 to 0,48 ind / l, and the uniformity index 0.55 to 0.87 ind / l. The biological indices values indicated that the Bengkalis Waters can be categorized as moderate polluted water and there is no dominant species.