ILMU KELAUTAN: Indonesian Journal of Marine Sciences March 2021 Vol 26(1):37-44 e-ISSN 2406-7598 *) Corresponding author © Ilmu Kelautan, UNDIP ijms.undip.ac.id DOI: 10.14710/ik.ijms.26.1.37-44 Received: 24-11-2020 Accepted: 01-02-2021 Phytoplankton community structure and it’s relationships with water quality in Bangka Island, Indonesia Muh Yusuf 1* , Robin Robin 2 , Wahyu Adi 3 , Mu’alimah Hudatwi 4 , Widianingsih 5 , Retno Hartati 5 , Robertus Triaji Mahendrajaya 5 , Cristiana Manullang 6 1 Department of Oceanography, Faculty of Fisheries and Marine Sciences, Diponegoro University Jl. Prof. Sudarto, SH, Tembalang, Semarang, Jawa Tengah, 50275 Indonesia 2 Department of Aquaculture, Faculty of Agriculture, Fisheries and Biology, University of Bangka Belitung Balunijuk Campus Centre, Merawang, Bangka, Bangka Belitung 33172, Indonesia 3 Department of Water Resource Management, Faculty of Agriculture Fisheries and Biology, University of Bangka Belitung Balunijuk Campus Centre, Merawang, Bangka, Bangka Belitung 33172, Indonesia 4 Department of Marine Science, Faculty of Agriculture, Fisheries and Biology, University of Bangka Belitung Balunijuk Campus Centre, Merawang, Bangka, Bangka Belitung 33172, Indonesia 5 Department of Marine Science, Faculty of Fisheries and Marine Sciences, Diponegoro University Jl. Prof. Sudarto, SH, Tembalang, Semarang, Jawa Tengah, 50275 Indonesia 6 Graduate School of Engineering and Science, University of the Ryukyus Nishihara, Okinawa, Japan Email: yusuff.undip@gmail.com Abstract Phytoplankton plays an important role in primary productivity in marine environment. Various environmental changes in coastal area will impact the water quality and their phytoplankton compositions. The purpose of this study is to examine the abundance of phytoplankton from two different sites, i.e Tanah Merah (close to mining site) and Semujur Island (away from mining site) in Bangka Island. Phytoplankton and water sample were collected on June- August 2018. Water quality was measured using water quality checker, whereas the phytoplankton was identified under the microscope with a magnification of 100x. Non-parametric Kruskal test and T-test analysis was performed to determine the abundance, diversity, uniform, and dominance of phytoplankton between Sites, respectively. Statistical analyses showed the abundance of phytoplankton at Semujur Island was significantly higher than that at Tanah Merah (p = 0.003). In additions the diversity, uniform, and dominance were also significantly different between sites (all p <0.05). In Semujur Island, Diatoms (Thalassiothrix, Chaetoceros and Thalassionema) were more dominants than the Dinophyceae group. However, in Tanah Merah, the genera Ceratium belong to class Dinophyceae was more dominant than the class Bacillariophyceae. These results performed that the phytoplankton in Tanah Merah and Semujur Island was affected by environment, in this case the mining area. The water quality in Semujur Island (non-mining Area) might have good quality than in Tanah Merah (mining area). The average value of turbidity and Total Suspended Solid in Tanah Merah Waters causes low abundance of phytoplankton. It can be concluded that tin mining can disrupt the abundance and composition of phytoplankton as a primary producer of waters. Keywords: Tin Mining, Phytoplankton, Tanah Merah, Semujur Island, Bangka, Indonesia Introduction Phytoplankton compositions are determined by environmental parameters and their physiological characteristics. Compositions and abundances of phytoplankton will change as a result to environmental variance conditions both physical, chemical, and biological (Reynolds et al., 2002). Several factors are controlling the phytoplankton distributions, such as marine physical process and nutrient inputs. Moreover, the change of water quality impacts of marine ecosystem included the composition of phytoplankton. (Nguyen and Nhien, 2020). The research on phytoplankton community response to these changes is useful to analize the hydrological variations in coastal waters (Troccoli et al., 2004). The water quality assessment by using biological material approach, such phytoplankton, will reflect changes caused by a decrease in quality a water.