Biological pollution potential in the water of Bintan-Riau Islands Province, Indonesia: First appearance of harmful algal bloom species Agung Dhamar Syakti a,b,⇑ , Fadhliyah Idris a , Chandra Joei Koenawan a , Rayandra Asyhar c , Tri Apriadi d a Marine Sciences Department, Marine Sciences and Fisheries Faculty – Raja Ali Haji Maritime University, Jl. Politeknik Senggarang-Tanjungpinang, Riau Islands Province 29100, Indonesia b Center for Maritime Biosciences Studies – Institute for Sciences and Community Service, Jenderal Soedirman University, Kampus Karangwangkal, Jl. dr. Suparno, Purwokerto 53123, Indonesia c Chemistry Department, Faculty of Education and Teacher Training – Jambi University, Jl. Raya Jambi – Muara Bulian KM. 15 Mendalo Indah, Muaro Jambi, Jambi, Indonesia d Aquatic Resources Management Department, Marine Sciences and Fisheries Faculty – Raja Ali Haji Maritime University, Jl. Politeknik Senggarang-Tanjungpinang, Riau Islands Province 29100, Indonesia article info Article history: Received 25 October 2018 Revised 18 April 2019 Accepted 24 April 2019 Available online 28 April 2019 Keywords: Bintan Island Phytoplankton HABs Ceratium Bacillariophyta Eutrophication abstract The increased number of human population in coastal areas can be the common dominator of an event of harmful algal blooms (HABs), which might be of a negative impact on human activities. Generally, HABs occur due to the dynamics of some phytoplankton species. The objective of this study was to inventory the phytoplankton distribution in the water of Bintan-Riau Island in Indonesia. In the perspective of the pollution biology mitigation, phytoplankton samples were collected from 4 to 5 composited sub-samples of the seven sites around the Bintan water (Dompak, Kijang, Kampung Baru, Lobam, Trikora, Tanjung Unggat and Senggiling). The investigation revealed the presence of 41 phytoplankton taxa. Bacillariophyta was the dominant group of phytoplankton in the coastal waters of the Bintan Island. The highest abundance of phytoplankton is found in the Dompak and Senggiling waters with the number of phytoplankton per mL reached 1.846.667 and 2.050.667 cells/mL, respectively. Both stations had the highest number of phytoplankton species (26 species) compared to other stations. The harmful phyto- plankton group found was dinophyceae (genus Ceratium), which was observed in almost all the coastal waters of Bintan Island. The highest abundance of dinophyceae was in the waters of Kampung Baru, Lagoi. In this study, HABs proliferation was associated with nitrate concentration, which recorded high values in all the observation sites. An eutrophication study is needed to understand the broader complex- ity of nutrient effects governing the occurrence of HABs in the coastal areas, which can help in the mit- igation of problems caused by HABs, particularly in Dompak and Senggiling stations. Ó 2019 National Institute of Oceanography and Fisheries. Hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Introduction Bintan Island is one of the main islands in the Riau Islands Pro- vince. Three administrative centers are located on Bintan Island, namely the capital of Riau Islands Province, Bintan Regency, and Tanjung Pinang City. The lengths of the coast lines of Bintan Regency and Tanjung Pinang City are 982.41 km and 158.25 km, respectively. Domestic, industrial, mining, touristic, and aquacul- ture activities around Bintan Island are thought to contribute to the low water quality and eutrophication. Eutrophication is a nutri- ent enrichment process (direct or through decomposition), which has an impact on the recurrent occurrence of many events, such as the increasing of phytoplankton production and the decreasing of water quality. This eutrophication process will trigger an increase in algal blooms and the incidence of harmful algal blooms (HABs). The phenomenon of algal blooms in Lagoi (North Bintan) water in the midst of February 2018 indicates the potential dangers of the population of phytoplankton in the Bintan waters. Based on local observations, it is known that the type of phytoplankton that appears in the beach of Banyan Tree Lagoi is Trichodesmium sp. from the cyanophyta group. On the other hand, Paralia sp. from the Bacillariophyta is found in the Bintan Lagoon. Generally, phytoplankton blooms arise due to the imbalance of N and P nutrients in the waters (Xu et al., 2015; Abboud-Abi Saab and Hassoun, 2017). The problem of the enrichment of nutrients in https://doi.org/10.1016/j.ejar.2019.04.002 1687-4285/Ó 2019 National Institute of Oceanography and Fisheries. Hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer review under responsibility of National Institute of Oceanography and Fisheries. ⇑ Corresponding author at: Marine Sciences Department, Marine Sciences and Fisheries Faculty – Raja Ali Haji Maritime University, Jl. Politeknik Senggarang-Tanjungpinang, Riau Islands Province 29100, Indonesia. E-mail address: agungsyakti@chemist.com (A.D. Syakti). Egyptian Journal of Aquatic Research 45 (2019) 117–122 Contents lists available at ScienceDirect Egyptian Journal of Aquatic Research journal homepage: www.sciencedirect.com/locate/ejar