Microplastics are particles that have a size of 5 mm, where its existence might be able to contaminate the biota in the aquatic environment. This research was conducted in the coastal waters of Bengkalis Island in December 2020 with the aim to determine the types and analyze its abundance of microplastics in each area with different sources of anthropogenic input in the north and south Bengkalis Island. Sampling of sea water for microplastic analysis was done using plankton net (diameter 30 cm and mesh size 30 μm) from six sampling stations. Thirty six individual samples of Duri (Arius maculatus), Lomek (Harpodon nehereus), and Biang (Setipinna breviceps) fish were obtained with the help of local fishermen in each sampling location. The results showed that the types of microplastics found in seawater samples are fiber and film with average abundance ranges between 9.58 particles/m3 - 40.42 particles/m3. The highest abundance was found in station 6 (60.83 ± 8.61 particles/m3 and 20.00 ± 8.94 particles/m3) for fiber and film, whilst the lowest abundance was found in station 3 (12.50 ± 5.24 particles/m3 and 6.67 ± 6.06 particles/m3) for fiber and film, respectively. The average abundance of microplastics found in the digestive tract of fish was 62.96 particles/ind. which consisted of fiber, film and fragment. The highest microplastic abundance was found in Duri fish (72.22 particles/ind.), whilst the lowest was found in Lomek fish (55.56 particles/ind.). Although the abundance of microplastic in coastal waters of north Bengkalis were higher than that in the south of Bengkalis Island, statistically they were significantly different. This was presumably due to differences in oceanographic influences such as current and waves between the two water masses as well as anthropogenic activities in both areas that can affect the spread and distribution of microplastics.Keywords: plastic waste, Bengkalis waters, demersal fish, pelagic fishABSTRAKMikroplastik adalah partikel yang memiliki ukuran 5 mm, di mana keberadaannya dapat mencemari biota di lingkungan akuatik. Penelitian ini dilakukan di perairan pantai Pulau Bengkalis pada Desember 2020 dengan tujuan untuk menentukan jenis dan menganalisis kelimpahan mikroplastik di setiap wilayah dengan berbagai sumber input antropogenik bagian utara dan selatan Pulau Bengkalis. Pengambilan sampel air laut untuk analisis mikroplastik dilakukan menggunakan plankton net (diameter 30 cm dan ukuran jala 30 μm) dari enam stasiun pengambilan sampel. Tiga puluh enam sampel individu ikan Duri (Arius maculatus), Lomek (Harpodon nehereus), dan Biang (Setipinna breviceps) diperoleh dengan bantuan nelayan lokal di setiap lokasi pengambilan sampel. Hasil penelitian menunjukkan bahwa jenis mikroplastik yang ditemukan dalam sampel air laut adalah fiber dan film dengan kisaran kelimpahan rata-rata antara 9,58 partikel/m3 - 40,42 partikel / m3. Kelimpahan tertinggi ditemukan di stasiun 6 (60,83 ± 8,61 partikel / m3 dan 20,00 ± 8,94 partikel / m3) untuk fiber dan film, sedangkan kelimpahan terendah ditemukan di stasiun 3 (12,50 ± 5,24 partikel / m3 dan 6,67 ± 6,06 partikel / m3) untuk fiber dan film. Kelimpahan rata-rata mikroplastik yang ditemukan dalam saluran pencernaan ikan adalah 62,96 partikel / ind. yang terdiri dari fiber, film dan fragmen. Kelimpahan mikroplastik tertinggi ditemukan pada ikan Duri (72,22 partikel / ind.), sedangkan yang terendah ditemukan pada ikan Lomek (55,56 partikel / ind.). Meskipun kelimpahan mikroplastik di perairan pantai Bengkalis utara lebih tinggi daripada di selatan Pulau Bengkalis, secara statistik mereka berbeda nyata. Ini mungkin karena perbedaan dalam pengaruh oseanografi seperti arus dan gelombang antara dua massa air serta aktivitas antropogenik di kedua daerah yang dapat mempengaruhi penyebaran dan distribusi plastik mikro.Kata kunci: sampah plastik, perairan Bengkalis, ikan demersal, ikan pelagis
Plankton community in the western waters of North-Sumatera during the onset monsoon of Asian winter