Plankton merupakan komponen utama dalam rantai makanan ekosistem perairan yang terdiri dari fitoplankton dan zooplankton. Meningkatnya aktivitas pada daerah pesisir akan mempengaruhi perairan dan berdampak pada produktivitas tambak tradisional. Tujuan penelitian untuk mengetahui kelimpahan, keanekaragaman, dan dominansi fitoplankton dan zooplankton pada perairan tambak tradisional Kelurahan Pamusian Kota Tarakan. Penelitian dilaksanakan pada bulan Maret sampai dengan April 2021. Penelitian menggunaan metode deskriptif kuantitatif dengan penentuan lokasi menggunakan teknik purpossive sampling. Identifikasi plankton dilakukan di Laboratorium Nutrisi dan Pakan Ikan Fakultas Perikanan dan Ilmu Kelautan Universitas Borneo Tarakan. Hasil penelitian ditemukan Fitoplankton berjumlah 3 kelas yaitu Bacillariophyceae, Cynophyceae, dan Dinophyceae. Zooplankton berjumlah 5 kelas yaitu Crustacea, Rotifera, Polychaeta, Tunicata, dan Pisces. Kelimpahan zooplankton yaitu berkisar antara 0,9-15,1 ind/L, kelimpahan Fitoplankton yaitu berkisar antara 1,33–6,69 ind/L, hal ini menunjukkan bahwa kelimpahan zooplankton tergolong rendah (oligotrofik). Keanekaragaman Zooplakton berkisar antara 0,91-1,60, sedangkan keanekaragaman Fitoplankton berkisar antara 1,96-3,38. Keanekaragaman termasuk dalam komunitas rendah, dan indeks dominansi zooplaknton yang didapatkan berkisar antara 0,43-0,52 indeks dominansi pada pagi hari berkisar antara 0,12-0,37 sedangkan indeks dominansi Fitoplankton berkisar antara 0,07-1,23. kondisi komunitas tersebut terdapat jenis yang mendominasi yaitu kelas crustacea jenis Bacillariophyceae.
Kata Kunci: Kota Tarakan, Perairan Tambak Tradisional, Plankton

Plankton is the main component in the food chain of aquatic ecosystems consisting of phytoplankton and zooplankton. Increased activity in coastal will affect the waters and have an in impact on the productivity of traditional ponds. The purpose of the study was to determine the abundance, diversity, and dominance of phytoplankton and zooplankton in traditional waters, Pamusian village, Tarakan City. The study was carried out from March to April 2021. Purposive samling was utilized in the study to identify the lacation using a quantitative descriptives method. The indentification of plakton was carried out at the laboratory of nutrition and fish feed, Faculty of Fisheries and Marine Sciences, University of Borneo Tarakan. The results of the study showed that there were 3 classes of phytoplankton, namely Bacillariophyceace, and Cynophyceae, and Dinophyceae. there were 5 classes of zooplankton, namely Crustacea, rotifera, polychaeta, tunicate, and pisces. The abudance of zooplankton ranged from 0.9-15.1 ind/, the abundance of phytoplankton ranged from 1.33-6.69 ind/L, this indicates that the abundance of zooplankton is low (oligotrophic). The diversity of zooplankton ranged from 0.91 to 1.60, while the diversity of phytoplankton ranged from 1.96 to 3.38. diversity was included in the low community, and the dominance index of zooplankton obtained ranged from 0.43-0.52, the dominance the index in the morning ranged from 0.12-0.37 while the dominance index oh phytoplankton ranged from 0.07-1.23. the condition of the community was that there were species that dominate, namely the crustacean class, Bacillariophyceae. Keywords: Tarakan City, Traditional Poun, Plankton