1 Concentration of Chlorophyll-a as the Determinant of Trophic Status in the Samsam Swamp, Kandis Sub District, Siak District, Riau Province By Silvia Karmila 1 , Clemens Sihotang 2 , Tengku Dahril 2 Email: silvia.karmila93@gmail.com ABSTRACT Samsam Swamp is a lowland swamp that receives water from the Samsam River during the rainy season. To understand the trophic status of Samsam Swamp, a present study based on the concentration of chlorophyll-a was conducted in March-April 2016. The method used was a survey method. There were four sampling stations namely Station 1, Station 2, Station 3 and Stasion 4. Samplings were conducted 3 times, once a week. Results shown that concentration of chlorophyll-a was 4.05 – 7.69 μg/L; temperature 28 – 33⁰ C, transparency 28 – 46.9 cm, water pH 4 – 5, orthophosphate 0.37 – 0.65 mg/L, nitrate 0.33 – 0.63 mg/L, dissolved oxygen 3.69 – 4.93 mg/L, free carbon dioxide 4.00 – 11.99 mg/L and depth 39 – 170 cm. Based on the concentration of chlorophyll-a, Rawa Samsam is classified as mesotrophic waters. Keywords: Lowland Swamp, Samsam Swamp, Chlorophyll-a, Trophic Status 1) Student of the Fisheries and Marine Sciences Faculty, Riau University 2) Lectures of the Fisheries and Marine Sciences Faculty, Riau University PENDAHULUAN Rawa Samsam merupakan salah satu perairan rawa di Provinsi Riau yang sebagian areanya telah mengalami alih fungsi menjadi lahan perkebunan kelapa sawit dan pemukiman penduduk. Rawa Samsam adalah perairan rawa gambut yang terletak di antara perbatasan Kabupaten Siak dan Bengkalis dan merupakan jenis perairan rawa lebak yang terbentuk dari banjiran Sungai Samsam, dimana sumber airnya berasal dari limpasan Sungai Samsam saat musim hujan. Perairan rawa gambut alami pada umumnya memiliki kelimpahan fitoplankton yang relatif kecil disebabkan oleh konsentrasi unsur hara yang rendah (Nathania dalam Sihaloho, 2016). Akan tetapi kelimpahan fitoplankton di suatu perairan tidak selalu berkorelasi secara nyata dengan kandungan klorofil-a, karena proporsi klorofil-a dapat berbeda pada setiap jenis fitoplankton yang berbeda (Aryawati