The Potential of Carbon and Chlorophyll Concentration on Phytoplankton in Lakes at Campus Universitas Indonesia, Depok Sumiriyati, Anggari Kirana Dewi Abstract— Lakes has potential as a carbon sink in the waters. Primary productivity is the rate of formation of organism compound from the energy rich inorganic compounds. This study is about the level of carbon uptake and chlorophyll content on phytoplankton, is aims to analyze the level of carbon uptake study was conducted in six lakes Campus University of Indonesia Depok, namely Kenanga, Agathis, Mahoni, Puspa, Ulin and Salam. Sampling was conducted in September-October 2015. The dark-light bottle method used to measure the primary productivity in the waters. Bottle of darks and light was placed at a dept of 0 cm, 10 cm, 30 cm, 50 cm and 70 cm. Sampling of phytoplankton was conducted using a plankton net. Measurement of chlorophyll-a, chlorophyll-b and chlorophyll-c using a spectrophotometer with a wavelength of 750, 664, 647 and 630 nm. The rate of carbon uptake in six lakes Campus University of Indonesia Depok it has potential to absorb carbon average between 0.442--0.879 mgC/m 3 /hour. The content of chlorophyll-a, chlorophyll-b and chlorophyll-c, largest average in a row is obtained in Agathis Lake is 0.135 mg/l, Kenanga Lake is 0.095 mg/l and Kenanga Lake is 0.116 mg/l. The smallest average in a row is Kenanga lake is 0.012 mg/l, Puspa 0.016 lake is mg/l and Agathis lake 0.003 mg/l. The results of the identification of phytoplankton samples obtained in class Chlorophyta, Cyanobacteria and Bacillariophyta (Diatom) Keywords--- Carbon, phytoplankton, primary productivity, chlorophyll, University of Indonesia Depok. I. INTRODUCTION Phytoplankton are group of plankton that has pigment of chlorophyll. Therefore phytoplankton can do the process of photosynthesis to form organic substances from inorganic substances. The ability to perform photosynthesis cause phytoplankton has a major role as producers in aquatic ecosystems [5]. Phytoplankton can generally be divided into two groups based on the shape of the cell, namely unicellular with a size of about 2 μm and multicellular or shaped like a thread (filament) with a length of up to 8 μm. Freshwater phytoplankton are dominated by Cyanophyta (Cyanobacteria), Chlorophyta, Bacillariophyta (diatoms) and Euglenophyta [5]. Department of Biology, Faculty of Mathemathics and Natural Sciences, University of Indonesia, Depok 16424, Indonesia Chlorophyll is a pigment in the chloroplasts utilized by phytoplankton in photosynthesis process which is found in all autotrophic organisms [4]. Chlorophyll-a is a pigment which could absorb and distribute energy directly from sunlight during photosynthesis, while other pigments such as chlorophyll-b and chlorophyll-c could only distribute the light energy absorbed by chlorophyll-a. Chlorophyll-a is able to absorb sunlight at wavelengths less than 460 nm (blue) and 630-670 nm (red) [2]. Phytoplankton plays an important role as a producer of carbon through photosynthesis. In general, the primary productivity of water is controlled by environmental conditions, such as solar radiation, nutrient availability, and the ability of photosynthetic phytoplankton species. The rate of primary productivity will be high if the environmental factors are suitable or optimal. Measurements of primary productivity is generally based on the rate of photosynthesis. Potential of carbon concentration related to the concentration of chlorophyll in phytoplankton for photosynthesis process itself influenced by the concentration of chlorophyll, especially chlorophyll-a, as well as the intensity of sunlight. Primary productivity value can be used as an indication of the fertility level an aquatic ecosystem. Chlorophyll-a highly affect the size of primary productivity in the waters. Therefore, chlorophyll-a concentrations in an aquatic ecosystem can be used as one of the indicator of abundance of phytoplankton which can be indicated from the primary productivity associated with potential carbon sink of phytoplankton. The information on the relationship between primary productivity with the concentration of chlorophyll-a and its relationship with the factor of chemical-physics of the lakes in University of Indonesia during dry season are still very limited. Therefore, it is necessary to determine the concentration of chlorophyll phytoplankton in relation to primary productivity and carbon sink in the dry season, because the season is one of the limiting factor of primary productivity. This study was conducted to analyze the potential of the carbon content and chlorophyll phytoplankton, in six lakes University of Indonesia, Depok. 6th Int'l Conference on Agriculture, Environment and Biological Sciences (ICAEBS'16) Dec. 21-22, 2016 Kuala Lumpur (Malaysia) https://doi.org/10.15242/IIE.A1216021 119