Evaluation of trophic status of Deudap Beach and Lhok Reudeup Beach, Nasi Island, Aceh Province, based on nitrate and phosphate concentration, and chlorophyll-a abundance

The investigation of the trophic status based on the nitrate-phosphate correlation and chlorophyll-a abundance in Deudap beach and Lhok Reudup beach, Pulau Nasi, Aceh were carried out in November 2018. Determination of sampling location based on purposive sampling method. The total nitrate, total phosphate concentration, and chlorophyll-a abundance determined by Ultra Violet-Visible (UV-Vis) spectrophotometre which was confirmed from the real-time NOAA database. The results of the chlorophyll-a abundance analysis showed that the abundance of chlorophyll-a in the surface layer ranges 0.7 - 0.11 mu g / L. Total nitrate and total phosphate concentrations at deudap beach and lhok reudup in the surface layer ranges 260 - 183 mu g / L and 9.4 - 6.8 mu g / L. Furthermore, the results indicate that the phenomenon of the chlorophyll-a abundance is closely related to the availability of the macronutrient of nitrate and phosphate. Based on the correlation between total nitrate-phosphate and chlorophyll-a abundance in deudap beach and lhok reudup, Nasi Island are included in the category of oligotrophic waters.