The Species Composition of Phytoplankton and Nutrient Content in the Nipa Nypa fruticans Ecosystem on the West Coast of Aceh, Indonesia

Nipa Nypa fruticans grows in estuaries that are affected by sea waters and freshwater. Therefore, the Nipa habitat develops into an area of water mass circulation and becomes rich in nutrients that trigger the growth of phytoplankton as the primary producer in the aquatic ecosystem. This study aimed to examine the species composition and distribution of phytoplankton and nutrient content in the nipa ecosystem on the west coast of Aceh, Indonesia. It was conducted from July 2018 to September 2019 and sampling was carried out in two areas, namely Kuala Bubon Aceh Barat district and Kuala Tadu, Nagan Raya district. A total of 100L of surface water samples was taken from three points at each location. Subsequently, the water was filtered with a plankton net mesh No. 25 and preserved with a 4% Lugol solution. The water sample from both locations was also analyzed for nitrogen and phosphorus contents. The results showed that there were 20 species of phytoplankton in both sampling locations, with Kuala Bubon consisting of 13 species with density of 160.87 cells L-1, and 15 species in Kuala Tadu with density of 273.64 cells L-1. Haramonas sp. was the dominant species in Kuala Bubon, while Amphisolenia bidentata was dominant in Kuala Tadu. Based on the nutrient content (nitrate+nitrite and phosphate), the average nutrient content in Kuala Bubon was 1.31 mg L-1 (mesotrophic) and 0.12 mg L-1 phosphate (hypertrophic). Meanwhile, Kuala Tadu had 1.078 mg L-1 nitrate+nitrite (mesotrophic) and phosphate, 0.22 mg L-1 (hypertrophic) waters. These findings are an early indication that the estuary of Kuala Bubon and Kuala Tadu have been contaminated by organic matter.