The Plankton Composition from the Lagoon to the Marine Entrance at the West Part of Segara Anakan Mangrove Ecosystem in Cilacap

There was a unique brackish water ecosystem and affected a chance in the plankton composition at lagoon and riverside in Segara Anakan Cilacap. This study aimed to map phytoplankton and zooplankton composition consisting of freshwater and marine plankton from the lagoon to the marine entrance in the west part of Segara Anakan Cilacap. The survey method was taken with purposive random sampling in fourteen stations and four replicates with new and full moon conditions from March to April 2018 in a wet season. The result showed 52 species of plankton. All species belonged to phylum Cyanophyta (9 species), Chlorophyta (13 species), Chrysophyta (19 species), Euglenozoa (2 species), Rotifera (2 species) and Arthropoda (7 species). Of the 52 species collected in all stations and replicates, phytoplankton has a greater species richness (41 species) than zooplankton (11 species). And also, freshwater plankton (47 species) has a higher species richness than marine plankton (5 species) due to the wet season condition causing freshwater enters brackish water. The largest freshwater of River Citanduy enters the brackish water of Segara Anakan mangrove ecosystem in Cilacap and causing the freshwater phytoplankton abundance, especially Staurastrum sp. in inland waters of Segara Anakan Cilacap.