A Spatio-Temporal Analysis on the Composition and Abundance of PhytoplanktoninSegara Anakan Lagoon Area

SegaraAnakan Lagoon (LSA) is a dynamic estuary with humid tropical climate, of which water fluctuates as the result of water hydrodynamics and changes in monsoon. The LSA area is influenced by natural factors (estuary of freshwater flow of Citanduy Watershed and high sedimentation) and various anthropogenic factors. Such conditions may influence the water's ecological conditions. This research aims at examining such ecological changes as phytoplankton's biological indicators (composition and abundance), since phytoplankton is able to naturally respond to environmental changes. The method is conducted with spatially in-situ measurement on phytoplankton abundance in the seven areas of SegaraAnakan Lagoon with different characteristics: (1) TPI and Port of Majingklak; (2) Pelawangan Barat LSA bordering the Indian Ocean; (3) Locks of Cikonde and Cimeneng Rivers; (4) Mangrove Forest; (5) KampungLaut Community Settlement; (6) Conservation Area "Mina Wisata" Ujung Alang; (7) Floating Net Culture. A temporal approach (time series) is then conducted for 1 year based on the representativeness of monsoon: West, Transition I, East and Transition II. Phytoplankton abundance is quantitatively analyzed using Lackey Drop Microtransect Counting method, and for ease of spatio-temporal interpretation, the results are displayed in the form of thematic map using Arc Gis 10.2 software. The analysis results show that spatially, the phytoplankton abundance in the seven areas ranges from 4474.80 ± 3408.25-8712.00 ± 6444.89 indv/L. Meanwhile, with the temporal analysis, the highest abundance takes place in the Transition I season of 9956.57 ± 5300.23 indv/L, and the lowest is in West season of 4129.71 ± 3139.88 indv/L. In the whole spatio-temporal period, the phytoplankton composition is dominated by Division Chrysophyta, and then respectively by Divisions Chlorophyta, Cyanophyta, Pyrophyta and Euglenophyta. The composition and abundance of freshwater, estuary and sea phytoplankton are spatio-temporally, evenly distributed in the seven areas, which is expectedly resulted from the Flushing Time mechanism from freshwater flow of Citanduy Watershed and the influence of water hydrodynamics of Indian Ocean at Pelawangan Barat entering the lagoon area. (paper)