Phytoplankton Community Structure as an Indicator of Eutrophication Risk in an Industrialized Tropical Bay: A Case in Bojonegara, Banten Bay, Indonesia
Endang S. Srimariana *
Department of Marine Science and Technology, Faculty of Fisheries and Marine Sciences, IPB University, Jl. Agatis Darmaga, Bogor 16680, Indonesia.
Alexandra M. D. Rahardjo
Department of Marine Science and Technology, Faculty of Fisheries and Marine Sciences, IPB University, Jl. Agatis Darmaga, Bogor 16680, Indonesia.
Dea Fauzia Lestari
Department of Marine Science and Technology, Faculty of Fisheries and Marine Sciences, IPB University, Jl. Agatis Darmaga, Bogor 16680, Indonesia.
Nadya Cakasana
Department of Marine Science and Technology, Faculty of Fisheries and Marine Sciences, IPB University, Jl. Agatis Darmaga, Bogor 16680, Indonesia.
Meutia Samira Ismet
Department of Marine Science and Technology, Faculty of Fisheries and Marine Sciences, IPB University, Jl. Agatis Darmaga, Bogor 16680, Indonesia.
Tumpak Sidabutar *
Research Center for Biota System, National Research and Innovation Agency (BRIN), Jl. Raya Jakarta Bogor Km 46, Cibinong, Bogor, Indonesia.
Sulistiono Sulistiono *
Study Program of Marine Science and Technology, Faculty of Fisheries and Marine Sciences, IPB University, Jl. Agatis, IPB Dramaga Campus, Bogor 16680, Indonesia.
*Author to whom correspondence should be addressed.
Abstract
Industrial and residential activities can influence nutrient availability and phytoplankton community structure in tropical coastal ecosystems. This study evaluated spatial and temporal variations in phytoplankton communities and their relationships with physicochemical conditions along the river–estuary–sea gradient of Bojonegara coastal waters, Banten Bay, Indonesia. Water and phytoplankton samples were collected from six stations representing riverine, estuarine, and marine environments during five sampling periods in 2023. Phytoplankton identification revealed 43 genera distributed among five classes: Bacillariophyceae, Chlorophyceae, Cyanophyceae, Dinophyceae, and Euglenophyceae. Bacillariophyceae and Cyanophyceae were the principal components of the phytoplankton community. Bacillariophyceae were generally associated with marine environments characterized by higher salinity and greater water transparency, whereas Cyanophyceae were more prominent in riverine and estuarine environments influenced by freshwater inputs. The Shannon–Wiener diversity index ranged from 0.979 to 1.769, indicating spatial differences in community diversity. Physicochemical measurements demonstrated variations in salinity, transparency, turbidity, nitrate, and phosphate concentrations among the sampling stations. Principal component analysis indicated that the first two components explained approximately 70.80% of the total variance. Bacillariophyceae and Dinophyceae were associated with higher salinity and transparency, while Chlorophyceae and Euglenophyceae showed associations with nutrient variables. These findings indicate that phytoplankton composition reflects environmental gradients in Bojonegara coastal waters and may provide complementary biological information for monitoring nutrient enrichment and potential eutrophication risk in industrially influenced tropical coastal environments.
Keywords: Phytoplankton community structure, eutrophication risk, tropical coastal ecosystem, nutrient enrichment, physicochemical parameters