ANALYSIS DIVERSITY MACROALGAE BASED ON SUBSTRATE IN TARAHAN ISLAND BANTEN

Abstract

Macroalgae play a crucial role in coastal and marine ecosystems as pollution indicators and providers of food resources and habitat, in addition to their economic value. This study was conducted on Tarahan Island, Serang Regency, Banten, from April 26 to May 15 2025, to analyze macroalgae diversity and evaluate water quality. An accidental sampling line transect method was employed for macroalgae data collection, while water quality parameters such as pH, salinity, Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), and Biological Oxygen Demand (BOD) were also measured. Identification results indicated the presence of seven macroalgae varieties from six families, comprising two species from Chlorophyta and five from Phaeophyta. The northern region of Tarahan Island exhibited the highest diversity with a Shannon-Wiener index (H ′) of 1.499 (moderate category), supported by more favorable environmental conditions and substrates. Conversely, the western region showed a significant decrease in diversity, with only three pollution-tolerant species identified, attributed to its proximity to industrial pollution sources. Sargassum polycystum and Sargassum cinereum proved to be the most dominant and widespread species. However, a critical finding was the high TSS levels, reaching 400 mg/L in the north and 333.3 mg/L in the west, substantially exceeding the quality standard of 20 mg/L, indicating significant stress on Tarahan Island's waters from suspended solid concentrations.