Ecological Correspondence Between the Metabolic Composition of Anadara granosa (Bivalvia Class – Mollusca Phylum) and Nutrient Enrichment Pressure in Cirebon Bay, Indonesia

Tropical coastal ecosystems, vital habitats for economically significant marine species, face increasing threats from eutrophication driven by human-induced nutrient pollution. This study investigated the metabolomic profile of Anadara granosa, a marine bivalve, to identify metabolites indicative of eutrophic conditions. Conducted in Cirebon Bay, Indonesia, the research spanned five locations reflecting varying eutrophication levels. Bottom-layer water samples were analyzed for pH, dissolved oxygen, salinity, water transparency, and nutrient concentrations (phosphate, nitrate, ammonia). Proton-Nuclear Magnetic Resonance (Proton-NMR) metabolomics of A. granosa revealed metabolite variations linked to water quality. Eutrophic conditions, prevalent in the bay's northern side, were characterized by inorganic nitrogen levels above 0.2 mg L⁻¹ and phosphate exceeding 0.024 mg L⁻¹. These were linked to urban, aquaculture, and agricultural runoff, driving increased phytoplankton biomass and reduced salinity variability. Metabolomic analysis identified inosine and dimethylglycine as potential biomarkers. Elevated inosine levels in eutrophic environments suggest increased cellular activity due to greater food availability, while higher dimethylglycine concentrations detected in low-nutrient as its role in osmotic regulation. Both metabolites correlated with ammonia concentrations (P < 0.05, R² = 0.631), a key contributor to eutrophication. These findings highlight inosine and dimethylglycine as effective indicators of nutrient enrichment, providing insights into eutrophication's impact on coastal ecosystems and A. granosa's physiological responses.