Near Sto. Tomas Cove, multiple aquafarms were operational along the coastal area, specifically referred as the Techno Demo farms, which are monitored by the Bureau of Fisheries and Aquatic Resources via monthly water sampling. These Techno Demo farms are found in the coastal waters of Sto. Tomas and Rosario, La union. However, the dissolved organic matter (DOM) impact of these aquafarms in the coastal water are still unknown. Thus, in this study, to understand the DOM contribution of these aquafarms, physicochemical analysis and UV-Vis absorbance measurements were performed to derive spectral optical properties. The absorption spectra measurements were used to calculate the absorption coefficient, spectral slope coefficient and the specific UV absorbance which estimate the chromophoric DOM, the composition and structure of DOM, and the aromaticity, hydrophobicity, and molecular weight of DOM, respectively. Both physicochemical and spectral absorbance analyses were compared to understand the characteristics of dissolved organic matter found. The result was able to distinguish the difference between the two locations based on their spectral properties supported by their physicochemical properties. The phosphate and the TSS level were found related to the Napierian absorption coefficient at 254nm and 355nm, respectively. The study concluded that the aquafarms significantly have higher absorption coefficients due to high CDOM concentration than their respective control no take zones, indicating possible source mariculture pollution.
