A Preliminary Assessment of Mercury and Cadmium Concentration in Coastal Fish of Island Garden City of Samal, Davao del Norte

Abstract

Heavy metal concentration in marine ecosystems poses potential risks to fisheries resources and public health due to the persistence and bioaccumulative nature of toxic metals. This study conducted a preliminary assessment of mercury (Hg) and cadmium (Cd) concentrations in selected reef fish species from the Island Garden City of Samal (IGACOS), Davao del Norte, Philippines. A quantitative research design was employed, involving field sampling and laboratory analysis of fish muscle tissues collected sampling stations distributed across the Babak and Kaputian districts. Mercury and cadmium concentrations were determined using Atomic Absorption Spectrophotometry (AAS) following standardized analytical procedures. Results showed that Hg concentrations ranged from 0.0177 to 0.0536 mg·kg⁻¹, while Cd concentrations ranged from non-detectable levels to 0.0200 mg·kg⁻¹. All recorded values were below the maximum permissible limits established by the Food and Agriculture Organization and the European Commission for fishery products. Independent samples t-test results indicated no significant differences in Hg (p = 0.276) and Cd (p = 0.295) concentrations between the two districts. Slightly higher mercury levels were observed in the carnivorous species Cephalopholis miniata, suggesting trophic-level influences on metal accumulation. The findings indicate generally low levels of Hg and Cd contamination in the sampled fishery resources and provide baseline information for environmental monitoring, fisheries management, and future assessments of marine ecosystem health in IGACOS.