The accumulation of heavy metals in ecosystems and their transfer through the food chain pose significant risks to both human health and aquatic life. In the research, the presence of toxic metals in the marine environment because of thermal power plants and industrial facilities located on the Karabiga coast was evaluated, and the bioaccumulation levels of heavy metals in algae species were determined. Heavy metal (Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) analyses were performed using the ICP-OES device in sediment and macroalgae samples taken from 5 stations in the Karabiga coastal region in the Northwestern Anatolia of Turkey in September 2023. To assess the extent of heavy metal pollution, several indices were calculated, including the Enrichment Factor (EF), Pollution Factor (CF), Pollution Load Index (PLI), and Geoaccumulation Index (Igeo), which provide insights into the sources and levels of contamination. No significant pollution was detected based on the Pollution Indexes. All measured heavy metal concentrations in sediment samples were below the regulatory limits set by the WWQG (2021) and classified as Class A quality according to the SACS (2015) guidelines, indicating minimal pollution in the study area. Macroalgae species, particularly Cladophora sericea and Gongolaria barbata, showed elevated levels of Cu, Pb, and Zn, exceeding regulatory limits set by ANZFA (2005) and EC (2011). Potential risk calculation methods for human health were performed on 5 analyzed macroalgae samples. Considering the HI values for macroalgae, no metal was detected with a HI value greater than 1, therefore no potential health risks are expected.