Understanding pollutant uptake by biota in the surrounding waters as well as the spatial linkages and dynamics of these pollutants is increasingly important. The Barnacle Baseline project aims to understand regional and seasonal uptake of Contaminants of Emerging and Known Concerns (CECs/CKCs) in Florida’s largest estuary, Tampa Bay, using acorn barnacles (Amphibalanus amphitrite and Amphibalanus eburneus). Barnacles are tolerant of a wide range of salinities and temperatures and have a sessile adult stage, making them an excellent species for site-specific pollution studies and for identifying potential sources of contaminants. To recruit and collect these organisms, glass tiles were arranged within a PVC frame and placed at 17 diverse sites around Tampa Bay. These sites include areas near a variety of contaminant sources including wastewater treatment plants, stormwater and septic systems, as well as control sites. Once the glass tiles were collected, they were photographed for percent cover and community composition analysis, and barnacle soft tissues dissected from each individual. Tissues from each site and season (wet or dry) were analyzed with GC/MS to determine specific CEC/CKC presence and concentrations. Barnacles grown on the tiles during Florida’s wet season (May-October) were collected and processed separately from the barnacles of the dry season (November-April) to test the hypothesis that increased rainfall results in elevated concentrations of CECs and CKCs around the Bay. Results from barnacle samples collected at the conclusion of the 2025 wet season will be presented. Using this often-overlooked invertebrate species to gain insights on contaminant sources within Tampa Bay will allow us to further understand pollution threats affecting not only marine species, but also the threats to humans.