Disentangling metal diffusion from a highly industrial harbor and its bioaccumulation in different zooplankton groups

Metal pollution in harbors has long threatened coastal ecosystems. However, elucidating their bioaccumulation and diffusion impacts is challenging due to complex marine communities—with zooplankton as an indicator. Metals in seawater, suspended particulate matter, and isolated zooplankton groups were analyzed using inductively coupled plasma mass spectrometry. As hypothesized, metals were significantly bioaccumulated by zooplankton (log BCF > 3.7). Seawater metal distribution was homogenous, while suspended particulate matter (SPM) showed wider variations, both having high Metal Pollution Index (MPI) levels along harbor entrances. Bioaccumulation in zooplankton groups varied significantly, with Fe, Cu, Zn, and Cd being the most bioaccumulative. The abundance and dominance of copepods drive metal accumulation in bulk zooplankton communities, with decreasing patterns towards the sea. This highlights the impact of harbor activities on metal diffusion and the potential long-range transport of pollutants, which is crucial for developing ecological monitoring — highlighting the role of dominant zooplankton groups in driving metal distribution.