Studies covering key elements of the marine ecosystem based on current and long-term data have made it possible to assess both the current situation in terms of copper concentrations in commercially used fish and benthic plants and in surface bottom sediments, as well as enabled the analysis of the temporal variability of copper levels in relation to changes in its inflow to the southern Baltic Sea. By applying the threshold values, determining the boundary between good and not good status of the marine environment, set in this study, it was found that good environmental status has been achieved in the case of Cu in seawater and plants and has not been achieved in the case of sediments and fish for consumption. The study showed that climate change, the main feature of which is an increase in seawater temperature, significantly impacts the distribution and levels of copper in individual elements of the marine environment. It influences the vegetative season length and bioaccumulation efficiency and is of key importance for copper toxicity.
