Long Term Monitoring Activities to Investigate the Colonization Dynamics of Non-Indigenous Seaweeds in Transitional Waters

The species composition and the biomass of macroalgal assemblages at two stations in the Mar Piccolo of Taranto have been investigated during the period 2011–2023. Occurrence and biomass trends of non-indigenous species (NIS), compared to those of native ones, highlighted the potential impacts on the local environment. The life histories of the different species and the influence that human activities likely exert with repetitive introductions might explain how at Station A the native seaweed biomass seems to be influenced by NIS. In contrast, at Station B where the native fraction of macroalgal species did not show any evident negative effects, notwithstanding the huge amount of Hypnea corona mainly in the warm season.