Increased nutrients from aeolian-dust and riverine origin decrease the CO2-sink capacity of coastal South Atlantic waters under UVR exposure Jabalera Cabrerizo, Marco Carrillo Lechuga, Presentación Villafañe, Virginia E. Medina-Sánchez, Juan Manuel Helbling, E. Walter Increases in ultraviolet radiation (UVR) levels due to the ongoing stratification of water bodies and higher nutrient concentrations either through riverine or aeolian-dust-inputs are expected in the near future in coastal surface waters. Here, we combined remote-sensing data of particulate organic carbon (POC; 1997–2016 period), observational data of solar radiation (1999–2015 period), and a mid-term experimental approach with coastal plankton communities from South Atlantic Ocean (SAO) to test how the interaction between increased nutrients by riverine and aeolian-dust inputs and high UVR may alter the community dynamics and the CO2 sink capacity of these ecosystems in the future. Our results show a decline ∼ 27% in the sink capacity of the coastal ecosystems regardless of the nutrient source considered and under high UVR levels. This decreased CO2 uptake was coupled with a high dynamic photoinhibition and dark recovery of photosystem II and shifts in the community structure toward the dominance by nano-flagellates. Moreover, remote-sensing data also evidences an incipient tipping point with decreasing POC values in this area over the annual planktonic succession. Therefore, we propose that to continue this climate and human-mediated pressure, these metabolic responses could be strengthened and extended to other productive coastal areas. 2025-01-24T10:06:05Z 2025-01-24T10:06:05Z 2017-12 journal article Limnology and Oceanography https://hdl.handle.net/10481/100222 10.1002/lno.10764 eng http://creativecommons.org/licenses/by-nc/4.0/ open access Atribución-NoComercial 4.0 Internacional John Wiley & Sons