Oxygenation variability off Northern Chile during the last two centuries

Abstract The Peru Chile Current ecosystem is characterized by high biological productivityand important fisheries. Although this system is likely to be severely affected by cli-mate change, its response to current global warming is still uncertain. In this paper 5 we analyze 10–166year old sediments in two cores collected in Mejillones Bay, ananoxic sedimentary setting favorable for preservation of proxies. Based on a 166yearchronology we used indicators of bottom water oxygenation proxies (Mo, V, S, and the(lycopane+ n -C 35 )/ n -C 31 ) ratio) and surface water productivity (biogenic opal, counts ofdiatom valves, biogenic Ba, organic carbon and chlorins) to reconstruct environmental 10 variations in Mejillones Bay. We find that at decadal scales, and during the last twocenturies, a shift in the coastal marine ecosystem off Northern Chile took place whichwas characterized by intense ENSO-like activity and large fluctuations in biological ex-port productivity, in bottom water oxygenation, and increased eolic activity (inferredfrom Ti/Al and Zr/Al). On top of this short-term variability, a gradual increase of sulfidic