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Oxygenation variability off Northern Chile during the last two centuries

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Author(s): J. A. Díaz-Ochoa | S. Pantoja | G. J. De Lange | C. B. Lange | G. E. Sánchez | V. R. Acuña | P. Muñoz | G. Vargas

Journal: Biogeosciences Discussions
ISSN 1810-6277

Volume: 7;
Issue: 4;
Start page: 4987;
Date: 2010;
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ABSTRACT
The Peru Chile Current ecosystem is characterized by high biological productivity and important fisheries. Although this system is likely to be severely affected by climate change, its response to current global warming is still uncertain. In this paper we analyze 10–166 year old sediments in two cores collected in Mejillones Bay, an anoxic sedimentary setting favorable for preservation of proxies. Based on a 166 year chronology we used indicators of bottom water oxygenation proxies (Mo, V, S, and the (lycopane+n-C35)/n-C31) ratio) and surface water productivity (biogenic opal, counts of diatom valves, biogenic Ba, organic carbon and chlorins) to reconstruct environmental variations in Mejillones Bay. We find that at decadal scales, and during the last two centuries, a shift in the coastal marine ecosystem off Northern Chile took place which was characterized by intense ENSO-like activity and large fluctuations in biological export productivity, in bottom water oxygenation, and increased eolic activity (inferred from Ti/Al and Zr/Al). On top of this short-term variability, a gradual increase of sulfidic conditions has occurred being even more intensified since the early 1960s.

Tango Jona
Tangokurs Rapperswil-Jona

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