Articles | Volume 8, issue 1
Biogeosciences, 8, 137–146, 2011
Biogeosciences, 8, 137–146, 2011

Research article 20 Jan 2011

Research article | 20 Jan 2011

Oxygenation variability in Mejillones Bay, off northern Chile, during the last two centuries

J. A. Díaz-Ochoa1,*, S. Pantoja1, G. J. De Lange2, C. B. Lange1, G. E. Sánchez1, V. R. Acuña1, P. Muñoz3, and G. Vargas4 J. A. Díaz-Ochoa et al.
  • 1Departamento de Oceanografía and Centro de Investigación Oceanográfica en el Pacífico Sur Oriental (FONDAP-COPAS), Universidad de Concepción, Casilla 160-C, Concepción, Chile
  • 2Geochemistry Department, Faculty of Geosciences, Utrecht University, Budapestlaan 4, 3584 CD, Utrecht, The Netherlands
  • 3Departamento de Biología Marina, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile
  • 4Departamento de Geología, Universidad de Chile, Casilla 13518 Correo 21, Plaza Ercilla 803, Santiago, Chile
  • *now at: Departamento de Ciencias y Recursos Naturales, Universidad de Magallanes, Avenida Bulnes 01855, Casilla 113-D, Punta Arenas, Chile

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 from Mejillones Bay, an anoxic sedimentary setting favorable for the preservation of proxies. Based on a 166-year chronology, we used proxies of bottom-water oxygenation (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. During the last two centuries, a shift took place in the coastal marine ecosystem of Bahia Mejillones at decadal scales. This shift was characterized by intense ENSO-like activity, large-scale fluctuations in biological export productivity and bottom water oxygenation, and increased eolian activity (inferred from Ti/Al and Zr/Al). This short-term variability was accompanied by a gradual increase of sulfidic conditions that has intensified since the early 1960s.

Final-revised paper