Artículo de revista
250 years of sardine and anchovy scale deposition record in Mejillones Bay, northern Chile
Fecha
2008-10Registro en:
PROGRESS IN OCEANOGRAPHY, Volume: 79, Issue: 2-4, Special Issue: Sp. Iss. SI, Pages: 198-207, 2008
0079-6611
Autor
Valdés, Jorge
Ortlieb, Luc
Gutiérrez, Dimitri
Marinovic, Luis
Vargas Easton, Víctor
Sifeddine, Abdel
Institución
Resumen
Marine oxygen-deficient environments with high sedimentation rates and high primary productivity can
provide relevant information regarding variations of ocean–climatic conditions in the past. In the Humboldt
current ecosystem, which now hosts huge populations of pelagic fishes (mainly anchovy and sardine),
fish scale abundance in the sedimentary record may be useful indicators of environmental
change. Here we assess such a proxy record in a 42 cm-long sedimentary core collected from 80 min Mejillones
Bay (23 S, northern Chile). We also analyse fish remains in surface sediment sampled along a
bathymetric transect (from 10 to 110 m water depth) in the same bay. In the core-top record, the fluctuations
of sardine and anchovy scale deposition rates (SDR) agreed with those of industrial catches for
these two species in northern Chile, tending to validate the SDR as a proxy of local fish biomass when
bottom anoxic conditions prevail. However, apparent SDR for records prior to 1820 have probably been
influenced by dissolution processes linked to the oxygenation of the bottom environment of Mejillones
Bay, as suggested by other proxy records. After 1820, the fluctuations in the relative abundance of sardine
and anchovy scales point to alternating warm and cold conditions during about 30 years and then a progressively
cooler period. Since ca. 1870, marked fluctuations of SDR of both species are observed, probably
as a consequence of the onset of a different oceanographic regime characterized by intensified
upwelling, stronger subsurface oxygen deficiency, higher primary productivity, and enhanced ‘‘ENSOlike”
interdecadal variability. While anchovy SDR fluctuated in periods of 25–40 years, only two peak
periods of sardine SDR occurred (late 19th century and late 20th century), suggesting that sardine abundance
depends on other ocean–climatic factors.