Volumen 44 - Número 3: 571-582 | 2009
Article

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Temporal fluctuations of nearshore ichthyoplankton off Valparaíso, central Chile, during the ENSO cycle 1997-2000

Mauricio F. Landaeta^1*, Katherine Schrebler¹, Claudia A. Bustos^2,3, Jaime Letelier^4,5 and Fernando Balbontín¹

¹Facultad de Ciencias del Mar y de Recursos Naturales, Universidad de Valparaíso, Casilla 5080, Reñaca, Viña del Mar, Chile
²CIEN Austral, Centro de Investigación en Nutrición, Tecnología de Alimentos y Sustentabilidad, Universidad Austral de Chile, sede Puerto Montt, Casilla 1327, Puerto Montt, Chile
³Programa de Doctorado en Acuicultura, Universidad Católica del Norte, Coquimbo, Chile
⁴Programa de Postgrado en Oceanografía, Departamento de Oceanografía, Universidad de Concepción, Casilla 160-C, Concepción, Chile
⁵Instituto de Fomento Pesquero, Blanco 893, Valparaíso, Chile

*This email address is being protected from spambots. You need JavaScript enabled to view it.

Between January 1997 and December 2000 daily data of sea surface temperature, sea level height and Ekman transport were taken, together with biweekly and monthly sampling of ichthyoplankton in a coastal station located in Valparaíso Bay. Samples were collected through vertical tows from 50 m depth to surface with a conical net. From a total of 103 zooplankton samples, 71 samples had positive presence of ichthyoplankton; a total of 10,646 eggs and 1,189 larval fish were separated, corresponding to 6 and 20 taxa, respectively. Eggs specific composition was dominated by Engraulis ringens (35.5%), Merluccius gayi (32.7%) and Sardinops sagax (23.3%). For larvae, dominant species were M. gayi (53.5%), S. sagax (16.1%), E. ringens (13.7%), Hygophum bruuni (3.0%) and Prolatilus jugularis (2.9%). Specific taxa of both eggs and larvae showed fluctuations of their abundance at seasonal scale and according to the warm and cold phases of El Niño-Southern Oscillation (ENSO), similar to those observed in the physical time series data. Despite the strong differences in egg abundance in the period, only M. gayi eggs showed a significant increase during La Niña phase. In the ENSO 1997-2000 cycle, sea level height and Ekman transport showed strong differences between ENSO phases, but the whole diversity of the larval fish community was not affected. No significant differences in the diversity indices were detected, for Shannon index or for Simpson index. However, multivariate analyses showed that larval assemblages were significantly stratified according to the warm and cold phase of ENSO. Therefore, composition of ichthyoplankton was significantly affected by the ENSO cycle in the coastal area of Valparaíso between 1997 and 2000.

Key words: Larval fish, seasonality, Engraulis ringens, Sardinops sagax

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