Resumen del producto

The California Current region is a high dynamic area with oceanographic processes of different spatial and temporal scales which affect the zooplankton species distribution. During 2002, two antagonist processes were noted simultaneously in the area: an anomalous subarctic water intrusion coming from the north which persisted until 2006 and El Niño event which ended until 2004. Coincidence of both events has motivated controversy about their combined effect in the ecosystem since depending with the variables and taxonomic groups analyzed, the influence of one of them seems to be strongest than the other one. Birds seem to be more affected by the El Niño event, while zooplankton composition was driven by the subarctic intrusion. In this work we analyzed the combined effect of both events during 2002 and 2003, period in which zooplankton Bongo tows were done during April and October. Results showed that the dominant fish larvae species were the same to that reported in the historic data. Although April 2003 had lower species richness, mostly dominated by temperate-subarctic species (even compared with the historic data since 1979); during the October surveys (2002 and 2003) the abundance of tropical and subtropical species were higher and the species richness had unusual high values (especially during 2003) compared with the historic series, suggesting a stronger effect of El Niño on the distribution and abundance of the fish larvae to that supported by the intrusion of subarctic water. Although the statistical analysis showed that the sea surface temperature drive the latitudinal distribution of the fish larva species, the larval fish assemblages was determined mainly by the geostrophic flow. The presence of cyclonic and anticyclonic gyres front of Punta Eugenia and Bahía Vizcaino seems to determine the location of the transition zone between the northern temperate-subarctic fauna and the southern tropical-subtropical fauna. The establishment of more intense eddies during the fall of both years limited the distribution toward the south of the temperate-subarctic species, diminishing the effect of the subarctic water intrusion on the species distribution. In contrast, during April of both years, less intense eddies allowed a southernmost distribution of the temperate-subarctic species facilitate by a strongest southward flow of the California Current.

Palabras clave: dióxido de carbono; cambio climático; El Niño; Intrusión de Agua Subártica

Para obtener una copia del documento contacta la personal de la biblioteca a través del correo bibliocicimar{a}ipn.mx