RESPUESTA DE LA COMUNIDAD DE LARVAS DE PECES EN EL SUR DE LA CORRIENTE DE CALIFORNIA ANTE LA INTRUSIÓN ANÓMALA DE AGUA SUBÁRTICA Y EL EVENTO EL NIÑO 2002-2004

Abstract

The California Current (CC) is a system with strong oceanographic changes from different spatial-temporal scale affecting the zooplankton composition and distribution. Since 2002, the study area was influenced by two processes from different nature, the subarctic water intrusion (2002-2006) and EL NIÑO (2002-2004) event. This work analyze the effect of both processes on the composition and distribution of fish larvae from the southern region of the CC during the years 2002 and 2003, period in which zooplankton oblique Bongo tows were made. El Niño (EN) event and the subarctic water intrusion (ASA), affecting in a different way the larval fish composition and abundance depending with the season. In April 2003, the presence of ASA potentiates the cooling of the ecosystems during the spring, temperate-subarctic species were dominant and richness as well as larval abundance diminished, not being possible to observe the effect of EN. In October 2003, EN effect is potentiates with the warming of the fall month, increasing the richness as well as the abundance of tropical-subtropical species and diminishing the ASA effect. In April, the coast-ocean abundance gradients are defined by upwelling processes as well as the main flux of the CC, while in October the CC weakening and the mesoscale eddies formation, allow the arrive of mesopelagic species near the coast, causing latitudinal gradients in the distribution. Although the physical evidence indicate that the EN was finished in May 2003, the extension toward the north of the distribution of the tropical-subtropical community, plus the unusual high richness values, suggest that EN event was present at least until October 2003. In general, the ASA intrusion caused the presence of different assemblages to those described previously in the study area, because a differential species transport of temperate-subarctic species toward the south, an increase in the abundance of the resident species and the absence of some other species that normally are frequent or abundant in the area.