Influence of coastal upwelling and El Niño–Southern Oscillation on nearshore water along Baja California and Chile: Shore‐based monitoring during 1997–2000

Abstract

[1] In order to determine the sensitivity of coastal upwelling tracers to seasonal wind forcing and El Niño-Southern Oscillation (ENSO) off Baja California and Chile, nearshore salinity, cadmium (Cd), and nutrients phosphate, silicate, nitrate+nitrite were monitored in surf zone waters at six locations along the North and South American coasts during 1997-2000. The clearest responses to upwelling favorable wind forcing were observed at the southern tip of Baja California (23.3°N) and off central-southern Chile (36.5°S). Upwelling tracers at 23.3°N were also the most sensitive to El Niño: average summer Cd and nutrient enrichments were 60% lower following El Niño than during the previous non-El Niño upwelling season. At two sites on the northern and central Chile coasts, conditions associated with El Niño resulted in salinity anomalies >1. Such large shifts in nearshore water properties suggest it may be possible to reconstruct past ENSO patterns from geochemical paleonutrient/paleosalinity proxy records preserved in nearshore archives such as mollusc or foraminifera shells. INDEX TERMS: 4215

Solid phase phosphorus species and preservation of fish remains in marine sediments of areas of high primary productivity and oxygen seasonality (36°S, central South Chile)

“…Variations in the strength of the OMZ are probably important to determine solid phase P dynamics in the study area. This conclusion is in agreement with observations made by Takesue et al (2004) who found that the ratio Cd/P in upwelled waters during spring-early summer in Coliumo Bay (central Chile) was lower than expected (0.27 × 10 -3 mmol mol -1 ) compared to the California upwelling system (0.35 × 10 -3 mmol mol -1 ). These authors suggested that the proportion of Cd:P in upwelling waters could be altered when surface sediments are anoxic since Cd precipitates into pore waters as a sulfide and P is released from sediments.…”

Effects of disturbance on the diversity of hard-bottom macrobenthic communities on the coast of Chile

“…The main upwelling area is located at a distance of approximately 40 km southwest of the study area (Acuña et al 1989). The main subsurface source of upwelling off northern Chile is the subsurface equatorial water (Morales et al 1996), which is characterized as being relatively cold, oxygen-poor water, with a high nutrient content (Silva & Konow 1975), leading to the high productivity of this coastal region (Acuña et al 1989, Daneri et al 2000, Takesue et al 2004.…”

Diversidad, distribución y abundancia de especies en ensambles intermareales rocosos

“…Uno de ellos es la variación espacial en ocurrencia, frecuencia e intensidad de la surgencia costera, con efectos diferenciales entre especies, niveles tróficos, grupos funcionales o ensambles locales (e.g., Moreno et al 1998, Vásquez et al 1998, Camus & Andrade 1999, Broitman et al 2001, Nielsen & Navarrete 2004, Lagos et al 2005, Wieters 2005, Lagos et al 2008. Otro es El Niño-Oscilación del Sur, que afecta diferencialmente la riqueza, abundancia y composición de las comunidades del intermareal rocoso, pero a su vez puede modificar la frecuencia e intensidad de la surgencia (e.g., Camus & Ojeda 1992, Castilla & Camus 1992, Camus 1994, Moreno et al 1998, Takesue et al 2004, Thiel et al 2007. Datos recientes de la composición de cuatro ensambles intermareales del norte de Chile entre 21º y 30ºS, muestran que su nivel de recambio de especies es muy alto en espacio (46-57% entre pares de ensambles, media ~50%; Camus, datos no publicados) y tiempo (promedio estacional ~40-50% en cada ensamble; Camus 2008), lo cual podría ser una característica de las comunidades en esta región.…”