Distribution and life cycle of Calanus chilensis and Centropages brachiatus (Copepoda) in Chilean coastal waters:a GIS approach

Abstract

Calanus chilensis and Centropages brachiatus are 2 of the most abundant species of copepods (Crustacea) off the Chilean coast. However, knowledge of their life cycle and distribution is fragmentary. We have analysed the distnbution of both species in Chilean coastal waters by means of a Geographic Information System (ARC/INFO). We studied vertically integrated (0 to 100 m) zooplankton samples and ancdlary physical oceanographic data collected during 1989 by the Instituto de Fomento Pesquero, Chlle. Point estimates of abundance and physical data were transformed to a grid format in ARCANFO. We show that both species are abundant within 10 km from shore, and that high abundances further offshore may be interpreted as the result of advection. We also show that both species remain year-round in the upper water column with no evidence of seasonal vertical nugration. We then discuss potential Me cycle mechanisms that might explain their dominance in the coastal area of the Humboldt Current ecosystem.

Spatial distribution of Calanus chilensis off Mejillones Peninsula (northern Chile): ecological consequences upon coastal upwelling

“…Previous studies have suggested that this copepod may exhibit continuous production year-round in northern Chile (Escribano & McLaren 1999), is very abundant and widely distributed along the coast off northern Chile (Gonzalez & Marin 1998), and their populations appear strongly associated with upwelling centres (Escribano 1998). Although previous laboratory experiments ( Escribano et al 1997) indicated that food may affect development and growth rates, more recent field data suggest that food might be sufficiently high to maintain high growth rates in nearshore areas at all seasons (Escribano & McLaren 1999, Escribano & Hidalgo 2000a, Ulloa et al 2001.…”

Production of Calanus chilensis in the upwelling area of Antofagasta, northern Chile

“…Although in vertically stratified systems zooplankton can use current shear to maintain vertical position (e.g. Peterson et al 1979), C. chilensis copepodids tend to accumulate offshore because of advection (Gonzalez & Marin 1998). Younger copepodids were relatively more abundant at the outermost stations in the Bay of Mejillones, whereas older copepodids and adults predominated in the much smaller populations at stations in the inner and southern parts of the bay (Fig.…”

“…Wroblewski 1980). This seems to strongly affect distribution of C. chilensis in northern Chile (Gonzalez & Marin 1998). Although in vertically stratified systems zooplankton can use current shear to maintain vertical position (e.g.…”

Sublittoral soft bottom communities and diversity of Mejillones Bay in northern Chile (Humboldt Current upwelling system)

“…This oceanographic pattern can be aVected by the large-scale El Niño Southern Oscillation (ENSO) (e.g. Taraba 1959;Brandhorst 1971;Navea and Miranda 1980;Fonseca 1989;Arntz and Fahrbach 1991;Fuenzalida 1992a, b;Morales et al 1996;Gonzalez and Marín 1998;Strub et al 1998;Escribano 1998;Ulloa et al 2001;Arntz et al 2006). Monitoring the sea surface temperature oV Chile and Peru has illustrated that ENSO shows an interannual climate oscillation between warm phases (El Niño: EN) and enhanced cold phases (La Niña: LN).…”