Aquatic Sciences Meeting, Albuquerque 2001

CS37 Zooplankton

Date: Tuesday, February 13, 2001, Time: 11:45:00 AM

Location: Aztec

Escribano, R, , Universidad de Antofagasta, Antofagasta, Chile, rescribano@uantof.cl

Giraldo, A, , Universidad de Concepcion, Concepcion, Chile, agiraldo@udec.cl

Marin, V, , Universidad de Chile, Santiago, Chile, vmarin@antar.ciencias.uchile.cl

Hidalgo, P, , Universidad de Concepcion, Concepcion, Chile, pahidalg@udec.cl

POPULATION DYNAMICS OF CALANUS CHILENSIS IN THE COASTAL UPWELLING SITE OFF MEJILLONES, NORTHERN CHILE: RETENTION VS ADVECTION

We analyzed the distribution of Calanus chilensis (copepodids and adults) along with oceanographic data off Mejillones Bay (Northern Chile). Samples were collected inside and outside of an upwelling filament during January 2000. Body length (FL), dry weight (DW), oil sac volumen (OSV), gonadal development (GI) and a condition index (CI), of females were studied. Temperature ranged between 14°C and 20°C in the upper 10 m, whereas Chlorophyll-a varied between 3 and 14 mg m3. The horizontal current field (upper 20 m) showed 3 zones, a highly advective zone (offshore flow), an inertial zone (within the plume), and a retention zone (eastward-flow). Overimposed there was a residual current poleward (0.36 m s-1 on average). C. chilensis showed greater concentrations within the retention zone. FL, DW, CI and GI were negatively correlated to temperature, but not to chlorophyll. Abundance of copepodids and size of females were highly associated with components of the current field. Spatial distribution, growth and development of C. Chilensis in these conditions, are much dependent on temperature rather than food, due to the temporal and spatial variability of surface circulation.

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Aquatic Sciences Meeting, Albuquerque 2001

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