16 The Peruvian Coastal Upwelling System
J. TARAZONA and W. ARNTZ
16.1 Introduction
The Peruvian coastal upwelling ecosystem is part of an upwelling area that
extends between 4°S and about 40°S along the western coast of South
America (Guillen 1983), with high productivity originating from equatorial upwelling south of the Galapagos Islands. Peruvian coastal upwelling
is peculiar because winds sustain the upwelling process throughout the
year (Zuta and Guillen 1970) and the El Nino-Southern Oscillation (ENSO)
cycle induces distinct interannual ecosystem variability. The coastal
upwelling system, which hardly comprises 0.02% of the total ocean surface, is of great significance because it determines the enormous productivity of Peruvian coastal waters, representing almost 20% of the world's
landings of industrial fish.
16.2 Environmental Characteristics
16.2.1 Currents and Winds
The complex current system off Peru is associated with the Equatorial
Current system (Fig. 16.1A). The superficial currents flow predominantly
northward. The Peru (or Humboldt) Coastal Current (4-15cm s- 1 ) is
closest to the coast and confined to the uppermost 200m depth, transporting cold water (14-16 °C} in summer. The Peru Oceanic Current (down to
700 m depth) reaches higher velocities than the Peru Coastal Current.
Between these currents the weak, irregular southward flow of the Peru
(or Humboldt) Subsurface Countercurrent is usually subsuperficial but
occasionally reaches the surface. The subsurface currents constitute an
extension of the Equatorial Undercurrent. The principal current, the PeruEcological Studies, Vol. 144
U. Seeliger and B. Kjerfve (eds.)
Coastal Marine Ecosystems of Latin America
©Springer-Verlag Berlin Heidelberg 2001
J. TARAZONA and W. ARNTZ
16.1 Introduction
The Peruvian coastal upwelling ecosystem is part of an upwelling area that
extends between 4°S and about 40°S along the western coast of South
America (Guillen 1983), with high productivity originating from equatorial upwelling south of the Galapagos Islands. Peruvian coastal upwelling
is peculiar because winds sustain the upwelling process throughout the
year (Zuta and Guillen 1970) and the El Nino-Southern Oscillation (ENSO)
cycle induces distinct interannual ecosystem variability. The coastal
upwelling system, which hardly comprises 0.02% of the total ocean surface, is of great significance because it determines the enormous productivity of Peruvian coastal waters, representing almost 20% of the world's
landings of industrial fish.
16.2 Environmental Characteristics
16.2.1 Currents and Winds
The complex current system off Peru is associated with the Equatorial
Current system (Fig. 16.1A). The superficial currents flow predominantly
northward. The Peru (or Humboldt) Coastal Current (4-15cm s- 1 ) is
closest to the coast and confined to the uppermost 200m depth, transporting cold water (14-16 °C} in summer. The Peru Oceanic Current (down to
700 m depth) reaches higher velocities than the Peru Coastal Current.
Between these currents the weak, irregular southward flow of the Peru
(or Humboldt) Subsurface Countercurrent is usually subsuperficial but
occasionally reaches the surface. The subsurface currents constitute an
extension of the Equatorial Undercurrent. The principal current, the PeruEcological Studies, Vol. 144
U. Seeliger and B. Kjerfve (eds.)
Coastal Marine Ecosystems of Latin America
©Springer-Verlag Berlin Heidelberg 2001