Spatial re-organizations in the coastal Humboldt Current ecosystem under oceanic climate forcing: portraying contrasted ecological scenarios

One of the main sources of the climatic variability in the Humboldt Current system consists of the arrival of the coastal Kelvin waves, themselves being forced at the equator by the equatorial Kelvin waves (Pizarro et al., 2002). The equatorial Kelvin waves are generated along the Equator, in the mid Pacific (180ºW) by an anomaly of the wind flow and then propagate Eastwards across the oceanic basin. According to the kind of wind anomaly (under-pressure or over-pressure), the equatorial Kelvin wave may be of downwelling or upwelling type. When these waves hit the South-American continent, a portion of their energy is transmitted along the coast as 'coastal trapped ' or 'coastal Kelvin ' waves. Because these coastal waves introduce background energy for the turbulent flow in the coastal ecosystem, they are likely to produce deep impacts on a variety of components of the coastal ecosystem. On a physical point of view, a downwelling wave produces an intrusion of oceanic poor and warm waters in the coastal ecosystem and then a warm scenario (El Niño like scenario, Pizarro et al., 2002). On the contrary, an upwelling wave favours cold and rich water resurgence and then the extension of the coastal water domain (a cold, La Niña like scenario). In that context, the aims of this paper are (1) to describe the spatial re-organisations of living organisms in the Humboldt coastal ecosystem under the effect of the arrival of the costal Kelvin waves, (2) to formulat