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Volume 44 - Number 2 - 2009


Phytoplanktonic primary production modulated by coastal geomorphology in a highly dynamic environment of central Chile

Alvaro T. Palma1, Luis A. Henríquez1 and F. Patricio Ojeda1


1Center for Advanced Studies in Ecology and Biodiversity (CASEB) and Departamento de Ecología, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile




Coastal upwelling circulation has a regional fertilizing effect upon phytoplanktonic communities (i.e. enhancement of photosynthetic rates, increased biomass), but its influence at smaller spatial and temporal scales is less clear. At local scale (100's m) and under upwelling-favorable conditions, retention zones with higher primary production (PP) levels tend to occur at the lee or protected side of small headlands induced by the orientation, geometry, size and general geomorphology of these coastal formations. Here we quantified net and gross primary production (NPP and GPP), community respiration (CR) and biomass (Chl-a) of natural phytoplankton assemblages in coastal environments of central Chile. The main goal was to determine short-term patterns in PP and CR around two small peninsulas in central Chile where measurable differences in several environmental variables can be expected, and we hypothesize that differences will no longer occur under non-upwelling/relaxation conditions. Results indicate that NPP GPP and CR differ at local scale, and contrary to previous findings we found that weakening of upwelling-favorable winds can generate an opposite pattern to that observed under active upwelling periods, whereas the exposed site retains higher biomass and exhibits higher PP levels compared to the protected site. Our results highlight the importance of short-term variability in PP, CR and their coupling with the distribution and abundance of the quick-responding phytoplankton at local spatial scale


Key words: Nearshore oceanography, upwelling, phytoplanktonic biomass, carbon flux, coastal morphology



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