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Scaling relationships (where body size features as the independent variable) and power-law distributions are commonly reported in ecological systems. In this review we analyze scaling relationships related to energy acquisition and transformation and power-laws related to fluctuations in numbers. Our aim is to show how individual level attributes can help to explain and predict patterns at the level of populations that can propagate at upper levels of organization. We review similar relationships also appearing in the analysis of aquatic ecosystems (i.e. the biomass spectra) in the context of ecological invariant relationships (i.e. independent of size) such as the 'energetic equivalence rule' and the 'linear biomass hypothesis'. We also discuss some power-law distributions emerging in the analysis of numbers and fluctuations in ecological attributes as they point to regularities that are yet to be integrated with traditional scaling relationships and which we foresee as an exciting area of future research.

The hlgh biological productivity of the Hurnboldt Current System (HCS) off Chile supports an annual fish catch of over 7 mill~on t. The area is also important biogeochemically, because the outgassing of recently upwelled water is modulated by contrasting degrees of biolopcal activity. However, very few field measurements of primary production and planktonic respiration have been undertaken within the Eastern Boundary Current (EBC) system off Chile. In this study an estimate of primary production (PP) and surface planktonic commun~ty respiration is presented from several research cruises in the HCS and adjacent oceanlc areas. The highest production levels were found near the coast correlating closely with known upwelling areas. Both gross primary production (GPP) and community respiration (CR) showed important spatial and temporal fluctuations. The highest water column integrated GPP was measured in the southern and central fishing area (19.9 g C m-2 d-l) and off the Antofagasta upwelling ecosystem (9.3 g C m-' d-'). The range of GPP agrees well with values reported for Peni (0.05 to ll

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Abstract. During the 1997-98 E1 Nifio event, the temperature and oxygen contents of the coastal waters off northern Chile were noticeably higher than during non-E1 Nifio conditions, but phytoplankton and zooplankton biomasses were not dramatically altered. In contrast, the herbivorous copepod Calanus chilensis, which showed a limited tolerance to low-oxygen conditions, exhibited greater abundances, higher growth rates, and a significant reduction in adult body size. These results indicate a positive effect of the changes in oceanographic conditions due to E1 Nifio on zooplankton growth and production, and provide evidence for lack of food limitation on secondary production in the coastal region during this period.