Using the data taken from fixed station observations, we can conclude from our speculative interpretations of the four periods, that the causes of temporal variations are quite complex. Some causes may originate locally, such as the small nutrient pulses. Others causes are regional: therefore our interpretation of observed nutrient concentration increases and type should not be restricted to only terrigeneous inputs or sediment composition at a local scale. Changing from a local to regional scale depends on the duration and geographical extension of the meteorological event. One illustration of the duration effect may be the SRP exhaustion following a long period of rain, as was observed in the Ouinné River by Tenório et al. (2005). In fact, during their study, river SRP concentration dropped from 0.113 to 0.050 μM in 1-month.