BIOLOGICAL NEW PRODUCTIVITY IN THE EASTERN EQUATORIAL PACIFIC: RESPONSES TO NUTRIENTS INPUT FROM COLOMBIAN PACIFIC RIVERS, COASTAL UPWELLING AND ATMOSPHERIC DUST

Understanding the carbon cycle and the climate system requires a deep knowledge of the nutrient balance and the mechanisms that control biological productivity in the Eastern Equatorial Pacific (EEP). We used two box models to explore the balance of nutrients and its biological productivity in terms of new production (NP) in a region in front of the mouth of the Rio San Juan (2.5 degrees N - 5.5 degrees N and 77.5 degrees W - 86.5 degrees W). A NP of similar to 215 mg C m(-2)day(-1) results from a model where the fluvial contribution is neglected; whereas a NP of similar to 227 mg C m(-2)day(-1), - equivalent to primary productivity (PP) of similar to 1.51 g C m(-2)day(-1)-, results from a model that includes fluvial contribution of nutrients. In our models it is evident that the flow of Fe and NO3 must change seasonally and with the rainfall regime that affects fluvial discharge. Iron supply controls NP independently of NO3 availability in the water column. In contrast to the south Equatorial Front, PP offshore the San Juan river increases due to the continental supply of nutrients.