An application of an NPZ model to a coastal upwelling ecosystem in the Yucatan Peninsula, Mexico

MARINA, TOMÁS IGNACIO; HERRERA-SILVEIRA, JORGE ALFREDO; MEDINA-GÓMEZ, ISRAEL

Congreso; 22nd Biennial Conference of the Coastal and Estuarine Research Federation; 2013

The current study represents the first attempt to address the phytoplankton responses toa coastal upwelling event in the north-east Yucatan Peninsula (Mexico) under a dynamic model approach. The aim of this study is to evaluate the applicability of a simple NPZ model (nutrients-phytoplankton-zooplankton) to describe temporal changes in nutrients and plankton in the coastal upwelling ecosystem of Cape Catoche (NE Yucatan). An existent dynamic and compartmentalized NPZ model was modified and applied to our study site. Calibration of the model was performed both by using information about plankton behavior in upwelling-influenced pelagic ecosystems reported in the literature and by including observational data collected during a strong upwelling event (April-September) in the study site. Simulation results showed that slight changes in the velocity of upwelling induce a twofold increase in phytoplankton biomass, although only a relatively reduced increasein zooplankton biomass. Lowering in water temperature (-30% less) led to a decrease in phytoplankton growth rate and thus, a 13% reduction of phytoplankton biomass. On the other hand, phytoplankton biomass increased (19%) as PAR values got higher (30%). Sensitivity analysis suggested the model is particularly affected by phytoplankton growth rate and mortality rate, as well as by zooplankton maximum ingestion rate. In the Yucatan Peninsula the utilization of this type of ecological models is nonexistent and should be adopted as an alternative study tool.