Bujan, S. ORSTOM - Laboratoire d'Oceanographie et de Biogeochimie de Marseille, (687).26.43.26
Grenz, C. CNRS - Laboratoire d'Oceanographie et de Biogeochimie, Marseille, firstname.lastname@example.org
Fichez, R. ORSTOM, email@example.com
Douillet, P. ORSTOM, firstname.lastname@example.org
CONTRIBUTION OF OCCASIONAL FRESHWATER INPUTS ON A COASTAL SUBTROPICAL ECOSYSTEM. IMPACT ON NUTRIENTS AND PHYTOPLANKTON BIOMASS DESCRIBED THROUGH A BIOGEOCHEMICAL SIMULATION MODEL
Extensive field studies have been carried out over the 2000 km2 of South West lagoon of New Caledonia surrounding the city of Nouméa for the past 20 years. An analysis suggests that it would be suitable to develop an approach to gain (i) a more synthetic view (ii) predictive capacity regarding lagoon ecosystem functioning. The present work uses a coupled modelling approach, which combines results produced from a 3D hydrodynamic model with a set of mathematical equations describing major biogeochemical processes.
Average residence times proved to be no more than 10.9 days for the lagoon as a whole. The coastal system is subject to occasional fresh water inputs linked to tropical depressions or cyclones during the period December to March. Major efforts have been devoted toward proper assessment of carbon and nutrient cycling, chlorophyll a being mostly used to rapidly check for the validity of model outputs. Terrigeneous and anthropogenic influences were significant in areas protected from wind exposition but only during short periods of heavy rainfall. Biogeochemical processes at benthic boundary layer are dominated by bacterial and microphytobenthic activity.
Tropical climatic events and long term simulations over decades will be discussed in the context of eutrophication of tropical lagoons.
SS52 CS04 CS36 : Modelling a coastal subtropical ecosystem
Day: Thursday, Feb. 4
Location: Sweeney Center