Potential utilization of temperature in estimating primary production from remote sensing data in coastal and estuarine waters

Abstract

Two biological data sets, collected in the estuary and the Gulf of St Lawrence (Canada), were analysed to examine the contribution of temperature to mesoscale variations in primary production. In order to take into account the wide range of hydrodynamical conditions, the data were temporally and spatially partitioned. Temperature was found to explain a significant fraction of the spatial variations in primary production only in regions where nutrient concentrations were low. In these regions, an inverse relationship was observed between temperature and nitrate concentrations which was attributed to an effect of upwelling, while a positive relationship was observed between nitrate concentration and the chlorophyll-specific light utilization efficiency (ψ'). This study leads to the conclusion that in estuarine and coastal waters where nutrient concentrations are low, the inclusion of spatial variations in surface temperature (reflecting the influence of nitrate on ψ') can significantly improve the predictive power of models used to estimate primary production from remote sensing. A new primary production model including surface temperature is thus proposed for future use with the LIDAR (LIght Detection And Ranging), one of the most reliable remote sensing techniques for surveying estuarine and coastal waters.