Ria Formosa was shown to be globally in a good trophic condition. Productivity is higher in the shallow areas near mainland because they have higher residence times and more light availability. The primary source of nutrients to system is the sea. WWTP loads have small and local impact on the system. Removal of nutrients in WWTP’s would have no consequence for the trophic level in the lagoon.

The reduction of nitrate from agriculture will not be an important factor in this system. Ria Formosa has a small, non-permanent fresh water flow with a load several orders of magnitude lower than the nitrate received from the sea.