In an aquatic ecosystem the algae and phytoplankton are responsible for primary productivity. All BUT ONE factor usually influences the primary productivity of a marine ecosystem. That is?

In a marine ecosystem, primary productivity is influenced by factors such as light availability, nutrient concentration, and temperature. However, the salinity of the water typically does not directly influence primary productivity in the same way. While extreme salinity can affect the types of organisms present, it is not a primary determinant of productivity like the other factors mentioned.