The net annual primary productivity of a particular wetland ecosystem is found to be 6,000 kcal/m2/yr. If respiration by the aquatic producers is 10,000 kcal/m2/yr, what is the gross annual primary productivity for this ecosystem, in kcal/m2/yr? 4,000 kcal/m2/yr 6,000 kcal/m2/yr 10,000 kcal/m2/yr 16,000 kcal/m2/yr