Well, in a way it is true, as, chloroplasts are the reason why plants photosynthesize. So, with the photosynthesis, it releases oxygen, which is the power generator for life on Earth, as we breathe in oxygen.
They ensure they leave the system and they also ensure that people get the nutrients they need.
In summer, the temperature of Vermont is lower than that in Florida. And the temperature is an important factor influences the gas dissolving ability. When temperature increases, the ability will decrease. So there is more dissolved oxygen in Vermont's lake.