Question: carbon dioxide is a limiting resource for most aquatic plants...
Carbon dioxide is a limiting resource for most aquatic plants, even though it can reach quite high concentrations in surface waters. How is that possible?
Plants deplete the water immediately surrounding their leaves, creating a low-CO2 boundary layer.
It's bound up in bicarbonate, which plants cannot use.
Lakes and oceans are too acidic for most aquatic plants to function.
Plants prefer to use bicarbonate for photosynthesis, so CO2 is not used.