The researchers studied five underwater plants to see how they use light for photosynthesis. They found that different plants have different light needs. Some plants can live in deeper water because they have stalks that don't do photosynthesis. Vallisneria needs less light, while Myriophyllum and Ceratophyllum like lots of light. Potamogeton and Hydrilla are in the middle. High light can slow down photosynthesis in all plants. Overall, each plant has its own way of using light to grow underwater.