why is it that below a certain depth planktonic organisms leave behind
Phytoplankton drifting about below the surface of the water still carry out photosynthesis. This process can occur as long as enough light is available for the chlorophyll and other pigments to absorb. In the ocean, light can reach as far as 200m below the surface 25.hlorophyll is not the only photosynthetic pigment found in algae and phytoplankton. There are also carotenoids,and phycobilins (biliproteins). These accessory pigments are responsible for other organism colors, such as yellow, red, blue and brown.