Answer:
Phytoplankton.
Step-by-step explanation:
This is because in the mangrove swap, phytoplankton is a green plants that have green pigment called chlorophyll uses light energy from the sun with carbondioxide and water to produce carbohydrates. Phytoplankton is a primary producer because it manufacture it food through the process of photosynthesis and it is the source of flow of energy in the habitat.