Algae and phytoplankton are microscopic plants that grow and drift in the water column. They are an important food source for the zooplankton (microscopic animals), oysters, clams, mussels, and menhaden. Most of the animals living in the Chesapeake Bay and tidal tributaries feed directly on phytoplankton or their secondary products.
However, due to excessive phosphorus and nitrogen loading, the phytoplanktons’ food supply is unlimited causing them to grow and expand, resulting in large phytoplankton and algae blooms. This coupled with a massive reduction in the number of filter feeders that eat the phytoplankton—such as oysters and menhaden—indicate that the food web has been broken.
So what does phytoplankton have to do with chlorophyll? Chlorophyll is a green pigment that is found in plants, such as phytoplankton and algae. Chlorophyll converts energy that it absorbs from the sun to carbon dioxide to carbohydrates, which is the plants’ food source.