System-wide Monitoring Program

Chlorophyll

Aquatic plants can be divided into two categories: macrophytes and phytoplankton. Macrophytes are multicelled plants visible to the eye. This category includes both macroalgae (seaweeds) and flowering plants (eel grass). Phytoplankton (e.g., diatoms) are microscopic one-celled plants that float in abundant numbers in the water column, sometimes grouped in colonies. For example, a liter of seawater might contain one million diatoms. Phytoplankton are extremely important as the basis of the estuarine aquatic food web. They are eaten by zooplankton (microscopic animals) and small fish, which in turn are eaten by larger creatures. Consequently, the abundance of animals in an estuary often depends on the amount of primary productivity (conversion of light energy to plant biomass) taking place.

Measuring the amount of chlorophyll (photosynthetic pigments) in the water gives us a useful index of phytoplankton density, and this reflects the amount of primary productivity occurring. Chlorophyll levels can be used to compare primary productivity within a single estuary or between two or more estuaries.

Biological Monitoring

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