Chlorophyll a

Chlorophyll is the green pigment that allows plants (including algae) to convert sunlight into organic compounds during photosynthesis. Of the several kinds of chlorophyll, chlorophyll a is the predominant type found in algae. High amounts of chlorophyll a in the Bay's waters are a primary indicator of nutrient pollution because excess nutrients fuel the growth of algae.

Why is it important to measure chlorophyll a?

Scientists use chlorophyll a to measure the amount of algae present in the Bay. The Bay needs the right amount of algae to maintain a balanced food web. Too much algae can cause large-scale algae blooms that:

• Block sunlight from reaching underwater bay grasses, reducing available habitat for Bay life.
• Usually consist of a single species of algae, typically one that is not desirable to fish and other algae-consuming organisms.
• Eventually sink to the bottom and decay in a process that depletes deeper waters of oxygen.
• Can become harmful algae blooms that have adverse impacts on aquatic life and human recreation (including swimming, boating and fishing).

Lower algae levels promote better water quality, more available habitat and fewer harmful bloom effects. Having the right levels of chlorophyll a generally means there is enough algae to fuel the food web.