Chlorophyll-a

Chlorophyll-a – A plant pigment whose concentration in water is used to estimate the amount of phytoplankton or algae.

Plants and algae use this pigment to trap the energy from the sun so they can grow. Chlorophyll a is measured in micrograms per liter ( µ g/l) units. Micrograms per liter is micrograms of chlorophyll a per liter of water. In estuaries, chlorophyll a measurements can range from 1 µ g/L to higher than 20 µ g/L.
Scientists measure chlorophyll a in the lab by separating the chlorophyll a from the
algae in the water.

Why is Chlorophyll a Important?

Chlorophyll a tells us how much algae is in the water. Algae are small plant-like organisms that float in the water and use the sunlight to grow. Too much algae can cause problems. As algae die, bacteria eat them. This can lower the oxygen in the water since bacteria need oxygen to grow. If there is no oxygen, some of the animals and plants in the water can die!
Some algae are poisonous to fish, shellfish, and even humans.