Water Clarity
Scientists use a secchi disc to measure water clarity. Image courtesy Mike Land.
Water clarity is a measure of the amount of sunlight that can penetrate through the water. Clear water is indicative of a healthy Chesapeake Bay, though clarity will always fluctuate naturally depending on weather conditions.
How Is Water Clarity Important?
Clear water is critical to underwater bay grasses. The amount of light that reaches these underwater plants growing in the Chesapeake Bay's shallow waters is the single most important factor determining their growth and survival.
Fish also need clear water to see their food and avoid being eaten by predators.
What Causes Poor Water Clarity?
Poor water clarity is usually caused by a combination of:
How Do Scientists Measure Water Clarity?
Scientists use a device called a secchi disc to measure water clarity. A secchi is a round, black and white disc attached to a rope. The secchi disc is lowered into the water until it can no longer be seen. Then scientists note and measure the water line on the rope. The measurement, called the secchi depth, is the depth that sunlight is able to penetrate through the water.