Increased phytoplankton blooms are a symptom of ecosystem degradation in the Coastal Bays

The seagrass chlorophyll threshold was met in Isle of Wight, Sinepuxent and Chincoteague Bays; while the St. Martin River and upper Newport Bay failed.  Despite many inshore and river areas failing nutrient thresholds, chlorophyll values were generally low in the open bays. 

Three-year (2001-2003) seagrass growing season chlorophyll a concentration medians were calculated for each monitoring station and compared to established thresholds. Results of these analyses are presented in the chlorophyll a status map.

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 What is Chlorophyll and how much is too much?

All plants contain chlorophyll - a green pigmented material essential for photosynthesis.  Measuring the amount of chlorophyll in a water sample gives us an estimate of the quantity of phytoplankton (microscopic plants also know as 'algae') living in the water.  Among other valuable functions, algae are important food for fish and shellfish.  When nutrient loading increases and algae blooms result, many problems may occur, including fish kills due to low dissolved oxygen and seagrass declines due to decreased light availability.

Chlorophyll a is a type of chlorophyll commonly found in phytoplankton, and has been chosen as an indicator to determine the health of the bays. The Maryland Coastal Bays Program has adopted a 15 µg/l concentration of chlorophyll a as a threshold of poor water quality in open bays. The program has also set a threshold of 50 µg/l chlorophyll a in upper tributaries and prongs. These thresholds were derived from seagrass habitat requirements.  

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