Nutrients

Nutrient levels exceed seagrass growing thresholds, especially phosphorus.

The greatest concern for the bays’ health is eutrophication resulting from high nutrient loading, especially phosphorous. Nitrogen levels exceed seagrass requirements mainly in the tributaries as well as Assawoman Bay and northern Chincoteague Bay. Ninety-nine percent of sites do not meet the seagrass phosphorus threshold. Stricter requirements were established in 2016 to address this problem, by limiting the amount of phosphorous that can be applied to fields. High soil phosphorus is typically found on farms that have used manure or poultry litter as a crop nutrient over many years. This practice will be limited under the new requirements, but it will take time for reductions to be seen in bay phosphorous concentrations.

Previous year assessments

• 2004-2007 Total Nitrogen, Total Phosphorus
• 2001-2003 Total Nitrogen, Total Phosphorus
• 1999-2001 Total Nitrogen, Total Phosphorus

Nutrient levels show some improvements

While most stations in the southern Coastal Bays met seagrass chlorophyll threshold, many sites failed one or both nutrients. Trend analyses indicate nutrients are exhibiting improving conditions (especially below the Ocean City Inlet) but concentrations of nitrate may be on the rise in some areas.

For More information:

Ecosystem Health Assessment 2007-2013 –Nutrient Conditions, Chapter 4.1 [NEED LINK]