Aquatic Grasses in Delaware’s Inland Bays

Aquatic Grasses in Delaware’s Inland Bays Estuary or Canary in the Coal Mine?

Years ago Coal miners used to carry a canary into the coal mines with them- Why?

Ans: If the mine had high levels of methane or low levels of oxygen the canary would drop dead alerting the miners to quickly evacuate the mine.

Note- since the Inland Bays Estuary Pollution Control Strategy was committed to by the State of Delaware in 2008 the Total Daily Maximum Loads for Nitrogen, Phosphorous and Bacteria have not been met. The canary is dead or gasping for breath!

Ok- so how does that relate to the poor water quality in Delaware’s Inland Bays Estuary?

Ans: substitute aquatic grasses for the canary, i.e. – “eel grass”. Chincoteague Bay in neighboring Virginia has acres of eel grass as does Barnagut Bay in New Jersey. Our Inland Bays have none despite frequent attempts to propagate seedlings from Chincoteague Bay.


Why is eel grass so important?

  • Eelgrass is one of the most important and vital habitats for a wide range of fish and wildlife, including flounder,bay scallops, and crabs. At the base of the food chain, many species of commercially valuable fish feed on, or take shelter in, these beds during some stage in their life cycle. Eelgrass beds filter excess nutrients out of the water and help prevent shoreline flooding and erosion by stabilizing sediment and buffering wave action. Because it requires specific amounts of light and clean water, the presence of eelgrass is an indicator of healthy water quality.
  • Eelgrass habitats are among the most productive and biologically diverse ecosystems on the planet. Living and dead plant material, including leaves, roots and rhizomes, has many valuable ecological functions such as stabilizing seafloor sediments and shorelines, cleaning coastal waters, providing habitat for a diversity of flora and fauna, and supporting the foundation of the detrital food web.

What causes our Estuary to not have any eelgrass?

  • How do Human Activities Impact Eelgrass? • Nutrient Pollution Increased nutrient-loading (from lawn fertilizers, car emissions, detergents, sewage, etc.) causes excessive epiphyte growth on eelgrass blades and algae blooms in the water column, blocking out light. • Dredging Not only are the plants removed, but the entire physical, biological and chemical structure of the ecosystem is changed. Plumes of loose silt bury plants, smother animals, and reduce light penetration away from the dredge site. • Logging Clear-cutting, logging roads, and steep slope failures in watersheds can increase sedimentation and turbidity in estuaries below. This reduces the ability of light to penetrate the water and reach the eelgrass beds. • Shoreline or Over-water Construction Changes in the shoreline that alter the absorption of wave energy may erode the bottom and also increase turbidity. Structures built over the water prevent eelgrass from getting enough light to grow. • Spilled Oil Direct contact with oil causes eelgrass plants to lose their leaves. • Herbicides Runoff of herbicides used on coastal land can kill or damage eelgrass.
  • Large concentration of algae (caused by nutrient pollution) shield the grasses from sunlight preventing them from producing dissolved oxygen and eventually killing the grasses.

Why are Aquatic grasses important to the Inland bays Estuary?

  • They provide a source of dissolved oxygen for a healthy aquaculture that will support robust growth of Finfish and Shell Fish
  • They provide a healthy shelter for juvenile fish and spawning adult fish
  • Their root systems will stabilize the bottom and shore line of our estuary
  • An abundance of grasses will minimize the impact of storm surge and wave action

The Inland Bays Foundation has formulated a 2017 Action Plan to address potential low cost (to the tax payer) solutions to preventing further degradation of our waters:

  • Agriculture- fully fund the USDA sponsored “Cover Crop” program
  • Remove failed or failing septics through the Public Sewer Program
  • Establish Municipal Storm Water (MS-4) projects in the Urban Areas along route one

Visit the Foundation web site at: if you would like to see the details or be a part of making our Inland Bays “Fishable and Swimmable” again. Keep the canary alive and breathing.