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"Fish and shellfish which depend on eelgrass for all or part of their life cycle account for a multimillion dollar industry in Washington..."  
Port Townsend Marine Science Center.

Eelgrass Facts

  • Eelgrass is not a seaweed; it is a blooming underwater grass which spreads by rhizomes or roots.
  • Eelgrass meadows build up in the spring and summer, then decay in the fall and winter.
  • Eelgrass blades can grow up to 3 feet long.
  • Zone: shallow subtidal.
  • Habitat: muddy, sandy bottoms.
  • Damage to eelgrass affects whole populations of fish, including threatened salmon, waterfowl, shellfish, and other animals, as well as the stability of our shorelines.
Each Blade is a Food Factory  
Each blade of eelgrass is a small food factory. Diatoms, bacteria, and detritus (decaying plant and animal matter) gathers on eelgrass leaves. This detritus provides food for many invertebrates; isopods, amphipods, polychaete worms, brittle stars, and some clams. The large number of invertebrates present make eelgrass beds rich feeding areas for fish and marine birds.

As eelgrass dies, bacteria and fungi feed on the dead leaves, breaking them down into tiny bits. These particles of plant material provide vital nutrients for the nearshore food web.

Eelgrass: Erosion Control

Eelgrass meadows cushion the impact of waves and currents, preventing erosion. Eelgrass roots weave sediments in place. This protection helps preserve the highly productive bacteria in the sediments which nourish large amounts of invertebrates.

During low tides, eelgrass shelters small animals and plants from extreme temperatures. On tideflats, eelgrass beds hold moisture like a sponge, offering additional protection for small creatures.

What's In Eelgrass?

Many animals use eelgrass beds for nursery areas, others swim or walk among the leaves, or burrow in the sediments. Within eelgrass meadows, there is food and shelter for a wide variety of sea anemones, marine worms, snails, limpets, crabs, birds, and fish.

  • Salmon Shelter
    Eelgrass shelters juvenile salmon and important salmon snacks such as harpacticoid copepods.
  • Crab Camp
    The Dungeness crab often moves into eelgrass meadows to molt in the spring. Other crabs found in eelgrass include the red crab, the graceful crab, the spider crab (Pugettia gracilis), and the helmet crab.
    Herring eggs deposited on eelgrass. Photo by Dan Penttila, WDFW.
  • Homes For Herring
    Eelgrass forms a hiding place for herring eggs and young. Herring is a major food source for salmon, seabirds, seals, and other marine mammals.
  • Nudibranch Niche
    The opalescent nudibranch swims among eelgrass blades feeding on invertebrates and their eggs. It sports iridescent plumes that are in fact gills.
  • Grub for Gunnels
    Gunnels are often confused with eels. Their top fin is long and spiny. Gunnels swim in shallow water among eelgrass blades, feeding on crustaceans and mollusks.
  • A Port for Pipefish
    The bay pipefish grows to about 13 inches long and is related to the seahorse. Males incubate young in a brood patch. They eat small crustaceans within eelgrass meadows.

    The End Of Eelgrass

    • Dredging destroys eelgrass and eliminates food and shelter for an entire ecosystem.
    • Structures such as docks can prevent eelgrass from getting enough light to grow.
    Herring egg photo by Dan Penttila, Washington Department of Fish and Wildlife.

    Related Links

    All About Eelgrass, Port Townsend Marine Science Center.
    What's so essential about eelgrass? Read all about it. 

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