Extraordinary Eelgrass – Fast Facts

Gliding your kayak over a bed of bright green eelgrass in the intertidal zone can be pure bliss, the waving blades a picture of serene beauty beneath your hull. Yet this plant holds secrets beneath the surface… Did you know that it has two methods of propagation? Or that it converts atmospheric carbon into oxygen and provides a home — at some point — to many of the ocean’s creatures? Read on for more fascinating facts about this very special marine plant.

Eelgrass – Fast Facts

• Eelgrass is a perennial flowering plant, or angiosperm. It is not a seaweed.
• Eelgrass is found on every continent except Antarctica. It even lives in the cold waters of James Bay!
• There are at least 16 different species of eelgrass worldwide. One species — Zostera marina — is found here in BC.
• Eelgrass is also known as seagrass or seawrack. Eelgrass beds are sometimes called forests, meadows, or underwater lawns!
• Eelgrass grows in salty or brackish waters along shallow shorelines, bays, inlets and river estuaries. It loves soft mud seafloors, intertidal zones and tidal pools. You won’t find eelgrass on a storm-pounded shoreline!
• Eelgrass blades grow up to 20 millimetres wide and 1.5 metres long.
• The individual plants in an eelgrass bed are connected by a network of underground stems, or rhizomes, that grow horizontally under the seafloor and send new shoots up from the rootstock. (View an illustration of eelgrass rootstock.)
• Eelgrass can propagate to new areas via underwater pollination. Each plant grows male and female flowers, which together produce seeds that float away on currents to colonize new locales. (View an image of eelgrass flowering process.)
• Eelgrass beds play a key role in stabilizing coastlines: their extensive root systems fix sediment in place, and their thick forests moderate waves and currents to reduce shoreline erosion.
• Eelgrass beds act as massive carbon sinks (the plants turn carbon dioxide into oxygen via photosynthesis). A Swedish study found that one hectare of eelgrass can sequester almost 100 tons of carbon and 500 kilograms of nitrogen.
• Eelgrass blades provide a home to over 100 species of microscopic algae — which serve as food for crabs, snails and shrimp; which in turn nourish small or young fish; which in turn are eaten by sea and shore birds.
• It is estimated that 80 per cent of fish and invertebrates use or shelter in eelgrass beds during at least part of their lifespans.
• Brandt Geese are one of few animals that eat eelgrass as their primary food source.
• Prior to the 1930s, eelgrass was harvested by humans and used to insulate and sound-proof homes; stuff pillows, mattresses and furniture; thatch roofs; pack boxes; and make fertilizer. Eelgrass is no longer harvested commercially.
• Eelgrass is susceptible to damage by many human activities. Boats on anchor can raze beds in the vicinity of a dragging chain, log booms rob beds of sunlight and bury them in bark peelings, water pollution feeds algae blooms that coat grass blades and hamper photosynthesis… And, yes, dragging your kayak over eelgrass, or walking on a bed, causes damage.
• Eelgrass is being replanted (one plant at a time) by volunteer groups on Vancouver Island, in the Gulf Islands, in Howe Sound and along the Sunshine Coast.

Sources

Most of the facts in this post were drawn from the article “Eelgrass: Playing a Vital Role on British Columbia’s Coast” by Marianne Scott, published in the Spring 2022 issue of British Columbia Magazine.

Other facts were drawn from the brochure Protecting Eelgrass, published in 2016 by the Seagrass Conservation Working Group, TD Friends of the Environment Foundation, SeaChange Marine Conservation Society and Parks Canada, and available on the Islands Trust website.

Header image credit: Hakai Magazine.