Eelgrass Tide Pools

There have been some really good low tides in the late afternoon this week and I’ve been able to get out on the sand flats and poke around in the eelgrass tide pools at Miracle Beach Provincial Park on Vancouver Island, British Columbia. I love exploring tide pools because it doesn’t matter how often you do it, you’re sure to find something new. There is always something in the eelgrass!

Eelgrass (Zostera marina)
Eelgrass (Zostera marina) is a marine vascular plant that produces flowers and seeds.

Eelgrass is not a Seaweed

Despite looking superficially like seaweed, eelgrass (Zostera marina) is a vascular flowering plant that has roots (rhizomes), stems and leaves. Air spaces called lacunae in leaves and rhizomes provide buoyancy. Eelgrass reproduces asexually by sending up shoots from the spreading rhizomes. It also reproduces sexually by producing tiny, inconspicuous flowers. These flowers are fertilized by pollen which is transported in the water.

Eelgrass (Zostera marina)
Seeds of Eelgrass (Zostera marina) are produced in capsules in a sheath.

Seeds of Eelgrass

While squatting down in the shallow water looking through the blades of eelgrass I found something that I had never seen before. I didn’t find the flowers of the plant, but I did find what appear to be the remains of seedcases. Apparently the gelatinous capsule eventually ruptures and the seeds fall to the bottom of the eelgrass bed where they begin growing. Once I knew what to look for I found several other seedcases in the eelgrass tide pools—very cool!

Eelgrass (Zostera marina)
Gelatinous capsules cover the seeds of Eelgrass (Zostera marina).

Important Eelgrass Tide Pool Habitat

Eelgrass plays an important role in the marine ecosystem. The rhizomes serve to stabilize the sand flats and reduce the impact of wave action. Tide pool eelgrass also provides valuable habitat for hundreds of invertebrates and 80 species of fish, and 75 species of birds. In British Columbia, eelgrass beds are particularly important as shelter and food for growing juvenile salmon (Oncorhynchus spp.), spawning habitat for Pacific herring (Clupea harengus), food and growth of Dungeness crabs (Cancer magister), and food for brant (Branta barnicla), and many millions of waterfowl that migrate and spend the winter along the Pacific Coast. – The Pacific Wildlife Foundation

I was pleased to find these seed capsules this week. Hopefully they are a sign that the eelgrass beds at Miracle Beach will continue to grow, providing a sheltered place for numerous organisms to call home and a wonderful place for people to explore.

Further reading about Eelgrass: