Consider the Eelgrass

Consider the Eelgrass

Stella Wenstob | Fjord contributor

The mud squelches and the morning mist hangs heavy over the low tide. The beach beckons with its early riser buzz. Today’s low tide story is about eelgrass — a green plant that inhabits the Pacific intertidal from Baja to Alaska and makes up some of the most important estuarine environments.

Zostera marina as the biologists call it is one species of genus of sea grasses that exist in various forms worldwide. It consists of a thin (0.4 inch) grass-like frond, which can grow to lengths of 2-5 feet. Unlike other so called ‘seaweeds,’ eelgrass has a true root system (rhizomes), which anchors the plant and provides a path for nutrients that it extracts from the muddy or sandy substrate and also serves to secure its home beach against erosion. Like the land based strawberry plant or clover, eelgrass reproduces through the branching out of this rhizome system. Additionally, eelgrass is a true flowering plant and also reproduces with the production of small, buoyant seeds that disperse great distances in the water.

Eelgrass typically grows in a sandy-muddy sediment in the low-tide of semi-protected beaches. The depth varies, it begins at the tidal section of the beach— low enough to avoid the arid, midday tides of the summer —and only so deep into the sub-tidal zone as its photosynthetic fronds can tolerate (like many land plants, it does not like the shade).

According to recent genomic research (Olsen et. al 2016), eelgrass' evolutionary ancestor was a land plant that acclimatized to the salty ocean environment.

Eelgrass has specific adaptations, called "osmoregulation," that allow it to survive in the see-saw salt-levels of an estuarine environment- where the tide rises and falls exposing the grass to the air and also varying amounts of fresh and salt-water.

First Nations peoples up and down the Pacific coast utilized eel grass as a food source. The rhizomes were roasted in pit-cooks to flavor meat such as deer, porpoise and seal. It was dried and eaten in the winter. Northern tribes had special feasts for the eelgrass where the entire plant was eaten.

Eelgrass is also an important spawning place for herring— many First Nations groups valued the roe collected on the fronds of the eelgrass. As eelgrass beds act as an key nursery for so many marine species, including many species of financially important fish (such as salmon, cod and herring), they are protected in Washington, Oregon, California as well as in British Columbia. There are many efforts underway to restore eelgrass beds that are under threat due to human activity, such as pollution and development that destroys beds (by creating shade or actually digging up the plants). Although eelgrass beds are important environs both environmentally and financially their protection at the expense of shellfish farmers is a contentious subject. Recent research has shown that although there have been reductions in eelgrass beds, it is hard to track what specifically has led to this, also revitalization efforts are unpredictable at best (Shelton et al. 2017). Of course the beds need to be supported, but a balanced and educated view needs to be taken when imposing restrictions.

Don your gumboots and explore the low-tide lawn. Not only does the rhizome root system stabilize the beach sediment, the nutrients it fixes from the mud attracts and feeds many algae and sea animals. When the tide is in, the grass provides protection from prying eyes for schools of fish, crabs, nudibranchs, and many types of sea invertebrates. At an early low summer tide, you may find the telltale lump in the sand that indicates a partly burrowed Dungeness crab hiding in the eelgrass. Many species of crabs come into the shallows to hide in the eelgrass to molt.

Eelgrass roof in Denmark

The eelgrass evolutionary ancestor was a land plant that acclimatized to the salty ocean environment.

Put on a snorkel and a wetsuit and pretend you are in the tropics or a mangrove swamp for a biodiverse snorkeling adventure at mid-tide. Join the Great Blue Herons and Belted Kingfishers in their madcap, mid-tide feed. Marvel at schools of shiners or perch meandering through the eelgrass.

Get surprised by nearly invisible Sand Soles who camouflage on the beach floor, with two eyes facing up at you. Keep your eyes peeled for shrimp and arthropods. You could try to paddle your kayak or row through an eelgrass bed at mid-tide, but time it right, as your paddle or oar can get tangled in the grass and disturb the ecosystem.

The grass is GREENER in the intertidal zone.

FAR FLUNG FACTS

1. In Denmark eelgrass was used historically for thatching roofs.

Heritage home in Denmark with eelgrass roof.

2. In the Netherlands eelgrass was once the main building material of the dikes.

3. Dried eelgrass was used in Europe for stuffing mattresses and cushions.

4. The Seri Native Americans of Sonora, Mexico, were reported to have harvested the seeds of eelgrass for food, which is said to be the only grain from the sea ever used as a human food source.

5. More recently, in Germany, designer Carolin Peitsch uses eelgrass to create stools. She makes the seat out of a plywood formed from a special combination of resin and eelgrass that has washed up on the shore of the North Sea.

Eelgrass stool

So next time you see a bed of eelgrass chances are you will look at it a little different. It's not just a sea of unruly seaweeds, it's an important habitat as well as a historically useful resource.