Sea Otters’ Destructive Digging Habit Is Boosting Ocean Health

Feb 04, 2022by Olivia - F&F

Canadian researchers have discovered that sea otters’ seemingly-destructive digging is actually helping to combat climate change and shoreline erosion — keep on reading to find out how! 

Sea Otters Are Helping Eelgrass Meadows… By Digging Them Up

Although they’re one of the cutest animals on the planet, sea otters have a pesky habit of digging holes in the ocean floor. This seemingly-destructive habit was investigated by University of Victoria graduate student, Erin Foster, and a team of scientists in British Columbia (BC). To their surprise, they discovered that the genetic diversity of eelgrass meadows increases when they’re inhabited by sea otters.

Eelgrass meadows, which contain long, ribbon-like plants, are popular hunting grounds for sea otters. Eelgrass beds are often home to the sea otters’ favourite food — clams! When the sea otters dive down and dig up the clams, they leave little holes on the seabed. Interestingly, these little holes, create the perfect space for eelgrass seeds to settle and grow.

Boosting Genetic Diversity In Eelgrass Meadows

Instead of destroying the eelgrass, Foster and her colleagues discovered that it was actually benefiting the underwater plants. The sea otters’ destructive habit forces the eelgrass to more readily flower, which creates genetically diverse plants.

“The pits that the otters are digging provide a spot for the seed to settle and grow — a nice sheltered place where they are getting sunlight,” said Erin Foster. 

Genetic diversity is important in every ecosystem. Typically, a diverse range of plants can withstand and recover from extreme stress — caused by heatwaves and ocean acidification. In this case, “the genetic diversity in eelgrass meadows that sea otters had reestablished was about 30% greater than if there were no sea otters,” said Foster.Benefits of Eelgrass

Benefits of Eelgrass

Why Are Eelgrass Meadows Important?

Have you ever heard of eelgrass meadows? Eelgrass (Zostera muelleri) is one of almost 60 seagrass species, and it’s one of the dominant meadow-forming species here in Australia. Diverse meadows of eelgrass and other species are especially common in southern Australia’s temperate waters. 

Eelgrass forms the base of the highly complex marine food web. The green, weedy meadows provide foraging areas and shelter to young fish and invertebrates, a source of food for migratory waterfowl and sea turtles, and spawning surfaces for some species of fish.

Importantly — eelgrass meadows also store harmful greenhouse gases, protect the shoreline from erosion, and filter toxins out of the seawater. It's an important ecosystem.

Endangered Sea OtterEndangered Sea Otter

In The Past, Sea Otters Were Nearly Hunted To Extinction

During the 18th and 19th century, otters were ruthlessly hunted for their fur, almost to the point of extinction. By the early 20th century, only 1,000-2,000 otters remained in the wild — down from more than 16,000. 

Sea otters are critical to the health and stability of the shoreline ecosystem. Sea otters have sensitive whiskers that detect vibrations, flipper-like feet, and retractable claws — making them the ultimate apex predator!

Sea otters have been protected under the Endangered Species Act since 1977, and the federal Marine Mammal Protection Act. Today, there are around 3,000 sea otters left in the wild. This new research has shown that reintroducing sea otters into eelgrass meadows is positive for conservation.

What an incredibly unusual discovery! The seemingly-destructive digging habit is actually helping eelgrass meadows to become more resilient. Now, more than ever, we need healthy seagrass meadows to store carbon, protect our shorelines and filter out toxic chemicals. Keep digging, little otters!

For more interesting stories like this, check out our Eco News category and the blogs below. 

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