THE SEA OTTERS WHICH POPULATE THE NORTHERN PART OF THE PACIFIC OCEAN, THEY PLAY A VITAL ROLE IN PROTECTING THE COASTAL ENVIRONMENT. LIKE IN THE SONG “AT THE EAST FAIR”, THE OTTER EATS THE STRIPED CRAB, WHICH IN TURN EATS A SEAWEED FUNDAMENTAL FOR THE COHESION OF THE SANDY BANKS OF THE MARSHES
Otters: an eclectic family
The sea otters (Enhydra lutris), as family members Mustelidaeare close relatives of weasels and martens.
Their life is closely linked to the ocean, as they spend most of their time swimming and hunting in salty waters. These skilled swimmers, equipped with a waterproof coat, stand as an extraordinary example of adaptation to marine life.
Their diet is based mainly on crustaceans, with a predilection for coastal crabs.
As for their acrobatic hunting ability, it is truly astonishing: they swim underwater, using their flattened tail as a propeller, and capture prey with incredible dexterity.
Well, i coastal crabsoften chosen as targets, represent a culinary delight for otters.
Let’s find out what makes these fascinating animals so special.
Guardians of the salt marshes
Nell’Elkhorn Slough, marsh and estuary on Monterey Bay (California), coastal erosion is approximately 30 centimeters per year. It is caused by various factors, including the rise in sea levels, a consequence of climate change.
This circumstance is putting the stability of the coasts and the vitality of the surrounding ecosystems at risk.
The salt marshesthey are in fact “natural sanctuaries” for the wildlife.
In this context of vulnerability, the sea otter plays a valuable role.
It helps keep the sandy banks of the marsh intact.
And here another actor enters the scene: the striped crab (Pachygrapsus crassipes), crustacean that feeds on the roots of Salicornia pacificaa marine algae essential for the cohesion of the sandy banks of the marshes.
Let’s try to understand better…
A singular experiment
A team of researchers, led by the co-author of the study Brent Hughes, marine ecologist from Sonoma State University of Rohnert Park, California, explored the connection between sea otter predatory activity and erosion mitigation.
The researchers then conducted an in-depth experiment, temporarily excluding otters from some areas, to evaluate the direct impact of their return on vegetation and erosion.
Result?
More otters less erosion
The analysis revealed a surprising link between the presence of sea otters and the health of wetlands.
In those areas where otters could feed on burrowing crabs, erosion levels were in fact significantly lower than in other areas where they were not present.
How come?
When i crabs “eat algae” are reduced (numerically) due to otter predation, the algae have the opportunity to regrow.
In an area where erosion threatened to eat up 30 centimeters of land a year, the return of the small mammal has dramatically slowed this process, which is now just 10 centimeters per year.
But the positive impact is not limited to local flora: otters also encourage the growth of seaweed and giant kelp, creating a ripple effect that extends far beyond their specific predation activity.
«It’s almost as if, wherever they go, they protect the vegetation.” Hughes enthuses.
Jane Watsonecologist from Vancouver Island University di Nanaimo (Canada), believes sea otters could extend their beneficial influence to other salt marsh habitats. For example, San Francisco Bay, with its vulnerable marshes, could be the next field of action for these marine creatures, once on the brink of extinction.
At this point it is useful to spend a few lines on the risk that the protagonists of our article took.
The return of the otters
In the twentieth century, sea otters were on the verge of disappearing due to the merciless hunt, essentially linked to their precious fur. Fortunately, the story of these marine creatures has taken a positive turn thanks to joint conservation efforts.
Which has led to a renewed balance in marine ecosystems.
Today, the salt marshes of Elkhorn Slough have become an extraordinary theater for the resurgence of sea otters.
A factor that, as the researchers point out, in the magazine Natureproduces a positive effect on coastal dynamics.
«It is extraordinary! – he states enthusiastically Jane Watson -. A single animal, the sea otter, can, through its predation, mitigate the effects of erosion effectively.”
A double triumph
Sea otters, in addition to representing a triumph of conservation, have become real “heroines” of brackish coasts, capable of reversing the fate of erosion and inspiring a narrative of ecological renewal.
Their story is a hymn to the resilience of nature and a reminder of human responsibility in protecting and respecting wild life.
An eloquent example of how the restoration of a single predator can have beneficial effects on an entire ecosystem.