I’m a big fan of kelp. I love seeing it waving in the currents off the Pacific coast. Thick rafts of kelp floating on the surface at low tide is a tell that a complex ecosystem thrives beneath.
When I was a kid playing in the ocean in Southern California, kelp was a gross-out device. We’d fling strands at one another, then freak out if the icky strands touched our skin. Still, we were fascinated by the plant’s broad, slimy leaves (called blades) and gas-filled bulbs (pneumatocysts) that pull the kelp’s long stalks toward the surface.
The adult me also likes kelp. It is a great source of monosodium glutamate, or MSG. This controversial flavor enhancer was first extracted from kelp, and kombu — the culinary name for dried kelp — is an essential ingredient in dashi, the ubiquitous Japanese soup stock.
Kombu is covered with a fine white powder: MSG. That’s why dashi is such an umami bomb.
It turns out sea urchins are cocaine bears of the sea. The urchin’s preferred white powder is MSG, however, and the spiky grazers are eating the kelp forests of the Pacific coast at an alarming rate. The spread of sushi from tony coastal restaurants to gas stations across the Midwest isn’t enough to keep sea urchins in check.
Alas, sea urchin gonads are still a minor player on the sushi stage. Uni scares less adventurous eaters.
Kelp forests have long defied simple solutions for restoration. When fur traders in the 1800s wiped out coastal sea otters (otters are adventurous uni eaters) the urchin population exploded. But this more recent urchin boom has so far been unchecked by the semi-recovered otters of California. The absence of another predator in the kelp forest — the sunflower sea star — may be why.
Sea stars, by the way, are what most of us call starfish. Concerned the public might confuse a 24-legged invertebrate for a grouper, scientists decided the colloquial starfish moniker needed replacing.
The sunflower sea star was wiped out a decade ago by sea star wasting syndrome, which may be caused by a virus. Before that, there may have been as many as 5 billion sunflower sea stars eating urchins from Baja to Alaska.
Climate change is another factor. The normally frigid Pacific was engulfed by a blob of warm water off the coast of California in 2013 and that may have hastened the sea star’s decline while giving the urchins a boost. The results are barrens where urchins have clear-cut the kelp forest to extinction.
One solution is the Steller’s sea cow. Well, it’s not really a solution as Steller’s sea cows are extinct. But reimagining the impact these kelp-feasting sea cows, which measured up to 30 feet long, and weighed up to 10 tons, had on the coastal ecosystem might offer clues on how remaining kelp forests might be saved.
It’s possible grazing sea cows — if you’re attentive to livestock grazing trends you’ve heard something like this before — thinned the kelp forest allowing more sunlight to penetrate to the seafloor. And more light means more growth, maybe enough to distract sea urchins from munching too rapaciously on kelp.
Maybe, though as with other fisticuff-inducing debates about extinct species, such as whether Tyrannosaurus rex was a predator or scavenger, we’ll never really know.
What we do know is that the loss of the coastal kelp forests will have a profound impact on the Northern Pacific Ocean, and that impact may extend upstream anywhere marine species travel inland via the rivers of the region.
In the meantime, sushi lovers need to up our uni game. Also, never boil your kombu to extract MSG. Bring your stock pot to a low simmer, then turn the heat off. Let the kelp soak for a spell, then get that slimy blade out of there.
Dashi turns from umami bomb to bitter in an instant.
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