"Where have all the flowers gone?"
— Pete Seeger
Sea urchins give me the creeps.
I know, they shouldn’t. An individual urchin, if it weren’t for its sharp spines, could almost be seen as a warm fuzzy — one of those fluffy, palm-sized stuffed animals that toddlers love to cuddle. Even the urchin’s colors are toy-like; many, if not most, are a not-too-subtle red or purple.
Essentially walking stomachs, without brains or eyes, urchins slowly roam the shallow sea floor in search of stationary foods which they scavenge or graze upon. And although urchins have scary-looking “mouths” — five sharp plates that snap together and scrape off bits of plant matter and underwater detritus they pull in with their pod feet — they are certainly no threat to any but the tiniest of animals. They’re just another species filling a niche in the marine ecosystem, doing their part to maintain the balance of nature.
Except now they’re doing more than their part, and the balance is tipping, irrevocably, toward ecosystem death. In many of the world’s offshore kelp forests urchins are, in fact, doing their part in the sixth extinction.
The most drastic instance is evidenced along the coastline that extends from California to British Columbia. Off California, the purple sea urchin’s population has increased by 10,000% since 2014! Consequently, the region’s formerly vast kelp forests, home to a rich diversity of species that includes many of commercial value, have been 90% devastated — in just five years.
For all practical purposes, that devastation is permanent. Sea floors that once hosted kelps waving in the current have become “urchin barrens,” vast areas covered with millions upon millions of purple urchins packed together so tightly that the sand beneath them is invisible.
And although they have eaten all the available kelp, the urchins won’t starve and allow the forests to come back. Urchins can survive for decades without food, waiting for their next bite. Any resurgent kelp will be immediately exterminated.
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The problem is moving north. An estimated 350 million urchins have appeared on a single Oregon reef.
How did this happen?
The principal predator of the purple sea urchin is — or, more accurately, was — a huge sea star known as the sunflower starfish. Growing up to a meter across, these voracious predators consumed millions upon millions of urchins, keeping their population under control.
Where have all the sunflowers gone? In 2013, they were attacked by “sea star wasting disease.” According to the online environmental newsletter Mongabay, the disease “kills off starfish rapidly: diseased sea stars develop skin lesions, their arms detach from their central disc, their central organs spill out and individuals die, living behind bits and pieces of limbs and bodies” — to be scavenged, no doubt, by sea urchins. As a result, there have been massive declines in sea star populations.
Why did this disease, which has been known to kill small numbers of sea stars in the past, suddenly “go viral?” Again, from Mongabay (and several other sources): “…the largest declines in the sunflower sea star numbers coincided with abnormally high sea surface temperatures, suggesting that warming oceans due to climate change could have exacerbated the disease’s impact.”
Ah, global warming. Seems like its effects are appearing … globally. Soon it won’t be “in the news.” It will be all the news.
Back to the creeps: I see billions of sea urchins creeping relentlessly across the sea floor like some weird, unstoppable Martian invasion in a sci-fi film. And on the horizon, I see a whole planet that resembles an urchin barren.
We could well ask “When will we ever learn?” But the unwelcome answer might be that we’re learning too late at our ecological house.