On a dreary Wednesday afternoon, in the damp, dimly-lit basement of the Sitka Sound Science Center, the wheels of discovery are turning. And it’s researchers like Dr. Sarah Gravem who are turning them.
Over the last four years, from the coast of Mexico to the Gulf of Alaska, a startling change in the ocean habitat is happening. Invisible from land, beneath the waves of the Pacific, kelp forests have been fighting a losing battle.
Scientists have taken notice as once thriving kelp forests, and the ecosystems they support, have transitioned into rocky, deserted wastelands.
“The Santa Cruz lab over the last few years has noticed that big lush kelp forests full of kelp, full of other critters, fish, abalone, et cetera, are disappearing and transitioning into urchin barrens, which are more bare rock, and a lot of sea urchins just cruising around and grazing all the algae down and preventing other things from using that algae as a place to live or thing to eat,” said Gravem.
Gravem, a postdoctoral scholar and marine ecologist from Oregon State University, is one of six researchers from Santa Cruz and Oregon conducting research in an attempt to unravel the kelp’s decline.
“In Oregon, we’re just now seeing kelp starting to collapse,” explained Gravem. “And we’re seeing inklings of it here up in Alaska and we are hoping it’s not on its way.”
Like their terrestrial counterparts, kelp forests rely on an intricate web of predators and prey: Sea otters, urchins, and starfish. On remote shores, that web remains intact; closer to town, however, the system has been thrown out of balance. And kelp forests suffer.
“One of the reasons we think it might be happening is the decline in the sea stars. They’ve been wiped out in Oregon, California, most of Washington, and they’re here in Sitka,” said Gravem.
The sunflower sea star, an echinoderm known for its excessive size and numerous limbs, has been making a slow recovery in Sitka.
“They got wiped out pretty badly, but they’re starting to come back a bit. And so the sunflower sea stars are the top predator. And they eat sea urchins, and sea urchins eat kelp,” she said.
But even as the population rebuilds, years of damage have already been done. As Gravem explains, the sea stars were wiped out by Sea Sar Wasting Disease, a plague-like sickness causing lesions, body fragmentation, and eventually death. It’s when these sea stars, who once played the top predators, died that scientists saw the biggest transitions in the kelp. By observing the ways kelp, urchins, and sunflower sea stars interact, Gravem and her colleagues hope to unravel the kelp’s decline.
Set to a soundtrack of humming water pumps, and bubbling sea water, Gravem’s research comes alive. But it’s not the high tech science lab you might imagine. A collection of plastic tubs and barrels comprise the control tanks, and data is collected by hand every few hours. It’s within these unassuming tubs that our main character, the sea star, sheds light on the world of underwater forests.
She walks me through the lab, exposing an array of tiny underwater worlds.
“What we’re looking at right now is a bunch of laboratory experiments that we have running, looking at, for example, how fast sunflower sea stars eat urchins and eat snails,” she said enthusiastically. “And then how fast this urchins and the snails eat kelp. And then over here is when you put them all together, how does the presence of the sea star benefit the kelp? And how does that change their behavior?”
Gravem lifts a seas star out of its mini habitat, a bright orange mass of spiny arms. I balk at the size of it, but she assures me this star, an adolescent by her account, is on the smaller end.
“We actually had to go all the way across Chatham strait to get big ones. They’re not close to town. And so these ones are medium size, and they can get like the size of an extra-large pizza. They can get really, really big,” she said, holding the glistening invertebrate to the light.
As she explains, humans have long stewarded our terrestrial habitat, but have failed to notice subtle changes in the ocean. Losing kelp forests could have potentially devastating implications for coastal communities. But in this dark basement lab, within these buckets and barrels, is a hope for the future.
