By Steven Louie, Associate Producer, NBC News
As dawn approaches, teams load oxygen tanks, wetsuits and underwater cameras into vans and trucks. A motor boat is set on a trailer, and students prepare measuring tape and clipboards -- an urgent expedition is underway. At first light, the team of researchers heads down the coast from the University of California Santa Cruz to Monterey Bay.
For months, marine biologist Pete Raimondi and his team have been diving in these waters, searching for clues to an epidemic called starfish wasting syndrome. The mysterious disease has decimated starfish populations in the coastal waters and tide pools along the West Coast, from Alaska to Southern California. In some cases, 95 percent of the sea star population has been wiped out.
The infection starts with a small, white lesion that quickly spreads and consumes the animal, often overnight.
"What you've got is just a mass of tissue that's decomposing, sometimes turning into this goo-like mass underwater," Raimondi said.
NBC News' footage of Raimondi's dive reveals a dire situation. Droves of infected starfish with missing limbs, falling apart before one's eyes. Still, Raimondi says, what's most worrisome is what one doesn't see. Two species that used to thrive in Monterey Bay have already vanished.
"Two months ago, these species that are missing now were plentiful," Raimondi said. "And over the last two months, they've disintegrated and they're basically missing from this location."
Sea stars, commonly known as starfish, are what scientists call keystone predators. Dominant in their environment, starfish are crucial to keeping the species they prey on -- such as mussels and clams -- in check.
"If there weren't starfish, animals that reproduce very, very effectively [would] out compete. And you'd end up with just big beds of mussels, with no other living diversity around them," said Michael Murray, lead veterinarian at the Monterey Bay Aquarium.
While the potential fallout is known, the causes are still under investigation. Scientists have attributed previous outbreaks of starfish wasting disease to warmer waters during El Nino years, most notably in the 1980s and 1990s -- but this year is not an El Nino year.
"Everything is on the table because we don't know what's causing it," Murray said.
Some of the prime suspects are localized warm water events, low oxygen levels and ocean acidification, but researchers aren't ruling anything out.
"I've had probably 100 emails thus far saying, 'Well, what about Fukushima because of radiation?' Raimondi said. "We haven't ruled that out yet, but we're clearly not ruling that in."
Raimondi's team is trying to map the location and timing of each outbreak, in hope that analyzing conditions in the affected areas will help identify the cause. And they're calling on the public to help, encouraging divers who observe outbreaks to enter their location and make notes on the team's website.
"We're at the beginning of this," Raimondi said. "If we have a spot here and a spot up there, you know, 20 kilometers and everything in between fills in, then we could have a really powerful event going on that would take a long time to recover from."