Glacial fjords home to surprise coral — but maybe not for long

Bob Stone holds a 50 year old red tree coral. (Photo by Elizabeth Jenkins/KTOO)
Bob Stone holds a 50 year old red tree coral. (Photo by Elizabeth Jenkins/KTOO)

You might not expect coral to thrive in Southeast Alaska. But it exists in the silty waters of glacial fjords. Now scientists are wondering if the coral, which serves as important fish habitat, could be in danger from an invisible threat — ocean acidification. 

Inside a lab at the National Oceanic and Atmospheric Administration’s Juneau headquarters, Bob Stone is showing me a red tree coral plucked from the bottom of Tracy Arm fjord. This one is dried, the color of ramen noodles.

“If you feel it, it feels like popcorn,” Stone said.

But in the wild, he says it’s an intense red, like the color of salmon roe.

Stone is a fisheries research biologist at NOAA. And — until fairly recently — he didn’t know that coral could exist here.

“Until 2003 nobody did. Or if they did, they weren’t telling.”

Around 2004, someone did tell. Stone was giving a seminar and a person from the audience came up to him. They said they had seen this type of coral in a glacial fjord in Southeast Alaska.

“And I said, ‘no you didn’t’ … and they showed me the specimen and it was indeed that.”

The next year, NOAA received the funding to go see for themselves. Stone had his doubts because red tree coral typically lives far below the ocean’s surface —  in places like the Gulf of Alaska and Bering Sea, at depths of more than 2,000 feet.

Glacial fjords, on the other hand, can be shallow. But its unique landscape replicates the environment of deeper water, so the coral can thrive. For Stone and the other scientists, that was a huge surprise.

“The first time I saw one, I was amazed. I didn’t know what I was looking at,” Stone said. “They’re almost more of an orange color but they’re just a huge reddish orange tree under water. To me, they’re one of the more beautiful animals I’ve ever seen.”

It also serves a very important function. Stone says scientists call the thickets of red tree coral “little forts” because they’re hideout for small species, like fish and crab.

Red tree corals are a focal point of the Deepwater Exploration of Glacier Bay National Park Expedition. These corals have been shown to be the foundation of diverse deepwater communities in Alaska. And can occur as shallow as 6 meters. Here several fish and urchins congregate around a large red tree coral. Image courtesy of NOAA- Alaska Fisheries Science Center and Deep- Sea Coral Research and Technology Program.
Image courtesy of NOAA Alaska Fisheries Science Center and Deep- Sea Coral Research and Technology Program.

But around the same time scientists were discovering just how versatile this coral could be, they were also becoming increasingly concerned about changes in the ocean.

“By the early 2000s, we had recognized the ocean was actually increasing in carbon dioxide level. That ocean acidification was happening,” said Tom Hurst.

He studies the effects of climate change on marine life at a NOAA lab in Oregon. And his primary focus is commercial fisheries in Alaska.

Hurst says, in part, the reason our oceans are becoming more acidic has to do with us.

“Primarily from the burning of fossil fuels,” Hurst said. “So, you’re taking all this carbon that was stored underground in the form of coal and oil. And as we burn it we’re releasing all that carbon into the atmosphere.”

And that becomes carbon dioxide which gets absorbed into the water. Now you’ve got a cocktail for ocean acidification. Still, Hurst says a big piece of the puzzle that’s missing for scientists is what that could mean for marine life.

“We don’t really yet have a good handle on which of those things are going to be affected, how much they’re going to be affected and how those changes are going to ripple through the food web,” Hurst said.

Already, in Washington state, ocean acidification has been linked to oysters not being able to fully develop their shells. As far as we know, that hasn’t happened in Alaska yet.

But scientists have named places like Southeast Alaska and the Aleutian Chain as potentially threatened spots. Hurst says what’s next is figuring out how — not if — ocean acidification will impact different forms of sea life.

Back at the NOAA lab in Juneau, Bob Stone is showing me a baby pollock suspended in a bottle. Typically, the coral helps shield the baby fish from predators.

“This one right here, I actually collected in the coral by hand,” Stone said.

Discovering the red tree coral in the glacial fjords has an added bonus. It makes it easier for scientists to retrieve since it’s in shallow water.  

Now Stone is conducting an experiment to see how much ocean acidification could hurt the coral down the line. It has an easily dissolvable skeleton. And scientists are wondering if the added chemicals in the water could make it harder for the coral to reproduce.

But ocean acidification may not be its only threat. The glacial fjords that are home to this surprise coral are also changing.

“Well, yeah. We now realize that, say for example, in Tracy Arm, that the two main glaciers that are there go up into the alpine, up into the valleys rather, that system will shut off,” Stone said.

When the glaciers disappear, the shallow water coral will, too.

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