Eickelberg and Warwick Seamounts
After our 40-hour steam to Eickelberg Seamount, the data collection begins!
Let’s back up a second. Why are we doing this research, and why do both the US and Canada have interest in these seamounts? I mean, don’t corals grow in shallow, tropical waters near the equator?
Shallow Water Corals vs. Deep-Sea Corals
The tropical corals that often come to mind when talking about corals and coral reefs do live in shallow waters, because they depend on sunlight. They have a mutual relationship with a type of algae called zooxanthellae. The coral provides carbon dioxide (through respiration) and a place for the algae to live inside its individual polyps. In turn, the algae provide nutrients (sugars, fats, and oxygen from photosynthesis) to the coral polyps. However, deep-sea corals live deeper than light penetrates, and therefore don’t house zooxanthellae. They gather nutrients the more familiar way—by eating. Individual polyps look like little anemones and capture nutrients and tiny animals as they float by.
And these deep-sea corals don’t build reefs but, like tropical corals, do provide unique and important habitat on an otherwise rocky or sandy seafloor. These corals often grow tall so the polyps can reach up into the water column to feed. This three-dimensional growth provides habitat that fish, crab, and other animals can duck under, hide behind, or cling to. Sponges also grow in much the same way. The benefits of this living structure are what this expedition aims to understand more clearly. We also hope to better understand the presence/absence of deep-sea coral and sponge on these seamounts, and how the environment affects their distribution in the Northeast Pacific.
More Goals of this Research
The team is also looking at how fishing impacts the deep-sea coral and sponge habitat in order to come up with suggestions for better ways to fish while not damaging the habitat that some species depend on. And that’s why Canada is particularly interested in these seamounts. While these are outside of the Exclusive Economic Zone for any country (EEZs extend to 200 miles offshore of a country’s coast), Canadian fishermen operate the only active fishery out here. They sustainably fish along the bottom using longlined pots to target sablefish (black cod).
And why is NOAA’s Alaska Fisheries Science Center interested in habitat off the coast of Washington State? Because we are interested in how deep-sea corals are linked along the coast of British Columbia from Washington to Alaska. These seamounts may be the genetic link or distribution pathway by which these corals and sponges disperse from north to south. This research aims to understand this hypothesis further.
What it comes down to is that we know far less about deep-sea corals than tropical corals. We’ve only just begun to explore deep-sea coral and sponge habitats and their supporting role for the larger deep-sea ecosystem. And this habitat is hard to reach. We’re talking 150-1000 meters for these seamount sites. 1000 meters is more than half a mile!
Highlights from September 9-10
So let’s get down to the nitty gritty. What are seeing out here? These are exciting times because Eickelberg Seamount has never been visually surveyed before, and Warwick only once in 2002. 20 years ago!
Corals and sponges! More than we expected too. When talking with Dr. Chris Rooper over lunch (Chris is the chief scientist from Fisheries and Oceans Canada), he was pleasantly surprised to see so much coral at these sites. From previous modeling and based on the limited information we do have, he was expecting more sandy bottom habitat (sandy bottom on seamounts is often from currents depositing sand on these submerged, rocky islands). And with rocky bottom comes places for corals and sponges to attach and grow.
As you can see from the images, the coral is not dense, but there is a relative high presence. In comparison from past surveys in Alaska waters, the Aleutian Islands has very high density with corals on basically every rock. The Gulf of Alaska has more sand bottom, so relatively low presence of coral and sponge habitat, while the Bering Sea shelf is mostly sand or soft bottom.
Upon first glance, this means that these two, relatively unexplored seamounts may be even more special than previously thought. But these are only the first two days and the smallest sites, so let’s see what the next three seamounts bring. We’re headed to Corn Seamount next, followed by Cobb, and finally Brown Bear.
Follow the next blog to see what else we find, more details about the innovative stereo camera system, and why it’s used vs. other methods of sampling.
