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MESA Archives: Aleutian Islands Deep Water Corals Cruise, Precruise

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Hear NOAA Fisheries Biologist Jon Heifetz discuss the Aleutian coral research in these audio clips, collected in a precruise interview, conducted earlier this year by reporter Sonya Senkowsky.


Q. Why did you choose the central Aleutians as the location for your study? Could you describe your approach?

 

Hear answer
(373KB MP3)

A. Working in the central Aleutian islands around the town of Adak, it's about a 500-mile long stretch of coast. We chose the central Aleutians because we had looked at some previous trawl survey data from our routine surveys for assessing fish abundance, and when we summarized that data, it looked like there was a really high diversity and abundance of deep-sea corals out in the Aleutian chain. And recently there's been concern about the impacts of fishing gear on this type of habitat.



Q. Now, of course, you went and already explored Aleutian corals in this region at shallower depths then you plan to go this time. Could you describe your earlier studies?

 

Hear answer
(260KB MP3)

A. The first year we went out there, in 2002, we used the Delta submarine, which is a two-man submarine. There's an observer, usually a scientist, and a driver, who's an experienced driver, and we covered depths from about 50 meters at the shallow end, down to 365 meters, which is the deepest the Delta submarine can go.



Q. So, what was it like down there?

 

Hear answer
(773KB MP3)

A. Well, the landscape is really varied. You have habitat that's just sand, marine sediments. You have other habitat that has rocks interspersed with sand, and then you have really rocky habitat. There's submerged volcanoes in the Aleutian chain, it's one of the most actively geologic areas in the world. It was not glaciated previously like other places in Alaska, so you have a lot of bedrock - and on these rocks, there's corals and sponges growing on them. The areas, most of the dives we took are below the photic zone, where light can reach, so we have very strong lights. The corals that grow down there don't depend on light. That's different than corals in tropical areas -- which, they depend on symbiotic algae for part of their life cycle - so these corals basically are filter feeders. And we were just, we knew there were corals down there, but in some of the areas we didn't expect to find, you know, basically these gardens of, just, corals growing on sponges, sponges growing on corals - very, very diverse and very colorful.



Q. Could you tell a little about the corals? What do these deep-sea Alaska corals look like? What do researchers know about them?

 

Hear answer
(750KB MP3)

A. Yeah, the largest ones are probably nine-feet tall at the largest, and then we have they're branched just like the gorgonians you would see in tropical areas. One of the unique things about these corals is that they are very long-lived; some of the aging that's been done on them, hundreds of years old for some of them, so they're very long-lived. We don't know a whole lot about how they reproduce, so if they are disturbed by fishing gear or other things, we don't really know how long it would take for them to recover, so they're susceptible to that. They're often bright red; there are a couple species - one of them is known as a bubblegum coral. It comes in two different color variations: it's white, and then you have a pinkish or a reddish one. There's what's known as reddish tree coral - that's one we aged - and that one is hundreds of years old, if not older. And then we have hydrocorals, that's another group of corals, really a hard coral, and we don't really know any way to age that type of coral.



Q. One of your goals is to look at the role of corals in the ecosystem - how important they are to fish and crabs, for example. From what you know so far, what role do the corals seem to play?

 

Hear answer
(287KB MP3)

A. Well, we're really not sure. There's oftentimes fish really closely associated with corals. The ecological role is they provide cover for fish. And I work for the National Marine Fisheries Service, and that's one of our mandates, to assess the impacts of the fisheries on the habitat with the idea that if you're protecting the habitat you're also protecting fish populations, so the fisheries are sustainable for the long run.


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