It's sometimes said that we know more about the dark side of the moon than we do about the ocean floor. One's a lot closer, but they are both hostile, difficult and expensive places to visit. Ocean scientists continue their work, including a group sponsored by the U.S. ocean research agency NOAA that has been busy off the U.S. East Coast, studying deep sea corals. They've been working on board the research vessel Seward Johnson, which recently was in port at Charleston, South Carolina.
Standing in a low-ceilinged workroom aboard ship, surrounded by computers, video gear and nautical charts, chief scientist Steve Ross explains how the coral specimens they bring up from the bottom provide a window into the past. Coral growth can be seen in rings -- tiny versions of the growth rings of trees -- that serve as a library of information about ocean conditions in the distant past.
"You know, you probably heard that you can count the age of a tree by its rings," says Dr. Ross. "But the width of the rings gives you information about its growing season. You can tell potentially whether it was a wet climate or a dry climate, hot or cold, good or bad for growth. This is a little bit different situation, but we've determined that a lot of these corals live to be quite old. Anywhere from a few hundred years old to almost 1,000 years old potentially."
Analyzing those annual rings for isotopes of chemical elements -- including carbon and nitrogen and oxygen -- opens a window on the ocean environment in centuries past. "So we can go back to, say, potentially the year 1700," continues Dr. Ross, "and find out what the temperature of the ocean was, what the pollutant load was, and what the status of the productivity was. And we can do that every year up to the present."
The scientists have been diving to the bottom in a small research sub, bringing up samples of coral and other marine life. In a conversation with several visiting journalists, one of the first questions was, have you discovered any new species. The short answer is, maybe, but the final word will have to await further study of specimens in land-based labs, after this expedition ends.
The identification of new species isn't what it used to be.
For centuries, biologists compared characteristics of a plant or animal to other similar organisms, not only to determine whether they were looking at a new species, but also to see how species were related to each other. You don't have to be a scientist to realize that a tiger is pretty closely related to a lion, but only distantly related to an elephant. Martha Nizinski is a zoologist with NOAA, the U.S. ocean research agency sponsoring this expedition. Her approach to taxonomy -- the classification of organisms -- is the traditional method. "When you're doing taxonomy and identification, you use a lot of the old literature," explained Dr. Nizinski. "So some of these species may have been described in the early to late 1800s, early 1900s. So we have to look and see how it compares to those original descriptions."
Dr. Nizinski explains the unknown organism is studied with careful attention to a variety of physical attributes. "We'll use a crustacean as an example. We take measurements of its carapace, which is its shell. We look at various combinations of spines, the shape of the shell, the shape of the organism, how it carries its abdomen, the type of legs it has -- so there's a whole variety of characters that we look at."
But many other taxonomists now use DNA to classify species. Another member of this expedition, Cheryl Morrison, uses genetic identification. She says it's particularly useful with coral, where the shape and structures can be greatly influenced by the environment in which it grows. "You know, looking like a very long branching pattern in one area, and then a little glob of coral polyps all over the place in another area, but it's really the same species -- it could be, it might not be. And so the genetics helps us in those types of situations figure out if we're really looking at the same thing."
DNA taxonomy employs basically the same technology used in police investigations, except instead of tying a suspect to the crime scene it tracks genetic similarities between known species and an unknown specimen. Although she has embraced the new method, Dr. Morrison doesn't reject the older.
"I wouldn't say it's better. I would say that they should go side-by-side, hand in hand," offered Dr. Morrison. "There are times where things are very similar, that we couldn't tell apart by morphology, but sometimes DNA allows us to separate things that we wouldn't have been able to, based on morphology. But often -- and I think that this is when this is the strongest technique -- is when they agree."
Of course, sometimes they disagree.
So if these scientists exploring the edge of the continental shelf in the Atlantic Ocean off the southeastern U.S. do identify a new species, so what? Chief scientist Steve Ross and the other scientists on board the ship may be focused on knowledge and discovery, but the taxpayers behind this government-funded expedition might wonder, how am I going to benefit?
"Usually that's the stumbling block question for most of us, and we say, gosh I'm not sure. But quite a lot of the time we're accumulating information such as, there are biomedical potentials. We're not doing biomedical work, but some of the organisms in the deep sea have biomedical potential. There are groups [of researchers] that are beginning to explore that. That has a worldwide impact. Cancer research chemicals, for instance, is one area where deep sea research has been important."