March 1, 2006
What do you hope to learn by studying Salps?
Chadds Ford, PA
One thing we hope to learn is about how salps make their living in the ocean, such as: what food they eat (and what eats them), how much food it takes to keep them alive, and how they manage to make so many babies so fast that they form huge swarms in the ocean. A big question is whether they interfere with other animals, like krill, by eating the same food the krill eat, so the krill don't always have enough. There are huge numbers of salps down here in the Southern Ocean, but nobody knows much about the species that is here, Salpa thompsoni. Some scientists have tried to estimate the numbers by catching them in nets, but until now no one has been able to study the live ones. We are lucky to have live salps every single day of our cruise!
Of course, the scientists on the cruise like these strange creatures very much, and just want to find out all about them. There's a lot we don't know yet—both about how the ocean works, and about salps. For instance, we don't know how long they live, and what they do in the winter when there isn't much food in the water. There's a long way to go to know all about their place in the ocean ecosystem.
I hope that answers your question, at least a little. Thank you for writing, and I hope you keep exploring our Web site!
Woods Hole Oceanographic Institution
My name is Lauren and I'm from St. Michael’s University School in Canada. Right now were studying and pretending (sort of) to be scientists on the same expedition you are on. I'm Kerri Scolardi in the project.
Our teacher, Ms. Johnson, has had us write entries from the people we were to be into our own private scientific journal. Also, in our journals we write critter of the day, etc.
So my question (for Kerri if she answers this) is: Which critter of the day has been your favourite to study or just look at so far?
I am so pleased you asked me this question. My favorite critter of the day is hands down the ctenophore (spoken: teen-a-fore), or comb jelly, from Day 6. The species you see in the picture is Callianira antarctica. This is the species I studied for my master's thesis, so it is near and dear to my heart. C. antarctica is a tentaculate ctenophore, meaning it has long tentacles used to capture prey. The tentacles of this species can reach up to ten times the body length of the ctenophore, and have side branches, or tentilla, that are usually purple. While fishing for prey, the ctenophore drifts in the water with its tentacles "set out" to either side and the tentilla streaming downward, forming an efficient fishing net. One or many small crustacean prey will become entangled in the sticky tentacles, after which the ctenophore will haul up the tentacle, rotate a few times to bring the catch to its mouth, and then "swallow" the prey whole. Fortunately, most ctenophores have relatively clear bodies, allowing us to view the contents of their stomach. This makes it easy for us to study what they eat, how much they eat, and how long they take to digest their food.
We have not yet seen C. antarctica this cruise, possibly because most of our sampling has occurred off the shelf of the Antarctic peninsula, and C. antarctica might be located closer to land this time of year. We often see two species of lobate ctenophores during our dives. Lobate ctenophores have large sticky "lobes" they use for catching prey. One of these ctenophores has possibly never been described before. Unfortunately, this ctenophore is very fragile and the lobes are so large that it has been challenging to collect this animal whole! Almost all of the ctenophores we have collected so far have had numerous small krill in their guts. I am currently running digestion time experiments with these animals. I had hoped to do more work with C. antarctica this cruise, however, gelatinous animals are unpredictable, and in oceanography, conditions are almost never perfect, so you do the best with what you can get.
Have fun with your journal, and I hope you are a better rested "Kerri Scolardi" than the real one!
Mote Marine Laboratory
Are the Salps replacing krill? What is a Salp chain?
Grade 6 St
St. Philip Neri School
East Greenville, PA
Thank you for looking in on our site, and writing in questions!
A salp chain is one phase of the salp reproduction cycle. We are putting up a "Hot Topic" on salps that explains their reproduction. The chain is a series of identical salps that are formed by the parent, all connected together. They spend their lives hooked together, and can swim better this way.
The short answer to the first part of your question is: we don't yet know if salps are replacing the krill in the Southern Ocean. In some areas, there seem to be more salps than there used to be, and in those same areas there seem to be fewer krill. But the Southern Ocean is very large, and we don't see all of it at once, so we can't tell if this is true everywhere.
Some scientists think that when there is more sea ice, it's better for krill, and when there is less ice, it's better for salps. In the area around Palmer Station, there has been less ice for a few years. And around the whole continent of Antarctica, there has been a little less sea ice forming in the winter. But some areas have as much, or more ice.
It is a complex situation, and weather here changes all the time. We cannot say yet whether warming ocean temperatures will continue, and mean there will be less ice, and whether less ice will mean more salps and less krill. Our studies on this salp species will, we hope, be a small part of the answer. One of the things we are trying to do is find out whether salps eat all the same things krill do, and that might tell us whether the salps keep krill from getting enough food. Another is to find out how many babies these salps can make in a short time, and how fast they reproduce. There is a lot we still don't know about how ocean ecosystems work, and we know less about the Southern Ocean ecosystem than other ocean ecosystems. There's work for future scientists!
We hope you keep watching our web site, and thanks again.
Woods Hole Oceanographic Institution
We are in an adult education class at Lane Community College in Eugene, Oregon. We have been studying nutrition this term so we decided to look at your menu. We wonder if anyone has put on any weight. We are worried about your cholesterol. Also what do you do for exercise? Do you get enough exercise doing your work? Does your body need more calories when the weather is cold, especially the divers?
The students in Cathy Russell's adult ed class.
Dear Cathy and students:
Thanks for checking our site, and writing in. It's an interesting question.
I know what you mean—there's so much food, and four meals a day! Good nutrition is really important, and all of us try to be careful about what we eat.
I don't know whether any of us will put on weight. We won't know until we get back, and can stand on a scale! After three weeks on the ship, nobody looks as though they're putting on weight. But there are some factors that may help us not gain as much. First, a lot of people in the science group are up for many hours, maybe only sleeping 4 or 6 hours a day for days on end. That's just because we may only get one chance to be here in the Southern Ocean, and we have to get as much work done as possible while we're here. So we may burn more energy that way. Also, lots of us are standing up most of the time, constantly bracing ourselves against the rocking motion of the ship, using muscles all the time—maybe that helps, too. And also, this is only about a month away from our normal eating habits—we don't have this much food all the time!
There is a gym on board, and many of the crew and scientists use it almost daily. The ship's marine technicians and crew have demanding jobs, being on deck and handling nets and equipment, so they may need more food than normal. The divers do get cold when they dive, so maybe they need a little extra, too. About half our group are young, athletic people in their 20s, so they need a little more food than the rest of us. And some of us try to be careful, eating only a little at each meal.
Even though we are away from land, the steward has stocked the ship with fresh foods, so there are always salads, vegetables, and fruit, and it's not hard to find healthy things to eat. But the cooks prepare delicious hot dishes that are very comforting at midnight on a cold night, when you know you'll be up working until 5 or 6 a.m.! It would be hard to imagine a cruise like this without their cooking.
Thanks for watching our Web site, and for writing us. We will all have to see whether we've gained weight, when we get back to land!
Woods Hole Oceanographic Institution