Submitted by Anonymous on Wed, 11/03/2010 - 18:21
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Antarctic Seafloor Ecology

I am in Tina's English 1A class and it would be very helpful if one of the team's divers could answer these questions. 1. What are the differences between diving in Antarctica and diving anywhere else in the world? 2. What extra precausions do you have to take? 3. What, if anything has changed since your first dive in Antarctica? In gear, procedure, safety precautions, etc. 4. What changes have you seen in the seafloor since your first dive? 5. What is the biggest challenge when diving in Antarctica (other than the cold water) and how do you over come it?

Wed, 11/03/2010 - 20:17

Tina Sander

Hi there!Here are responses from Kamille, our newly arrived diver!
They are great - very thorough.
Tina

Fri, 11/05/2010 - 18:55

Anonymous

I cannot see the responses.

Mon, 11/15/2010 - 10:33

Tina Sander

1. What are the differences between diving in Antarctica and diving anywhere else in the world? The temperature is one big thing! But the thing I notice the most is the water clarity. We dive during the austral spring-summer (Oct-Dec in the southern hemisphere) and early in season the water is oligotrophic, meaning very few phytoplankton and zooplankton in the water. This is because the ice is really thick through the winter, preventing light from getting to the water and triggering the phytoplankton to photosynthesize and start reproducing and the zooplankton to eat phytoplankton (and each other) and also reproduce. When all those things in the water column are eating and making babies, the visibility declines. That's what we call a bloom, when the water turns brown or green or even red because all these microscopic organisms are eating, growing and reproducing. So early in the summer season, the visibility can be as great as 1000ft, meaning that I could see something 1000ft away from me, looking horizontally through the water. That's really, really clear! Another thing that is different from most places is that we are diving through thick ice, sometimes as much as 4 m thick. It may be pretty dark underwater because of the thickness of the ice, but when a diver aims a dive light at something far away, he or she can still see it.
2. What extra precausions do you have to take?
There are 2 main threats to divers in Antarctica: getting too cold and not being able to find the hole in the ice that the diver descended through.
We deal with the cold by wearing drysuits, which are laminated nylon or neoprene and are waterproof. The have latex seals at the wrists and neck to keep the water out. We wear big fluffy dive underwear to create an airspace in the drysuit. THat's what keeps us warm. Our bodies warm the air and the dive underwear act as insulation from the cold. Then we wear multiple dive hoods to keep our heads warm and waterproof gloves that slide on over our drysuit sleeves. So except for a small space where we wear our masks and the area around our mouths, the rest of us is protected from the cold water. All this gear is really bulky and hot when we are on the surface before we go in the water, but once we are in the water we are grateful for it.
In order to keep track of the dive hole we put a weighted line down through the hole to mark the hole's location. The line has flashers and flags attached to it, flashers which blink on and off and flags which have a checkerboard pattern. So as long as the divers pay attention to where they are going, glancing around occasionally to make sure they can still spot the flashers and/or flags, they can keep track of the hole and get back there when they are finished working and ready to end the dive.
We also always have a dive tender on the surface, to help divers get into and out of gear and to notify emergency personnel if the divers don't return when they are supposed to.
3. What, if anything has changed since your first dive in Antarctica? In gear, procedure, safety precautions, etc.
I actually started diving in Antarctica last year, so the gear, procedures, safety precautions, etc. are the same. But I have heard stories from people who started diving in Antarctica in the 1950s and 1960s, when SCUBA science was still in its' infancy. At that time there were no national organizations to train divers and ensure that everyone followed the same standards. Medical science also hadn't figured out what aspects of diving might be dangerous to divers. So divers could stay down much longer than they do now, and dive much deeper. Now we know that diving too long or too deep without following proper steps can cause injury or even death due to the gases that build up in divers' blood. Gear has also gotten much better. The first Antarctic divers wore wetsuits! They would get so cold that their body temperature would get dangerously low and they would have to sit in hot water baths after dives to warm up. Earlier dive regulators would often freeze up, causing air to free-flow. That causes the SCUBA tank to drain quickly and the diver could run out of air. People who dove 40-50 years ago are really pleased by the advances in diving technology. Dives are not only safer, but also more comfortable.
4. What changes have you seen in the seafloor since your first dive?
I haven't actually seen any changes while diving. But my job before I got to come here and dive was to analyze a lot of the data researchers collected in previous years. Until 2003, the McMurdo research station dumped its sewage into the water under the ice. People from our research team were funded to look at how the sewage affected the critters that live on and in the sediment. We call those critters benthic fauna. Benthic means on or near the bottom. We sampled at locations closer to and farther away from the sewage outfall and saw that the species assemblage, or types and numbers of critters, was different depending on how close they lived to the sewage outfall. Now that the sewage is treated and no more is dumped in the water, our team is collecting samples to see how long it will take for the species assemblages to return to pre-sewage outfall conditions. In analyzing data from the late 1980s to now, we have seen significant recovery in the benthic faunal populations, meaning the bottom is returning to an undisturbed state. So that is one change that has taken place on the seafloor.
5. What is the biggest challenge when diving in Antarctica (other than the cold water) and how do you over come it?
The cold water is the biggest challenge! Because it is so cold we have to wear completely sealed suits and fluffy dive underwear to stay warm. The more air in the suit, the warmer the diver stays. This results in lots of buoyancy, meaning that we have to wear very heavy weight belts to descend. Antarctic divers commonly wear weight belts of 44-52 or more pounds. Those belts are extremely heavy to carry around when preparing for a dive. We regulate our buoyancy by adding or releasing air from our drysuit. If we release too much air, not only will the suit not keep us as warm, but we will begin to sink as well. In addition to doing the underwater research, a diver also has to keep track of how much air is in his or her drysuit and how much is in the tank and also where the diver's buddy is. And if the ice is thick enough and it's dark underwater, the diver has to do all that and use a dive light to see what they are doing. Diving in Antarctica is very challenging, but it is very worth it. The Antarctic underwater ecosystem is the most pristine place in the world, and it is a privilege to get to see it firsthand.

Mon, 11/15/2010 - 14:23

Anonymous

Thanks! The answers are very helpful.