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November 18th, 2013

Our First Day of Marine Sampling

 by Andrew Klein

Andrew's head

Well readers, today is the first day of the marine sampling portion of our study. We are very excited as it is one of the highlights of our field season so the next few days should be fun. If you are interested in our marine sampling you can also watch a short videos of us drilling dive holes and our later use our marine benthic sampling.

Over the course of our project we have been very lucky, and privileged, to work with the scientific divers of the United States Antarctic Program.  These are some of the best divers in the world.  We have worked with two of them, Rob Robbins and Steven Rupp for many seasons.  Their considerable expertise and experience in Antarctica diving makes our project possible and they have provided valuable guidance to our own Terry Palmer who now also dives in these frigid waters. Indeed it is one of the highlights of our season to be able to work with these guys!

This year a third diver – Martin Schuster – was also on station. Martin was a graduate student of Dr. Brenda Konar who has also dived for our project and because he was Brenda’s student we knew he would be a great diver as well.  Martin has dived in Antarctica on previous occasions, last season at McMurdo, but previously at Palmer Station with underwater photographer Norbert Wu.

Rob Robbins - Mr. Incredible
Rob Robbins - the Mr. Incredible of the Antarctica Dive World

Scuba Steve Rupp
"Scuba" Steve Rupp

Martin Schuster
Martin "Mr. Reliable" Schuster

Last, but not least our own colleague Terry Palmer will be the fourth diver on our project this season.  Terry has dived the past two seasons as well.  Your commentator has no deep desire to dive into these frigid waters, but has done a fair bit of dive tending over the years.

People enjoy diving in Antarctica because the water is very clear and visibility is great.  However, the water is cold. Because sea water contains salt it freezes below 0° C (32° F) so the water temperature the divers work at is roughly -2° C or 28° F, which is really cold.

Each year, we collect samples at three stations located along three transects (A, D and E). Transect A is in Winter Quarters Bay that has been impacted by a variety of environmental pollutants. Transect D is located off the station’s sewage outfall. Fortunately, however, today we are diving at our control transect E. It is located off of the station’s intake Jetty and is a site we believe is fairly representative of un-impacted conditions at McMurdo Station. That is, the benthic fauna as well as the concentrations of various chemicals are what we would expect in the absence of localized human activities. It is also a good place to practice for the other two transects.

The three sites along each transect that we dive on are labeled 1, 2 and 3 (or shallow, medium and deep).  The depths at which samples are collected are 40, 80 and 120 feet, respectively.  We sample three depths because the benthic communities are expected to vary by depth due to iceberg scouring and other processes. One of the limitations of our study is that 120 feet is at, or near, the deepest depth USAP divers are allowed to dive so we cannot monitor at deeper depths. 

Sampling Transecdts
Our marine sampling transects

The divers will have quite different amounts of time they can remain on the bottom and sample depending on the depth that they sample. At the deepest sites, typically divers will only have 10 minutes of time to work; therefore, it can take two dives to complete the sampling at each of the 120 foot sites. At the 40 and 80 foot sites, the bottom time is longer and a single diver can typically accomplish all that is necessary.  Rob and Steve typically work together on the deepest sites, Terry Palmer will do the intermediate depth and Martin will do the shallow as well as do any other work required on the intermediate as the diver at the shallow depth can have nearly 80 minutes to work.

At each station, the B-518 team collects the following

sampling tubes
Your commentator holding a small (yellow) and large (red) sampling core

A dive bucket
A dive bucket loaded with cores

Once the divers collect the sediment cores and animals as well as take photographs of the sites, the samples are brought to the surface in dive buckets – modified standard five gallon buckets that are lowered into and out of the water using a “down line.” Once at the surface the cores and animals are processed, usually by Terry and Steve.

Because the A and D transects are located in areas with hazardous materials, the type of diving used by the project is called surface supply diving where air is supplied via a hose (the umbilical) to a single diver.  Your commentator is responsible for feeding the umbilical cord that supplies air and communication to the divers. Mary is tasked with helping Terry and Steve and cleaning the sample tubes for use at the next site.

It is a peaceful wait while the divers are collecting the samples. We can hear their breathing as they are in constant communication...it can put some of us to sleep - right Steve?

Mary waiting
Mary sitting on the cooler we use to transport samples back to the lab

Steve waiting
Steve in his usual place in the dive locker. You can see the sampling jars on the bench waiting to be filled.

Once the samples have been returned to the lab, the sediments are prepared for shipment back to the States for analysis. Researchers at Texas A&M University-Corpus Christi perform the benthic infauna and toxicity analysis while investigators at GERG at Texas A&M University College Station work on the geochemistry. We also clean all of our sampling equipment so it is ready to go at the next site.

Well our first day of diving was a success.  We collected samples at all three sampling sites at our control transect. Rob and Steve collected the deep site in the morning, while Terry and Martin were able to successfully follow up in the afternoon.  We could not have asked for a better first day of diving.

It took a site or two, but your commentator was able to coil and uncoil the umbilical like a seasoned pro!