Scientist follows in the scientific footsteps of Shackleton expedition
Posted March 28, 2014
When people think of Shackleton’s expeditions in Antarctica they probably think of bravery, determination and adventure. Well, I think of algae.
Members of Shackleton’s Nimrod Expedition of 1907-1909 collected freshwater algae samples at many of the places they visited, including Cape Royds on Ross Island. These collections became the basis of some of the first scientific descriptions of freshwater algae in Antarctica.
During the 2013-14 fields season, I, in collaboration with Adrian Howkins , an environmental historian from Colorado State University , followed the expedition’s footsteps and collected samples from some of the same bodies of water more than 100 years later.
Why algae? As part of my Master’s Degree in Environmental Studies at the University of Colorado, Boulder , I study a particular type of algae called diatoms. Diatoms are unicellular organisms encapsulated by silica that photosynthesize and live anywhere there is fresh water on the harsh landscapes of Antarctica.
Their glass-like shells make it possible to identify individual cells down to a species level using a microscope, a process that is much more difficult in other types of algae. This detailed identification allows for a better understanding of community structure and ecology of diatoms.
Lucky for me, and everyone else who studies diatoms in this region of Antarctica, there are just over 40 species of diatoms. This number is just about perfect for different kinds of analyses. Analyzing 100 or more species would be very time consuming, and perhaps difficult to resolve small variations in communities. Communities with too few species could be dominated by only one or two species.
The samples I’ve collected could resolve some lingering taxonomic questions. The first descriptions by the early explorers included careful drawings, and our ability to image diatoms in great detail has improved dramatically in 100 years. The light microscopy has improved tremendously, and we can also visualize diatoms in greatest detail with a scanning electron microscope. So descriptions of species can now be more detailed and similar species can be resolved.
Our intent in returning to the sites sampled before was to determine if the same species are still abundant, and to obtain samples to describe these species more precisely.
Along with the samples I collected at Cape Royds, where Shackleton’s Nimrod expedition hut still stands, I also collected from ponds all over the McMurdo Dry Valleys .
This past season I spent over two months in the field, working as part of the McMurdo Long Term Ecological Research stream team. Our work involved measuring stream flow, collecting water samples and generally monitoring about 20 streams (and one river) across the Dry Valleys. These measurements have been going on for more than 20 years now, forming a long-term record. [See previous article — Ongoing experiment: McMurdo LTER program marks 20 years of groundbreaking research.]
I was the resident algae expert this season, making collections and analyzing algae samples from these streams, adding to the long-term record. Diatoms have been studied extensively in the streams of Dry Valleys, and the LTER maintains a database of diatom data from various Antarctic regions.
When I had an opportunity during my stream team duties, I visited many ponds all over the Dry Valleys and collected water chemistry and algae samples. Together, with my collections from Cape Royds, I obtained a great range of variability in conditions such as pH, nitrogen content, other nutrient content, and salinity.
Even ponds and small lakes from Cape Royds ranged from very fresh, with low nitrogen levels, to quite saline and rich in nitrogen. Analyzing relative abundances of communities of these different ponds might tell us a lot about diatom ecology.
Depending on how diatoms are transported by the wind, geography could play a major role as well, with communities being more similar if they are closer geographically, even if the water chemistry is quite different.
Time will tell what scientific lessons I will learn from my efforts in Antarctica, but I had an experience of a lifetime working there and had a chance to walk the paths of great explorers from many years ago.
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