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The 2007 Antarctic field season at Palmer Station was very productive! During January, our five-person team conducted laboratory and field studies on the stress tolerance of arthropods of the Antarctic Peninsula. Unlike previous field seasons, two members of our team remained at Palmer Station until mid-March. This extended season allowed us to continue several long-term laboratory projects and to better document seasonal changes associated with the approaching winter.
Once again, we recovered several temperature loggers that had been deployed in Belgica microhabitats. During summer months (January and February), it was not uncommon for larvae to experience maximum temperatures of >20°C and temperature changes of 15-20°C in a single day. On the other hand, larvae also experienced subzero temperatures during the summer months! During the winter (April - October), microhabitat sites typically remained between 0 and -5°C, thanks to a thermal buffer of snow and ice.
November and December 2006 were extremely warm around Palmer Station. Because it was so warm, the snow melted earlier and larval microhabitat sites warmed up faster than in 2005. In addition, the warming likely caused the early emergence of adult Belgica. We found very few adults by the time we started collecting in early January 2007.
Desiccation Tolerance and Water Balance
Desiccation stress was again a major focus of our Belgica research during 2007. We had previously documented the tremendous desiccation tolerance of Belgica (larvae tolerate the loss of ~70% of their body water), but wanted to further characterize the molecular and physiological responses behind such extreme tolerance. We collected RNA and protein samples from larvae and will analyze them in our home laboratories at Miami University and Ohio State University for changes occurring during dehydration.
In addition, we assessed the water balance and desiccation tolerance/resistance in another Antarctic arthropod, the springtail Cryptopygus antarcticus. Samples were also collected from Cryptopygus to assess physiological changes occurring during dehydration.
In early 2006, we documented the ability of larval Belgica to dehydrate at subzero temperatures (cryoprotective dehydration). This year, we were interested in comparing the metabolic costs and implications of freezing versus dehydration at subzero temperatures. In other words, which overwintering strategy – freezing or dehydration – is better? Samples have been collected for measurement of metabolites, but await analysis back at our home laboratories. In addition, we collected protein samples to assess changes in protein expression during freezing and dehydration.
As larval Belgica may periodically be submerged in seawater, we again focused on osmoregulation and salinity tolerance. Samples were collected to analyze the molecular and physiological response of larvae to a short seawater acclimation. In addition, we examined how seawater acclimation can improve tolerance of freezing, heat shock, and desiccation. We found that acclimation to seawater results in an increased tolerance of other environmental stressors!
Antioxidant Defense and Reactive Oxygen Species
In 2006, we began a project focusing on the antioxidant defense systems of Belgica. Larvae can be exposed to a variety of environmental stressors (freezing, heat, desiccation, UV) that may result in the formation of potentially damaging oxygen radicals (reactive oxygen species). We found that larvae possess an extremely high antioxidant defense capacity to combat reactive oxygen species, and thereby prevent cellular damage.
This year, we collected adult Belgica to assess their antioxidant defenses. We expect that since the adults only live for 10-14 days, and are exposed to fewer stresses, they will have a weaker defense system than the larvae.
As you can see, it was a very busy couple of months in our Antarctic laboratory and we have a lot more work to do at home! We hope the completion of these projects will provide new insights into how Belgica can survive the harsh environment of the Antarctic Peninsula. For more information on our work, or learn about new results, check our Publications page for technical articles.