Measuring ocean acidification impacts in the Southern ocean

For the past two months, a research team (B-199-M) led by Environment and Sustainability Program faculty member, Dr. Sean Place, has been deployed to McMurdo Station, Antarctica working to collect data on the physiological response of endemic fish species of the Ross Sea to a high CO2 environment.

They are currently in the first year of a three-year project focused primarily on members of the Nototheniidae family of fishes that possess a suit of unique physiological adaptations that allow them to exist at the edge of the freezing point of seawater (~ -1.9 C).

By measuring the physiological response of several closely related species of fish they hope to gain insight into the scope of their ability to adjust to a changing climate and the energetic costs of this adaptive capacity. The field team has spent several weeks making daily trips on the annual sea ice to reach highly productive sites near Cape Evans, the Del-bridge Islands, and the Ross Ice Shelf to collect several different species of fish for their experiments. They have employed rather diverse methods of collection, including jigging with small ice fishing poles at depths of 10-50m, to deployment of baited traps at depths of 400-700m, collecting 7 different species of fish and the occasional octopus!

Once back at McMurdo Station the fish are placed into acclimation tanks whose seawater chemistry and temperatures have been adjusted to mimic oceanic conditions laid out in the current IPCC predictions for the year 2100 with atmospheric CO2 levels nearing 1000 ppm. They are currently using a series of digital mass-flow controllers to precisely infuse seawater with CO2 gas mixtures in 1240L holding tanks located in the aquarium facilities of the Albert P. Crary Science and Engineering Center. Here they can acclimate fish anywhere from a few days to several weeks and measure basic physiological parameters such as changes in metabolic oxygen consumption.

The fully equipped laboratory space allows them to also conduct cellular based analyses of oxidative damage to macromolecules as well as changes in key metabolic pathways. Year two of this study will bring further investigation of changes at the molecular level, including changes in gene expression and energy allocation as well as organism level analysis of impacts on swimming performance. They are currently past the halfway point in their season and the austral summer is ramping up. With daily temperatures routinely climbing into the positive side of the scale, the sea ice is warming, melt pools are forming, cracks in the sea ice are becoming more active again, and thus the sea ice will soon be closed to science groups for travel.

This bitter sweet event marks a unique transition in the research population here at McMurdo, with a shift in focus from the marine realm to terrestrial and limnetic biology as well as an influx of geology and climate focused event groups. For them, this also marks the end of fish collection and the beginning of the big rush to collect as much data as they can before their departure in a little less than a month. With the end of their first field season in sight they can be comforted by the fact that not all the fun is over, after all, they still have hundreds of samples to analyze once back in the lab at USC, and there is always next year.

 

University of South Carolina, College of Arts and Sciences, 12 January 2012. Article.


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