Global climate change and the Southern Ocean: How Antarctic fishes physiologicially respond to a changing environment from the cellular to the organismal level.

摘要

Studies have projected future changes in sea surface temperature and pCO2 levels will impact higher latitudes to a greater extent than temperate regions. For notothenioid fishes of the Southern Ocean, evolution in extremely stable, cold waters have resulted in several adaptations which have left these fishes poorly prepared for global climate change. I have analyzed the metabolic and cellular response of Trematomus bernacchii, Pagothenia borchgrevinki and Trematomus newnesi to a long-term, multi-stressor scenario relevant to the predicted changes in the Southern Ocean. By combining whole animal respirometry with cellular level analysis of energy allocation, osmoregulatory mechanisms and cellular damage, I aimed to determine if acclimation to increased sea surface temperature (4°C), increased seawater pCO2 levels (1000 microatm), or a combination of these two parameters result in energetic trade-offs and exacerbated cellular damage. The data suggest a synergistic relationship exists between elevated temperature and pCO2, as the combination of these variables further elevates metabolic rates and delays the acclamatory response. Overall, long-term acclimation to experimental treatments resulted in a novel discovery: despite evolving in the same environment and on the same time-scale, these three species of notothenioid differ in their physiological response to global climate change, and defend different biochemical pathways when confronted with a changing environment. While T. bernacchii, P. borchgrevinki, and T. newnesi all showed small acclamatory capacities, there appear to be energetic trade-offs associated with this acclimation, and overall, it may not be possible for energetic demands to be met over long time scales, which could result in long-term impacts to population numbers.