Antarctic fish have adapted over millennia to survive in the freezing temperatures of the Southern Ocean but in doing so have lost their ability to grow at rates seen in their warmer water cousins. Researchers have now discovered the cellular causes of this crucial difference between Antarctic and warm water fish.
The findings of the collaboration between the British Antarctic Survey and University of Plymouth have been published this week in the journal Royal Society Open Science.
Researchers examined two species of fish: the Antarctic spiny plunderfish and the common blenny. They found that when grown in the same temperature water, the Antarctic fish consumed around 20% less food than the species from temperate waters and grew at about half the rate. Additionally, Antarctic fish were shown to make proteins at a much lower rate than warmer water species. As a result, the ability of Antarctic fish to translate new proteins into physical growth was drastically reduced.
Scientists already knew that the cells of Antarctic fish have evolved to function in ways that are optimal for cold water conditions. These new findings though suggest that a trade-off for cells functioning optimally at polar water temperatures has been a greatly reduced ability to grow as efficiently, or rapidly, as warmer water fish.
Professor Lloyd Peck, lead physiologist on animal adaptations in extreme environments from the British Antarctic Survey, said: “There is unexpectedly high biodiversity on the seabed in Antarctica, with estimates of around 20,000 species living there. So far all of the species studied have great problems making proteins and it seems this is a ubiquitous constraint on life at low temperature. Adaptations such as this might make life easier in an environment with constant low temperatures, but they also appear to reduce abilities to survive in changing environments, which makes the future prospects for many Antarctic marine species bleak.”
The study is the first of its kind to assess how Antarctic fish make and store protein as growth compared to those from temperate waters. It also provides one of the largest comparative studies of protein metabolism, growth and food consumption in fish across a wide range of biologically relevant habitat temperatures.
Dr Keiron Fraser, Lecturer in Marine Conservation at the University of Plymouth and the study’s lead author, said: “Antarctic fish are highly thermally constrained and cannot live long-term at temperatures much above those that they currently inhabit. In contrast, many temperate species are more tolerant of a wide range of temperatures as they often inhabit extensive latitudinal ranges. Our data shows that the rates of growth and protein metabolism in an Antarctic species are significantly lower than in the temperate species, even when held at the same water temperature. As ocean temperatures increase with global warming, it is a timely reminder of the differences in species that have evolved to live at widely different temperatures.”
The full study, Life in the freezer: protein metabolism in Antarctic fish by Fraser, K., Peck, L., Clark, M., Clarke, A., and Hill, S., is published in the Royal Society Open Science.