Antarctic fish have adapted over millennia to survive in the freezing temperatures of the Southern Ocean.
However, in doing so, they lost their ability to grow at the rates seen in their warmer-water cousins, even when they are now kept at the same water temperature, according to a new study.
The research, led by scientists from the University of Plymouth and the British Antarctic Survey, focused on two species – the Antarctic prickly poodle (Antarctic Harpagifer) and shanny (Lipophyrs pholis), also known as common blenny.
Antarctic fish consumed about 20% less food than temperate-water species and grew about half the size, even when the two ecologically similar species were kept at the same water temperature.
These new findings show that fish living in Antarctic water temperatures have dramatically increased the amount of cellular machinery they have to make proteins – but still cannot make proteins at the same rate as species in warmer waters. warm – while the rates at which polar and temperate fish break down protein is very similar
In turn, this means that in Antarctic fish, the ability to translate new proteins into physical growth has been significantly reduced.
As a result, the researchers say, it seems likely that an evolutionary trade-off for being able to survive polar water temperatures has been a greatly reduced ability to grow as efficiently or quickly as warmer-water fish.
This in turn has important implications for exposure to predation and the number of years required to reach sexual maturity.
Posted in Royal Society Open Sciencethe study is the first of its kind to assess how Antarctic fish make and store protein as they grow compared to those in temperate waters.
It also provides one of the largest comparative studies of protein metabolism, growth and food consumption in fish over a wide range of biologically relevant habitat temperatures.
Dr Keiron Fraser, senior lecturer in marine conservation at the University of Plymouth and lead author of the study, said: “Antarctic fish are under high thermal stress and cannot live long term. at temperatures well above those they currently inhabit. In contrast, many temperate species are more tolerant of a wide range of temperatures because they often inhabit wide latitudinal ranges. Our data show that growth and protein metabolism rates in an Antarctic species are significantly lower than in temperate species, even when kept at the same water temperature. As ocean temperatures rise with global warming, it’s a timely reminder of the differences between species that have evolved to live at vastly different temperatures. If Antarctic fish are increasingly exposed to higher temperatures, this will have implications for their survival, as well as effects on many critical physiological processes, including growth.
Professor Lloyd Peck, Senior Physiologist on Animal Adaptations to Extreme Environments at the British Antarctic Survey, added: “There is a surprisingly high biodiversity on the Antarctic seafloor, with estimates of around 20,000 species live there. So far, all species studied have major problems making proteins and it seems to be a pervasive constraint for life at low temperatures. There are many other unique adaptations among Antarctic marine species, such as 16 species of fish which are the only animals whose spine does not have red blood cells or hemoglobin to carry oxygen around them. bodies, or giant spider crabs thousands of times heavier than the largest in temperate zones. In addition to problems with protein manufacturing, many of these other adaptations might make life easier in an environment with consistently low temperatures, but they also appear to reduce survivability in changing environments, making them dark. future prospects for many Antarctic marine species. .”
Reference: “Life in the Freezer: Protein Metabolism in Antarctic Fishes” March 8, 2022, Royal Society Open Science.