A new study shows that when it comes to climate change, the simpler a marine organism is structured, the better.
Scientists from the Alfred Wegener Institute (AWI), Helmholtz Centre for Polar and Marine Research studied the relationships between the complexity of marine life forms and their ability to adapt to a warmer climate. They found that unicellular bacteria and archaea are able to live in hot, oxygen-deficient water, while more complex marine creatures reach their growth limits at a water temperature of 41 degrees Celsius.
Researchers know that marine creatures respond differently to increasing water temperature and decreasing oxygen content, but they wanted to know why that is.
“Why do bacteria, for example, still grow at temperatures of up to 90 degrees Celsius, while animals and plants reach their limits at the latest at a temperature of 41 degrees Celsius,” AWI study author Dr. Daniela Storch asked in a news release.
The answer is the cardiovascular system.
Dr. Storch and colleagues were able to show that this transport system was the first to fail as temperatures rose. Blood can only circulate through the body, supplying cells and organisms with oxygen, in certain temperatures. Beyond the threshold, the system fails and animals can only “sustain performance” for a short period of time.
In the study, they examined the hypothesis that complexity is the key that determines adaptability.
“That means: the simpler the structure of an organism, the more resistant it should be,” Dr. Storch explained.
That’s just what they found: the simpler the organism, the more heat-tolerant it was. The results also provide evidence that the body size of an organism plays an important role in adaptation limits — smaller organisms can survive at lower oxygen concentration levels and higher temperatures longer than the larger ones.
The next step is to examine the role that the complexity of a species plays for tolerance and adaptation to a third climate change factor: ocean acidification.
To learn more:
- Read the news release: The simpler, the more heat-resistant – scientists uncover the key to adaptation limits of ocean dwellers
- See the full study: Climate sensitivity across marine domains of life: Limits to evolutionary adaptation shape species interaction.
Copyright © 2014 by Marine Science Today, a publication of Marine Science Today LLC.