By Akari Miki
As the temperatures of the oceans increase, coral reef fish have two choices – to adapt or to migrate to colder waters. According to past research, they can tolerate waters that are two to four degrees Celsius higher than the normal summer temperatures. But when given the opportunity, do they migrate? In their experiments on the blue-green damselfish, marine biologists of the University of Texas at Austin found that they moved to colder waters. There are two possible explanations for this behavior. When adapting, the fish risk their ability to cope with stress, grow, and reproduce, and they can better maintain their physiological processes by migrating. Furthermore, sea temperatures have been rising quickly; by the end of the twenty-first century, sea temperatures are expected to rise by two to four degrees Celsius. In terms of evolution, it has taken about one million years for the fish to expand their heat tolerance by one degree Celsius, so this rate of evolution cannot overcome the rate of global warming.
However, despite their possible preference, migration is challenging for the blue-green damselfish. They cannot travel more than sixty feet from their coral reefs, and the coral reefs cannot travel to cooler latitudes as quickly as the rate of temperature increase. Therefore, the fish may resort to living in deeper waters while facing severe conditions. After discovering the fish’s possible preference to migrate, the marine biologists seek to test their hypotheses, further investigating the challenges the fish face when adapting and migrating.
University of Texas at Austin. (2016, October 5). As oceans warm, coral reef fish might prefer to move rather than adapt. ScienceDaily. Retrieved October 15, 2016 from www.sciencedaily.com/releases/2016/10/161005135216.htm