(p. A4) . . ., a new study suggests for the first time that high water temperatures can cause memory loss in reef fish, and even render them unable to learn at all.
. . .
The researchers designed a maze with a reward in one hallway. For about two weeks before maze training began, three groups of fish were gradually exposed to different temperatures: 28to 28.5 degrees Celsius for the control group, 30to 30.5 Celsius for the second, and 31.5 to32 Celsius for the third.
. . .
The researchers spent five days training the fish to navigate the maze and to associate a blue tag with their reward. Five days after training ended, they tested the fish to see which groups could remember how to find the tag, and their reward, in the maze.
The control group did well, quickly remembering how to reach the reward in the maze. But fish in even the moderately hot group didn’t fare as well. Although they learned to navigate the maze quickly during training, five days later, all evidence of their experience had vanished. In earlier experiments, Dr. Luchiari found that damselfish could remember experiences for at least 15 days, so an inability to remember the maze after only five was striking.
Fish in the hottest group failed to learn the maze at all, taking roughly the same amount of time to navigate it throughout the whole experiment.
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(Note: ellipses added.)
(Note: the online version of the story has the date Aug. 23, 2023, and has the title “Damselfish in Distress: Warmer Seas Might Be Clouding Their Brains.”)