For centuries, scientists have used tree rings to understand past climates. Now, researchers are turning to an unexpected source for similar insights: the ears of fish. These small, hard structures, known as otoliths, act like personal diaries for fish, recording their age and experiences throughout their lives.
Otoliths are made of calcium carbonate and grow in layers, similar to tree rings. By analyzing these layers, scientists can determine a fish’s age, growth rate, and even the temperature of the water it lived in.
But the story doesn’t end there. Researchers have discovered that the chemical composition of otoliths can also reveal valuable information about a fish’s diet and energy expenditure. By studying the ratios of different isotopes (atoms with the same number of protons but different numbers of neutrons) in the otoliths, scientists can determine how much food a fish was consuming and how efficiently it was using that energy.
This information is proving to be invaluable in understanding how climate change is impacting marine life. As water temperatures rise, fish are forced to expend more energy to maintain their body functions. This can lead to decreased growth, reduced reproduction, and even death.
By studying otoliths, scientists can track these changes over time and gain a better understanding of how different species are responding to climate change. This knowledge can then be used to develop conservation strategies and help protect marine life from the harmful effects of a warming planet.