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Acidifying Waters Inspire Young Naturalist’s Investigation

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George measured the heart rates of grass shrimp to observe how the acidification of water affected the organisms. 
Photo courtesy of George.

Growing up in the Chesapeake Bay watershed, 14-year-old George was always attentive to its aquatic life. When he learned the waters were acidifying, George wondered how it would affect aquatic organisms.

He decided to measure the effects of changing water acidity, salinity, and temperature on grass shrimp, Palaemonetes pugio, using their heart rates as a measure of their metabolic oxygen consumption. For his investigation, which is described at length in his essay, The Effects of pH, Salinity, and Water Temperature on Palaemonetes pugioGeorge received a 2011 Young Naturalist Award.

Water acidification occurs when carbon dioxide dissolves in water and lowers the pH level. To monitor the effects of this process, George first collected grass shrimp from the York River in Virginia. Converting a room in his family’s home into a laboratory, George conducted a series of tests in which he altered the pH, salinity, and temperature of the water and measured the shrimps’ average heart rate. To account for the differences in size, George measured the length of each shrimp and calculated heartbeats per millimeter of length.

George’s results showed that the shrimps’ heart rates did lower significantly in more acidic waters. And when the water temperature rose, so did the organisms’ heart rates. However, he did not find any major differences in the shrimps’ heart rates at varying salinities.

The young naturalist’s determination to take shrimp size into account led to another finding: the larger shrimps had lower heart rates regardless of changes in the water. George suggests future research should include calculations of heartbeats per millimeter of length in any conclusions about environmental effects on the animals’ metabolic processes. “This will serve to remove the effects of length on heart rate when varying other parameters such as water temperature, salinity and pH,” George writes in his essay. His study adds to an ever-growing body of knowledge on the effects of changing climate on water and aquatic organisms.

The Young Naturalist Awards is a nationwide, science-based research contest for students in grades 7 through 12 presented by the Museum. To learn more and to submit your own project, visit The deadline for the 2012 contest is March 9, 2012.

The Young Naturalist Awards are proudly supported by Alcoa Foundation.