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UH Mānoa Researchers Look Into ʻOpihi Growth Patterns

Kanoe Morishige
UH News
ʻOpihi cling to rocks, helmet urchin or haʻukeʻuke in background.

Researchers from the University of Hawaiʻi at Mānoa are studying the growth patterns of ʻopihi by looking at microscopic details on their shells.

Researchers used a powerful microscope-like instrument called secondary-ion mass spectrometry (SIMS).

They used the SIMS methodology to study three ʻopihi shells — two of them were modern, collected along the south shore of Oʻahu in 2018 summertime, and one was historic and donated by the Bishop Museum.

"For each of those shells, imagine cutting them in half and being able to look from the side," Erik Franklin, associate professor at the UH Mānoa School of Ocean and Earth Science and Technology, said.

"If you were to use a microscope, you would see these little lines that show up," Franklin said. "These represent the ʻopihi laying down the growth of its shell. If you can find a way to tie them to some other environmental feature, you can understand something about when that growth occurs, and how fast that animal is growing."

This data will help fisheries sustainably collect ʻopihi.

Although they are not endangered, Franklin said studies on Hawaiʻi fisheries from one hundred years ago show that ʻopihi captures were much higher than they are today.

Zoe Dym is a news producer at Hawaiʻi Public Radio.
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