Environment

Study finds that eddies provide upwelling nutrients and improve productivity around the Hawaiian Islands

Credit: Troy Squillaci from Pexels

Other than colorful coral reefs and diverse coastal ecosystems, the Pacific waters surrounding the Hawaiian Islands are relatively devoid of marine life and have low biological productivity. A new study published by oceanographers at the University of Hawai’i (UH) Mānoa shows that eddies on the leeward side of the Hawaiian Islands can provide nutrients not only locally but also on the other side of the archipelago, encouraging phytoplankton blooms. showed. A microscopic plant that lives on the surface of the ocean.

The study, published in JGR Oceans, was selected as a featured article by the American Geophysical Union Editorial Board.

“These eddies are known to affect local biological productivity, but our research shows that nutrients upwelled by these eddies can be used against background currents to “We found that it could be transported into the environment,” said Kate Ferroy, lead author of the study and a research fellow at the Kamihiro Graduate School. He is also a doctoral candidate in the Department of Oceanography at the University of Manoa School of Ocean and Earth Science and Technology (SOEST). “These results demonstrate how eddies can remotely and broadly impact productivity around the Hawaiian Islands.”

Unreported flowering, trailhead

Nutrient availability is crucial for phytoplankton, which form the basis of the marine food chain. The waters around Hawaii are typically very nutrient-poor, limiting growth. Ferroy and co-authors Brian Powell and Tobias Friedrich used satellite data to observe previously unreported phytoplankton blooms off the northern coast of some of the Hawaiian Islands.

The researchers used a computer model of the region to simulate the ocean around Hawaii’s main island and conducted a series of experiments to determine the nutrient sources that cause these anomalies. Initially, they expected to uncover the mechanism that causes local upwelling north of the island chain. The model accurately reproduced the bloom event. However, the results showed that the blooms were caused by nutrients supplied by upwelling eddies about 160 miles away.

“Our study reveals that nutrients from the eddies are transported to the ocean below the sunlit layer around the island, where local upwelling can trigger phytoplankton blooms. I did,” Ferroy said. “This study identifies a new mechanism that can deliver nutrients around Hawaii.”

These blooms are important events for the region’s biological productivity, or productivity transmitted through the food chain, and can impact fisheries near Hawai’i. This same mechanism may influence productivity around islands in other nutrient-poor areas. ”

Further information: K. Feloy et al., “Remote effects of cyclonic eddies on productivity around mainland Hawaii,” Journal of Geophysical Research: Oceans (2024). DOI: 10.1029/2023JC020670

Provided by University of Hawaii at Manoa

Citation: Eddies provide upwelling nutrients to boost productivity around Hawaiian Islands, study (October 31, 2024) available at https://phys.org/news/2024-10-eddies Retrieved October 31, 2024 from -upwelled-nutrients-boost-productivity. html

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