Researchers Return from Monitoring ʻOpihi in the Monument

Large blackfoot ʻopihi (ʻopihi makaiauli) line the shoreline; in the distance, the intertidal monitoring team checks for waves. Credit: Hoku Johnson/NOAA

On June 30, 2014, members of PMNM’s intertidal monitoring expedition returned having completed the sixth consecutive year of conducting research and monitoring activities within the rocky shorelines of Nihoa, Mokumanamana and French Frigate Shoals in the Northwestern Hawaiian Islands (NWHI).

Mapping the rocky shorelines on the remote islands involved walking, crawling, swimming, and at times clinging to rocks to count, size, and record all ʻopihi (Hawaiian limpet) around the islands. The data collected will be turned into spatial “heat maps” depicting ʻopihi abundance, size and species on each island, and small samples will be used in genetic analyses to examine rates of evolution.

Kanoe Morishige records data from a small boat while the intertidal monitoring team members count ʻopihi on the rocky shorelines of Papahānaumokuākea Marine National Monument. Credit: Hoku Johnson/NOAA

ʻOpihi, a prized food item in Hawaiʻi, is in serious decline in the main Hawaiian Islands. Scientists are trying to better understand spawning patterns, gene flow and the rate of evolution of the three ‘opihi species endemic to Hawaiʻi in order to conserve the species and manage shorelines near populated areas.

Monitoring and mapping ʻopihi in the Monument is important as the areas visited are relatively pristine and data collected will provide good baseline information to compare with data being collected in the more populated main Hawaiian Islands.

Early indications from improved genetic analyses of ʻopihi from the NWHI suggest that hybridization is occurring between the yellowfoot and blackfoot ʻopihi on Mokumanamana. This is significant because when a species pulls from two different gene pools, it may be more resilient against the effects of climate change and other disturbances.

While ʻopihi is a main focus of these expeditions, the team also monitors all invertebrates and limu (seaweed) in the intertidal zone, conducts observations of the weather and environment and conducts Native Hawaiian cultural protocol.

Makani Gregg records data while the team surveys the rocky shoreline during the 2014 Papahānaumokuākea Marine National Monument Intertidal Monitoring survey. Credit: Hoku Johnson/NOAA

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