Limu belongs to the algae family — but in terms of its role in the environment, it acts like a sponge and sucks up nutrients and chemicals from the surrounding waters.
One of these nutrients is nitrogen, which can turn up in coastal waters due to fertilizer runoff and sewage.
The Maui Nui Marine Resource Council has been collecting limu to monitor Maui’s coastlines for the past several years. Funding from Maui County’s Environmental Protection & Sustainability Division has enabled the nonprofit to expand from South Maui to the North Shore. Sampling in West Maui is planned for this month.
The sampling process is low-tech. Volunteers scramble over rocks and pick the tips off limu. They put the samples on ice and bring them back to the “lab” – aka science director John Starmer's kitchen.
Starmer recently spoke with The Conversation about the work. Researchers found high levels of nitrogen on Maui's North Shore in 2010. Starmer wanted to see if anything had changed.
To read the test, click here.
This story aired on The Conversation on July 7, 2025. The Conversation airs weekdays at 11 a.m.
