UH Hilo researchers find high bacteria levels at six popular coastal spots in Hilo

The researchers discovered staph and fecal indicator bacteria were roughly 6–78 times higher at beaches with freshwater discharge than at those without.

Maria wading out into the water holding a green bucket.
Maria Steadmon collects water samples at Onekahakaha Beach Park. (Photo: Melia Takakusagi)

By Susan Enright.

The accidental wastewater release that sent hundreds of thousands of gallons of partially treated effluent into Hilo Bay last week adds to the history of the area as a coast often teeming with bacteria.

Faculty and student researchers based at the Department of Marine Science at the University of Hawaiʻi at Hilo have been testing the waters in Hilo for years, consistently finding harmful bacteria, including staph and fecal indicator bacteria or FIB.

Lynn Morrison pictured
Lynn Morrison
Tracy Wiegner
Tracy Wiegner
Marie Steadmon pictured.
Marie Steadmon

A recently published study, “Detection and modeling of Staphylococcus aureus and fecal bacteria in Hawaiian coastal waters and sands” (Water Environment Research, May 2024), led by UH Hilo marine science alumna Maria Steadmon, presents water quality data from six popular spots at and near Hilo bay. Results of the multi-student and faculty project, conducted between the years 2016-2019, show staph in water and sand at the Hilo beaches, following a dismal trend.

Steadmon is a former UH Hilo Vulcan softball player who received her doctoral degree in marine science from UH Mānoa and is finishing up some postdoctoral research this summer. Come September, she will be taking a full-time position at the Hawaiʻi Department of Health’s State Laboratory Division. The DOH division conducts laboratory testing in support of environmental and public health programs statewide.

UH Hilo faculty researchers on the recently published water quality project are Tracy Wiegner, professor of marine science and expert in coastal water quality throughout Hawaiʻi Island, and Lynn Morrison, professor of anthropology. Morrison helped the research team develop the survey that was used to assess how the beaches are used by people, whether the beachgoers ever had a staph or MRSA infection that they thought was associated with their beach use, what the community could do to help educate people about risk of infection from beach use, and any other concerns or observations they’ve had relative to staph infections.

Faculty co-authors from UH Mānoa are Assistant Professor Kiana Frank and Associate Professor Matthew Medeiros, both from the Pacific Biosciences Research Center. (Frank was Steadmon’s PhD advisor.)

Other UH Hilo alumni who worked on the project collecting data over the years while students at UH Hilo are marine science major Mikayla Jones, who is now a medical doctor; biology major Melia Takakusagi, who recently received her medical doctor degree from the UH Mānoa John A. Burns School of Medicine; Louise Economy, who graduated from the tropical conservation biology and environmental science master’s program; and several students who participated in the Pacific Internship Programs for Exploring Science including Jazmine Panelo, Tyler Gerken, Carmen Garson-Shumay, Amy Olson, Adel Sharif, and Leilani Sablan.

The findings

The authors of the study say that microbial pollution of recreational waters leads to millions of skin, respiratory, and gastrointestinal illnesses globally. But, they point out, even though fecal indicator bacteria (FIB) are monitored to assess recreational waters, they may not reflect the presence of Staphylococcus aureus, a global leader in bacterial fatalities.

Since many community-acquired staph infections are associated with high recreational water usage, the study measured and modeled S. aureus, methicillin-resistant S. aureus (MRSA), and FIB (Enterococcus spp., Clostridium perfringens) concentrations in seawater and sand at six beaches in Hilo over 37 sample dates from July 2016 to February 2019 using culturing techniques.

Aerial of Hilo Bay
Hilo Bay. (Photo: Hollyn Johnson/UH Hilo)

The researchers discovered S. aureus and FIB concentrations were roughly 6–78 times higher at beaches with freshwater discharge than at those without.

“This may be due to the fact that not only humans can carry staph but animals as well,” says Steadmon in an interview with Hawaiʻi Public Radio. “We both can shed the bacteria in the soil and that can be washed into streams and the watershed and then discharged into the coast.”

In the recently published Hilo study, seawater concentrations of Enterococcus spp. were positively associated with MRSA but not S. aureus. Elevated S. aureus was associated with lower tidal heights, higher freshwater discharge, onsite sewage disposal system density, and turbidity.

The authors go on to say that regular monitoring of beaches with freshwater input, utilizing real-time water quality measurements with robust modeling techniques, and raising awareness among recreational water users may mitigate exposure to S. aureus, MRSA, and FIB.

Susan Enright is a public information specialist for the Office of the Chancellor and editor of UH Hilo Stories. She received her bachelor of arts in English and certificate in women’s studies from UH Hilo.

Share this story