Students collect seaweed and water samples along the Puakō coastline for detection of sewage pollution

For conservation efforts to be effective and long lasting, partnerships between local communities and researchers are necessary, says Tracy Wiegner, professor of marine science at the University of Hawaiʻi at Hilo who is part of a research team studying ocean water quality in South Kohala on Hawaiʻi Island. In particular, she says, local communities must see a need for conservation activities and desire for them to occur. It is crucial that they participate in developing these projects to meet their community’s desired outcomes, and are committed to the efforts required for long-term success.

For a long time, these types of partnerships were overlooked by university and state and federal agencies, but they are now recognized as essential for any conservation project to be successful.

Wiegner is working on this new type of community-researcher partnership in collaboration with Steve Colbert, assistant professor of marine science, and Jim Beets, professor of marine science. The research team is investigating sewage pollution in nearshore waters off Puakō, an ocean-side community in South Kohala.

Wiegner, her collaborators, and students are documenting the presence of sewage through bacterial, seaweed and water quality measurements.

“The first step of the project was to document that there was a sewage pollution problem,” Wiegner explains. Documentation is essential to establish that a problem exists, she says, and it allows the community to decide, first, if they want to do something about it, and second, to investigate potential solutions.

Household waste present in nearshore waters

To date, results from the project demonstrate that waste from homes in Puakō is present in the nearshore waters. The most telling piece of the research is results from the dye tracer studies where dye was washed down sinks or added to cesspools. Colbert detected the dye in 72 hours in seeps along the shoreline in front of the houses. Wiegner says these results “really demonstrate the connection between the homes and the nearshore waters. You couldn’t ask for more concrete evidence than that.”

Other results have shown that the groundwater upslope of Puakō has much lower nutrient concentrations than the groundwater that enters the ocean. This suggests that there is some source of nutrients at Puakō, possibly sewage.

Coincidently, nearshore seaweed at Puakō has nitrogen values similar to those of sewage. Together, these data suggest that indeed these extra nutrients are from human waste.

Research this summer will further examine how far offshore the sewage can be detected and whether it is coming up through the reef and directly impacting coral.

For the full story, visit the UH Hilo Stories website.