ORIGINAL RESEARCH article
Front. Mar. Sci.
Sec. Marine Pollution
Volume 12 - 2025 | doi: 10.3389/fmars.2025.1634234
Variability in contamination of submarine groundwater discharge into West Hawaiʻi coral reefs
Provisionally accepted
- Arizona State University, Tempe, United States
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Sewage pollution is a global threat to coastal ecosystems and amplifies the negative effects of climate change on coral reefs. Submarine groundwater discharge (SGD) is a major transport pathway for this land-based pollution; however, underlying drivers of SGD water quality are poorly understood, especially for tropical ecosystems. This study combines airborne mapping, field sampling, and statistical modeling to identify locations along the West Hawaiʻi coastline where SGD is contaminated with sewage based on elevated levels of the fecal indicator bacteria Enterococcus and land cover characteristics associated with variability in contamination. Water samples were collected from 47 shoreline locations along the West Hawaiʻi coastline at locations of previously mapped submarine groundwater discharge. The resulting landscape-scale statistical model was applied to all mapped SGD point locations to identify areas highly susceptible to contamination in this coastal groundwaterconnected system. The model predicted that SGD delivers sewage-contaminated groundwater to multiple coral reefs along the West Hawaiʻi coast, and that contaminated sites are associated with both built-up land cover near the shoreline and the abundance of upstream on-site sewage disposal systems. Mitigation of sewage pollution will require the prevention of numerous point sources from cesspools, septic leach fields, and other sources.
Keywords: fecal indicator bacteria, submarine groundwater discharge, Sewage, Hawaiʻi, coastal development, coral reef
Received: 23 May 2025; Accepted: 31 Jul 2025.
Copyright: © 2025 Hondula, Martin and Asner. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Kelly Hondula, Arizona State University, Tempe, United States
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