Variability in contamination of submarine groundwater discharge into West Hawai‘i coral reefs

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 land-based pollution, but underlying drivers of SGD water quality are poorly understood, especially in...

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Main Authors: Kelly L. Hondula, Roberta E. Martin, Gregory P. Asner
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-08-01
Series:Frontiers in Marine Science
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fmars.2025.1634234/full
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author Kelly L. Hondula
Roberta E. Martin
Roberta E. Martin
Gregory P. Asner
Gregory P. Asner
author_facet Kelly L. Hondula
Roberta E. Martin
Roberta E. Martin
Gregory P. Asner
Gregory P. Asner
author_sort Kelly L. Hondula
collection DOAJ
description 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 land-based pollution, but underlying drivers of SGD water quality are poorly understood, especially in nearshore coral reef ecosystems. We combined airborne mapping, field sampling, and statistical modeling to identify locations along the West Hawai‘i Island coastline where SGD is contaminated with sewage. Water samples collected from 47 distributed shoreline SGD locations were assayed for fecal indicator bacteria. A geostatistical model was used scale from field to regional levels at more than 1000 mapped SGD point locations to derive a geographic understanding of areas highly susceptible to contamination. We estimate that SGD delivers sewage-contaminated groundwater to at least 42% of reefs in West Hawaiʻi. Subsequent analyses indicate that contaminated points are associated with infrastructural build-up near the shoreline and an abundance of inland on-site sewage disposal systems. Mitigation of sewage pollution will require the prevention of numerous point sources from cesspools, septic leach fields, and similar sources.
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spelling doaj-art-e5ad5d6fdd4f48dc9e79df1c4bc4177e2025-08-26T05:28:08ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452025-08-011210.3389/fmars.2025.16342341634234Variability in contamination of submarine groundwater discharge into West Hawai‘i coral reefsKelly L. Hondula0Roberta E. Martin1Roberta E. Martin2Gregory P. Asner3Gregory P. Asner4Center for Global Discovery and Conservation Science, Arizona State University, Hilo, HI, United StatesCenter for Global Discovery and Conservation Science, Arizona State University, Hilo, HI, United StatesSchool of Ocean Futures, Arizona State University, Hilo, HI, United StatesCenter for Global Discovery and Conservation Science, Arizona State University, Hilo, HI, United StatesSchool of Ocean Futures, Arizona State University, Hilo, HI, United StatesSewage 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 land-based pollution, but underlying drivers of SGD water quality are poorly understood, especially in nearshore coral reef ecosystems. We combined airborne mapping, field sampling, and statistical modeling to identify locations along the West Hawai‘i Island coastline where SGD is contaminated with sewage. Water samples collected from 47 distributed shoreline SGD locations were assayed for fecal indicator bacteria. A geostatistical model was used scale from field to regional levels at more than 1000 mapped SGD point locations to derive a geographic understanding of areas highly susceptible to contamination. We estimate that SGD delivers sewage-contaminated groundwater to at least 42% of reefs in West Hawaiʻi. Subsequent analyses indicate that contaminated points are associated with infrastructural build-up near the shoreline and an abundance of inland on-site sewage disposal systems. Mitigation of sewage pollution will require the prevention of numerous point sources from cesspools, septic leach fields, and similar sources.https://www.frontiersin.org/articles/10.3389/fmars.2025.1634234/fullfecal indicator bacteriasubmarine groundwater dischargesewageHawai‘icoastal developmentcoral reef
spellingShingle Kelly L. Hondula
Roberta E. Martin
Roberta E. Martin
Gregory P. Asner
Gregory P. Asner
Variability in contamination of submarine groundwater discharge into West Hawai‘i coral reefs
Frontiers in Marine Science
fecal indicator bacteria
submarine groundwater discharge
sewage
Hawai‘i
coastal development
coral reef
title Variability in contamination of submarine groundwater discharge into West Hawai‘i coral reefs
title_full Variability in contamination of submarine groundwater discharge into West Hawai‘i coral reefs
title_fullStr Variability in contamination of submarine groundwater discharge into West Hawai‘i coral reefs
title_full_unstemmed Variability in contamination of submarine groundwater discharge into West Hawai‘i coral reefs
title_short Variability in contamination of submarine groundwater discharge into West Hawai‘i coral reefs
title_sort variability in contamination of submarine groundwater discharge into west hawai i coral reefs
topic fecal indicator bacteria
submarine groundwater discharge
sewage
Hawai‘i
coastal development
coral reef
url https://www.frontiersin.org/articles/10.3389/fmars.2025.1634234/full
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AT gregorypasner variabilityincontaminationofsubmarinegroundwaterdischargeintowesthawaiicoralreefs
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