Coral skeleton δ15N as a tracer of historic nutrient loading to a coral reef in Maui, Hawaii

Joseph Murray; Nancy G. Prouty; Sara E. Peek; Adina Paytan

doi:10.1038/s41598-019-42013-3

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Coral skeleton δ15N as a tracer of historic nutrient loading to a coral reef in Maui, Hawaii

Joseph Murray·Nancy G. Prouty·Sara E. Peek·Adina Paytan

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Abstract

Excess nutrient loading to nearshore environments has been linked to declining water quality and ecosystem health. Macro-algal blooms, eutrophication, and reduction in coral cover have been observed in West Maui, Hawaii, and linked to nutrient inputs from coastal submarine groundwater seeps. Here, we present a forty-year record of nitrogen isotopes (δ 15 N) of intra-crystalline coral skeletal organic matter in three coral cores collected at this site and evaluate the record in terms of changes in nitrogen sources. Our results show a dramatic increase in coral δ 15 N values after 1995, corresponding with the implementation of biological nutrient removal at the nearby Lahaina Wastewater Reclamation Facility (LWRF). High δ 15 N values are known to be strongly indicative of denitrification and sewage effluent, corroborating a previously suggested link between local wastewater injection and degradation of the reef environment. This record demonstrates the power of coral skeletal δ 15 N as a tool for evaluating nutrient dynamics within coral reef environments.

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Source-reported bounding extent: 20.932923344761708° to 20.94877529374215° latitude; -156.69604539871216° to -156.6832995414734° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Joseph Murray, Nancy G. Prouty, Sara E. Peek, Adina Paytan. 2019-04-03. Coral skeleton δ15N as a tracer of historic nutrient loading to a coral reef in Maui, Hawaii. https://doi.org/10.1038/s41598-019-42013-3

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