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<p>In this study, we presents a comprehensive water quality findings from Norfolk Island dataset (2022–2024) under the Norfolk Island Water Resource Assessment (NIWRA). Sampling focused on both reference sites (Cascade, Duncombe, Anson, Ball Bays) and impacted areas such as (Slaughter Bay, Emily Bay, Cemetery Bay) where coral reef health has deteriorated. Monitored parameters which included temperature, dissolved oxygen, pH, salinity, turbidity, nutrients, metals, and ultra-trace organic contaminants, were measured under both baseline and post-rainfall conditions. Baseline sampling was conducted when no rainfall event greater than 20&#xa0;mm had occurred in the previous 1 to2&#xa0;weeks, while post-rainfall sampling followed events exceeding 20&#xa0;mm of precipitation within the prior 24 to48&#xa0;h, consistent with NIWRA classification criteria. Elevated nutrient levels, especially total nitrogen (TN) and total phosphorus (TP) ,and episodic spikes during turbidity were frequently observed in impacted sites following storm-driven runoff (Donova, Proc Natl Acad Sci USA 10:5351–5357,&#xa0;<CitationRef CitationID="CR1">2020</CitationRef>). Dissolved oxygen also fluctuated significantly in these areas, revealing episodic supersaturation (suggesting algal blooms) or localized oxygen depletion (Johnson, Sci Rep 11:23168,&#xa0;<CitationRef CitationID="CR5">2021</CitationRef>). Reference sites, despite the fact that they are generally more stable, were not fully exempt from discrete surges of nitrogen or periodic turbidity increases. By examining both typical baselines and acute runoff episodes, NIWRA dataset shows how terresterial nutrient inputs, sediment-laden stormwater, and restricted circulation can lead to short-lived but highly stressful water quality conditions for corals. Consistent measurements across multiple laboratories—supported by interlaboratory comparisons (QA/QC)—establish a robust framework for site-specific guideline development. Findings indicate that nutrient over-enrichment poses a more pressing risk than heavy metals, highlighting the need for targeted watershed management, erosion control, and enhanced wastewater treatment to protect Norfolk Island’s reefs. Continued monitoring, paired with long-term trend analysis, is recommended to detect emerging issues, fine-tune guideline thresholds, and guide adaptive coastal management strategies to safeguard reef ecosystems under changing environmental pressures.</p>

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Integrating baseline and runoff-driven variability to formulate site-specific marine water quality guidelines on Norfolk Island

  • 期刊论文

  • 发表日期：

    2025年11月21日

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  • Oumaima Bouanani,
  • Sara Sandabad,
  • Hassan MABCHOUR,
  • Moulay El Houssine EchChhibat

摘要

In this study, we presents a comprehensive water quality findings from Norfolk Island dataset (2022–2024) under the Norfolk Island Water Resource Assessment (NIWRA). Sampling focused on both reference sites (Cascade, Duncombe, Anson, Ball Bays) and impacted areas such as (Slaughter Bay, Emily Bay, Cemetery Bay) where coral reef health has deteriorated. Monitored parameters which included temperature, dissolved oxygen, pH, salinity, turbidity, nutrients, metals, and ultra-trace organic contaminants, were measured under both baseline and post-rainfall conditions. Baseline sampling was conducted when no rainfall event greater than 20 mm had occurred in the previous 1 to2 weeks, while post-rainfall sampling followed events exceeding 20 mm of precipitation within the prior 24 to48 h, consistent with NIWRA classification criteria. Elevated nutrient levels, especially total nitrogen (TN) and total phosphorus (TP) ,and episodic spikes during turbidity were frequently observed in impacted sites following storm-driven runoff (Donova, Proc Natl Acad Sci USA 10:5351–5357, 2020). Dissolved oxygen also fluctuated significantly in these areas, revealing episodic supersaturation (suggesting algal blooms) or localized oxygen depletion (Johnson, Sci Rep 11:23168, 2021). Reference sites, despite the fact that they are generally more stable, were not fully exempt from discrete surges of nitrogen or periodic turbidity increases. By examining both typical baselines and acute runoff episodes, NIWRA dataset shows how terresterial nutrient inputs, sediment-laden stormwater, and restricted circulation can lead to short-lived but highly stressful water quality conditions for corals. Consistent measurements across multiple laboratories—supported by interlaboratory comparisons (QA/QC)—establish a robust framework for site-specific guideline development. Findings indicate that nutrient over-enrichment poses a more pressing risk than heavy metals, highlighting the need for targeted watershed management, erosion control, and enhanced wastewater treatment to protect Norfolk Island’s reefs. Continued monitoring, paired with long-term trend analysis, is recommended to detect emerging issues, fine-tune guideline thresholds, and guide adaptive coastal management strategies to safeguard reef ecosystems under changing environmental pressures.