Home > Explore Data & Reports > Excess Nutrients in Vatia Bay, American Samoa: Spatiotemporal Variability, Source Identification and Impact on Coral Reef Ecosystems


Whitall, D., M. Curtis, A. Mason, and B. Vargas-Angel. 2019. Excess Nutrients in Vatia Bay, American Samoa: Spatiotemporal Variability, Source Identification and Impact on Coral Reef Ecosystems. NOAA Technical Memorandum NOS NCCOS 266. Silver Spring, MD. 69 pp. doi:10.25923/j8cp-x570

Data/Report Type:

NOAA Technical Memorandum


Water quality problems, including sedimentation and over enrichment of nutrients, have the potential to adversely impact coral reef ecosystems. Phosphorus and reactive nitrogen can enter the environment from chemical fertilizers (residential, commercial and agricultural uses), industrial sources, animal waste, and human waste. Excess nutrient loads can impact coral both directly (e.g. lowered fertilization rates) and indirectly (macroalgal overgrowth). The benthic habitat of Vatia Bay (American Samoa) is a mixture of hard bottom (live coral, coral rubble, pavement), crustose coralline algae (CCA), fleshy macroalgae, and turf algae, with small patches of sand. There have been local concerns about the impacts of land based sources of pollution and water quality on the coral reef ecosystems of Vatia Bay (NOAA CRCP). Household sewage from the village is treated via septic systems, cesspits, or in some cases, may go untreated. There are small agricultural operations (bananas, taros, vegetables, piggeries in the village), but no industry or other businesses in the watershed. Feral dogs may also be contributing to the nutrient budget of the Bay. The goals this study were to: quantify the magnitude and spatiotemporal variability of surface water nutrients in the Bay; establish a baseline of nutrient conditions against which to measure changes in the future; link observed concentrations of nutrients to hydrologic forcing factors and possible nutrient sources; use human dietary chemical indicators to evaluate if human waste is reaching Vatia Bay; and correlate observed patterns in nutrient dynamics with measured indices of coral ecosystem health.

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