Jurisdictional managers have expressed concerns that nutrients from the village of Vatia are having an adverse effect on the coral reef ecosystem in the bay. Excess nutrient loads promote increases in algal growth which can have deleterious effects on corals, such as benthic algae outcompeting and overgrowing corals. Nitrogen and phosphorus can impact corals directly by lowering fertilization success, and reducing both photosynthesis and calcification rates. Land-based contributions of nutrients come from a variety of sources; in Vatia the most likely sources are piggeries and septic systems. This project will continue to quantify the nutrient dynamics of the bay and concurrently measure benthic algal proliferation/blooms in order to assess the link between nutrient pollution and coral reef ecosystem health. This will be accomplished with monthly water quality sampling (nitrate/nitrite, ammonium, urea, total nitrogen, orthophosphorus, and total phosphorus). This water quality sampling began in 2015. Additionally, the PIs will explore the possibilities of using additional analytes unique to human waste (e.g. caffeine) to help discriminate between human and animal sources. In 2015, spatially explicit, benthic surveys were undertaken in the Bay to establish a comprehensive baseline for benthic composition and coral demographics. In 2016, replicate long-term monitoring stations will also be deployed (using photo quadrats) to assess changes both in the coral and algal communities.. These efforts feed into the higher-level Programmatic Objectives by establishing an in-situ tracking system to assess the effects of management and mitigation strategies/activities in the target watersheds to reduced land-based sources of pollution. Project partners will include NMFS-CRED, AS Coral Reef Advisory Group, the American Samoa Environmental Protection Agency, American Samoa Department of Marine and Wildlife Resources, and American Samoa Community College. To the extent possible, this project will leverage other planned/proposed NOAA field efforts.
This project will provide a quantitative assessment of the potential link between nutrient chemistry and reef health. This will serve multiple management purposes. First, it will provide information that managers can use to determine the cause of benthic algal blooms. Second, it will provide a baseline of nutrient concentration in Vatia which will be useful to managers in tracking change over time, including assessing the efficacy of management actions. Finally, source specific pollutants (e.g. caffeine) in combination with watershed nutrient budget calculations may shed light on the relative importance of septic systems versus piggeries as sources of nutrients to Vatia Bay. The project has already accomplished a significant technology transfer by training 20 local scientific staff to conduct nutrient sampling.
Jursdiction Priority Sites:
Land-based Sources of Pollution (LBSP)