TITLE:
Variability of Carbon Chemistry at the Marine Protected Area of Savaia Village, Upolu Island, Samoa
AUTHORS:
Patila Amosa, Asonei Leauga, Varea Vaurasi, Faainuseiamalie Latu, Toetu Leasi, Sekotilani Aloi Gray, Jeffery Leung Wai, Aleluia Taise Uili
KEYWORDS:
Ocean Acidification, Total Alkalinity, pH, Samoa, Dissolved Carbon Dioxide
JOURNAL NAME:
Open Journal of Marine Science,
Vol.16 No.3,
July
30,
2026
ABSTRACT: The Pacific Small Island Developing States (Pacific SIDS) are at the forefront of climate change impacts, yet these effects remain understudied and therefore poorly understood. Ocean acidification (OA) research in Samoa is in its infancy, with a new OA project established to monitor seawater carbon chemistry in coastal ecosystems. The study measured seawater carbon chemistry—including pH, dissolved carbon dioxide and total alkalinity—within the marine protected area (MPA) of Savaia, Lefaga, on Upolu Island, Samoa. Sampling was conducted over twelve months at four locations within the MPA (Site 1, Site 2, Site 3, Site 4), focusing on spatio-temporal variability in pH, temperature and total alkalinity. Measurements were obtained using water samples and an iSAMI pH sensor. The mean pH recorded was 8.06 ± 0.07, while the mean total alkalinity was 1955.1 ± 25 µmol∙kg−1, which is lower than the typical value of 2305 µmol∙kg−1 observed in tropical environments. This decline in total alkalinity and the corresponding low pH could be a potential source of acidification to downstream coastal ecosystems with potential implications for coral reefs, biodiversity and fishery livelihoods.