Catchment to sea connection: Impacts of terrestrial run-off on benthic ecosystems in American Samoa

• Published in: Marine pollution bulletin Vol. 169; p. 112530
• Main Authors: Comeros-Raynal, Mia T., Brodie, Jon, Bainbridge, Zoe, Choat, John Howard, Curtis, Meagan, Lewis, Stephen, Stevens, Thomas, Shuler, Christopher K., Sudek, Mareike, Hoey, Andrew S.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-08-2021; Elsevier BV
• Subjects: Anthropogenic factors; Benthos; Catchment area; Community structure; Composition; Coral reefs; High islands; Human influences; Islands; Land use; Mineral nutrients; Nutrient concentrations; Nutrients; Oceanic islands; Particulate matter; Phosphates; Ridge-to-reef; Runoff; Sedimentation; Suspended particulate matter; Temporal variations; Terrestrial environments; Water quality; Watersheds; United States > US; American Samoa; Coral reefs; Suspended particulate matter; Water quality; Nutrients; Ridge-to-reef; Sedimentation; Land use; High islands
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2021.112530

Variation in water quality can directly affect the composition of benthic assemblages on coral reefs. Yet, few studies have directly quantified nutrient and suspended particulate matter (SPM) to examine their potential impacts on benthic community structure, especially around high oceanic islands. We assessed the spatio-temporal variation of nutrients and SPM across six sites in American Samoa over a 12-month period and used exploratory path analysis to relate dissolved inorganic nutrients, land use, and natural and anthropogenic drivers to benthic assemblages on adjacent shallow reefs. Multivariate analyses showed clear gradients in nutrient concentrations, sediment accumulation and composition, and benthic structure across watersheds. Instream nutrients and land uses positively influenced reef flat nutrient concentrations, while benthic assemblages were best predicted by wave exposure, runoff, stream phosphate and dissolved inorganic nitrogen loads. Identifying locality-specific drivers of water quality and benthic condition can support targeted management in American Samoa and in other high islands.