Nancy G. Prouty 20250717 comma-delimited text data release DOI: 10.5066/P1DVZPUV Pacific Coastal and Marine Science Center, Santa Cruz, California U.S. Geological Survey Suggested Citation: Prouty, N.G., 2025, Water and algal chemistry measurements collected from the National Park Service's National Park of American Samoa (NPS-NPSA) Ofu Island unit: U.S. Geological Survey data release, https://doi.org/10.5066/P1DVZPUV. https://doi.org/10.5066/P1DVZPUV Geochemical analysis of coastal springs and possible source waters were conducted in the National Park Service's National Park of American Samoa (NPS-NPSA) Ofu Island unit. Water samples were analyzed for dissolved nutrients, nitrate isotopes (delta-18-O and delta-15-N). Algae samples were collected and analyzed for delta-15-N and delta-13-C values. These samples were collected and analyzed as part of an effort to characterize the spatiotemporal variability of nutrient-enriched submarine groundwater (SGD) in NPSA. This project focused on identifying and quantifying the composition and fluxes of submarine groundwater discharged onto the reef. These results will inform help NPS-NPSA staff and local government to direct remediation actions related to outbreak of Valonia fastigiata algae. Additional information about the field activity or activities from which these data were derived is available online at: http://cmgds.marine.usgs.gov/fan_info.php?fan=2020-601-FA http://cmgds.marine.usgs.gov/fan_info.php?fan=2020-620-FA http://cmgds.marine.usgs.gov/fan_info.php?fan=2020-670-FA Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 20190705 20200209 Ground condition at time data were collected. Complete None planned -169.6767950 -169.6216050 -14.1850000 -14.1715070 ISO 19115 Topic Category oceans environment geoscientificInformation Data Categories for Marine Planning Water-Quality Parameters USGS Thesaurus geochemistry light stable isotope analysis chemical analysis Marine Realms Information Bank (MRIB) keywords coral reefs None U.S. Geological Survey USGS Coastal and Marine Hazards and Resources Program CMHRP Pacific Coastal and Marine Science Center PCMSC nutrients USGS Metadata Identifier USGS:67cf4de3d34ecfe34cc86a5b Geographic Names Information System (GNIS) Pacific Ocean Ofu Island Territory of American Samoa NGA GEOnet Names Server (GNS) Papaloloa Fattuana No access constraints USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey, and the National Park Service (NPS) as the originators of the dataset and in products derived from these data. U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

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Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Brendan Roark (Texas A&M) and Danielle Hull (University of Hawaii) completed the stable isotope analysis and nutrient analysis, respectively. Mac OS 11.4, Microsoft Excel 16.52 for Mac. D.M. Sigman K.L. Casciotti M. Andreani C. Barford M. Galanter J.K. Bohlke 2001 http://pubs.acs.org/doi/pdf/10.1021/ac010088e All geochemistry data were calibrated against known standards No formal logical accuracy tests were conducted. Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the metadata for each part of this data release carefully for additional details. Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the metadata for each part of this data release carefully for additional details. A formal accuracy assessment of the horizontal positional information in the data set has not been conducted. The horizontal accuracy is based on hand-held Garmin GPS. Horizontal accuracy is approximately 3 meters. A formal accuracy assessment of the vertical positional information in the data set has not been conducted. University of California, Davis Stable Isotope Facility 2020 seawater lab samples 20200913 Date when lab analyses were completed Nitrate delta-N-15 and delta-O-18 Denitrifier method of Sigman and others, (2001) using a Thermo Finnigan MAT 252 coupled with a GasBench II interface, isotope values are presented in per mil with respect to AIR for delta-N-15 and VSMO for delta-O-18 University of Hawaii, School of Ocean and Earth Science and Technology (SOEST) 2020 http://www.soest.hawaii.edu/S-LAB/slab_prices.htm water lab samples 20200408 Date when lab analyses were completed nutrient analysis Nutrient autoanalyzer for analysis for dissolved nutrient (nitrate, ammonia, phosphate, and silicate) concentrations. Texas A&M University 2020 http:// stableisotope.tamu.edu algae lab samples 20200723 Date when lab analyses were completed Stable isotope analysis Nitrogen (delta-N-15) and Carbon (delta-C-13) analysis on algae samples. Discrete water sampling included pumping from coastal springs at low tide and a groundwater well, marsh, and cesspool using a peristaltic pump with an in-line 0.45-micron filter and grab samples from the nearshore and reef flat by filtering with a 0.20-mircron syringe filter and storing frozen until analysis. Water samples were analyzed by several different labs (see Sources) for different variables. Data from all lab analyses were combined into a single document. -9999 cell value indicates no data (for example, where water sample was not analyzed for a particular variable given sample volume limitations). Algae samples were collected by snorkel, stored frozen, freeze dried at the lab, and homogenized prior to lab analysis for delta-N-15 and delta-C-13. nutrient analysis Nitrate delta-N-15 and delta-O-18 Stable isotope analysis 2020 lab data Water and algae data were combined into a single document (Ofu_water_algal_chemistry.csv). lab data 2020 Point Point 112 0.00000001 0.0000001 Decimal degrees D_WGS_1984 D_WGS_1984 6378137.000000 298.257224 Ofu_water_algal_chemistry.csv Output from chemical analysis of water and algae samples Producer defined. Sample ID Sample identification of sampled based on location (Ofu), site (CS=coastal spring, CP=cesspool, WL=well, MS=marsh, FR=forereef) or sample type (algae), sequential number and year of collection. Producer defined List of station names Date Sample collection date Producer defined. 2019-07-05 2020-02-09 YYYY-MM-DD Time Sample collection time (GMT-11). Values of -9999 indicate the parameter was not measured. Producer defined. 7:26 19:15 Hour:minutes Latitude Latitude of sample location Producer defined. -14.18533201 -14.17150700 decimal degrees 0.00000001 Longitude Longitude of sample location Producer defined. -169.6767950 -169.6216050 decimal degrees 0.000001 Salinity Measured salinity of water sample. Values of -9999 indicate the parameter was not measured. Producer defined. 0.1 35.0 parts per thousand 0.1 Temperature Measured temperature of water sample. Values of -9999 indicate the parameter was not measured. Producer defined. 25.5 29.4 degrees Celsius 0.1 Phosphate Dissolved inorganic phosphate concentration. Values of -9999 indicate the parameter was not measured. standard reporting value in inorganic chemistry 0.16 340.18 micromole per liter of seawater 0.01 Silicate Dissolved inorganic silicate concentration. Values of -9999 indicate the parameter was not measured standard reporting value in inorganic chemistry 0.91 1203.85 micromole per liter of seawater 0.01 Nitrate and nitrite Dissolved inorganic nitrate and nitrite concentration. Values of -9999 indicate the parameter was not measured standard reporting value in inorganic chemistry 0.37 52.83 micromole per liter of seawater 0.01 Ammonium Dissolved inorganic Ammonium concentration. Values of -9999 indicate the parameter was not measured. Values of -8888 indicate that the compound was not detected. standard reporting value in inorganic chemistry. 0.02 2783.34 micromole per liter of seawater 0.01 delta-N-15 delta-N-15 is a measure of the ratio of stable isotopes Nitrogen-15:Nitrogen-14, reported in parts per thousand (per mil). Values of -9999 indicate the parameter was not measured. standard reporting value in inorganic chemistry. -9.75 9.77 per mil 0.01 delta-O-18 delta-O-18 is a measure of the ratio of stable isotopes Oxygen-18:Oxygen-16 in water, reported in parts per thousand (per mil). Values of -9999 indicate the parameter was not measured. Producer defined. -1.79 4.84 per mil Percent organic nitrogen Percentage by weight (wt percent) of organic nitrogen; values of -9999 indicate the parameter was not measured. Producer defined 0.68 2.77 percent weight 0.01 delta-C-13 delta-C-13 is a measure of the ratio of stable isotopes Carbon-13:Carbon-12 in water, reported in parts per thousand (per mil). Values of -9999 indicate the parameter was not measured. Producer defined. -20.95 -5.18 per mil Percent organic carbon Percentage by weight (wt percent) of organic carbon; values of -9999 indicate the parameter was not measured. Producer defined 5.52 10.59 percent weight 0.01 The first line of the csv file is a header line. U.S. Geological Survey U.S. Geological Survey - ScienceBase mailing and physical

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Denver CO 80225 1-888-275-8747 sciencebase@usgs.gov These data are available in a comma-delimited text file (Ofu_water_algal_chemistry.csv) which contains water and algae analysis. Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. comma-separated text 16.52 comma-delimited text none 0.03702 https://www.sciencebase.gov/catalog/file/get/67cf4de3d34ecfe34cc86a5b https://doi.org/10.5066/P1DVZPUV Data can be downloaded using the Network_Resource_Name links. The first link is a direct link to download the zipped file of data and metadata. The second link points to the landing page for the entire data release. None. These data can be viewed with any text editor software. 20250717 U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

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Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998