gov.noaa.nodc:0306499 eng utf8 dataset NOAA National Centers for Environmental Information ncei.info@noaa.gov https://www.ncei.noaa.gov/contact HTTPS NOAA Contact Information Information for contacts at NCEI. information custodian 2026-06-08T13:22:20Z ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) Water quality surveys in Culebra: comprehensive assessment of inorganic nutrient concentrations 2023-05-03 to 2024-05-21 (NCEI Accession 0306499) 2025-07-30 publication 2025-11-04 revision 2025-07-23 creation International DOI Foundation (IDF) 10.25921/1e3k-9922 NOAA National Centers for Environmental Information gov.noaa.nodc:0306499 NCEI Archive Management System 0306499 NOAA National Centers for Environmental Information ncei.info@noaa.gov https://www.ncei.noaa.gov/contact HTTPS NCEI Contact Information Information for contacts at NCEI. information publisher Bernardo Vargas-Ángel NOAA Office for Coastal Management (OCM) bernardo.vargas-angel@noaa.gov https://coast.noaa.gov/ HTTPS NOAA Office for Coastal Management (OCM) website Institution web page information resourceProvider NOAA Office of Habitat Conservation (NMFS/OHC) https://www.fisheries.noaa.gov/about/office-habitat-conservation HTTPS NOAA Office of Habitat Conservation (NMFS/OHC) website Institution web page information resourceProvider Lisa Vandiver NOAA Restoration Center lisa.vandiver@noaa.gov https://www.fisheries.noaa.gov/about/office-habitat-conservation HTTPS NOAA Restoration Center website Institution web page information pointOfContact Viqueira-Rios, Jorge Protectores de Cuencas author Figueroa-Sanchez, Yasiel Protectores de Cuencas author Sanchez, Juan Protectores de Cuencas author Rivera-Rieira, Rebeca Protectores de Cuencas author Vargas-Ángel, Bernardo Lynker, under contract to NOAA Restoration Center bernardo.vargas-angel@noaa.gov author Vandiver, Lisa NOAA Restoration Center https://www.fisheries.noaa.gov/about/office-habitat-conservation HTTPS NOAA Restoration Center website Institution web page information author NOAA Office of Habitat Conservation (NMFS/OHC) https://www.fisheries.noaa.gov/about/office-habitat-conservation HTTPS NOAA Office of Habitat Conservation (NMFS/OHC) website Institution web page information contributor tableDigital This record describes water quality inorganic nutrient concentration metrics collected monthly between May 2023 to May 2024 to provide reference data of nearshore and watershed water quality on the island of Culebra, Puerto Rico. The water quality monitoring was conducted at 18 fixed stations. Five stations were selected to quantify Land Based Sources of Pollution (LBSP) stressor loads at key point and non-point sources in the Cabra, Coronel, and Aeropuerto watersheds. Levels of LBSP exposure were measured at 13 nearshore stations co-located with long-term seagrass monitoring sites. Nearshore monitoring sites were selected to identify watershed discharge points, coastal hydrodynamics, as well as the existing level of LBSP exposure and anticipated changes to LBSP exposure due to management actions. Nearshore monitoring stations were designated based on their land based sources of pollution management implementation status (LBSP Treatment Group), as follows: 1) LBSP Restoration stations: Located downstream where land-based pollutant management has or is being implemented. 2) LBSP Control stations: Represent a range of land-based pollutant impairments, including sites with no LBSP management, no known direct discharge of LBSP but are representative of the range of external factors that may be encountered at the LBSP Restoration stations. 3) Negative Reference stations of know significant -anecdotal and quantified- LBSP impairment. 4) Positive Reference stations of low LBSP impairment. Nearshore water quality samples were collected at two depths: surface (10-25 cm ) and bottom (2 m deep). Watershed water quality samples were collected only at surface. Water quality inorganic nutrient concentration metrics include: Nitrite, nitrate, ammonium, total nitrogen, orthophosphate, total phosphorus, and silica. The research questions, survey design and monitoring localities were specific to this study and the associated water quality data is unsuitable in a regulatory framework. The data presented herein was collected with financial support from NOAA Restoration Center and NOAA Coral Reef Conservation Program, and the National Fish and Wildlife Foundation (NFWF). These data address LBSP pollutant stressor and exposure monitoring, specifically inorganic nutrient concentrations, which together with LBSP habitat response monitoring represent the basis of Culebra's integrated LBSP Monitoring and Evaluation Framework with which to successfully assess progress and effectiveness toward achieving NOAA LBSP management goals and outcomes on Culebra. The parameters selected for monitoring are known to be good indicators of water quality condition (U.S. Coral Reef Taskforce Watershed Partnership Initiative Priority Ecosystem Indicators). In particular, indicators that are linked to both the LBSP management that is conducted in the watershed while also being linked to potential changes in habitat response. Within this context, water quality is characterized and tracked to quantify the land-based pollutant loads and exposure levels in the receiving coastal environment and the associated seagrass and coral reef communities, which are ultimately the focal point of NOAA's LBSP management efforts on Culebra. This data was collected with financial support from the NOAA Restoration Center, the NOAA Coral Reef Conservation Program, and the National Fish and Wildlife Foundation Funding Agency: NOAA Coral Reef Conservation Program Funding Agency: NOAA Restoration Center Funding Agency: National Fish and Wildlife Foundation completed historicalArchive NOAA National Centers for Environmental Information ncei.info@noaa.gov https://www.ncei.noaa.gov/contact HTTPS NCEI Contact Information Information for contacts at NCEI. information pointOfContact asNeeded NCEI Accession 0306499 was revised and a new version of the archival package was published. Updates to existing archival packages may provide additional files or replace obsolete files. The latest version contains the most complete and up-to-date representation of this archival information package. All of the files received prior to this update are available in the preceding version of this accession. Please see journal.txt in the /about directory for additional details on changes made. https://www.ncei.noaa.gov/access/metadata/landing-page/bin/gfx?id=gov.noaa.nodc:0306499 Preview graphic PNG 0306499 NCEI ACCESSION NUMBER 2025-10-29 publication AMMONIUM (NH4) NITRATE NITRITE NITROGEN phosphate silicate Total nitrogen TOTAL PHOSPHORUS theme NODC DATA TYPES THESAURUS laboratory analysis Niskin bottle nutrient autoanalyzer spectrophotometer instrument NODC INSTRUMENT TYPES THESAURUS in situ laboratory analyses manual sample collection physical theme NODC OBSERVATION TYPES THESAURUS NOAA Office of Habitat Conservation dataCentre NODC COLLECTING INSTITUTION NAMES THESAURUS NOAA Office of Habitat Conservation dataCentre NODC SUBMITTING INSTITUTION NAMES THESAURUS CORAL REEF STUDIES project NODC PROJECT NAMES THESAURUS Caribbean Sea place NODC SEA AREA NAMES THESAURUS oceanography theme WMO_CategoryCode 2012-09-15 publication DOC/NOAA/NMFS > National Marine Fisheries Service, NOAA, U.S. Department of Commerce dataCentre Global Change Master Directory (GCMD) Data Center Keywords 2026 revision 24 Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA) Greenbelt MD https://forum.earthdata.nasa.gov/app.php/tag/GCMD%2BKeywords HTTPS GCMD Keyword Forum Page Global Change Master Directory (GCMD). 2025. GCMD Keywords, Version 21. Greenbelt, MD: Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA). URL (GCMD Keyword Forum Page): https://forum.earthdata.nasa.gov/app.php/tag/GCMD+Keywords information custodian 30033 Reducing LBSP threats from unpaved roads on Culebra Island project CRCP Project Numeric Data Sets > Chemistry Numeric Data Sets > Water Quality theme CoRIS Discovery Thesaurus EARTH SCIENCE > Oceans > Ocean Chemistry > Nitrate EARTH SCIENCE > Oceans > Ocean Chemistry > Nitrite EARTH SCIENCE > Oceans > Ocean Chemistry > Nitrogen EARTH SCIENCE > Oceans > Ocean Chemistry > Nitrogen > Total EARTH SCIENCE > Oceans > Ocean Chemistry > Phosphate EARTH SCIENCE > Oceans > Ocean Chemistry > Phosphate > Total EARTH SCIENCE > Oceans > Ocean Chemistry > Phosphorus EARTH SCIENCE > Oceans > Ocean Chemistry > Silicate theme CoRIS Theme Thesaurus EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > AMMONIA EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > NITRATE EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > NITRITE EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > NITROGEN EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > PHOSPHATE EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > SILICATE theme Global Change Master Directory (GCMD) Science Keywords 2026 revision 24 Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA) Greenbelt MD https://forum.earthdata.nasa.gov/app.php/tag/GCMD%2BKeywords HTTPS GCMD Keyword Forum Page Global Change Master Directory (GCMD). 2025. GCMD Keywords, Version 21. Greenbelt, MD: Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA). URL (GCMD Keyword Forum Page): https://forum.earthdata.nasa.gov/app.php/tag/GCMD+Keywords information custodian Dissolved inorganic nutrient concentrations theme Provider Keywords AUTOANALYZER > AUTOANALYZER NISKIN BOTTLES OPTSPEC > Optical Spectrometer instrument Global Change Master Directory (GCMD) Instrument Keywords 2026 revision 24 Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA) Greenbelt MD https://forum.earthdata.nasa.gov/app.php/tag/GCMD%2BKeywords HTTPS GCMD Keyword Forum Page Global Change Master Directory (GCMD). 2025. GCMD Keywords, Version 21. Greenbelt, MD: Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA). URL (GCMD Keyword Forum Page): https://forum.earthdata.nasa.gov/app.php/tag/GCMD+Keywords information custodian COUNTRY/TERRITORY > United States of America > Puerto Rico > Culebra Island (18N065W0011) OCEAN BASIN > Atlantic Ocean > Caribbean Sea /North Atlantic Ocean > Puerto Rico > Culebra Island (18N065W0011) place CoRIS Place Thesaurus OCEAN > ATLANTIC OCEAN > NORTH ATLANTIC OCEAN > CARIBBEAN SEA place Global Change Master Directory (GCMD) Location Keywords 2026 revision 24 Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA) Greenbelt MD https://forum.earthdata.nasa.gov/app.php/tag/GCMD%2BKeywords HTTPS GCMD Keyword Forum Page Global Change Master Directory (GCMD). 2025. GCMD Keywords, Version 21. Greenbelt, MD: Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA). URL (GCMD Keyword Forum Page): https://forum.earthdata.nasa.gov/app.php/tag/GCMD+Keywords information custodian Culebra Island, Puerto Rico place Provider Place Names ERCP08 Send2NCEI Submission Package ID accessLevel: public otherRestrictions Cite as: Viqueira-Rios, Jorge; Figueroa-Sanchez, Yasiel; Sanchez, Juan; Rivera-Rieira, Rebeca; Vargas-Ángel, Bernardo; Vandiver, Lisa (2025). Water quality surveys in Culebra: comprehensive assessment of inorganic nutrient concentrations 2023-05-03 to 2024-05-21 (NCEI Accession 0306499). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/1e3k-9922. Accessed [date]. Distribution liability: NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives. otherRestrictions Use liability: NOAA and NCEI cannot provide any warranty as to the accuracy, reliability, or completeness of furnished data. Users assume responsibility to determine the usability of these data. The user is responsible for the results of any application of this data for other than its intended purpose. license This dataset has been dedicated to the public domain under the Creative Commons CC0 1.0 Universal (CC0 1.0) Public Domain Dedication. SPDX License: Creative Commons Zero v1.0 Universal (CC0-1.0) Vargas-Ángel, B. (2024). Culebra LBSP Ridge to Reef Monitoring Program. 2024-05-31 publication https://coast.noaa.gov/coral_storage/library/NOAA/CRCP/NMFS/OHC/Projects/30033/Culebra_LBSP_RidgeToReef_Monitoring_Program/Vargas-Angel2024_Culebra_LBSP_RidgeToReef_Monitoring_Program.pdf HTTPS https://coast.noaa.gov/coral_storage/library/NOAA/CRCP/NMFS/OHC/Projects/30033/Culebra_LBSP_RidgeToReef_Monitoring_Program/Vargas-Angel2024_Culebra_LBSP_RidgeToReef_Monitoring_Program.pdf Related report information Vargas-Ángel, Bernardo US DOC; NOAA; NOS; Office for Coastal Management author US DOC; NOAA; NOS; Coral Reef Conservation Program publisher documentDigital crossReference sciencePaper Vargas-Ángel, B. (2024). Culebra LBSP Ridge to Reef Monitoring Program Appendix A: Identifying Priority Fixed-Site Monitoring Locations. 2024-05-22 publication https://coast.noaa.gov/coral_storage/library/NOAA/CRCP/NMFS/OHC/Projects/30033/Culebra_LBSP_RidgeToReef_Monitoring_Program/Vargas-Angel2024f_Appendix-A_Identifying_Priority_Fixed-Site_Monitoring_Locations.pdf HTTPS https://coast.noaa.gov/coral_storage/library/NOAA/CRCP/NMFS/OHC/Projects/30033/Culebra_LBSP_RidgeToReef_Monitoring_Program/Vargas-Angel2024f_Appendix-A_Identifying_Priority_Fixed-Site_Monitoring_Locations.pdf Related report information Vargas-Ángel, Bernardo US DOC; NOAA; NOS; OFfice for Coastal Management author US DOC; NOAA; NOS; Coral Reef Conservation Program publisher documentDigital crossReference sciencePaper Vargas-Ángel, B. (2024). Culebra Nearshore Water Quality Monitoring Program Work Plan. 2024-05-22 publication https://coast.noaa.gov/coral_storage/library/NOAA/CRCP/NMFS/OHC/Projects/30033/Culebra_LBSP_RidgeToReef_Monitoring_Program/Vargas-Angel2024c_Nearshore_WaterQuality_Monitoring_WorkPlan.pdf HTTPS https://coast.noaa.gov/coral_storage/library/NOAA/CRCP/NMFS/OHC/Projects/30033/Culebra_LBSP_RidgeToReef_Monitoring_Program/Vargas-Angel2024c_Nearshore_WaterQuality_Monitoring_WorkPlan.pdf Related report information Vargas-Ángel, Bernardo US DOC; NOAA; NOS; OFfice for Coastal Management author US DOC; NOAA; NOS; Coral Reef Conservation Program publisher documentDigital crossReference sciencePaper Vargas-Ángel, B. (2024). Culebra Seagrass Monitoring Work Plan. 2024-05-22 publication https://coast.noaa.gov/coral_storage/library/NOAA/CRCP/NMFS/OHC/Projects/30033/Culebra_LBSP_RidgeToReef_Monitoring_Program/Vargas-Angel2024e_Seagrass_Monitoring_Transects_WorkPlan.pdf HTTPS https://coast.noaa.gov/coral_storage/library/NOAA/CRCP/NMFS/OHC/Projects/30033/Culebra_LBSP_RidgeToReef_Monitoring_Program/Vargas-Angel2024e_Seagrass_Monitoring_Transects_WorkPlan.pdf Related report information Vargas-Ángel, Bernardo US DOC; NOAA; NOS; OFfice for Coastal Management author US DOC; NOAA; NOS; Coral Reef Conservation Program publisher documentDigital crossReference sciencePaper Vargas-Ángel, B. (2024). Culebra Cabra Watershed Water Quality Monitoring Work Plan. 2024-05-22 publication https://coast.noaa.gov/coral_storage/library/NOAA/CRCP/NMFS/OHC/Projects/30033/Culebra_LBSP_RidgeToReef_Monitoring_Program/Vargas-Angel2024b_Watershed_WaterQuality_Monitoring_WorkPlan.pdf HTTPS https://coast.noaa.gov/coral_storage/library/NOAA/CRCP/NMFS/OHC/Projects/30033/Culebra_LBSP_RidgeToReef_Monitoring_Program/Vargas-Angel2024b_Watershed_WaterQuality_Monitoring_WorkPlan.pdf Related report information Vargas-Ángel, Bernardo US DOC; NOAA; NOS; OFfice for Coastal Management author US DOC; NOAA; NOS; Coral Reef Conservation Program publisher documentDigital crossReference sciencePaper U.S. Coral Reef Task Force (2016). USCRTF Watershed Partnership Initiative  Priority Ecosystem Indicators. 2016-02-18 publication https://taskforce.coralreef.noaa.gov/wp-content/uploads/2025/09/Priority_Ecosystem_Indicators_Final-2_18_16.pdf HTTPS https://taskforce.coralreef.noaa.gov/wp-content/uploads/2025/09/Priority_Ecosystem_Indicators_Final-2_18_16.pdf Related report information US Coral Reef Task Force - Watershed Working Group author U.S. Coral Reef Task Force publisher documentDigital crossReference sciencePaper eng; USA utf8 environment oceans -65.3083333 -65.2444444 18.288611 18.319444 2023-05-03 2024-05-21 In this accession, NCEI has archived multiple versions of these data. The latest (and best) version of these data has the largest version number. NOAA National Centers for Environmental Information +1-301-713-3277 ncei.info@noaa.gov pointOfContact In most cases, electronic downloads of the data are free. However, fees may apply for custom orders, data certifications, copies of analog materials, and data distribution on physical media. Contact NCEI for other distribution options and instructions. CSV PDF 9.148 https://doi.org/10.25921/1e3k-9922 HTTPS Web browser NCEI Dataset Landing Page Navigate directly to the URL for a descriptive web page with download links. information https://www.ncei.noaa.gov/archive/accession/oas/306499 HTTPS Web browser Descriptive Information Navigate directly to the URL for a descriptive web page with download links. information https://www.ncei.noaa.gov/archive/accession/download/306499 HTTPS Web browser HTTPS Navigate directly to the URL for data access and direct download. download ftp://ftp-oceans.ncei.noaa.gov/nodc/archive/arc0233/0306499/ FTP Any FTP client FTP These data are available through the File Transfer Protocol (FTP). FTP is no longer supported by most internet browsers. You may copy and paste the FTP link to the data into an FTP client (e.g., FileZilla or WinSCP). download dataset NCEI Accession 0306499 v1.1 was published. 2025-07-30T13:38:26Z NCEI Accession 0306499 v1.1 publication https://www.ncei.noaa.gov/archive/accession/0306499/1.1 HTTPS NCEI Accession 0306499 v1.1 published 2025-07-30T13:38:26Z download NCEI Accession 0306499 was revised and v2.2 was published. Updates were received for this dataset. These updates were copied into the data/0-data/ directory of this accession. These updates may provide additional files or replace obsolete files. This version contains the most complete and up-to-date representation of this archival information package. All of the files received prior to this update are available in the preceding version of this accession. 2025-11-04T19:19:44Z NCEI Accession 0306499 v2.2 publication https://www.ncei.noaa.gov/archive/accession/0306499/2.2 HTTPS NCEI Accession 0306499 v2.2 published 2025-11-04T19:19:44Z download dataset Parameter or Variable: Dissolved inorganic nutrient concentrations (measured); Units: mg/L; Observation Category: laboratory analysis; Sampling Instrument: laboratory analysis; Sampling and Analyzing Method: Discrete water samples (125 mL) were collected for the analysis of nutrients including nitrate, nitrite, orthophosphate, ammonium, total nitrogen, total phosphorus, and silica. Watershed samples were hand collected at surface (10-25 cm); nearshore samples were collected at the surface and bottom (~2 m deep; employing a Niskin bottle). Sterile nitrile gloves were worn at all times to avoid sample contamination. Samples were frozen and sent to the TDI-Brooks Laboratory for analyses. For further instrumentation and methodological details please review the Culebra Nearshore and Watershed Water Quality Monitoring Work Plans listed in the Summary Package under "References". Nitrate and nitrite analyses are based on the methodology of Armstrong et al. (1967) and utilize a ground Cd column for reduction of NO3- to NO2-. Orthophosphate is measured using chemistry based on the investigations of Bernhardt and Wilhelms (1967) with the modification of hydrazine as a reductant. Silicate determination is accomplished using the methods of Armstrong et al. (1967) using stannous chloride. Ammonium analysis is based on the method of Harwood (Harwood and Kuhn, 1970) using dichloro-isocyanurate as an oxidizer. Laboratory intercomparisons have been conducted and results are available. In order to increase processing efficiency and speed, voltage streams from the colorimeters are logged via a National Instruments acquisition board and data is acquired and stored using Labview. Peak processing is accomplished using software written in Matlab and software development continues. Peak voltage values associated with standards and samples can be determined with the written software, but manual checks and adjustment are still required at the present. The total concentrations of nitrogen and phosphorus are determined after an initial decomposition step. This method involves persulfate oxidation while heating the sample in an autoclave (115°C, 20 minutes)(Hansen and Koroleff 1999). After oxidation of the samples nutrient determination is conducted on the Technicon II analyzer. Samples are processed in batches of 30 with a full range of standards and blanks. All samples, standards, and blanks are run in a standard format as described above. Sample weight is recorded before and after oxidation treatment (and cooling) to detect any loss in volume. In order to determine total nitrogen and phosphorus a separate sample in addition to the volume taken for determination of dissolved components above must be provided. A 20 ml volume in the above-mentioned 30 ml Nalgene containers suffices. Currently five standards are run in duplicate at the beginning of each day. Line regression calculations are conducted to generate conversion equations. Correlation coefficients of 0.99 or better are achieved prior to analysis. At the end of each day's run all standards are analyzed again and regression analysis is conducted. The results of these regression analyses are compared to the initial determinations and adjustments can be made for instrument drift. Low-end standards are also analyzed along with an internal standard (Spex certified standard, Certiprep Inc.) between each batch of 10 samples with blank determination before and after each standard check. Blanks are also analyzed after each calibration in order to bracket each batch of 10 samples. These blanks are used to adjust the baseline and to monitor drift. Duplicate samples are analyzed with each batch. The %RPD must be less than 30% for each of the analytes measured if the detected analytes are detected at greater than 3x MDL. These methods are based on the following literature: Aminot, A. and R. Kerovel. 198. Dosage automatique de l'urée dans l'eau de mer: une méthode très sensible à la diacétylmonoxime. Can. J. Fish. Aquat. Sci. 39: 174–183. Armstrong, F. A. J., C. R. Stearns, et al. 1967. "The measurement of upwelling and subsequent biological processes by means of the Technicon Autoanalyzer and associated equipment." Deep-Sea Research 14(3):381–389. Bernhardt, H. and A. Wilhelms (1967). The continuous determination of low level iron, soluble phosphate and total phosphate with the AutoAnalyzer. Technicon Symposium. Hansen, H. P. and F. Koroleff (1999). Determination of Nutrients. Methods of Seawater Analysis. In: K. Grasshoff, K. Kremling and M. Ernhardt. New York, Wiley-VCH:159–251. Harwood, J. E. and A. L. Kuhn (1970). "A colorimetric method for ammonia in natural waters." Water Research 4:805–811.; Data Quality Method: The quality control occurred at several stages major stages: 1) instrument calibration; 2) sample collection; 3) data entry, and 4) data management. Data entry quality control included both review and manual error correction steps including purging data outside the instruments' parameter detection ranges. Water quality measurements were made implementing state-of-the-art instrumentation. Handheld GPS units were used to locate sites and mark site locations. Survey methods were consistent across dates and sites. Data gaps may originate from, but not limited to, instrument malfunction, weather conditions, and the data quality control process. asNeeded Metadata are developed, maintained and distributed by NCEI. Updates are performed as needed to maintain currentness. NOAA National Centers for Environmental Information custodian laboratory analysis laboratory analysis use as an observation type Niskin bottle Niskin bottle Device for obtaining samples of seawater at a specific depth Why special entry for Niskin bottle but no entry for Nansen bottle? nutrient autoanalyzer nutrient autoanalyzer Laboratory Instrument Nutrient Autoanalyzer is a generic term describing an automated flow-thru system used to conduct analyses of several different nutrients (nitrate, ammonium, orthophosphate, and silicate) simultaneously from a seawater sample. For example: SEAL AutoAnalyzer 3 HR Continuous Segmented Flow Analyzer spectrophotometer spectrophotometer spectrophotometer, optical spectrometer, spectrograph or spectroscope An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. Butler, L. R. P.; Laqua, K. (1995). "Nomenclature, symbols, units and their usage in spectrochemical analysis-IX. Instrumentation for the spectral dispersion and isolation of optical radiation (IUPAC Recommendations 1995)". Pure Appl. Chem. IUPAC. 67 (10): 1725–1744. doi:10.1351/pac199567101725. A spectrometer is the general term for describing a combination of spectral apparatus with one or more detectors to measure the intensity of one or more spectral bands."