Data Management Plan

The ocean acidification diel suite is an autonomous instrument package that measures diel variability in coral reef seawater carbonate chemistry. Diel suite surveys are conducted by the NOAA Pacific Islands Fisheries Science Center (PIFSC), Ecosystem Sciences Division (ESD) within coral reef ecosystems across the Pacific Islands Region as part of the NOAA National Coral Reef Monitoring Program (NCRMP). The data provided in this data set are from diel suites deployed at select sites at Tutuila Island in March 2015 and June - July 2018, during the ESD-led NCRMP missions to American Samoa.

Diel suites were deployed on the reef for at least 24 hours to measure in-situ salinity, temperature, pressure, pH, current direction and magnitude, and dissolved oxygen (starting 2018). Seawater samples were also collected for laboratory analyses of dissolved inorganic carbon (DIC) and total alkalinity (TA). Components of the carbonate system--including pH, pCO2 (partial pressure of carbon dioxide), and aragonite saturation state--are calculated from DIC, TA, temperature, salinity and pressure. Each diel suite typically consisted of: 1 SBE-19plus CTD sensor, 1 Nortek Acoustic Doppler Current Profiler (ADCP), 1 Satlantic SeaFET Ocean pH sensor, and up to 9 Programmable Underwater Collectors (PUCs), each of which collected 1 water sample at 3- or 4-hour intervals. Starting 2018, 1 SBE-43 oxygen sensor is tethered to the CTD sensor for diel surveys. Diel surveys from 2019 also incorporate stand-alone PAR and DO loggers however they have yet to be conducted in American Samoa. Instruments deployed, samples collected, and sample intervals are recorded in the summary file enclosed with the data package, and exceptions to the standard diel suite are also noted.

Extent of diel survey sites at Tutuila, American Samoa during the ASRAMP cruise (HA1501) in 2015. Associated REA Sites: TUT-73 and TUT-75.

Extent of diel survey sites at Tutuila, American Samoa during the ASRAMP cruise (HA1801) in 2018. REA Site TUT-74

Lineage Statement:
The ocean acidification diel suite is a collection of instruments deployed by SCUBA divers onto the seafloor that makes autonomous measurements and collects seawater samples. For a typical deployment, the diel suite consists of: 1 Sea Bird Electronics (SBE)-19plus CTD, 1 Nortek Acoustic Doppler Current Profiler (ADCP), 1 Satlantic SeaFET Ocean pH sensor, and up to 9 Programmable Underwater Collectors (PUCs), where each PUC collects 1 water sample at a 3- or 4-hour interval over a minimum 24-hour period. All instruments are weighted or zip-tied to rubble on the seafloor, or both, to secure the position of the instrumentation for the duration of the deployment. An oxygen sensor was included in the diel suite deployment from 2018.

Process Steps:

• Water samples collected with Programmable Underwater Collectors (PUC) Developed by Dr. Chris Langdon's laboratory at the University of Miami, PUCs are computerized timers attached to a low-power peristaltic pump. An array of PUCs collects water samples at 3- or 4-hour intervals over the course of at least 24-hours, usually starting at 12:00 pm local time on day 1 and ending at 12:00 pm on day 2. While PUCs are programmed to collect water on this regular sampling schedule, issues with the pumps can occasionally result in missing samples for some of the time steps. For some deployments, paired water samples were collected simultaneously at the benthos and 1.5 meters above the seafloor. Samples are collected underwater in tedlar bags pre-poisoned with mercuric chloride and transferred to glass bottles within a few hours of recovery. Water samples are analyzed for DIC using a coulometer (SOP #2) and for TA using a titrator (SPO #3b) by the NOAA Pacific Marine Environmental Laboratory. On occasion, poor pump performance results in half-filled sample bags. These samples are only analyzed for TA due to insufficient sample volume for DIC analysis. Full carbon system chemistry values (including pH, pCO2, and aragonite saturation state) are derived from DIC/TA and salinity/temperature/pressure data from a co-deployed CTD using the R package seacarb. Discrete sample pH data are compared to SeaFET pH data. (Citation: Dickson, A.G., Sabine, C.L. and Christian, J.R. (Eds.) 2007. Guide to best practices for ocean CO2 measurements. PICES Special Publication 3, 191 pp.)
• Acoustic Doppler Current Profiler (ADCP) sensor The diel suite includes either a 1.0 MHz or a 2.0 MHz side-looking ADCP (1.0 MHz ranges 20-m depth, while the 2.0 MHz ranges 10-m). ADCP measurements are collected at 2 minute intervals and binned by height above the sensor. Each height bin is represented in the data set as the upper limit of the bin height above the sensor on the seafloor (e.g., a 1.4 m bin represents current data collected between 0.4 m and 1.4 m above the ADCP). ADCP data include a blanking region, or a small distance in front of the transducer in which measurements cannot be made, of 0.2-0.4 m. Current data are grouped into 1-m height bins. Raw data downloaded from the ADCP are processed in R using the oce package. XYZ coordinate data are converted to ENU (east-north-up) coordinate system. Current speed is calculated as the square root of the sum of the squared u and v velocities and direction as the arctan(v/u). Data are trimmed to a maximum height bin for each time step using pressure data to remove above-water signal. As a result, NULL values may exist for larger height bins above the surface of the water due to waves and tides.
• Conductivity-Temperature-Depth (CTD) sensor CTD data are collected by a Sea Bird Electronics 19plus v2 SeaCAT every 5 minutes. Data are uploaded as HEX files, converted to CNV using SBE Data Processing Software, and converted to CSV using the 'oce' package in R.
• SeaFET pH sensor The SeaFET pH measures in-situ pH using a solid state ISFET sensor with an AgCl external reference electrode. The electrode is conditioned in running seawater up to a week prior to deployment and stored in artificial seawater between deployments. pH data are collected in bursts of 30 measurements every 5 minutes. The SeaFET is co-deployed with a CTD, and temperature and salinity values from the CTD time series are used to correct the raw pH time series. The SeaFET derives pH from both internal and external potentiometric cells, but only external pH is reported. SeaFET pH values are compared to pH values calculated from discrete TA and DIC samples collected at the same time and location.
• Oxygen sensor An SBE-43 oxygen sensor is tethered to the SBE-19plus CTD sensor to provide DO readings in mg/L of diel suite deployment.

The data is quality controlled by NOAA PIFSC Ecosystem Sciences Division (ESD) personnel after the data is downloaded from the instruments, after it is migrated to the database, and once again when the data are submitted to the NOAA National Centers for Environmental Information.

NOAA Pacific Marine Environmental Laboratory (PMEL) conducts quality assurance and quality control on their seawater analyses according to protocols #2 and #3b in Dickson et al (2007).

Data can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive.

The data is captured in several locations: files stored on the cruise server during the mission and the PIFSC network, and data are imported into the PIFSC Oracle database. The cruise server is regularly backed up by the cruise data manager while at sea, and the PIFSC network and Oracle database are maintained and regularly backed up by PIFSC ITS.