Shallow Water Conductivity-Temperature-Depth (CTD) Profiles along a water quality gradient in Aua, American Samoa from 2022-09-13 to 2022-09-23

This metadata record describes the data collected from near-shore shallow water Conductivity-Temperature-Depth (CTD) casts conducted in Aua Reef, American Samoa, by scientists of the Ecosystem Sciences Division (ESD) of the NOAA Pacific Islands Fisheries Science Center (PIFSC) from September 13 - 23, 2022. For this fly-in mission (MP2206), the NOAA Fisheries, Ecosystem Sciences Division established 18 survey sites along the water quality gradient near land-based source pollution. This is part of a larger collection of datasets collected as part of the CRCP-funded project 'Linking watershed management activities to reef health in American Samoa' (Project #31303).

The CTD casts provide vertical profiles (5-m max depth, downcast only) of water column conductivity, temperature, and pressure (Sea-Bird Electronics, SBE19-plus), with calculated depth, salinity, and water density.

The CTD cast was conducted by snorkel. The CTD soaked at the surface for 1 minute to cycle water through the instrument and tubing. Afterward, data were collected by lowering the CTD in profiling mode at an even pace (descent rate ~0.5 to 0.75 meters per second) to a maximum depth of 5 m.

The focal point of this project was to establish a comprehensive biological, water quality, and carbonate chemistry baseline for Aua reef. This work aims at identifying measurable spatial differences in the structure and composition of the benthic and coral community at Aua that can be explained by measurable spatial patterns of water quality (nutrients and sediments) and water carbonate chemistry (pH and Alkalinity). This work is of fundamental importance for the development of the Aua Watershed Management Plan, and will enable Federal and jurisdictional resource managers to more effectively assess the effectiveness of watershed management actions reducing land-based pollution and impacts to the adjacent coral reef ecosystems.

This project builds on prior baseline and status and trends assessments conducted in 2012, 2015, and 2020 in Faga'alu Bay (U.S. Task Force watershed priority site) and Vatia (Territorial priority watershed) to address National and Jurisdictional goals to reduce land-based sources of pollution impacts in coral reef ecosystems.

This baseline assessment for land-based sources of pollution on Aua reef is part of a larger CRCP-funded project ID 31303: "Linking watershed management activities to reef health in American Samoa".

Water samples were collected alongside the CTD casts as part of this baseline assessment for the analysis of particulate and dissolved nutrients, total suspended solids, chlorophyll-a, and seawater pH and Alkalinity. Coral demographic, benthic cover, and non-coral community data was also collected as part of this project. These data are documented and archived separately.

CTD data include metadata for each observation and conductivity, temperature, and pressure observations with calculated depth, salinity and density.

While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

Extent of CTD data collected in Aua Reef via snorkeling during fly-in mission MP2206 (scientists flew into American Samoa conducted surveys)

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NOAA Coral Reef Ecosystem Sciences Division (ESD) Data Sharing Recommendations, version 9.0 updated August 12, 2015:

The ESD welcomes the opportunity to collaborate on research issues contributing to the scientific basis for better management of marine ecosystems. The ESD has a very diverse set of field activities that generates large volumes of data using an array of data collection protocols.

The following recommendations are for your consideration as you use this data:

1) Data analyses should take all field exigencies into account. The most effective way to do this would be active collaboration with ESD principal investigators.

2) In all presentations, product releases, or publications using data generated by ESD, proper acknowledgement of both ESD and the individuals responsible for data collection is expected. Citing the DOI (if available) is preferred, a non-DOI example is listed below.

3) If you collect or generate data for the same study areas, ESD requests that you share relevant information on complimentary data collections.

4) Those receiving data are strongly urged to inform the ESD Data Management Team of any errors and discrepancies that are discovered during the course of using these data. They are further urged to bring to the attention of the Team all problems and difficulties encountered in using these data. This information is necessary in order to improve the collections and to facilitate more efficient and economical data processing and retrieval. The users are asked to supply copies of any missing data that may be located, and to provide information as to significant subsets and special aggregations of data that are developed in using the material provided.

Example citation:

"This publication makes use of data products provided by the Coral Reef Ecosystem Sciences Division (ESD), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), with funding support from the NOAA Coral Reef Conservation Program (CRCP). The analysis and interpretations presented here are solely that of the current authors."

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

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Please cite PIFSC Ecosystem Sciences Division (ESD) when using the data.

Suggested Citation:

Ecosystem Sciences Division, Pacific Islands Fisheries Science Center, 2023: Shallow Water Conductivity-Temperature-Depth (CTD) Profiles along a water quality gradient in Aua, American Samoa from 2022-09-13 to 2022-09-23, https://www.fisheries.noaa.gov/inport/item/68094.

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Raw CTD profile data are downloaded from the RBR and saved as .CSV files.

SBE-19plus CTD sensor:

Conductivity - measurement range: 0-9 S/m; accuracy: +/- 0.0005 S/m; stability: 0.0003 S/m per month; resolution: 0.00005 S/m;

Temperature - measurement range: -5-35 deg C; accuracy: +/-0.005 deg C; stability: 0.0002 deg C per month; resolution: 0.0001 deg C;

Pressure - measurement range: 0-600 m; accuracy: +/- 0.1%; stability: +/- 0.1%; resolution: 0.002%

Obviously erroneous data have been removed from the final dataset. Missing values are indicated with a blank.

The same methods of data collection are used each time a CTD cast is conducted. Conductivity, temperature, pressure, depth, salinity, and density are routinely included in the observation dataset.

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

The data is captured in several locations: files stored on the PIFSC network. The PIFSC network is maintained and regularly backed up by PIFSC ITS.

Following a 1 minute soak, CTDs are usually deployed 5-10 feet above the reef at depths ranging from 0-5 m at 18 sites along the water quality gradient in Aua, American Samoa established by the NOAA Fisheries, Ecosystem Sciences Division.

Sites were selected randomly along a water quality gradient established by local knowledge.