Experimental coral-growth data and time-series imagery for Acropora palmata and Pseudodiploria strigosa in St. Croix, U.S. Virgin Islands

Acropora palmata growth: Acropora palmata coral fragments were obtained from five colonies at Buck Island Reef National Monument chosen based upon historical knowledge of their condition over time, referred to as “legacy colonies”, as expressed by Zandy Hillis-Starr of the National Park Service (NPS). On June 24, 2019, USGS and NPS personnel collected 6 small branch tips each from these five distinctive, large colonies of A. palmata. A pneumatically powered, reciprocating saw attached to a Self-Contained Underwater Breathing Apparatus (SCUBA) tank was used to cleanly cut the branch tips from the colonies, and then the corals were mounted on plastic (polyvinyl chloride) PVC disks with epoxy and fitted with stainless-steel bolts as described in Morrison and others (2013). Pseudodiploria strigosa growth: On June 26 and 27, 2019, ten small Pseudodiploria strigosa colonies each were collected from the south forereef (SFR) and northeast reef (NER) at Buck Island Reef National Monument, respectively, and mounted to plastic discs as described above. Because of inclement weather, P. strigosa deployed to the northwest reef (NWR) site were not collected until November 2019, and because there were no colonies found at that site, colonies deployed there were collected from the SFR site. The 30 P. strigosa colonies were stained with alizarin-red on the day they were deployed for later sectioning and use for measurement of linear extension and development and calibration of the Strontium/Calcium (Sr/Ca) temperature proxy. The 60 prepared coral colonies were deployed to the field sites to grow for a total of two years at the south forereef (SFR), northeast reef (NER), and northwest reef (NWR) sites. The corals were reversibly attached with a washer and wingnut to concrete blocks secured to the substratum. At the start of the experiment and during the four subsequent sampling visits, all corals were photographed, measured with calipers (length x width x height), and weighed using the buoyant-weight method (Jokiel and others, 1978). For more details about the methods used, refer to Morrison and others (2013). For the final sampling, because the caliper measurements performed by volunteers in July 2021 showed an unlikely average loss of coral planar area and height signifying insufficient training, USGS personnel remeasured the colonies in August 2021 and report these measurements in lieu of those made in July. Corals that died during the experiment were not included in further assessments of growth metrics (missing data are left blank). Calcification rates were normalized to the planar-footprint area of the colony at the beginning of each weighing interval as determined using calipers and the formula for the area of an ellipse.

Photography: The photographs of the corals were taken by USGS personnel (E. Lyons and A. Stathakopoulos) or by NPS personnel (K. Ewen and Nathaniel Hanna Holloway) using a Nikon COOLPIX camera mounted on a tripod. The digital photographs were taken in the field of each colony with a ruler for scale. The images were subsequently used to create a time-series montage for each coral (L. Bartlett). Images were color corrected as needed and stitched together in chronological order using Adobe Photoshop CC version 23.3.2 to adjust for light regime and enhance contrast and brightness. Additionally, text indicating the coral identification number (if not handwritten on the photo stand with red-waxed pencil), the sampling season, and year were added to each image using Photoshop. The digital images are included in the data release download file, VI_coral_photo_record.zip.

Populating the image headers: Credit, contact information, copyright, usage terms, image descriptions, attribution url, metadata link, and georeferencing information were added to the exchangeable image file format (EXIF) header of each image using Phil Harvey’s ExifTool (version 12.44). Each coral species (APAL for Acropora palmata and PSTR for Pseudodiploria strigosa) and sample site (SFR, NER, NWR) were grouped together and the command was run on each group of images. The image groupings were as follows: APAL SFR, PSTR SFR, APAL NER, PSTR NER, APAL NWR, and PSTR NWR. All information in the script were the same among all images, aside from the EXIF:ImageDescription, EXIF:GPSLatitude and EXIF:GPSLongtitude information, as that information varied between the grouped site and coral species images. First, the following command was run on the grouped images to preserve filenames: exiftool -P "-XMP:PreservedFileName<Filename" *.JPG. Second, the following command was run on the grouped images to populate the image headers. This example command was run on the APAL SFR images: exiftool -IPTC:Credit="U.S. Geological Survey" -IPTC:Contact="[email protected]" -EXIF:Copyright="Public Domain" -XMP:UsageTerms="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 for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty." -EXIF:ImageDescription="Time-series photographs taken of colonies of the elkhorn coral, Acropora palmata, grown at south forereef at Buck Island Reef National Monument from June 2019 to July 2021." -XMP:AttributionURL="https://doi.org/10.5066/P94BOI9T" -EXIF:GPSAreaInformation="Location of collection site, GPS coordinates are approximate" -XMP:ExternalMetadataLink="https://data.usgs.gov/datacatalog/metadata/USGS.d5b888e0-7781-44a0-8802-48c240a5cc00.xml" -EXIF:GPSLatitude="17.78408" -EXIF:GPSLatitudeRef="N" -EXIF:GPSLongitude="64.61416" -EXIF:GPSLongitudeRef="W" *.JPG To extract the information from the image headers using ExifTool, run the following command after connecting to the unzipped folder containing the images (VI_coral_photo_record): exiftool a.jpg, where 'a' is replaced with the filename. Example: exiftool APAL_NER_113_SideView.jpg