Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Project Information
• Funding

Abundance of Millepora species was examined by measuring percent cover at Cabritte Horn in St. John, US Virgin Islands across three decades.  Photographic sampling of quadrats (0.5m x 0.5 m) was performed from 1992 to 2021 using cameras mounted on a framer about 80 centimeters above the reef.  Color slide film was used from 1992–2000 (and digitized at 4000 dpi), with digital photography implemented in 2001.  Photoquadrats were recorded at random positions along the transect, which was 20 meters long from 1992–1999 and 40 meters long from 2000-2021.  

The abundance of Millepora sp. chaotically changed from 1992 to 2021 in concert with hurricanes, bleaching, and macroalgal crowding. To access images showing these patterns, see Related Publications section below for Coral Image Downloads and Viewer link (Cabritte Horn images can be found under "Random Sites").  For details on percent cover of macroalgae, see dataset https://www.bco-dmo.org/dataset/875543 (see Related Datasets section below). 

Photoquadrats were used to quantify Millepora abundance using ImageJ software (Abràmoff et al., 2004).  Areas of encrusting Millepora sp. were located in each photoquadrat, outlined, and their areas measured with all pieces of sheet forms quantified separately. Because Millepora species’ sheet forms meander across the substratum and are prone to fission, it was not always clear where colonies began and ended within photoquadrats. Colonies therefore were defined as areas of autonomous tissue, so portions of colonies that were partially within the photoquadrats (uncommon) were scored as separate colonies. The area of sheets were summed by quadrat and used to calculate the percentage cover of Millepora sp.

Statistical analyses
The morphology of Millepora sp. (log transformed), macroalgal cover (arcsine transformed), and temperature were compared among years using one way ANOVAs with Bonferonni post hoc analyses to compare between years (using Systat 13 software). The capacity of Millepora sp. to exploit a sheet-tree morphology was quantified (see 'Millepora features' dataset: https://www.bco-dmo.org/dataset/875553)

BCO-DMO processing
- converted Date to YMD format
- added columns for latitude and longitude
- added columns for location and camera type
- added conventional header with dataset name, PI name, version date
- modified parameter names to conform with BCO-DMO naming conventions

This project has been supported by continuing grants:
OCE-2019992 "RUI: Pattern and process in four decades of change on Caribbean reefs"  (2020-2026)
OCE-2546549 "RUI Pattern and process in five decades of change on Caribbean reefs" (2026-2029)

NSF award OCE-2546549 project summary:

Overview

This proposal focuses on American coral reefs in the United States Virgin Islands, most of which are trending towards persistent low coral colony abundances. This is a conspicuous aspect of the coral reef crisis, and while much is known of the disturbances causing corals to die, little is known about the ecological implications of low coral abundance. This project leverages four decades of research in St. John by using multiple sites to test five hypotheses addressing mechanisms preventing depleted coral populations from increasing in size, and they are developed in a hierarchical framework to advance basic ecology, and enhance understanding of coral reefs and the ecological processes structuring marine communities in the Anthropocene. The project is mensurative because it is conducted in an MPA, but its scope is broadened through: (a) analyses of algal symbionts (Symbiodiniaceae) with co PI, Cunning (Shedd Aquarium), (b) by extending the coral reef time-series from 40 to 43 yrs, and (c) applying wavelet analyses to the time-series. Three years of funding will support 1 mo/y of fieldwork, 11 mo/y of analysis, QA/QC, graduate training, a one year postdoc, outreach, and manuscript preparation. This RUI proposal is targeting the OCE call NSF PD 23-1650.

Intellectual merit

The intellectual merits lie in the hypotheses focused on the mechanisms leading to persistent low abundance coral communities. This project is designed around a conceptual model that preserves the integrity of a 43 yr time series and tests 5 integrated hypotheses addressing four science needs: (1) advancing basic ecology, (2) leveraging of existing data to realize emergent properties, (3) serving data to end users, and (4) outreach benefitting American stake holders. Over three years, fieldwork and analyses will address: H₁ Coral reef community structure is converging to a stable low coral abundance state; H₂. The impact of disturbances is mediated by the spatial structuring of community dynamics, and the expression of portfolio effects; H₃ Intensification of the coral recruitment ‘bottleneck’ and its gradual transition to settlement failure; H₄ Declining populations sizes of echinoids limit the formation of grazing halos in which corals settle; H₅ Persistence of low abundance coral communities is favored by changes in the symbiodiniacaea complement.

Broader impacts

This project will advance discoverability of time-series data in the public domain, student mentoring and experiential fieldwork, research on the causes of changes affecting marine communities, and in-person outreach at schools in California an Illinois, the University of the Virgin Islands, and the Friends of the VI National Park. Open access to high resolution data quantifying coral reefs over five decades is a critical community need to which this project will respond by placing in > 14,000 photoquadrats in the public domain (1987-present). Up to five graduate (MS) students will be mentored in marine science through fieldwork and lab analysis, and one REU students will be supported in a graduate mentoring framework. At middle schools, an “aquarium library” program will place marine animals in classrooms for 2–3 weeks in collaboration with the non-profit organization, ‘Underwater Zoo’. At high schools, ‘marine biology clubs’ will address project themes, provide research opportunities, and entrain teachers in field trips. In the field, teachers will conduct research leading to publications and will lead outreach activities with children in the junior ranger program administered by the Friends of the VI National Park. The efficacy of outreach tasks will be assessed through pre/post surveys and questionnaires administered using Google forms by teachers at partner schools. The results of assessment will be used to tune project deliverable to better meet the needs of the outreach audience.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Related Projects:

• Affiliated with MCR-LTER - https://www.bco-dmo.org/project/2222
• Serves as a new project that builds on NSF DEB-1350146 - RUI-LTREB Renewal: Three decades of coral reef community dynamics in St. John, USVI: 2014-2019 - https://www.bco-dmo.org/project/734983
• Overlaps with OCE 17-56678 (which focuses on soft corals with H. Lasker) - Collaborative Research: Pattern and process in the abundance and recruitment of Caribbean octocorals - https://www.bco-dmo.org/project/752508
• LTREB Long-term coral reef community dynamics in St. John, USVI: 1987-2019 - https://www.bco-dmo.org/project/2272
• RUI: Pattern and process in four decades of change on Caribbean reefs - https://www.bco-dmo.org/project/835192
• RAPID: Hurricane Irma: Effects of repeated severe storms on shallow Caribbean reefs and their changing ecological resilience - https://www.bco-dmo.org/project/722163