This dataset contains octocoral colony heights along with measures of damage and notes on the presence of epibionts found in 1m2 quadrats that were surveyed at 6 sites on the south shore of St. John, Virgin Islands, within the Virgin Islands National Park during July and August 2024 measured during transect surveys at four sites on the south shore of St. John, US Virgin Islands in 2024.

Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • BCO-DMO Processing Description
• Parameters
• Project Information
• Funding

Survey design:
All sites were located at 6 to 9 meters depth.

Censuses at East Cabritte, Europa, and Tektite were based on 50x10m areas that were arbitrarily selected and permanently marked with stainless steel eyebolts at the corners of the sites. A total of six transect lines, also marked with eyebolts, were laid out at 10 m intervals. All octocorals present in 1 x 1 m quadrats along the 10-meter long transects were scored. The transect identifier "transect_pos" has values 0, 10, 20, 30, 40 or 50 which represent position in meters within the 50x10 survey area corresponding to each of the 6 transects (e.g. 20 = 20m).

The census at Booby Rock was conducted using transects that were randomly placed along a 50 m line that was arbitrarily placed on a constant depth contour. The transect identifier (Transect_Position) for transects at Booby Rock refers to position along the 50 m line.

Yawzi and Deep Tektite surveys consist of 20 quadrats on each of 3 transects placed approximately 10 m apart. Yawzi transects were censused over two field trips, July/August and September.

Sampling methods:
Identifications were based on traits visible in the field, and samples of representative colonies were collected for further analysis in cases in which field identification was uncertain (Field_Species_Code). Sclerites from those samples were examined for species identification.

Two height measures are present: height of living tissue, which only includes that part of the axis with living tissue and total height which is the distance from the base to the tip of the farthest branch from the base (i.e. not necessarily perpendicular to the substrate), regardless of whether the tips or base had living tissue. (Only colonies with some living tissue were measured). All measures were rounded to the nearest cm with the exception of 5 cm which only includes colonies >= 5 cm. Starting in 2016, measures less than 5 cm reflect colonies with thick branches which could only have <5 cm heights due to partial mortality.

Revised species codes were used for colonies whose identification was subsequently changed or for species which were pooled with morphologically similar species that could not reliably be differentiated in the field.   See Parameters and supplemental file "species_codes.csv" for more information about Field_Species_Code and Revised_Species_Code.

Notes about identifications/codes: 

Octocoral adults are defined as individuals >= 5 cm height.  With height determined to the nearest cm

LINES WITH NO SPECIES ENTRY IDENTIFY QUADRATS IN WHICH NO OCTOCORALS WERE PRESENT-  This is also noted in the comment columns as "No colonies present."

Field identifications of Eunicea mammosa, E. laxispica and E. succinea  are sometimes difficult, thus, for analysis purposes, these species are lumped as a single group (Revised_Species_Code "ems").

Field identifications of  Pseudoplexaura flagellosa and P. wagenaari are difficult, thus, for analysis purposes these species are lumped as a single group (Revised_Species_Code "pfpw").

Field_Species_Code aa2 is an undescribed Antillogorgia sp. that is very similar to A. americana and is lumped with A. americana for analysis purposes.

Field identifications of Muricea muricata and M. atlantica are difficult. Thus, for analysis purposes, these species are lumped as a single group (Revised_Species_Code "mma").

Notes about Comments columns in this dataset:
  
Millepora present: Indicates millepora overgrowing naked axis
Cyanobacteria present: Indicates Cyanobacteria growing on the colony.
Spo or Sponge indicates sponge growing on the colony, most commonly on bare axis
"pale" or "bleached" indicates partial or complete bleaching of some branches on the colony
"ophio" or "Ophiothela" indicates the presence of Ophiothela mirabilis on the colony 
oyster indicates the presence of oyster(s) growing on the axis of the colony
"fallen" indicates the colony has fallen over but there is living tissue. Heights are based on the length of the living tissue on the substrate measured as if the colony were erect.
"Ophiothrix" indicates the presence of an "Ophiothrix sp." on the colony
"damselfish" indicates the colony was in a damselfish territory and some branches were being "farmed" by the damselfish

See "Parameters" section for more information about each column in this dataset.

* Sheet 1 "Adult_Surveys" of submitted file "2024_St John_adult_censuses for BCO-DMO.xlsx" was imported into the BCO-DMO data system as the main table for this dataset.  Table will appear as Data File: 956712_v1_st-john-octocoral-height-2024.csv (along with other download format options).

* Column names adjusted to conform to BCO-DMO naming conventions designed to support broad re-use by a variety of research tools and scripting languages. [Only numbers, letters, and underscores.  Can not start with a number]

* Date converted to ISO 8601 format

* Site name in the data table was revised from "Yawzi" to "Yawzi Point" as described in the provided site list and for consistency with other datasets. Latitude and Longitude joined into the octocoral height data table using this site list (joined on site name).

* World Register of Marine Species taxa match tool used (on 2025-03-21) to verify the correct spelling of species names were used and to match them to a Life Science Identifier (LSID). Not all matched the currently accepted name which may change over time. However all names were matched to identifiers for curation purposes. Incorrect spellings of species names were brought to the attention of the data submitter and were corrected in the octocoral height data:

The BCO-DMO data manager made two changes in the octocoral height data table 956712_v1_st-john-octocoral-height-2024.csv which was reviewed and confirmed by the data submitter.
Spelling of name: "Plexaura kukenthali"
corrected to: "Plexaura kuekenthali" (urn:lsid:marinespecies.org:taxname:290798) which is the currently accepted name of the junior synonym "Plexaura homomalla f. kuekenthali Moser, 1921" (see more at World Register of Marine Species (WoRMS) https://www.marinespecies.org/aphia.php?p=taxdetails&id=290798

Category: "Eunicea lacinata"
corrected to: "Eunicea laciniata" (urn:lsid:marinespecies.org:taxname:283250)

Since some species categories are pooled species groups, additional columns added for lowest taxon in the revised species code categories were added. The LSID for that taxon were added to the data table. LSIDs for the Genus column were also added.

Supplemental tables:

species_codes.csv
* The species code table was provided to BCO-DMO with name "HRL_revised--species_codes_table2.csv" (on 2025-09-26). It was renamed for clarity and brevity.
* Column names with spaces were replaced with underscores.
* Names were matched at the World Register of Marine species and the corresponding Life Science Identifier (LSID) were added (additional columns added: Lowest_taxon_for_category,Lowest_taxon_for_category_LSID).

site_list.csv
* This site list was provided to BCO-DMO on 2025-09-26.
* Longitude for Booby Rock changed from 64.7103 to -64.7103.

QA check:

All names presented in the BCO-DMO dataset are exact matches to names registered at the World Register of Marine Species (WoRMS). Some names are currently unaccepted synonyms (as of 2025-09-29). Accepted names change over time so please consult WoRMS and other authoritative sources which provides information for the name including current status and any synonyms.

Coverage: St. John, US Virgin Islands

NSF Award Abstract:
Coral reefs are exposed to a diversity of natural and anthropogenic disturbances, and the consequences for ecosystem degradation have been widely publicized. However, the reported changes have been biased towards fishes and stony corals, and for Caribbean reefs, the most notable example of this bias are octocorals ("soft corals"). Although they are abundant and dominate many Caribbean reefs, they are rarely included in studies due to the difficulty of both identifying them and in quantifying their abundances. In some places there is compelling evidence that soft corals have increased in abundance, even while stony corals have become less common. This suggests that soft corals are more resilient than stony corals to the wide diversity of disturbances that have been impacting coral corals. The best coral reefs on which to study these changes are those that have been studied for decades and can provide a decadal context to more recent events, and in this regard the reefs of St. John, US Virgin Islands are unique. Stony corals on the reefs have been studied since 1987, and the soft corals from 2014. This provides unrivalled platform to evaluate patterns of octocoral abundance and recruitment; identify the patterns of change that are occurring on these reefs, and identify the processes responsible for the resilience of octocoral populations. The project will extend soft coral monitoring from 4 years to 8 years, and within this framework will examine the roles of baby corals, and their response to seafloor roughness, seawater flow, and seaweed, in determining the success of soft corals. The work will also assess whether the destructive effects of Hurricanes Irma and Maria have modified the pattern of change. In concert with these efforts the project will be closely integrated with local high schools at which the investigators will host marine biology clubs and provide independent study opportunities for their students and teachers. Unique training opportunities will be provided to undergraduate and graduate students, as well as a postdoctoral researcher, all of whom will study and work in St. John, and the investigators will train coral reef researchers to identify the species of soft corals through a hands-on workshop to be conducted in the Florida Keys.

Understanding how changing environmental conditions will affect the community structure of major biomes is the ecological objective defining the 21st century. The holistic effects of these conditions on coral reefs will be studied on shallow reefs within the Virgin Islands National Park in St. John, US Virgin Islands, which is the site of one of the longest-running, long-term studies of coral reef community dynamics in the region. With NSF-LTREB support, the investigators have been studying long-term changes in stony coral communities in this location since 1987, and in 2014 NSF-OCE support was used to build an octocoral "overlay" to this decadal perspective. The present project extends from this unique history, which has been punctuated by the effects of Hurricanes Irma and Maria, to place octocoral synecology in a decadal context, and the investigators exploit a rich suite of legacy data to better understand the present and immediate future of Caribbean coral reefs. This four-year project will advance on two concurrent fronts: first, to extend time-series analyses of octocoral communities from four to eight years to characterize the pattern and pace of change in community structure, and second, to conduct a program of hypothesis-driven experiments focused on octocoral settlement that will uncover the mechanisms allowing octocorals to more effectively colonize substrata than scleractinian corals on present day reefs. Specifically, the investigators will conduct mensurative and manipulative experiments addressing four hypotheses focusing on the roles of: (1) habitat complexity in distinguishing between octocoral and scleractinian recruitment niches, (2) the recruitment niche in mediating post-settlement success, (3) competition in algal turf and macroalgae in determining the success of octocoral and scleractian recruits, and (4) role of octocoral canopies in modulating the flux of particles and larvae to the seafloor beneath. The results of this study will be integrated to evaluate the factors driving higher ecological resilience of octocorals versus scleractinians on present-day Caribbean reefs.

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.