Transect surveys were conducted at 6 sites on the south shore of St John, within the U.S. Virgin Islands National Park during the summers of 2021 and 2022. Depending on the site, 3 to 6 transects were established. Identity and heights of all arborescent octocorals greater than or equal to 5 centimeters were recorded from 1 square meter quadrats on the transects. The position of colonies relative to the site, meter on the transect, and side of the quadrat are included. Surveys were conducted by Drs. Howard Lasker and Christopher Wells of the University at Buffalo.

Table of Contents

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

To investigate community dynamics of octocorals on Caribbean coral reefs, transect surveys were conducted at 6 sites on the south shore of St John, within the Virgin Islands National Park during the summers of 2021 and 2022.  Depending on the site, 3 to 6 transects were established. All sites were located at 6 to 9 meters depth and samples were collected by SCUBA from small boats. The identity and heights of all arborescent octocorals greater than or equal to 5 centimeters were recorded from 1 square meter quadrats on the transects.  The position of colonies relative to the site, meter on the transect, and side of the quadrat are included.

Censuses at sites Grootpan, Europa, and Tektite were based on 50-meter x 10-meter 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. At Booby Rock, a 50-meter line running parallel to the approximately 7-meter depth contour was established, and survey transects (3 in 2021 and 6 in 2022) were positioned at random points along the line.  All octocorals present in 1 x 1-meter quadrats along the 10-meter long transects were identified and their heights were measured. Small branch tip samples were collected from colonies that could not be identified in the field.  Sclerites were digested from those colonies with a commercial bleach solution and sclerites were observed with a compound scope for identification. Octocoral adults were defined as individuals greater than or equal to 5 centimeters in height, with height determined to the nearest centimeter.

Known Issues:
Field identifications of Pseudoplexaura flagellosa and P. wagenaari  are difficult among small colonies and for analysis purposes, the two species should be lumped as a single group.

Field identifications of Eunicea mammosa, E. laxispica and E. succinea  are sometimes difficult, thus, for analysis purposes the three species should be lumped as a single group.

aa2 is an undescribed Antillogorgia sp. that is very similar to A. americana.

 

Data were collected on paper and slates and transcribed to Excel files each day of fieldwork.

BCO-DMO Processing description:
- Adjusted field/parameter names to comply with BCO-DMO naming conventions
- Added columns "Latitude" and "Longitude" based on site
- Rounded columns "Latitude" and "Longitude" to 3 decimal places

 

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.