These datasets represent the time to steady state photosynthesis (photosynthetic induction time) of Porites astreoides colonies classified as inside or outside of octocoral canopies. These data were used to test for the potential effect of light regimes created by octocoral canopies on the photophysiology of autotrophic taxa within the understories of octocoral forests. Additionally, these datasets contain information on the octocoral community surrounding each P. astreoides colony. Data was collected between July and August of 2019 at ~ 7.0 ± 0.5-m depth at three sites (White Point, Tektite, Cabritte Horn) in Lameshur Bay St. John, U.S. Virgin Islands. These data were collected as part of an NSF Coral Reef Time Series, Virgin Islands: Long-term coral reef community dynamics in the Virgin Islands National Park and were published in Girard and Edmunds (2023).

Table of Contents

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

Location:
Lameshur Bay St. John, U.S. Virgin Islands at ~ 7.0 ± 0.5-m depth
Research conducted from the University of the Virgin Islands Marine Station in Lameshure Bay during July – August 2019.

Methods & Sampling:

At each site (White Point, Tektite, Cabritte Horn) corals were haphazardly selected and categorized as within "dense" or "sparse" octocoral canopies. Colonies were categorized as within dense canopies if they were shaded by at least one octocoral colony ≥ 25 cm tall when it flexed in routine oscillatory water flow. Preliminary surveys showed that colonies of Porites astreoides (urn:lsid:marinespecies.org:taxname:288889) met this criterion when the distance from the nearest tall octocoral was less than half the height of the octocoral colony. The distance between P. astreoides colonies and the nearest octocoral was measured to categorize colonies of P. astreoides as within or outside the understory habitat. A single induction curve was performed on each P. astreoides on one of 16 days during July and August 2019. Sampled colonies were > 4 cm in diameter to provide space on the colony surface for the placement of the fiber-optic probe (5 mm diameter) attached to the Diving Pulse Amplitude-Modulation (PAM) fluorometer (Heinz Walz, GmbH) that was used to measure induction time. To standardize the light environment of samples all induction curves were performed between 09:00 and 11:00 hrs on clear cloudless days. In this study actinic light from the Diving PAM was set to 896 µmol photons m-2 s-1 during the induction protocol. There was a two-minute rest period between the first saturation pulse assessing Fm and the initiation of actinic light. Once turned-on, actinic light was continuously delivered for 17 minutes with a total of 13 saturating pulses being delivered one every 1.4 minutes.

Instruments:

PVC Quadrats (1 m2)
Transect tapes
Measuring ribbons with mm graduations
Underwater Fluorometer Diving-PAM (Heinz Walz GmbH)

To quantify induction time, the time to steady state photosynthesis was measured by evaluating the performance of photosystem II (PSII) using chlorophyll fluorescence (Bradbury and Baker, 1984, 1981). Calculation of the rate of production of high energy electrons by PSII (relative electron transfer rate, rETR) at a fixed Photon Flux Density is a measure of induction time (Suggett et al., 2010). rETR was calculated by the Diving PAM using the manufacturers software:

rETR = ΔF/Fm X PAR X 0.5 X 0.0001

where ΔF is the change in fluorescence (F) resulting from the saturation pulse, Fm is the maximum fluorescence, PAR is the PFD to which the sample is exposed, 0.5 is an estimate of the quanta absorbed by PSII, and 0.001 is an absorptance constant for light at the coral surface. As neither the absorptance of light by the coral surface, nor quanta by PSII, are known for P. astreoides, this equation estimates relative ETR.

To generate an induction time from Diving PAM rETR measurements the time to steady state photosynthesis (induction time) was taken as the intersection on the abscissa of two straight lines, one calculated using least squares linear regression of the first three points on the rETR curve, and the second representing the mean rETR of the last three points of the curve. This calculation was performed in Microsoft® Excel® for Microsoft 365 MSO (Version 2212 Build 16.0.15928.20196) by using the =Linest() function to generate a linear equation (y = mx + b) from the first three induction data points such that x is time (min) and y is rETR. Then solving for x (time) by using the mean of the last three rETR points as the rETR value (y).

 

BCO-DMO Data Manager Processing Notes:

* Source file "St.John_Porites Astreoides Induction Time and Octocorals.csv" imported into the BCO-DMO data system
* 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]
* lat and lon added to the data from a site list.
* Columns Mean_Octocoral_Height, Canopy_Closure_above_P_astreoides,Mean_rETR_3pts rounded to three decimal places.
* Date format converted to ISO 8601 format

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.

Website: http://coralreefs.csun.edu/

Coverage: United States Virgin Islands, St. John: 18.318, -64.7253

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