Table of Contents

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

Coral cores of 2.5-centimeter (cm) diameter were collected from tagged colonies of three coral species in either April 2019 or October 2019 from Emerald Reef in Southeast Florida, USA. Cores were then maintained in 300-liter (L) indoor flow-through aquaria (in the Marine Technology and Life Science Seawater complex at the University of Miami's Rosenstiel School of Marine, Atmospheric, and Earth Science) and subjected to experimental heat stress. Before, during, and following the heat stress, 2-millimeter (mm) tissue samples were collected from cores and genomic DNA was subsequently extracted from these samples as per Cunning & Baker (2016). Quantitative PCR was performed using Taqman Environmental Master Mix and symbiont genus-specific and coral species-specific primers and probes targeting the actin gene (Cunning & Baker, 2013; Cunning et al., 2015). In addition to collecting tissue samples, the photochemical efficiency of symbionts within coral cores was also assayed before, during, and after heat stress using an imaging-PAM fluorometer.

Full methodology described in Buzzoni, et al. (2023) (DOI: 10.1007/s00338-023-02428-x)

All imaging-PAM and qPCR data were analysed in RStudio V4.2.1 (R Core Team, 2022). qPCR data were filtered to exclude samples lacking two technical replicates which amplified with Ct values under 40. Ct data were used to calculate the relative abundances of symbiont genera in tissue samples (relative to all Symbiodiniaceae present and relative to coral host cells) using the stepOneR package (Cunning, 2018). Ct data were also adjusted for differences between symbiont genera and coral species in target locus copy number, DNA extraction efficiency, and probe fluorescence intensity.

The Supplemental File "Ct_corrections_table.pdf" contains correction coefficients fed into StepOneR software along with qPCR Ct data. These correct for differences in host and symbiont DNA extraction efficiency and gene copy number, and for differences in fluorescence of target-specific probes.

- Imported original file "qPCR_IPAM.csv" into the BCO-DMO system.
- Flagged "NA" as a missing data identifier (missing data are empty/blank in the final CSV file).
- Converted latitude and longitude values to decimal degrees and rounded to 4 decimal places.
- Converted the date column to YYYY-MM-DD format.
- Replaced the abbreviated species name with the full genus + species name.
- Renamed fields/columns to comply with BCO-DMO naming conventions.
- Saved the final file as "918220_v1_qpcr_ipam.csv".

NSF Award Abstract:
Climate change represents an existential threat to coral reef ecosystems worldwide, with coral bleaching driven by continued ocean warming presenting the most pressing challenge to the persistence of these ecosystems over the next few decades. Given the severity and urgency of this threat it is critical to investigate mechanisms by which some corals might survive warming, assess the degree to which this is happening on reefs, and apply these discoveries to inform conservation interventions that might improve survival trajectories wherever possible. This project aims to fulfill these objectives by testing whether reef corals in the Caribbean are undergoing shifts in their algal symbionts in favor of more heat-tolerant types, what the consequences of these shifts might be for coral reef ecosystems, and the way in which we might use this information to help conserve them. Scientific objectives will be leveraged to improve the effectiveness of reef restoration efforts in the Caribbean by applying findings to ongoing intervention trials which aim to seed outplanted corals (both adult fragments raised in nurseries, and sexually derived coral recruits) with heat tolerant algae that are climate-resistant. It also takes advantage of emerging opportunities at two major public aquariums to highlight the plight of coral reefs to engaged public audiences primed to receive this message and learn about the role of science in both understanding and mitigating the problem. Finally, numerous high school, undergraduate, and graduate students will receive mentorship during this project, helping to train the next generation of marine scientists.

This project tests whether continued climate warming is causing heat-tolerant algal symbionts (such as Durusdinium trenchii) to become increasingly common on coral reefs in the Caribbean. Understanding the changing symbiotic "milieu" in the region, the processes underlying the spread of D. trenchii, and the consequences of this spread, are very timely questions that have the potential to help us understand future reef states. This project will: (1) Manipulate coral symbioses in the laboratory, including a number of Caribbean coral species never before attempted, to assess in a standardized way their relative ability to acquire heat-tolerant symbionts; (2) Outplant corals with manipulated symbiont communities to reefs to assess real-world ecophysiological tradeoffs to heat tolerance, such as reduced growth rate; (3) Introduce heat-tolerant symbionts to coral colonies in the field using tissue implants in order to understand environmental controls on the persistence or loss of introduced symbionts; (4) Evaluate transgenerational feedbacks in the symbiotic milieu by investigating the roles of temperature and D. trenchii availability on the acquisition and establishment of these symbionts in newly settled coral larvae; and (5) Quantify changes in the incidence and relative abundance of heat-tolerant symbionts in the Caribbean over the last ~20 years using unique archived samples dating back to 1995-2002 from Florida, Bahamas, Belize, and Bermuda.

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.