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

Adult culture and spawning

Adult Nematostella vectensis sea anemones were collected from a salt marsh in Brigantine, New Jersey in the fall of 2020, and spawning was induced. Larvae (n = 1 cohort with mixed parentage) were then cultured to the planula stage (3 d post-fertilization) for experimentation. An aquarium population of adult Galaxea fascicularis colonies (n = 9 females, 10 males) spawned during August 2023 at Carnegie Science (Baltimore, MD, USA), yielding a cohort of planulae (n = 1 cohort with mixed parentage) that were used in experiments within 48 h. Adult Porites astreoides colones (n = 20) were collected in Bermuda (32°22′13″N, 64°44′27″W) during July 2023. Brooded planulae (n = 4 cohorts) were collected and maintained in culture for ~ 48 h.

At the time of use in experimentation, larvae from all 3 species were in the planula stage and would become competent to settle within 72–96 h (Hand and Uhlinger 1992; Goodbody-Gringley et al. 2018; Wei et al. 2023). Artificial seawater was used for culturing and experimentation for N. vectensis and G. fascicularis, while flow-through, natural seawater facilities at the Bermuda Institute for Ocean Science were used for P. astreoides.

Dissoved Oxygen Treatments

Stage-matched, swimming planulae of N. vectensis, G. fascicularis, and P. astreoides (N = 1,200–2,400 larvae species-1) were divided into six replicate groups (three normoxia/control and three hypoxia) and exposed to 6 h of normoxia (dissolved oxygen (DO) = 6.8–8.69 mg L-1) or severe hypoxia (DO = 1.58–1.8 mg L-1; seawater deoxygenated using N2 gas) inside sealed glass jars (500 mL) overnight from 21:00 h to 03:00 h the following day. The jars were placed at the ambient culture temperature for each species (N. vectensis: 18°C; G. fascicularis: 27°C; P. astreoides: 28°C). At the end of the treatment period, the jars were uncapped and groups of 20–30 larvae (N = 60–90 larvae treatment-1 species-1) were transferred to 1.5 mL tubes without seawater for storage at -80°C until processing

Measurements

Detailed methods can be found in the associated publication (Glass and Barott 2025).

• Ash-free dry weight (AFDW; i.e., organic biomass) of larvae and juveniles was quantified from burned, dried tissue.
• Chlorophyll content within algal endosymbionts of larvae and juveniles was quantified via spectroscopy.
• Heat tolerance of P. astreoides larval symbionts was quantified via changes in photochemical yield (collected with a pulse-amplitude-modulation (PAM) fluorometer) over time at 36°C.
• Heat tolerance of larvae was quantified via visual observation of survival over time at 36°C. Photochemical yield of P. astreoides larvae and juveniles as quantified using a pulse-amplitude-modulation (PAM) fluorometer.
• Metabolic rates of larvae and juveniles was quantified via respirometry.
• Protein content larvae and juveniles was quantified via Bradford assays.
• Larval settlement rates were quantified via brightfield microscopy.
• Larval and juvenile sizes were quantified via brightfield microscopy.
• Larval swimming behavior immediately following the oxygen treatments was quantified via imaging using iPhone 14 (Apple).
• Larval and juvenile symbiont density was quantified via flow cytometry. 

Full details regarding data and statistical analyses are present in Glass and Barott (2025), Supporting Information. RStudio with R version 4.2.1 was used for all analyses (RStudio Team 2020). All values are expressed as averages rounded to appropriate significant figures ± standard error of the mean (SEM), and all original data is attached as supplemental files and published (Glass, B., & Barott, K. 2024), as referenced in the related datasets section. The code used (Glass, B., & Barott, K. 2024) is listed in the related publication section. 

- Imported "AFDW_data.csv", "Chlorophyll_data.csv", "Heat_tolerance_PAM_data.csv", "Heat_tolerance_survival_data.csv", "PAM_data.csv", "Photosynthesis_data.csv", "Protein_data.csv", "Respiration_data.csv", "Settlement_data.csv", "Size_data.csv", "Swimming_behavior_data.csv", "Symbiont_density_data.csv", "Treatment_seawater_conditions_data.csv" into the BCO-DMO system
- Concatenated all datafiles with their original file names in the "Data_filename" parameter
- Exported file as "964162_v1_performance_early_life_stages.csv"

NSF Award Abstract:

Ocean warming driven by climate change has led to staggering losses of coral on reefs worldwide and is now among the most pressing of stressors threatening the survival of coral reef ecosystems today. As marine heatwaves associated with ocean warming become increasingly frequent, it is urgent to understand if and how reef-building corals will be able to respond to these repeat stress events and thus survive in a rapidly warming ocean. To address this problem, this project is investigating how corals on the reef respond to recurring marine heatwaves in order to identify if repeat exposure to heat stress promotes coral tolerance of higher temperatures via acclimatization or instead leads to the accumulation of stress and thus reduced performance and survival following future stress. The results of this study are critical for understanding how the current generation of corals will respond to increasingly warmer oceans, and whether acclimatization will buy enough individuals sufficient time for adaptation to occur and promote coral persistence into the future. In addition, this project is training students from secondary schools through advanced postdoctoral researchers in global change biology and ecology. Specifically, the investigators are increasing access to research opportunities for undergraduate students by developing a new hands-on course-based undergraduate research experience (CURE) in Global Ocean Change Biology that will reach hundreds of students per year. Outreach efforts include creation of hands-on coral reefs and climate change activities for incoming first-generation, low-income undergraduate students and a professional development program to train middle and high-school teachers to deploy these climate change activities in their classrooms in the Philadelphia Public School District.

Acclimatization following exposure to sub-lethal heat stress may be an important protective mechanism for corals to survive a changing climate. However, the role of environmental memory of marine heatwaves in driving acclimatization or, conversely, stress accumulation and sensitization of reef-building corals is not well understood. This study is addressing this question using a combination of in situ and mesocosm experiments to assess the cellular, organismal, and ecological consequences of repeat heatwaves on corals with contrasting bleaching histories. Specifically, the researchers are monitoring adjacent conspecific pairs of bleaching-susceptible and bleaching-resistant individuals of two reef-building coral species in Hawaii, Montipora capitata and Porites compressa. These corals have been monitored for over 7 years through multiple bleaching events and are being used to test the hypothesis that environmental memory of marine heatwaves differentially alters coral thermal performance due to phenotypic variation in acclimatization ability within and between species. This work is identifying whether the bleaching thresholds of corals with different bleaching histories varies through time, and the consequences of these phenotypes on coral calcification, survival, and population size structure are being assessed using a combination of benthic surveys, photogrammetry, and in situ growth measurements. The influence of environmental memory of heatwaves on coral physiology is being assessed using thermal performance curves to determine how the thermal optima of respiration, photosynthesis, calcification, and host intracellular pH change (or not) over time (e.g. ambient vs. heatwave years) and if that response differs between corals with contrasting bleaching phenotypes. Finally, the contribution of algal endosymbionts to acclimatization is being evaluated by exposing corals to a range of increasing temperatures in experimental mesocosms, potentially uncovering differences in the degree of acclimatization or sensitization for host vs. symbiont traits in corals with high fidelity (P. compressa) vs. cosmopolitan (M. capitata) symbiont associations. By understanding of the phenotypic diversity in thermal performance across biological scales, this research improves predictions of coral persistence in the face of the ongoing climate crisis.

This project is supported by the Biological Oceanography, Integrative Ecological Physiology, and Ocean Education Programs.

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.