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

Sea Anemone Collection and Culture

Adult Nematostella vectensis sea anemones were collected from the JC NERR near Brigantine, New Jersey, USA in 2020. Spawning was induced approximately twice per month using a standard method for Nematostella vectensis (Hand and Uhlinger 1992; Stefanik et al. 2013). Larval anemones were retained in culture dishes and advanced to the adult stage over 2 years, then spawned in individual cups to identify female and male animals for use in the experiment. 

After seven days of acclimation, adult anemones were distributed across 6 tubs (N = 3 tubs per DO treatment: normoxia/control and hypoxia) with 15 females and 14 males in each tub (N = 87 animals per treatment). Next, spawning was induced on day 7 of acclimation to clear anemones of developing gametes (Glass, Schmitt, et al. 2023; Rivera et al. 2021). Total water changes were then performed for each tub, and animals were placed back in ambient culture (i.e., normoxia) for the start of the experimental period (i.e., experimental day 0). 

Hypoxia Treatments

Over nights 5, 6, and 7 of the experimental period, adult anemones were exposed to either normoxia (i.e., controls; DO = 7–10 mg L−1) or hypoxia (DO = 0.5–1.5 mg L−1) for ~12 h night−1. Nitrogen gas was used to deoxygenate the water in a glass jar filled nearly to the brim (500 mL; Ball Corporation, Westminster, CO, USA) to a value of ~1.5 mg L−1 (salinity corrected) as determined by a handheld DO probe (YSI ProSolo 626650; accuracy = ±0.02 and precision = 0.01 mg L−1; YSI, Yellow Springs, OH, USA). The anemones from 1 culture tub (N = 29 animals) were transferred with minimal culture water (containing no Artemia) into the jar, which was then topped off with anoxic 12 ppt ASW, capped, and covered with plastic wrap secured by a rubber band. This process was repeated for the 5 other jars, skipping the seawater deoxygenation step for the 3 normoxia jars, and all 6 jars were placed in a dark incubator at 18°C. While anemones were in the treatment jars, the (normoxic) seawater from the culture tubs was pooled and filtered (mesh size 100 μm) before being redistributed across the tubs to minimise block effects by tub and maintain water cleanliness by removing particulate waste, though this may have introduced a confounding factor and should be considered when interpreting the data.

After ~12 h, the jars were opened and a DO reading was quickly recorded. Anemones were then transferred back into their respective tubs with minimal water carried over from the treatment jars. Both animals exposed to hypoxia and controls were handled in the same manner.

Measurements

Detailed methods can be found in the associated publication (Glass et al. 2025).

• Dry weight of adult sea anemones was determined using a drying oven and lab balance.
• Respiration rates of adult and larval sea anemones were determined via respirometry using a PreSens sensor dish reader system.
• Female fecundity was determined by counting eggs imaged via brightifled microscopy.
• Male fecundity was determined by counting sperm via flow cytometry.
• Egg size was determined by measuring eggs in images collected via brightfield microscopy.
• Sperm mitochondrial membrane potential was determined using the fluorescent dye JC-1 analyzed via flow cytometry.
• Larval developmental success and settlement rates were determined via visual inspection under brightfield microscopy.

Full details regarding data and statistical analyses are present in Glass et al. (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. 2025), as referenced in the related datasets section. The code used (Glass, B., & Barott, K. 2025) is listed in the related publication section. 

- Imported "Combined_physiology_data.csv" into the BCO-DMO system
- Rename parameter names to remove units, in keeping with BCO-DMO style
- Exported file as "964167_v1_sea_anemones_measurements"

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.