Coral Thermal Tolerance and Global Warming Mitigation Strategies

Global warming is considered to be the most severe threat to coral reefs. This is evident in an increase of frequency and severity of global coral bleaching events (loss of coral symbionts due to heat stress) leading to coral death and reef degradation. The current focus of the MABEE lab is to find ways to mitigate the impact of global warming on corals by either strengthen corals to resist marine heat waves or by altering the environment to reduce ocean temperatures or high light during thermal stress.


  1. AU Coral (NSF-funded, since 2023): The MABEE lab is one of very few labs that explores the potential utility of artificial upwelling (AU), a geoengineering technology that uplifts cooler deep water to the warm surface waters during heat stress events. This reef management tool could offer a localized mid-term solution to allow corals a more gradual adjustment to global warming. The overarching goal of the AU Coral project is to provide an understanding about how AU could be used for surface water cooling by identifying AU scenarios (depth, intensity) that mitigate coral bleaching effectively, while imposing minimal risk of unwanted side effects. We hypothesize that this can be achieved by creating daily short-term thermal refugia via pulsed AU (e.g., <5h/day) with waters from the intermediate and lower euphotic zone (e.g., ~30-100 m). Using the BMMF facility, we are investigate immediate and lasting effects (legacy) of AU on coral physiology during heat stress. Furthermore, we will assess reef community responses to AU during heat stress. Chloe Carbonne is post-doc of this project.

Student interns involved:

  • Gabriel Rodriguez-Roig - undergraduate [REU], Florida Int. Univ., USA, 2023
  • David Yo Jen - undergraduate [REU], Univ. of California LA, USA, 2023
  • Hannah Green - undergraduate, Eckerd College, FL, USA, 2023
  • Jennifer Monk - undergraduate, Univ. of Nottingham, UK, 2023


  1. ENCORE (HSFI-funded, since 2022): The overall goal of this collaborative project is to address coral resilience, acclimatization, and adaptation to a warming ocean. We use Bermuda as a high-resolution test bed with a broad comparison of our Atlantic (Bermuda) site with one Pacific (Hawaiʻi USA) and one Caribbean (Cayman Islands) reef site, enabling broader geographic applicability of our results. The questions addressed include:
  2. A) How do differences in environmental conditions experienced across a range of geographic locations impact the resistance and resilience of corals to thermal stress? What are the molecular and cellular mechanisms that enable coral resilience?
  3. B) What are the magnitudes and duration of thermal exposures that provide beneficial stress conditioning in corals? How does stress conditioning impact cellular and molecular state? How long do beneficial or thermally tolerant phenotypes last?

To address these questions, a combination of in-situ and experimental manipulation studies using mesocosms (e.g., BMMF) and / or aquaria is used, in conjunction with physiological measurements and molecular analyses. The study is conducted in collaboration with Samantha de Putron (BIOS), Gretchen Goodbody-Gringley (CCMI) and Hollie Putnam (URI). Post-doc of the project is Brett Jameson and participating PhD students are from the Putnam Lab.

Student interns involved:

  • Cade Meyer – undergraduate [REU], Iowa State Univ., USA, 2023
  • Annabel Catherine Burcham – undergraduate [REU], Univ. of North Carolina, USA, 2023
  • Ruth Mello-Cann – undergraduate, Brigham Young Univ., Utah, USA, 2023
  • Talia Barry – undergraduate [REU], Univ. of Tampa, FL, USA, 2022
  • Jada Brown - undergraduate [REU], Univ. of Tampa, FL, USA, 2022
  • Kaylee Cooper, Fall REU intern, Univ. of California, Los Angeles, USA, 2022
  • Min Han – undergraduate [REU], Univ. of California, Irvine, USA, 2022
  • Daque Davis - undergraduate, Bermuda College, 2022
  • Elanor Dunleavy – undergraduate, Penn State Univ., 2022 & 2023



  1. AU Reef (DFG-funded, 2017-2019). This award allowed to conduct some preliminary studies on the potential use of artificial upwelling (AU) during heat stress on coral physiology (manipulation experiment) and on surface waters biogeochemistry (modelling approach). While lead-PI Yuming Feng at GEOMAR, Helmholtz Center for Ocean Research, Kiel, Germany, conducted the modelling study, the MABEE lab conducted a laboratory-based experiment assessing whether pulses of deeper cold water intrusions into shallow reefs during heat waves could prevent coral bleaching using deep water collected by the RV Atlantic Explorer in 50 and 100 m depth (Sawall et al. 2020; see also ). This study provided a first indication about the potential utility of artificial upwelling to prevent coral bleaching, which is now further explored under the AU Coral project.

Students involved: Moronke Harris, 2018), Hannah Lampit.

Project Contact

Dr. Yvonne Sawall
Assistant Scientist


School of Ocean Futures at Arizona State University

Asst Professor
, School of Ocean Futures Faculty

Assistant Professor, School of Life Sciences
Senior Global Futures Scientist, Global Futures Scientists and Scholars
Asst Professor, School of Ocean Futures Bermuda Faculty