What makes heat-tolerant Floridian corals tick?

CIMAS Assistant Scientist Anderson Mayfield previews his in-press article in Frontiers in Marine Science

These days it’s rare to hear good news, especially not when it comes to Earth’s ever-diminishing marine heritage; nevertheless, there are some environmental “success stories” to be cognizant of, one of which being the existence of resilient massive corals (Orbicella faveolata) on inshore reefs of the Upper Florida Keys (Figure 1). Although offshore conspecifics have generally perished on account of 1) climate change-induced bleaching (driven by concomitant seawater temperature rise) and 2) disease (inc. the now-rampant “stony coral tissue loss disease”), these corals continue to grow and reproduce under warm, turbid, and otherwise marginal conditions. To gain insight into just how this physiological resilience is established, former CIMAS researcher Dr. Catalina Aguilar first transported coral samples from two resilient inshore reefs (“Cheeca Rocks” & “The Rocks”) and an offshore “control” reef (“Little Conch”) to our research aquarium system, the “Experimental Reef Laboratory” of Dr. Ian Enochs (located at the University of Miami’s Rosenstiel School for Marine & Atmospheric Science). After exposing them to elevated temperatures (up to 33ºC) for several weeks, Dr. Aguilar sampled small biopsies, and we have since peered into the cells of these corals, as well as controls incubated at cooler temperature, to profile the genes and proteins they were synthesizing.

A structurally complex coral reef featuring resilient colonies of the scleractinian coral Orbicella faveolata in the Upper FL Keys (“Cheeca Rocks”). Photo by Anderson Mayfield.


Through this “multi-‘Omic” approach, we found that inshore genotypes are distinct from those offshore, and they host mutualistic, endosymbiotic dinoflagellates of the hypothetically more thermotolerant genus Durusdinium. With respect to their cellular biology, we uncovered that that these corals do not rely on traditional stress response proteins in their thermo-acclimation; such molecules are instead constitutively maintained in their cells (possibly as a result of life under compromised environmental conditions). Instead, the functional molecular data (i.e., gene mRNAs & proteins) seem to suggest that the means by which corals and photosynthetic dinoflagellates that inhabit their gastrodermal cells mobilize and translocate lipids (energy storage molecules) back and forth may fundamentally change at high temperatures (Mayfield et al. in press). Furthermore, it appears that both nature (environmental effects) and nurture (evolution) are at play; which is more influential in dictating coral persistence is a question we hope to address by analyzing the responses of these corals to “reciprocal transplantation” (inshore corals moved offshore & vice versa). Aside from these novel mechanistic findings, and the new questions they have raised, the data are also being used to develop models whereby we can use molecular signatures to identify resilient corals elsewhere (a topic broached in an early 2021 blog).

Citation: Mayfield AB, Aguilar C, Enochs I, Kolodziej G, Manzello DP (in press) Shotgun proteomics of thermally challenged Caribbean reef corals. Frontiers in Marine Science.

Anderson Mayfield, June 28, 2021