PhD Research

For my dissertation I am using molecular biological states (DNA methylation and lipidomes) to better elucidate the effects of nutrient stress on corals. Pollution from expanding human populations piles on extra stress on coastal ecosystems already dealing with numerous other stressors such as climate change and epidemics

Chapter 1: Nutrient Stress and Coral Health: Bridging Physiology, Holobiont Dynamics, and Molecular Mechanisms

For my first chapter I have written a narrative review paper detailing the complex nature of nutrient stress's effect on coral health and physiology and how molecular biological techniques can help us understand these effects mechanistically. Severity of eutrophication, ratios of key nutrients (primarilly nitrogen and phosphorus), nutrient sources, co-occurence with other stressors, and the effected coral species can all modulate the overall impact. Because of this, undertstanding these intricate dynamics is critical for stress mitigation and can have practical applications for restoration site selection. The mansucript for this section is currently under review, but a preprint of the paper can be found on EcoEvoRxiv: https://doi.org/10.32942/X2D38D

Phase I: Monitoring (chapters 2 and 3)

For my first phase, I monitored Porites corals on four reefs in Culebra, PR with differing nutrient regimes for a year in 2023. Over the course of this monitoring, we were lucky (in a scientific sense) to capture the effects of the 4th Global Coral Bleaching Event and find how it interacted with the nutrient conditions across our reefs. For my disseration, chapter 2 will cover the physiologic effects of the interactions between nutrient stress and the heatwave, and chapter 3 will go into the DNA methylation and lipidomic changes associated with the physiological responses. Writing for both of these chapters is currently underway.

The four sites off the Western coast of Culebra used for both phases of the project. Ahogada was found to have a nutrient pulse dynamic with the highest concentrations of nutrients, while the other three reefs experienced more consistent but moderate eutrophication.

Over the course of the monitoring, the degree heating weeks accumulated until they reached NOAAs threshold for the most severe alert where corals experience near complete mortality across the reef.

Phase II: Reciprocal Transplant

Following up the monitoring phase, I wanted to better understand how corals living in each nutrient regime would acclimatize to a novel regime. To do this I ran a reciprocal transplant experiment where Branching Porites corals were transplanted from each reef equally across every reef in the experiment. Image and data analysis for this phase is ongoing.

Study design for the reciprocal transplant experiment. Based on preliminary nutrient data, Ahogada and Punta Soldado had been expected to be the lowest nutrient reefs and thus circled in blue, but once the long-term data was collected we were able to see that Ahogada was the highest nutrient reef but experienced large seasonal nutrient pulses, while the other sites experienced lower but more chronic levels.

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