Hi, Liv Williamson! Great to have you on ReefBites.
Liv is a Ph.D. student at the University of Miami, Rosenstiel School of Marine and Atmospheric Science. Her research focuses on possible interventions for increasing thermal tolerance and resilience in Caribbean coral juveniles. Read more about Liv’s work below!
Give an elevator pitch of what your research/project is about.
In order to reverse the rapid decline of coral reefs, scientists are testing diverse mechanisms by which corals might become more “climate smart”. One mechanism by which corals might rapidly adapt to climate change is modification of their association with endosymbiotic algae in the family Symbiodiniaceae. Simultaneously or at different points throughout their lives, corals can host several taxa of these algae, potentially helping them respond and adapt to changing environmental conditions. In the wild and in controlled laboratory settings, bleaching and recovery can shift symbiont assemblages in favor of thermally-tolerant Durusdinium (formerly Symbiodinium clade D) and raise a coral’s bleaching threshold by 1-2°C. However, to date no studies have attempted to manipulate symbiosis establishment in favor of Durusdinium in Caribbean coral recruits, despite the fact that most species start life as aposymbiotic larvae that take up new symbionts “horizontally” from the environment upon settlement to the reef. As such, we do not know how hosting Durusdinium affects Caribbean corals during their early life stages, and how this association might impact reef persistence and resilience across generations.
As a Ph.D. student at the University of Miami, my research addresses this knowledge gap by: (1) investigating the potential for boosting Durusdinium uptake during initial symbiosis establishment in aposymbiotic Caribbean coral recruits, (2) assessing the physiological and competitive trade-offs – in the lab and the field – of hosting different symbiont types during early ontogeny, and (3) determining whether increasing Durusdinium abundance in juvenile corals used for reef restoration efforts proves advantageous over the long-term. My results so far suggest that proximity to Durusdinium-dominated adult colonies increases the proportion of Durusdinium in recruits’ symbiont assemblages, and that hosting Durusdinium increases bleaching thresholds in juveniles. Next, I will begin field trials outplanting recruits with experimentally manipulated symbiont communities back to their natal reefs to test for fitness, resilience, and potential trade-offs in the wild.
Why is this research/project important and timely?
Scleractinian corals are ecosystem engineers, building reefs that support one quarter of all marine organisms and contribute billions of dollars to global economies each year through tourism, coastline protection, and fisheries. However, coral reefs are declining globally at an alarming rate, threatening the critical ecosystem services they provide. The combined and accelerating effects of multiple local and global stressors including ocean warming, ocean acidification, nutrient pollution, coastal development, overfishing, and predator and disease outbreaks may outpace corals’ natural capacity to adapt and evolve. In the Caribbean, coral cover has declined by 80% since the 1970s.
The primary cause of recent decline is coral bleaching, a phenomenon wherein stressful environmental conditions destabilize the symbiotic relationship that corals share with Symbiodiniaceae, a diverse family of dinoflagellates, resulting in ejection of the algae by the coral hosts. When corals bleach, they lose their most important source of nutrition and become white in appearance. If stressful conditions persist and symbiosis is not re-established, bleached corals may die. However, as explained above, algae in the genus Durusdinium may be particularly tolerant to thermal stress, allowing their hosts to survive and maintain symbioses under high temperatures.
Since coral spawning and settlement in the Caribbean coincides with the warmest ocean temperatures of the year, and because corals in their early life stages are particularly vulnerable to environmental stress and high mortality, it is important to understand if coral juveniles might become more thermally tolerant from the beginning of their lives by associating with Durusdinium. If so, intervention strategies can be focused on rearing coral juveniles to increase early uptake of Durusdinium, allowing them to survive the bleaching events that occur soon after they are born and have a better chance of making it to adulthood.
What is the broader impact and implication of your findings?
My research tests novel approaches for experimentally introducing thermotolerant symbionts into sexually-produced coral hosts at a key stage in their life history. If successful in Florida and the Bahamas, these strategies can be applied in other coral species and locations, creating “climate smart” recruits of a variety of coral taxa to seed reefs with new diversity and resilience. My findings will be directly integrated into active reef restoration programs in Florida (NOAA’s Benthic Ecology group) and the Bahamas (SECORE International) involving the collection of coral gametes, larval rearing, and outplanting of sexually-derived coral recruits. SECORE plans to outplant one million new recruits to reefs in several Caribbean nations over the next five years, many of which suffer from anthropogenic pressures associated with rapid population growth and urban development. Boosting thermal resilience in new generations of corals will help restore threatened populations and support local economies and livelihoods that depend on reefs for key ecosystem services.
Additionally, the live corals and experiments in my lab are excellent tools for teaching students and members of the public about how coral reefs contribute to the health of Florida’s coastlines and communities. Whether they realize it or not, Miami residents are impacted every day by our oceans. By actively engaging non-scientists in marine conservation issues, I hope they will feel inspired to take action on behalf of vulnerable animals and ecosystems that don’t have their own voices. I believe that involving young people and members of the South Florida community in ocean stewardship is essential for our collective future.
How did you come to work in this field/project?
My passion for marine science blossomed in the spring of 2016 when I participated in the School for Field Studies’ Tropical Island Biodiversity Studies program in Bocas del Toro, Panama. As a student researcher, I took regular snorkeling fieldtrips to study in a “living laboratory”. Amidst the beauty and diversity of the tropical marine ecosystem around me, I was most enchanted by the living backbones that supported this teeming underwater community: reef-building scleractinian corals. Their colonies of tiny polyps formed the substrate upon which everything else grew, clung, or crawled. I memorized each coral species’ scientific name and learned to identify it in the field.
I developed an ever stronger appreciation for the ocean as I discovered how important coral reefs were for supporting coastal communities. I befriended more and more Panamanians, and they showed me how the local reefs provide the seafood they eat, sustain their incomes by spurring tourism, and prevent erosion of their coastlines. I also learned how fragile these beautiful corals can be, and how their survival is threatened worldwide by climate change and other human activities.
When I left Panama and went back to New York City to finish my undergraduate degree, I knew I had to return to the reefs as soon as I could. I decided to pursue coral reef conservation as a career. In August 2017, I moved to Miami and started my Ph.D. with the University of Miami’s Coral Reef Futures Lab, planning to study the threats facing reef-building corals and investigate methods to enhance their resilience and survival.
What is your top graduate school life hack or survival resource?
I can’t stress enough the importance and underrated-ness of maintaining a work-life balance. Graduate students – and many other intelligent, hard-working, high-powered people – do a great job of stressing themselves out, but often do a worse job of caring for their own physical and mental health. To keep myself happy and healthy, I make sure I prioritize running 4-5 times a week, cooking good, healthy meals for myself, and taking time on weekends to NOT do work and do things for me.
Location of fieldwork; why choose this location?
I conduct the majority of my field work in Key Largo, FL and Eleuthera, Bahamas. In Key Largo, I work with a research team from the National Oceanic and Atmospheric Administration (NOAA) who have been monitoring populations of threatened Acropora palmata (elkhorn coral) and Orbicella faveolata for >15 years. While South Florida’s economy revolves around the reefs and the fisheries they support, the reefs in this area have been devastated by disease outbreaks and mass bleaching in recent decades, and they are in need of major reef restoration initiatives.
In Eleuthera, Bahamas, I work with researchers from SECORE International, Shedd Aquarium, the Perry Institute of Marine Science, the Nature Conservancy, and more. We are creating the “Bahamas Coral Innovation Hub” to test new technologies for upscaling coral reef restoration in the region.
Photos taken by: Josh Liberman, Eliza Thomas, and Ross Cunning.