ECR Spotlight – Jennifer Mallon Free

Jennifer Mallon

How did you become interested in biology?

It was through SCUBA diving that I first became interested in marine biology. Although I had never thought about diving before, I was lucky enough to be invited on a scuba dive by a local photographer and her group of dive professionals at a unique local spot known as ‘Manta Point’ in Indonesia. With a first underwater experience alongside a family of majestic giant manta rays, I was inspired to immediately change the degree choice on my university application from English literature to marine biology. That was over 15 years ago, and I have not looked back since. Nature had always been captivating for me, but the underwater experience was like magic. I was also fascinated that when I tried to look up the answers to my questions on corals and reef organisms, often the information was simply not out there. It still seems bizarre to me that there are so many fundamental knowledge gaps in the basic physiological processes of corals and other reef organisms, yet they are becoming extinct before we even have the chance to understand them. From this love of SCUBA and the underwater world, I began to ask myself more questions about the biology of these systems, but it was really a love of being underwater that got me into the field.

Describe your scientific journey and your current research focus

I like to think of myself as a non-conventional academic, and my journey into graduate school and research was not typical either. As the first in my family to attend university, I had little idea of what to expect. After earning my undergraduate degree at the University of St Andrews in Scotland, all I wanted to do was to spend more time underwater, so I moved to Mexico to train as a dive instructor. Diving the same reefs every day, I became deeply familiar with individual coral colonies and the fish or other creatures that lived in specific nooks and crannies of the reef. They felt like old friends, and it was distressing to witness their rapid decline through disease and bleaching. When I saw an advertised biologist position to initiate a reef restoration project in the local town of Akumal, I jumped at the opportunity. At first, the idea wasn't taken seriously, but with support from the local dive community, we installed the first coral nurseries on Akumal's reefs. Working alongside local divers, fishermen and conservationists, we fragged hundreds of coral outplants and reproduced juvenile corals from spawning colonies, all on a shoestring budget. I collaborated with the Coralium Laboratory at the National Autonomous University of Mexico and became inspired by their work to return to school for my graduate studies. When the scholarship I applied for fell through, I decided to self-fund my PhD through a series of small grants and sponsorship by non-profit organizations. In my final year, I got a grant from the University of Glasgow for a 6-week visit to the Smithsonian Marine Station in Florida, and supplemental funding from Coral Conservation Society. This led to a 6-month postdoc fellowship, during which I conducted experiments on coral deoxygenation stress. I later received a US-UK Fulbright Scholar Award, which I completed in the Florida Keys. Now, as a postdoctoral researcher based at the National Coral Reef Institute, Nova Southeastern University, my work is focused on the interactions between corals and crustose coralline algae and turf algal communities, key components of the reef benthos in Florida.

How would you explain the main findings of your paper to a member of the public?

Deoxygenation is emerging as a major threat to coral reefs that has been somewhat overlooked compared to ocean warming and acidification. Coastal deoxygenation, or reduced seawater dissolved oxygen concentrations, can be caused by pollution and nutrients and is also exacerbated by warming temperatures. Warmer water holds less oxygen, and on tropical reefs, sudden drops in oxygen levels can severely stress coral. In some extreme cases, entire reef communities have died over rapid time scales in response to oxygen depletion. This is because corals, like all animals, need oxygen to survive. There is now a growing body of research looking at the fatal effects of deoxygenation on corals, but the precise thresholds and effects of deoxygenation-induced stress, or hypoxia, are not well understood. In our study at the Smithsonian Marine Station, we simulated moderately low-oxygen conditions, above what we think are the likely thresholds for coral mortality to occur, so that we could measure the nonlethal effects of low oxygen on different coral species. Over 2 weeks, we measured changes to coral health through visual assessment and direct measurements of coral photosynthesis and respiration. Throughout the 2 weeks of exposure to deoxygenation, the corals did not show any signs of stress, and there was no bleaching or mortality in the three species we tested. However, we found that the corals shifted their rates of metabolism – that is, photosynthesis and respiration – and this is likely how they managed to survive the low-oxygen conditions. Through switching their energetic budgets, the corals were able to withstand 2 weeks of low oxygen conditions. So, what does this mean at the reef scale? Well, potentially, coral stress caused by exposure to low oxygen in the field might be undetectable during traditional reef monitoring because they do not show any signs of stress that can be visually observed. Importantly, the change in the corals’ metabolism that we measured might affect their long-term growth potential, as energy derived from photosynthesis and respiration is used to build coral skeletons. This has important ramifications for overall reef structural growth and integrity, since reefs are made up of coral skeletal material.

What do you enjoy most about research, and why?

Coral reef science is relatively young, considering that SCUBA diving and underwater cameras have only become accessible in the last 70 years or so. There is still so much to be discovered about coral reefs, their biology and how they work. Given the dramatic decline in coral populations worldwide and the risk of extinction they are facing, the urgency of this research can be very exciting. Another element of research that I love is the variability and unpredictability; every day as a researcher is different. My work involves the typical scientific tasks you might expect – data collection, lab work, statistical analyses – but beyond that, research encompasses so many other skills and activities. There's always something new to learn, and it's impossible to be bored for long. I collaborate with diverse groups: world experts and scholars, students, conservation practitioners and citizen scientists. I also fundraise, do outreach, design materials, develop new equipment, mentor and give public talks… the list goes on. At times, balancing all these aspects can feel overwhelming, but for someone like me, who finds it hard to focus on a single task for too long and thrives switching between projects, it's the perfect fit. The constant change gives me a sense of freedom in my work that I truly love. No two experiments are ever the same, and the fieldwork almost never goes to plan. Learning to be flexible and adapt to different conditions is fun, and for me the unpredictability makes research even more exciting.

What is the most important piece of equipment for your research, what does it do and what question did it help you address?

The research tool I am most excited about is Coral Observer (www.coralobserver.com), the web-based app I developed to streamline coral spawning data collection and broaden participation in coral spawning monitoring efforts. The app is free and easy to use. It was designed to encourage citizen scientists and reef enthusiasts from all backgrounds to get involved in recording coral spawning events across Caribbean reefs. Coral spawning patterns and timings are difficult to predict. We know that corals synchronize their spawning for maximum reproductive success, and that the lunar cycle plays a key role in timing. However, we still don't fully understand how spawning varies across different locations or how environmental factors influence its exact timing. One of the biggest challenges in studying coral spawning is that corals generally spawn after the sun has gone down. Night dives can be logistically demanding, costly and time-consuming, and many reef sites remain unmonitored. In Akumal, we had guidance from the Coralium lab's database on nearby sites to help us estimate when to start looking for spawning. Even with this knowledge, it still took six consecutive nights of diving to pinpoint the exact timing of spawning on our first attempt. Coral Observer was created to support the Caribbean-wide spawning database by making data collection more accessible and widespread. By crowdsourcing observations, we can gather more information on when and where corals are spawning. This will help scientists better understand and predict coral spawning patterns, ultimately informing conservation efforts and reef management strategies.

Do you have a top tip for others just starting out?

I think it is important to stay firm on your path. As a research scientist or student, your ideas should be novel and may be unconventional. It can be common as an early career researcher to face a lack of support when pursuing your own research interests. Remember, it is likely that you know your research project better than anyone else. Constructive feedback from mentors and experts is invaluable, but it is equally important to trust your own intuition and follow through on your ideas, especially if you are exploring something new or using a novel approach. Some of the most groundbreaking discoveries come from those willing to push boundaries, to think outside of the box, and to ask questions that others haven't considered. Science is rarely linear; it's often a messy, trial-and-error process with unexpected results. One of the best habits to develop is documenting everything, keeping detailed notes, and taking photos and videos of experiments, fieldwork sites and findings. Sometimes it is the smallest, most seemingly inconsequential detail that can explain an unexpected result or shape the next stage in methodology development. Most importantly, persistence is key. As a scientist it is important to keep curious, embrace challenges and not to be discouraged by setbacks. Every step, even the missteps, contribute to progress.