"To the casual observer, seagrass meadows often appear to be uniform landscapes with limited structure. Oftentimes you could be passing over seagrass and not know it. Stick your face in the water and there’s a whole new world down there – the grass baffles the currents allowing small creatures to move about it.” - Madison Lytle
Seagrasses are underwater plants. Like plants on land, seagrasses have flowers, seeds, and roots, and they make their food through photosynthesis. Seagrass is often confused with seaweed, but seaweeds are algae that lack flowers, seeds, and roots. Madison Lytle is a PhD candidate in Dr. Jesse Jarvis’ Coastal Plant Ecology Lab at UNC Wilmington. With the N.C. Sea Grant and N.C. Coastal Reserve Coastal Research Fellowship, she’s researching the impacts of warming ocean temperatures and reduced light due to rising sea levels on seagrass structure, function, and distribution around the Rachel Carson Reserve.
With increasing water temperature due to climate change, the seagrasses experience increased respiration rates and need more sunlight to meet their metabolic demands. However, with sea levels rising, less light is reaching the seagrass at deeper depths. This is a concern because it may result in a shift in seagrass species meadow composition, distributions, range, and mortality. If we can understand how seagrasses are affected, temperature and light stressors can be managed by human intervention to protect and restore seagrass ecosystems.
In NC, there are two species of seagrass, Halodule wrightii (shoalgrass) and Zostera marina (eelgrass). Halodule is a tropical species that’s peak growing season is in the summer months when the water isn’t as clear, but the temperature is the best for growing. In the winter, Halodule is alive, but not actively growing. It’s like the seagrass is hibernating! Zostera is a temperate species that reaches its peak growing season in the spring. Madison explained that it has a large die off in the summer from the warm water temperatures. This die off translates to a large area of annual seagrass loss. Also, in general this species has been declining in N.C. over the past 60 years from climate change induced warming water temperatures.
When Madison first started her studies in the seagrass lab the lab’s interests were heavily focused on Zostera and why it was declining. During this time, she also learned that the other species of seagrass, Halodule, go into torpor during the winter. During winter field work, Madison observed Halodule in a very recessed state, the plant was still alive with tiny little green leaves, and it had what appeared to be a “huge” amount of belowground material built up.
“To me this didn’t look like the same type of “dead” that we see Zostera go through in the summer. This observation made me wonder what the species was doing in our system. In the winter, Halodule has to deal with another kind of temperature stress – the cold. We also didn’t see Halodule occupying the deeper waters where Zostera grows. In shallower areas the two species can grow together. So, this made me wonder why we weren’t seeing Halodule at deeper depths? Could it be light limited in deeper water?”
Each species has their own specific light requirement. So, Madison is studying how to find an estimate of Halodule’s light requirements. “The plant’s light requirements are needed to improve our understanding of how Halodule will respond to climate change and what the future species composition, distribution and abundance of seagrasses will be in N.C.” Her findings will impact management decisions. She explains that “current management actions are being made with the intentions to protect habitats into the future. We need to know if management goals are adequate. And we need to know how generalized a management goal can or cannot be. For example, do there need to be species specific or waterbody specific goals?”
Madison wrapped up her fellowship with N.C. Sea Grant and the N.C. Coastal Reserve in December 2023. Her next steps will be to publish the research so others can build off it. She also plans “to keep exploring mechanisms seagrasses use to overcome and adapt to stressors – what are these plants doing physiologically that is allowing them to cope with stressful environments they are living in.”
Keep reading to learn more about Madison’s marine science journey
How did you end up here? Why did you become a scientist? What drew you to the field?
“The movie Pocahontas - I thought Pocahontas was so cool for being able to communicate with animals, nature, and the spirits around her. She had a connection with nature that I could relate to as a child. I grew up on a farm. My family members were chickens farmers for Tyson and used the land for agriculture and oil tapping. I was raised in a family that used the land, relied on the land, and that made me appreciate what the land gives you and what you take from the land. I feel like we [humans] take things from or modify the environment and don’t appreciate it. We take advantage of our resources. I was interested in sciences that relate to the environment because it was a way to advocate for nature.”
What inspired you to start this career and what are you looking forward to?
“I started my career off studying marsh fish and oyster reefs and had a few influential mentors throughout that experience that helped me grow mentally, think critically, and become a better observer. They were passionate about their work, and it was easy to feed off that energy and get drawn in. I think one of my toxic traits is wanting to be a jack of all trades but master of none – I like to stick my nose in lots of research projects.”
What's your favorite aspect of your research?
“Working with and training undergraduates. They are constantly asking questions and really keep you on your toes and your mind sharp. It’s also fun to watch them grow and become more confident and independent over time. "
Tell me about your outreach you did as part of the fellowship (MarineQuest)
“I partnered with MarineQuest Sea G.E.M.S., an all-girls camp that aims to motivate females to go into a Science, Technology, Engineering, and Math (STEM) field. We exposed the campers to a “Day as a seagrass scientist”. There are two sides to science – the brawns and the brains. The brawns are the field work to collect and process the data, to carry out the long day, to get dirty, and sieve through dirty samples in the lab. The brains are used to craft the experimental design, analyze the data, and translate the meaning of the data to a bigger picture. The campers asked the question, "What is the seagrass abundance and species distribution during the peak growing season?” With the campers we kayaked to a seagrass meadow, quantified the seagrass abundance and species composition using two different methods. One method was in field observations of seagrass percent cover. The second was bringing seagrass back to the lab to collect some higher resolution metrics such as density and determining how tall the seagrass canopy was. We then visualized the data in graphs and related the content back to big picture seagrass concepts.”
What was a memorable time you had in the field?
“We had a graduate student that had amazing abilities to always see the coolest animals– it was just her luck. When she was with us on field days we would see the coolest things, most memorable was a manatee that just slowly cruised by us in a meadow. Other memorable animals were a fever of cow nose rays (probably 75-100), sea turtles, terrapins, sea horses, sea hares, dolphins, and the wild horses on the Rachel Carson Reserve.
The folks at the boat ramps are also memorable. The locals that spend time on the water really care. We always get approached and asked what we are doing. When they hear us say ‘seagrass’ they always have a “back in my day” seagrass story to share. They talk to us about a fisheries species they care about that live in the seagrass or are inquisitive on the condition of the grass and if it is doing alright.”
The North Carolina Coastal Reserve and North Carolina Sea Grant have established a research fellowship opportunity for North Carolina-based graduate students. The fellowship provides North Carolina-based graduate students with an opportunity to conduct research within one or more of the 10 sites that constitute the Coastal Reserve. Using the reserve sites as a research platform, fellows must conduct hypothesis-based projects that address coastal management issues specified by the Reserve. For more information and to see fellowship requests for proposal announcements, visit the fellowship page.
Read Madison's final report here.