And the winner of the LSU Three Minute Thesis Competition is…
Julie Butler is a PhD student in Karen Maruska’s lab in Biological Sciences at LSU. Last week, Julie stood in front of a packed auditorium in the Digital Media Center at LSU and fascinated us with a story about her research on the impact of man-made noises on fish behavior, reproduction, and acoustic communication – in three minutes flat. Julie came in first place out of nine finalists in the Three Minute Thesis competition (3MT) hosted by the LSU Graduate School. She won a prize of $1,000 and will be representing LSU at the Southern regional 3MT competition in March 2017.
In her research, Julie aims to understand how fish cope with increasing underwater noise levels. We were so intrigued by Julie's story about “Burt,” the African cichlid fish she studies, that we asked her to tell us more about Burt and why it matters whether and how man-made noise stresses him out. Julie, take it away!
“Acoustic signaling is fundamental to communication and crucial for reproductive and territorial behaviors in many species.” – Julie Butler
Guest post by Julie Butler
Meet Burt. He’s an African cichlid, Astatotilapia burtoni. Burt is a charismatic little fish that makes sounds during social interactions and is highly territorial. He’d rather die than abandon his home. Unfortunately for Burt, and for many other fishes, increases in human activities like shipping and oil exploration have caused underwater noise levels to be over 30 times louder than they were just a few decades ago. For comparison, think back to your last rock concert or Saturday night game in Death Valley. While you probably had a great time, chances are your ears were ringing afterwards from the roaring fans as Fournette ran for another touchdown.
Now imagine you live in that environment. No matter where you go, you can’t escape the noise. You may develop anxiety. You may start to lose your hearing. You may even change the way you communicate. This is what it’s like for fish that live in noise-polluted areas, like a shipping lane or harbor. So it’s important to understand how Burt, and other fish like him, communicate in and cope with this excess noise.
My dissertation research aims to understand how life in a noisy environment impacts fish behavior, physiology, development and communication, which has never been examined before in a single fish species. To do this, I place Burt and his comrades into specific social scenarios that take place in silent or noisy conditions. By taking advantage of their territoriality, I can force two males into a fight.
But noise makes a difference. Males that fight in noisy conditions take longer to resolve a fight than those fighting in silent conditions. It’s possible that this excess noise is a stressor or a distraction, just as you’d be distracted if there was a football game or rock concert happening in the middle of a class presentation. These altered territorial fights can have negative impacts on predator avoidance, energy use, and even affect reproductive physiology, for example resulting in a lower sperm count.
Now let’s meet Toni, a female A. burtoni fish. Toni is a mouthbrooding fish, meaning she carries her developing babies in her mouth for about two weeks during which time she starves herself. When exposed to excess noise, Toni is more likely to cannibalize her babies or release them prematurely. In addition, the developing larval fish, once released from the mother’s mouth, have higher mortality and a lower growth rate in noisy conditions. So this excess noise affects not just Toni’s maternal care behaviors, but also the developing fish inside her mouth.
Toni can see, smell, hear, and even feel Burt’s courtship, and she uses this information to make important social decisions, like when and with whom to mate. My research is examining how increased noise impacts Burt’s use of this multimodal signaling during social interactions. Interestingly, Burt increases his use of visual signaling when exposed to excess noise. He performs more visual displays and appears more brightly colored when in a noisy rather than silent environment. This suggests that these fish may try to overcome the noise by communicating in undisturbed sensory channels, like vision, touch, and smell.
So why should you care? The ability to communicate with those around you is important for all social animals, including humans. It’s how we learn, navigate, avoid danger, and find food or suitable mates. For much of the coastal world whose economy is dependent on shipping and fisheries, these effects extend not just to the fish inhabiting the waters, but also to the people and communities, like those in Louisiana, who are dependent upon these resources. For fish like Burt and Toni that rely on acoustic communication, anthropogenic noise can have devastating effects on their health, reproduction, and even species survival.
I hope this short introduction to Burt and Toni helps people to understand the potential consequences of human influences on fish. This is a worldwide problem that has been poorly studied, and much more research is still needed to understand how fishes cope with their ever-changing environment. The 3MT competition provided an opportunity for me to engage with non-scientists about my research and to spread the word about the negative impacts of human activities on fishes. I look forward to representing LSU at the regional competition in March and getting to share Burt’s story with more people.