Impacts of Sharks on Coral Reef Ecosystems
Do healthy reefs need sharks? This is one of the most misunderstood questions in coral reef ecology. Shark populations are declining due to habitat loss, overfishing, and other stressors. It is important to understand how these losses could affect the rest of the ecosystem.
Understanding the predator-prey interactions between herbivores and sharks is crucial for coral reef conservation. As top predators, sharks not only eat other fish, but they can also affect their behavior. In the presence of sharks, herbivorous fish may be concentrating their grazing to small, sheltered areas. Because these fish have to eat where they are safe from predators, there is more space to allow young coral to settle, grow, and thrive. In the absence of sharks, herbivorous fish may spread out their grazing randomly across large patches of algae, leaving few well-defined or cleared areas for corals to settle.
Fortunately, Florida International University has just the place to explore these dynamic questions, a lab under the sea – Aquarius Reef Base. From September 7th to 14th, a mission at Aquarius Reef Base will combine sonar with baited remote underwater video surveys (BRUVs), an experiment the first of its kind to bring these technologies together. Researchers on this mission strive to understand the direct impact of shark presence on herbivorous fish behavior as well as the indirect impact of sharks on algae communities. Combining these technologies:
- Provides a new way to study reef fish behavior
- Carves the path forward for future ecological research
- Offers insights that may lead to critical marine conservation outcomes
Dr. Kevin Boswell, an assistant professor of biology, is leading this mission. His lab will use low frequency sound to attract sharks around Aquarius. HD remote video combined with multi-beam imaging sonar will be used to quantify how fish behavior changes in the presence and absence of sharks. At the same time, grazing intensity by herbivores will be measured in order to understand the impacts of shark presence on the benthic community.
Dr. Michael Heithaus, Dean of the College of Arts, Sciences & Education as well as Global FinPrint’s co-lead principal investigator, is co-leading this mission. His lab will be setting BRUVs to provide quantifiable data on reef fish behavior in the presence and absence of sharks. Setting these BRUVs is also part of Global FinPrint, a larger project attempting to assess the presence of sharks and rays on coral reefs all over the world, understand the factors affecting shark and ray distribution, and inform conservation actions for threatened species.
In an effort to inspire the next generation of ocean enthusiasts and engage the public using innovative research technologies, a FIU student teacher, Carlos Calle, will take part of in this mission via the Teacher Under the Sea program. Roy Bartnick, 5th grade Math, Science, Social Studies and Robotics teacher at Chisholm Elementary in Enid, Oklahoma was also selected to be our Teacher Under the Sea during this mission.