Heithaus

Another day, another milestone

A predator’s role in storing carbon

Publication specs

Title: Predators help protect carbon stocks in blue carbon ecosystems

Authors: Trisha B. Atwood, Rod M. Connolly, Euan G. Ritchie, Catherine E. Lovelock, Michael R. Heithaus, Graeme C. Hays, James W. Fourqurean, Peter I. Macreadie

Journal: Nature Climate Change

Year: 2015

When you think about carbon (C) storage in an ecosystem, you may think about a lush tropical forest sucking up carbon dioxide from the atmosphere. What isn’t considered as often is coastal marine ecosystems, which take up C 40 times faster than tropical forests. An estimated 25 billion tons of C is buried in vegetated coastal habitats like seagrass meadows, mangroves, and salt marshes, making them the most C rich environments in the world. Degrading these “blue carbon ecosystems” releases C into our atmosphere, fueling climate change. But did you know that losing predators like sharks within these environments also indirectly leads to the release of C?

One example of this comes from Western Australia where sharks influence how often herbivores like dugongs and sea turtles feed in a given time period. These grazers like to eat in places where there are very few tiger sharks waiting to attack them. In habitats where sharks are present, they spend more time watching their backs. This means that less seagrass is being consumed, and in some cases is only being cropped. In the areas where sharks are present and there are fewer grazers, the seagrasses are mostly slow growing species, which promotes the storage of C since it is not breaking down quickly. In other words, where the abundance and behavior of herbivores are being controlled by predators, growth of vegetation is enhanced, which leads to increased storage of C.

Scientists don’t know the total global area affected by the loss of predators. However, if only 1% of the vegetated coastal areas were to be affected, about 460 million tons of C would be released, equivalent to the emissions from 97 million cars. In order to protect these blue carbon ecosystems, balanced conservation efforts will need to occur where the habitat, predators, and herbivores are protected together.

Dining in fear: the influence of predator and prey behavior on the health of coral reef ecosystems

Publication specs

Title: Reefscapes of fear: predation risk and reef heterogeneity interact to shape herbivore foraging behaviour
Authors: Laura B. Catano, Maria C. Rojas, Ryan J. Malossi, Joseph R. Peters, Michael R. Heithaus, James W. Fourqurean and Deron E. Burkepile
Journal: Journal of Animal Ecology
Year: 2015

Imagine: you’re quietly enjoying your breakfast when suddenly a lion barges through your front door. Do you continue eating? Run for cover? The answer for you, and other potential prey, is pretty clear. For small, plant-eating fish living on coral reefs, this is a constant threat. So much so that even just the fear of a potential predator, like sharks and grouper, can alter their behavior. While that may seem obvious, a recent study has revealed something not quite so intuitive – this fear is actually good for the entire coral reef ecosystem.

The findings of this study suggest something rather surprising – without predators, herbivorous fish cannot fulfill their normal function on the reef. Reefs come in a variety of structures and are comprised of a multitude of interdependent organisms. The feeding behavior of these fish, like surgeonfish and parrotfish, are influenced by both the structure of the reef and their predators. In the absence of predators, or in this case a grouper decoy, the fish ate almost two times more seagrass than when the decoy was present. In areas with and without complex reef structure, the fish did not eat as much when the grouper decoy was present.

Complex reef habitats don’t offer easy escape or shelter, which means that in areas with predators lurking, fish spend more time trying to find safe spaces rather than grazing. According to these findings, herbivorous fish concentrate their feeding to areas where they are less likely to encounter a roving predator, leaving more space for coral to settle, grow, and thrive. Reefs without predators encourage grazing across larger areas, leaving less open space for young coral to survive. This study suggests that this interplay – between predator, prey, and ecosystem – is crucial for healthy reefs.

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 would likely be eating where they are safe from predators, there should be 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,Untitled 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

Below are data produced from last year’s shark mission: a shark swims by the remote camera and shows up on the multi-beam imaging sonar.

© FIU, Dr. Kevin Boswell

Mission Overview

Dr. Kevin Boswell

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 to understand the impacts on the benthic community.

 

 

 

Dr. Michael HeithausDr. Michael Heithaus, Dean of the College of Arts, Sciences & Education & Global FinPrint’s co-lead principal investigator, is co-leading this mission. His lab will set BRUVs to provide data on fish behavior in the presence & absence of sharks. Setting the BRUVs is also part of Global FinPrint, which attempts to assess the presence of sharks & rays on coral reefs all over the world, understand the factors affecting their distribution, and inform conservation actions for threatened species.

 

 

 

TUS

 

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 this mission via the Teacher-Under-the -Sea program. This work would not be possible without the help of our amazing Aquarius Reef Base staff and the support of the Paul M. Angell Family Foundation.

 

 

Join the adventure live online

Aquarius Reef Base Twitter #Angellsharks

SEAS Twitter #sharksFIU

Global FinPrint Twitter #count2save

Meet the Team

Alain Duran – Science Team Lead

  • Ph.D. candidate at FIU.
  • Studies the effect of biotic and abiotic drivers of herbivorous fish-algae interactions and their impacts on coral reef dynamics and conservation.
  • Works on the dynamics of coral reef fish, particularly herbivores.

Benjamin Binder - Scientist

  • Graduate student at FIU.
  • Focuses on the community wide effect of fish spawning aggregations (FSA) in the South Florida region and the spatiotemporal patterns of FSA formation.
  • Tools of his trade include various fisheries sonars, which will be used extensively during the mission. 

Frances Farabaugh - Scientist

  • Ph.D. student in the Heithaus Lab at FIU and is involved with the Global FinPrint project.
  • Focuses on behavioral ecology of marine predators.
  • Hopes to elucidate the role sharks play in structuring reef communities by investigating predation risk effects and the functional redundancy of top predators. 

Roy Bartnick - Science Translation Specialist, Teacher-Under-the-Sea Program

  • Currently working on his Ph.D. dissertation in Educational Leadership at Capella University, Minneapolis, MN.
  • Goal is to seamlessly blend STEM across the curriculum at the elementary school levels in hopes of fostering a love of learning while providing students the ability and opportunity to apply their knowledge to real world applications on a global community level.
  • Will mentor the FIU student teacher, Carlos Calle, and lead many of the educational programs conducted aboard Aquarius through collaboration with Skype in the Classroom.

 

Carlos Calle – Science Translation Specialist, Teacher-Under-the-Sea Program

  • Studies elementary education at FIU and is completing his internship at Norman S. Edelcup K-8 Center in Sunny Isles, Florida.
  • Has a special interest in conducting experimental research in natural sciences and will work hand-in-hand with the science team.
  • Will lead many of the educational programs conducted aboard Aquarius through collaboration with Skype in the Classroom. 

Cathy Guinovart – Aquarius Reef Base Education and Outreach Coordinator

  • Senior pursuing a Bachelor’s degree in Sustainability and the Environment.
  • Started a student-run organization at FIU called “Age of Aquarius”, which is dedicated to teaching the community about the value of Aquarius and the oceans as a whole. 
  • Schedules all virtual field trips for this mission and facilitates shore base live links with Carlos Calle.