Impacts of Parrotfishes on Caribbean Coral Reefs

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Sadly, funding and logistics have constrained our work in the Caribbean, and we are no longer actively pursing these project. All of the Lab's current projects are in California.

Parrotfishes are major herbivores and detritivores on coral reefs that have an important functional role grazing algae and cyanobacteria that can otherwise overgrow corals, but they are also increasingly important fisheries for many communities. Places like Bonaire, Bermuda, and Panamá have banned parrotfish harvest altogether, while they are major fisheries on islands like Jamaica and St. Croix, US Virgin Islands. By improving our understanding of how the ecosystem roles of different parrotfish species vary across gradients in fishing pressure and on coral-dominated versus algae- and cyanobacteria-dominated reefs, we aim to help inform management strategies that balance immediate fisheries needs with long-term ecosystem resilience.

While parrotfishes primarily graze upon algae, cyanobacteria and detritus, some species occasionally eat live coral (corallivory) in addition to other food sources. While they graze coral infrequently, this predation can lead to partial to total mortality of coral recruits and established colonies, and may reduce coral reproductive output and growth. The challenge is that we currently have a limited understanding of the patterns and impacts of corallivory for corals.

To assess the net impacts of parrotfishes on coral reefs across the Greater Caribbean, our lab and collaborators have been studying the negative impacts of parrotfish corallivory and the positive impacts of their grazing on algae, detritus, and other resources. Our research has spanned across the Florida Keys, St. Croix, Bonaire, and Panamá. 

The roles of parrotfishes as coral predators

Our previous research on parrotfish coral predation has helped address questions such as: 
  1. How does the intensity of parrotfish coral vary across the Greater Caribbean in response to differences in parrotfish biomass, coral cover, and coral species composition? What coral species are commonly targeted? (Rempel et al. 2024)
  2. Orbicella annularis corals are an endangered species that are commonly targeted by parrotfishes. How frequently do these corals heal from parrotfish bites and what factors influence recovery rates? (Rempel et al. 2020) ​
  3. What are the feeding preferences of different parrotfish species for certain corals and sponges? (Burkepile et al. 2019)

​The roles of parrotfishes as detritus feeders

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Parrotfishes and surgeonfishes are important herbivores on Caribbean reefs, but did you know that they also consume fish feces? This behavior – also seen in dogs, moose, and many other animals – is called coprophagy and can be important for their nutrition!
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Research led by former master's student Hannah Rempel and undergraduate Abigail Siebert documented species-specific levels of coprophagy by a wide range of Caribbean parrotfishes and surgeonfishes. They found that they predominantly feed upon the feces of an abundant planktivore, the Brown Chromis, and that these feces may be an important (yet previously understudied) source of nutrients! (Rempel, Siebert et al. 2022)

The roles of parrotfishes as algae grazers and total grazing impacts

Our lab group collaborated with the Burkepile Lab at UCSB to help address questions such as:
  • What is the total grazing impact of parrotfishes? (Ruttenberg et al. 2019);
  • ​What are the mechanics of parrotfish grazing? (Adam et al. 2018);
  • What are the species-specific foraging preferences of parrotfishes for algae? (Adam et al. 2015B);
  • What do we know – and don't know – about the importance of parrotfish grazing for reefs? (Adam et al. 2015A).  

Data Availability

​Data from these studies are publically available through NOAA's National Centers for Environmental Information:
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