About

John F Bruno is a marine ecologist and Distinguished Professor in the Department of Biology at The University of North Carolina at Chapel Hill. His research focuses on marine biodiversity and macroecology, coral reef ecology and conservation, and the impacts of climate change on marine ecosystems. He earned his Ph.D. from Brown University in Ecology and Evolutionary Biology and completed a postdoctoral fellowship at Cornell University specializing in disease ecology. Bruno's lab primarily conducts research in the Galápagos and the Caribbean, including Belize and the Cayman Islands. He actively communicates his work through various platforms, including a recent piece in the Sunday Review section of the New York Times discussing fieldwork and climate change impacts on coral reefs, an op-ed in the Washington Post on coral reef conservation, and a multimedia piece about his team's work in the Galápagos.

Research topics

• Biology
• Ecology
• Geography
• Environmental science
• Fishery
• Oceanography
• Geology

Selected publications

• Using DNA Metabarcoding of Cloacal Swabs to Elucidate the Diets of Four Coastal Shark Species

  UNC Libraries · 2026-04-02

  articleOpen access1st authorCorresponding

  The Atlantic sharpnose (Rhizoprionodon terraenovae), blacknose (Carcharhinus acronotus), blacktip (Carcharhinus limbatus), and bonnethead (Sphyrna tiburo) sharks are commonly encountered large mobile consumers found in the estuaries along the western North Atlantic coast. The bulk of the dietary data for these species has been coarsely recorded at a broad taxonomic level (e.g., “teleost fish”). Here, we used DNA metabarcoding of fecal DNA collected using non-lethal cloacal swabs to identify the species of prey contributing to the diets of these shark species and measure the degree of trophic overlap. Samples were collected from 24 Atlantic sharpnose, 33 blacknose, six blacktip, and 17 bonnethead sharks in the summer of 2020. Based on previous dietary research on these shark species, we targeted teleost fishes and crustaceans using two previously published primer sets. From the 80 sharks sampled off the coast of North Carolina, we identified 38 prey taxa, with 82% classified to the species level and all assigned to at least the genus and family levels. The most common prey taxa found in the diet of the bonnethead was Atlantic blue crab (Callinectes sapidus; 44.75%, based on percent of occurrence) followed by penaeid shrimp (Penaeus spp.; 24.41%), mantis shrimp (Squilla empusa; 20.34%), and spot (Leiostomus xanthurus; 4.75%). Atlantic sharpnose and blacknose sharks had the largest Levin’s niche overlap, with both species relying on the same two most frequently consumed prey taxa: penaeid shrimp (Atlantic sharpnose: 33.33%, percent of occurrence, and blacknose: 34.78%) and spot (Atlantic sharpnose: 32.70% and blacknose: 22.32%). Bonnetheads and blacktips had the least amount of overlap between all shark species, where blacktips primarily consumed menhaden (Brevoortia spp.; 58.62%) and penaeid shrimp (26.44%). Our findings highlight the value of DNA metabarcoding in refining our understanding of predator diets, moving beyond broad taxonomic classifications to identify species-level prey associations and trophic interactions. As coastal habitats undergo increasing alteration due to anthropogenic impacts, such information is crucial for fisheries management, helping to identify key prey dependencies and anticipate potential ecosystem shifts.

  PublisherDOI

• Using DNA Metabarcoding of Cloacal Swabs to Elucidate the Diets of Four Coastal Shark Species

  Wild · 2026-03-09 · 1 citations

  articleOpen accessSenior author

  The Atlantic sharpnose (Rhizoprionodon terraenovae), blacknose (Carcharhinus acronotus), blacktip (Carcharhinus limbatus), and bonnethead (Sphyrna tiburo) sharks are commonly encountered large mobile consumers found in the estuaries along the western North Atlantic coast. The bulk of the dietary data for these species has been coarsely recorded at a broad taxonomic level (e.g., “teleost fish”). Here, we used DNA metabarcoding of fecal DNA collected using non-lethal cloacal swabs to identify the species of prey contributing to the diets of these shark species and measure the degree of trophic overlap. Samples were collected from 24 Atlantic sharpnose, 33 blacknose, six blacktip, and 17 bonnethead sharks in the summer of 2020. Based on previous dietary research on these shark species, we targeted teleost fishes and crustaceans using two previously published primer sets. From the 80 sharks sampled off the coast of North Carolina, we identified 38 prey taxa, with 82% classified to the species level and all assigned to at least the genus and family levels. The most common prey taxa found in the diet of the bonnethead was Atlantic blue crab (Callinectes sapidus; 44.75%, based on percent of occurrence) followed by penaeid shrimp (Penaeus spp.; 24.41%), mantis shrimp (Squilla empusa; 20.34%), and spot (Leiostomus xanthurus; 4.75%). Atlantic sharpnose and blacknose sharks had the largest Levin’s niche overlap, with both species relying on the same two most frequently consumed prey taxa: penaeid shrimp (Atlantic sharpnose: 33.33%, percent of occurrence, and blacknose: 34.78%) and spot (Atlantic sharpnose: 32.70% and blacknose: 22.32%). Bonnetheads and blacktips had the least amount of overlap between all shark species, where blacktips primarily consumed menhaden (Brevoortia spp.; 58.62%) and penaeid shrimp (26.44%). Our findings highlight the value of DNA metabarcoding in refining our understanding of predator diets, moving beyond broad taxonomic classifications to identify species-level prey associations and trophic interactions. As coastal habitats undergo increasing alteration due to anthropogenic impacts, such information is crucial for fisheries management, helping to identify key prey dependencies and anticipate potential ecosystem shifts.

  PublisherOA PDFDOI

• Ocean weather, biological rates, and unexplained global ecological patterns

  UNC Libraries · 2025-01-14

  articleOpen access

  As on land, oceans exhibit high temporal and spatial temperature variation. This "ocean weather" contributes to the physiological and ecological processes that ultimately determine the patterns of species distribution and abundance, yet is often unrecognized, especially in tropical oceans. Here, we tested the paradigm of temperature stability in shallow waters (<12.5 m) across different zones of latitude. We collated hundreds of in situ, high temporal-frequency ocean temperature time series globally to produce an intuitive measure of temperature variability, ranging in scale from quarter-diurnal to annual time spans. To estimate organismal sensitivity of ectotherms (i.e. microbes, algae, and animals whose body temperatures depend upon ocean temperature), we computed the corresponding range of biological rates (such as metabolic rate or photosynthesis) for each time span, assuming an exponential relationship. We found that subtropical regions had the broadest temperature ranges at time spans equal to or shorter than a month, while temperate and tropical systems both exhibited narrow (i.e. stable) short-term temperature range estimates. However, temperature-dependent biological rates in tropical regions displayed greater ranges than in temperate systems. Hence, our results suggest that tropical ectotherms may be relatively more sensitive to short-term thermal variability. We also highlight previously unexplained macroecological patterns that may be underpinned by short-term temperature variability.

  PublisherDOI

• Temperature determines physiological rates and predation in Galápagos rocky reefs

  Marine Ecology Progress Series · 2025-07-03 · 1 citations

  articleSenior author

  Water temperature plays a critical role in determining physiological rates in marine ectotherms and influences the strength of ecological interactions. We investigated the effects of temperature on multiple traits of the whelk Hexaplex princep s —a common predator in the rocky reefs of the Galápagos, a region characterized by significant temperature fluctuations. We measured metabolic rate, activity levels, prey handling time, and feeding rates across a temperature gradient. First, we conducted respirometry assays to measure the temperature dependence of metabolism. Next, we performed mesocosm experiments to assess how temperature affects predator activity, prey handling time, and feeding rates. Third, we conducted a field experiment to measure predation’s response to seasonal temperature changes. The results from our mesocosms experiment showed a large variation in thermal performance across traits. Nevertheless, all traits exhibit low performance at our coldest experimental temperature with a peak at intermediate temperature, suggesting a unimodal response. Similarly, we observed higher feeding rates in the field at medium temperatures. Our results highlight the importance of temperature in moderating physiological rates and interactions between species, and the challenges of predicting complex ecological processes from individual traits (e.g. metabolic rate, movement, prey handling time). As ocean temperatures continue to rise, understanding how temperature shapes physiological responses across organisms is essential for predicting the future dynamics of marine communities.

  PublisherDOI

• Considerations for determining warm-water coral reef tipping points

  Earth System Dynamics · 2025-02-07 · 6 citations

  articleOpen access

  Abstract. Warm-water coral reefs are facing unprecedented human-driven threats to their continued existence as biodiverse functional ecosystems upon which hundreds of millions of people rely. These impacts may drive coral ecosystems past critical thresholds, beyond which the system reorganises, often abruptly and potentially irreversibly; this is what the Intergovernmental Panel on Climate Change (IPCC, 2022) define as a tipping point. Determining tipping point thresholds for coral reef ecosystems requires a robust assessment of multiple stressors and their interactive effects. In this perspective piece, we draw upon the recent global tipping point revision initiative (Lenton et al., 2023a) and a literature search to identify and summarise the diverse range of interacting stressors that need to be considered for determining tipping point thresholds for warm-water coral reef ecosystems. Considering observed and projected stressor impacts, we endorse the global tipping point revision's conclusion of a global mean surface temperature (relative to pre-industrial) tipping point threshold of 1.2 °C (range 1–1.5 °C) and the long-term impacts of atmospheric CO2 concentrations above 350 ppm, while acknowledging that comprehensive assessment of stressors, including ocean warming response dynamics, overshoot, and cascading impacts, have yet to be sufficiently realised. These tipping point thresholds have already been exceeded, and therefore these systems are in an overshoot state and are reliant on policy actions to bring stressor levels back within tipping point limits. A fuller assessment of interacting stressors is likely to further lower the tipping point thresholds in most cases. Uncertainties around tipping points for such crucially important ecosystems underline the imperative of robust assessment and, in the case of knowledge gaps, employing a precautionary principle favouring lower-range tipping point values.

  PublisherOA PDFDOI

• Predator response diversity to warming enables ecosystem resilience in the Galápagos

  2025-05-29

  preprintOpen accessSenior author

  An important impact of global warming in nature is the decline of ecological functions such as primary production, habitat provision, and carbon sequestration. These functions can be disrupted when the species that perform them are impaired by anthropogenic warming or other stressors. Where there is a diversity of responses to warming among the species filling these roles, the function is more likely to be maintained despite the loss of the least tolerant species. However, the response diversity to warming of key functions is generally unknown, particularly for the roles played by predatory and marine species. Here we show that the thermal sensitivity of predation to acute warming varies substantially among four marine invertebrate carnivores: three whelks and a sea star that inhabit rocky reefs around the Galápagos islands. Two of the four predators were clearly adapted to cooler temperatures and their functional performance declined dramatically with experimental warming. In contrast, predation by two whelks, and one in particular, improved with warming, including beyond temperatures expected in 2100 under the most pessimistic emissions scenario. These results suggest that a high level of temperature response diversity of predation could help maintain this critical function in a variable and changing environment.

  PublisherOA PDFDOI

• Impacts of Climate Change on Marine Foundation Species

  UNC Libraries · 2025-01-14

  articleOpen access

  Marine foundation species are the biotic basis for many of the world's coastal ecosystems, providing structural habitat, food, and protection for myriad plants and animals as well as many ecosystem services. However, climate change poses a significant threat to foundation species and the ecosystems they support. We review the impacts of climate change on common marine foundation species, including corals, kelps, seagrasses, salt marsh plants, mangroves, and bivalves. It is evident that marine foundation species have already been severely impacted by several climate change drivers, often through interactive effects with other human stressors, such as pollution, overfishing, and coastal development. Despite considerable variation in geographical, environmental, and ecological contexts, direct and indirect effects of gradual warming and subsequent heatwaves have emerged as the most pervasive drivers of observed impact and potent threat across all marine foundation species, but effects from sea level rise, ocean acidification, and increased storminess are expected to increase. Documented impacts include changes in the genetic structures, physiology, abundance, and distribution of the foundation species themselves and changes to their interactions with other species, with flow-on effects to associated communities, biodiversity, and ecosystem functioning. We discuss strategies to support marine foundation species into the Anthropocene, in order to increase their resilience and ensure the persistence of the ecosystem services they provide.

  PublisherDOI

• Smooth and Spiky: The Importance of Variability in Marine Climate Change Ecology

  UNC Libraries · 2025-01-15

  articleOpen access

  Greenhouse gas emissions are warming the ocean with profound consequences at all levels of organization, from organismal rates to ecosystem processes. The proximate driver is an interplay between anthropogenic warming (the trend) and natural fluctuations in local temperature. These two properties cause anomalously warm events such as marine heatwaves to occur with increasing frequency and magnitude. Because warming and variance are not uniform, there is a large degree of geographic variation in temporal temperature variability. We review the underappreciated interaction between trend and variance in the ocean and how it modulates ecological responses to ocean warming. For example, organisms in more thermally variable environments are often more acclimatized and/or adapted to temperature extremes and are thus less sensitive to anthropogenic heatwaves. Considering both trend and variability highlights the importance of processes like legacy effects and extinction debt that influence the rate of community transformation.

  PublisherDOI

• Publisher Correction: Climate change threatens the world’s marine protected areas

  UNC Libraries · 2025-01-15

  articleOpen access1st authorCorresponding
  PublisherDOI

• Corrigendum: Top-down and bottom-up control in the Galápagos Upwelling System

  UNC Libraries · 2025-01-15

  erratumOpen access

  Corrigendum for "Top-down and bottom-up control in the Galápagos Upwelling System"

  PublisherDOI

Recent grants

• Cascading effects of predator diversity in a marine food web

  NSF · $350k · 2006–2009

• Collaborative research: Biodiversity and ecosystem functioning in plant-grazer systems: experimental tests in a marine benthic community

  NSF · $294k · 2003–2006

• Collaborative Research: Origins and Spread of the Aspergillus-Gorgonian Coral Epizootic: Role of Climate and Environmental Facilitators

  NSF · $260k · 2003–2008

• RAPID: Lionfish invasion of the Mesoamerican reef: community invasibility and the evolutionary response of prey avoidance behavior to a novel predator

  NSF · $133k · 2009–2010

• Temperature Regulation of Top-Down Control in a Pacific Upwelling System

  NSF · $944k · 2022–2025

Frequent coauthors

• Elizabeth R. Selig

  124 shared

• Benjamin S. Halpern

  University of California, Santa Barbara

  117 shared

• Carrie V. Kappel

  National Center for Ecological Analysis and Synthesis

  112 shared

• Dennis Heinemann

  Marine Mammal Commission

  105 shared

• Mark Spalding

  University of Cambridge

  105 shared

• Rod Fujita

  Environmental Defense Fund

  105 shared

• Kenneth S. Casey

  NOAA National Centers for Environmental Information

  104 shared

• Helen Fox

  Coral Reef Alliance

  101 shared

Education

• PhD

  Brown University

  2000