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Carlson RR, Crowder LB, Martin RE, Asner GP. The effect of reef morphology on coral recruitment at multiple spatial scales. Proc Natl Acad Sci U S A 2024; 121:e2311661121. [PMID: 38190515 PMCID: PMC10823213 DOI: 10.1073/pnas.2311661121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 11/24/2023] [Indexed: 01/10/2024] Open
Abstract
Coral reefs are in decline worldwide, making it increasingly important to promote coral recruitment in new or degraded habitat. Coral reef morphology-the structural form of reef substrate-affects many aspects of reef function, yet the effect of reef morphology on coral recruitment is not well understood. We used structure-from-motion photogrammetry and airborne remote sensing to measure reef morphology (rugosity, curvature, slope, and fractal dimension) across a broad continuum of spatial scales and evaluated the effect of morphology on coral recruitment in three broadcast-spawning genera. We also measured the effect of other environmental and biotic factors such as fish density, adult coral cover, hydrodynamic larval import, and depth on coral recruitment. All variables combined explained 72% of coral recruitment in the study region. Coarse reef rugosity and curvature mapped at ≥2 m spatial resolution-such as large colonies, knolls, and boulders-were positively correlated with coral recruitment, explaining 22% of variation in recruitment. Morphology mapped at finer scales (≤32 cm resolution) was not significant. Hydrodynamic larval import was also positively related to coral recruitment in Porites and Montipora spp., and grazer fish density was linked to significantly lower recruitment in all genera. In addition, grazer density, reef morphology, and hydrodynamic import had differential effects on coral genera, reflecting genus-specific life history traits, and model performance was lower in gonochoric species. Overall, coral reef morphology is a key indicator of recruitment potential that can be detected by remote sensing, allowing potential larval sinks to be identified and factored into restoration actions.
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Affiliation(s)
- Rachel R. Carlson
- Emmett Interdisciplinary Program in Environment and Resources, Doerr School of Sustainability, Stanford University, Stanford, CA94305
- Center for Global Discovery and Conservation Science, Arizona State University, Hilo, HI96720
| | - Larry B. Crowder
- Emmett Interdisciplinary Program in Environment and Resources, Doerr School of Sustainability, Stanford University, Stanford, CA94305
| | - Roberta E. Martin
- Center for Global Discovery and Conservation Science, Arizona State University, Hilo, HI96720
| | - Gregory P. Asner
- Center for Global Discovery and Conservation Science, Arizona State University, Hilo, HI96720
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McDevitt-Irwin JM, McCauley DJ, Brumbaugh DR, Elmer F, Ferretti F, White TD, Wible JG, Micheli F. Dynamic interplay: disentangling the temporal variability of fish effects on coral recruitment. Sci Rep 2023; 13:20971. [PMID: 38017077 PMCID: PMC10684556 DOI: 10.1038/s41598-023-47758-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 11/17/2023] [Indexed: 11/30/2023] Open
Abstract
Ecosystems around the world are continuously undergoing recovery from anthropogenic disturbances like climate change, overexploitation, and habitat destruction. Coral reefs are a prime example of a threatened ecosystem and coral recruitment is a critical component of reef recovery from disturbances. Reef fishes structure this recruitment by directly consuming macroalgae and coral recruits or by indirectly altering the substrate to facilitate coral settlement (e.g., grazing scars). However, how these direct and indirect mechanisms vary through time remains largely unknown. Here, we quantified coral recruitment on settlement tiles with divots that mimic grazing scars and caging treatments to exclude or allow fish feeding over 3 years at Palmyra Atoll in the Pacific Ocean. We found that the positive and negative effects of fishes on coral recruitment varies through time. After 3 years, both grazing scars and fish grazing no longer predicted coral recruitment, suggesting that the role of fishes decreases over time. Our results emphasize that reef fish populations are important in promoting initial coral recovery after disturbances. However, over time, factors like the environment may become more important. Future work should continue to explore how the strength and direction of top-down control by consumers varies through time across multiple ecosystems.
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Affiliation(s)
- Jamie M McDevitt-Irwin
- Hopkins Marine Station, Stanford University, Pacific Grove, CA, USA.
- Marine Science Institute, University of California, Santa Barbara, CA, USA.
| | - Douglas J McCauley
- Marine Science Institute, University of California, Santa Barbara, CA, USA
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA, USA
| | - Daniel R Brumbaugh
- Elkhorn Slough National Estuarine Research Reserve, Watsonville, CA, USA
- Environmental Studies, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Franziska Elmer
- School for Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
- Center for Marine Resource Studies, School for Field Studies, Cockburn Harbour, South Caicos, Turks and Caicos Islands
| | - Francesco Ferretti
- Fish and Wildlife Conservation Department, Virginia Tech, Blacksburg, VA, USA
| | - Timothy D White
- Hopkins Marine Station, Stanford University, Pacific Grove, CA, USA
| | - Joseph G Wible
- Hopkins Marine Station, Stanford University, Pacific Grove, CA, USA
| | - Fiorenza Micheli
- Hopkins Marine Station, Stanford University, Pacific Grove, CA, USA
- Center for Ocean Solutions, Stanford University, Pacific Grove, CA, USA
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