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Dunn RE, Benkwitt CE, Maury O, Barrier N, Carr P, Graham NAJ. Island restoration to rebuild seabird populations and amplify coral reef functioning. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2024:e14313. [PMID: 38887868 DOI: 10.1111/cobi.14313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 03/19/2024] [Accepted: 04/15/2024] [Indexed: 06/20/2024]
Abstract
Mobile organisms like seabirds can provide important nutrient flows between ecosystems, but this connectivity has been interrupted by the degradation of island ecosystems. Island restoration (via invasive species eradications and the restoration of native vegetation) can reestablish seabird populations and their nutrient transfers between their foraging areas, breeding colonies, and adjacent nearshore habitats. Its diverse benefits are making island restoration increasingly common and scalable to larger islands and whole archipelagos. We identified the factors that influence breeding seabird abundances throughout the Chagos Archipelago in the Indian Ocean and conducted predictive modeling to estimate the abundances of seabirds that the archipelago could support under invasive predator eradication and native vegetation restoration scenarios. We explored whether the prey base exists to support restored seabird populations across the archipelago, calculated the nitrogen that restored populations of seabirds might produce via their guano, and modeled the cascading conservation gains that island restoration could provide. Restoration was predicted to increase breeding pairs of seabirds to over 280,000, and prey was predicted to be ample to support the revived seabird populations. Restored nutrient fluxes were predicted to result in increases in coral growth rates, reef fish biomasses, and parrotfish grazing and bioerosion rates. Given these potential cross-ecosystem benefits, our results support island restoration as a conservation priority that could enhance resilience to climatic change effects, such as sea-level rise and coral bleaching. We encourage the incorporation of our estimates of cross-ecosystem benefits in prioritization exercises for island restoration.
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Affiliation(s)
- Ruth E Dunn
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
- The Lyell Centre, Heriot-Watt University, Edinburgh, UK
| | | | - Olivier Maury
- Institut de Recherche pour le Développement, Université de Montpellier, Sète, France
| | - Nicolas Barrier
- Institut de Recherche pour le Développement, Université de Montpellier, Sète, France
| | - Peter Carr
- Institute of Zoology, Zoological Society of London, London, UK
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Benkwitt CE, D'Angelo C, Dunn RE, Gunn RL, Healing S, Mardones ML, Wiedenmann J, Wilson SK, Graham NAJ. Seabirds boost coral reef resilience. SCIENCE ADVANCES 2023; 9:eadj0390. [PMID: 38055814 DOI: 10.1126/sciadv.adj0390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 11/03/2023] [Indexed: 12/08/2023]
Abstract
Global climate change threatens tropical coral reefs, yet local management can influence resilience. While increasing anthropogenic nutrients reduce coral resistance and recovery, it is unknown how the loss, or restoration, of natural nutrient flows affects reef recovery. Here, we test how natural seabird-derived nutrient subsidies, which are threatened by invasive rats, influence the mechanisms and patterns of reef recovery following an extreme marine heatwave using multiyear field experiments, repeated surveys, and Bayesian modeling. Corals transplanted from rat to seabird islands quickly assimilated seabird-derived nutrients, fully acclimating to new nutrient conditions within 3 years. Increased seabird-derived nutrients, in turn, caused a doubling of coral growth rates both within individuals and across entire reefs. Seabirds were also associated with faster recovery time of Acropora coral cover (<4 years) and more dynamic recovery trajectories of entire benthic communities. We conclude that restoring seabird populations and associated nutrient pathways may foster greater coral reef resilience through enhanced growth and recovery rates of corals.
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Affiliation(s)
| | - Cecilia D'Angelo
- Coral Reef Laboratory, School of Ocean and Earth Science, University of Southampton, Southampton SO143ZH, UK
| | - Ruth E Dunn
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
- The Lyell Centre, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Rachel L Gunn
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
- Animal Evolutionary Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf Der Morgenstelle 28, 72076 Tübingen, Germany
| | - Samuel Healing
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - M Loreto Mardones
- Coral Reef Laboratory, School of Ocean and Earth Science, University of Southampton, Southampton SO143ZH, UK
| | - Joerg Wiedenmann
- Coral Reef Laboratory, School of Ocean and Earth Science, University of Southampton, Southampton SO143ZH, UK
| | - Shaun K Wilson
- Australian Institute of Marine Science, Indian Ocean Marine Research Centre, Crawley, WA 6009, Australia
- University of Western Australia, UWA Oceans Institute, Crawley, WA 6009, Australia
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Trevail AM, Nicoll MAC, Freeman R, Le Corre M, Schwarz J, Jaeger A, Bretagnolle V, Calabrese L, Feare C, Lebarbenchon C, Norris K, Orlowski S, Pinet P, Plot V, Rocamora G, Shah N, Votier SC. Tracking seabird migration in the tropical Indian Ocean reveals basin-scale conservation need. Curr Biol 2023; 33:5247-5256.e4. [PMID: 37972589 DOI: 10.1016/j.cub.2023.10.060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 09/20/2023] [Accepted: 10/26/2023] [Indexed: 11/19/2023]
Abstract
Understanding marine predator distributions is an essential component of arresting their catastrophic declines.1,2,3,4 In temperate, polar, and upwelling seas, predictable oceanographic features can aggregate migratory predators, which benefit from site-based protection.5,6,7,8 In more oligotrophic tropical waters, however, it is unclear whether environmental conditions create similar multi-species hotspots. We track the non-breeding movements and habitat preferences of a tropical seabird assemblage (n = 348 individuals, 9 species, and 10 colonies in the western Indian Ocean), which supports globally important biodiversity.9,10,11,12 We mapped species richness from tracked populations and then predicted the same diversity measure for all known Indian Ocean colonies. Most species had large non-breeding ranges, low or variable residency patterns, and specific habitat preferences. This in turn revealed that maximum species richness covered >3.9 million km2, with no focused aggregations, in stark contrast to large-scale tracking studies in all other ocean basins.5,6,7,13,14 High species richness was captured by existing marine protected areas (MPAs) in the region; however, most occurred in the unprotected high seas beyond national jurisdictions. Seabirds experience cumulative anthropogenic impacts13 and high mortality15,16 during non-breeding. Therefore, our results suggest that seabird conservation in the tropical Indian Ocean requires an ocean-wide perspective, including high seas legislation.17 As restoration actions improve the outlook for tropical seabirds on land18,19,20,21,22 and environmental change reshapes the habitats that support them at sea,15,16 appropriate marine conservation will be crucial for their long-term recovery and whole ecosystem restoration.
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Affiliation(s)
- Alice M Trevail
- Environment and Sustainability Institute, University of Exeter, Penryn TR10 9FE, UK.
| | - Malcolm A C Nicoll
- Institute of Zoology, Zoological Society of London, Regent's Park, London NW14RY, UK
| | - Robin Freeman
- Institute of Zoology, Zoological Society of London, Regent's Park, London NW14RY, UK
| | - Matthieu Le Corre
- Écologie marine tropicale des océans Pacifique et Indien, UMR ENTROPIE, Université de la Réunion, 15 Avenue René Cassin, BP 7151, 97715 Saint Denis, La Réunion, France
| | - Jill Schwarz
- School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK
| | - Audrey Jaeger
- Écologie marine tropicale des océans Pacifique et Indien, UMR ENTROPIE, Université de la Réunion, 15 Avenue René Cassin, BP 7151, 97715 Saint Denis, La Réunion, France
| | - Vincent Bretagnolle
- Centre d'Etudes Biologiques de Chizé (CEBC-CNRS), 79360 Beauvoir sur Niort, France
| | - Licia Calabrese
- Centre d'Etudes Biologiques de Chizé (CEBC-CNRS), 79360 Beauvoir sur Niort, France; Island Conservation Society, Pointe Larue, Mahé P.O Box 775, Seychelles; Island Biodiversity and Conservation Centre of the University of Seychelles, Anse Royale, Mahé, Seychelles
| | - Chris Feare
- WildWings Bird Management, 2 North View Cottages, Grayswood Common, Haslemere, Surrey GU27 2DN, UK; School of Biological, Earth and Environmental Sciences, Faculty of Science, University of New South Wales (UNSW), NSW, Sydney 2052, Australia
| | - Camille Lebarbenchon
- Université de la Réunion, UMR Processus Infectieux en Milieu Insulaire Tropical (PIMIT), INSERM 1187, CNRS 9192, IRD 249, Saint Denis, La Réunion, France
| | - Ken Norris
- Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Sabine Orlowski
- Écologie marine tropicale des océans Pacifique et Indien, UMR ENTROPIE, Université de la Réunion, 15 Avenue René Cassin, BP 7151, 97715 Saint Denis, La Réunion, France
| | - Patrick Pinet
- Parc national de La Réunion, Life+ Pétrels. 258 Rue de la République, 97431 Plaine des Palmistes, La Réunion, France
| | - Virginie Plot
- Écologie marine tropicale des océans Pacifique et Indien, UMR ENTROPIE, Université de la Réunion, 15 Avenue René Cassin, BP 7151, 97715 Saint Denis, La Réunion, France
| | - Gerard Rocamora
- Centre d'Etudes Biologiques de Chizé (CEBC-CNRS), 79360 Beauvoir sur Niort, France; Island Biodiversity and Conservation Centre of the University of Seychelles, Anse Royale, Mahé, Seychelles
| | - Nirmal Shah
- Nature Seychelles, P.O. Box 1310, The Centre for Environment and Education, Roche Caiman, Mahé, Seychelles; The Centre for Environment and Education, Roche Caiman, Mahé, Seychelles
| | - Stephen C Votier
- The Lyell Centre, Heriot-Watt University, Edinburgh EH14 4AS, UK.
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Benkwitt CE, Gunn RL, Le Corre M, Carr P, Graham NAJ. Rat eradication restores nutrient subsidies from seabirds across terrestrial and marine ecosystems. Curr Biol 2021; 31:2704-2711.e4. [PMID: 33887185 DOI: 10.1016/j.cub.2021.03.104] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/04/2021] [Accepted: 03/31/2021] [Indexed: 12/21/2022]
Abstract
Biological invasions pose a threat to nearly every ecosystem worldwide.1,2 Although eradication programs can successfully eliminate invasive species and enhance native biodiversity, especially on islands,3 the effects of eradication on cross-ecosystem processes are unknown. On islands where rats were never introduced, seabirds transfer nutrients from pelagic to terrestrial and nearshore marine habitats, which in turn enhance the productivity, biomass, and functioning of recipient ecosystems.4-6 Here, we test whether rat eradication restores seabird populations, their nutrient subsidies, and some of their associated benefits for ecosystem function to tropical islands and adjacent coral reefs. By comparing islands with different rat invasion histories, we found a clear hierarchy whereby seabird biomass, seabird-driven nitrogen inputs, and the incorporation of seabird-derived nutrients into terrestrial and marine food chains were highest on islands where rats were never introduced, intermediate on islands where rats were eradicated 4-16 years earlier, and lowest on islands with invasive rats still present. Seabird-derived nutrients diminished from land to sea and with increasing distance to rat-eradicated islands, but extended at least 300 m from shore. Although rat eradication enhanced seabird-derived nutrients in soil, leaves, marine algae, and herbivorous reef fish, reef fish growth was similar around rat-eradicated and rat-infested islands. Given that the loss of nutrient subsidies is of global concern,7 that removal of invasive species restores previously lost nutrient pathways over relatively short timescales is promising. However, the full return of cross-ecosystem nutrient subsidies and all of their associated demographic benefits may take multiple decades.
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Affiliation(s)
| | - Rachel L Gunn
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Matthieu Le Corre
- UMR ENTROPIE, Université de La Réunion, IRD, CNRS, IFREMER, Université de Nouvelle-Calédonie, Avenue René Cassin, 97490 Sainte Clotilde, La Réunion
| | - Peter Carr
- Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK; Environment and Sustainability Institute, University of Exeter, Penryn Campus, Cornwall TR10 9EZ, UK
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Burkepile DE. Ecology: E-rat-ication to restore reefs. Curr Biol 2021; 31:R786-R788. [PMID: 34157261 DOI: 10.1016/j.cub.2021.04.069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Invasive species often drive native species to local extinction. A new study shows that removing invasive rats from tropical islands fosters recovery of native seabirds. Rising seabird populations reestablish key cross-ecosystem nutrient subsidies, reconnecting oceanic, island, and coral reef ecosystems.
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Affiliation(s)
- Deron E Burkepile
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA; Marine Science Institute, University of California, Santa Barbara, CA 93106, USA.
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