Coral reefs, which are among the most biodiverse ecosystems on the planet, are declining at an alarming rate. To counteract the threats posed by climate change and other anthropogenic impacts, conservation efforts such as active coral reef restoration have increased globally. Ecological restoration aims to assist natural recovery and increase coral reefs resilience in an effort to preserve the many functions and services these iconic ecosystems provide to society. Under current climate scenarios, coastal and island populations are the first to suffer from continued ecosystem degradation. For example, the Maldives’ vulnerability to global and local coral reef threats is evident for a nation that lives on shallow reef islands with an economy driven by fisheries and tourism. However, little information is available on suitable, regionally tested coral restoration techniques that could be applied at an ecological meaningful scale in the Maldives. ‘Coral gardening’, which comprises fragment farming in coral nurseries followed by the transplantation of these corals to a restoration site, appears particularly suitable for remote locations like the Maldives. The method can be applied by local communities or tourism stakeholders to assist local reef recovery, while creating awareness, stewardship and even income opportunities. This research assesses the application of ‘coral gardening’ for upscaled coral restoration efforts in the Maldives, providing the necessary regional validation and useful insights into the various aspects of this technique for the first time. To evaluate the suitability and performance of this restoration approach across different regions and farming habitats (i.e., lagoon and reef), a total of six mid-water coral rope nurseries were assessed on the local island of Magoodhoo in Faafu Atoll and on Athuruga resort island in Alif Dhaal Atoll. Coral gardening success was examined for three different coral genera, namely Acropora, Pocillopora and Porites, using a common monitoring protocol. This delivered regional benchmarks for fragment growth over time and at different depths as well as coral survival, which typically exceeded 90% in both farming habitats. In addition, ecological interactions were investigated by including mutualistic fauna and predator associations in the assessments of farmed and transplanted corals. For example, a positive correlation between Trapezia guard crabs and farming stock health was observed, while the corallivorous nudibranch Phestilla is newly reported on coral nursery stock. Coral restoration demand and success is further reviewed in the context of natural reef recovery on the restoration site as well as potential ecological implications of restoration activities. Here, coral outplanting was successful and significantly benefitted the degraded reef environment, increasing fish abundance and diversity along with natural coral cover While the overall study results are encouraging, this research also addresses potential risks to coral restoration success, in particular the negative effects of prolonged monitoring and maintenance disruptions and the impacts of coral disease occurrence. Using a number of real case studies, it is demonstrated how these factors can diminish coral gardening outcomes and project success, if not managed in time. Overall, the findings presented and the practical applications concluded from this work hope to provide a scientific baseline for future restoration efforts that can guides restoration practitioners towards efficient conservation work.

Le scogliere coralline, conosciute per essere uno degli ecosistemi più ricchi di biodiversità del pianeta, stanno diminuendo ad un ritmo allarmante. Per contrastare le minacce poste dai cambiamenti climatici e da altri impatti di origine antropica gli sforzi di conservazione attiva, come il ripristino della scogliera corallina, sono aumentati a livello globale. Il ripristino ecologico si pone come obiettivo principale quello di assistere il recupero naturale, aumentandone la resilienza, delle scogliere coralline nel tentativo di preservare le numerose funzioni e servizi ecosistemici che questi habitat iconici forniscono alla società. La vulnerabilità delle Maldive alle minacce globali e locali è più evidente in quanto rappresentata da isole coralline con un'economia basata sulle attività come la pesca e il turismo. Tuttavia, sono disponibili poche informazioni sulle tecniche migliori di ripristino dei coralli che potrebbero essere applicate a livello regionale alle Maldive. Il "Coral Gardening", una tecnica che comprende l'allevamento di frammenti di coralli in vivai sommersi seguito dal trapianto di quest’ultimi in un sito di restauro, sembra particolarmente adatta per una località remota come l’arcipelago maldiviano. Il metodo, infatti, può essere utilizzato dalle comunità locali o organizzazioni turistiche per accelerare il recupero locale della scogliera corallina, creando al contempo consapevolezza e permettendo una gestione mirata delle sue risorse. Questo studio valuta l'applicazione su larga scala del "Coral Gardening" per il ripristino dei coralli alle Maldive, fornendo per la prima volta la necessaria validazione a livello regionale di questa tecnica. Per stimare le prestazioni di questo approccio di ripristino in diverse regioni e habitat (ad es. laguna e scogliera corallina), sono stati valutati un totale di sei vivai sommersi di corallo presenti sia sull'isola locale di Magoodhoo nell'atollo di Faafu che sull'isola turistica di Athuruga nell'atollo di Alif Dhaal. Il prestazioni della tecnica del coral gardening è stato valutato per tre diversi generi di coralli, quali Acropora, Pocillopora e Porites, utilizzando un protocollo di monitoraggio standard. Tale analisi hanno fornito parametri di riferimento regionali per la crescita dei frammenti in funzione del tempo e della profondità, nonché in funzione dei tassi di sopravvivenza dei coralli, che in genere superavano abbondantemente il 90% in entrambi gli habitat utilizzati. Inoltre, sono state prese in considerazione le interazioni ecologiche quali la fauna associata ai coralli e la presenza di predatori nel confronto tra i coralli allevati e trapiantati. L’utilizzo e l’efficacia delle tecniche di ripristino dei coralli sono state ulteriormente riesaminate rispetto al recupero naturale della scogliera corallina nel sito di ripopolamento, nonché delle potenziali implicazioni ecologiche delle attività di ripristino eseguite. In questo caso, il trapianto di coralli ha fornito ottimi risultati e ha apportato benefici significativi all'ambiente degradato della scogliera corallina, attraverso l’aumento in termini di abbondanza e diversità della comunità ittica, così come della copertura naturale dei coralli. Sebbene i risultati complessivi dello studio siano incoraggianti, questa ricerca affronta anche potenziali rischi per il successo del ripristino delle scogliere coralline. In particolare sono stati valutati i rischi inerenti gli effetti negativi legati ad un’interruzione prolungata delle attività di monitoraggio e manutenzione e degli eventuali impatti di patologie in grado di colpire i coralli. Nel complesso, i risultati presentati e le implicazioni pratiche ottenute grazie a questo lavoro forniranno una base scientifica per i futuri studi riguardanti il restauro delle scogliere coralline con la speranza che possano rappresentare una guida verso una conservazione di questo habitat più efficiente.

(2022). Coral Reef Restoration in the Maldives: an assessment of techniques and challenges. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2022).

Coral Reef Restoration in the Maldives: an assessment of techniques and challenges

DEHNERT, INGA
2022

Abstract

Coral reefs, which are among the most biodiverse ecosystems on the planet, are declining at an alarming rate. To counteract the threats posed by climate change and other anthropogenic impacts, conservation efforts such as active coral reef restoration have increased globally. Ecological restoration aims to assist natural recovery and increase coral reefs resilience in an effort to preserve the many functions and services these iconic ecosystems provide to society. Under current climate scenarios, coastal and island populations are the first to suffer from continued ecosystem degradation. For example, the Maldives’ vulnerability to global and local coral reef threats is evident for a nation that lives on shallow reef islands with an economy driven by fisheries and tourism. However, little information is available on suitable, regionally tested coral restoration techniques that could be applied at an ecological meaningful scale in the Maldives. ‘Coral gardening’, which comprises fragment farming in coral nurseries followed by the transplantation of these corals to a restoration site, appears particularly suitable for remote locations like the Maldives. The method can be applied by local communities or tourism stakeholders to assist local reef recovery, while creating awareness, stewardship and even income opportunities. This research assesses the application of ‘coral gardening’ for upscaled coral restoration efforts in the Maldives, providing the necessary regional validation and useful insights into the various aspects of this technique for the first time. To evaluate the suitability and performance of this restoration approach across different regions and farming habitats (i.e., lagoon and reef), a total of six mid-water coral rope nurseries were assessed on the local island of Magoodhoo in Faafu Atoll and on Athuruga resort island in Alif Dhaal Atoll. Coral gardening success was examined for three different coral genera, namely Acropora, Pocillopora and Porites, using a common monitoring protocol. This delivered regional benchmarks for fragment growth over time and at different depths as well as coral survival, which typically exceeded 90% in both farming habitats. In addition, ecological interactions were investigated by including mutualistic fauna and predator associations in the assessments of farmed and transplanted corals. For example, a positive correlation between Trapezia guard crabs and farming stock health was observed, while the corallivorous nudibranch Phestilla is newly reported on coral nursery stock. Coral restoration demand and success is further reviewed in the context of natural reef recovery on the restoration site as well as potential ecological implications of restoration activities. Here, coral outplanting was successful and significantly benefitted the degraded reef environment, increasing fish abundance and diversity along with natural coral cover While the overall study results are encouraging, this research also addresses potential risks to coral restoration success, in particular the negative effects of prolonged monitoring and maintenance disruptions and the impacts of coral disease occurrence. Using a number of real case studies, it is demonstrated how these factors can diminish coral gardening outcomes and project success, if not managed in time. Overall, the findings presented and the practical applications concluded from this work hope to provide a scientific baseline for future restoration efforts that can guides restoration practitioners towards efficient conservation work.
GALLI, PAOLO
PADOA SCHIOPPA, EMILIO
coral gardening; scogliera corallina; trapianto; vivaio sospeso; restauro ecologico
coral gardening; coral reef; transplantation; coral nursery; restauro ecologico
BIO/07 - ECOLOGIA
English
24-mag-2022
SCIENZE CHIMICHE, GEOLOGICHE E AMBIENTALI
34
2020/2021
open
(2022). Coral Reef Restoration in the Maldives: an assessment of techniques and challenges. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2022).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/384692
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