Coral reefs provide coastal protection for communities, habitat for fish and invertebrates, and additionally contribute to generating millions of dollars to recreational activities (i.e. SCUBA diving) and tourism. However, corals are also severely threatened by rapidly worsening environmental conditions due to natural and anthropogenic effects (changing water temperatures, ocean acidification, pollution, sedimentation, invasive species, changing weather patterns, and physical impacts from ship groundings and storms). Koh Tao, a renowned tourist destination in Thailand, faces significant anthropogenic impacts on its marine environment, particularly its coral reefs. The unregulated tourism activities, such as snorkelling, diving, and boating, have resulted in detrimental consequences for coral reefs. They have caused physical damage to the reefs and have also contributed to an increased spread of diseases. Pollution from untreated sewage, chemicals, and coastal development compounds the issue, while overfishing and destructive fishing practices disrupt the balance of the coral reef ecosystems. Additionally, the effects of climate change, such as rising sea temperatures and coral bleaching events, pose a grave threat to the reefs in Koh Tao. As a result, a coral restoration program becomes essential to restore and conserve these ecosystems. Data has been collected following an ecological monitoring program called "Save Koh Tao Ecological Monitoring Program" (Scott, 2012). This program aims to rehabilitate coral reefs and promote their long-term health and resilience, with the contribution of various local diving schools, such as the NEW HEAVEN DIVING SCHOOL, which assist in training interns through specialized courses. Through activities like transplantation, artificial reef construction, the program aims to rehabilitate the coral reefs and promote their long-term health and resilience. Main objective of this project is to contribute to corals’ restoration techniques by comparing growth rates of corals’ cuts transplanted on three types of artificial devices (iron, concrete, and water electrified structures). The hypothesis to be tested is that there are no differences in survival/growth rates of corals reared on the different devices. Furthermore, this project focuses on transplanting both fast-growing branching corals, which typically naturally recruit well but tend to survive transplantation and re-location relatively poorly, and massive corals, which generally survive transplantation well but often recruit slowly. Corals’ fragments were placed on three artificial structures (i.e., mineral accretion device, concrete and iron), located at the same dive site (Auw leuk, Koh Tao Island), and subjected to the same environmental conditions (currents, depth, distance from the natural reef) were monitored for six months (April- November 2022) to collect growth data by photo-sampling techniques. The results show that during the monitoring period (six months), the corals on the iron structure exhibit the highest growth rates, although no significant differences were observed in the growth rates of the transplanted corals on the three types of substrates. Finally, the growth rates of the transplanted coral colonies in Koh Tao were compared with those obtained in other similar experiments in order to highlight the strengths and weaknesses of each technique and provide guidance to increase the chances of success in coral transplantation.
Le scogliere coralline offrono protezione costiera per le comunità, habitat per pesci e invertebrati, inoltre, contribuiscono a generare milioni di dollari attraverso attività ricreative come l'immersione subacquea e il turismo. Tuttavia, i coralli sono anche gravemente minacciati dalle condizioni ambientali che peggiorano rapidamente a causa di effetti naturali e antropogenici (cambiamenti della temperatura dell'acqua, acidificazione degli oceani, inquinamento, sedimentazione, specie invasive, e impatti meccanici derivanti da tempeste). Koh Tao, rappresenta una rinomata meta turistica in Thailandia, questo contribuisce ad aumentare significativamente gli effetti negativi dell’azione dell’uomo, in particolare sulle sue scogliere coralline. Le conseguenze del turismo non regolamentato, tra cui attività come lo snorkeling, le immersioni subacquee e la navigazione, hanno portato a danni fisici contribuendo anche ad un incremento della diffusione di malattie. L'inquinamento derivante da scarichi fognari non trattati, prodotti chimici ed il notevole sviluppo costiero complicano la situazione, mentre la pesca eccessiva e le pratiche di pesca distruttive disturbano l'equilibrio degli ecosistemi corallini. Inoltre, gli effetti dei cambiamenti climatici, come l'aumento delle temperature del mare e lo sbiancamento dei coralli, rappresentano una grave minaccia per le scogliere coralline di Koh Tao. Di conseguenza, diventa essenziale un programma per aumentare lo stato di conservazione e restauro del reef. I dati sono stati raccolti seguendo il programma di monitoraggio ecologico chiamato "Save Koh Tao Ecological Monitoring Program" (Scott, 2012). Questo programma mira a riabilitare le scogliere coralline e promuovere la loro salute e resilienza a lungo termine grazie al contributo di diverse scuole di diving locali, in questo caso il NEW HEAVEN DIVING SCHOOL, che contribuiscono a formare tirocinanti attraverso corsi specializzanti. Attraverso attività come il trapianto e la costruzione di strutture artificiali, il programma mira a riabilitare le scogliere coralline e promuovere la loro salute e resilienza a lungo termine. L'obiettivo principale di questo progetto è contribuire alle tecniche di restauro degli ecosistemi corallini confrontando i tassi di crescita di frammenti di corallo trapiantati su tre tipi di strutture artificiali (ferro, cemento e strutture elettrificate). L'ipotesi da testare è che non vi siano differenze nei tassi di crescita dei coralli allevati sulle diverse strutture. Inoltre, questo progetto si concentra sul trapianto di coralli a crescita rapida, che di solito si insediano naturalmente ma tendono a sopravvivere male al trapianto e alla ricollocazione, e di coralli massivi, che generalmente sopravvivono bene al trapianto ma spesso si insediano lentamente. I frammenti di corallo sono stati posizionati su tre strutture artificiali (cioè, dispositivo di accrescimento minerale, strutture di cemento e di ferro), situate nello stesso sito di immersione (Auw leuk, Isola di Koh Tao) e sottoposte alle stesse condizioni ambientali (correnti, profondità, distanza dalla barriera corallina naturale). I frammenti posizionati sono stati monitorati per sei mesi (aprile-novembre 2022) per raccogliere dati sulla sopravvivenza/crescita mediante tecniche di campionamento. I risultati mostrano che, durante il periodo di monitoraggio (sei mesi), i coralli sulla struttura in ferro presentano i tassi di crescita più elevati, anche se non sono state riscontrate differenze significative nei tassi di crescita dei coralli traslocati sulle tre tipologie di substrato. Infine, i tassi di crescita delle colonie di corallo trapiantate a Koh Tao sono stati confrontati con quelli ottenuti in altri esperimenti simili in modo da mettere in evidenza punti forza e debolezza di ciascuna tecnica e fornire indicazioni per aumentare le probabilità di successo dei trapianti di corallo.
Analisi Comparativa dei Tassi di Crescita di Frammenti di Corallo su Diversi Tipi di Substrati per la Costruzione di Reef Artificiali nella Baia di Aow Leuk, Koh Tao, Thailandia.
DI FABIO, LUCREZIA
2022/2023
Abstract
Coral reefs provide coastal protection for communities, habitat for fish and invertebrates, and additionally contribute to generating millions of dollars to recreational activities (i.e. SCUBA diving) and tourism. However, corals are also severely threatened by rapidly worsening environmental conditions due to natural and anthropogenic effects (changing water temperatures, ocean acidification, pollution, sedimentation, invasive species, changing weather patterns, and physical impacts from ship groundings and storms). Koh Tao, a renowned tourist destination in Thailand, faces significant anthropogenic impacts on its marine environment, particularly its coral reefs. The unregulated tourism activities, such as snorkelling, diving, and boating, have resulted in detrimental consequences for coral reefs. They have caused physical damage to the reefs and have also contributed to an increased spread of diseases. Pollution from untreated sewage, chemicals, and coastal development compounds the issue, while overfishing and destructive fishing practices disrupt the balance of the coral reef ecosystems. Additionally, the effects of climate change, such as rising sea temperatures and coral bleaching events, pose a grave threat to the reefs in Koh Tao. As a result, a coral restoration program becomes essential to restore and conserve these ecosystems. Data has been collected following an ecological monitoring program called "Save Koh Tao Ecological Monitoring Program" (Scott, 2012). This program aims to rehabilitate coral reefs and promote their long-term health and resilience, with the contribution of various local diving schools, such as the NEW HEAVEN DIVING SCHOOL, which assist in training interns through specialized courses. Through activities like transplantation, artificial reef construction, the program aims to rehabilitate the coral reefs and promote their long-term health and resilience. Main objective of this project is to contribute to corals’ restoration techniques by comparing growth rates of corals’ cuts transplanted on three types of artificial devices (iron, concrete, and water electrified structures). The hypothesis to be tested is that there are no differences in survival/growth rates of corals reared on the different devices. Furthermore, this project focuses on transplanting both fast-growing branching corals, which typically naturally recruit well but tend to survive transplantation and re-location relatively poorly, and massive corals, which generally survive transplantation well but often recruit slowly. Corals’ fragments were placed on three artificial structures (i.e., mineral accretion device, concrete and iron), located at the same dive site (Auw leuk, Koh Tao Island), and subjected to the same environmental conditions (currents, depth, distance from the natural reef) were monitored for six months (April- November 2022) to collect growth data by photo-sampling techniques. The results show that during the monitoring period (six months), the corals on the iron structure exhibit the highest growth rates, although no significant differences were observed in the growth rates of the transplanted corals on the three types of substrates. Finally, the growth rates of the transplanted coral colonies in Koh Tao were compared with those obtained in other similar experiments in order to highlight the strengths and weaknesses of each technique and provide guidance to increase the chances of success in coral transplantation.| File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12075/14192