The crown-of-thorns starfish (Acanthaster plancii) is one of the most effective coral predators in Indo-Pacific coral reefs. Its biological traits, such as high fecundity, pelagic larval dispersal, and opportunistic feeding, enhance its capacity to form dense and ecologically disruptive aggregations. Furthermore, by preying on reef-building corals, particularly fast-growing species, it can trigger widespread coral mortality and structural degradation. The Gulf of Oman, particularly the reef sites of Hole in the Wall and Martini Bay (Khor Fakkan), experienced a first outbreak in January 2024 and remains particularly vulnerable to recurring infestations. This study aimed to investigate the population dynamics, feeding preferences, and genetic identity of individuals of Acanthaster spp. resembling different species morphologically, and evaluate the short-term effectiveness of targeted culling as a control measure. Fieldwork was conducted between January and June 2024 using a multi-method approach. Coral cover and benthic composition were assessed through photo-quadrat surveys and analysed with Coral Point Count with Excel. Roving diver observations provided data on prey selectivity, individual size distribution, and relative abundance. Tissue samples from collected individuals were processed for molecular and phylogenetic analysis to assess haplotype diversity. Manual culling operations were carried out in June 2024 to reduce population density and assess potential ecological response. Results revealed a genetically homogeneous A. plancii population with low haplotype diversity. Coral cover was dominated by Porites, which showed clear signs of feeding avoidance. Selective predation on other taxa and a predominance of adult individuals were observed. Notably, culling efforts resulted in an 86% reduction in starfish density, indicating their immediate efficacy as a mitigation strategy. This study presents the first comprehensive assessment of A. plancii outbreaks in the Gulf of Oman, underscoring the importance of ongoing monitoring, genetic surveillance, and targeted management, including controlled culling, to enhance coral reef resilience in the face of increasing ecological pressure.
Concari, E., Montalbetti, E., Maggioni, D., Cerri, F., Stahl, H., Landes, A., et al. (2025). New insights on Acanthaster plancii outbreak in the Gulf of Oman (United Arab Emirates). In BOOK OF ABSTRACTS XXXIV Congresso Nazionale della Società Italiana di Ecologia Ecologia e sostenibilità: strategie per affrontare le sfide del terzo millennio (Libro degli abstract presentati al XXXIV Congresso della Società Italiana di Ecologia “Ecologia e sostenibilità: strategie per affrontare le sfide del terzo millennio” — Caserta, 17 – 19 Settembre 2025.) (pp.11-11).
New insights on Acanthaster plancii outbreak in the Gulf of Oman (United Arab Emirates)
Concari, E
Primo
;Montalbetti, ESecondo
;Maggioni, D;Cerri, F;Galli, P;Seveso, D.Ultimo
2025
Abstract
The crown-of-thorns starfish (Acanthaster plancii) is one of the most effective coral predators in Indo-Pacific coral reefs. Its biological traits, such as high fecundity, pelagic larval dispersal, and opportunistic feeding, enhance its capacity to form dense and ecologically disruptive aggregations. Furthermore, by preying on reef-building corals, particularly fast-growing species, it can trigger widespread coral mortality and structural degradation. The Gulf of Oman, particularly the reef sites of Hole in the Wall and Martini Bay (Khor Fakkan), experienced a first outbreak in January 2024 and remains particularly vulnerable to recurring infestations. This study aimed to investigate the population dynamics, feeding preferences, and genetic identity of individuals of Acanthaster spp. resembling different species morphologically, and evaluate the short-term effectiveness of targeted culling as a control measure. Fieldwork was conducted between January and June 2024 using a multi-method approach. Coral cover and benthic composition were assessed through photo-quadrat surveys and analysed with Coral Point Count with Excel. Roving diver observations provided data on prey selectivity, individual size distribution, and relative abundance. Tissue samples from collected individuals were processed for molecular and phylogenetic analysis to assess haplotype diversity. Manual culling operations were carried out in June 2024 to reduce population density and assess potential ecological response. Results revealed a genetically homogeneous A. plancii population with low haplotype diversity. Coral cover was dominated by Porites, which showed clear signs of feeding avoidance. Selective predation on other taxa and a predominance of adult individuals were observed. Notably, culling efforts resulted in an 86% reduction in starfish density, indicating their immediate efficacy as a mitigation strategy. This study presents the first comprehensive assessment of A. plancii outbreaks in the Gulf of Oman, underscoring the importance of ongoing monitoring, genetic surveillance, and targeted management, including controlled culling, to enhance coral reef resilience in the face of increasing ecological pressure.
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