Mehdi Adjeroud - Academia.edu (original) (raw)
Papers by Mehdi Adjeroud
Revue d'Écologie (La Terre et La Vie)
... Avec l'aide du WWF France, Mehdi Adjeroud et Carlos Gonzales Salas se sont acquittés... more ... Avec l'aide du WWF France, Mehdi Adjeroud et Carlos Gonzales Salas se sont acquittés de cette tâche (Adjeroud & Gonzales Salas ... LOVELL, E., SYKES, H., DEIYE, M., WANTIEZ, L., GARRIGUE, C., VIRLY, S., SAMUELU, J., SOLOFA, A., POULASI, T., PAKOA, K., SABETIAN, A ...
PLOS ONE
Madagascar is a major hotspot of biodiversity in the Western Indian Ocean, but, as in many other ... more Madagascar is a major hotspot of biodiversity in the Western Indian Ocean, but, as in many other regions, coral reefs surrounding the island confront large-scale disturbances and human-induced local stressors. Conservation actions have been implemented with encouraging results for fisheries, though their benefit on coral assemblages has never been rigorously addressed. In this context, we analyzed the multiscale spatial variation of the composition, generic richness, abundance, life history strategies, and cover of coral assemblages among 18 stations placed at three regions around the island. The potential influences of marine protected areas (MPAs), algal cover, substrate rugosity, herbivorous fish biomass, and geographic location were also analyzed. Our results highlight the marked spatial variability, with variation at either or both regional and local scales for all coral descriptors. The northeast coastal region of Masoala was characterized by the high abundance of coral coloni...
Marine Ecology Progress Series
Recruitment processes largely drive spatial distributions, dynamics, and recovery potential of ma... more Recruitment processes largely drive spatial distributions, dynamics, and recovery potential of marine communities. Determining scales of variation in recruitment rates and composition can help in understanding population replenishment mechanisms, while identifying recruitment hotspots is crucial for improving conservation strategies, particularly for threatened marine ecosystems such as coral reefs. We examined the spatial and interannual variability (2012-2014) of coral recruitment at multiple scales within and among reef habitats (14 stations) in the southwestern lagoon of New Caledonia. Recruit assemblages were characterized by high recruitment rates compared to other regions (overall mean of 34.9 recruits per 11 × 11 × 1 cm settlement tile, corresponding to 1220.9 recruits m-2) and strong dominance of Acroporidae. We found a marked spatial heterogeneity among habitats but also exceptionally high interannual variation (100-fold), with extreme recruitment peaks (up to 13572.8 recr...
Diversity, 2021
Despite increased attention over the last decade on Mesophotic Coral Ecosystems (MCEs) [...]
This study examined patterns of sexual reproduction, embryogenesis, larval development, planulae ... more This study examined patterns of sexual reproduction, embryogenesis, larval development, planulae metamorphosis and settlement competency of <em>Acropora</em> reef corals on outer reef slope and lagoonal reefs at Moorea, French Polynesia, during 2002 to 2004. The spatial heterogeneity of consecutive coral bleaching events in 2002 and 2003 and their impact on <em>Acropora</em> gametogenesis were also investigated.
Table S6. Variations in bacterial (16S rRNA gene) and Symbiodinium (ITS2) communities explained b... more Table S6. Variations in bacterial (16S rRNA gene) and Symbiodinium (ITS2) communities explained by the addition of significant variables for the reduced models identified using RDA and forwardselection procedures. (XLSX 38Â kb)
Table S3. Bacterial OTU table with sequence tag counts per sample and taxonomic affiliation. (XLS... more Table S3. Bacterial OTU table with sequence tag counts per sample and taxonomic affiliation. (XLSX 49Â kb)
Table S2. Symbiodinium OTU table with sequence tag counts per sample and taxonomic affiliation (X... more Table S2. Symbiodinium OTU table with sequence tag counts per sample and taxonomic affiliation (XLSX 62Â kb)
Outbreaks of the predator crown-of-thorns seastar (COTS) Acanthaster planci cause widespread cora... more Outbreaks of the predator crown-of-thorns seastar (COTS) Acanthaster planci cause widespread coral mortality across the Indo-Pacific. Like many marine invertebrates, COTS is a nocturnal species whose cryptic behaviour during the day can affect its detectability, particularly in structurally complex reef habitats that provide many refuges for benthic creatures. We performed extensive day and night surveys of COTS populations in coral reef habitats showing differing levels of structural complexity and COTS abundance. We tested whether estimations of COTS density varied between day and night observations, and if the differences were related to changes in COTS abundance, reef structural complexity, and the spatial scale of observation. Estimations of COTS density were on average 27% higher at night than during the day. Differences in COTS detection varied with changing seastar abundance but not reef structural complexity or scale of observation. Underestimation of COTS abundance in daytime was significant for a broad seastar density range, thus potentially affecting most outbreak events. Our study suggests that portions of COTS populations can be undetected during conventional surveys and control campaigns, which are exclusively conducted by day, and significantly affect the trajectory of coral reefs. Accounting for bias in COTS detection can strengthen coral reef management broadly
Figure S1. Maximum-likelihood tree of the mitochondrial ORF-defining Pocillopora types. Numbers a... more Figure S1. Maximum-likelihood tree of the mitochondrial ORF-defining Pocillopora types. Numbers are bootstraps (%) reflecting clade support. (PPTX 307Â kb)
Table S1. Sample metadata including geographic and abiotic variables (temperature descriptors) as... more Table S1. Sample metadata including geographic and abiotic variables (temperature descriptors) as well as Pocillopora haplotype identification. (XLSX 55Â kb)
Outbreaks of the corallivorous crown-of-thorns seastar Acanthaster planci (COTS) repre-sent one o... more Outbreaks of the corallivorous crown-of-thorns seastar Acanthaster planci (COTS) repre-sent one of the greatest disturbances to coral reef ecosystems in the Indo-Pacific, affecting not only coral reefs but also the coastal communities which rely on their resources. While injection approaches are increasingly used in an attempt to control COTS densities, most of them display severe drawbacks including logistical challenges, high residual environmental impacts or low cost-effectiveness. We tested a new alternative control method based upon acidic injections of cheap, 100 % natural products. We investigated the lethal doses, intra-and inter-specific disease transmission and immune responses of COTS when injected with fresh lime juice (extracted from local Citrus arantifolia) and white spirit vinegar. High COTS mortality was achieved with small volumes: 10–20 ml per seastar induced death in 89%/ 97 % of injected specimens after an average 34.3 h/29.8 h for lime juice and vinegar respec-...
Human-induced physical disturbances and their indicators on coral reef habitats: A multi-scale ap... more Human-induced physical disturbances and their indicators on coral reef habitats: A multi-scale approach
Zoological studies, 2018
Mehdi Adjeroud, Mohsen Kayal, Christophe Peignon, Matthieu Juncker, Suzanne C. Mills, Ricardo Bel... more Mehdi Adjeroud, Mohsen Kayal, Christophe Peignon, Matthieu Juncker, Suzanne C. Mills, Ricardo Beldade, and Pascal Dumas (2018) Outbreaks of the coral predator Acanthaster spp., the crown-of-thorns seastar (COTS), cause major coral declines across the Indo-Pacific. However, the processes surrounding the initiation and propagation of COTS outbreaks are still unclear. We observed COTS outbreak abundances on several mid-shelf and inner-barrier reefs in the southern section of the New Caledonian lagoon, a multi-location initiation event that we expected to precede a broader region-wide disturbance. However, reef monitoring over 3 years revealed the highly localized and ephemeral character of these outbreaks. Outbreaks that were observed at four reef locations at the beginning of the survey simply faded away, without any specific management actions such as culling efforts. We also found no distinct reef biotope on which COTS outbreaks originated, although mid-shelf and inner-shelf barrier...
Coral communities are highly shaped by the combined effect of predation and competition. Intensit... more Coral communities are highly shaped by the combined effect of predation and competition. Intensities of these regulation pathways vary in time and space, occasionally reaching extremes with drastic impacts on corals. Acanthaster planci is a major predator whose population outbreak considerably affects coral communities. In order to understand how predation and competition affect coral during such events, an experimental study was conducted on Moorea (French Polynesia) where high A. planci densities were observed. Predation and competition were controlled by caging and removal experiments respectively. In order to determine the respective and synergistic impacts of predation and competition on coral assemblages, treatments were applied to colonies belonging to the main coral taxa (Acropora, Pocillopora, Porites) following a factorial design. After 100 days, high Acanthaster densities resulted in considerable mortality. On control colonies, Acropora was the most affected taxa with 92%...
Amidst global environmental changes, predicting species responses to future environments is a cri... more Amidst global environmental changes, predicting species responses to future environments is a critical challenge for preserving biodiversity and associated human benefits. We explored the original idea that coral competitive performances, the ability of corals to preempt ecological space on the reef through territorial warfare, serve as indicators of species’ ecological niches and environmental windows, and therefore, responses to future environments. Our surveys indicated that coral performances varied with taxonomic-identity, size, and position along environmental gradients, highlighting complex interplays between life-history, warfare-strategy, and niche segregation. Our results forewarn that growing alterations of coastal environments may trigger shifts in coral dominance, with decline of major reef-building taxa like acroporids, and underscore the importance of restraining human impacts for coastal resilience. Our empirical approach untangles the complexity of species’ battle-l...
Scleractinian corals are of great ecological interest as ecosystem engineer species. Accordingly,... more Scleractinian corals are of great ecological interest as ecosystem engineer species. Accordingly, there is a wealth of studies on their adaptive abilities facing climate change. Such studies should rely on precise species and population delimitation. Nevertheless species delimitation in corals can be hindered by the lack of adequate genetic markers, by hybridization, and by morphological plasticity. Here we applied RAD sequencing to the study of species delimitation and genetic structure in populations of Pocillopora spp. from Oman and French Polynesia with the objectives to test primary species hypotheses based on mitochondrial DNA sequencing, and to study the genetic structure among sampling sites inside species. Regarding the varying levels of missing data observed among samples we tested different filtering strategy. The main genetic differentiation was observed between samples from Oman and French Polynesia, which also corresponded to different mitochondrial lineages and specie...
Revue d'Écologie (La Terre et La Vie)
... Avec l'aide du WWF France, Mehdi Adjeroud et Carlos Gonzales Salas se sont acquittés... more ... Avec l'aide du WWF France, Mehdi Adjeroud et Carlos Gonzales Salas se sont acquittés de cette tâche (Adjeroud & Gonzales Salas ... LOVELL, E., SYKES, H., DEIYE, M., WANTIEZ, L., GARRIGUE, C., VIRLY, S., SAMUELU, J., SOLOFA, A., POULASI, T., PAKOA, K., SABETIAN, A ...
PLOS ONE
Madagascar is a major hotspot of biodiversity in the Western Indian Ocean, but, as in many other ... more Madagascar is a major hotspot of biodiversity in the Western Indian Ocean, but, as in many other regions, coral reefs surrounding the island confront large-scale disturbances and human-induced local stressors. Conservation actions have been implemented with encouraging results for fisheries, though their benefit on coral assemblages has never been rigorously addressed. In this context, we analyzed the multiscale spatial variation of the composition, generic richness, abundance, life history strategies, and cover of coral assemblages among 18 stations placed at three regions around the island. The potential influences of marine protected areas (MPAs), algal cover, substrate rugosity, herbivorous fish biomass, and geographic location were also analyzed. Our results highlight the marked spatial variability, with variation at either or both regional and local scales for all coral descriptors. The northeast coastal region of Masoala was characterized by the high abundance of coral coloni...
Marine Ecology Progress Series
Recruitment processes largely drive spatial distributions, dynamics, and recovery potential of ma... more Recruitment processes largely drive spatial distributions, dynamics, and recovery potential of marine communities. Determining scales of variation in recruitment rates and composition can help in understanding population replenishment mechanisms, while identifying recruitment hotspots is crucial for improving conservation strategies, particularly for threatened marine ecosystems such as coral reefs. We examined the spatial and interannual variability (2012-2014) of coral recruitment at multiple scales within and among reef habitats (14 stations) in the southwestern lagoon of New Caledonia. Recruit assemblages were characterized by high recruitment rates compared to other regions (overall mean of 34.9 recruits per 11 × 11 × 1 cm settlement tile, corresponding to 1220.9 recruits m-2) and strong dominance of Acroporidae. We found a marked spatial heterogeneity among habitats but also exceptionally high interannual variation (100-fold), with extreme recruitment peaks (up to 13572.8 recr...
Diversity, 2021
Despite increased attention over the last decade on Mesophotic Coral Ecosystems (MCEs) [...]
This study examined patterns of sexual reproduction, embryogenesis, larval development, planulae ... more This study examined patterns of sexual reproduction, embryogenesis, larval development, planulae metamorphosis and settlement competency of <em>Acropora</em> reef corals on outer reef slope and lagoonal reefs at Moorea, French Polynesia, during 2002 to 2004. The spatial heterogeneity of consecutive coral bleaching events in 2002 and 2003 and their impact on <em>Acropora</em> gametogenesis were also investigated.
Table S6. Variations in bacterial (16S rRNA gene) and Symbiodinium (ITS2) communities explained b... more Table S6. Variations in bacterial (16S rRNA gene) and Symbiodinium (ITS2) communities explained by the addition of significant variables for the reduced models identified using RDA and forwardselection procedures. (XLSX 38Â kb)
Table S3. Bacterial OTU table with sequence tag counts per sample and taxonomic affiliation. (XLS... more Table S3. Bacterial OTU table with sequence tag counts per sample and taxonomic affiliation. (XLSX 49Â kb)
Table S2. Symbiodinium OTU table with sequence tag counts per sample and taxonomic affiliation (X... more Table S2. Symbiodinium OTU table with sequence tag counts per sample and taxonomic affiliation (XLSX 62Â kb)
Outbreaks of the predator crown-of-thorns seastar (COTS) Acanthaster planci cause widespread cora... more Outbreaks of the predator crown-of-thorns seastar (COTS) Acanthaster planci cause widespread coral mortality across the Indo-Pacific. Like many marine invertebrates, COTS is a nocturnal species whose cryptic behaviour during the day can affect its detectability, particularly in structurally complex reef habitats that provide many refuges for benthic creatures. We performed extensive day and night surveys of COTS populations in coral reef habitats showing differing levels of structural complexity and COTS abundance. We tested whether estimations of COTS density varied between day and night observations, and if the differences were related to changes in COTS abundance, reef structural complexity, and the spatial scale of observation. Estimations of COTS density were on average 27% higher at night than during the day. Differences in COTS detection varied with changing seastar abundance but not reef structural complexity or scale of observation. Underestimation of COTS abundance in daytime was significant for a broad seastar density range, thus potentially affecting most outbreak events. Our study suggests that portions of COTS populations can be undetected during conventional surveys and control campaigns, which are exclusively conducted by day, and significantly affect the trajectory of coral reefs. Accounting for bias in COTS detection can strengthen coral reef management broadly
Figure S1. Maximum-likelihood tree of the mitochondrial ORF-defining Pocillopora types. Numbers a... more Figure S1. Maximum-likelihood tree of the mitochondrial ORF-defining Pocillopora types. Numbers are bootstraps (%) reflecting clade support. (PPTX 307Â kb)
Table S1. Sample metadata including geographic and abiotic variables (temperature descriptors) as... more Table S1. Sample metadata including geographic and abiotic variables (temperature descriptors) as well as Pocillopora haplotype identification. (XLSX 55Â kb)
Outbreaks of the corallivorous crown-of-thorns seastar Acanthaster planci (COTS) repre-sent one o... more Outbreaks of the corallivorous crown-of-thorns seastar Acanthaster planci (COTS) repre-sent one of the greatest disturbances to coral reef ecosystems in the Indo-Pacific, affecting not only coral reefs but also the coastal communities which rely on their resources. While injection approaches are increasingly used in an attempt to control COTS densities, most of them display severe drawbacks including logistical challenges, high residual environmental impacts or low cost-effectiveness. We tested a new alternative control method based upon acidic injections of cheap, 100 % natural products. We investigated the lethal doses, intra-and inter-specific disease transmission and immune responses of COTS when injected with fresh lime juice (extracted from local Citrus arantifolia) and white spirit vinegar. High COTS mortality was achieved with small volumes: 10–20 ml per seastar induced death in 89%/ 97 % of injected specimens after an average 34.3 h/29.8 h for lime juice and vinegar respec-...
Human-induced physical disturbances and their indicators on coral reef habitats: A multi-scale ap... more Human-induced physical disturbances and their indicators on coral reef habitats: A multi-scale approach
Zoological studies, 2018
Mehdi Adjeroud, Mohsen Kayal, Christophe Peignon, Matthieu Juncker, Suzanne C. Mills, Ricardo Bel... more Mehdi Adjeroud, Mohsen Kayal, Christophe Peignon, Matthieu Juncker, Suzanne C. Mills, Ricardo Beldade, and Pascal Dumas (2018) Outbreaks of the coral predator Acanthaster spp., the crown-of-thorns seastar (COTS), cause major coral declines across the Indo-Pacific. However, the processes surrounding the initiation and propagation of COTS outbreaks are still unclear. We observed COTS outbreak abundances on several mid-shelf and inner-barrier reefs in the southern section of the New Caledonian lagoon, a multi-location initiation event that we expected to precede a broader region-wide disturbance. However, reef monitoring over 3 years revealed the highly localized and ephemeral character of these outbreaks. Outbreaks that were observed at four reef locations at the beginning of the survey simply faded away, without any specific management actions such as culling efforts. We also found no distinct reef biotope on which COTS outbreaks originated, although mid-shelf and inner-shelf barrier...
Coral communities are highly shaped by the combined effect of predation and competition. Intensit... more Coral communities are highly shaped by the combined effect of predation and competition. Intensities of these regulation pathways vary in time and space, occasionally reaching extremes with drastic impacts on corals. Acanthaster planci is a major predator whose population outbreak considerably affects coral communities. In order to understand how predation and competition affect coral during such events, an experimental study was conducted on Moorea (French Polynesia) where high A. planci densities were observed. Predation and competition were controlled by caging and removal experiments respectively. In order to determine the respective and synergistic impacts of predation and competition on coral assemblages, treatments were applied to colonies belonging to the main coral taxa (Acropora, Pocillopora, Porites) following a factorial design. After 100 days, high Acanthaster densities resulted in considerable mortality. On control colonies, Acropora was the most affected taxa with 92%...
Amidst global environmental changes, predicting species responses to future environments is a cri... more Amidst global environmental changes, predicting species responses to future environments is a critical challenge for preserving biodiversity and associated human benefits. We explored the original idea that coral competitive performances, the ability of corals to preempt ecological space on the reef through territorial warfare, serve as indicators of species’ ecological niches and environmental windows, and therefore, responses to future environments. Our surveys indicated that coral performances varied with taxonomic-identity, size, and position along environmental gradients, highlighting complex interplays between life-history, warfare-strategy, and niche segregation. Our results forewarn that growing alterations of coastal environments may trigger shifts in coral dominance, with decline of major reef-building taxa like acroporids, and underscore the importance of restraining human impacts for coastal resilience. Our empirical approach untangles the complexity of species’ battle-l...
Scleractinian corals are of great ecological interest as ecosystem engineer species. Accordingly,... more Scleractinian corals are of great ecological interest as ecosystem engineer species. Accordingly, there is a wealth of studies on their adaptive abilities facing climate change. Such studies should rely on precise species and population delimitation. Nevertheless species delimitation in corals can be hindered by the lack of adequate genetic markers, by hybridization, and by morphological plasticity. Here we applied RAD sequencing to the study of species delimitation and genetic structure in populations of Pocillopora spp. from Oman and French Polynesia with the objectives to test primary species hypotheses based on mitochondrial DNA sequencing, and to study the genetic structure among sampling sites inside species. Regarding the varying levels of missing data observed among samples we tested different filtering strategy. The main genetic differentiation was observed between samples from Oman and French Polynesia, which also corresponded to different mitochondrial lineages and specie...