The Experts below are selected from a list of 90 Experts worldwide ranked by ideXlab platform
Serge Planes - One of the best experts on this subject based on the ideXlab platform.
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human induced shifts in habitat use and behaviour of a marine predator the effects of bait provisioning in the Blacktip Reef Shark
Animal Conservation, 2020Co-Authors: Johann Mourier, Joachim Claudet, Serge PlanesAbstract:While the negative effects of consumptive pressures on marine predators are well established, the effects of increasing non‐consumptive activities such as wildlife tourism are still understudied. As such, the long‐term effects of the provision of bait on Shark behaviour are still unclear. Here, we assessed the effects of provisioning using a Control‐Impact design on the spatial use and level of residency of the Blacktip Reef Shark Carcharhinus melanopterus over a 2‐year period. We used effect sizes to model the relative changes in residency between provisioning and non‐provisioning sites. Sharks showed a high degree of residency and significant changes in their habitat use which persisted overnight while the activity ceased. We suggest that provisioning activities can affect species with high level of residency such as the Blacktip Reef Shark. Further research is needed to better understand how these behavioural modifications can alter the fitness of this species. It is important to adapt Shark provisioning activities to limit the induced changes in habitat use.
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human induced shifts in habitat use and behaviour of a marine predator the effects of bait provisioning in the Blacktip Reef Shark
Animal Conservation, 2020Co-Authors: Johann Mourier, Joachim Claudet, Serge PlanesAbstract:While the negative effects of consumptive pressures on marine predators are well established, the effects of increasing non-consumptive activities wildlife tourism are still understudied. As such, the long-term effects of the provision of bait on Shark behaviour are still unclear. Here, we assessed the effects of provisioning using a Control-Impact design on the spatial use and level of residency of the Blacktip Reef Shark (Carcharhinus melanopterus) over a two-year period. We used effect sizes to model the differences relative changes in residency between provisioning and non-provisioning sites. Sharks showed a high degree of residency and significant changes in their habitat use which persisted overnight while the activity ceased. We suggest that provisioning activities can affect species with high level of residency such as the Blacktip Reef Shark. Further research is needed to better understand how these changes behavioural modifications can alter the fitness of this species. It is important to adapt Shark provisioning activities to limit the induced changes in habitat.
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thermal tolerance and hypoxia tolerance are associated in Blacktip Reef Shark carcharhinus melanopterus neonates
The Journal of Experimental Biology, 2020Co-Authors: Serge Planes, Ian A Bouyoucos, Phillip R Morrison, Ornella C Weideli, Eva Jacquesson, Colin A Simpfendorfer, Colin J Brauner, Jodie L RummerAbstract:ABSTRACT Thermal dependence of growth and metabolism can influence thermal preference and tolerance in marine ectotherms, including threatened and data-deficient species. Here, we quantified the thermal dependence of physiological performance in neonates of a tropical Shark species (Blacktip Reef Shark, Carcharhinus melanopterus) from shallow, nearshore habitats. We measured minimum and maximum oxygen uptake rates (ṀO2), calculated aerobic scope, excess post-exercise oxygen consumption and recovery from exercise, and measured critical thermal maxima (CTmax), thermal safety margins, hypoxia tolerance, specific growth rates, body condition and food conversion efficiencies at two ecologically relevant acclimation temperatures (28 and 31°C). Owing to high post-exercise mortality, a third acclimation temperature (33°C) was not investigated further. Acclimation temperature did not affect ṀO2 or growth, but CTmax and hypoxia tolerance were greatest at 31°C and positively associated. We also quantified in vitro temperature (25, 30 and 35°C) and pH effects on haemoglobin–oxygen (Hb–O2) affinity of wild-caught, non-acclimated Sharks. As expected, Hb–O2 affinity decreased with increasing temperatures, but pH effects observed at 30°C were absent at 25 and 35°C. Finally, we logged body temperatures of free-ranging Sharks and determined that C. melanopterus neonates avoided 31°C in situ. We conclude that C. melanopterus neonates demonstrate minimal thermal dependence of whole-organism physiological performance across a seasonal temperature range and may use behaviour to avoid unfavourable environmental temperatures. The association between thermal tolerance and hypoxia tolerance suggests a common mechanism warranting further investigation. Future research should explore the consequences of ocean warming, especially in nearshore, tropical species.
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kinship does not predict the structure of a Shark social network
bioRxiv, 2020Co-Authors: Johann Mourier, Serge PlanesAbstract:The role of relatedness in animal societies has received important consideration as a process driving social groups. In the marine world, most studies which have investigated this question have focused on marine mammals such as whales and dolphins. For Sharks, recent studies have demonstrated preferential associations among individuals from which social communities emerge. Assortment patterns have been found according to phenotypic or behavioural traits but the role of genetic relatedness and family structure in shaping the social structure of adult Shark populations has never been investigated. Here, we used a social network analysis crossed with DNA microsatellite genotyping to investigate the role of the genetic relatedness in the social structure of a Blacktip Reef Shark (Carcharhinus melanopterus) population. We found an established social network spatially organized but dynamic through time with different communities merging during the mating periods. Such recombination shows the males being more gregarious. Kinship was not a predictor of associations among Sharks both at the dyad or community levels as individuals tended to associate independently and randomly regardless of the genetic relatedness between individuals. The lack of parental care in this species may contribute to the breakdown of family links in the population early in life, thereby preventing the formation of kin-based social networks.
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Demographic inferences after a range expansion can be biased: the test case of the Blacktip Reef Shark (Carcharhinus melanopterus)
Heredity, 2019Co-Authors: Pierpaolo Maisano Delser, Serge Planes, Shannon Corrigan, Drew Duckett, Arnaud Suwalski, Michel Veuille, Gavin J. P. Naylor, Stefano MonaAbstract:The evolutionary history of species is a dynamic process as they modify, expand, and contract their spatial distributions over time. Range expansions (REs) occur through a series of founder events that are followed by migration among neighboring demes. The process usually results in structured metapopulations and leaves a distinct signature in the genetic variability of species. Explicitly modeling the consequences of complex demographic events such as REs is computationally very intensive. Here we propose an an alternative approach that requires less computational effort than a comprehensive RE model, but that can recover the demography of species undergoing a RE, by combining spatially explicit modelling with simplified but realistic metapopulation models. We examine the demographic and colonization history of Carcharhinus melanopterus , an abundant Reef-associated Shark, as a test case. We first used a population genomics approach to statistically confirm the occurrence of a RE in C. melanopterus , and identify its origin in the Indo-Australian Archipelago. Spatial genetic modelling identified two waves of stepping-stone colonization: an eastward wave moving through the Pacific and a westward one moving through the Indian Ocean. We show that metapopulation models best describe the demographic history of this species and that not accounting for this may lead to incorrectly interpreting the observed genetic variation as signals of widespread population bottlenecks. Our study highlights insights that can be gained about demography by coupling metapopulation models with spatial modeling and underscores the need for cautious interpretation of population genetic data when advancing conservation priorities.
Johann Mourier - One of the best experts on this subject based on the ideXlab platform.
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human induced shifts in habitat use and behaviour of a marine predator the effects of bait provisioning in the Blacktip Reef Shark
Animal Conservation, 2020Co-Authors: Johann Mourier, Joachim Claudet, Serge PlanesAbstract:While the negative effects of consumptive pressures on marine predators are well established, the effects of increasing non‐consumptive activities such as wildlife tourism are still understudied. As such, the long‐term effects of the provision of bait on Shark behaviour are still unclear. Here, we assessed the effects of provisioning using a Control‐Impact design on the spatial use and level of residency of the Blacktip Reef Shark Carcharhinus melanopterus over a 2‐year period. We used effect sizes to model the relative changes in residency between provisioning and non‐provisioning sites. Sharks showed a high degree of residency and significant changes in their habitat use which persisted overnight while the activity ceased. We suggest that provisioning activities can affect species with high level of residency such as the Blacktip Reef Shark. Further research is needed to better understand how these behavioural modifications can alter the fitness of this species. It is important to adapt Shark provisioning activities to limit the induced changes in habitat use.
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human induced shifts in habitat use and behaviour of a marine predator the effects of bait provisioning in the Blacktip Reef Shark
Animal Conservation, 2020Co-Authors: Johann Mourier, Joachim Claudet, Serge PlanesAbstract:While the negative effects of consumptive pressures on marine predators are well established, the effects of increasing non-consumptive activities wildlife tourism are still understudied. As such, the long-term effects of the provision of bait on Shark behaviour are still unclear. Here, we assessed the effects of provisioning using a Control-Impact design on the spatial use and level of residency of the Blacktip Reef Shark (Carcharhinus melanopterus) over a two-year period. We used effect sizes to model the differences relative changes in residency between provisioning and non-provisioning sites. Sharks showed a high degree of residency and significant changes in their habitat use which persisted overnight while the activity ceased. We suggest that provisioning activities can affect species with high level of residency such as the Blacktip Reef Shark. Further research is needed to better understand how these changes behavioural modifications can alter the fitness of this species. It is important to adapt Shark provisioning activities to limit the induced changes in habitat.
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kinship does not predict the structure of a Shark social network
bioRxiv, 2020Co-Authors: Johann Mourier, Serge PlanesAbstract:The role of relatedness in animal societies has received important consideration as a process driving social groups. In the marine world, most studies which have investigated this question have focused on marine mammals such as whales and dolphins. For Sharks, recent studies have demonstrated preferential associations among individuals from which social communities emerge. Assortment patterns have been found according to phenotypic or behavioural traits but the role of genetic relatedness and family structure in shaping the social structure of adult Shark populations has never been investigated. Here, we used a social network analysis crossed with DNA microsatellite genotyping to investigate the role of the genetic relatedness in the social structure of a Blacktip Reef Shark (Carcharhinus melanopterus) population. We found an established social network spatially organized but dynamic through time with different communities merging during the mating periods. Such recombination shows the males being more gregarious. Kinship was not a predictor of associations among Sharks both at the dyad or community levels as individuals tended to associate independently and randomly regardless of the genetic relatedness between individuals. The lack of parental care in this species may contribute to the breakdown of family links in the population early in life, thereby preventing the formation of kin-based social networks.
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Microsatellite Analyses of Blacktip Reef Sharks (Carcharhinus melanopterus) in a Fragmented Environment Show Structured Clusters
2016Co-Authors: Thomas Vignaud, Johann Mourier, Eric Clua, Jeffrey Maynard, Serge PlanesAbstract:The population dynamics of Shark species are generally poorly described because highly mobile marine life is challenging to investigate. Here we investigate the genetic population structure of the Blacktip Reef Shark (Carcharhinus melanopterus) in French Polynesia. Five demes were sampled from five islands with different inter-island distances (50–1500 km). Whether dispersal occurs between islands frequently enough to prevent moderate genetic structure is unknown. We used 11 microsatellites loci from 165 individuals and a strong genetic structure was found among demes with both F-statistics and Bayesian approaches. This differentiation is correlated with the geographic distance between islands. It is likely that the genetic structure seen is the result of all or some combination of the following: low gene flow, time since divergence, small effective population sizes, and the standard issues with the extent to which mutation models actually fit reality. We suggest low levels of gene flow as at least a partial explanation of the level of genetic structure seen among the sampled Blacktip demes. This explanation is consistent with the ecological traits of Blacktip Reef Sharks, and that the suitable habitat for Blacktips in French Polynesia is highly fragmented. Evidence for spatial genetic structure of the Blacktip demes we studied highlights that similar species may have populations with as yet undetected or underestimated structure. Shark biology and the market for their fins make them highly vulnerable and many species are in rapid decline. Our results add weight to th
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microsatellite analyses of Blacktip Reef Sharks carcharhinus melanopterus in a fragmented environment show structured clusters
PLOS ONE, 2013Co-Authors: Thomas Vignaud, Johann Mourier, Eric Clua, Jeffrey Maynard, Serge PlanesAbstract:The population dynamics of Shark species are generally poorly described because highly mobile marine life is challenging to investigate. Here we investigate the genetic population structure of the Blacktip Reef Shark (Carcharhinus melanopterus) in French Polynesia. Five demes were sampled from five islands with different inter-island distances (50–1500 km). Whether dispersal occurs between islands frequently enough to prevent moderate genetic structure is unknown. We used 11 microsatellites loci from 165 individuals and a strong genetic structure was found among demes with both F-statistics and Bayesian approaches. This differentiation is correlated with the geographic distance between islands. It is likely that the genetic structure seen is the result of all or some combination of the following: low gene flow, time since divergence, small effective population sizes, and the standard issues with the extent to which mutation models actually fit reality. We suggest low levels of gene flow as at least a partial explanation of the level of genetic structure seen among the sampled Blacktip demes. This explanation is consistent with the ecological traits of Blacktip Reef Sharks, and that the suitable habitat for Blacktips in French Polynesia is highly fragmented. Evidence for spatial genetic structure of the Blacktip demes we studied highlights that similar species may have populations with as yet undetected or underestimated structure. Shark biology and the market for their fins make them highly vulnerable and many species are in rapid decline. Our results add weight to the case that total bans on Shark fishing are a better conservation approach for Sharks than marine protected area networks.
Joachim Claudet - One of the best experts on this subject based on the ideXlab platform.
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human induced shifts in habitat use and behaviour of a marine predator the effects of bait provisioning in the Blacktip Reef Shark
Animal Conservation, 2020Co-Authors: Johann Mourier, Joachim Claudet, Serge PlanesAbstract:While the negative effects of consumptive pressures on marine predators are well established, the effects of increasing non‐consumptive activities such as wildlife tourism are still understudied. As such, the long‐term effects of the provision of bait on Shark behaviour are still unclear. Here, we assessed the effects of provisioning using a Control‐Impact design on the spatial use and level of residency of the Blacktip Reef Shark Carcharhinus melanopterus over a 2‐year period. We used effect sizes to model the relative changes in residency between provisioning and non‐provisioning sites. Sharks showed a high degree of residency and significant changes in their habitat use which persisted overnight while the activity ceased. We suggest that provisioning activities can affect species with high level of residency such as the Blacktip Reef Shark. Further research is needed to better understand how these behavioural modifications can alter the fitness of this species. It is important to adapt Shark provisioning activities to limit the induced changes in habitat use.
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human induced shifts in habitat use and behaviour of a marine predator the effects of bait provisioning in the Blacktip Reef Shark
Animal Conservation, 2020Co-Authors: Johann Mourier, Joachim Claudet, Serge PlanesAbstract:While the negative effects of consumptive pressures on marine predators are well established, the effects of increasing non-consumptive activities wildlife tourism are still understudied. As such, the long-term effects of the provision of bait on Shark behaviour are still unclear. Here, we assessed the effects of provisioning using a Control-Impact design on the spatial use and level of residency of the Blacktip Reef Shark (Carcharhinus melanopterus) over a two-year period. We used effect sizes to model the differences relative changes in residency between provisioning and non-provisioning sites. Sharks showed a high degree of residency and significant changes in their habitat use which persisted overnight while the activity ceased. We suggest that provisioning activities can affect species with high level of residency such as the Blacktip Reef Shark. Further research is needed to better understand how these changes behavioural modifications can alter the fitness of this species. It is important to adapt Shark provisioning activities to limit the induced changes in habitat.
Colin A Simpfendorfer - One of the best experts on this subject based on the ideXlab platform.
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thermal tolerance and hypoxia tolerance are associated in Blacktip Reef Shark carcharhinus melanopterus neonates
The Journal of Experimental Biology, 2020Co-Authors: Serge Planes, Ian A Bouyoucos, Phillip R Morrison, Ornella C Weideli, Eva Jacquesson, Colin A Simpfendorfer, Colin J Brauner, Jodie L RummerAbstract:ABSTRACT Thermal dependence of growth and metabolism can influence thermal preference and tolerance in marine ectotherms, including threatened and data-deficient species. Here, we quantified the thermal dependence of physiological performance in neonates of a tropical Shark species (Blacktip Reef Shark, Carcharhinus melanopterus) from shallow, nearshore habitats. We measured minimum and maximum oxygen uptake rates (ṀO2), calculated aerobic scope, excess post-exercise oxygen consumption and recovery from exercise, and measured critical thermal maxima (CTmax), thermal safety margins, hypoxia tolerance, specific growth rates, body condition and food conversion efficiencies at two ecologically relevant acclimation temperatures (28 and 31°C). Owing to high post-exercise mortality, a third acclimation temperature (33°C) was not investigated further. Acclimation temperature did not affect ṀO2 or growth, but CTmax and hypoxia tolerance were greatest at 31°C and positively associated. We also quantified in vitro temperature (25, 30 and 35°C) and pH effects on haemoglobin–oxygen (Hb–O2) affinity of wild-caught, non-acclimated Sharks. As expected, Hb–O2 affinity decreased with increasing temperatures, but pH effects observed at 30°C were absent at 25 and 35°C. Finally, we logged body temperatures of free-ranging Sharks and determined that C. melanopterus neonates avoided 31°C in situ. We conclude that C. melanopterus neonates demonstrate minimal thermal dependence of whole-organism physiological performance across a seasonal temperature range and may use behaviour to avoid unfavourable environmental temperatures. The association between thermal tolerance and hypoxia tolerance suggests a common mechanism warranting further investigation. Future research should explore the consequences of ocean warming, especially in nearshore, tropical species.
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sex based differences in movement and space use of the Blacktip Reef Shark carcharhinus melanopterus
PLOS ONE, 2020Co-Authors: Audrey M Schlaff, Michelle R Heupel, Vinay Udyawer, Colin A SimpfendorferAbstract:Information on the spatial ecology of Reef Sharks is critical to understanding life-history patterns, yet gaps remain in our knowledge of how these species move and occupy space. Previous studies have focused on offshore Reefs and atolls with little information available on the movement and space use of Sharks utilising Reef habitats closer to shore. Cross-shelf differences in physical and biological properties of Reefs can alter regional ecosystem processes resulting in different movement patterns for resident Sharks. Passive acoustic telemetry was used to examine residency, space use and depth use of 40 Blacktip Reef Sharks, Carcharhinus melanopterus, on an inshore Reef in Queensland, Australia, and assess temporal or biological influences. All Sharks showed strong site-attachment to inshore Reefs with residency highest among adult females. Sharks exhibited a sex-based, seasonal pattern in space use where males moved more, occupied more space and explored new areas during the reproductive season, while females utilised the same amount of space throughout the year, but shifted the location of the space used. A positive relationship was also observed between space use and size. There was evidence of seasonal site fidelity and long-distance movement with the coordinated, annual migration of two adult males to the study site during the mating season. Depth use was segregated with some small Sharks occupying shallower depths than adults throughout the day and year, most likely as refuge from predation. Results highlight the importance of inshore Reef habitats to Blacktip Reef Sharks and provide evidence of connectivity with offshore Reefs, at least for adult males.
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population structure and residency patterns of the Blacktip Reef Shark carcharhinus melanopterus in turbid coastal environments
Journal of Fish Biology, 2013Co-Authors: Andrew Chin, Andrew J Tobin, Michelle R Heupel, Colin A SimpfendorferAbstract:This study examined the characteristics of a Blacktip Reef Shark Carcharhinus melanopterus population in turbid coastal habitats through a multi-year fishery-independent sampling and tagrecapture programme. Results revealed a highly structured population comprised almost entirely of juveniles and adult females with individuals between 850 and 1050mm total length effectively absent. Mature males were also rarely encountered with adult sex ratio highly biased towards females (female:male=7:1). Mating scars were observed on adult females between December and April, and parturition was observed from December to March. Regression analysis showed that catch rates were significantly higher during the summer wet season between November and May. Recapture data suggested a highly resident population with a recapture rate of 21% and a mean recapture distance of 0 center dot 8km. In addition, 33% of recaptured animals were captured multiple times, indicating long-term residency. Most recaptures were, however, of adults with few juveniles recaptured. Widespread sampling at the study site and in adjacent areas suggested that the population was highly localized to a specific bay. The bimodal and sex-segregated population structure observed here differs from previous reports for this species, and in combination with reproductive observations, suggests population structuring to facilitate reproductive and recruitment success. These data also highlight the potential ecosystem functions performed by coastal habitats in sustaining C. melanopterus populations.
M B Bennett - One of the best experts on this subject based on the ideXlab platform.
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efferent branchial artery reactivity in the Blacktip Reef Shark carckarhinus melanopterus carcharhinidae elasmobranchii
Comparative Biochemistry and Physiology Part C: Pharmacology Toxicology and Endocrinology, 1996Co-Authors: M B BennettAbstract:Efferent branchial arterial ring preparations from the Blacktip Reef Shark, Carcharhinus melanopterus, were used to investigate the tissue reactivity to a range of pharmacological agents. The arterial responses elicited by adrenaline and noradrenaline were somewhat variable. Isoprenaline, a beta-adrenoceptor agonist, always produced a vasodilatation and phenylephrine, an alpha-adrenoceptor agonist, always produced a vasoconstrictory response. The cholinergic agonists, acetylcholine, methylcholine and carbamylcholine, all constricted these branchial arteries. Atropine could successfully antagonise the effects of acetylcholine; suggesting that muscarinic receptors were being activated. Histamine produced modest increases in tension. Adenosine ADP and ATP all produced bimodel tissue responses, with initial contractions reversing to relaxations at higher concentrations. The arterial responses could not be adequately explained with reference to the accepted mammalian purinoceptor scheme.
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the regulation of branchial blood flow in the Blacktip Reef Shark carcharhinus melanopterus carcharhinidae elasmobranchii
Comparative Biochemistry and Physiology Part A: Physiology, 1995Co-Authors: Lisa K Chopin, M B BennettAbstract:The innervation of the branchial vasculature of the Blacktip Reef Shark, Carcharhinus melanopterus, appears similar to that described for other elasmobranchs. Isolated perfused gill arch preparations were used in a study of vascular responses to branchial nerve stimulation. The pre-addition of 10-5 M concentrations of pancuronium to the perfusate prevented skeletal muscle contractions and significantly reduced (P < 0.001) changes in perfusion pressure in response to nerve stimulation. The adductor muscles received an extensive innervation by nerve fibres ramifying from the gill arch. In pharmacological studies, pancuronium completely antagonized the normal vasoconstrictive response to acetylcholine. At low concentrations, noradrenaline produced a vasoconstriction, but this changed to a vasodilatation at concentrations above 10-5 M. The use of antagonists demonstrated the presence of both α-, and β-adrenoceptors in the branchial vasculature. Anatomical studies failed to show adrenergic nerves in the gills, suggesting a lack of a spinal autonomic ('sympathetic') innervation. Adrenergic regulation of gill blood flow may involve the release of catecholamines into the blood stream from chromaffin tissue stores.