ORCID Profile
0000-0001-9019-1717
Current Organisation
Université de Montpellier
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Publisher: Springer Science and Business Media LLC
Date: 05-04-2016
Publisher: Public Library of Science (PLoS)
Date: 31-10-2014
Publisher: Cold Spring Harbor Laboratory
Date: 25-11-2019
DOI: 10.1101/853689
Abstract: Genetic relatedness in animal societies is often a factor that drives the structure of 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 in iduals from which social communities emerge. Assortment patterns have been found according to phenotypic or behavioural traits but the role of genetic relatedness in shaping the social structure of adult shark populations has, to the best our knowledge, 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. Based on data from 156 groups of sharks, we used generalized affiliation indices to isolate social preferences from non-social associations, controlling for the contribution of sex, size, gregariousness, spatial and temporal overlap on social associations, to test for the influence of genetic relatedness on social structure. A double permutation procedure was employed to confirm our results and account for issues arising from potentially elevated type I and type II error rates. Kinship was not a predictor of associations and affiliations among sharks at the dyad or community levels as in iduals tended to associate independently of the genetic relatedness among them. 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.
Publisher: Elsevier BV
Date: 08-2021
Publisher: Public Library of Science (PLoS)
Date: 09-04-2013
Publisher: EDP Sciences
Date: 2015
DOI: 10.1051/ALR/2015006
Publisher: Oxford University Press (OUP)
Date: 17-02-2021
Abstract: Genetic relatedness in animal societies is often a factor that drives the structure of 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 in iduals from which social communities emerge. Assortment patterns have been found according to phenotypic or behavioral traits, but the role of genetic relatedness in shaping the social structure of adult shark populations has, to the best of our knowledge, 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. Based on the data from 156 groups of sharks, we used generalized affiliation indices to isolate social preferences from nonsocial associations, controlling for the contribution of sex, size, gregariousness, spatial, and temporal overlap on social associations, to test for the influence of genetic relatedness on social structure. A double-permutation procedure was employed to confirm our results and account for issues arising from potentially elevated type I and type II error rates. Kinship was not a predictor of associations and affiliations among sharks at the dyad or community levels as in iduals tended to associate independently of the genetic relatedness among them. 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.
Publisher: Wiley
Date: 24-06-2010
DOI: 10.1111/J.1095-8649.2010.02693.X
Abstract: Commercially available enzyme immunoassay (EIA) kits were validated for measuring steroid hormone concentrations in blood plasma from three fish species: the orange clownfish Amphiprion percula, the orangefin anemonefish Amphiprion chrysopterus and the blacktip reef shark Carcharhinus melanopterus. A minimum of 5 microl plasma was required to estimate hormone concentrations with both kits. These EIA kits are a simple method requiring minimal equipment, for measuring hormone profiles under field conditions.
Publisher: Springer Science and Business Media LLC
Date: 28-02-2022
DOI: 10.1038/S42003-022-03138-W
Abstract: Despite our critical dependence on aquatic wildlife, we lack a complete understanding of the drivers of population stability and structure for most fish species. Social network analysis has been increasingly used to investigate animal societies as it explicitly links in idual decision-making to population-level processes and demography. While the study of social structure is of great ecological interest, it is also potentially important for species of economic value or of conservation concern. To date however, there has been little focus on how social processes are likely to influence the conservation of fish populations. Here we identify applications for how a social network approach can help address broad fish conservation themes such as population structure, biological invasions or fisheries management. We discuss the burgeoning opportunities offered and challenges still faced by current technologies to integrate social network approaches within fish conservation.
Publisher: Springer Science and Business Media LLC
Date: 11-01-2016
Publisher: Cold Spring Harbor Laboratory
Date: 04-2019
DOI: 10.1101/595793
Abstract: The emergence of DNA barcoding and metabarcoding opened new ways to study biological ersity, however, the completion of DNA barcode libraries is fundamental for such approaches to succeed. This dataset is a DNA barcode reference library (fragment of Cytochrome Oxydase I gene) for 2,190 specimens representing at least 540 species of shore fishes collected over 10 years at 154 sites across the four volcanic archipelagos of French Polynesia the Austral, Gambier, Marquesas and Society Islands, a 5,000,000 km 2 area. At present, 65% of the known shore fish species of these archipelagoes possess a DNA barcode associated with preserved, photographed, tissue s led and cataloged specimens, and extensive collection locality data. This dataset represents one of the most comprehensive DNA barcoding efforts for a vertebrate fauna to date. Considering the challenges associated with the conservation of coral reef fishes and the difficulties of accurately identifying species using morphological characters, this publicly available library is expected to be helpful for both authorities and academics in various fields.
Publisher: Springer Science and Business Media LLC
Date: 27-02-2020
DOI: 10.1038/S41598-020-60062-X
Abstract: Globally, the frequency of shark bites is rising, resulting in an increasing demand for shark deterrents and measures to lessen the impact of shark bites on humans. Most existing shark protection measures are designed to reduce the probability of a bite, but fabrics that minimise injuries when a shark bite occurs can also be used as mitigation devices. Here, we assessed the ability of the Ocean Guardian Scuba7 and Kevlar material to reduce the likelihood of blacktip reef sharks, Carcharhinus melanopterus , from feeding, and to minimise injuries from shark bites. Sharks were enticed to consume a small piece of local reef fish (bait) placed between the two Scuba7 electrodes with the deterrents randomly being turned on or kept off. In the second experiment, the bait was attached to a small pouch made of either standard neoprene or neoprene with a protective layer of Kevlar around it. The Scuba7 reduced the proportion of baits being taken by 67%, (from 100% during control trials to 33%). Sharks also took more time to take the bait when the device was active (165 ± 20.40 s vs. 38.9 ± 3.35 s), approached at a greater distance (80.98 ± 1.72 cm vs. 38.88 ± 3.20 cm) and made a greater number of approaches per trial (19.38 ± 2.29 vs. 3.62 ± 0.53) than when the Scuba7 was inactive. The sizes of punctures from shark bites were significantly smaller on neoprene with Kevlar compared to standard neoprene (3.64 ± 0.26 mm vs. 5.88 ± 0.29 mm). The number of punctures was also fewer when Kevlar was used (14.92 ± 3.16 vs. 74.1 ± 12.44). Overall, the Ocean Guardian Scuba7 and Kevlar reduced the impact of blacktip reef shark bites. These findings may help consumers make informed decisions when purchasing shark deterring and protective products.
Publisher: Wiley
Date: 08-02-2013
DOI: 10.1111/JFB.12039
Abstract: During a survey of the population of blacktip reef shark Carcharhinus melanopterus in Moorea (French Polynesia) between 2007 and 2011, population structural characteristics were estimated from 268 in iduals. Total length (LT ) ranged from 48 to 139 cm and 48 to 157 cm for males and females, respectively, demonstrating that the average LT of females was larger than that of males. The C. melanopterus population at Moorea showed an apparent spatial sexual segregation with females preferentially frequenting lagoons and males the fore-reefs. Mean growth rate was c. 6 cm year(-1) . Males reached sexual maturity at 111 cm LT . This study reports on the population characteristics of this widespread carcharhinid shark species and makes comparisons with other locations, confirming high geographic variability in the population structure of the species.
Publisher: Wiley
Date: 07-2018
DOI: 10.1111/JFB.13645
Abstract: A novel image analysis-based technique applied to unmanned aerial vehicle (UAV) survey data is described to detect and locate in idual free-ranging sharks within aggregations. The method allows rapid collection of data and quantification of fine-scale swimming and collective patterns of sharks. We demonstrate the usefulness of this technique in a small-scale case study exploring the shoaling tendencies of blacktip reef sharks Carcharhinus melanopterus in a large lagoon within Moorea, French Polynesia. Using our approach, we found that C. melanopterus displayed increased alignment with shoal companions when distributed over a sandflat where they are regularly fed for ecotourism purposes as compared with when they shoaled in a deeper adjacent channel. Our case study highlights the potential of a relatively low-cost method that combines UAV survey data and image analysis to detect differences in shoaling patterns of free-ranging sharks in shallow habitats. This approach offers an alternative to current techniques commonly used in controlled settings that require time-consuming post-processing effort.
Publisher: Wiley
Date: 10-08-2021
DOI: 10.1111/JFB.14853
Abstract: Examining the movement ecology of mesopredators is fundamental to developing an understanding of their biology, ecology and behaviour, as well as the communities and ecosystems they influence. The limited research on the residency and movements of benthic marine mesopredators has primarily used visual tags, which do not allow for the efficient and accurate monitoring of in idual space use. In this study, the authors investigated the residency and movement patterns of Port Jackson sharks Heterodontus portusjacksoni (Meyer 1793) at a breeding aggregation site in Jervis Bay, south‐eastern Australia, using passive acoustic telemetry to further our understanding of the movement ecology of these important mesopredators. Between 2012 and 2014, in iduals were tagged with acoustic transmitters, and their residency and movements within the bay were monitored for up to 4 years. H. portusjacksoni showed strong preferences for particular reefs within and between breeding seasons. Males had significantly higher residency indices at their favoured sites relative to females, suggesting that males may be engaging in territorial behaviour. Conversely, female H. portusjacksoni exhibited higher roaming indices relative to males indicating that females may move between sites to assess males. Finally, H. portusjacksoni showed temporal variation in movements between reefs with in iduals typically visiting more reefs at night relative to the day, dusk and dawn corresponding with their nocturnal habits.
Publisher: MDPI AG
Date: 21-01-2021
Abstract: Over the past decade, drones have become a popular tool for wildlife management and research. Drones have shown significant value for animals that were often difficult or dangerous to study using traditional survey methods. In the past five years drone technology has become commonplace for shark research with their use above, and more recently, below the water helping to minimise knowledge gaps about these cryptic species. Drones have enhanced our understanding of shark behaviour and are critically important tools, not only due to the importance and conservation of the animals in the ecosystem, but to also help minimise dangerous encounters with humans. To provide some guidance for their future use in relation to sharks, this review provides an overview of how drones are currently used with critical context for shark monitoring. We show how drones have been used to fill knowledge gaps around fundamental shark behaviours or movements, social interactions, and predation across multiple species and scenarios. We further detail the advancement in technology across sensors, automation, and artificial intelligence that are improving our abilities in data collection and analysis and opening opportunities for shark-related beach safety. An investigation of the shark-based research potential for underwater drones (ROV/AUV) is also provided. Finally, this review provides baseline observations that have been pioneered for shark research and recommendations for how drones might be used to enhance our knowledge in the future.
Publisher: Springer Science and Business Media LLC
Date: 31-03-2015
Publisher: Springer Science and Business Media LLC
Date: 05-2022
Publisher: MDPI AG
Date: 26-10-2022
DOI: 10.3390/S22218208
Abstract: Recent acoustic telemetry positioning systems are able to reconstruct the positions and trajectories of organisms at a scale of a few centimeters to a few meters. However, they present several logistical constraints including receiver maintenance, calibration procedures and limited access to real-time data. We present here a novel, easy-to-deploy, energy self-sufficient underwater positioning system based on the time difference of arrival (TDOA) algorithm and the Global System for Mobile (GSM) communication technology, capable of locating tagged marine organisms in real time. We provide an illustration of the application of this system with empirical ex les using continuous and coded tags in fish and benthic invertebrates. In situ experimental tests of the operational system demonstrated similar performances to currently available acoustic positioning systems, with a global positioning error of 7.13 ± 5.80 m (mean ± SD) and one-third of the pings can be localized within 278 m of the farthest buoy. Despite some required improvements, this prototype is designed to be autonomous and can be deployed from the surface in various environments (rivers, lakes, and oceans). It was proven to be useful to monitor a wide variety of species (benthic and pelagic) in real time. Its real-time property can be used to rapidly detect system failure, optimize deployment design, or for ecological or conservation applications.
Publisher: Public Library of Science (PLoS)
Date: 22-03-2023
DOI: 10.1371/JOURNAL.PONE.0282837
Abstract: Observers of the Polynesian Shark Observatory (ORP), a citizen science network organized mainly through the Polynesian e centers, collected an unprecedented amount of data from more than 13,916 es spanning 43% of the islands of French Polynesia between July 8, 2011, and April 11, 2018. The objective for this type of data collection, which is not accessible within the standard research context, was to provide a unique dataset, and the opportunity to explore the specific ersity, distribution, seasonality and abundance of many elasmobranch species spread out throughout the territory of French Polynesia. Since the data are based on random citizen observations, the spatial distribution was biased toward the most frequented sites and islands where scuba ing is most developed. Overall, the increase in observed abundance of rays and sharks observed in French Polynesia, and the three most s led islands as well as the high specific ersity recorded for the region, provide first evidence on the effectiveness of the French Polynesia’s Shark Sanctuary, established in 2006. These data, collected randomly by the volunteers, also provide insights into potential movement patterns and site fidelity of some of the more commonly observed species. While no final conclusions can be drawn, it is clear that the network of volunteers that regularly contributes information to the Polynesian Shark Observatory plays a very important role in the delivery of much needed data for conservation and management action, as well as providing perspectives for new directions in research on sharks and rays in French Polynesia.
Publisher: Inter-Research Science Center
Date: 13-09-2010
DOI: 10.3354/MEPS08746
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/MF16122
Abstract: Knowledge of the broad-scale movement patterns of sharks is essential to developing effective management strategies. Currently there is a large bias in studies focusing on species that are either large apex predators or found in tropical to subtropical regions. There is limited knowledge of the movements and migrations of benthic and temperate shark species. The present study used passive acoustic telemetry to investigate the movement patterns of a benthic shark species, the Port Jackson shark (Heterodontus portusjacksoni). In iduals were tagged with acoustic transmitters between 2012 and 2014 and their movements were monitored within Jervis Bay and along the east Australian coastline for up to 4 years. Male and female Port Jackson sharks demonstrated high levels of philopatry to both Jervis Bay and their tagging location across multiple years. Although males and females did not differ in their arrival times, females departed from Jervis Bay later than males. Approximately half the tagged in iduals migrated in a southward direction, with in iduals being detected at Narooma, Bass Strait and Cape Barron Island. This study provides conclusive evidence of bisexual philopatry in a benthic temperate shark species, confirming previous hypotheses, and presents the most detailed migration route for Port Jackson sharks to date.
Publisher: Wiley
Date: 07-11-2012
DOI: 10.1111/MEC.12103
Abstract: Conservation of top predators has been emphasized as essential in an ecosystem due to their role in trophic chain regulation. Optimizing conservation strategies for these endangered marine top predators requires direct estimates of breeding patterns and connectivity as these are essential to understanding the population dynamics. There have been some attempts to investigate breeding patterns of reef sharks from litter reconstruction using molecular analyses. However, direct fine-scale migrations of female sharks for parturition as well as connectivity at a medium scale like between islands remain mostly unknown. We used microsatellite DNA markers and a likelihood-based parentage analysis to determine breeding patterns of female blacktip reef sharks in Moorea (Society Islands, French Polynesia). Most females gave birth at their home island but some migrated to specific nursery areas outside the area they are attached to, sometimes going to another island 50 km away across deep ocean. Our analysis also revealed that females migrated to the same nursery for every birthing event. Many offspring showed a high level of inbreeding indicating an overall reduced population size, restricted movements and dispersal, or specific mating behaviour. Females represent the vectors that transport the genes at nursery grounds, and their fidelity should thus define reproductive units. As females seem to be philopatric, males could be the ones dispersing genes between populations. These results highlight the need to conserve coastal zones where female reef sharks seem to exhibit philopatry during the breeding season.
Publisher: Inter-Research Science Center
Date: 16-12-2010
DOI: 10.3354/MEPS08940
Publisher: Springer Science and Business Media LLC
Date: 03-2023
DOI: 10.1186/S40462-022-00364-Z
Abstract: Acoustic telemetry has helped overcome many of the challenges faced when studying the movement ecology of aquatic species, allowing to obtain unprecedented amounts of data. This has made it into one of the most widely used methods nowadays. Many ways to analyse acoustic telemetry data have been made available and deciding on how to analyse the data requires considering the type of research objectives, relevant properties of the data (e.g., resolution, study design, equipment), habits of the study species, researcher experience, among others. To ease this decision process, here we showcase (1) some of the methods used to estimate pseudo-positions and positions from raw acoustic telemetry data, (2) methods to estimate residency and (3) methods to estimate two-dimensional home and occurrence range using geometric or hull-based methods and density-distribution methods, a network-based approach, and three-dimensional methods. We provide ex les of some of these were tested using a s le of real data. With this we intend to provide the necessary background for the selection of the method(s) that better fit specific research objectives when using acoustic telemetry.
Publisher: Springer Science and Business Media LLC
Date: 04-07-2019
DOI: 10.1038/S41597-019-0123-5
Abstract: The emergence of DNA barcoding and metabarcoding opened new ways to study biological ersity, however, the completion of DNA barcode libraries is fundamental for such approaches to succeed. This dataset is a DNA barcode reference library (fragment of Cytochrome Oxydase I gene) for 2,190 specimens representing at least 540 species of shore fishes collected over 10 years at 154 sites across the four volcanic archipelagos of French Polynesia the Austral, Gambier, Marquesas and Society Islands, a 5,000,000 km 2 area. At present, 65% of the known shore fish species of these archipelagoes possess a DNA barcode associated with preserved, photographed, tissue s led and cataloged specimens, and extensive collection locality data. This dataset represents one of the most comprehensive DNA barcoding efforts for a vertebrate fauna to date. Considering the challenges associated with the conservation of coral reef fishes and the difficulties of accurately identifying species using morphological characters, this publicly available library is expected to be helpful for both authorities and academics in various fields.
Publisher: Springer Science and Business Media LLC
Date: 21-05-2019
Publisher: Wiley
Date: 27-07-2019
DOI: 10.1002/ECE3.5323
Publisher: Wiley
Date: 19-10-2012
DOI: 10.1111/J.1095-8649.2012.03449.X
Abstract: Based on direct observations of free-ranging specimens, the giant manta ray Manta birostris is reported from the Marquesas Islands, the first sighting in French Polynesia. Sightings of its sister species, the reef manta ray Manta alfredi, are also reported at the most easterly location in the Pacific Ocean. Preliminary in idual identification as well as notes on their distribution are also reported.
Publisher: The Royal Society
Date: 03-2022
Abstract: Social foraging, where animals forage in groups, takes many forms but is less studied in marine predators as measuring social associations in the wild is challenging. We used biologging (activity, cameras and telemetry receivers) sensors to measure social associations and simultaneous behaviour, in white sharks ( Carcharodon carcharias ) off Guadalupe Island, Mexico. Animal-borne telemetry receivers revealed that sharks varied in the number of associations they formed and occurred most often when sharks were swimming in straight paths or when they were turning frequently. While many associations were likely random, there was evidence of some stronger associations. Sharks varied in the depths they used and their activity, with some in iduals more active in shallow water while others were more active 200–300 m deep. We propose that white sharks associate with other in iduals so they can inadvertently share information on the location or remains of large prey. However, there may be a wide range of in idual variability in both behaviour and sociality. Biologging now enables social associations of animals to be measured, concurrent with measures of their behaviour, so that social foraging of large marine predators can be quantified in the wild.
Publisher: Frontiers Media SA
Date: 29-08-2023
DOI: 10.3389/FMARS.2023.1234059
Abstract: The occurrence and seasonality of the Critically Endangered great hammerhead shark, Sphyrna mokarran , is data deficient in the Central Pacific region. Using photo-identification and laser-photogrammetry, we describe the seasonal population of great hammerhead sharks in the Tiputa pass (Rangiroa atoll) and Tuheiava pass (Tikehau atoll) in the Tuamotu archipelago of French Polynesia. During the austral summer of 2020 and 2021, we recorded a female-biased aggregation of at least 55 in iduals (54 females 1 unknown sex), representing an unprecedented number of S. mokarran in one study. All measured sharks were likely mature with pre-caudal lengths ranging from 147 cm to 297 cm (n = 35). Videos from citizen scientists recorded over a 15-year period enable us to identify 30 additional in iduals between 2006 and 2019, with strong evidence of sexual segregation during the year. Our findings revealed seasonal residency (n = 32) of up to 6 days/month and for up to 5 months at the study site during the austral summer. We also demonstrated site fidelity with 32 in iduals returning to the same atoll for up to 12 years between the first and last sighting, and with limited evidence of connectivity between the two sites. Our analysis also provides preliminary insight into the environmental factors driving S. mokarran aggregation in the Tiputa pass, suggesting a marked influence of the lunar cycle and of ocellated eagle rays ( Aetobatus ocellatus ) abundance. This study, conducted in situ with non-invasive methods offers a unique opportunity to study a great hammerhead shark population in a near-pristine ecosystem and provides important life-history elements for the Central Pacific region.
Publisher: Elsevier BV
Date: 09-2022
Publisher: Wiley
Date: 10-2020
DOI: 10.1002/BES2.1755
Publisher: Springer Science and Business Media LLC
Date: 13-05-2023
DOI: 10.1038/S41598-023-34446-8
Abstract: A perennial criticism of provisioning ecotourism is that it alters the natural behavior and ecology of the target species by providing an artificial food source. Here we evaluate its impact on the long-term site fidelity patterns of tiger sharks in French Polynesia. We hypothesized that a significant impact of provisioning would lead to (1) increases in in idual site fidelity over time, and (2) an increase in the number of resident in iduals over time. Of 53 in iduals photo-identified and monitored during 500 es over five years, 10 in iduals accounted for 75% of all sightings, whereas 35 sharks were sighted very infrequently. Even the most frequently observed tiger sharks exhibited overall low fidelity at the site and showed no increase in site fidelity over time. Furthermore, the number of tiger sharks sighted during each e did not increase. The observed patterns of tiger shark sightings were best explained by natural movements, including general roaming within home ranges along the coastline and seasonal migrations. Despite the apparent lack of impact of provisioning ecotourism on tiger shark ecology in Tahitian waters, it would be prudent to implement a strict code of conduct during any future provisioning activities to maximize the safety of participants and animals involved.
Publisher: Springer Science and Business Media LLC
Date: 30-10-2012
Publisher: Wiley
Date: 16-07-2021
DOI: 10.1002/AQC.3674
Abstract: Knowledge about spatial and temporal variability in the distribution and abundance of predators is necessary to adapt measures to mitigate human–wildlife interactions. Acoustic telemetry and network analyses were used to investigate the spatial ecology of bull sharks, the species responsible for most shark bites in Reunion Island, one of the world's shark bite hotspots. The west coast of the island was not used uniformly by every in idual, with size predicting the movements of sharks along the coast. Node‐based metrics – closeness, node strength, and cumulated continuous residency times – derived from up to 181 monthly movement networks from 20 in iduals, revealed that smaller sharks ( cm total length) primarily used the south‐west coast while larger in iduals spent most of their time in the northern region with regular visits to multiple areas along the coast. This study provides essential knowledge on bull shark behaviour and central areas used at different periods of the year, which correlates well with the dynamics of observed shark bites. Our approach provides a non‐invasive alternative to help predicting and anticipating human–shark conflicts and avoid shark culling programmes detrimental to the conservation of large predators such as sharks.
Publisher: Springer Science and Business Media LLC
Date: 10-09-2019
Publisher: The Royal Society
Date: 28-03-2018
Abstract: To adapt to their environment, organisms can either directly interact with their surroundings or use social information (i.e. information provided by neighbouring in iduals). Social information relates to the external features of surrounding peers, and little is known about its use by solitary species. Here, we investigated the use of social cues in a solitary marine predator by creating artificial aggregations of free-ranging sicklefin lemon sharks ( Negaprion acutidens ). Using a novel monitoring protocol, we analysed both dominance interactions and tolerance associations between sharks competing for food in relation with the number, the morphology and the behaviour of rivals. Sharks produced more agonistic displays and spent more time around the bait as competitors were more abundant. Moreover, the morphological attributes of competitors had very limited influence on the structure of shark social interactions. Instead, sharks appeared to establish tolerance relationships with competitors according to their in idual behaviour. Furthermore, the more two sharks were observed together at a given study site, the fewer agonistic interactions they exchanged. We discuss these findings as evidence of the use of social cues in a non-gregarious predatory species and suggest directions for future research.
Publisher: Springer Science and Business Media LLC
Date: 22-02-2019
DOI: 10.1007/S00442-019-04357-5
Abstract: Ontogenetic niche shifts are widespread. However, in idual differences in size at birth, morphology, sex, and personalities can cause variability in behavior. As such, inherent inter-in idual differences within populations may lead to context-dependent changes in behavior with animal body size, which is of concern for understanding population dynamics and optimizing ecological monitoring. Using stable carbon and nitrogen isotope values from concurrently s led tissues, we quantified the direction and magnitude of intraspecific variation in trophic shifts among three shark species, and how these changed with body size: spurdogs (Squalus spp.) in deep-sea habitats off La Réunion, bull sharks (Carcharhinus leucas) in estuarine habitats of the Florida Everglades, and blacktip reef sharks (Carcharhinus melanopterus) in coral reef ecosystems of Moorea, French Polynesia. Intraspecific variation in trophic shifts was limited among spurdogs, and decreased with body size, while bull sharks exhibited greater in idual differences in trophic shifts, but also decreased in variability through ontogeny. In contrast, blacktip reef sharks exhibited increased intraspecific variation in trophic interactions with body size. Variability in trophic interactions and ontogenetic shifts are known to be associated with changes in energetic requirements, but can vary with ecological context. Our results suggest that environmental stability may affect variability within populations, and ecosystems with greater spatial and/or temporal variability in environmental conditions, and those with more erse food webs may facilitate greater in idual differences in trophic interactions, and thus ontogenetic trophic shifts. In light of concerns over environmental disturbance, elucidating the contexts that promote or d en phenotypic variability is invaluable for predicting population- and community-level responses to environmental changes.
Publisher: Wiley
Date: 30-10-2021
DOI: 10.1111/ETH.13246
Abstract: The tourism activities linked to artificial provisioning of blacktip reef sharks ( Carcharhinus melanopterus ) and pink whiprays ( Pateobatis fai ) on a specific site in French Polynesia were suddenly and completely stopped due to a COVID‐19 lockdown that lasted 6 weeks from March 20 until April 30, 2020. Using both drone footage and underwater counting, we were able to track the abundance of those two species before, during, and after reopening and thus investigate the impact of provisioning on wild shark populations. The absence of any stimulus during this long period resulted in almost total desertion of the site by the elasmobranchs. However, 1 day prior to reopening, some in iduals of both species positively reacted to the single acoustic stimulus of an engine boat, showing the resilience of conditioning, and some elasmobranchs reacted to acoustic and olfactive stimuli linked to the provisioning practice from the first day after reopening. During the first 2 weeks after reopening, the abundance of both species remained at reduced levels comparable to those observed between 2008 and 2010 for sharks i.e., around 9 animals in the presence of local tourists. Pre‐lockdown abundance levels, reaching approximatively 15 in iduals for sharks and 10 for rays, were considered restored 1 and 2 months after reopening for blacktip reef sharks and pink whiprays, respectively. These findings improve our capacity to better understand the potential effects of artificial provisioning tourism on the abundance of elasmobranchs by showing that conditioning is resilient for several weeks, suggesting that intermittent interruption of elasmobranchs feeding would not really help to decrease its impact on animal welfare.
Publisher: The Royal Society
Date: 09-2017
DOI: 10.1098/RSOS.170485
Abstract: Accurately estimating contacts between animals can be critical in ecological studies such as examining social structure, predator–prey interactions or transmission of information and disease. While biotelemetry has been used successfully for such studies in terrestrial systems, it is still under development in the aquatic environment. Acoustic telemetry represents an attractive tool to investigate spatio-temporal behaviour of marine fish and has recently been suggested for monitoring underwater animal interactions. To evaluate the effectiveness of acoustic telemetry in recording interin idual contacts, we compared co-occurrence matrices deduced from three types of acoustic receivers varying in detection range in a benthic shark species. Our results demonstrate that (i) associations produced by acoustic receivers with a large detection range (i.e. Vemco VR2W) were significantly different from those produced by receivers with smaller ranges (i.e. Sonotronics miniSUR receivers and proximity loggers) and (ii) the position of in iduals within their network, or centrality, also differed. These findings suggest that acoustic receivers with a large detection range may not be the best option to represent true social networks in the case of a benthic marine animal. While acoustic receivers are increasingly used by marine ecologists, we recommend users first evaluate the influence of detection range to depict accurate in idual interactions before using these receivers for social or predator–prey studies. We also advocate for combining multiple receiver types depending on the ecological question being asked and the development of multi-sensor tags or testing of new automated proximity loggers, such as the Encounternet system, to improve the precision and accuracy of social and predator–prey interaction studies.
Publisher: Inter-Research Science Center
Date: 24-11-2016
DOI: 10.3354/MEPS11945
Publisher: Springer Science and Business Media LLC
Date: 10-2019
Publisher: No publisher found
Date: 2015
DOI: 10.1016/J.MARENVRES.2015.06.004
Abstract: A better understanding of the key ecological processes of marine organisms is fundamental to improving design and effective implementation of marine protected areas (MPAs) and marine bio ersity. The movement behavior of coral reef fish is a complex mechanism that is highly linked to species life-history traits, predation risk and food resources. We used passive acoustic telemetry to study monthly, daily and hourly movement patterns and space use in two species, Schoolmaster snapper (Lutjanus apodus) and Stoplight parrotfish (Sparisoma viride). We investigated the spatial overlap between the two species and compared intra-specific spatial overlap between day and night. Presence-absence models showed different diel presence and habitat use patterns between the two species. We constructed a spatial network of the movement patterns, which showed that for both species when fish were detected by the array of receivers most movements were made around the coral reef habitat while occasionally moving to silt habitats. Our results show that most in iduals made predictable daily crepuscular migrations between different locations and habitat types, although in idual behavioral changes were observed for some in iduals across time. Our study also highlights the necessity to consider multiple species during MPA implementation and to take into account the specific biological and ecological traits of each species. The low number of fish detected within the receiver array, as well as the intraspecific variability observed in this study, highlight the need to compare results across species and in iduals to be used for MPA management.
Publisher: Springer Science and Business Media LLC
Date: 17-11-2020
DOI: 10.1186/S40317-020-00222-Y
Abstract: Understanding movement patterns of a species is vital for optimising conservation and management strategies. This information is often difficult to obtain in the marine realm for species that regularly occur at depth. The common sawshark ( Pristiophorus cirratus ) is a small, benthic-associated elasmobranch species that occurs from shallow to deep-sea environments. No information is known regarding its movement ecology. Despite this, P. cirrata are still regularly landed as nontargeted catch in the south eastern Australian fisheries. Three in iduals were tagged with pop-up satellite archival tags (PSATs) off the coast of Tasmania, Australia, to test the viability of satellite tagging on these small elasmobranchs and to provide novel insights into their movement. Tags were successfully retained for up to 3 weeks, but movement differed on an in idual basis. All three in iduals displayed a post-release response to tagging and limited vertical movement was observed for up to 5–7 days post-tagging. Temperature loggers on the tags suggest the animals were not stationary but moved horizontally during this time, presumably in a flight response. After this response, continuous wavelet transformations identified diel vertical movements in one in idual at cyclical intervals of 12- and 24-hour periods however, two others did not display as clear a pattern. Temperature was not significantly correlated with movement in the study period. The deepest depths recorded during the deployments for all in iduals was approximately 120 m and the shallowest was 5 m. This study demonstrates that sawsharks can be successfully tagged by pop-up satellite archival tags. The data presented here show that sawsharks regularly move both horizontally and vertically in the water column, which was an unexpected result for this small benthic species. Additional research aimed at resolving the trophic ecology will help identify the drivers of these movements and help to better define the ecological, behavioural and physiological roles of these sharks in their ecosystems. These data describe a substantial ability to move in the common sawshark that was previously unknown and provides the first account of movement ecology on the family of sawsharks: Pristiophoridae.
Publisher: Oxford University Press (OUP)
Date: 2015
Publisher: Cold Spring Harbor Laboratory
Date: 29-08-2019
DOI: 10.1101/749085
Abstract: Animal movement patterns are increasingly analysed as spatial networks. Currently, structures of complex movements are typically represented as a single-layer (or monoplex) network. However, aggregating in idual movements, to generate population-level inferences, considerably reduces information on how in idual or species variability influences spatial connectivity and thus identifying the mechanisms driving network structure remains difficult. Here, we propose incorporating the recent conceptual advances in multilayer network analyses with the existing movement network approach to improve our understanding of the complex interaction between spatial and/or social drivers of animal movement patterns. Specifically, we explore the application and interpretation of this framework using an empirical ex le of shark movement data gathered using passive remote sensors in a coral reef ecosystem. We first show how aggregating in idual movement networks can lead to the loss of information, potentially misleading our interpretation of movement patterns. We then apply multilayer network analyses linking in idual movement networks (i.e. layers) to the probabilities of social contact between in iduals (i.e. interlayer edges) in order to explore the functional significance of different locations to an animal’s ecology. This approach provides a novel and holistic framework incorporating in idual variability in behaviour and inter-in idual interactions. We discuss how this approach can be used in applied ecology and conservation to better assess the ecological significance of variable space use by mobile animals within a population. Further, we argue that the uptake of multilayer networks will significantly broaden our understanding of long-term ecological and evolutionary processes, particularly in the context of information or disease transfer between in iduals.
Publisher: Elsevier BV
Date: 11-2022
DOI: 10.1016/J.MARENVRES.2022.105712
Abstract: As marine stocks and bio ersity are rapidly declining, the release of hatchery-reared in iduals into the wild is a species conservation measure aiming at replenishing stocks of freshwater, anadromous and marine fish species. The aim of this study is to assess for the first time the post-release exploration behaviours, survival and dispersal in the wild of released hatchery-reared juveniles of D. dentex and S. umbra. For this purpose, twenty fish from each species were tagged with acoustic transmitters and released in a marine no-take zone located in Corsica (France). Most in iduals were considered alive until their last detection (95% of S. umbra and 74% of D. dentex detected in iduals). Fish were detected within the receiver array on average up to 11.3 (± 20.7) and 10.3 (± 10.3) days after being released for juveniles of D. dentex and S.umbra, respectively. Dentex dentex juveniles dispersed mostly southward along the shore whereas S. umbra juveniles tended to disperse along the shore both northward and southward from the acoustic receiver array. Before their rapid dispersion (i.e. within a few days) outside the studied zone, juveniles of both species displayed increasing cumulative MCP areas and increased their vertical niche revealing their gradual coverage and exploration of deeper habitats in the area. The results from our study highlighted that hatchery-reared juveniles of both species did not settle inside the studied area but seemed to start to acclimate to the natural environment. This work is a first step towards the assessment of the viability of restocking for both species.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 19-08-2022
Abstract: Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements.
Publisher: Wiley
Date: 13-10-2014
DOI: 10.1111/MEC.12936
Abstract: For free-swimming marine species like sharks, only population genetics and demographic history analyses can be used to assess population health/status as baseline population numbers are usually unknown. We investigated the population genetics of blacktip reef sharks, Carcharhinus melanopterus one of the most abundant reef-associated sharks and the apex predator of many shallow water reefs of the Indian and Pacific Oceans. Our s ling includes 4 widely separated locations in the Indo-Pacific and 11 islands in French Polynesia with different levels of coastal development. Four-teen microsatellite loci were analysed for s les from all locations and two mitochondrial DNA fragments, the control region and cytochrome b, were examined for 10 locations. For microsatellites, genetic ersity is higher for the locations in the large open systems of the Red Sea and Australia than for the fragmented habitat of the smaller islands of French Polynesia. Strong significant structure was found for distant locations with FST values as high as ~0.3, and a smaller but still significant structure is found within French Polynesia. Both mitochondrial genes show only a few mutations across the sequences with a dominant shared haplotype in French Polynesia and New Caledonia suggesting a common lineage different to that of East Australia. Demographic history analyses indicate population expansions in the Red Sea and Australia that may coincide with sea level changes after climatic events. Expansions and flat signals are indicated for French Polynesia as well as a significant recent bottleneck for Moorea, the most human-impacted lagoon of the locations in French Polynesia.
Publisher: Wiley
Date: 13-06-2021
Abstract: An animal's energy landscape considers the power requirements associated with residing in or moving through habitats. Within marine environments, these landscapes can be dynamic as water currents will influence animal power requirements and can change rapidly over diel and tidal cycles. In channels and along slopes with strong currents, updraft zones may reduce energy expenditure of negatively buoyant fishes that are also obligate swimmers. Despite marine predators often residing within high‐current area, no study has investigated the potential role of the energetic landscape in driving such habitat selectivity. Over 500 grey reef sharks Carcharhinus amblyrhynchos reside in the southern channel of Fakarava Atoll, French Polynesia. We used er observations, acoustic telemetry and biologging to show that sharks use regions of predicted updrafts and switch their core area of space use based on tidal state (incoming versus outgoing). During incoming tides, sharks form tight groups and display shuttling behaviour (moving to the front of the group and letting the current move them to the back) to maintain themselves in these potential updraft zones. During outgoing tides, group dispersion increases, swimming depths decrease and shuttling behaviours cease. These changes are likely due to shifts in the nature and location of the updraft zones, as well as turbulence during outgoing tides. Using a biomechanical model, we estimate that routine metabolic rates for sharks may be reduced by 10%–15% when in updraft zones. Grey reef sharks save energy using predicted updraft zones in channels and ‘surfing the slope’. Analogous to birds using wind‐driven updraft zones, negatively buoyant marine animals may use current‐induced updraft zones to reduce energy expenditure. Updrafts should be incorporated into dynamic energy landscapes and may partially explain the distribution, behaviour and potentially abundance of marine predators.
Publisher: The Royal Society
Date: 03-2017
Abstract: In iduals can play different roles in maintaining connectivity and social cohesion in animal populations and thereby influence population robustness to perturbations. We performed a social network analysis in a reef shark population to assess the vulnerability of the global network to node removal under different scenarios. We found that the network was generally robust to the removal of nodes with high centrality. The network appeared also highly robust to experimental fishing. In idual shark catchability decreased as a function of experience, as revealed by comparing capture frequency and site presence. Altogether, these features suggest that in iduals learnt to avoid capture, which ultimately increased network robustness to experimental catch-and-release. Our results also suggest that some caution must be taken when using capture–recapture models often used to assess population size as assumptions (such as equal probabilities of capture and recapture) may be violated by in idual learning to escape recapture.
Publisher: Pensoft Publishers
Date: 04-10-2015
DOI: 10.15560/11.5.1758
Abstract: Expedition Pakaihi I Te Moana was conducted in 2011 to the Marquesas Islands, lying between 07°50ʹ S and 10°35ʹ S latitude and 138°25ʹ W and 140°50ʹ W longitude. The expedition combined extensive col-lections and visual censuses of the shore fish fauna. A total of 74 species are added as new records for the Marquesas Islands the coastal fish fauna of the Marquesas Islands is increased from 415 to 495 species and the number of endemic species is increased from 48 to 68 species. This increases the per-centage of species-level endemism for the Marquesas Islands to 13.7%, ranking as the third highest region of endemism for coral reef fishes in the Indo-Pacific. Only two other peripheral regions, the Hawai’ian Islands and Easter Island, have higher values.
Publisher: Springer Science and Business Media LLC
Date: 04-07-2020
Publisher: Elsevier BV
Date: 08-2016
DOI: 10.1016/J.CUB.2016.05.058
Abstract: The extent of the global human footprint [1] limits our understanding of what is natural in the marine environment. Remote, near-pristine areas provide some baseline expectations for biomass [2, 3] and suggest that predators dominate, producing an inverted biomass pyramid. The southern pass of Fakarava atoll-a biosphere reserve in French Polynesia-hosts an average of 600 reef sharks, two to three times the biomass per hectare documented for any other reef shark aggregations [4]. This huge biomass of predators makes the trophic pyramid inverted. Bioenergetics models indicate that the sharks require ∼90 tons of fish per year, whereas the total fish production in the pass is ∼17 tons per year. Energetic theory shows that such trophic structure is maintained through subsidies [5-9], and empirical evidence suggests that sharks must engage in wide-ranging foraging excursions to meet energy needs [9, 10]. We used underwater surveys and acoustic telemetry to assess shark residency in the pass and feeding behavior and used bioenergetics models to understand energy flow. Contrary to previous findings, our results highlight that sharks may overcome low local energy availability by feeding on fish spawning aggregations, which concentrate energy from other local trophic pyramids. Fish spawning aggregations are known to be targeted by sharks, but they were previously believed to play a minor role representing occasional opportunistic supplements. This research demonstrates that fish spawning aggregations can play a significant role in the maintenance of local inverted pyramids in pristine marine areas. Conservation of fish spawning aggregations can help conserve shark populations, especially if combined with shark fishing bans.
Publisher: Public Library of Science (PLoS)
Date: 13-08-2013
Publisher: Elsevier BV
Date: 02-2012
Publisher: Elsevier BV
Date: 04-2015
Publisher: Elsevier BV
Date: 06-2017
DOI: 10.1016/J.MARENVRES.2017.03.010
Abstract: Food web structure is shaped by interactions within and across trophic levels. As such, understanding how the presence and absence of predators, prey, and competitors affect species foraging patterns is important for predicting the consequences of changes in species abundances, distributions, and behaviors. Here, we used plasma δ
Publisher: Frontiers Media SA
Date: 28-02-2022
Publisher: Elsevier BV
Date: 10-2019
Publisher: Springer Science and Business Media LLC
Date: 20-09-2019
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/MF10163
Abstract: Most arguments invoked so far by the scientific community in favour of shark conservation rely on the ecological importance of sharks, and have little impact on management policies. During a 57-month study, we were able to in idually recognise 39 sicklefin lemon sharks that support a shark-feeding ecotourism activity in Moorea Island, French Polynesia. We calculated the direct global revenue generated by the provisioning site, based on the expenses of local and international ers. The total yearly revenue was around USD5.4 million and the 13 sharks most often observed at the site had an average contribution each of around USD316 699. Any one of these sharks represents a potential contribution of USD2.64 million during its life span. We argue that publicising economic values per in idual will be more effective than general declarations about their ecological importance for convincing policy makers and fishers that a live shark is more valuable than a dead shark for the local economy. Studies monitoring the potential negative ecological effects of long-term feeding of sharks should, however, be conducted to ensure these are also considered. Besides declarations about the non-consumptive direct-use value of sharks, as promoted by ecotourism, the calculation of their other economic values should also benefit shark conservation.
Publisher: Elsevier BV
Date: 02-2020
Publisher: Springer Science and Business Media LLC
Date: 08-06-2020
Publisher: Wiley
Date: 09-08-2020
DOI: 10.1111/ACV.12630
Publisher: Inter-Research Science Center
Date: 28-10-2015
DOI: 10.3354/MEPS11492
Publisher: Wiley
Date: 14-07-2020
DOI: 10.1002/ECY.3117
Publisher: Wiley
Date: 2023
DOI: 10.1002/ECE3.9746
Abstract: Designing appropriate management plans requires knowledge of both the dispersal ability and what has shaped the current distribution of the species under consideration. Here, we investigated the evolutionary history of the endangered gray reef shark ( Carcharhinus amblyrhynchos ) across its range by sequencing thousands of RADseq loci in 173 in iduals in the Indo‐Pacific (IP). We first bring evidence of the occurrence of a range expansion (RE) originating close to the Indo‐Australian Archipelago (IAA) where two stepping‐stone waves (east and westward) colonized almost the entire IP. Coalescent modeling additionally highlighted a homogenous connectivity ( Nm ~ 10 per generation) throughout the range, and isolation by distance model suggested the absence of barriers to dispersal despite the affinity of C. amblyrhynchos to coral reefs. This coincides with long‐distance swims previously recorded, suggesting that the strong genetic structure at the IP scale ( F ST ~ 0.56 between its ends) is the consequence of its broad current distribution and organization in a large number of demes. Our results strongly suggest that management plans for the gray reef shark should be designed on a range‐wide rather than a local scale due to its continuous genetic structure. We further contrasted these results with those obtained previously for the sympatric but strictly lagoon‐associated Carcharhinus melanopterus , known for its restricted dispersal ability. Carcharhinus melanopterus exhibits a similar RE dynamic but is characterized by a stronger genetic structure and a nonhomogeneous connectivity largely dependent on local coral reefs availability. This sheds new light on shark evolution, emphasizing the roles of IAA as source of bio ersity and of life‐history traits in shaping the extent of genetic structure and ersity.
Publisher: Oxford University Press (OUP)
Date: 07-03-2018
Location: France
No related grants have been discovered for Johann Mourier.