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Lemaire J, Bustamante P, Shirley MH. Preliminary assessment of blood mercury contamination in four African crocodile species. ENVIRONMENT INTERNATIONAL 2024; 190:108877. [PMID: 38981413 DOI: 10.1016/j.envint.2024.108877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 07/03/2024] [Accepted: 07/04/2024] [Indexed: 07/11/2024]
Abstract
Heavy metal contamination in the environment is an increasingly pervasive threat to the long-term persistence of wildlife. As high trophic level consumers, crocodylians are at substantial risk from bioaccumulation of mercury (Hg). Despite that they are generally well-studied and the focal species of many conservation efforts around the world, little is known about Hg contamination levels in most crocodylians. Here we preliminarily evaluate blood Hg contamination in four African species - Central African slender-snouted crocodile (Mecistops leptorhynchus), African dwarf crocodile (Osteolaemus tetraspis), West African crocodile (Crocodylus suchus), and Nile crocodile (Crocodylus niloticus) - from a diversity of sites and habitats across 5 different countries representing varying degrees of environmental pollution. All of our sampled crocodiles were Hg contaminated and, worryingly, these African crocodiles generally showed the highest levels of Hg contamination of any crocodylian species examined to date. Of most concern was that Hg concentrations were not only highest in M. leptorhynchus, the most threatened amongst our study species, but also in individuals sampled in what are believed to be some of the most remote and pristine natural areas left in Africa - Gabon's national parks. Our results underscore the need to better understand the impact of longstanding petroleum, mining, forestry, and agricultural industries on the entire aquatic food chain throughout much of Africa, including on the threatened species in these habitats and the human populations that depend on them for their subsistence and livelihoods.
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Affiliation(s)
- Jérémy Lemaire
- Department of Behavioral and Cognitive Biology, University of Vienna, Djerassiplatz 1, 1030 Vienna, Austria.
| | - Paco Bustamante
- Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 rue Olympe de Gouges, 17000 La Rochelle, France
| | - Matthew H Shirley
- Project Mecistops, Sarasota, FL, USA; Global Forensics and Justice Center, Florida International University, Miami, FL, USA
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Lemaire J. Using Crocodylians for monitoring mercury in the tropics. ECOTOXICOLOGY (LONDON, ENGLAND) 2023; 32:977-993. [PMID: 37815690 PMCID: PMC10622360 DOI: 10.1007/s10646-023-02703-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/19/2023] [Indexed: 10/11/2023]
Abstract
Mercury contamination is a widespread phenomenon that impacts ecosystems worldwide. Artisanal Small Scale Gold Mining (ASGM) activities are responsible for more than a third of atmospheric Hg emission. Due to Hg toxicity and its broad and elevated prevalence in the environment resulting from ASGM activities in the tropics, its biomonitoring is essential to better understand the availability of its methylmercury (MeHg) form in the environment. The Minamata Convention was ratified with the objective to "protect human health and the environment from anthropogenic emissions and releases of mercury compounds". Biomagnification of MeHg occurs through the trophic food web, where it biomagnifies and bioaccumulates in top predators. To monitor environmental MeHg contamination, studies have evaluated the use of living organisms; however, reptiles are among the least documented vertebrates regarding MeHg exposure. In this review we evaluate the use of crocodylians for Hg biomonitoring in tropical ecosystems. We found that out of the 28 crocodiles species, only 10 have been evaluated regarding Hg contamination. The remaining challenges when using this taxon for Hg biomonitoring are inconsistencies in the applied methodology (e.g., wet versus dry weight, tissues used, quantification method). However, due to their life history traits, crocodylians are particularly relevant for monitoring MeHg contamination in regions where ASGM activities occur. In conclusion and given their ecological and socio-economic importance, crocodylians are at great risk of MeHg contamination and are excellent bioindicators for tropical ecosystems.
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Affiliation(s)
- Jérémy Lemaire
- Department of Behavioral and Cognitive Biology, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria.
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Johnson JM, Smaga CR, Bock SL, Parrott BB. Maternal provisioning interacts with incubation temperature to affect hatchling mercury exposure in an oviparous reptile. Biol Lett 2023; 19:20230097. [PMID: 37554010 PMCID: PMC10410221 DOI: 10.1098/rsbl.2023.0097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 07/25/2023] [Indexed: 08/10/2023] Open
Abstract
The thermal environment experienced by developing embryos can influence the utilization of maternally provisioned resources. Despite being particularly consequential for oviparous ectotherms, these dynamics are largely unexplored within ecotoxicological frameworks. Here, we test if incubation temperature interacts with maternally transferred mercury to affect subsequent body burdens and tissue distributions of mercury in hatchling American alligators (Alligator mississippiensis). Nine clutches of alligator eggs were collected from a mercury-contaminated reservoir and incubated at either female- or male-promoting temperatures. Total mercury (THg) concentration was measured in egg yolk collected during incubation and in a suite of tissues collected from hatchlings. THg concentrations in residual yolk and blood were higher in hatchlings incubated at cooler, female-promoting temperatures compared to the warmer, male-promoting temperatures. THg concentrations in most tissues were positively correlated with THg concentrations in blood and dermis, and egg yolk THg concentration was the best predictor of THg concentration in many resultant tissues. Our results highlight a hereto unknown role of the developmental environment in mediating tissue specific uptake of contaminants in an oviparous reptile.
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Affiliation(s)
- Josiah M. Johnson
- Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, SC 29802, USA
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
| | - Christopher R. Smaga
- Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, SC 29802, USA
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
| | - Samantha L. Bock
- Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, SC 29802, USA
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
| | - Benjamin B. Parrott
- Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, SC 29802, USA
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
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Johnson JM, Bock SL, Smaga CR, Lambert MR, Rainwater TR, Wilkinson PM, Parrott BB. Relationships between maternally-transferred mercury and hatchling development, behavior, and survival in the American alligator (Alligator mississippiensis). THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 870:162010. [PMID: 36739038 DOI: 10.1016/j.scitotenv.2023.162010] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/27/2022] [Accepted: 01/30/2023] [Indexed: 06/18/2023]
Abstract
Mercury is a toxic and pervasive environmental contaminant that can be transferred from mother to offspring during development. Consequences of maternally-transferred mercury have been observed in vertebrate taxa, including reduced clutch viability, reduced offspring size, and behavioral alterations. These sublethal effects have been assumed to decrease survivorship, though this is seldom assessed. Here, we examined how maternally-transferred mercury interacts with incubation temperature to influence reproductive success, offspring behavior, and subsequent survival in the American alligator (Alligator mississippiensis). We collected nine clutches of eggs from a mercury contaminated reservoir on the Savannah River Site, South Carolina, and incubated eggs at either female- or male-promoting temperatures. Clutch-averaged mercury in egg yolk was high relative to other studies in crocodilians and ranged from 0.248 to 0.554 ppm compared to 0.018-0.052 ppm at a site with low levels of mercury contamination; mercury levels in hatchling blood ranged from 0.090 to 0.490 ppm (x¯ = 0.240 ppm, n = 158). We found few, mostly negligible correlations between life history traits and mercury but noted a positive relationship with egg mass, possibly mediated by correlated maternal effects such as resource provisioning. Incubation temperature exerted strong effects on hatchling phenotypes, with warmer, male-promoting temperatures producing larger and bolder hatchlings. Presumptive females, produced from cooler incubation temperatures, spent more time in warm areas during behavior trials. Hatchlings were released 10-15 days post-hatch and surveyed over eight months to assess survival. Survivorship was positively correlated with hatchling size and negatively correlated with proportional time spent in warm areas. Presumptive females had much lower survival, and overall survivorship for the eight-month period was 0.185-0.208, depending on the modelling approach. Our study suggests that, within the range of concentrations we observed, incubation temperature has a stronger effect on offspring behavior and survival than maternally-transferred mercury pollution in American alligators.
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Affiliation(s)
- Josiah M Johnson
- Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, SC 29802, United States; Odum School of Ecology, University of Georgia, Athens, GA 30602, United States.
| | - Samantha L Bock
- Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, SC 29802, United States; Odum School of Ecology, University of Georgia, Athens, GA 30602, United States
| | - Christopher R Smaga
- Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, SC 29802, United States; Odum School of Ecology, University of Georgia, Athens, GA 30602, United States
| | - Max R Lambert
- Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA 94720, United States
| | - Thomas R Rainwater
- Belle W. Baruch Institute of Coastal Ecology and Forest Science, Clemson University, Georgetown, SC 29442, United States; Tom Yawkey Wildlife Center, Georgetown, SC 29440, United States
| | | | - Benjamin B Parrott
- Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, SC 29802, United States; Odum School of Ecology, University of Georgia, Athens, GA 30602, United States
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Zhao Y, Chen J, Wang R, Pu X, Wang D. A review of transgenerational and multigenerational toxicology in the in vivo model animal Caenorhabditis elegans. J Appl Toxicol 2023; 43:122-145. [PMID: 35754092 DOI: 10.1002/jat.4360] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 06/09/2022] [Accepted: 06/24/2022] [Indexed: 11/09/2022]
Abstract
A large number of pollutants existing in the environment can last for a long time, and their potential toxic effects can transfer from parents to their offspring. Thus, it is necessary to investigate the toxicity of environmental pollutants across multigenerations and the underlying mechanisms in organisms. Due to its short life cycle and sensitivity to environmental exposures, Caenorhabditis elegans is an important animal model for toxicity assessment of environmental pollutants across multigenerations. In this review, we introduced the transgenerational and multigenerational toxicity caused by various environmental pollutants in C. elegans. Moreover, we discussed the underlying mechanisms for the observed transgenerational and multigenerational toxicity of environmental contaminants in C. elegans.
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Affiliation(s)
- Yunli Zhao
- Medical School, Southeast University, Nanjing, China.,School of Public Health, Bengbu Medical College, Bengbu, China
| | - Jingya Chen
- School of Public Health, Bengbu Medical College, Bengbu, China
| | - Rui Wang
- School of Public Health, Bengbu Medical College, Bengbu, China
| | - Xiaoxiao Pu
- School of Public Health, Bengbu Medical College, Bengbu, China
| | - Dayong Wang
- Medical School, Southeast University, Nanjing, China
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Humphries M, Benitez-Nelson N, Combrink X. Trace Metal Accumulation in Eggs of Wild Nile Crocodiles (Crocodylus niloticus) from Lake St Lucia, South Africa: Implications for Biomonitoring in a Global Biodiversity Hotspot. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2022; 83:214-225. [PMID: 36171509 DOI: 10.1007/s00244-022-00960-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 09/17/2022] [Indexed: 06/16/2023]
Abstract
Nile crocodiles (Crocodylus niloticus) at Lake St Lucia, South Africa, have some of the highest blood lead (Pb) concentrations ever recorded in wildlife globally. Although exposure to Pb is known to pose major risks to wildlife reproductive success, potential impacts on crocodile reproduction at Lake St Lucia have yet to be examined. In this study, we investigated the accumulation of Pb and other trace metals (Al, V, Cr, Co, Cu, Ni, Zn and Cd) in eggs (n = 20) collected from five wild crocodile nests at Lake St Lucia. All metals analysed in this study were detected in egg contents, although concentrations varied considerably among nests and within clutches. Lead was detected in the contents of all eggs, but only at relatively low concentrations (43 ± 26 ng g-1 dry weight). Although sampling limitations commonly associated with wild population surveys prevent a complete assessment of exposure variability, our findings suggest maternal transfer may not be a significant depuration pathway for Pb and females possibly clear Pb through other mechanisms (e.g. sequestration into claws, bone and osteoderms). Metal concentrations in eggshells and shell membranes were poorly correlated with concentrations measured in egg content and thus do not provide viable non-lethal indicators for monitoring metal exposure in Nile crocodiles. Intra-clutch variability accounted for a considerable proportion of the total variance in egg content metal concentrations, suggesting the "one egg" sampling strategy often applied in reptile studies may not be an effective biomonitoring tool for wild crocodilian populations. Although maternally derived Pb does not appear to present widespread toxicological concern at Lake St Lucia, adverse effects of Pb exposure on other reproductive functions (e.g. spermatogenesis) cannot be discounted and warrant further investigation.
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Affiliation(s)
- Marc Humphries
- School of Chemistry, University of the Witwatersrand, Johannesburg, South Africa.
| | - Noah Benitez-Nelson
- School of Chemistry, University of the Witwatersrand, Johannesburg, South Africa
| | - Xander Combrink
- Department of Nature Conservation, Tshwane University of Technology, Pretoria, South Africa
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Martins MF, Costa PG, Bianchini A. Assessing multigenerational exposure to metals in elasmobranchs: Maternal transfer of contaminants in a yolk-sac viviparous species. MARINE POLLUTION BULLETIN 2022; 175:113364. [PMID: 35093781 DOI: 10.1016/j.marpolbul.2022.113364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/13/2022] [Accepted: 01/16/2022] [Indexed: 06/14/2023]
Abstract
This study aimed to assess the maternal offloading of metals in the Brazilian guitarfishPseudobatos horkelii through determining essential (Cr, Cu, Fe) and non-essential (Cd, Hg, Pb) metal concentrations along two generations of this species: pregnant females and offspring. The maximum transfer capacity (ECER) and offspring/mother ratio were calculated to estimate the extent of offloading, as well as the proportion of contaminants presented in offspring related to the maternal concentrations. Transfer efficiency was element-dependent. Chromium had the highest ECER (99.7%), followed by Hg (67.7%). Other essential metals were less transferred (9.6-35.6%) and Cd and Pb were not detected in uterine content samples. The relationships between maternal length and concentration, as well as transfer capacity were not significant, indicating that females might be continuously exposed, and that offloading might not excrete metals efficiently. On the other hand, embryos are exposed to these elements which could impair embryonic development.
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Affiliation(s)
- Mariana F Martins
- Programa de Pós-Graduação em Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande-FURG, Av. Itália Km 8, 96203-900, Rio Grande, Brazil.
| | - Patrícia G Costa
- Instituto de Ciências Biológicas, Universidade Federal do Rio Grande-FURG, Av. Itália Km 8, 96203-900, Rio Grande, Brazil
| | - Adalto Bianchini
- Instituto de Ciências Biológicas, Universidade Federal do Rio Grande-FURG, Av. Itália Km 8, 96203-900, Rio Grande, Brazil
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Lemaire J, Bustamante P, Mangione R, Marquis O, Churlaud C, Brault-Favrou M, Parenteau C, Brischoux F. Lead, mercury, and selenium alter physiological functions in wild caimans (Caiman crocodilus). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 286:117549. [PMID: 34438486 DOI: 10.1016/j.envpol.2021.117549] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/04/2021] [Accepted: 06/05/2021] [Indexed: 06/13/2023]
Abstract
Environmental contaminants affect ecosystems worldwide and have deleterious effects on biota. Non-essential mercury (Hg) and lead (Pb) concentrations are well documented in some taxa and are described to cause multiple detrimental effects on human and wildlife. Additionally, essential selenium (Se) is known to be toxic at high concentrations but, at lower concentrations, Se can protect organisms against Hg toxicity. Crocodilians are known to bioaccumulate contaminants. However, the effects of these contaminants on physiological processes remain poorly studied. In the present study, we quantified Hg, Pb and Se concentrations in spectacled caimans (Caiman crocodilus) and investigated the effects of these contaminants on several physiological processes linked to osmoregulatory, hepatic, endocrine and renal functions measured through blood parameters in 23 individuals. Mercury was related to disruption of osmoregulation (sodium levels), hepatic function (alkaline phosphatase levels) and endocrine processes (corticosterone levels). Lead was related to disruption of hepatic functions (glucose and alanine aminotransferase levels). Selenium was not related to any parameters, but the Se:Hg molar ratio was positively related to the Na+ and corticosterone concentrations, suggesting a potential protective effect against Hg toxicity. Overall, our results suggest that Hg and Pb alter physiological mechanisms in wild caimans and highlight the need to thoroughly investigate the consequences of trace element contamination in crocodilians.
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Affiliation(s)
- Jérémy Lemaire
- Centre d'Études Biologiques de Chizé (CEBC), UMR 7372 CNRS-La Rochelle Université, 79360 Villiers en Bois, France; Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 rue Olympe de Gouges, 17000 La Rochelle, France.
| | - Paco Bustamante
- Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 rue Olympe de Gouges, 17000 La Rochelle, France; Institut Universitaire de France (IUF), 1 rue Descartes, 75005 Paris, France
| | - Rosanna Mangione
- Division of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Wohlenstrasse 50a, CH-3032, Hinterkappelen, Switzerland
| | - Olivier Marquis
- Sorbonne Université, Muséum National d'Histoire Naturelle, Parc Zoologique de Paris, 53 Avenue de Saint Maurice, 75012 Paris, France
| | - Carine Churlaud
- Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 rue Olympe de Gouges, 17000 La Rochelle, France
| | - Maud Brault-Favrou
- Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 rue Olympe de Gouges, 17000 La Rochelle, France
| | - Charline Parenteau
- Centre d'Études Biologiques de Chizé (CEBC), UMR 7372 CNRS-La Rochelle Université, 79360 Villiers en Bois, France
| | - François Brischoux
- Centre d'Études Biologiques de Chizé (CEBC), UMR 7372 CNRS-La Rochelle Université, 79360 Villiers en Bois, France
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Lemaire J, Brischoux F, Marquis O, Mangione R, Bustamante P. Variation of Total Mercury Concentrations in Different Tissues of Three Neotropical Caimans: Implications for Minimally Invasive Biomonitoring. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2021; 81:15-24. [PMID: 33899129 DOI: 10.1007/s00244-021-00846-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/08/2021] [Indexed: 06/12/2023]
Abstract
Mercury (Hg) is a global environmental contaminant that affects ecosystems. It is known to biomagnify through food webs and to bioaccumulate especially in the tissues of top predators. Large-scale comparisons between taxa and geographic areas are needed to reveal critical trends related to Hg contamination and its deleterious effects on wildlife. Yet, the large variety of tissues (keratinized tissues, internal organs, blood) as well as the variability in the units used to express Hg concentrations (either in wet- or dry-tissue weight) limits straightforward comparisons between studies. In the present study, we assessed the moisture content that could influence the total Hg (THg) concentrations measured in several tissues (claws, scutes, total blood, and red blood cells) of three caiman species. We evaluated the moisture content from the different tissues to provide information on THg concentrations in various matrices. Our results show a difference of THg concentrations between the tissues and intra- and interspecific variations of moisture content, with the highest THg values found in keratinized tissues (scute keratinized layers and claws). For the three species, we found positive relationships between body size and THg concentration in keratinized tissues. In the blood, the relationship between body size and THg concentration was species-dependent. Our results emphasize the need for a standardized evaluation of THg concentration and trace elements quantification based on dry weight analytical procedures. In addition, the use of both blood and keratinized tissues offers the possibility to quantify different time scales of THg exposure by non-lethal sampling.
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Affiliation(s)
- Jérémy Lemaire
- Centre d'Études Biologiques de Chizé (CEBC), UMR 7372 CNRS-La Rochelle Université, 79360, Villiers en Bois, France.
- Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, 17000, La Rochelle, France.
| | - François Brischoux
- Centre d'Études Biologiques de Chizé (CEBC), UMR 7372 CNRS-La Rochelle Université, 79360, Villiers en Bois, France
| | - Olivier Marquis
- Parc Zoologique de Paris, Muséum National d'Histoire Naturelle, 53 Avenue de Saint Maurice, 75012, Paris, France
| | - Rosanna Mangione
- Haus des Meeres Aqua Terra Zoo GmbH, Fritz-Grünbaum Platz 1, 1060, Vienna, Austria
| | - Paco Bustamante
- Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, 17000, La Rochelle, France
- Institut Universitaire de France (IUF), 1 Rue Descartes, 75005, Paris, France
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