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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, Mangione R, Caut S, Bustamante P. Mercury biomagnification in the food web of Agami Pond, Kaw-Roura Nature Reserve, French Guiana. Heliyon 2024; 10:e28859. [PMID: 38596056 PMCID: PMC11002669 DOI: 10.1016/j.heliyon.2024.e28859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 03/26/2024] [Accepted: 03/26/2024] [Indexed: 04/11/2024] Open
Abstract
Freshwater ecosystems are among the most important ecosystems worldwide, however, over the last centuries, anthropogenic pressures have had catastrophic effects on them. Mercury (Hg) is one of the main environmental contaminants which globally affect ecosystems and particularly freshwater wildlife. While Hg originates from natural sources, anthropogenic activities such as agriculture, biomass combustion, and gold mining increase its concentrations. Gold mining activities are the main drivers of Hg emission in tropical ecosystems and are responsible for up to 38% of global emissions. Once in its methylated form (MeHg), mercury biomagnifies through the trophic chain and accumulates in top predators. Due to the toxicity of MeHg, long-lived predators are even more subjected to chronic effects as they accumulate Hg over time. In the present study we quantified Hg contamination in two top predators, the Black caiman Melanosuchus niger and the Agami heron Agamia agami, and in their prey in the Kaw-Roura Nature Reserve in French Guiana and evaluated the biomagnification rate in the trophic chain. Our results show that despite a TMF in the range of others in the region (4.38 in our study), top predators of the ecosystem present elevated concentrations of Hg. We have found elevated Hg concentrations in the blood of adult Black caiman (2.10 ± 0.652 μg g-1 dw) and chicks of Agami heron (1.089 ± 0.406 μg g-1 dw). These findings highlight the need to better evaluate the potential impact of Hg in freshwater top predators, especially regarding reprotoxic effects.
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Affiliation(s)
- Jérémy Lemaire
- Department of Behavioral and Cognitive Biology, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria
| | - Rosanna Mangione
- Department of Behavioral and Cognitive Biology, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria
| | - Stéphane Caut
- Consejo Superior de Investigaciones Cientificas (CSIC), Departamento de Etologia y Conservacion de la Biodiversidad, Estacion Biologica de Doñana, C/ Americo Vespucio, s/n (Isla de la Cartuja), E-41092, Sevilla, Spain
- ANIMAVEG Conservation, 58 avenue du Président Salvador Allende, F-94800, Villejuif, France
| | - Paco Bustamante
- Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 rue Olympe de Gouges, 17000, La Rochelle, France
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3
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Brown MK, Haskins DL, Pilgrim MA, Tuberville TD. Mercury bioaccumulation and Hepatozoon spp. infections in two syntopic watersnakes in South Carolina. ECOTOXICOLOGY (LONDON, ENGLAND) 2024; 33:164-176. [PMID: 38329640 DOI: 10.1007/s10646-024-02736-0] [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: 01/25/2024] [Indexed: 02/09/2024]
Abstract
Mercury (Hg) is a ubiquitous environmental contaminant known to bioaccumulate in biota and biomagnify in food webs. Parasites occur in nearly every ecosystem and often interact in complex ways with other stressors that their hosts experience. Hepatozoon spp. are intraerythrocytic parasites common in snakes. The Florida green watersnake (Nerodia floridana) and the banded watersnake (Nerodia fasciata) occur syntopically in certain aquatic habitats in the Southeastern United States. The purpose of this study was to investigate relationships among total mercury (THg) concentrations, body size, species, habitat type and prevalence and parasitemia of Hepatozoon spp. infections in snakes. In the present study, we sampled N. floridana and N. fasciata from former nuclear cooling reservoirs and isolated wetlands of the Savannah River Site in South Carolina. We used snake tail clips to quantify THg and collected blood samples for hemoparasite counts. Our results indicate a significant, positive relationship between THg and snake body size in N. floridana and N. fasciata in both habitats. Average THg was significantly higher for N. fasciata compared to N. floridana in bays (0.22 ± 0.02 and 0.08 ± 0.006 mg/kg, respectively; p < 0.01), but not in reservoirs (0.17 ± 0.02 and 0.17 ± 0.03 mg/kg, respectively; p = 0.29). Sex did not appear to be related to THg concentration or Hepatozoon spp. infections in either species. We found no association between Hg and Hepatozoon spp. prevalence or parasitemia; however, our results suggest that species and habitat type play a role in susceptibility to Hepatozoon spp. infection.
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Affiliation(s)
- M Kyle Brown
- University of Georgia's Savannah River Ecology Laboratory, Aiken, SC, 29802, USA
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA
| | - David Lee Haskins
- University of Georgia's Savannah River Ecology Laboratory, Aiken, SC, 29802, USA.
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA.
- Interdisciplinary Toxicology Program, University of Georgia, Athens, GA, 30602, USA.
- U.S. Geological Survey, Eastern Ecological Science Center at Patuxent Research Refuge, Laurel, MD, 20708, USA.
| | - Melissa A Pilgrim
- University of Georgia's Savannah River Ecology Laboratory, Aiken, SC, 29802, USA
- University of South Carolina Upstate, Spartanburg, SC, 29303, USA
| | - Tracey D Tuberville
- University of Georgia's Savannah River Ecology Laboratory, Aiken, SC, 29802, USA
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA
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Ibañez AE, Mills WF, Bustamante P, Morales LM, Torres DS, D' Astek B, Mariano-Jelicich R, Phillips RA, Montalti D. Deleterious effects of mercury contamination on immunocompetence, liver function and egg volume in an antarctic seabird. CHEMOSPHERE 2024; 346:140630. [PMID: 37939926 DOI: 10.1016/j.chemosphere.2023.140630] [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: 07/03/2023] [Revised: 10/16/2023] [Accepted: 11/04/2023] [Indexed: 11/10/2023]
Abstract
Mercury (Hg) is a globally important pollutant that can negatively impact metabolic, endocrine and immune systems of marine biota. Seabirds are long-lived marine top predators and hence are at risk of bioaccumulating high Hg concentrations from their prey. Here, we measured blood total mercury (THg) concentrations and relationships with physiology and breeding parameters of breeding brown skuas (Stercorarius antarcticus) (n = 49 individuals) at Esperanza/Hope Bay, Antarctic Peninsula. Mean blood THg concentrations were similar in males and females despite the differences in body size and breeding roles, but differed between study years. Immune markers (hematocrit, Immunoglobulin Y [IgY] and albumin) were negatively correlated with blood THg concentrations, which likely indicates a disruptive effect of Hg on immunity. Alanine aminotransferase (GPT) activity, reflecting liver dysfunction, was positively associated with blood THg. Additionally, triacylglycerol and albumin differed between our study years, but did not correlate with Hg levels, and so were more likely to reflect changes in diet and nutritional status rather than Hg contamination. Egg volume correlated negatively with blood THg concentrations. Our study provides new insights into the sublethal effects of Hg contamination on immunity, liver function and breeding parameters in seabirds. In this Antarctic species, exposure to sublethal Hg concentrations reflects the short-term risks which could make individuals more susceptible to environmental stressors, including ongoing climatic changes.
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Affiliation(s)
- Andrés E Ibañez
- Sección Ornitología, Div. Zool. Vert. Museo de la Plata (FCNyM-UNLP-CONICET), La Plata, Buenos Aires, Argentina.
| | - William F Mills
- Department of Geography and Environmental Science, University of Reading, Reading, UK
| | - Paco Bustamante
- Littoral Environnement et Sociétés (LIENSs), UMR 7266, CNRS-La Rochelle Université, 2 rue Olympe de Gouges, 17000, La Rochelle, France
| | - Lara M Morales
- Sección Ornitología, Div. Zool. Vert. Museo de la Plata (FCNyM-UNLP-CONICET), La Plata, Buenos Aires, Argentina
| | - Diego S Torres
- Sección Ornitología, Div. Zool. Vert. Museo de la Plata (FCNyM-UNLP-CONICET), La Plata, Buenos Aires, Argentina
| | - Beatriz D' Astek
- Sección Ornitología, Div. Zool. Vert. Museo de la Plata (FCNyM-UNLP-CONICET), La Plata, Buenos Aires, Argentina
| | - Rocío Mariano-Jelicich
- Instituto de Investigaciones Marinas y Costeras (IIMyC), UNMdP-CONICET, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
| | - Richard A Phillips
- British Antarctic Survey, Natural Environment Research Council, Cambridge, CB3 0ET, UK
| | - Diego Montalti
- Sección Ornitología, Div. Zool. Vert. Museo de la Plata (FCNyM-UNLP-CONICET), La Plata, Buenos Aires, Argentina; Instituto Antártico Argentino, San Martin, Buenos Aires, Argentina
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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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Lazarus M, Sergiel A, Ferenčaković M, Orct T, Kapronczai L, Pađen L, Janz DM, Reljić S, Zwijacz-Kozica T, Zięba F, Selva N, Huber Đ. Stress and reproductive hormones in hair associated with contaminant metal(loid)s of European brown bear (Ursus arctos). CHEMOSPHERE 2023; 325:138354. [PMID: 36907481 DOI: 10.1016/j.chemosphere.2023.138354] [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: 12/30/2022] [Revised: 03/06/2023] [Accepted: 03/07/2023] [Indexed: 06/18/2023]
Abstract
Environmental contaminants like arsenic (As), cadmium (Cd), mercury (Hg) or lead (Pb) may disrupt hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes due to their endocrine toxicity potential. Resulting long-term physiological stress or adverse effects on wildlife reproduction and ontogeny may cause detrimental effects at the individual and population levels. However, data on environmental metal(loid)s' impact on reproductive and stress hormones in wildlife, especially large terrestrial carnivores, are scarce. Hair cortisol, progesterone and testosterone concentrations were quantified and modelled with hair As, Cd, total Hg, Pb, biological, environmental and sampling factors to test for potential effects in free-ranging brown bears (Ursus arctos) from Croatia (N = 46) and Poland (N = 27). Testosterone in males (N = 48) and females (N = 25) showed positive associations with Hg and an interaction between Cd and Pb, but a negative association with interaction between age and Pb. Higher testosterone was found in hair during its growth phase compared to quiescent phase. Body condition index was negatively associated with hair cortisol and positively associated with hair progesterone. Year and conditions of sampling were important for cortisol variation, while maturity stage for progesterone variation (lower concentrations in cubs and yearlings compared to subadult and adult bears). These findings suggest that environmental levels of Cd, Hg and Pb might influence the HPG axis in brown bears. Hair was shown to be a reliable non-invasive sample for investigating hormonal fluctuations in wildlife while addressing individual and sampling specificities.
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Affiliation(s)
- Maja Lazarus
- Institute for Medical Research and Occupational Health, Zagreb, Croatia.
| | - Agnieszka Sergiel
- Institute of Nature Conservation of Polish Academy of Sciences, Kraków, Poland.
| | | | - Tatjana Orct
- Institute for Medical Research and Occupational Health, Zagreb, Croatia.
| | | | - Lana Pađen
- Faculty of Veterinary Medicine, University of Zagreb, Croatia.
| | - David M Janz
- Toxicology Centre, University of Saskatchewan, Saskatoon, Canada; Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Canada.
| | - Slaven Reljić
- Faculty of Veterinary Medicine, University of Zagreb, Croatia.
| | | | | | - Nuria Selva
- Institute of Nature Conservation of Polish Academy of Sciences, Kraków, Poland; Departamento de Ciencias Integradas, Facultad de Ciencias Experimentales, Centro de Estudios Avanzados en Física, Matemáticas y Computación, Universidad de Huelva, Huelva, Spain.
| | - Đuro Huber
- Institute of Nature Conservation of Polish Academy of Sciences, Kraków, Poland; Faculty of Veterinary Medicine, University of Zagreb, Croatia.
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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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Lemaire J, Brischoux F, Marquis O, Mangione R, Caut S, Brault-Favrou M, Churlaud C, Bustamante P. Relationships between stable isotopes and trace element concentrations in the crocodilian community of French Guiana. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 837:155846. [PMID: 35561901 DOI: 10.1016/j.scitotenv.2022.155846] [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: 10/10/2021] [Revised: 04/26/2022] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
Trace elements in the blood of crocodilians and the factors that influence their concentrations are overall poorly documented. However, determination of influencing factors is crucial to assess the relevance of caimans as bioindicators of environmental contamination, and potential toxicological impact of trace elements on these reptiles. In the present study, we determined the concentrations of 14 trace elements (Ag, As, Cd, Cr, Co, Cu, Fe, Hg, Pb, Mn, Ni, Se, V, and Zn) in the blood of four French Guiana caiman species (the Spectacled Caiman Caiman crocodilus [n = 34], the Black Caiman Melanosuchus niger [n = 25], the Dwarf Caiman Paleosuchus palpebrosus [n = 5] and the Smooth-fronted Caiman Paleosuchus trigonatus [n = 20]) from 8 different sites, and further investigated the influence of individual body size and stable isotopes as proxies of foraging habitat and trophic position on trace element concentrations. Trophic position was identified to be an important factor influencing trace element concentrations in the four caiman species and explained interspecific variations. These findings highlight the need to consider trophic ecology when crocodilians are used as bioindicators of trace element contamination in environmental studies.
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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
| | - Oliver Marquis
- Muséum national d'Histoire naturelle, Parc Zoologique de Paris, 53 avenue de Saint Maurice, 75012 Paris, France
| | - Rosanna Mangione
- Division of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Wohlenstrasse 50a, CH-3032 Hinterkappelen, Switzerland
| | - Stéphane Caut
- Consejo Superior de Investigaciones Cientificas (CSIC), Departamento de Etologia y Conservation de La Biodiversidad - Estacion Biologica de Doñana - C/Americo Vespucio, S/n (Isla de La Cartuja), E-41092 Sevilla, Spain; ANIMAVEG Conservation, 58 Avenue Du Président Salvador Allende, F-94800 Villejuif, France
| | - Maud Brault-Favrou
- Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 rue Olympe de Gouges, 17000 La Rochelle, France
| | - Carine Churlaud
- 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
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10
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Romero-Calderón AG, Alvarez-Legorreta T, Rendón von Osten J, González-Jáuregui M, Cedeño-Vázquez JR. Stress responses in captive Crocodylus moreletii associated with metal exposure. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 308:119685. [PMID: 35764186 DOI: 10.1016/j.envpol.2022.119685] [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: 02/28/2022] [Revised: 06/22/2022] [Accepted: 06/23/2022] [Indexed: 06/15/2023]
Abstract
Environmental pollution by metals has repercussions on wildlife health. It is known that some metals can have an influence on the neuroendocrine stress response, and at the same time, metals have pro-oxidant effects that can overwhelm the antioxidant system and cause oxidative stress. This study evaluates the association of metals with neuroendocrine stress activity and biomarkers of oxidative stress in 42 captive female Morelet's crocodiles (Crocodylus moreletii). We measured five metals of ecotoxicological importance (Hg, Cd, Pb, Cu and Zn), and three biomarkers of the oxidative stress response in the liver: glutathione (GSH) and glutathione disulfide (GSSG) as markers for antioxidant system and thiobarbituric acid reactive substances (TBARS) for oxidative damage. We also measured one biomarker of the neuroendocrine response to stress: corticosterone (B) in blood plasma. The mean ± SD concentrations of metals in the liver expressed in μg/g (dw) were: Cd: 0.004 ± 0.003, Hg: 0.014 ± 0.019, Cu: 0.017 ± 0.013, Zn: 0.043 ± 0.035, Pb: 0.16 ± 0.256. The mean ± SD of GSH was 0.42 ± 0.35 nmol/mg protein, the mean ± SD of GSSG was 0.24 ± 0.20 nmol/mg protein, the mean ± SD concentrations of TBARS were 0.36 ± 0.21 nmol/mg protein, and the mean ± SD of B was 393.57 ± 405.14 pg/mL. Hg presented a significant negative relationship with corticosterone. Cd had a negative relationship with both GSH and GSSG; meanwhile, Zn showed a negative relationship with TBARS levels, could be a protective element against hepatic oxidative damage. Finally, B had negative relationship with oxidative damage. The connection found between Hg and the neuroendocrine stress response, as well as the correlations of Cd and Zn with oxidative damage and antioxidant activity should be studied further, given their toxicological importance and implications for the conservation of C. moreletii and other crocodilians.
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Affiliation(s)
- A G Romero-Calderón
- Department of Sustainability Sciences. El Colegio de la Frontera Sur (ECOSUR), Av. Centenario Km 5.5, 77014, Chetumal, Quintana Roo, Mexico.
| | - T Alvarez-Legorreta
- Department of Sustainability Sciences. El Colegio de la Frontera Sur (ECOSUR), Av. Centenario Km 5.5, 77014, Chetumal, Quintana Roo, Mexico.
| | - J Rendón von Osten
- Instituto de Ecología, Pesquería y Oceanografía del Golfo de México (EPOMEX), Campus VI, Av. Héroes de Nacozari 480, Universidad Autónoma de Campeche, 24070, Campeche, Mexico.
| | - M González-Jáuregui
- Centro de Estudios de Desarrollo Sustentable y Aprovechamiento de la Vida Silvestre (CEDESU), Av. Héroes de Nacozari 480, Universidad Autónoma de Campeche, 24070, Campeche, Mexico.
| | - J R Cedeño-Vázquez
- Department of Systematics and Aquatic Ecology. El Colegio de la Frontera Sur (ECOSUR), Av. Centenario Km 5.5, 77014, Chetumal, Quintana Roo, Mexico.
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Belcher SM, Guillette MP, Robb F, Rock KD. Comparative assessment of blood mercury in American alligators (Alligator mississippiensis) from Coastal North Carolina and Florida. ECOTOXICOLOGY (LONDON, ENGLAND) 2022; 31:1137-1146. [PMID: 35918620 PMCID: PMC9463099 DOI: 10.1007/s10646-022-02573-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/18/2022] [Indexed: 06/15/2023]
Abstract
Mercury (Hg) is a widespread and harmful persistent pollutant of aquatic ecosystems. Except for the northern most populations of American alligators (Alligator Mississippiensis) found in North Carolina, the potential adverse health impacts of Hg on ecosystems and humans consuming alligator meat have been studied for over three decades. Now that alligators are being recreationally hunted and consumed across their range, it is especially important to monitor toxic contaminant levels to best understand possible adverse impacts of exposures on alligator populations and human health. In this study, we determined blood Hg concentrations in American alligators from an urbanized site in Wilmington, NC, a nearby site at Lake Waccamaw, NC, and a site on the St Johns River in Florida. Median blood total Hg (tHg) concentrations were particularly high at Lake Waccamaw (526 ng/g, range 152-946 ng/g), resulting in median muscle concentrations (0.48 mg/kg, range 0.13-0.88 mg/kg) well above US EPA screening values for fish consumption. Median concentrations at the Wilmington site (69 ng/g, range 22-336 ng/g) were generally low, and Hg concentrations from the St Johns River site (143 ng/g, range 54-244 ng/g) were comparable to those reported in previous studies. Analysis of relationships between tHg concentrations and a panel of blood chemistry biomarkers found only modest concentration-dependent impact on biomarkers of renal function. The results of this study reveal that local environmental factors greatly impact Hg bioaccumulation in alligators, findings that reaffirm local contaminant biomonitoring in alligator populations will be critical for affective management and determination of guidelines for safe consumption of harvested alligators.
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Affiliation(s)
- Scott M Belcher
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA.
| | - Matthew P Guillette
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA
| | - Frank Robb
- Environmental Education, Awareness, Research, Support & Services, Titusville, FL, USA
| | - Kylie D Rock
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA
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Thirion F, Tellez M, Van Damme R, Bervoets L. Trace element concentrations in caudal scutes from Crocodylus moreletii and Crocodylus acutus in Belize in relation to biological variables and land use. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 231:113164. [PMID: 35007829 DOI: 10.1016/j.ecoenv.2022.113164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 12/16/2021] [Accepted: 01/01/2022] [Indexed: 06/14/2023]
Abstract
Crocodylus moreletii (Morelet's crocodile) and Crocodylus acutus (American crocodile) are generalist, apex predators of subtropical aquatic habitats in Central America. As top predators, crocodiles may be exposed to high levels of micro pollutants, such as trace elements via bioaccumulation that enter the food web as a consequence of human activities. As such, the status of their population can be considered indicative of that of the entire ecosystem - i.e., crocodiles constitute as genuine indicator species. In this study, we report on the concentrations of trace elements found in the caudal scutes of 178 specimens of C. acutus and C. moreletii from Belize. Our objectives were three-fold: (1) to assess variation in trace element concentration between species, sexes, age classes and body index; (2) to identify areas with elevated exposure to trace elements by comparing concentrations in the scutes of crocodiles at various sites in Belize; and (3) to explore links between crocodile trace element load and local land use. All elements tested (Hg, Pb, Cd, As, Cu, Zn, Co) could be detected in at least some scutes. Many of the readings of As and Co were under or close to the detection limit and were not further analyzed. Relatively high Hg concentrations were observed in adults from Chiquibul Forest (median 3.170 µg/g) and Ambergris Caye (0.834 µg/g). Concentrations of Hg and Pb tended to be higher in adult animals than in juveniles, especially in C. acutus. On the other hand, concentrations of Cd, Cu and Zn were higher in juveniles than in subadult adult animals. Concentrations of Cu were higher in C. acutus than in C. moreletii, but otherwise no species-effects were found for the other trace elements. We found a negative correlation between Hg and Zn concentrations; correlations among Cd, Pb, Cu and Zn concentrations tended to be positive. In both juveniles and adults, animals with high concentrations of Zn had lower body-indices (a proxy for physiological condition). None of the other element concentrations correlated with the body-index. Specimens of C. acutus were more often sampled at coastal sites, while C. moreletii sampling points were typically closer to agricultural or forested areas. A canonical correlation analysis revealed a significant association between trace element load and habitat characteristics. Animals sampled inland, near submontane forests, contained higher levels of Hg, while animals sampled near agricultural, urban or lowland habitats tended to have higher concentrations of Cd, Pb, Cu and Zn. This study identifies the most prevalent trace element concentrations impacting Belizean watersheds while highlighting the exposure risk to non-essential trace elements in less-urbanised areas or protected areas.
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Affiliation(s)
- Felix Thirion
- Free University of Brussels, Department of Biology, Pleinlaan 2, 1050 Brussels, Belgium.
| | | | - Raoul Van Damme
- University of Antwerp, Department of Biology, Universiteitsplein 1, 2610 Wilrijk, Belgium.
| | - Lieven Bervoets
- University of Antwerp, Systemic Physiological and Ecotoxicological Research Group (SPHERE), Groenenborgerlaan 171, 2020 Antwerp, Belgium.
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