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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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Guzy JC, Falk BG, Smith BJ, Willson JD, Reed RN, Aumen NG, Avery ML, Bartoszek IA, Campbell E, Cherkiss MS, Claunch NM, Currylow AF, Dean T, Dixon J, Engeman R, Funck S, Gibble R, Hengstebeck KC, Humphrey JS, Hunter ME, Josimovich JM, Ketterlin J, Kirkland M, Mazzotti FJ, McCleery R, Miller MA, McCollister M, Parker MR, Pittman SE, Rochford M, Romagosa C, Roybal A, Snow RW, Spencer MM, Waddle JH, Yackel Adams AA, Hart KM. Burmese pythons in Florida: A synthesis of biology, impacts, and management tools. NEOBIOTA 2023. [DOI: 10.3897/neobiota.80.90439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Burmese pythons (Python molurus bivittatus) are native to southeastern Asia, however, there is an established invasive population inhabiting much of southern Florida throughout the Greater Everglades Ecosystem. Pythons have severely impacted native species and ecosystems in Florida and represent one of the most intractable invasive-species management issues across the globe. The difficulty stems from a unique combination of inaccessible habitat and the cryptic and resilient nature of pythons that thrive in the subtropical environment of southern Florida, rendering them extremely challenging to detect. Here we provide a comprehensive review and synthesis of the science relevant to managing invasive Burmese pythons. We describe existing control tools and review challenges to productive research, identifying key knowledge gaps that would improve future research and decision making for python control.
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Leatherman SP. Management of invasive snakes in coastal environments: A baseline assessment of the Burmese python invasion in the Florida Everglades. MARINE POLLUTION BULLETIN 2022; 182:113996. [PMID: 35921734 DOI: 10.1016/j.marpolbul.2022.113996] [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: 06/10/2022] [Revised: 07/22/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
The Florida Everglades is a unique and fragile coastal wetland ecosystem that is undergoing a decades-long, large-scale ecological restoration. This freshwater ecosystem in southern Florida has been stressed by diminishment of freshwater flow and water diversion due to agricultural activities and urbanization. The health of this vast ecosystem is also threatened by the presence of a large number of invasive species, including the Burmese python. These large constrictors were introduced to South Florida through the pet trade; first sightings in Everglades National Park occurred in the 1980s. Pythons are naturally camouflaged in the Everglades, which turns out to be an excellent environment for propagation of these huge predators. This top predator has severely disrupted the food web, consuming mammals, birds and even other reptiles. In this paper, the current population control efforts implemented by various management agencies are assessed. While more paid professional hunters should be retained to join the search and removal efforts, innovative control measures are necessary.
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Affiliation(s)
- Stephen P Leatherman
- Department of Earth & Environment, Florida International University, Miami, FL 33199.
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Brown MK, Haskins DL, Russell AL, Lambert ML, Quick CE, Pilgrim MA, Tuberville TD. Mercury and Radiocesium Accumulation and Associations With Sublethal Endpoints in the Florida Green Watersnake (Nerodia floridana). ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2022; 41:758-770. [PMID: 35112731 DOI: 10.1002/etc.5281] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/28/2021] [Accepted: 12/21/2021] [Indexed: 06/14/2023]
Abstract
Mercury (Hg) and radiocesium (137 Cs) are well-known environmental contaminants with the potential to impact the health of humans and wildlife. Snakes have several characteristics conducive to studying environmental contamination but have rarely been included in the monitoring of polluted sites. We investigated the bioaccumulation of Hg and 137 Cs and associations with sublethal effects (standard metabolic rate [SMR] and hemoparasite infections) in Florida green watersnakes (Nerodia floridana). We captured 78 snakes from three former nuclear cooling reservoirs on the US Department of Energy's Savannah River Site in South Carolina (USA). For captured snakes, we (1) determined whole-body 137 Cs, (2) quantified total Hg (THg) using snake tail clips, (3) conducted hemoparasite counts, and (4) measured the SMR. We used multiple regression models to determine associations among snake body size, capture location, sex, tail THg, whole-body 137 Cs, Hepatozoon spp. prevalence and parasitemia, and SMR. Average whole-body 137 Cs (0.23 ± 0.08 Becquerels [Bq]/g; range: 0.00-1.02 Bq/g) was correlated with snake body size and differed significantly by capture site (Pond B: 0.67 ± 0.05 Bq/g; Par Pond: 0.10 ± 0.02 Bq/g; Pond 2: 0.03 ± 0.02 Bq/g). Tail THg (0.33 ± 0.03 mg/kg dry wt; range: 0.16-2.10 mg/kg) was significantly correlated with snake body size but did not differ by capture site. We found no clear relationship between SMR and contaminant burdens. However, models indicated that the prevalence of Hepatozoon spp. in snakes was inversely related to increasing whole-body 137 Cs burdens. Our results indicate the bioaccumulation of Hg and 137 Cs in N. floridana and further demonstrate the utility of aquatic snakes as bioindicators. Our results also suggest a decrease in Hepatozoon spp. prevalence related to increased burdens of 137 Cs. Although the results are intriguing, further research is needed to understand the dynamics between 137 Cs and Hepatozoon spp. infections in semiaquatic snakes. Environ Toxicol Chem 2022;41:758-770. © 2022 SETAC.
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Affiliation(s)
- Marty Kyle Brown
- Savannah River Ecology Laboratory, University of Georgia, Aiken, South Carolina, USA
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia, USA
| | - David Lee Haskins
- Savannah River Ecology Laboratory, University of Georgia, Aiken, South Carolina, USA
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia, USA
- Interdisciplinary Toxicology Program, University of Georgia, Athens, Georgia, USA
| | - Amelia L Russell
- Savannah River Ecology Laboratory, University of Georgia, Aiken, South Carolina, USA
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia, USA
| | - Michaela L Lambert
- Savannah River Ecology Laboratory, University of Georgia, Aiken, South Carolina, USA
- Department of Forestry and Natural Resources, University of Kentucky, Lexington, Kentucky, USA
| | - Caleigh E Quick
- Savannah River Ecology Laboratory, University of Georgia, Aiken, South Carolina, USA
- College of Environmental Science and Forestry, State University of New York, Syracuse, New York, USA
| | - Melissa A Pilgrim
- Division of Natural Sciences and Engineering, University of South Carolina Upstate, Spartanburg, South Carolina, USA
| | - Tracey D Tuberville
- Savannah River Ecology Laboratory, University of Georgia, Aiken, South Carolina, USA
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Haskins DL, Brown MK, Qin C, Xu X, Pilgrim MA, Tuberville TD. Multi-decadal trends in mercury and methylmercury concentrations in the brown watersnake (Nerodia taxispilota). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 276:116722. [PMID: 33640654 DOI: 10.1016/j.envpol.2021.116722] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/19/2021] [Accepted: 02/08/2021] [Indexed: 06/12/2023]
Abstract
Mercury (Hg) is an environmental contaminant that poses a threat to aquatic systems globally. Temporal evaluations of Hg contamination have increased in recent years, with studies focusing on how anthropogenic activities impact Hg bioavailability in a variety of aquatic systems. While it is common for these studies and ecological risk assessments to evaluate Hg bioaccumulation and effects in wildlife, there is a paucity of information regarding Hg dynamics in reptiles. The goal of this study was to investigate temporal patterns in total mercury (THg) and methylmercury (MeHg) concentrations across a 36-year period, as well as evaluate relationships among and between destructive (kidney, liver, muscle) and non-destructive (blood, tail) tissue types in a common watersnake species. To accomplish this, we measured THg and MeHg concentrations in multiple tissues from brown watersnakes (Nerodia taxispilota) collected from Steel Creek on the Savannah River Site (SRS; Aiken, SC, USA) from two time periods (1983-1986 and 2019). We found significant and positive relationships between tail tips and destructive tissues. In both time periods, THg concentrations varied significantly by tissue type, and destructive tissues exhibited higher but predictable THg values relative to tail tissue. Methylmercury concentrations did not differ among tissues from the 1980s but was significantly higher in muscle compared to other tissues from snakes collected in 2019. Percent MeHg of THg in N. taxispilota tissues mirrored patterns reported in other reptiles, although the range of % MeHg in liver and kidney differed between time periods. Both THg and MeHg concentrations in N. taxispilota declined significantly from the 1980s to 2019, with average values 1.6 to 4-fold lower in contemporary samples. Overall, our data add further evidence to the utility of watersnakes to monitor Hg pollution in aquatic environments and suggest attenuation of this contaminant in watersnakes in our study system.
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Affiliation(s)
- David L Haskins
- Interdisciplinary Toxicology Program, University of Georgia, Athens, GA, 30605, USA; Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30605, USA; Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, 29802, USA.
| | - M Kyle Brown
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30605, USA; Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, 29802, USA
| | - Chongyang Qin
- Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, 29802, USA
| | - Xiaoyu Xu
- Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, 29802, USA
| | - Melissa A Pilgrim
- Division of Natural Sciences and Engineering, University of South Carolina Upstate, Spartanburg, SC, 29303, USA
| | - Tracey D Tuberville
- Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, 29802, USA
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Haskins DL, Brown MK, Bringolf RB, Tuberville TD. Brown watersnakes (Nerodia taxispilota) as bioindicators of mercury contamination in a riverine system. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 755:142545. [PMID: 33038814 DOI: 10.1016/j.scitotenv.2020.142545] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/19/2020] [Accepted: 09/19/2020] [Indexed: 06/11/2023]
Abstract
Mercury (Hg) is a contaminant that enters the environment through natural or anthropogenic means. Ecological risk assessments have examined Hg bioaccumulation and effects in many taxa, but little is known about Hg dynamics in reptiles, or their potential use as bioindicator species for monitoring Hg in aquatic systems. Numerous snake species, like North American watersnakes (Nerodia spp.), are piscivorous and are exposed to Hg through their diet. The purpose of this study was to identify factors associated with Hg accumulation in a common watersnake species and compare Hg concentrations of the snakes to those in fish occupying the same habitats. To this end, we sampled brown watersnakes (Nerodia taxispilota) from the Savannah River, a major river system in the southeastern U.S., and compared N. taxispilota Hg accumulation trends to those of bass (Micropterus salmoides), catfish (Ictalurus and Ameiurus spp.), and panfish (Lepomis and Pomoxis spp.) collected from the same reach. Total Hg (THg) in N. taxispilota tail tips ranged from 0.020 to 0.431 mg/kg (wet weight; mean: 0.104 ± 0.008). Snake tail THg was significantly correlated with blood THg, which ranged from 0.003 to 1.140 mg/kg (0.154 ± 0.019). Snake size and site of capture were significantly associated with tail THg. Snake tail THg increased at sites along and downstream of the area of historic Hg pollution, consistent with fish THg. Snake muscle THg was predicted based on tail THg and ranged from 0.095 to 1.160 (0.352 ± 0.022). To gauge Hg biomagnification in N. taxispilota, we compared predicted snake muscle THg concentrations to THg in fish of consumable size. Average biomagnification factors for THg in N. taxispilota were 3.1 (panfish) and 5.4 (catfish), demonstrating N. taxispilota likely biomagnify Hg through their diet. These results reveal N. taxispilota to be an effective bioindicator species for monitoring Hg in aquatic environments.
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Affiliation(s)
- David L Haskins
- Interdisciplinary Toxicology Program, University of Georgia, Athens, GA 30602, United States of America; Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, United States of America; University of Georgia's Savannah River Ecology Laboratory, Aiken, SC 29802, United States of America.
| | - M Kyle Brown
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, United States of America; University of Georgia's Savannah River Ecology Laboratory, Aiken, SC 29802, United States of America
| | - Robert B Bringolf
- Interdisciplinary Toxicology Program, University of Georgia, Athens, GA 30602, United States of America; Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, United States of America
| | - Tracey D Tuberville
- University of Georgia's Savannah River Ecology Laboratory, Aiken, SC 29802, United States of America
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