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Sánchez-Domene D, da Silva FR, Provete DB, Navarro-Lozano A, Acayaba RD, Montagner CC, Rossa-Feres DDC, López-Iborra GM, Almeida EA. Combined effects of landscape composition and agrochemicals on frog communities amid sugarcane-dominated agroecosystems. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023; 33:e2781. [PMID: 36398791 DOI: 10.1002/eap.2781] [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: 11/09/2021] [Revised: 08/30/2022] [Accepted: 09/09/2022] [Indexed: 06/16/2023]
Abstract
Global demand for crops will continue increasing over the next few decades to cover both food and biofuel needs. This demand will put further pressure to expand arable land and replace natural habitats. However, we are only beginning to understand the combined effects of agrochemicals and land-use change on tropical freshwater biodiversity. In this study, we analyzed how pond-dwelling anuran larvae responded to pond characteristics, landscape composition, and agrochemical contamination in a sugarcane-dominated agroecosystem in Brazil. Then we used an information theoretical approach with generalized linear models to relate species richness and abundance to predictor variables. The variation in tadpole abundance was associated with both agrochemical concentration (e.g., ametryn, diuron, and malathion) and landscape variables (e.g., percentage of forest, percentage of agriculture, and distance to closest forest). The relationship between species abundance and agrochemicals was species-specific. For example, the abundances of Scinax fuscovarius and Physalaemus nattereri were negatively associated with ametryn, and Dendropsophus nanus was negatively associated with tebuthiuron, whereas that of Leptodactylus fuscus was positively associated with malathion. Conversely, species richness was associated with distance to forest fragments and aquatic vegetation heterogeneity, but not agrochemicals. Although we were unable to assign a specific mechanism to the variation in tadpole abundance based on field observations, the lower abundance of three species in ponds with high concentrations of agrochemicals suggest they negatively impact some frog species inhabiting agroecosystems. We recommend conserving ponds near forest fragments, with abundant stratified vegetation, and far from agrochemical runoffs to safeguard more sensitive pond-breeding species.
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Affiliation(s)
- David Sánchez-Domene
- Instituto de Pesquisa em Bioenergia, Universidade Estadual Paulista - UNESP, Rio Claro, Brazil
| | - Fernando R da Silva
- Laboratório de Ecologia Teórica: Integrando Tempo, Biologia e Espaço (LET.IT.BE), Departamento de Ciências Ambientais, Universidade Federal de São Carlos - UFSCAr, Sorocaba, Brazil
| | - Diogo B Provete
- Instituto de Biociências, Universidade Federal de Mato Grosso do Sul, Campo Grande, Brazil
- Gothenburg Global Biodiversity Centre, Göteborg, Sweden
| | - Alba Navarro-Lozano
- Laboratório de Ecologia Teórica, Departamento de Zoologia e Botânica, Universidade Estadual Paulista - UNESP, São José do Rio Preto, Brazil
| | - Raphael D Acayaba
- Laboratório de Química Ambiental, Instituto de Química, Universidade Estadual de Campinas - UNICAMP, Cidade Universitária "Zeferino Vaz", Campinas, Brazil
| | - Cassiana C Montagner
- Laboratório de Química Ambiental, Instituto de Química, Universidade Estadual de Campinas - UNICAMP, Cidade Universitária "Zeferino Vaz", Campinas, Brazil
| | - Denise de C Rossa-Feres
- Laboratório de Ecologia Teórica, Departamento de Zoologia e Botânica, Universidade Estadual Paulista - UNESP, São José do Rio Preto, Brazil
| | - Germán M López-Iborra
- Departamento de Ecologia/IMEM Ramon Margalef, Universidad de Alicante, Campus de San Vicente del Raspeig, Alicante, Spain
| | - Eduardo A Almeida
- Departamento de Ciências Naturais, Universidade Regional de Blumenau, Blumenau, Brazil
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2
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Windle S, McMurry S, Brain R, Maul J, Pickford DB, Wolf J, Belden J. Evaluating a developmental endocrine toxicity assay for Blanchard's cricket frog (Acris blanchardi) in outdoor enclosures. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 767:145444. [PMID: 33636781 DOI: 10.1016/j.scitotenv.2021.145444] [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: 11/20/2020] [Revised: 01/22/2021] [Accepted: 01/23/2021] [Indexed: 06/12/2023]
Abstract
A developmental toxicity testing design was evaluated for larval and post-metamorphic Blanchard's cricket frogs (Acris blanchardi) raised in outdoor enclosures. Larvae were chronically exposed to 17β-estradiol (0.0-2.3 μg/L E2) from free swimming (Gosner stage 26) until metamorphosis. Juvenile frogs were allowed to mature within the enclosures for 60 days to assess effects of larval exposure on development, including body mass, snout-vent length (SVL), sex ratio, gonad size, and gonadal histopathology. Forty-eight percent of the initial 600 animals were recovered at the end of the study. Recovery was not influenced by E2 exposure, but larval losses were negatively impacted by unusually high spring rain events that flooded some larval tanks, and heat-related mortality of late stage larvae during summer. All surviving larvae completed metamorphosis within an average of 47 days. Overall, E2 exposure did not influence sex ratio, or the body mass, SVL, or gonad size of either males or females. Development of testes was not influenced by E2 exposure, but oviduct development in males was 4.5-fold greater in the highest treatment. Oviduct and ovary development in females exposed to the two highest E2 treatments were half that of control females. Although not treatment related and despite ad-lib feeding, variation in terminal body mass and SVL within enclosures was pronounced, with minimum - maximum differences ranging from 207 to 1442 mg for body mass and 1 mm to 15 mm for SVL. This design allowed us to assess the effects of larval exposure to a contaminant on post-metamorphic development of a native amphibian in a semirealistic field environment. With modifications to decrease flooding or overheating, this enclosure design and species is a good test system for assessing contaminant effects on development of an amphibian from early larval stages through reproductive maturity.
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Affiliation(s)
- Shauni Windle
- Department of Integrative Biology, Oklahoma State University, United States of America.
| | - Scott McMurry
- Department of Integrative Biology, Oklahoma State University, United States of America
| | - Richard Brain
- Syngenta Crop Protection LLC., Greensboro, NC, United States of America
| | - Jonathan Maul
- Syngenta Crop Protection LLC., Greensboro, NC, United States of America
| | - Daniel B Pickford
- Syngenta Crop Protection Ltd., Jealott's Hill International Research Centre, UK
| | - Jeffrey Wolf
- Experimental Pathology Laboratories, Inc., Sterling, VA, United States of America
| | - Jason Belden
- Department of Integrative Biology, Oklahoma State University, United States of America
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3
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Wologo E, Shakil S, Zolkos S, Textor S, Ewing S, Klassen J, Spencer RGM, Podgorski DC, Tank SE, Baker MA, O'Donnell JA, Wickland KP, Foks SSW, Zarnetske JP, Lee‐Cullin J, Liu F, Yang Y, Kortelainen P, Kolehmainen J, Dean JF, Vonk JE, Holmes RM, Pinay G, Powell MM, Howe J, Frei RJ, Bratsman SP, Abbott BW. Stream Dissolved Organic Matter in Permafrost Regions Shows Surprising Compositional Similarities but Negative Priming and Nutrient Effects. GLOBAL BIOGEOCHEMICAL CYCLES 2021; 35:e2020GB006719. [PMID: 33519064 PMCID: PMC7816262 DOI: 10.1029/2020gb006719] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 09/05/2020] [Accepted: 09/22/2020] [Indexed: 05/04/2023]
Abstract
Permafrost degradation is delivering bioavailable dissolved organic matter (DOM) and inorganic nutrients to surface water networks. While these permafrost subsidies represent a small portion of total fluvial DOM and nutrient fluxes, they could influence food webs and net ecosystem carbon balance via priming or nutrient effects that destabilize background DOM. We investigated how addition of biolabile carbon (acetate) and inorganic nutrients (nitrogen and phosphorus) affected DOM decomposition with 28-day incubations. We incubated late-summer stream water from 23 locations nested in seven northern or high-altitude regions in Asia, Europe, and North America. DOM loss ranged from 3% to 52%, showing a variety of longitudinal patterns within stream networks. DOM optical properties varied widely, but DOM showed compositional similarity based on Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis. Addition of acetate and nutrients decreased bulk DOM mineralization (i.e., negative priming), with more negative effects on biodegradable DOM but neutral or positive effects on stable DOM. Unexpectedly, acetate and nutrients triggered breakdown of colored DOM (CDOM), with median decreases of 1.6% in the control and 22% in the amended treatment. Additionally, the uptake of added acetate was strongly limited by nutrient availability across sites. These findings suggest that biolabile DOM and nutrients released from degrading permafrost may decrease background DOM mineralization but alter stoichiometry and light conditions in receiving waterbodies. We conclude that priming and nutrient effects are coupled in northern aquatic ecosystems and that quantifying two-way interactions between DOM properties and environmental conditions could resolve conflicting observations about the drivers of DOM in permafrost zone waterways.
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Affiliation(s)
- Ethan Wologo
- Department of Land Resources and Environmental SciencesMontana State UniversityBozemanMTUSA
| | - Sarah Shakil
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - Scott Zolkos
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
- Woods Hole Research CenterWoods HoleMAUSA
| | - Sadie Textor
- Department of Earth, Ocean and Atmospheric Science and National High Magnetic Field Laboratory Geochemistry GroupFlorida State UniversityTallahasseeFLUSA
| | - Stephanie Ewing
- Department of Land Resources and Environmental SciencesMontana State UniversityBozemanMTUSA
| | - Jane Klassen
- Department of Land Resources and Environmental SciencesMontana State UniversityBozemanMTUSA
| | - Robert G. M. Spencer
- Department of Earth, Ocean and Atmospheric Science and National High Magnetic Field Laboratory Geochemistry GroupFlorida State UniversityTallahasseeFLUSA
| | - David C. Podgorski
- Department of Earth, Ocean and Atmospheric Science and National High Magnetic Field Laboratory Geochemistry GroupFlorida State UniversityTallahasseeFLUSA
| | - Suzanne E. Tank
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - Michelle A. Baker
- Department of Biology and Ecology CenterUtah State UniversityLoganUTUSA
| | | | | | | | - Jay P. Zarnetske
- Department of Earth and Environmental SciencesMichigan State UniversityEast LansingMIUSA
| | - Joseph Lee‐Cullin
- Department of Earth and Environmental SciencesMichigan State UniversityEast LansingMIUSA
| | - Futing Liu
- State Key Laboratory of Vegetation and Environmental Change, Institute of BotanyChinese Academy of SciencesBeijingChina
| | - Yuanhe Yang
- State Key Laboratory of Vegetation and Environmental Change, Institute of BotanyChinese Academy of SciencesBeijingChina
| | | | | | - Joshua F. Dean
- Department of Earth SciencesVrije Universiteit AmsterdamAmsterdamNetherlands
- School of Environmental SciencesUniversity of LiverpoolLiverpoolUK
| | - Jorien E. Vonk
- Department of Earth SciencesVrije Universiteit AmsterdamAmsterdamNetherlands
| | | | - Gilles Pinay
- Environnement‐Ville‐Société (UMR5600) ‐ Centre National de la Recherche Scientifique (CNRS)LyonFrance
| | - Michaela M. Powell
- Department of Land Resources and Environmental SciencesMontana State UniversityBozemanMTUSA
| | - Jansen Howe
- Department of Plant and Wildlife SciencesBrigham Young UniversityProvoUTUSA
| | - Rebecca J. Frei
- Department of Plant and Wildlife SciencesBrigham Young UniversityProvoUTUSA
- Department of Renewable ResourcesUniversity of AlbertaEdmontonAlbertaCanada
| | - Samuel P. Bratsman
- Department of Plant and Wildlife SciencesBrigham Young UniversityProvoUTUSA
| | - Benjamin W. Abbott
- Department of Plant and Wildlife SciencesBrigham Young UniversityProvoUTUSA
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Bardier C, Maneyro R, Toledo LF. The Correlates of in Situ Larval Survivorship of the Threatened South American Toad Melanophryniscus montevidensis (Anura, Bufonidae). SOUTH AMERICAN JOURNAL OF HERPETOLOGY 2020. [DOI: 10.2994/sajh-d-17-00019.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Cecilia Bardier
- Instituto de Investigaciones Biológicas Clemente Estable, Avenida Italia 3318, CP 11600, Montevideo, Uruguay
| | - Raúl Maneyro
- Laboratorio de Sistemática e Historia Natural de Vertebrados, Instituto de Ecología y Ciencias ambientales, Facultad de Ciencias, Universidad de la República, Iguá 4225, CP 11400, Montevideo, Uruguay
| | - Luís Felipe Toledo
- Laboratório de História Natural de Anfíbios Brasileiros, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, CEP 13083‐970, Campinas, São Paulo, Brazil
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5
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Hoskins TD, Dellapina M, Papoulias DM, Boone MD. Effects of larval atrazine exposure in mesocosms on Blanchard's cricket frogs (Acris blanchardi) reared through overwintering and to reproductive age. CHEMOSPHERE 2019; 220:845-857. [PMID: 33395806 DOI: 10.1016/j.chemosphere.2018.12.112] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 12/14/2018] [Accepted: 12/15/2018] [Indexed: 06/12/2023]
Abstract
We exposed Blanchard's cricket frog (Acris blanchardi) tadpoles to atrazine in simulated aquatic communities (outdoor mesocosms) at nominal concentrations of 0, 1, 10, 100, and 200 μg/L and tracked the effects of exposure to spring emergence in the laboratory, as well as to reproductive age in outdoor, terrestrial enclosures. We tested hypotheses that 1) atrazine addition increases the prevalence and intensity of testicular ova (TO) among phenotypic males at metamorphosis and after overwintering, 2) atrazine reduces maturation of ova after overwintering among phenotypic females, and 3) atrazine alters mass, time, and survival to metamorphosis, as well as growth and survival across terrestrial life stages. Atrazine addition increased probability of TO presence at metamorphosis, but only when treatments were pooled and compared to the control, where background atrazine was detected. Atrazine did not influence the intensity of TO among metamorphs. We observed TO among males at spring emergence and at reproductive age regardless of exposure concentration. We found no evidence for effects of exposure on gonadal maturation among females after overwintering. Exposure to 200 μg/L reduced survival to metamorphosis, but atrazine did not affect mass at metamorphosis, time to metamorphosis, or survival or mass after overwintering. We demonstrate that atrazine addition can increase TO prevalence relative to background rates at metamorphosis and that TO are also present among phenotypic males after overwintering. We suggest that this non-model species is sensitive to effects of larval EDC exposures on gonadal development and morphology and that further work with cricket frogs is warranted.
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6
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Hoskins TD, Boone MD. Variation in malathion sensitivity among populations of Blanchard's cricket frogs (Acris blanchardi) and implications for risk assessment. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2017; 36:1917-1923. [PMID: 27982495 DOI: 10.1002/etc.3715] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 06/14/2016] [Accepted: 12/13/2016] [Indexed: 06/06/2023]
Abstract
Intraspecific variability in contaminant sensitivity could undermine risk assessments for nontarget organisms such as amphibians. To test how amphibian populations vary in tolerance to anticipated lethal and sublethal exposures to a pesticide, we exposed Blanchard's cricket frogs (Acris blanchardi) from 3 populations across a broad portion of their range to the insecticide malathion. Exposure in mesocosms to a nominal concentration of 1 mg/L (measured concentrations at 1 h and 24 h postaddition of 0.160 mg/L and 0.062 mg/L, respectively), a realistic direct-overspray scenario, reduced survival to metamorphosis by 43% relative to controls and revealed variation in tolerance among populations. Survival ranged from 74% for the most tolerant population to 18% for the least tolerant population, a 4.1-fold difference. Mass at metamorphosis and time to metamorphosis were unaffected. Although malathion reduced zooplankton abundance, it did not alter food resources (periphyton or phytoplankton relative abundance), or a suite of water-quality variables (pH, temperature, and dissolved oxygen). A 96-h time-to-death assay designed to isolate direct, lethal effects also revealed variation in tolerance among populations. Time to death (mean ± standard error) ranged from 2.4 ± 0.18 h for the least tolerant population to 17.8 ± 4.72 h for the most tolerant population, a 7.4-fold difference. However, relative sensitivities of populations differed in the mesocosm and laboratory studies, which differed in exposure concentrations, suggesting that populations tolerant of high concentrations can be more sensitive to lower concentrations. We suggest that direct overspray could reduce larval survival in the field for this species. Studies assessing the role of contaminants in declines or extrapolating to untested populations, especially across large geographical regions, should quantify the range of intraspecific variation. Risk assessors could address intraspecific variability directly by using an intraspecific uncertainty factor. Environ Toxicol Chem 2017;36:1917-1923. © 2016 SETAC.
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7
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Rumrill CT, Scott DE, Lance SL. Effects of metal and predator stressors in larval southern toads (Anaxyrus terrestris). ECOTOXICOLOGY (LONDON, ENGLAND) 2016; 25:1278-1286. [PMID: 27272662 DOI: 10.1007/s10646-016-1681-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/25/2016] [Indexed: 06/06/2023]
Abstract
Natural and anthropogenic stressors typically do not occur in isolation; therefore, understanding ecological risk of contaminant exposure should account for potential interactions of multiple stressors. Realistically, common contaminants can also occur chronically in the environment. Because parental exposure to stressors may cause transgenerational effects on offspring, affecting their ability to cope with the same or novel environmental stressors, the exposure histories of generations preceding that being tested should be considered. To examine multiple stressor and parental exposure effects we employed a 2 × 2 × 2 factorial design in outdoor 1000-L mesocosms (n = 24). Larval southern toads (Anaxyrus terrestris), bred from parents collected from reference and metal-contaminated sites, were exposed to two levels of both an anthropogenic (copper-0, 30 µg/L Cu) and natural (predator cue - present/absent) stressor and reared to metamorphosis. Toads from the metal-contaminated parental source population were smaller at metamorphosis and had delayed development; i.e., a prolonged larval period. Similarly, larval Cu exposure also reduced size at metamorphosis and prolonged the larval period. We, additionally, observed a significant interaction between larval Cu and predator-cue exposure on larval period, wherein delayed emergence was only present in the 30-µg/L Cu treatments in the absence of predator cues. The presence of parental effects as well as an interaction between aquatic stressors on commonly measured endpoints highlight the importance of conducting multistressor studies across generations to obtain data that are more relevant to field conditions in order to determine population-level effects of contaminant exposure.
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Affiliation(s)
- Caitlin T Rumrill
- Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, 29802, USA
| | - David E Scott
- Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, 29802, USA
| | - Stacey L Lance
- Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, 29802, USA.
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Mikó Z, Ujszegi J, Gál Z, Imrei Z, Hettyey A. Choice of experimental venue matters in ecotoxicology studies: Comparison of a laboratory-based and an outdoor mesocosm experiment. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2015; 167:20-30. [PMID: 26254767 DOI: 10.1016/j.aquatox.2015.07.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 06/16/2015] [Accepted: 07/24/2015] [Indexed: 06/04/2023]
Abstract
The heavy application of pesticides and its potential effects on natural communities has attracted increasing attention to inadvertent impacts of these chemicals. Toxicologists conventionally use laboratory-based tests to assess lethal concentrations of pesticides. However, these tests often do not take into account indirect, interactive and long-term effects, and tend to ignore different rates of disintegration in the laboratory and under natural conditions. Our aim was to investigate the importance of the experimental venue for ecotoxicology tests. We reared tadpoles of the agile frog (Rana dalmatina) in the laboratory and in outdoor mesocosms and exposed them to three initial concentrations of a glyphosate-based herbicide (0, 2 and 6.5 mg a.e./L glyphosate), and to the presence or absence of caged predators (dragonfly larvae). The type of experimental venue had a large effect on the outcome: The herbicide was less lethal to tadpoles reared in outdoor mesocosms than in the laboratory. Further, while the herbicide had a negative effect on development time and on body mass in the laboratory, tadpoles exposed to the herbicide in mesocosms were larger at metamorphosis and developed faster in comparison to those reared in the absence of the herbicide. The effect of the herbicide on morphological traits of tadpoles also differed between the two venues. Finally, in the presence of the herbicide, tadpoles tended to be more active and to stay closer to the bottom of laboratory containers, while tadpole behaviour shifted in the opposite direction in outdoor mesocosms. Our results demonstrate major discrepancies between results of a classic laboratory-based ecotoxicity test and outcomes of an experiment performed in outdoor mesocosms. Consequently, the use of standard laboratory tests may have to be reconsidered and their benefits carefully weighed against the difficulties of performing experiments under more natural conditions. Tests validating experimentally estimated impacts of herbicides under natural conditions and studies identifying key factors determining the applicability of experimental results are urgently needed.
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Affiliation(s)
- Zsanett Mikó
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest 1022, Hungary.
| | - János Ujszegi
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest 1022, Hungary
| | - Zoltán Gál
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest 1022, Hungary
| | - Zoltán Imrei
- Applied Chemical Ecology Department, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest 1022, Hungary
| | - Attila Hettyey
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest 1022, Hungary
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9
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Weir SM, Wooten KJ, Smith PN, Salice CJ. Phthalate ester leachates in aquatic mesocosms: implications for ecotoxicity studies of endocrine disrupting compounds. CHEMOSPHERE 2014; 103:44-50. [PMID: 24309156 DOI: 10.1016/j.chemosphere.2013.10.097] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 10/24/2013] [Accepted: 10/31/2013] [Indexed: 06/02/2023]
Abstract
Aquatic mesocosm experiments have become common throughout the fields of ecology and ecotoxicology. Mesocosm containers are often composed of plastic materials as these are lighter and cheaper than steel cattle tanks. Plastics may contain phthalate esters which may leach from containers, potentially confounding experiments via toxicity or endocrine disruption. The objective of this experiment was to determine the extent to which plastic containers (="tanks") used for mesocosms leach phthalates, and if there are significant differences between tank types and phthalate profiles. We investigated four tank types: fiberglass, polyethylene, poly-vinyl chloride, and polyethylene tanks containing an established aquatic community. We measured six common phthalate esters in water samples collected from each tank every 2 weeks for 8 weeks. There was a significant effect of tank type, time, and time x type interactions on phthalate ester concentrations. Di-(2-ethylhexyl) phthalate was the predominant congener measured in all samples. Fiberglass tanks had greater concentrations of dimethyl phthalate compared to other tank types (more than 600x larger concentration), but no other differences in phthalate profiles among tank types were evident. In addition, tanks with established communities had much higher concentrations of most phthalates at the 6 and 8 week timepoints. Our study confirms that mesocosm tanks of different materials leach phthalates starting immediately after they are filled and continuing for at least 8 weeks, but do so at different rates. Future ecotoxicity experiments should consider the potentially confounding effects of phthalates that may leach from tanks used in experimental mesocosms.
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Affiliation(s)
- Scott M Weir
- The Institute of Environmental and Human Health, Department of Environmental Toxicology, Box 41163, Texas Tech University, Lubbock, TX 79409, United States.
| | - Kimberly J Wooten
- The Institute of Environmental and Human Health, Department of Environmental Toxicology, Box 41163, Texas Tech University, Lubbock, TX 79409, United States
| | - Philip N Smith
- The Institute of Environmental and Human Health, Department of Environmental Toxicology, Box 41163, Texas Tech University, Lubbock, TX 79409, United States
| | - Christopher J Salice
- The Institute of Environmental and Human Health, Department of Environmental Toxicology, Box 41163, Texas Tech University, Lubbock, TX 79409, United States
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10
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Egea-Serrano A, Tejedo M. Contrasting effects of nitrogenous pollution on fitness and swimming performance of Iberian waterfrog, Pelophylax perezi (Seoane, 1885), larvae in mesocosms and field enclosures. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2014; 146:144-153. [PMID: 24296112 DOI: 10.1016/j.aquatox.2013.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 10/27/2013] [Accepted: 11/02/2013] [Indexed: 06/02/2023]
Abstract
Amphibians are declining worldwide and pollutants have been implicated as a major contributor to these declines. To understand these declines, many studies have assessed the impact of pollutants on amphibian behaviour. However, information regarding their effect on locomotor abilities, as well as the intra-specific variation of the tolerance to pollutants, is extremely rare. Further, the majority of studies examining the impact of pollutants on amphibians have been conducted in simplified laboratory settings. Given the complexity of natural systems, determining whether amphibian responses in laboratory studies can be generalized to more realistic natural scenarios is critical. Towards this goal, this study assessed the impact of nitrogenous pollution on survival and fitness-related larval traits (growth, mass and swimming performance) for three populations of the frog Pelophylax perezi, exposed to different degrees of eutrophication in two different and complementary experiments: (1) pond mesocosms, with NH4Cl isolated or combined with NaNO2 and NaNO3, and (2) field enclosures placed in natural streams differing in their degree of pollution. For both mesocosm and field enclosure experiments, larval mortality was unaffected by nitrogenous pollution. However, in the mesocosm experiment, exposure to nitrogenous compounds reduced final larvae mass and growth. In contrast, in the enclosure experiment, polluted locations facilitated final mass and growth of surviving tadpoles. Population-level variation in the effect of pollution was observed for final larval mass in the mesocosm but not in the field enclosure experiment. In addition, although nitrogenous compounds in both mesocosm and natural conditions had no direct effect on absolute larval swimming performance, they may impact the viability of larvae by affecting the relationships between growth and the swimming abilities. The differential pattern found in the impacts of nitrogenous compounds on larvae of P. perezi when raised in different experimental venues (mesocosms and field conditions) points to the convenience of considering more realistic natural scenarios in assessing the impact of pollutants on amphibians.
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Affiliation(s)
- A Egea-Serrano
- Department of Zoology and Physical Anthropology, University of Murcia, 30100 Murcia, Spain.
| | - M Tejedo
- Department of Evolutionary Ecology, Estación Biológica de Doñana, CSIC, Avda, Américo Vespucio s/n., 41092 Sevilla, Spain.
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11
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Biga LM, Blaustein AR. Variations in lethal and sublethal effects of cypermethrin among aquatic stages and species of anuran amphibians. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2013; 32:2855-2860. [PMID: 23999991 DOI: 10.1002/etc.2379] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 08/13/2013] [Accepted: 08/23/2013] [Indexed: 06/02/2023]
Abstract
Despite the use of model species to predict the effects of chemicals in the environment, unpredicted variation in levels of risk to organisms from xenobiotics can be observed. Physiological and morphological differences between species and life stages may lead to differences in sensitivity, while seasonal and spatial variation in pesticide concentrations may affect the level of risk faced by organisms in the environment. Because anurans breed in aquatic habitats subject to contamination by runoff and spraying, they are particularly vulnerable to pesticides. In the present study, embryos, newly hatched larvae, and larvae with limb buds of 3 anuran amphibian species--Pseudacris regilla, Rana cascadae, and Rana aurora--were exposed for 48 h to either 0.5 µg/L or 5.0 µg/L cypermethrin under laboratory conditions. The authors monitored hatching success, larval survival, and measured growth. Additionally, they assayed avoidance behavior 2 wk after exposure or 2 wk after hatching for individuals exposed as embryos. Hatching and survival were not affected in animals of any species exposed as embryos. After exposure as embryos and as newly hatched larvae, however, P. regilla displayed behavioral abnormalities in response to prodding. Cypermethrin increased mortality in P. regilla exposed in both larval stages. Cypermethrin also increased mortality in larval R. cascadae when exposed at the early stage. These results indicate variation in sensitivity to environmentally relevant concentrations of cypermethrin among anuran species and life stages.
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Affiliation(s)
- Lindsay M Biga
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, Oregon, USA
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Egea-Serrano A, Relyea RA, Tejedo M, Torralva M. Understanding of the impact of chemicals on amphibians: a meta-analytic review. Ecol Evol 2012; 2:1382-97. [PMID: 22957147 PMCID: PMC3434931 DOI: 10.1002/ece3.249] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 02/29/2012] [Indexed: 11/29/2022] Open
Abstract
Many studies have assessed the impact of different pollutants on amphibians across a variety of experimental venues (laboratory, mesocosm, and enclosure conditions). Past reviews, using vote-counting methods, have described pollution as one of the major threats faced by amphibians. However, vote-counting methods lack strong statistical power, do not permit one to determine the magnitudes of effects, and do not compare responses among predefined groups. To address these challenges, we conducted a meta-analysis of experimental studies that measured the effects of different chemical pollutants (nitrogenous and phosphorous compounds, pesticides, road deicers, heavy metals, and other wastewater contaminants) at environmentally relevant concentrations on amphibian survival, mass, time to hatching, time to metamorphosis, and frequency of abnormalities. The overall effect size of pollutant exposure was a medium decrease in amphibian survival and mass and a large increase in abnormality frequency. This translates to a 14.3% decrease in survival, a 7.5% decrease in mass, and a 535% increase in abnormality frequency across all studies. In contrast, we found no overall effect of pollutants on time to hatching and time to metamorphosis. We also found that effect sizes differed among experimental venues and among types of pollutants, but we only detected weak differences among amphibian families. These results suggest that variation in sensitivity to contaminants is generally independent of phylogeny. Some publication bias (i.e., selective reporting) was detected, but only for mass and the interaction effect size among stressors. We conclude that the overall impact of pollution on amphibians is moderately to largely negative. This implies that pollutants at environmentally relevant concentrations pose an important threat to amphibians and may play a role in their present global decline.
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Affiliation(s)
- Andrés Egea-Serrano
- Facultad de Biología, Departamento de Zoología y Antropología Física, Universidad de Murcia30100 Murcia, Spain
| | - Rick A Relyea
- Department of Biological Sciences, University of Pittsburgh101 Clapp Hall, Pittsburgh, Pennsylvania 15260
| | - Miguel Tejedo
- Department of Evolutionary Ecology, Estación Biológica de DoñanaCSIC, Avda. Américo Vespucio s/n, 41092 Sevilla, Spain
| | - Mar Torralva
- Facultad de Biología, Departamento de Zoología y Antropología Física, Universidad de Murcia30100 Murcia, Spain
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Winkler JD, Van Buskirk J. Influence of experimental venue on phenotype: multiple traits reveal multiple answers. Funct Ecol 2012. [DOI: 10.1111/j.1365-2435.2012.01965.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Todd BD, Willson JD, Bergeron CM, Hopkins WA. Do effects of mercury in larval amphibians persist after metamorphosis? ECOTOXICOLOGY (LONDON, ENGLAND) 2012; 21:87-95. [PMID: 21850489 DOI: 10.1007/s10646-011-0768-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/10/2011] [Indexed: 05/31/2023]
Abstract
Despite widespread concern about the role of environmental contaminants in global amphibian declines, and evidence that post-metamorphic life stages contribute disproportionately to amphibian population dynamics, most studies in amphibian ecotoxicology focus on larval life stages. Studies that focus solely on early life stages may miss important effects of contaminant exposure, such as latent effects that manifest some time after previous exposure. Moreover, it is often assumed that effects observed in amphibian larvae will persist to affect survival or reproduction later in life. We used terrestrial enclosures to determine whether exposure to mercury (Hg) through maternal transfer and/or larval diet had any adverse effects in post-metamorphic American toads (Bufo americanus). We found a 5% difference in size at metamorphosis that was attributed to maternal Hg exposure persisted for 1 year in the terrestrial environment, resulting in a 7% difference at the conclusion of the study. Although patterns of survival differed among treatments through time, we found no overall difference in survival after 1 year. We also found no evidence of emergent latent effects in the terrestrial toads that could be attributed to earlier exposure. Our results indicate that adverse effects of maternal Hg exposure that were observed in larval amphibians may persist to affect later terrestrial life stages but that no novel adverse effects developed when animals were raised in a semi-natural environment. Moreover, we found no evidence of persistent effects of dietary Hg exposure in larvae, highlighting a need for greater focus on maternal effects in amphibian ecotoxicology. Finally, we suggest an increase in the use of longitudinal studies to better understand contaminant impacts to amphibian populations via effects in both aquatic and terrestrial life stages.
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Affiliation(s)
- Brian D Todd
- Department of Fish and Wildlife Conservation, Virginia Tech, 100 Cheatham Hall, Blacksburg, VA 24061, USA.
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Bergeron CM, Hopkins WA, Bodinof CM, Budischak SA, Wada H, Unrine JM. Counterbalancing effects of maternal mercury exposure during different stages of early ontogeny in American toads. THE SCIENCE OF THE TOTAL ENVIRONMENT 2011; 409:4746-52. [PMID: 21903241 DOI: 10.1016/j.scitotenv.2011.07.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 06/30/2011] [Accepted: 07/11/2011] [Indexed: 05/13/2023]
Abstract
Maternal transfer of environmental contaminants is a disadvantageous parental effect which can have long-lasting implications for offspring fitness. We investigated the effects of mercury (Hg) on the reproductive success of female amphibians and the subsequent effects of maternal transfer on the development of their offspring. American toads (Bufo americanus) maternally transferred Hg to their eggs, and there was a negative relationship between Hg concentrations and the percentage of viable hatchlings produced in clutches. However, when we continued to monitor larvae that successfully hatched, we found 21% greater metamorphic success in larvae from Hg-exposed mothers compared to reference larvae. The negative effect in the embryonic stage and positive effect in the larval stage counterbalanced one another, ultimately resulting in no difference in predicted terrestrial recruitment, regardless of maternal Hg exposure. Our findings demonstrate that maternal effects on survival manifesting at different stages in ontogeny have the potential to produce complicated outcomes.
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Affiliation(s)
- Christine M Bergeron
- Wildlife Ecotoxicology and Physiological Ecology Program, Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA 24061, USA
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Todd BD, Bergeron CM, Hepner MJ, Burke JN, Hopkins WA. Does maternal exposure to an environmental stressor affect offspring response to predators? Oecologia 2011; 166:283-90. [PMID: 21416404 PMCID: PMC3074075 DOI: 10.1007/s00442-011-1961-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Accepted: 03/02/2011] [Indexed: 11/25/2022]
Abstract
There is growing recognition of the ways in which maternal effects can influence offspring size, physiological performance, and survival. Additionally, environmental contaminants increasingly act as stressors in maternal environments, possibly leading to maternal effects on subsequent offspring. Thus, it is important to determine whether contaminants and other stressors can contribute to maternal effects, particularly under varied ecological conditions that encompass the range under which offspring develop. We used aquatic mesocosms to determine whether maternal effects of mercury (Hg) exposure shape offspring phenotype in the American toad (Bufo americanus) in the presence or absence of larval predators (dragonfly naiads). We found significant maternal effects of Hg exposure and significant effects of predators on several offspring traits, but there was little evidence that maternal effects altered offspring interactions with predators. Offspring from Hg-exposed mothers were 18% smaller than those of reference mothers. Offspring reared with predators were 23% smaller at metamorphosis than those reared without predators. There was also evidence of reduced larval survival when larvae were reared with predators, but this was independent of maternal effects. Additionally, 5 times more larvae had spinal malformations when reared without predators, suggesting selective predation of malformed larvae by predators. Lastly, we found a significant negative correlation between offspring survival and algal density in mesocosms, indicating a role for top-down effects of predators on periphyton communities. Our results demonstrate that maternal exposure to an environmental stressor can induce phenotypic responses in offspring in a direction similar to that produced by direct exposure of offspring to predators.
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Affiliation(s)
- Brian D Todd
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA 24061, USA.
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Bulen BJ, Distel CA. Carbaryl concentration gradients in realistic environments and their influence on our understanding of the tadpole food web. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2011; 60:343-350. [PMID: 21221965 DOI: 10.1007/s00244-010-9630-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 12/09/2010] [Indexed: 05/30/2023]
Abstract
Although exposure to pesticides has been correlated with amphibian declines, the mechanism of their role remains enigmatic. Declines have been associated with sublethal exposure, but few outdoor studies have evaluated impacts of low pesticide concentrations. Understanding the effects of a range of pesticide concentrations on amphibians in outdoor mesocosms provides a framework for both direct and indirect effects of exposure. Indirect effects are challenging to glean from lab studies, which typically lack a food web. Our design tested direct and indirect effects of exposure to the insecticide carbaryl on the American toad (Bufo americanus) and the northern leopard frog (Rana pipiens) tadpole survival and growth. We evaluated the effects of five concentrations (2.0, 0.2, 0.02, 0.002, and 0 mg carbaryl/l). Specifically, we predicted a threshold effect in which carbaryl concentrations great enough to reduce zooplankton abundance would have negative indirect effects on tadpoles, but the degree of these effects would not be concentration-specific. Similarly, we predicted that lower carbaryl concentrations (where zooplankton abundance was not reduced) would not differ in effect from controls. We did not observe a threshold effect or any negative effect on tadpoles. The highest carbaryl concentration expedited the time to metamorphosis in the northern leopard frogs by ~4 days. The toads were unaffected by any concentration of carbaryl. Despite significant reductions in zooplankton abundance and increases in phytoplankton abundance, periphyton abundance was unaffected by carbaryl. Taken together, these results suggest that despite evidence from studies using single concentrations of pesticides, trophic cascade models do not sufficiently explain sublethal effects on larval amphibians.
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Williams BK, Semlitsch RD. Larval responses of three midwestern anurans to chronic, low-dose exposures of four herbicides. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2010; 58:819-27. [PMID: 19768486 DOI: 10.1007/s00244-009-9390-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Accepted: 08/31/2009] [Indexed: 05/28/2023]
Abstract
Low levels of agricultural herbicides often contaminate surface water and might persist throughout the growing season, potentially acting as stressors on aquatic organisms. Although low-dose, chronic exposures to agrochemicals are likely common for many nontarget organisms, studies addressing these effects using end-use herbicide formulations are rare. We exposed three common species of tadpoles to conservative levels of atrazine, S-metolachlor, and glyphosate end-use herbicide formulations throughout the larval period to test for survival differences or life-history trait alterations. Exposure to the glyphosate product Roundup WeatherMax at 572 ppb glyphosate acid equivalents (a.e.) resulted in 80% mortality of western chorus frog tadpoles, likely as a result of a unique surfactant formulation. Exposure to WeatherMax or Roundup Original Max at 572 ppb a.e. also lengthened the larval period for American toads. Chronic atrazine and S-metolachlor exposures induced no significant negative effects on survival, mass at metamorphosis, or larval period length at the levels tested. These results highlight the importance of explicitly tying chronic tests to the natural environment and considering contributions of surfactant/adjuvant components to end-use formulation toxicities, even between very similar products.
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Affiliation(s)
- Bethany K Williams
- Division of Biological Sciences, University of Missouri, 212 Tucker Hall, Columbia, MO 65211, USA.
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Williams BK, Rittenhouse TAG, Semlitsch RD. Leaf litter input mediates tadpole performance across forest canopy treatments. Oecologia 2007; 155:377-84. [PMID: 18049825 DOI: 10.1007/s00442-007-0920-y] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2006] [Accepted: 11/07/2007] [Indexed: 11/24/2022]
Abstract
Understanding the mechanisms limiting the distributions of organisms is necessary for predicting changes in community composition along habitat gradients. In many areas of the USA, land originally cleared for agriculture has been undergoing a process of reforestation, creating a gradient of canopy cover. For small temporary wetlands, this gradient can alter abiotic conditions and influence the resource base of wetland food webs by affecting litter inputs. As distributions of amphibians and many other temporary wetland taxa correlate with canopy cover, we experimentally manipulated shade levels and litter types in pond mesocosms to explore mechanisms limiting species performance in wetlands with canopy cover. Most differences between ponds were mediated by litter type rather than direct effects of shading. Although all three amphibian species tested are open-canopy specialists, spring peepers were the only species to show decreased survival in shaded ponds. Pond litter type generally had strong effects on growth and development rates, with tadpoles of two species in grass litter ponds growing to twice the size of, and metamorphosing 7 days earlier than, those in leaf litter ponds. Contrary to our initial hypothesis, shade level and litter type showed very few significant interactions. Our results indicate that the effects of shading cannot be considered in isolation of vegetation changes in pond basins when evaluating the effects of forest succession on temporary pond communities.
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Affiliation(s)
- Bethany K Williams
- Division of Biological Sciences, University of Missouri, Columbia, MO 65211, USA.
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Abstract
The use of amphibians as models in ecological research has a rich history. From an early foundation in studies of amphibian natural history sprang generations of scientists who used amphibians as models to address fundamental questions in population and community ecology. More recently, in the wake of an environment that human disturbances rapidly altered, ecologists have adopted amphibians as models for studying applied ecological issues such as habitat loss, pollution, disease, and global climate change. Some of the characteristics of amphibians that make them useful models for studying these environmental problems are highlighted, including their trophic importance, environmental sensitivity, research tractability, and impending extinction. The article provides specific examples from the recent literature to illustrate how studies on amphibians have been instrumental in guiding scientific thought on a broad scale. Included are examples of how amphibian research has transformed scientific disciplines, generated new theories about global health, called into question widely accepted scientific paradigms, and raised awareness in the general public that our daily actions may have widespread repercussions. In addition, studies on amphibian declines have provided insight into the complexity in which multiple independent factors may interact with one another to produce catastrophic and sometimes unpredictable effects. Because of the complexity of these problems, amphibian ecologists have been among the strongest advocates for interdisciplinary research. Future studies of amphibians will be important not only for their conservation but also for the conservation of other species, critical habitats, and entire ecosystems.
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Affiliation(s)
- William A Hopkins
- Wildlife and Ecotoxicology and Physiological Ecology Program, Department of Fisheries and Wildlife Services, Virginia Polytchnic Institute and State University, 100 Cheatham Hall, Blacksburg, Virginia 24061, USA.
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Boone MD, Semlitsch RD, Little EE, Doyle MC. Multiple stressors in amphibian communities: effects of chemical contamination, bullfrogs, and fish. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2007; 17:291-301. [PMID: 17479852 DOI: 10.1890/1051-0761(2007)017[0291:msiace]2.0.co;2] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
A leading hypothesis of amphibian population declines is that combinations of multiple stressors contribute to declines. We examined the role that chemical contamination, competition, and predation play singly and in combination in aquatic amphibian communities. We exposed larvae of American toads (Bufo americanus), southern leopard frogs (Rana sphenocephala), and spotted salamanders (Ambystoma maculatum) to overwintered bullfrog tadpoles (R. catesbeiana), bluegill sunfish (Lepomis macrochirus), the insecticide carbaryl, and ammonium nitrate fertilizer in 1000-L mesocosms. Most significantly, our study demonstrated that the presence of multiple factors reduced survival of B. americanus and A. maculatum and lengthened larval periods of R. sphenocephala. The presence of bluegill had the largest impact on the community; it eliminated B. americanus and A. maculatum and reduced the abundance of R. sphenocephala. Chemical contaminants had the second strongest effect on the community with the insecticide, reducing A. maculatum abundance by 50% and increasing the mass of anurans (frogs and toads) at metamorphosis; the fertilizer positively influenced time and mass at metamorphosis for both anurans and A. maculatum. Presence of overwintered bullfrogs reduced mass and increased time to metamorphosis of anurans. While both bluegill and overwintered bullfrog tadpoles had negative effects on the amphibian community, they performed better in the presence of one another and in contaminated habitats. Our results indicate that predicting deleterious combinations from single-factor effects may not be straightforward. Our research supports the hypothesis that combinations of factors can negatively impact some amphibian species and could contribute to population declines.
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Affiliation(s)
- Michelle D Boone
- Division of Biological Sciences, 105 Tucker Hall, University of Missouri, Columbia, Missouri 65211, USA.
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