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Kloskowski J. Total Non-Consumptive Effects of Fish on Pelobates fuscus and Hyla orientalis Tadpoles in Pond Enclosure Experiments. Zoolog Sci 2018; 35:528-534. [PMID: 30520359 DOI: 10.2108/zs180036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Most research on non-consumptive predator effects on amphibian larvae has been conducted in laboratory or mesocosm designs. Here, Pelobates fuscus and Hyla orientalis tadpoles were separately exposed to non-lethal (free-moving, but with tied mouthparts) common carp Cyprinus carpio for one week in enclosures placed in a pond densely stocked with fish. Tadpoles exposed to nonlethal fish did not differ in mortality, body mass, or, except for deeper tail fin depth in P. fuscus, morphological plasticity from controls kept in a fishless pond. Hyla orientalis tadpoles recovered from the fish treatment were subsequently enclosed until metamorphosis in either the pond with fish or the fishless pond. Metamorphs from the pond containing fish were heavier, and did not differ in survivorship or development time from their counterparts initially kept in the fish treatment and then transferred to the fishless pond or from controls kept the entire time under fish-free conditions. The lack of apparent metamorphic costs is consistent with previous experiments on anuran larvae, but the morphological defenses induced (or their absence) are not. In the fish-dominated pond, carp indirectly affected tadpole developmental responses by generating turbidity, through adverse impacts on submerged vegetation and predatory insects, and by increasing food resource (unicellular algae) levels. While the present study does not question the validity of laboratory and mesocosm experiments on the costs of non-consumptive predator effects on amphibian larvae, their outcomes cannot easily be extrapolated to ecologically complex natural habitats.
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Affiliation(s)
- Janusz Kloskowski
- Institute of Zoology, Poznań University of Life Sciences, Wojska Polskiego 71C, 60-625 Poznań, Poland
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2
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Ruehl CB, Vance‐Chalcraft H, Chalcraft DR. Cooccurrence of prey species alters the impact of predators on prey performance through multiple mechanisms. Ecol Evol 2018; 8:8894-8907. [PMID: 30271553 PMCID: PMC6157665 DOI: 10.1002/ece3.4413] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 05/29/2018] [Accepted: 06/27/2018] [Indexed: 11/08/2022] Open
Abstract
When prey are differentially affected by intra and interspecific competition, the cooccurrence of multiple prey species alters the per capita availability of food for a particular prey species which could alter how prey respond to the threat of predation, and hence the overall-effect of predators. We conducted an experiment to examine the extent to which the nonconsumptive and overall effect of predatory water bugs on snail and tadpole traits (performance and morphology) depended on whether tadpoles and snails cooccurred. Tadpoles and snails differed in their relative susceptibility to intraspecific and interspecific competition, and predators affected both prey species via consumptive and nonconsumptive mechanisms. Furthermore, the overall effect of predators often depended on whether another prey species was present. The reasoning for why the overall effect of predators depended on whether prey species cooccurred, however, differed for each of the response variables. Predators affected snail body growth via nonconsumptive mechanisms, but the change in the overall effect of predators on snail body growth was attributable to how snails responded to competition in the absence of predators, rather than a change in how snails responded to the threat of predation. Predators did not affect tadpole body growth via nonconsumptive mechanisms, but the greater vulnerability of competitively superior prey (snails) to predators increased the strength of consumptive mechanisms (and hence the overall effect) through which predators affected tadpole growth. Predators affected tadpole morphology via nonconsumptive mechanisms, but the greater propensity for predators to kill competitively superior prey (snails) enhanced the ability of tadpoles to alter their morphology in response to the threat of predation by creating an environment where tadpoles had a higher per capita supply of food available to invest in the development of morphological defenses. Our work indicates that the mechanisms through which predators affect prey depends on the other members of the community.
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Affiliation(s)
- Clifton B. Ruehl
- Department of BiologyEast Carolina UniversityGreenvilleNorth Carolina
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Álvarez-Manzaneda I, de Vicente I. Assessment of toxic effects of magnetic particles used for lake restoration on Chlorella sp. and on Brachionus calyciflorus. CHEMOSPHERE 2017; 187:347-356. [PMID: 28858716 DOI: 10.1016/j.chemosphere.2017.08.129] [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: 06/06/2017] [Revised: 07/31/2017] [Accepted: 08/24/2017] [Indexed: 06/07/2023]
Abstract
Laboratory tests, by following standardized Organization for Economic Co-operation and Development (OECD) protocols, were run for evaluating the acute effects of iron magnetic microparticles (MPs), recently proposed for lake restoration, on Chlorella sp. (algal growth) and on the rotifer B. calyciflorus (mortality). In addition, the MPs potential indirect effects on rotifer egg bank were assessed by performing hatching rate test with B. calyciflorus cysts in contact with dissolved iron (Tot-Fedis). In the algal growth test, no inhibition occurred at the two lowest MPs concentrations (0.01 and 0.05 g l-1) which would correspond, considering the adsorption efficiency ratio (Phosphorus: MPs), to P concentrations lower than 0.94 mg P l-1, much higher than typical concentrations found in natural waters. For higher MPs dose (EC50 for Chlorella sp. was 0.15 g l-1), no nutrient limitations but high turbidity and Tot-Fedis values cause negative effects on algal growth. For the case of B. calyciflorus, LC50 was 1.63 g MPs l-1 (corresponding to 30.7 mg P l-1). When analyzing Tot-Fedis effect, the hatching rate of B. calyciflorus cysts was 100% for all treatments. To sum up our results for B. calyciflorus acute and chronic toxicity tests, it is extremely unlikely the mortality of adult organisms in contact with MPs as well as an affectation of the rotifer egg bank. In conclusion, it is expected that MPs addition in a real whole-lake application cause minor lethal and sublethal effects on both Chlorella sp. and B. calyciflorus.
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Affiliation(s)
- I Álvarez-Manzaneda
- Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, 18071, Spain; Instituto del Agua, Universidad de Granada, 18071, Spain
| | - I de Vicente
- Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, 18071, Spain; Instituto del Agua, Universidad de Granada, 18071, Spain.
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Mikó Z, Ujszegi J, Gál Z, Hettyey A. Standardize or Diversify Experimental Conditions in Ecotoxicology? A Case Study on Herbicide Toxicity to Larvae of Two Anuran Amphibians. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2017; 73:562-569. [PMID: 28660298 DOI: 10.1007/s00244-017-0427-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 06/19/2017] [Indexed: 06/07/2023]
Abstract
Despite a steeply increasing number of ecotoxicological studies on the effects of pesticides on nontarget organisms, studies assessing the adequacy and reliability of different experimental approaches have remained scarce. We scrutinized effects of a glyphosate-based herbicide on larvae of two European anuran amphibians by estimating species-specific LC50 values, assessing how an additional stress factor may influence outcomes, and investigating whether replicate experiments yielded qualitatively the same results. We exposed Rana dalmatina and Bufo bufo tadpoles to two predator treatments (no predator vs. predator chemical cues) combined with varying herbicide concentrations, repeated the experiment with a subset of the experimental treatments and partly with slight modifications 1 week later and assessed survival. Our results indicated that the herbicide was moderately toxic to tadpoles. The presence of predator chemical cues did not affect the lethality of the herbicide in either species. The estimated sensitivity of R. dalmatina tadpoles varied considerably across experiments, whereas in case of B. bufo LC50 values remained very similar. Our results suggest that differences in the experimental setup may often have no influence on the measured effects of pesticides, whereas replicated experiments can deliver widely differing results in other cases, perhaps depending on the studied species, the population origin of the tested individuals, or the test conditions. This draws attention to the suggestion that strict standardization may not deliver widely applicable insights into the toxicity of contaminants and, instead, intentionally introducing variation into the design of ecotoxicological experiments and replicating entire experiments may prove highly beneficial.
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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
- Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest, 1117, 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
- Agricultural Biotechnology Institute, NARIC, Szent-Györgyi Albert utca 4, Gödöllő, 2100, 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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Deans RA, Chalcraft DR. Matrix context and patch quality jointly determine diversity in a landscape‐scale experiment. OIKOS 2016. [DOI: 10.1111/oik.03809] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Robert A. Deans
- Dept of Biology and East Carolina Biodiversity Initiative East Carolina Univ. Greenville NC 27858 USA
- Dept of Integrative Biology, College of Natural Sciences Univ. of Texas Austin TX 78712 USA
| | - David R. Chalcraft
- Dept of Biology and East Carolina Biodiversity Initiative East Carolina Univ. Greenville NC 27858 USA
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Albecker M, Vance-Chalcraft HD. Mismatched anti-predator behavioral responses in predator-naïve larval anurans. PeerJ 2015; 3:e1472. [PMID: 26664805 PMCID: PMC4675102 DOI: 10.7717/peerj.1472] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 11/12/2015] [Indexed: 11/20/2022] Open
Abstract
Organisms are adept at altering behaviors to balance the tradeoff between foraging and predation risk in spatially and temporally shifting predator environments. In order to optimize this tradeoff, prey need to be able to display an appropriate response based on degree of predation risk. To be most beneficial in the earliest life stages in which many prey are vulnerable to predation, innate anti-predator responses should scale to match the risk imposed by predators until learned anti-predator responses can occur. We conducted an experiment that examined whether tadpoles with no previous exposure to predators (i.e., predator-naive) exhibit innate antipredator behavioral responses (e.g., via refuge use and spatial avoidance) that match the actual risk posed by each predator. Using 7 treatments (6 free-roaming, lethal predators plus no-predator control), we determined the predation rates of each predator on Lithobates sphenocephalus tadpoles. We recorded behavioral observations on an additional 7 nonlethal treatments (6 caged predators plus no-predator control). Tadpoles exhibited innate responses to fish predators, but not non-fish predators, even though two non-fish predators (newt and crayfish) consumed the most tadpoles. Due to a mismatch between innate response and predator consumption, tadpoles may be vulnerable to greater rates of predation at the earliest life stages before learning can occur. Thus, naïve tadpoles in nature may be at a high risk to predation in the presence of a novel predator until learned anti-predator responses provide additional defenses to the surviving tadpoles.
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Affiliation(s)
- Molly Albecker
- Department of Biology and East Carolina Biodiversity Initiative, East Carolina University , Greenville, NC , United States
| | - Heather D Vance-Chalcraft
- Department of Biology and East Carolina Biodiversity Initiative, East Carolina University , Greenville, NC , United States
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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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8
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Hoskins TD, Boone MD. Evaluating the Need for Supplemental Shallow Water Access for Amphibians Reared in Mesocosms. COPEIA 2015. [DOI: 10.1643/ch-14-120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Benard MF. Warmer winters reduce frog fecundity and shift breeding phenology, which consequently alters larval development and metamorphic timing. GLOBAL CHANGE BIOLOGY 2015; 21:1058-1065. [PMID: 25263760 DOI: 10.1111/gcb.12720] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 07/24/2014] [Indexed: 06/03/2023]
Abstract
One widely documented phenological response to climate change is the earlier occurrence of spring-breeding events. While such climate change-driven shifts in phenology are common, their consequences for individuals and populations have rarely been investigated. I addressed this gap in our knowledge by using a multi-year observational study of six wood frog (Rana sylvatica) populations near the southern edge of their range. I tested first if winter temperature or precipitation affected the date of breeding and female fecundity, and second if timing of breeding affected subsequent larval development rate, mass at metamorphosis, date of metamorphosis, and survival. Warmer winters were associated with earlier breeding but reduced female fecundity. Winter precipitation did not affect breeding date, but was positively associated with female fecundity. There was no association between earlier breeding and larval survival or mass at metamorphosis, but earlier breeding was associated with delayed larval development. The delay in larval development was explained through a counterintuitive correlation between breeding date and temperature during larval development. Warmer winters led to earlier breeding, which in turn was associated with cooler post-breeding temperatures that slowed larval development. The delay in larval development did not fully compensate for the earlier breeding, such that for every 2 days earlier that breeding took place, the average date of metamorphosis was 1 day earlier. Other studies have found that earlier metamorphosis is associated with increased postmetamorphic growth and survival, suggesting that earlier breeding has beneficial effects on wood frog populations.
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Affiliation(s)
- Michael F Benard
- Department of Biology, Case Western Reserve University, Cleveland, OH, 44106-7080, USA
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10
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Searcy CA, Snaas H, Shaffer HB. Determinants of size at metamorphosis in an endangered amphibian and their projected effects on population stability. OIKOS 2014. [DOI: 10.1111/oik.01775] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christopher A. Searcy
- Dept of Evolution and Ecology and Center for Population Biology; Univ. of California; One Shields Avenue Davis CA 95616 USA
| | - Helen Snaas
- HAS Univ. of Applied Sciences; Onderwijsboulevard 221 NL-5223 DE ‘s-Hertogenbosch the Netherlands
| | - H. Bradley Shaffer
- Dept of Ecology and Evolutionary Biology; 621 Charles E. Young Drive South and La Kretz Center for California Conservation Science, 619 Charles E. Young Drive South, Univ. of California; Los Angeles CA 90095 USA
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11
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Simulating Selective Mortality on Tadpole Populations in the Lab Yields Improved Estimates of Effect Size in Nature. J HERPETOL 2014. [DOI: 10.1670/12-206] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
Ecosystems provide a vast array of services for human societies, but understanding how various organisms contribute to the functions that maintain these services remains an important ecological challenge. Predators can affect ecosystem functions through a combination of top-down trophic cascades and bottom-up effects on nutrient dynamics. As the most abundant vertebrate predator in many eastern US forests, woodland salamanders (Plethodon spp.) likely affect ecosystems functions. We examined the effects of red-backed salamanders (Plethodon cinereus) on a variety of forest ecosystem functions using a combined approach of large-scale salamander removals (314-m2 plots) and small-scale enclosures (2 m2) where we explicitly manipulated salamander density (0, 0.5, 1, 2, 4 m−2). In these experiments, we measured the rates of litter and wood decomposition, potential nitrogen mineralization and nitrification rates, acorn germination, and foliar insect damage on red oak seedlings. Across both experimental venues, we found no significant effect of red-backed salamanders on any of the ecosystem functions. We also found no effect of salamanders on intraguild predator abundance (carabid beetles, centipedes, spiders). Our study adds to the already conflicting evidence on effects of red-backed salamander and other amphibians on terrestrial ecosystem functions. It appears likely that the impact of terrestrial amphibians on ecosystem functions is context dependent. Future research would benefit from explicitly examining terrestrial amphibian effects on ecosystem functions under a variety of environmental conditions and in different forest types.
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Martin LJ, Blossey B. Intraspecific variation overrides origin effects in impacts of litter-derived secondary compounds on larval amphibians. Oecologia 2013; 173:449-59. [DOI: 10.1007/s00442-013-2624-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 02/08/2013] [Indexed: 10/27/2022]
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Costa ZJ, Vonesh JR. Interspecific Differences in the Direct and Indirect Effects of Two Neotropical Hylid Tadpoles on Primary Producers and Zooplankton. Biotropica 2013. [DOI: 10.1111/btp.12032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zacharia J. Costa
- Department of Biology; Virginia Commonwealth University; 1000 W. Cary St; Richmond; VA; 23284-2012; U.S.A
| | - James R. Vonesh
- Department of Biology; Virginia Commonwealth University; 1000 W. Cary St; Richmond; VA; 23284-2012; U.S.A
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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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17
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Tadpole mortality varies across experimental venues: do laboratory populations predict responses in nature? Oecologia 2012; 169:861-8. [PMID: 22298111 DOI: 10.1007/s00442-012-2260-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 01/13/2012] [Indexed: 10/14/2022]
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Novak M, Wootton JT. Estimating nonlinear interaction strengths: an observation-based method for species-rich food webs. Ecology 2008; 89:2083-9. [PMID: 18724718 DOI: 10.1890/08-0033.1] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Efforts to estimate the strength of species interactions in species-rich, reticulate food webs have been hampered by the multitude of direct and indirect interactions such systems exhibit and have been limited by an assumption that pairwise interactions display linear functional forms. Here we present a new method for directly measuring, on a per capita basis, the nonlinear strength of trophic species interactions within such food webs. This is an observation-based method, requiring three pieces of information: (1) species abundances, (2) predator and prey-specific handling times, and (3) data from predator-specific feeding surveys in which the number of individuals observed feeding on each of the predator's prey species has been tallied. The method offers a straightforward way to assess the completeness of one's sampling effort in accurately estimating interaction strengths through the construction of predator-specific prey accumulation curves. The method should be applicable to a variety of systems in which empirical estimates of direct interaction strengths have thus far remained elusive.
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Affiliation(s)
- Mark Novak
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637, 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
1. Pairs of European Triturus newt species of similar size tend not to co-occur syntopically, suggesting that similarity in body size is associated with competitive interactions that prevent coexistence. I tested this hypothesis with an experiment involving larvae of four species in 675-L artificial ponds. 2. There were strong interactions between most species pairs. Even the small T. helveticus had a clear impact on the larger T. alpestris. Pairs of species with different body sizes did not interact less strongly. 3. A standard increase in competitor biomass (c. 2 g mass at metamorphosis) caused 42% lower expected survival from hatching to 1 year of age, regardless of whether the species were of similar or different size. In most cases this resulted from delayed metamorphosis, reduced size at emergence, and slightly lower larval survival. 4. A standard increase in competitor density (0.74 individuals m(-2)) caused a greater reduction in expected 1-year survival when the competitor was larger (18% decline) than when both species were of similar size (6% decline), primarily because the very large T. cristatus consumed the smallest species. 5. These findings suggest that species interactions during the larval stage cannot explain distribution patterns of same- and different-sized Triturus.
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Affiliation(s)
- Josh VAN Buskirk
- Institute of Zoology, University of Zürich, Zürich, Switzerland.
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Richter-Boix A, Llorente GA, Montori A. Structure and dynamics of an amphibian metacommunity in two regions. J Anim Ecol 2007; 76:607-18. [PMID: 17439477 DOI: 10.1111/j.1365-2656.2007.01232.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. The concept of metacommunity is based on the hypothesis that species occurrence depends on species dynamics and interactions on local and regional scales via the movements of individuals between localities. Metacommunity approaches are currently being applied to pond breeding taxa such as amphibians. 2. Given that animal movement is also influenced by the physical quality of the matrix to be crossed to reach a breeding habitat and by the affinity of the species for specific terrestrial habitats, matrix characteristics may enhance or hinder dispersal success. These characteristics would, in turn, affect the composition of larval assemblages at local level and, consequently, determine metacommunity structure and dynamics. 3. Here we compared the structures and dynamics of two metacommunities with the same pool of anurans along similar freshwater gradients in two regions that are well differentiated in terms of their respective terrestrial matrix. 4. Abundance of tadpole species and species assemblage in the two regions were determined principally by local processes (at pond level); however, the structure and dynamics of the communities differed. In one region species abundance was explained in part by landscape factors and consequently showed lower co-occurrence and lower colonization rates (species sorting models) indicating that terrestrial habitat could restrict animal movements, whereas in the other region higher co-occurrence and higher colonization rates (mass effect models) indicated low dispersal limitations.
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Affiliation(s)
- Alex Richter-Boix
- Department Biologia Animal, Facultat de Biología, Universitat de Barcelona, Avenue Diagonal 645, Barcelona, Spain.
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23
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