Understanding of the impact of chemicals on amphibians: a meta‐analytic review

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.

Toxicidad del herbicida Propanil (Propanil Trust® 500EC) en embriones y renacuajos de tres especies de anuros

“…No obstante, numerosas investigaciones indican que estos agroquímicos pueden provocar consecuencias directas e indirectas en la supervivencia de organismos no blanco asociados a la agricultura, como los anfibios (Bridges, 2000;Greulich y Pflugmacher, 2003;Lajmanovich et al, 2003;Bernal et al, 2009a, b;Jayawardena et al, 2010;Egea et al, 2012;Reylea, 2012;Henao et al, 2015a;Henao et al, 2015b). De acuerdo con nuestros resultados, la exposición al herbicida Propanil en embriones y renacuajos de anuros resultó letal en las pruebas de laboratorio, ya que para todos los casos los valores CL 50 fueron inferiores a la concentración usada en campo (8400 mg/L), lo que concuerda con Moore et al, (1998), Jayawardena et al, (2010), y Jayawardena et al, (2011, quienes reportaron que el herbicida Propanil fue tóxico bajo condiciones de laboratorio en renacuajos de X. laevis, P. cruciger y B. melanostictus.…”

“…Este resultado coincide con Henao et al, (2015a), quienes hallaron una mayor tolerancia en los embriones en comparación con los renacuajos de H. crepitans, R. humboldti y E. pustulosus a la mezcla del herbicida glifosato (Roundup ® Activo) con el Cosmo-Flux ® 411F en condiciones de laboratorio. Una mayor resistencia en estadíos embrionarios ha sido reportada por varios autores en diferentes pesticidas (Bridges, 2000;Bridges y Semlitsch, 2000;Greulich y Pflugmacher, 2003;Edginton et al, 2004;Ortiz-Santaliestra et al, 2006;Egea et al, 2012), los cuales atribuyen la menor toxicidad a la matriz gelatinosa de los embriones que los protege durante las primeras horas de experimentación. Caso contrario sucede con los renacuajos, quienes presentan estructuras sensibles a los contaminantes, como las branquias o el sistema nervioso (Ortiz-Santaliestra et al, 2006).…”

Breeding populations of Bombina orientalis Boulenger, 1890 (Amphibia Anura Bombinatoridae) in degraded urban habitat in Vladivostok, Russia

“…One of the problems of urbanised areas is the high degree of pollution, besides the absence of adequate habitat, as environmental contamination negatively impacts amphibian populations (Sparling et al, 2010;Egea-Serrano et al, 2012). The effects of pollution are multiple, and resulted for instance in the decline of Acris crepitans Baird, 1854 (Hylidae) (Reeder et al, 2005), and in the absence of Dryophytes suweonensis (Kuramoto,Firsov, is sandwiched between the city and the coastal line, preserved because of a railway, and mainly used for housing, warehouses, landfills, and wastelands (Fig.…”

Determining the optimal developmental stages of Xenopus laevis for initiating exposures to chemicals for sensitively detecting their feminizing effects on gonadal differentiation

“…The adverse influences of EDCs on the reproductive systems of organisms in water, such as fish and amphibians, have received special attention (McRobb et al, 2014;Sumpter and Johnson, 2008). Due to a semi-aquatic life cycle, aquatic reproduction and a highly permeable skin, amphibians like fish are especially vulnerable to EDCs (Bernanke and Köhler, 2009;Egea-Serrano et al, 2012). Some amphibian species can be feminized by EDCs via mimicking estrogens, altering estrogen levels or other pathways, such as 17␣-ethinylestradiol (EE2), polychlorinated biphenyls (PCBs), atrazine, bisphenol A (BPA), dibutyl phthalate (DBP) (Mosconi et al, 2002;Gyllenhammar et al, 2009;Orton and Tyler, 2015).…”