A Symposium on Amphibian Declines and Habitat Acidification

Pérez-Coll

Environ Health Perspect

1996

The Reconquista River in Argentina is considered a "supercritical" river basin due to environmental degradation. Within its valley of 1.547 km2, there are more than 3 million inhabitants and 12,000 industries. Using early-life-stage toxicity tests with Bufo arenarum embryos (the most sensitive of three native species), we determined the water quality at six sampling stations of the river valley and expressed the results as acute and chronic toxicity units. Along most of the river, the toxicity was higher than the allowable level of whole industrial effluent toxicity recommended by U.S. EPA. In a tributary stream, Arroyo Moron, the water was about 10 times more toxic than the criteria maximum concentration (CMC) recommended by U.S. EPA for industrial effluents. Similar degradation of the water quality was found taking as a reference value an upstream sampling station. In all places where the water quality was worse than the CMC, no macroorganisms were found, and in one of these places, a large number of dead fishes was observed. Our study points out that amphibian early-life-stage toxicity tests could be appropriate for assessing water contamination and water quality, which is essential for diagnosis, protection of environmental services, monitoring, and restoration purposes. Images Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6.

Section: Resultssupporting

confidence: 83%

“…Amphibians are useful indicators of freshwater contamination (9)(10)(11). Embryos of Bufo arenarum, a South American toad, due to their high sensitivity to environmental pollutants (12)(13)(14)(15), could be very useful for ecotoxicological studies and for assessing the water quality needs of widlife (16).…”

mentioning

confidence: 99%

Ecotoxicity in the Reconquista River, province of Buenos Aires, Argentina: a preliminary study.

Pérez-Coll

Environ Health Perspect

1996

“…However, given that Bd was not identified until the late 1990s (Berger et al 1998, Longcore et al 1999, it is possible that some of these species are also rare because of their susceptibility to chytridiomycosis. In the case of northern leopard frogs, past studies have highlighted the role of habitat loss and pond water acidification as possible causes of population decline in this region (Dunson et al 1992, Simon et al 2002, Brodkin et al 2003, Gibbs et al 2005. However, in light of our results, the potential for a combined effect of habitat stress and infection with Bd should not be overlooked.…”

Section: Discussionmentioning

confidence: 59%

First survey for the amphibian chytrid fungus Batrachochytrium dendrobatidis in Connecticut (USA) finds widespread prevalence

Richards-Hrdlicka

Richardson²,

Mohabir³

2013

Dis. Aquat. Org.

The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) is an emerging infectious fungal pathogen of amphibians and is linked to global population declines. Until now, there has only been 1 survey for the fungus in the northeastern USA, which focused primarily on northern New England. We tested for Bd in a large number of samples (916 individuals from 116 sites) collected throughout the state of Connecticut, representing 18 native amphibian species. In addition, 239 preserved wood frog Lithobates sylvaticus tadpoles from throughout the state were screened for the fungus. Bd presence was assessed in both the fresh field swabs and the preserved samples using a sensitive quantitative PCR assay. Our contemporary survey found widespread Bd prevalence throughout Connecticut, occurring in 14 species and in 28% of all sampled animals. No preserved L. sylvaticus specimens tested positive for the fungus. Two common species, bullfrogs R. catesbeiana and green frogs R. clamitans had particularly high infection rates (0.21−0.39 and 0.33−0.42, respectively), and given their wide distribution throughout the state, we suggest they may serve as sentinels for Bd occurrence in this region. Further analyses found that several other factors increase the likelihood of infection, including life stage, host sex, and host family. Within sites, ponds with ranids, especially green frogs, increased the likelihood of Bd prevalence. By studying Bd in populations not facing mass declines, the results from this study are an important contribution to our understanding of how some amphibian species and populations remain infected yet exhibit no signs of chytridiomycosis even when Bd is widely distributed.

Environmental Health Perspectives

“…Currently, freshwater fish and birds feeding in lakes are the most extensively studied organisms (1). Although global population declines are under way for many amphibian (19)(20)(21) and chondrichthian (22,23) species, no published studies are available on the biological effects of sublethal doses of chemicals with known endocrine-disrupting or reproductive activities in these species. Could these declines be attributed, in part, to the deleterious effects of such contaminants?…”

Section: Recommendation Onementioning

confidence: 99%

Defining the Role of Pollutants in the Disruption of Reproduction in Wildlife

Hose¹,

Guillette²

1995

Although chemical exposure has been associated with reduced reproduction in certain North American fish, reptiles, and mammals, definitive causeand-effect data are lacking in many instances. Because the increasing use and global transport of industrial chemicals pose significant risk to successful reproduction, methods should be developed that can define the geographic extent and magnitude of injury and risk to wildlife. Because industrial chemicals are articles of commerce, information about injury to wildlife has been contentious and too often ineffective in changing societal behavior. The following strategies are advocated for inferring causal relationships. First, a balanced and comprehensive assessment of the data is necessary to determine the geographic extent of exposure and reproductive effects associated with environmental pollution. Initial efforts to document reproductive injury should focus on specific ecosystems in which detrimental effects have been observed, but lack sufficient causal data. Model systems (including experimental mesocosms or field ecosystems) should be identified or designed that can adequately test multigenerational reproductive effects. Mechanistic data from supportive laboratory studies on reproductive toxicity, quantitative structure-activity relationships, and bioaccumitlation can be used to predict effects of related pollutants and to determine risk. Such information is essential to prevent future injury to wildlife and to prioritize the numerous remediation decisions facing our society. -Environ Health Perspect 1 03(Suppl 4): 87-91 (1995)