Nitrogen pollution: an assessment of its threat to amphibian survival.

Abstract

The potential for nitrate to affect amphibian survival was evaluated by examining the areas in North America where concentrations of nitrate in water occur above amphibian toxicity thresholds. Nitrogen pollution from anthropogenic sources enters bodies of water through agricultural runoff or percolation associated with nitrogen fertilization, livestock, precipitation, and effluents from industrial and human wastes. Environmental concentrations of nitrate in watersheds throughout North America range from < 1 to > 100 mg/L. Of the 8,545 water quality samples collected from states and provinces bordering the Great Lakes, 19.8% contained nitrate concentrations exceeding those which can cause sublethal effects in amphibians. In the laboratory lethal and sublethal effects in amphibians are detected at nitrate concentrations between 2.5 and 100 mg/L. Furthermore, amphibian prey such as insects and predators of amphibians such as fish are also sensitive to these elevated levels of nitrate. From this we conclude that nitrate concentrations in some watersheds in North America are high enough to cause death and developmental anomalies in amphibians and impact other animals in aquatic ecosystems. In some situations, the use of vegetated buffer strips adjacent to water courses can reduce nitrogen contamination of surface waters. Ultimately, there is a need to reduce runoff, sewage effluent discharge, and the use of fertilizers, and to establish and enforce water quality guidelines for nitrate for the protection of aquatic organisms. Images Figure 1 Figure 2

Pond Acidification May Explain Differences in Corticosterone among Salamander Populations

“…For instance, it is estimated that approximately 117 million tons of ammonia is produced globally each year, most of it in the form of fertilizer for agriculture (Erisman et al 2007). This has resulted in dramatic changes over time in the global nitrogen cycle, including increased nitrogen inputs to many aquatic systems and subsequent impacts on amphibians ranging from sublethal impacts on growth, development, and behavior to direct mortality (Rouse et al 1999;Mann et al 2009). Acid deposition (e.g., from acid rain) and increased salinity from road deicers have also been identified as possible threats for amphibians (Rowe et al 1992;Collins and Russell 2009).…”

“…Water temperature (ЊC) and pH entered the model as continuous predictors. Chloride (ppb) also entered as a continuous variable but after a (Rouse et al 1999). The pH levels we observed were also in the range of previously published data from sites where Ambystoma breeding can occur (Freda and Dunson 1986;Batzer et al 2004;Carrino-Kyker and Swanson 2007).…”

Improving global environmental management with standard corporate reporting

“…There are several potential thresholds of interest with regard to water quality. Some pollutants will cause no adverse effect at sufficiently low concentrations, cross a threshold where an adverse effect is detectable, and cross another series of thresholds where conditions become lethal for various freshwater species or have human health impacts (99). At the global and national level, we recommend focusing on identifying areas with relatively high nitrogen and phosphorous loading in streams.…”

Altered Ovarian Steroids in Xenopus Laevis Exposed to Environmentally Relevant Concentrations of Nitrate

“…Within the United States, agricultural nitrogen contributions have increased 20-fold in the past 50 years, because of poorly regulated runoff of nitrogen-based fertilizers and animal wastes (Puckett, 1995;Rouse et al, 1999). Within urban areas, nitrate infiltrates aquatic ecosystems primarily through release of industrial and wastewater effluents from treatment plants, runoff of fertilizer applied to lawns and golf courses, and air pollution from the burning of fossil fuels (Rouse et al, 1999). In North America, fertilizers applied adjacent to waterways, coupled with spring rainstorms, contribute to a pulse of nitrate entering aquatic habitats that coincides with the breeding season of many amphibians (Rouse et al, 1999).…”

“…Within urban areas, nitrate infiltrates aquatic ecosystems primarily through release of industrial and wastewater effluents from treatment plants, runoff of fertilizer applied to lawns and golf courses, and air pollution from the burning of fossil fuels (Rouse et al, 1999). In North America, fertilizers applied adjacent to waterways, coupled with spring rainstorms, contribute to a pulse of nitrate entering aquatic habitats that coincides with the breeding season of many amphibians (Rouse et al, 1999).Nitrate is highly soluble in water and, if ingested or absorbed transdermally, is readily transported across the epithelium of the small intestine (Ellis et al, 1998;Iizua et al, 1999). Numerous investigations of tadpoles exposed to environmentally relevant concentrations of nitrate have demonstrated altered behaviors (Hecnar, 1995;, movement patterns (Xu and Oldham, 1997), growth rates, development (Baker and Waights, 1993, 1994;Edwards et al, 2006), gonadal morphology (Orten et al, 2006), and mortality rates Smith et al, 2005Smith et al, , 2006.…”