Acute and chronic effects of acidic pH on four subtropical frog species

Abstract

Acidic precipitation is implicated as a possible cause of global amphibian decline. Even protected areas such as Kruger National Park receive acid rain which may lead to possible negative effects on the park's natural amphibian populations. We conducted acute (LC 50 ) and chronic acid tolerance bioassays on embryos and tadpoles of four frog species found in the park, i.e., Chiromantis xerampelina (Southern Foam Nest Frog), Pyxicephalus edulis (African Bullfrog), Amietophrynus maculatus (Flat-backed Toad) and Hildebrandtia ornata (Ornate Frog), using survival, deformities and growth as endpoints. Chronic exposure pH-values were selected based on the results of the acute assays. Trimmed Spearman-Karber LC 50 s were 4.07, 4.55, 3.75 and 3.747 for C. xerampelina, P. edulis, A. maculatus and H. ornata, respectively, and were all below the pHs in the natural ponds of the KNP. For chronic exposures tadpole size decreased and tadpole deformities increased with decreasing pH. Metamorphosis of tadpoles was also delayed by increasing acidity. In conclusion, the current buffering capacity of water bodies, which serve as habitat for amphibians, negates the effects of decreasing pH from acid precipitation.

Neutrophil: Lymphocyte Ratios as a Measure of Chronic Stress in Populations of the Hellbender (Cryptobranchus alleganiensis) across a Habitat Quality Gradient

“…In addition to high conductivity, acidic water has been found to negatively affect aquatic organisms through reduced larval growth and delayed metamorphosis (Burmeister, 2015;Farquharson et al, 2016), physiological changes (Neff et al, 2008), and increased mortality (Vatnick et al, 1999;Skei and Dolmen, 2006). Acidic deposition in rivers has long been of concern, especially in the Appalachian Mountains where acidification has caused documented salamander declines (Kucken et al, 1994), and many remaining Hellbender populations reside.…”

Trait-environment relationship in tadpoles of the southern Atlantic Forest

“…Physicochemical components of water may affect the physiology and development of tadpoles, which reflects in compensation mechanisms. Low pH values may affect tadpole growth (Pierce, 1985; Farquharson et al, 2016; Meyer, Franklin, & Cramp, 2020). The traits of nostrils and spiracle are related to the tadpoles’ respiratory and regulatory physiology, water intake and flow into the body (Gollman & Gollman, 1999; Altig, 2006), which has a strong connection the physicochemical properties of water.…”

“…Such environmental characteristics can directly influence the composition of aquatic communities in response to predation and/or competition (Wellborn, Skelly, & Werner, 1996; Werner, Yurewicz, Skelly, & Relyea, 2007; Melo, Garey, & Rossa-Feres, 2018), as well as nutrient supply (Williams, Rittenhouse, & Semlitsch, 2008), thus enabling the distribution of trophic guilds in the water column (Queiroz et al, 2015). They can also influence the metabolism (Afonso & Eterovick, 2007), morphology and physiology of tadpoles (Sipaúba-Tavares, Guariglia, & Braga, 2007; Thomaz & Cunha, 2010; Mansano, Stéfani, Pereira, & Macente, 2012; Mansano, Stéfani, Pereira, Nascimento, & Macente, 2014; Farquharson, Wepener, & Smit, 2016), shaping their performance. This prediction is based on the influence of the landscape on the composition of the tadpole community (Santos et al, in press) and the local characteristics of the water such as depth, presence of vegetation (Queiroz et al, 2015), substrate (Schiesari, 2006; Williams et al, 2008; Thomaz & Cunha, 2010), temperature (Lima, Casali, & Agostinho, 2003; Maciel & Juncá, 2009), pH, nitrogen in the form of ammonia, nitrite and nitrate, phosphorus and bicarbonate (Mansano, Vanzela, Américo-Pinheiro, Macente, Khan, et al, 2018).…”

Complex Organisms Must Deal with Complex Threats: How Does Amphibian Conservation Deal with Biphasic Life Cycles?

“…Altered water chemistry, caused by mining, industrial, and agriculture practices, can negatively impact the aquatic stages of amphibians. Changes in pH levels and the release of coal combustion and heavy metals, such as iron, manganese, and copper, into aquatic environments have been shown to cause acute negative impacts on amphibian larvae and embryos [65,66,121,122]. Salice et al [66] examined the population-level impacts of aquatic coal combustion residue (CCR) on the different life stages of the eastern narrow-mouth toad, (Gastrophryne carolinensis).…”