Warmer temperature modifies effects of polybrominated diphenyl ethers on hormone profiles in leopard frog tadpoles (Lithobates pipiens)

Abstract

Amphibian populations have been declining, and climate change and exposure to environmental contaminants are thought to be involved. Higher water temperature accelerates larval development; however, its combined effects with contaminants and their influence on hormones during metamorphosis are poorly understood. The authors investigated changes in whole-body triiodothyronine (T3) and corticosterone concentrations in developing leopard frogs reared at 23 °C and 28 °C on diets with 0 ng g , 6 ng g , and 37 ng g of a technical mixture of polybrominated diphenyl ethers (PBDE; DE-71) from 10 d to 44 d (premetamorphosis to late climax; Gosner Stages 28 to 46). Unlike controls, PBDE-exposed tadpoles (6 ng g ) reared at 23 °C failed to show any increase in T3 concentrations throughout metamorphosis, and exposed tadpoles reared at 28 °C showed a lower peak at climax compared to controls. Corticosterone levels progressively increased throughout metamorphosis, but the levels were higher in PBDE-exposed tadpoles compared to controls at both temperatures. At the warmer temperature, corticosterone increase occurred earlier (at early climax) in controls and exposed tadpoles compared to tadpoles reared at the cooler temperature (late climax), coinciding with the faster development observed at 28 °C. Tadpoles reared at 28 °C were longer and developed faster than tadpoles reared at 23 °C. At both temperatures, PBDE exposure decreased T3 and increased corticosterone concentrations, which can potentially impair developing tadpoles. Environ Toxicol Chem 2017;36:120-127. © 2016 SETAC.

Thyroid hormone levels and temperature during development alter thermal tolerance and energetics ofXenopus laevislarvae

“…Although previous studies have examined the impact of stress-induced alteration of TH levels on metamorphic and physiological traits of anuran larvae, studies have rarely examined the interaction of different stressors which is known to affect amphibian metamorphosis under natural conditions ( Rowe et al , 1998 ; Freitag et al , 2017 ). This study examined the interactive effects of temperature and altered TH levels on the capacity for physiological acclimation (SMR and thermal tolerance) at the onset of metamorphosis in larvae of Xenopus laevis.…”

Increased Temperature Influenced Growth and Development of Lithobates pipiens Tadpoles Exposed to Leachates of the Invasive Plant European Buckthorn (Rhamnus cathartica) and a Triclopyr Herbicide

“…Whereas some studies have found that warmer temperatures can increase tadpole growth and decrease developmental time, others have shown a reduction in size likely associated with increased metabolism at warmer temperatures (Rohr et al 2011; O'Regan et al 2014). In the present study, tadpoles were provided with abundant food; therefore, the results observed could have resulted from temperature‐driven effects on development and growth, such as earlier increases in hormones at warmer temperatures (Freitas et al 2017).…”

How do pesticides affect bats? – A brief review of recent publications

“…Pesticide residues have been associated with delays in the metamorphosis of anurans, bioaccumulation in wild birds and mammals, and reduction in bee and bird populations (Eqani et al, 2013;Freitas et al, 2017;Köhler and Triebskorn, 2013;Mullin et al, 2016). The American Bald Eagle is a classic example of population decline induced by pesticides.…”