Invasive fish frequently negatively affect amphibian populations around the world. In agricultural regions of the world, the effects of invasive fish on amphibians may coincide with pollution by agricultural fertilizers. We conducted a mesocosm experiment to examine the potential independent and interactive effects of introduced Western Mosquitofish (Gambusia affinis) and ammonium nitrate, an agricultural fertilizer, on Green Frog (Lithobates clamitans) tadpoles. Mosquitofish had a negative effect on the survivorship of Green Frog tadpoles. Green Frog tadpoles from mesocosms with mosquitofish were larger than tadpoles from mesocosms without mosquitofish, possibly due to a thinning effect that reduced intraspecific competition, as well as increased primary productivity. Ammonium nitrate additions did not affect survivorship in Green Frogs. However, Green Frog tadpoles in ammonium nitrate addition treatments were larger than those from treatments without ammonium nitrate addition, possibly due to increased phytoplankton abundance. In conclusion, mosquitofish and ammonium nitrate addition each had independent and additive effects on Green Frog tadpoles, but there was no evidence for significant interactions between these two stressors. Our results suggest that environmental stressors can have additive effects in some systems and that introduced fish predators may have greater impacts on amphibian populations than low level chemical contamination.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 2013 • No. 2