Instituto de Investigación en Recursos Cinegéticos (IREC) CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13071 Ciudad Real, Spain.
Aquat Toxicol. 2012 Apr;110-111:170-6. doi: 10.1016/j.aquatox.2012.01.010. Epub 2012 Jan 23.
Temporary ponds where many amphibians breed experience a gradual desiccation that leads to growing larval densities, which can reduce tadpole survival rates and increase cannibalistic interactions among carnivorous salamander larvae. Concentrations of many agrochemicals, including nitrogenous fertilizers, can also increase as the water volume decreases. We analyzed the effects of ammonium nitrate fertilizer at two larval densities on growth and survival of Rana dalmatina tadpoles, and on cannibalistic behaviors of Salamandra salamandra larvae. We observed synergistic lethal effects until day 17 of exposure, when ammonium nitrate-related mortality of tadpoles was five times greater at high than at low density. The fertilizer impaired tadpole growth. This effect was stronger at low density than at high density. In the absence of ammonium nitrate, the incidence of cannibalism was higher at high than at low larval density. However, fertilizer exposure removed this density-dependent effect, which, under field conditions, would negate some potentially advantageous effects of cannibalism such as reduced intraspecific competition and the stimulation of defensive behaviors.
许多两栖动物在临时池塘中繁殖，这些池塘会逐渐干涸，导致幼虫密度增加，从而降低蝌蚪的存活率，并增加肉食性蝾螈幼虫之间的同类相食行为。随着水体体积减少，许多农用化学品（包括氮肥）的浓度也会增加。我们分析了硝酸铵肥料在两种幼虫密度下对达尔马提亚蟾蜍蝌蚪的生长和存活，以及对蝾螈幼虫同类相食行为的影响。我们观察到协同致死效应，直到暴露的第 17 天，此时高幼虫密度下的硝酸铵相关死亡率比低幼虫密度下高 5 倍。肥料会损害蝌蚪的生长。这种影响在低密度下比在高密度下更强。在没有硝酸铵的情况下，高密度下的同类相食发生率高于低密度下。然而，肥料的暴露消除了这种密度依赖性效应，在野外条件下，这种效应可能会抵消同类相食的一些潜在有利影响，例如减少种内竞争和刺激防御行为。
