Leaf litter of invasive Chinese tallow (Triadica sebifera) negatively affects hatching success of an aquatic breeding anuran, the Southern Leopard Frog (Lithobates sphenocephalus)

Abstract

Chinese tallow (Triadica sebifera (L.) Small) is an aggressive invasive tree species that can be abundant in parts of its non-native range. This tree species has the capability of producing monocultures, by outcompeting native trees, which can be in or near wetlands that are utilized by breeding amphibians. Existing research suggests that leaf litter from invasive Chinese tallow reduces survival in larval anurans. The purpose of this study was to determine the effects of Chinese tallow leaf litter on anuran eggs. We exposed eggs of the Southern Leopard Frog (Lithobates sphenocephalus (Cope, 1886)) at various stages of development to different concentrations of Chinese tallow leaf litter to determine survival. Eggs in the earliest stages of development that we exposed to tallow leaf litter died, regardless of concentration; however, some more-developed eggs exposed to tallow leaf litter did hatch. We determined that the greater the concentration of tallow leaf litter, the lower the dissolved oxygen and pH levels we observed. We suggest that changes in these water-quality parameters are the cause of the observed mortality of anuran eggs in our experiments. Eggs exposed to water containing tallow leaf litter with dissolved oxygen <1.59 mg/L and a pH <5.29 did not survive to hatching.Résumé : Le suif végétal de Chine (Triadica sebifera (L.) Small) est une essence d'arbre envahissante agressive qui peut localement être abondante hors de son aire de répartition naturelle. Cette essence est capable de produire des monocultures en délogeant des essences indigènes pouvant se trouver dans des zones humides ou à proximité et que des amphibiens utilisent pour la reproduction. Les travaux existants suggèrent qu'une couverture de feuilles mortes de suif végétal de Chine réduit la survie de larves d'anoures. Le but de l'étude consiste à déterminer les effets des feuilles mortes de suif végétal sur les oeufs d'anoures. Nous avons exposé des oeufs de grenouille léopard du Sud (Lithobates sphenocephalus (Cope, 1886)) à différents stades de leur développement à différentes concentrations de feuilles de suif végétal dans la couverture de feuilles mortes afin de déterminer leur taux de survie. Les oeufs exposés aux stades les plus précoces de leur développement à des feuilles mortes de suif végétal sont morts, peu importe la concentration de ces dernières, alors que certains oeufs à des stades plus avancés ont éclos. Nous avons déterminé que plus la concentration de feuilles mortes de suif végétal dans la couverture était grande, plus les teneurs d'oxygène dissous et le pH étaient faibles. Nous suggérons que les modifications de ces paramètres de qualité de l'eau sont à l'origine de la mortalité observée parmi les oeufs d'anoures dans nos expériences. Les oeufs exposés à de l'eau contenant des feuilles mortes de suif végétal et présentant des teneurs d'oxygène dissous <1,59 mg/L et un pH <5,29 n'ont pas survécu jusqu'à l'éclosion.

Synergistic effects of the invasive Chinese tallow (Triadica sebifera) and climate change on aquatic amphibian survival

“…(), Cotten et al. (), Adams and Saenz (), and this study all report colleting eggs in late January, while Saenz et al. () collected eggs in December.…”

“…; Watling et al. ; Adams and Saenz ), this study indicates that amphibian breeding phenology and timing of leaf fall will ultimately determine the impact of Chinese tallow. Local weather is an important driver of amphibian breeding and Chinese tallow leaf fall phenology (Cameron and Spencer ; Oseen and Wassersug ; Saenz et al.…”

“…In addition to calling data, a small number of published studies have reported on the collection of southern leopard frog eggs in the field in eastern Texas. Johnson et al (2003), Cotten et al (2012), Adams and Saenz (2012), and this study all report colleting eggs in late January, while Saenz et al (2003) collected eggs in December. In an unpublished study in eastern Texas, Saenz et al (unpubl.…”

“…We found tadpole survival to be lowest when exposed to Chinese tallow leaf litter that was submerged in water for the shortest amount of time. Low survival of southern leopard frog tadpoles could have been caused directly by temporary effects of toxic tannins leached from leaves or by short-term changes in water chemistry due to the chemical and physical breakdown of leaves and associated microbial activity (Adams and Saenz 2012). Toxic effects of tannins on aquatic organisms can happen soon after leaves are immersed in water (Tremolieres 1988).…”

Invasion Complexities: The Diverse Impacts of Nonnative Species on Amphibians

“…Hyla versicolor showed significant morphological and developmental differences between treatments. Adams and Saenz (2012) demonstrated similar effects of Chinese Tallow on eggs of Lithobates sphenocephalus. All eggs exposed to Chinese Tallow leaf litter died, regardless of concentration.…”