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

Abstract

Changes in climate and the introduction of invasive species are two major stressors to amphibians, although little is known about the interaction between these two factors with regard to impacts on amphibians. We focused our study on an invasive tree species, the Chinese tallow (Triadica sebifera), that annually sheds its leaves and produces leaf litter that is known to negatively impact aquatic amphibian survival. The purpose of our research was to determine whether the timing of leaf fall from Chinese tallow and the timing of amphibian breeding (determined by weather) influence survival of amphibian larvae. We simulated a range of winter weather scenarios, ranging from cold to warm, by altering the relative timing of when leaf litter and amphibian larvae were introduced into aquatic mesocosms. Our results indicate that amphibian larvae survival was greatly affected by the length of time Chinese tallow leaf litter decomposes in water prior to the introduction of the larvae. Larvae in treatments simulating warm winters (early amphibian breeding) were introduced to the mesocosms early in the aquatic decomposition process of the leaf litter and had significantly lower survival compared with cold winters (late amphibian breeding), likely due to significantly lower dissolved oxygen levels. Shifts to earlier breeding phenology, linked to warming climate, have already been observed in many amphibian taxa, and with most climate models predicting a significant warming trend over the next century, the trend toward earlier breeding should continue if not increase. Our results strongly suggest that a warming climate can interact with the effects of invasive plant species, in ways we have not previously considered, to reduce the survival of an already declining group of organisms.

Environmental drivers of anuran calling phenology in a seasonal Neotropical ecosystem

“…; Saenz et al . ). Although extreme weather events (e.g., drought) can negatively affect amphibian reproductive activity (Jansen et al .…”

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

“…Dissolved oxygen measurements at similar conditions (initial 1 g/L R. cathartica litter) revealed nearly anoxic levels (range for 20 °C was 0.13-0.36 mg/L; at 25 °C it was 0.10-0.17 mg/L), which likely caused the death of the young tadpoles. Decreased dissolved oxygen associated with the breakdown of invasive plant material has been reported by others, particularly at higher concentrations of this plant material (Cohen et al 2012;Saenz et al 2013;Earl et al 2014). Whereas the genus Lithobates has lower oxygen consumption rates and may tolerate lower oxygen levels, other genera may not be able to withstand the lower oxygen levels associated with the presence of R. cathartica (Bennett 1978).…”