Resilience to climate change: complex relationships among wetland hydroperiod, larval amphibians and aquatic predators in temporary wetlands

Abstract

Amphibians that utilise temporary wetlands with unpredictable hydrology are living on the edge, maintaining viable populations under variable climatic conditions. Information on their breeding ecology will provide insight into their adaptive capacity and resilience to climate change. The environmental factors influencing breeding of a temporary wetland breeding frog (Litoria olongburensis) from eastern Australia were examined over two breeding seasons from August 2009 to March 2011. The influence of biotic and abiotic wetland characteristics on the abundance and seasonality of L. olongburensis aquatic larvae was quantified throughout the latitudinal range of the species. Substantial variation in yearly precipitation resulted in changes to the timing of breeding, and patterns of tadpole and predator abundance, which also varied along a hydroperiod gradient. Litoria olongburensis displayed adaptive strategies, including breeding when hydrological conditions were likely to last longest, and short time to hatching and metamorphosis. Concentrating breeding efforts early during wetland filling coincided with low predator densities. These pre-adaptations may reflect an adaptive capacity to predicted changes in frequency and reliability of precipitation as a result of climate change, and may apply to other temporary wetland species. Their conservation depends on preserving wetlands with a variety of hydroperiods within a landscape matrix.

Calling phenology and detectability of a threatened amphibian (Litoria olongburensis) in ephemeral wetlands varies along a latitudinal cline: Implications for management

“…Breeding activity can vary intraspecifically along latitudinal or altitudinal gradients because of clinal variation in specific meteorological factors and environmental triggers (Morrison & Hero 2003;Hartel et al 2007;Semlitsch 2008;Canavero et al 2009;Dahl et al 2012;Lowe et al 2015). For example, Lemckert and Mahony (2008) document variation in calling season length between northern and southern populations of some Australian frog species.…”

“…They breed in wetlands that periodically dry out (Lewis & Goldingay 2005;Shuker & Hero 2012;Simpkins et al 2013), which are strongly influenced by the timing and amount of spring and summer rainfall (Griffith et al 2008;Lowe et al 2015). The risk of reproductive failure for L. olongburensis depends on both the delay or lack of annual rainfall and the length of hydroperiod (Lowe et al 2015). Although a lack of rainfall can lead to complete reproductive failure from early wetland desiccation, unusually wet years can lead to extended wetland hydroperiod, which may increase concentrations of aquatic predators (Lowe et al 2015).…”

“…The risk of reproductive failure for L. olongburensis depends on both the delay or lack of annual rainfall and the length of hydroperiod (Lowe et al 2015). Although a lack of rainfall can lead to complete reproductive failure from early wetland desiccation, unusually wet years can lead to extended wetland hydroperiod, which may increase concentrations of aquatic predators (Lowe et al 2015). Thus, the peak in intensity of calling should occur when breeding success is expected to be highest (i.e.…”

“…Males call in most months of the year but are likely to display seasonality in calling intensity and activity (Hines & Meyer 2011). They breed in wetlands that periodically dry out (Lewis & Goldingay 2005;Shuker & Hero 2012;Simpkins et al 2013), which are strongly influenced by the timing and amount of spring and summer rainfall (Griffith et al 2008;Lowe et al 2015). The risk of reproductive failure for L. olongburensis depends on both the delay or lack of annual rainfall and the length of hydroperiod (Lowe et al 2015).…”

“…Thus, it is important to analyse multiple environmental variables concurrently to best predict amphibian calling (Oseen & Wassersug 2002;Steelman & Dorcas 2010). However, because some amphibians are flexible in their response to different climatic conditions each year (Marsh 2000;Lowe et al 2015), isolating key explanatory variables can be challenging.…”