River regulation influences the composition and distribution of inland frog communities

Abstract

Frogs are widespread through inland rivers and floodplains and are an important component of floodplain food chains. Despite this, studies of frog communities in inland river systems are limited and the impacts of river regulation on frog communities have received very little attention. Surveys for frogs, tadpoles and egg masses along with assessment of vegetation, hydrology and water chemistry were conducted along 10 km reaches of three creek systems in the Lachlan River catchment, a major regulated river in Australia's Murray-Darling Basin. A total of 23 sample sites were surveyed at locations above and below in-stream weirs as well as adjacent floodplain depressions. The hydrological regimes of sample sites were classified according to the length of time that they were known to hold water (water permanence). The sample sites fell into two distinct categories, 14 were classified as permanent and occurred upstream of weirs while nine were classified as temporary and were located downstream of weirs and in depressions adjacent to the weir pool. Permanent sample sites had a significantly higher percentage of dead standing timber and were deeper with less aquatic vegetation cover than temporary sample sites. Seven frog species were identified; there were no significant differences in species richness between permanent and the temporary waterbodies but the composition of frog assemblages differed significantly between them. This suggests that alteration to the hydrology of inland creek systems can lead to changes in the distribution frog species, with some becoming more common due to increases in the availably of permanent waterbodies while others decline due to reductions in the availability of seasonally flooded waterbodies.

Do frogs bounce, and if so, by how much? Responses to the ‘Big Wet’ following the ‘Big Dry’ in south‐eastern Australia

“…Other workers in Australia have identified the influence of water management on habitat characteristics (e.g. permanence and flow) as another pressure affecting amphibians (Wassens & Maher, 2011).…”

“…The effects of landscape change and use of natural resources (e.g. water harvesting and diversions) on the biota have been described extensively (Wallis et al ., ; Wassens & Maher, ). Down‐scaled regional climate‐change projections suggest a 2.5–5 °C increase in mean annual temperature under the 2070 high‐emissions scenario of the Intergovernmental Panel of Climate Change (Hennessy et al ., ).…”

Influence of damming on anuran species richness in riparian areas: A test of the serial discontinuity concept

“…In addition, variability in seasonal flows along regulated rivers has been linked with high mortality of both R. boylii and the California red-legged frog (R. draytonii; Kupferberg et al, 2012). Riparian amphibian species distributions can be altered by flow regulation (Wassens & Maher, 2011) because they are sensitive to changes in temperature (Catenazzi & Kupferberg, 2013), unseasonable or strongly variable flows (Kupferberg, Lind, Thill, & Yarnell, 2011;Lind, Welsh, & Wilson, 1996), reduced downstream flows (Bateman, Harner, & Chung-MacCoubrey, 2008), and breeding habitat loss (Lind, Welsh, & Wilson, 1996). However, the predictions of the SDC have yet to be explicitly examined in relation to riparian amphibian communities which are those occupying habitat adjacent to main river channels.…”

Surface water network structure, landscape resistance to movement and flooding vital for maintaining ecological connectivity across Australia’s largest river basin

“…Although habitat fragmentation and isolation, changes to flooding regimes caused by river regulation, and the spread of disease through habitat networks (e.g., chytridiomycosis) have been suggested as contributing factors, many declines remain poorly understood (Hazell 2003;Stuart et al 2004). Previous research has primarily assessed how changing connectivity and flooding affects amphibian ecology at the site or metapopulation scale rather than across regional-scale habitat networks (e.g., Wassens et al 2008;Wassens and Maher 2011;McGinness et al 2014;Ocock et al 2014). Key doubts also remain about the effectiveness of Australia's protected area systems for conserving the surface water habitats of species like amphibians, particularly given its poor coverage of freshwater ecosystems and the lack of consideration for landscape-scale processes such as flooding or connectivity (Kingsford 2011;Chessman 2013).…”