Environmental variables associated with the distribution and occupancy of habitat specialist tadpoles in naturally acidic, oligotrophic waterbodies CLAY ALAN SIMPKINS, 1 * JONATHAN D. SHUKER, 1 GREGORY W. LOLLBACK, 1 J. GUY CASTLEY 2 AND JEAN-MARC HERO 1 1 Environmental Futures Centre, School of Environment, Griffith University, Parklands Drive, Gold Coast Campus, Gold Coast, Qld 4222, Australia (Email: claysimpkins@hotmail.com), and 2 International Centre for Ecotourism Research, School of Environment, Griffith University, Gold Coast, Queensland, Australia Abstract Environmental factors play an integral role, either directly or indirectly, in structuring faunal assemblages. Water chemistry, predation, hydroperiod and competition influence tadpole assemblages within waterbodies. We surveyed aquatic predators, habitat refugia, water height and water chemistry variables (pH, salinity and turbidity) at 37 waterbodies over an intensive 22-day field survey to determine which environmental factors influence the relative abundance and occupancy of two habitat specialist anuran tadpole species in naturally acidic, oligotrophic waterbodies within eastern Australian wallum communities. The majority of tadpoles found were of Litoria olongburensis (wallum sedge frog) and Crinia tinnula (wallum froglet) species, both habitat specialists that are associated with wallum waterbodies and listed as Vulnerable under the IUCN Red List.Tadpoles of two other species (Litoria fallax (eastern sedge frog), and Litoria cooloolensis (cooloola sedge frog)) were recorded from two waterbodies. Tadpoles of Litoria gracilenta (graceful treefrog) were recorded from one waterbody. Relative abundance and occupancy of L. olongburensis tadpoles were associated with pH and water depth. Additionally, L. olongburensis tadpole relative abundance was negatively associated with turbidity. Waterbody occupancy by C. tinnula tadpoles was negatively associated with predatory fish and water depth and positively associated with turbidity.Variables associated with relative abundance of C. tinnula tadpoles were inconclusive and further survey work is required to identify these environmental factors. Our results show that the ecology of specialist and non-specialist tadpole species associated with ‘unique’ (e.g. wallum) waterbodies is complex and species specific, with specialist species likely dominating unique habitats. Key words: acid frog, acidic waterbody, Crinia tinnula, Litoria olongburensis, tadpole, tadpole assemblage, wallum. INTRODUCTION Environmental factors play an integral role, either directly or indirectly, in structuring faunal assemblages (Krebs 2009). Different species will have varying tolerances to environmental factors (e.g. tadpole intol- erance to varying levels of water pH (reviewed in Pierce 1985); coral intolerance to increasing tempe- rature (Berkelmans & Willis 1999); eel intolerance to increased salinity (Schofield & Nico 2009)), with organisms occurring outside of their tolerance range often resulting in death or deformities (Gosner & Black 1957; Sadinski & Dunson 1992; Schofield & Nico 2009). Therefore, the niches in which a species occurs within a species distributional range will be restricted to areas where environmental variables are within the species tolerance limits. Habitat specialists will often occur within a limited number of habitats while generalist species will occur across several habitat types (Krebs 2009).The absence of habitat specialist species from multiple habitats is likely a result of intolerance to specific environmental factors or competition restricting the species to niches where factors are ideal for survival. For example, in Japan the abundance of grassland specialist grasshop- per species was found to be negatively influenced by the exotic vegetation species Eragrostis curvula (Yoshioka et al. 2010). This relationship was hypoth- esized as being attributed to a decline in food avail- ability or suitable habitat following the introduction of the exotic plant species (Yoshioka et al. 2010). In some environments non-habitat specialist and habitat spe- cialist species are able to coexist within the same habitat (Brown 1996). Alternatively, habitat specialist species and non-habitat specialist species may not co-occur or be restricted in their abundance or occu- pancy within the environment. *Corresponding author. Accepted for publication March 2013. Austral Ecology (2014) 39, 95–105 © 2013 The Authors doi:10.1111/aec.12048 Austral Ecology © 2013 Ecological Society of Australia