Toward more accurate temperature reconstructions based on oxygen isotopes of subfossil chironomid head-capsules in Australia

This study investigates the potential of applying stable oxygen isotopes (δO) from head capsules (HCs) of subfossil chironomids (subfamily Tanypodinae) to reconstruct past temperature changes from south-eastern Australia. The study reports δO results from Tanypodinae HCs in nine lakes. The relationship between δO values of Tanypodinae HCs in lakes and summer (February) air temperature is robust (r = 0.84) supporting its potential to be applied as a temperature proxy in the Australian region. The comparison of these results with the δO values measured on Chironomus spp. HCs from the same lakes reveals differences between the two groups. δO values of Tanypodinae HCs have a stronger correlation with the δO of lake water, δO of precipitation and air temperature as compared with Chironomus δO values. This suggests that Tanypodinae HCs are superior targets to Chironomus spp. for temperature reconstructions. Our data indicate that the δO of Tanypodinae HCs could perform as well as the assemblage based chironomid transfer function from the Australian mainland. We recommend analysis of HCs from additional lakes to develop a more robust calibration curve relating Tanypodinae HC δO to temperature