Species- and Trait-Based Reconstructions of the Hydrological Regime in a Tropical Peatland (Central Sumatra, Indonesia) during the Holocene Using Testate Amoebae

Paleoecological reconstructions of hydrological regimes in tropical peatlands during the Holocene are important for the estimation of their responses to changing environments. However, the application of some widely used proxies, such as testate amoebae, is hampered by poor knowledge of their morphology and ecological preferences in the region. The aim of this study is to describe the morphospecies composition of sub-fossil testate amoebae in deposits of a tropical peatland in Central Sumatra (Indonesia) during the Holocene and reconstruct the hydrological regime using morphospecies- and functional-trait-based approaches. In total, 48 testate amoeba morphospecies were observed. Based on morphospecies composition, we distinguished three main periods of peatland development (13,400–8000, 8000–2000, 2000 cal yr BP–present). The application of the morphospecies-based transfer function provided a more reliable reconstruction of the water regime in comparison to the functional trait-based one. The weak performance of the latter might be related to the poor preservation of shells and the greater variation in the functional traits in sub-fossil communities as compared to the training set and linear modeling approach. These results call for future studies on the functional and morphospecies composition of testate amoebae in a wider range of tropical peatlands to improve the quality of hydrological reconstructions.