Non-pollen palynomorphs notes: 3. Phototrophic loricate euglenoids in paleoecology and the effect of acetolysis on Trachelomonas loricae

Abstract

Algal palynomorphs are useful indicators of freshwater environments in the past and present, allowing reconstruction of such environmental characteristics as former pH, trophic stage, temperature and salinity. However, the using of algal palynomorphs in paleoecology is restricted by their resistance to natural degradation and acetolysis treatment. In this study, we evaluate the usefulness of the loricate euglenophyte genera Trachelomonas and Strombomonas as paleoecological indicators. In order to evaluate their resistance to degradation, loricae morphology of four Trachelomonas species from the Culture Collection of Algae at Göttingen University (SAG) were studied with and without acetolysis treatment. The experiment demonstrates a strong dissolution under acetolysis of the three species T. hispida, T. lefévrei, T. zorensis and a reduction in the loricae length by T. similis. In the Holocene records, Trachelomonas can be found in non-acetolyzed samples, occurring together with other eutrophication indicators such as cyanobacteria and ciliate Codonella cratera. A review of recent algological literature supports Trachelomonas being a good indicator of organic pollution.