Sediment pigments as biomarkers of environmental change

Abstract: This thesis demonstrates the usefulness of sedimentary pigments as biomarkers of environmental change in estuarine systems and as biomarkers in lakes in relation to climate change. These are two fields where sediment pigment records as measured by high-performance liquid chromatography (HPLC) are emerging areas of study. A detailed study was undertaken to examine the effects of different storage of sediment samples on pigment concentrations and resulted in recommendations to obtain the best quality data with storage of samples. In estuarine systems, pigments in the sediment record were found to reflect the phototrophic community of different systems as well as major changes in eutrophication conditions. However, it was also recognized that the quality of the pigment record is highly dependent on the preservation regime in the sediment. Therefore, selection of an appropriate investigation site is of utmost importance in determining the impacts of environmental change. The pigment record reliably identified major differences in Arctic lake response to climate change, and emphasized the importance of in-lake processes and location in mediating the response. Strongly stratified lakes showed the largest variability while lakes dominated by benthic algae were more stable. Pigment biomarkers are particularly valuable in multi-proxy studies where they can provide a more complete picture of the phototrophic community and where they are often the only fossil remains of non-siliceous algae and phototrophic bacteria.