Dr John Pearman1, Dr Susie Wood, Dr Sean Waters, Dr Javier Atalah, Janet Adamson, Georgia Thomson-Laing, Lucy Thompson, Dr Marcus Vandergoes, Lakes380 team
1Cawthron Institute, Nelson, New Zealand
Lakes provide key ecosystem services and are culturally significant. However, lake environments are vulnerable to perturbations and this is being exacerbated by increasing anthropogenic pressures. Surface sediments act as a natural archive accumulating chemicals and nutrients, often derived from the lake catchment. Microbial taxa are numerically dominant in surface sediments and play critical roles in biogeochemical cycling. Their rapid responses to changes in environmental conditions means that they have a potential to act as indicators of lake health. In this study, we utilise high throughput sequencing of the 16S rRNA gene to investigate the spatial patterns of surface sediment microbial communities from 255 lakes spread across a wide range of gradients in New Zealand. Using a subset of data consisting of lakes which are regularly monitored, we identify bacterial taxa which are indicative of different levels within the Trophic Lake Index (TLI). These indicator taxa formed the basis of the development of a Sediment Bacterial Trophic Index (SBTI) which correlated strongly with the conventional TLI. The SBTI was then derived for the unmonitored lakes, providing new knowledge on their trophic state. Further, we utilize the SBTI in a paleolimnological context to investigate changes in trophic status over centuries to millennia. This new, robust DNA-based tool provides a rapid and cost- efficient method that will allow a greater number of lakes to be monitored and more effectively managed in New Zealand and globally.
Biography:
John Pearman is a molecular ecologist. The completed his PhD at the University of Warwick, UK focusing on the diversity and transcriptomics of photosynthetic picoeukaryotes in the Atlantic Ocean. After this he spent just under seven years working at King Abdullah University of Science and Technology (KAUST) investigating the ecology of Red Sea organisms using metabarcoding approaches. He focussed on a range of organisms from planktonic bacteria to coral reef invertebrates. For the last two years he has worked on the Lakes380 project at the Cawthron Institute, NZ. This project has involved using metabarcoding approaches to investigate contemporary and historical changes in lake communites.