Dr John Pearman1, Mr Reece Martin2, Dr Russleigh Parai3, Mr Kane Andrew1, Dr Sean Waters4, Prof Susie Wood5
1Cawthron Institute, Nelson, New Zealand, 2Matana Consulting, Lower Hutt, New Zealand, 3Kaitiaki ko Ika, Takapuwahia, New Zealand, 4Parker Resolutionz Ltd, Nelson, New Zealand, 5Lincoln University, Lincoln, New Zealand
Biography:
John Pearman is a molecular ecologist with experience working in aquatic environments.
His current work at the Cawthron Institute, New Zealand has focussed on using metabarcoding and metagenomics to assess the health of lakes on a national scale. This has involved the development of eDNA sediment bacterial trophic index for lakes based on 16S rRNA metabarcoding. His current work is using metagenomics to assess the multiple stressors impacting lakes. He has also helped to develop the Pest Alert Tool and BIOWATCH tools which analyse metabarcoding data for non-indigenous species. Prior to working at Cawthron he undertook postdoctoral work at King Abdullah University of Science and Technology (KAUST) investigating the ecology of Red Sea organisms using molecular approaches. This involved using metabarcoding of environmental samples from a range of organisms, from planktonic bacteria to coral reef invertebrates, and habitats encompassing oligotrophic surface waters, to marine sediments and coral reefs.
Abstract:
Microbial communities underpin nutrient cycling across aquatic ecosystems and are strongly influenced by human disturbance. Lakes communities respond not only to within lake stressors that directly impact them, but also integrate disturbances from their catchments, making them early warning systems for anthropogenically induced change at local to regional scales. To better understand how these anthropogenic pressures shape microbial communities in lake surface sediments, it is essential to disentangle natural sources of variation such as spatial differences within a lake and seasonal variability. To address these questions spatio-temporal analysis was undertaken on two case study lakes, Lake Oporoa and Lake Moawhitu. Five sites spread across each lake were investigated in both summer and winter to understand how microbial functioning in the surface sediments was affected both spatially and seasonally. Using metagenomic sequencing of surface sediment DNA we showed that the lakes had a distinct microbial community and functional genes. In both lakes strong seasonal shifts were noted in the composition and functioning of the microbial community with Actinomycetes becoming more prevalent in the winter samples of both lakes while methanogenesis undertaken by various archaea had higher gene abundances in Lake Oporoa in summer. Spatial patterns were not as clear as the seasonal patterns in both lakes. These results indicate that seasonal patterns were a stronger driver of microbial community composition and function compared to within lake spatial patterns. However, between lake differences were the strongest driver indicating that metagenomics could be used to understand how different stressors affect lakes.