Does sampling location, target species and methodology effect detection of fish DNA in lake sediment core samples?

Miss Georgia Thomson-laing1,2, Dr Jamie  Howarth2, Dr Marcus Vandergoes3, Dr Susie Wood1

1Cawthron Institute, Nelson, New Zealand, 2Victoria University of Wellington, Wellington, New Zealand, 3GNS Science, Lower Hutt , New Zealand

Abstract:

The emergence of environmental DNA detection methods provides an opportunity to track long-term changes in biological communities in lake ecosystems. Lake sedimentary DNA (sedDNA) has been successfully analysed for various aquatic organisms, ranging from photosynthetic microbes to zooplankton and fish. However, the detection of larger organisms, such as fish, has only been reported in a few studies to date. These limited detections are thought to be due to low amounts of fish DNA in the sediment as well as the heterogenous in-lake distribution of fish. We investigated whether historical fish sedDNA could be detected in lake sediment cores and how this detection was impacted by sampling location, target species and the molecular detection method (i.e., targeted or community-based). Sediment cores (ca. 2 m long) were collected from a depocenter and littoral site in Lake Pounui, New Zealand. Sediment subsamples were analysed by droplet digital PCR (ddPCR) for targeted fish species (Anguilla dieffenbachia, Anguilla australis, Perca fluviatilis, Salmo trutta and Oncorhynchus mykiss) and by metabarcoding (using fish specific primers) to assess the total fish community. Fish sedDNA was successfully detected in historical lake sediment. More fish sedDNA was detected in the littoral core in comparison to the depocenter core, and detection in both was temporally patchy and species-specific. For targeted species, ddPCR was more sensitive than metabarcoding. This research highlights the possibilities and limitations of using current molecular techniques to target fish sedDNA in a historical context.


Biography:

Georgia Thomson-Laing is PhD student through Victoria University of Wellington, working at the Cawthron Institute in Nelson, New Zealand. She gained her Master of Science in zoology at the University of Otago, studying fish physiology, specifically the reproduction of New Zealand freshwater eels. Currently, her work is predominantly focused on using environmental DNA (i.e., metabarcoding, droplet digital PCR) as an emerging technology in freshwater ecology and investigating this as part of the wider Lakes380 project that aims to characterise the health of New Zealand lakes.

Date

Mar 21 - 23 2022
Expired!