Investigating marine vertebrate communities and populations through seawater environmental DNA

• Main Author: Sigsgaard, Eva Egelyng
• Format: Book
• Language: English
• Published: Natural History Museum of Denmark, Faculty of Science, University of Copenhagen 2018
• Subjects: Subarctic
• Online Access: https://curis.ku.dk/portal/da/publications/investigating-marine-vertebrate-communities-and-populations-through-seawater-environmental-dna(af9575ea-a213-4244-9de2-1a9e0b3dd4ac).html; https://soeg.kb.dk/permalink/45KBDK_KGL/1pioq0f/alma99122024947305763

This PhD thesis investigates the potential for studying marine vertebrates by isolating and sequencing the DNA they leave behind in their environment (eDNA). The research is based on metabarcoding; the use of short genetic barcodes to identify many species simultaneously from a mixture of DNA, in this case obtained through filtration of seawater samples. The approach is tested at the species- and population level, in temperate, subarctic and subtropical marine environments. In Paper I, the whale shark Rhincodon typus is used as a test case for extracting populationlevel genetic information from seawater eDNA. The availability of a collection of tissue samples from a seasonal aggregation of whale sharks in Qatar, the Persian/Arabian Gulf, and a significant reference material of DNA sequences from around the world provided a unique possibility to validate eDNA-based population studies. In Paper II, comparison between eDNA concentrations in seawater samples and biomass and abundance data from trawling are used to test whether species-level quantitative information can be obtained from seawater eDNA. In Paper III, a temperate marine fish community in Denmark is followed over one year based on eDNA sampling and visual census by snorkeling. Results from eDNA are compared to snorkeling results, and the degree to which eDNA composition reflects seasonal changes in the community is investigated. In Paper IV, a range of marine habitat types in the Persian/Arabian Gulf are sampled for vertebrate eDNA to test whether eDNA composition is correlated to habitat type, and how well the local and regional diversity of marine vertebrates is covered through eDNA sampling. At the end of the thesis is a list of additional contributions, which are papers that were published or submitted to a journal during my PhD studies, and which are related to the work presented in the thesis.