Thesis subject

MSc thesis topic: Modelling environmental DNA transport in North Sea using Lagrangian particle tracking

The use of environmental DNA (eDNA) in monitoring marine life is rapidly expanding. This molecular method promises advantages over traditional biodiversity and fisheries surveys by being less costly, easy to sample and non-invasive.

While the method considerably advanced over the past decade, major knowledge gaps remain in understanding the behaviour and fate of eDNA in marine environments between shedding and sampling time, which can range from a few days to weeks. After being shed, eDNA gradually degrades while is being transported by the currents away from the release location. The production of eDNA depends on how many animals are present and how much genetic material is being shed. The persistence of eDNA depends on how quickly it degrades under the effect of environmental factors such as temperature and microbial activity. Furthermore, transport of eDNA through advection by ocean currents, dispersion by current shear, eddies, turbulence and diffusion, and gravitational settling in response to density differences with the ambient water further complicates the interpretation of eDNA concentrations measured in environmental samples. These processes are poorly understood in marine environments, such as North Sea. To identify the source location of eDNA, coupled transport and ocean models will be used to reconstruct dispersal pathways of sampled eDNA, integrating processes of eDNA decay with temperature to determine the dispersal duration.

Background

Samples of eDNA were collected on the reefs off the north Scotland coast (see the red cross on the map). A metabarcoding study identified a list of fish species known to live in North Sea, Atlantic and even Arctic. The question remains on the true location of the identified fish species, if the eDNA sampled reflects eDNA transport processes (fish are living in other locations from where the shedded DNA was advected) or local production (fish were visiting or living on the reefs).

Relevance to research/projects at GRS or other groups

Marine Animal Ecology studies response of marine animals to changing environmental conditions. GRS studies spatial distributions of species and associations with environmental conditions. This project has relevance to the applicability of a new method for spatial monitoring of marine life.

Objectives and Research questions

  • Collect data on eDNA decay experiments and find the best function explaining decay rate with temperature.
  • Use Lagrangian particle tracking model to reconstruct dispersal pathways of fish eDNA samples collected on the north coast of Scotland.
  • Apply the decay function on the transport pathways to determine dispersal duration given the temperature in the North Sea and north-east Atlantic.
  • Map the spread and dispersal of eDNA particles and identify the areas of potential source location of sampled eDNA.
  • Determine the true presence-absence for the rare Atlantic species identified with eDNA metabarcoding on the Scottish reefs.

Requirements

  • GIS, spatial data analysis
  • Experience with numerical modelling
  • Familiar with Python or R

Literature and information

Theme(s): Modelling & visualisation; Integrated Land & Sea Monitoring