Responsible: Andreas Sandbugt Pettersen
E-mail: andrspet@student.ibv.uio.no
Supervisors: Olli Hyvarinen and Alexander Eiler
Aim
To elucidate the fate and transport of various types of marine environmental DNA to facilitate early detection of invasive species, by using the invasive species Pacific oyster (Crassostrea gigas) as model organism and using the Oslo fjord as a model system
Background
The introduction of invasive species into new habitats poses a significant challenge to global biodiversity, and have severe consequences ecologically and economically. In fact, biological invasions were, in 2019, estimated to have a global annual cost of over $423 billons and will likely increase in the future (IPBES, 2023). Proper strategies in management and prevention to combat invasive species are therefore needed but to date this has proven to be a difficult task, especially in the highly dynamic habitat of the ocean. Efforts to manage invaders are mostly ineffective and are focused on reducing the potential negative impacts after settlement of new species. Once settled eradication is unlikely. In recent years, tools such as environmental eDNA (eDNA) metabarcoding have been proven to facilitate early detection and surveillance of introduced species (Larson et al., 2020).
Compared to traditional monitoring methods, eDNA-metabarcoding is a cost effective, less time consuming and non-invasive method. It allows for monitoring whole ecosystem across several trophic leves, and is a highly sensitive method. As such, it is able to detect small, rare, elusive and other species that are difficult to detect using traditional monitoring methods, such as fishing, diving and net catches (Ruppert et al., 2019; Taberlet et al., 2012).
However, there remains some unresolved challenges with eDNA methods, including the detection of DNA from dead organisms (false positives) and the lack of detection of species that are present at low densities (false negatives), if sampling design is patchy (Sepulveda et al., 2020). Furthermore, the heterogeneous nature of eDNA within a highly dynamic environment complicates interpretations that can be made from eDNA metabarcoding studies. Therefore, understanding the dynamics of marine eDNA within the environment is therefore crucialin understanding and describing the relationship between sampled eDNA and the organisms from which it originates.
Research questions:
- Determine decay rates on various forms of eDNA, membrane bound, dissolvedand particulate, under varying abiotic conditions. The conditions being various temperatures, salinity and microbial activity.
- Estimate sinking rates for membrane bound, dissolved and particulate, eDNA
- Verify that sinking rates, decay rates and wave action can predict the behaviourof different eDNA forms in the water body.
- The estimated parametres will then be incorporated into an oceanographic driftmodel “Opendrift”, to predict how the various fractions of eDNA from the PacificOyster is transported in the water systems.