Using eDNA to detect Craspedacusta sowerbii (freshwater jellyfish) in aquatic ecosystems

The use of Environmental DNA (eDNA) can help detect different species that there are in an ecosystem (Water Science School, 2018). eDNA is nuclear or mitochondrial DNA that is released from an organism into the environment via skin, hair, feces, etc. The use of eDNA is more common in aquatic systems and is becoming more integrated into routine monitoring and management practices (Hinlo, Furlan, Suitor, & Gleeson, 2017). eDNA is commonly used to identify invasive species and can also help to detect species that are not easily visible or catchable (Water Science School, 2018).
Craspedacusta sowerbii is a freshwater cnidarian that was discovered in England in 1880. Craspedacusta sowerbii is a native species from China that adapts to all types of freshwater, and it can now be found in North and South America, Europe, Asia, and Australia. In North America the medusa has been found in approximately 140 geographical sites, more specifically in ponds, among the years 1932 and 1967 (Acker & Muscat, 1976). One of the main characteristics of C. sowerbii is that they are one of few species of Hydrozoa found in freshwater (Acker & Muscat, 1976). The life cycle of Craspedacusta sowerbii includes both polyp (assuming asexual reproduction) and free-swimming stages (involved in sexual reproduction). C. sowerbii grows remarkably well when the water temperature rises (Oualid, et al., 2019). This change in season and increase in water temperature is why large blooms of medusae can be seen during the summer and early fall (Acker & Muscat, 1976).
There are several studies focused on invasive species that conclude that their presence in ecosystems has a great impact on native species. Invasive species can evolutionarily affect native species in different aspects: change of behavior, displacement or even the extinction of the native species (Mooney & Cleland, 2001). No one knows the full extent of the invasion and non-native range of Craspedacusta sowerbii in North America, or their impacts on native species where they are now found. eDNA could provide a unique tool is the case of C. sowerbii, allowing us to detect their presence and track their full invasive range.

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